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Sample records for baumannii expanding multiresistant

  1. Post-surgical meningitis due to multiresistant Acinetobacter baumannii. Effective treatment with intravenous and/or intraventricular colistin and therapeutic dilemmas.

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    Paramythiotou, E; Karakitsos, D; Aggelopoulou, H; Sioutos, P; Samonis, G; Karabinis, A

    2007-02-01

    Post-surgical meningitis and/or ventriculitis caused by Gram-negative bacteria may be difficult to treat due to the emergence of multiresistant strains. Two patients with multiresistant Acinetobacter baumannii central nervous system infection, successfully treated with either intravenous and/or intraventricular colistin are presented. Unresolved issues such as dose and duration of intraventricular colistin are discussed.

  2. Identification of a new geographically widespread multiresistant Acinetobacter baumannii clone from European hospitals.

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    van Dessel, Helke; Dijkshoorn, Lenie; van der Reijden, Tanny; Bakker, Nancy; Paauw, Armand; van den Broek, Peterhans; Verhoef, Jan; Brisse, Sylvain

    2004-03-01

    The aim of the study was to investigate the genetic diversity of Acinetobacter baumannii clinical strains that had previously been allocated to three major groups based on automated ribotyping. Forty-seven isolates from European hospitals and one isolate from a South African hospital, geographically representative of the three ribogroups (ribogroups 1, 2 and 3 with 10, 23 and 15 isolates, respectively), were analysed using the highly discriminatory fingerprinting methods AFLP and pulsed-field gel electrophoresis (PFGE). Based on AFLP data, the isolates clustered into three main groups, each corresponding to one ribogroup. Inclusion of reference strains of the previously described clones I and II, responsible for outbreaks in northwestern European hospitals, showed that ribogroups 1 and 2 correspond to clones I and II, respectively, whereas ribogroup 3 apparently represents a new clone. This clone III was found in France, The Netherlands, Italy and Spain. Clones I and II were not limited to northwestern European countries, as they were also recovered from Spain, South Africa, Poland and Italy (clone I) and from Spain, Portugal, South Africa, France, Greece and Turkey (clone II). Combined AFLP and PFGE data showed intraclonal diversity and led to the distinction of 23 different genotypes. Three genotypes, two of them belonging to clone II and one to clone III, were found in different hospitals and may correspond to subsets of isolates with a more recent clonal relationship, which emphasizes the epidemic potential of these organisms.

  3. Colistin-daptomycin, colistin-linezolid, colistin-vancomycin combination effects on colistin in multi-resistant acinetobacter baumannii strains

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    Irvem, Arzu

    2018-01-01

    Objective: The most important problem in the treatment of nosocomial Acinetobacter baumannii (A. baumannii) infections which is increasingly seen in recent years is that almost all strains are resistant to many antibiotics, including carbapenems, and that the extinction of antibiotic options to be used in treatment. This leads the clinicians to new treatment options and suggests the use of combined antibiotics to achieve success in both the treatment of multi-drug-resistant A. baumanni...

  4. A three-point time series study of antibiotic usage on an intensive care unit, following an antibiotic stewardship programme, after an outbreak of multi-resistant Acinetobacter baumannii.

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    Singh, S; Zhang, Y Z; Chalkley, S; Ananthan, K; Demertzi, E; Beach, M; Cohen, M; Grover, V; Chung, C; Tatlock, J; Soni, N; Azadian, B

    2015-09-01

    Antibiotic use in intensive care units (ICUs) can promote antimicrobial resistance. Outbreaks of multi-resistant bacteria significantly affect patient outcomes and delivery of care. Antibiotic stewardship programmes (ASPs), combining root-cause analyses and multi-faceted prevention strategies, are necessary, often at significant cost and time. Which elements of such strategies have the largest impact on antibiotic usage following an outbreak is unclear. The aim of this study was to investigate how antibiotic usage in a university hospital ICU changed with a non-protocolised ASP following a disruptive outbreak of multi-resistant Acinetobacter baumannii (MRAB). This was a three time-period observational cohort study. The primary endpoint was the change in overall antibiotic usage (daily defined dose, DDD, antibiotic-days, antibiotic-courses) for consecutive ICU patients staying >48 h, over three 6-month study time periods pre-MRAB (2008, n = 84) and post-MRAB (2010, n = 88; 2012, n = 122). Secondary endpoints were changes in antibiotic usage and patient demographics, in predefined admission categories (Medical Emergency, ME; Surgical Elective, SEL; and Surgical Emergency, SE). The mean age (54.6 ± 17.7, 58.1 ± 17.9, 62.8 ± 19.1 years*) and severity of illness (APACHE 14.8 ± 8.0, 16.7 ± 6.8, 18.3 ± 6.1*) increased, particularly medical admissions. There was a sustained reduction in DDD antibiotic usage [1895.1 (2008), 1224.2 (2010), 1236.6 (2012) per 1000 patient-days] but no overall change in antibiotic-days or antibiotic-courses. Antibiotic usage (antibiotic-days) fell significantly in surgical emergency admissions [20.2 ± 32.1, 4.6 ± 7.4*, 5.9 ± 7.3]. There was a sustained drop in beta-lactam, quinolone, glycopeptide and macrolide usage. Following an MRAB outbreak, and subsequent operational changes including enhanced ASPs (non-protocolised), there was a sustained overall fall in antibiotic usage in spite of

  5. Microbiological methods for surveillance of carrier status of multiresistant bacteria.

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    Oteo, Jesús; Bou, Germán; Chaves, Fernando; Oliver, Antonio

    2017-12-01

    The presence of colonised patients is one of the main routes for the spread of multiresistant bacteria, and its containment is a clinical and public health priority. Surveillance studies are essential for early detection of colonisation by these bacteria. This article discusses the different microbiological methods, both based on culturing and molecular methods, for detection of carriers of multiresistant bacteria. Those species with a high clinical/epidemiological impact or generating therapeutic difficulties are included: Methicillin-resistant Staphylococcus aureus, Enterococcus spp. resistant to glycopeptides, enterobacteriaceae producing extended spectrum β-lactamases and plasmid-mediated AmpC, carbapenemases producing enterobacteriaceae, Acinetobacter baumannii and multiresistant Pseudomonas aeruginosa. The information in this document should be considered as a structure matrix to be tailored to the specific needs of each centre. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  6. Acinetobacter baumannii

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    Abdul Rasheed, Muzaheed; Alzahrani, Faisal Mousa; Sattar Shaikh, Saeed

    2017-01-01

    To identify the Acinetobacter baumannii infection among transfusion dependent thalassemia patients. A quantitative approach was employed to assess Acinetobacter baumannii infection in transfusion dependent thalassemia patients. Samples were collected from 916 patients, which have shown bacterial growth on MacConkey and blood agar culture media. A. baumannii strains were identified by microbiological methods and Gram's staining. API 20 E kit (Biomerieux, USA) was used for final identification. From 916 cultured blood specimens, 107 (11.6%) showed growth of A. baumannii . Serum ferritin in thalassemic patients without bacterial infections was 3849.5 ± 1513.5  µ g/L versus 6413.5 ± 2103.9  µ g/L in those with bacterial infections ( p = 0.0001). Acinetobacter baumannii infected patients have shown higher serum ferritin levels ( p = 0.0001). Serum ferritin in thalassemic patients was 3849.5 ± 1513.5  µ g/L versus 6413.5 ± 2103.9  µ g/L in those with bacterial infections ( p = 0.0001). Acinetobacter baumannii infected patients showed high serum ferritin levels ( p = 0.0001). The clinical symptoms have been found with A. baumannii +ve with a mean and standard deviation of 47 (5.1%) and A. baumannii -ve with mean and standard deviation of 60 (6.5%). Isolation of asymptomatic A. baumannii from the thalassemia patients shows an alarming situation of bacterial infections. A continuous surveillance of transfusion dependent thalassemia patients is recommended for bacterial sepsis.

  7. Antibacterial activity of the Antarctic bacterium Janthinobacterium sp. SMN 33.6 against multi-resistant Gram-negative bacteria

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    Geraldine Asencio

    2014-01-01

    Conclusions: The ethanolic extract of Janthinobacterium sp. SMN 33.6 possesses antibacterial activity against a chromosomal AmpC beta-lactamase-producing strain of Serratia marcescens, an extended-spectrum beta-lactamase-producing Escherichia coli and also against carbapenemase-producing strains of Acinetobacter baumannii and Pseudomonas aeruginosa. This becomes a potential and interesting biotechnological tool for the control of bacteria with multi-resistance to commonly used antibiotics.

  8. Epidemiology of multi-resistance Gram negative pathogen circulating in Liguria and molecular characterization of different carbapenemases

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    Erika Coppo

    2011-06-01

    Full Text Available This study was conducted during January-April 2010 with the collaboration of 7 clinical microbiology laboratories evenly distributed across the Ligurian area to identify the most frequent Gram negative species and to evaluate their antibiotic susceptibility patterns Overall, 110 consecutive multi-resistant non duplicate Gram negative isolates,were collected and sent to the coordinating laboratory (Sezione di Microbiologia del DISC, University of Genoa, Italy together with susceptibility data obtained by routine methods. In addition, strains resistant to carbapenems were characterized by PCR. A total of 110 Gram negative multi-resistance strains were found, including 74 and 36 isolated from healthcare or nosocomial settings and community acquired infections, respectively. The most represented pathogens were: A. baumannii (38, 34.5%, E. coli (30, 27.2%, P. aeruginosa (29, 26.3%, K. pneumoniae (9, 8.2% and P. mirabilis (4, 3.6%. A. baumannii were more frequently collected from healthcare settings or nosocomial samples, while the other strains were generally equally isolated from in- and out-patients. Amikacin was the most active molecule against E. coli and P. mirabilis (96,7% and 100% of susceptible stains respectively. Colistin was the only active molecule agains A. baumanii and P. aeruginosa (100% of susceptible strains. Against K. pneumoniae tigecycline and colistin were the most active molecules (100% of susceptible strains. Imipenem was the most active compound against E. coli and P. mirabilis (100% of susceptible strains. A large number (97.4% of A. baumannii was resistant to imipenem. K. pneumoniae and P. aeruginosa showed rates of resistance of 88% and 34.4% respectively. A. baumannii, K. pneumoniae and P. aeruginosa isolates resistant to Imipenem, carried OXA-23, KPC and VIM carbapenemases.These data shown a significant spread of multidrug-resistant Gram negative bacteria in hospitals and in communities.The production of carbapenemase in

  9. Identification of Acinetobacter baumannii via amplified ribosomal DNA restriction analysis

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    Delsuz Rezaei

    2014-02-01

    Full Text Available Background: Acinetobacter baumannii is a multi-resistant opportunistic nosocomial pathogen responsible for hospital outbreaks worldwide. In addition to common microscopic and biochemical methods, the Amplified Ribosomal DNA Restriction Analysis (ARDRA was tested to identify Acinetobacter genomic species (DNA groups. Methods: In this study, standard biochemical tests were used for identification of isolates. The genomic species of Acinetobacter spp. was confirmed by Amplified Ribosomal DNA Restriction Analysis (ARDRA. PCR products of 16S rRNA were digested with AluI, MboI and HhaI restriction enzymes. Results: ARDRA proved to be a rapid and reliable method for identification of Acinetobacter baumannii (genome species 2 of the Acinetobacter genomic species, including the closely related genomic species (genomic species 1 (A. calcoaceticus, 2 (A. baumannii, 3, and TU13. Conclusion: The results of this study suggested that ARDRA with AluI, MboI and HhaI restriction enzymes can be used for identificationof A. baumannii which may help to elucidate the ecology and clinical significance of different species of this genus. Since ARDRA is performed by universal primers of 16S rDNA gene, it is expected to be applicable to identifying most bacterial species.

  10. Investigation of colistin sensitivity via three different methods in Acinetobacter baumannii isolates with multiple antibiotic resistance.

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    Sinirtaş, Melda; Akalin, Halis; Gedikoğlu, Suna

    2009-09-01

    In recent years there has been an increase in life-threatening infections caused by Acinetobacter baumannii with multiple antibiotic resistance, which has lead to the use of polymyxins, especially colistin, being reconsidered. The aim of this study was to investigate the colistin sensitivity of A. baumannii isolates with multiple antibiotic resistance via different methods, and to evaluate the disk diffusion method for colistin against multi-resistant Acinetobacter isolates, in comparison to the E-test and Phoenix system. The study was carried out on 100 strains of A. baumannii (colonization or infection) isolated from the microbiological samples of different patients followed in the clinics and intensive care units of Uludağ University Medical School between the years 2004 and 2005. Strains were identified and characterized for their antibiotic sensitivity by Phoenix system (Becton Dickinson, Sparks, MD, USA). In all studied A. baumannii strains, susceptibility to colistin was determined to be 100% with the disk diffusion, E-test, and broth microdilution methods. Results of the E-test and broth microdilution method, which are accepted as reference methods, were found to be 100% consistent with the results of the disk diffusion tests; no very major or major error was identified upon comparison of the tests. The sensitivity and the positive predictive value of the disk diffusion method were found to be 100%. Colistin resistance in A. baumannii was not detected in our region, and disk diffusion method results are in accordance with those of E-test and broth microdilution methods.

  11. Epidemiology of Multiresistant Acinetobacter Infections in Bulgaria

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    Savov, E.; Borisova, M.; Michailova, G.

    2007-01-01

    Evolution of bacteria towards resistance to antimicrobial drugs, including these with multidrug resistance, is very important issue for hospital epidemiology in all over the world. There are many papers about an increasing number of Acinetobacter baumannii blood stream and other type of infections in patients at military medical facilities in the Iraq / Kuwait region and in Afghanistan during Operation Enduring Freedom /OEF /. It has now become also a one of the major cause of hospital acquired infections in Bulgaria which due to its remarkable propensity to rapidly acquire resistance determinants to a wide range of antimicrobial drugs. According to the data obtained in Bulgaria, it can be concluded that the majority of the A.baumannii isolates was strikingly resistant, including the 3rd generation of cephalosporins, quinolones and also carbapenems, in the last years. Different methods / phenotypical and molecular methods, including PCR/ for a multidrug A.baumannii investigation and its clonality determination are needed, especially when the strains are not epidemiological related.(author)

  12. Analysis of Acinetobacter baumannii resistance patterns in patients with chronic obstructive pulmonary disease (COPD in terms of choice of effective empiric antibiotic therapy

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    Aneta Grochowalska

    2017-06-01

    In the performed study, the infections caused by multi-resistant Acinetobacter baumannii, were observed in COPD, which should be taken into consideration in choosing empirical antibiotic therapy. Simultaneously, the local resistance patterns of multi-drug-resistant (MDR Gram-negative strains co-infecting COPD should be considered in empirical treatment. Moreover, both additional clinical complication and co-infections contribute to a more severe course of diseases. In this study, the mortality percent exceeded 29%.

  13. Patients hospitalized abroad as importers of multiresistant bacteria-a cross-sectional study.

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    Khawaja, T; Kirveskari, J; Johansson, S; Väisänen, J; Djupsjöbacka, A; Nevalainen, A; Kantele, A

    2017-09-01

    The pandemic spread of multidrug-resistant (MDR) bacteria poses a threat to healthcare worldwide, with highest prevalence in indigent regions of the (sub)tropics. As hospitalization constitutes a major risk factor for colonization, infection control management in low-prevalence countries urgently needs background data on patients hospitalized abroad. We collected data on 1122 patients who, after hospitalization abroad, were treated at the Helsinki University Hospital between 2010 and 2013. They were screened for methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE), vancomycin-resistant enterococci, carbapenemase-producing Enterobacteriaceae (CPE), multiresistant Pseudomonas aeruginosa and multiresistant Acinetobacter baumannii. Risk factors for colonization were explored by multivariate analysis. MDR colonization rates were higher for those hospitalized in the (sub)tropics (55%; 208/377) compared with temperate zones (17%; 125/745). For ESBL-PE the percentages were 50% (190/377) versus 12% (92/745), CPE 3.2% (12/377) versus 0.4% (3/745) and MRSA 6.6% (25/377) versus 2.4% (18/745). Colonization rates proved highest in those returning from South Asia (77.6%; 38/49), followed by those having visited Latin America (60%; 9/16), Africa (60%; 15/25) and East and Southeast Asia (52.5%; 94/179). Destination, interhospital transfer, short time interval to hospitalization, young age, surgical intervention, residence abroad, visiting friends and relatives, and antimicrobial use proved independent risk factors for colonization. Post-hospitalization colonization rates proved higher in the (sub)tropics than elsewhere; 11% (38/333) of carriers developed an MDR infection. We identified several independent risk factors for contracting MDR bacteria. The data provide a basis for infection control guidelines in low-prevalence countries. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  14. Tn7::In2-8 dispersion in multidrug resistant isolates of Acinetobacter baumannii from Chile Dispersión de Tn7::In2-8 en aislamientos multirresistentes de Acinetobacter baumannii de Chile

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    M. S. Ramírez

    2010-06-01

    Full Text Available Acinetobacter baumannii is considered an important pathogen in our hospital environment having a well-known capacity to acquire different mechanisms of antibiotic resistance. Previous studies in our laboratory had exposed the high dispersion of class 2 integrons in this species. In the present study, we analyzed 7 multiresistant intI2 positive A. baumannii isolates, 6 of which were found to harbour the Tn7::In2-8 element. Our results demonstrate the unusually high distribution of Tn7::In2-8 among different A. baumannii clones from Chile, suggesting a particular behavior of these elements at geographical level.Acinetobacter baumannii, patógeno de importancia clínica en el ámbito hospitalario, es reconocido como un microorganismo que posee la capacidad de evolucionar rápidamente hacia la multirresistencia. Estudios previos efectuados en nuestro laboratorio han demostrado la alta dispersión de los integrones de clase 2 en aislamientos de esta especie. En el presente trabajo se analizaron 7 aislamientos de Acinetobacter baumannii multirresistentes portadores de la integrasa de clase 2, 6 de los cuales portaban el inusual arreglo Tn7::In2-8. Nuestros resultados muestran una elevada frecuencia de dispersión del elemento Tn7::In2-8 en diferentes clones circulantes en Chile, lo que sugiere un comportamiento geográfico particular.

  15. Containment of a multiresistant Serratia marcescens outbreak.

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    Edgar, P; Mlcak, R; Desai, M; Linares, H A; Phillips, L G; Heggers, J P

    1997-02-01

    A 3-year-old male from Bolivia who sustained a full-thickness 80 per cent TBSA burn complicated by smoke inhalation on the 28 March 1995 was admitted to our burn centre on 6 April 1995. On 11 April the patient's wounds were colonized with a Serratia marcescens sensitive only to ciprofloxacin and imipenem. Sputum cultures revealed the same phenotypic S. marcescens. Two patients who were admitted days later had the same phenotypic S. marcescens. Their TBSA burns ranged from 54 to 80 per cent. Both were injured in early April. Sputum and wound cultures were also positive for S. marcescens. Precautionary measures were instituted immediately. All potential reservoirs were cultured. Cultures were negative for S. marcescens. Patient therapy was maintained via strict isolation. The first patient died on 17 May. The two remaining patients survived and were discharged colonized with S. marcescens. However, the biotype of the initial S. marcescens was different from the latter two. Early recognition of a multiresistant S. marcescens resulted in negating the spread of this agent to other patients.

  16. Acinetobacter baumannii in intensive care unit: A novel system to study clonal relationship among the isolates

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    Leonardis Francesca

    2008-06-01

    Full Text Available Abstract Background The nosocomial infections surveillance system must be strongly effective especially in highly critic areas, such as Intensive Care Units (ICU. These areas are frequently an epidemiological epicentre for transmission of multi-resistant pathogens, like Acinetobacter baumannii. As an epidemic outbreak occurs it is very important to confirm or exclude the genetic relationship among the isolates in a short time. There are several molecular typing systems used with this aim. The Repetitive sequence-based PCR (REP-PCR has been recognized as an effective method and it was recently adapted to an automated format known as the DiversiLab system. Methods In the present study we have evaluated the combination of a newly introduced software package for the control of hospital infection (VIGI@ct with the DiversiLab system. In order to evaluate the reliability of the DiversiLab its results were also compared with those obtained using f-AFLP. Results The combination of VIGI@ct and DiversiLab enabled an earlier identification of an A. baumannii epidemic cluster, through the confirmation of the genetic relationship among the isolates. This cluster regards 56 multi-drug-resistant A. baumannii isolates from several specimens collected from 13 different patients admitted to the ICU in a ten month period. The A. baumannii isolates were clonally related being their similarity included between 97 and 100%. The results of the DiversiLab were confirmed by f-AFLP analysis. Conclusion The early identification of the outbreak has led to the prompt application of operative procedures and precautions to avoid the spread of pathogen. To date, 6 months after the last A. baumannii isolate, no other related case has been identified.

  17. Complexity of Complement Resistance Factors Expressed by Acinetobacter baumannii Needed for Survival in Human Serum.

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    Sanchez-Larrayoz, Amaro F; Elhosseiny, Noha M; Chevrette, Marc G; Fu, Yang; Giunta, Peter; Spallanzani, Raúl G; Ravi, Keerthikka; Pier, Gerald B; Lory, Stephen; Maira-Litrán, Tomás

    2017-10-15

    Acinetobacter baumannii is a bacterial pathogen with increasing impact in healthcare settings, due in part to this organism's resistance to many antimicrobial agents, with pneumonia and bacteremia as the most common manifestations of disease. A significant proportion of clinically relevant A. baumannii strains are resistant to killing by normal human serum (NHS), an observation supported in this study by showing that 12 out of 15 genetically diverse strains of A. baumannii are resistant to NHS killing. To expand our understanding of the genetic basis of A. baumannii serum resistance, a transposon (Tn) sequencing (Tn-seq) approach was used to identify genes contributing to this trait. An ordered Tn library in strain AB5075 with insertions in every nonessential gene was subjected to selection in NHS. We identified 50 genes essential for the survival of A. baumannii in NHS, including already known serum resistance factors, and many novel genes not previously associated with serum resistance. This latter group included the maintenance of lipid asymmetry genetic pathway as a key determinant in protecting A. baumannii from the bactericidal activity of NHS via the alternative complement pathway. Follow-up studies validated the role of eight additional genes identified by Tn-seq in A. baumannii resistance to killing by NHS but not by normal mouse serum, highlighting the human species specificity of A. baumannii serum resistance. The identification of a large number of genes essential for serum resistance in A. baumannii indicates the degree of complexity needed for this phenotype, which might reflect a general pattern that pathogens rely on to cause serious infections. Copyright © 2017 by The American Association of Immunologists, Inc.

  18. Extremely high prevalence of multi-resistance among uropathogens ...

    African Journals Online (AJOL)

    Extremely high prevalence of multi-resistance among uropathogens from hospitalised children in Beira, Mozambique. BT van der Meeren, KD Chhaganlal, A Pfeiffer, E Gomez, JJ Ferro, M Hilbink, C Macome, FJ van der Vondervoort, K Steidel, PC Wever ...

  19. Rapid molecular characterization of Acinetobacter baumannii clones with rep-PCR and evaluation of carbapenemase genes by new multiplex PCR in Hospital District of Helsinki and Uusimaa.

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    Tanja Pasanen

    Full Text Available Multidrug-resistant Acinetobacter baumannii (MDRAB is an increasing problem worldwide. Prevalence of carbapenem resistance in Acinetobacter spp. due to acquired carbapenemase genes is not known in Finland. The purpose of this study was to examine prevalence and clonal spread of multiresistant A. baumannii group species, and their carbapenemase genes. A total of 55 Acinetobacter isolates were evaluated with repetitive PCR (DiversiLab to analyse clonality of isolates, in conjunction with antimicrobial susceptibility profile for ampicillin/sulbactam, colistin, imipenem, meropenem, rifampicin and tigecycline. In addition, a new real-time PCR assay, detecting most clinically important carbapenemase genes just in two multiplex reactions, was developed. The assay detects genes for KPC, VIM, IMP, GES-1/-10, OXA-48, NDM, GIM-1, SPM-1, IMI/NMC-A, SME, CMY-10, SFC-1, SIM-1, OXA-23-like, OXA-24/40-like, OXA-58 and ISAbaI-OXA-51-like junction, and allows confident detection of isolates harbouring acquired carbapenemase genes. There was a time-dependent, clonal spread of multiresistant A. baumannii strongly correlating with carbapenamase gene profile, at least in this geographically restricted study material. The new carbapenemase screening assay was able to detect all the genes correctly suggesting it might be suitable for epidemiologic screening purposes in clinical laboratories.

  20. Clonal relatedness and biofilm formation of OXA-23-producing carbapenem resistant Acinetobacter baumannii isolates from hospital environment.

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    Aliramezani, Amir; Douraghi, Masoumeh; Hajihasani, Azade; Mohammadzadeh, Mona; Rahbar, Mohammad

    2016-10-01

    Carbapenem-resistant Acinetobacter baumannii (CRAB) is a serious threat for hospitalized patients and it can survive for long periods in hospital settings, particularly on inanimate surfaces. The environment occupied by these resistant and resilient isolates may act as a reservoir for cross-colonization and outbreaks. Here, we aimed to determine the distribution of CRAB in the hospital environment and to characterize their clonal relatedness, susceptibility profile, carriage of bla OXA genes, and biofilm formation. A total of 1080 samples were collected from various environmental surfaces and equipment of two referral hospitals in Tehran, Iran. The A. baumannii isolates were subjected to gyrB multiplex PCR, antibiotic susceptibility testing, biofilm formation assay, pulsed field gel electrophoresis (PFGE), and multiplex PCR for bla OXA-58 , bla OXA-24 , and bla OXA-23 genes. Eighteen Acinetobacter spp. were isolated; 8 were identified as A. baumannii and 10 as A. lwoffii. Five of A. baumannii isolates were CRAB and exhibited the multidrug-resistant (MDR) phenotype as well. All CRAB isolates produced biofilm, albeit with different levels. Four of CRAB isolates harbored the bla OXA-23 . The CRAB isolates were clustered into 3 distinct pulsotypes (PTs). The CRAB isolates belonging to PT1 were detected in two geographically distinct hospitals whereas those belonging to PT3 were found in two different units of same hospital. This study revealed the presence of clonally related OXA-23-producing CRAB in high risk units of referral hospitals as inter- or intra-hospital dissemination. The distribution of multiresistant A. baumannii on several surfaces and areas may increase the risk of transmission of resistant isolates to vulnerable patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Analysis of Acinetobacter baumannii resistance patterns in patients with chronic obstructive pulmonary disease (COPD) in terms of choice of effective empiric antibiotic therapy.

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    Grochowalska, Aneta; Kozioł-Montewka, Maria; Sobieszczańska, Anna

    2017-06-12

    Introduction. Multi-resistant Acinetobacter baumannii isolated from patients has become one of the most hazardous pathogens in health care settings. The aim of the study was to analyze pneumonia caused by Acinetobacter baumannii in patients hospitalized because of exacerbation of chronic obstructive pulmonary diseases (COPD), who were admitted to the Pulmonology Ward of the Masovian Specialistic Hospital in Radom (MSS). The incidence and drug sensitivity of these non-fermenting rods were evaluated, and compliance with antimicrobial procedure with the algorithm of the guidelines in applicable recommendations, was estimated. This should result in determining the local patterns of resistance and verifying therapeutic procedures in accordance with the assumptions of hospital antibiotic policy. In addition, the study examined the effectiveness of empiric and targeted therapy according to the clinical condition of the patient, and the eradication of A. baumannii, in comparison with the aggravating factors of the patient. Materials and Method. The retrospective study included 90 patients with exacerbation of COPD whose etiological factor of infection was A. baumannii, hospitalized in the Department of Pulmonology (MSS) in 2012-2016. Results. Studies were conducted on 90 patients with COPD exacerbation from which A. baumannii was isolated. Co-infections with other bacterial species among 41 patients were additionally noted. The majority of A. baumannii strains showed a high resistance (90%) to fluoroquinolones, ceftazidime, piperacillin/tazobactam. For strains causing a co-infection, drug resistance was successively 44-56%, 44%, 44%. All of patients received empirical therapy. The most commonly used drug was amoxicillin with a clavulanic acid, often combined with fluoroquinolone. This type of therapy was effective among 10% of patients. The mortality in this group was determined at 29%. Among 79% of patients with COPD, a targeted therapy was performed which proved to be

  2. Antibacterial activity of the essential oil of Origanum vulgare L. (Lamiaceae against bacterial multiresistant strains isolated from nosocomial patients

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    Adalberto Coelho da Costa

    Full Text Available Antibiotics are considered the main therapeutic option to treat bacterial infections; however, there is the disadvantage of increasing bacterial resistance. Thus, the research of antimicrobials of plant origin has been an important alternative. This work aimed at determining the in vitro antibacterial activity of the essential oil of Origanum vulgare L. (Lamiaceae on multiresistant bacteria isolated from biological materials. 24 strains of nosocomial bacteria were used and divided into six different species that were inhibited by the essential oil in the preliminary "screening" which was accomplished by the diffusion technique in agar. MIC was determined by the microdilution method, beginning with solutions with the final concentrations: 8 up to 0.125% with the following results: The four samples (100% of Escherichia coli, Enterococcus faecalis and MRSA were inhibited by the essential oil at the concentration of 0.125%. Three samples (75% of Acinetobacter baumannii at 0.125% and a sample (25% at 0.5%; Klebsiella pneumoniae (75% at 0.125% and 25% at 0.25%; Pseudomonas aeruginosa (75% at 0.5% and 25% at 0.25%. MIC varied from 78 to 83%. It was concluded through the obtained data that there was not difference in the minimum bactericidal concentration (0.5% of the referred oil for Gram positive as well for Gram negative microorganisms.

  3. Mutations in the β-Subunit of the RNA Polymerase Impair the Surface-Associated Motility and Virulence of Acinetobacter baumannii.

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    Pérez-Varela, María; Corral, Jordi; Vallejo, Juan Andrés; Rumbo-Feal, Soraya; Bou, Germán; Aranda, Jesús; Barbé, Jordi

    2017-08-01

    Acinetobacter baumannii is a major cause of antibiotic-resistant nosocomial infections worldwide. In this study, several rifampin-resistant spontaneous mutants obtained from the A. baumannii ATCC 17978 strain that differed in their point mutations in the rpoB gene, encoding the β-subunit of the RNA polymerase, were isolated. All the mutants harboring amino acid substitutions in position 522 or 540 of the RpoB protein were impaired in surface-associated motility and had attenuated virulence in the fertility model of Caenorhabditis elegans The transcriptional profile of these mutants included six downregulated genes encoding proteins homologous to transporters and metabolic enzymes widespread among A. baumannii clinical isolates. The construction of knockout mutants in each of the six downregulated genes revealed a significant reduction in the surface-associated motility and virulence of four of them in the A. baumannii ATCC 17978 strain, as well as in the virulent clinical isolate MAR002. Taken together, our results provide strong evidence of the connection between motility and virulence in this multiresistant nosocomial pathogen. Copyright © 2017 American Society for Microbiology.

  4. First report on blaNDM-1-producing Acinetobacter baumannii in three clinical isolates from Ethiopia.

    Science.gov (United States)

    Pritsch, Michael; Zeynudin, Ahmed; Messerer, Maxim; Baumer, Simon; Liegl, Gabriele; Schubert, Soeren; Löscher, Thomas; Hoelscher, Michael; Belachew, Tefara; Rachow, Andrea; Wieser, Andreas

    2017-03-01

    Multidrug-resistant Gram-negative bacterial infections are recognized as one of the major threats to global health. In this study, we describe for the first time bla NDM-1 gene carrying organisms from Ethiopia consisting of three Acinetobacter baumannii isolates from patients in Jimma. Besides phenotypic antimicrobial susceptibility testing, molecular strain typing and sequencing was performed to describe the phylogenetic relation of the Ethiopian isolates in detail in relation to published isolates from all over the globe. Three multi-resistant, bla NDM-1 -positive Acinetobacter baumannii isolates, most likely a local clonal diffusion, were isolated. Two of the three isolates described within this study were untreatable with the locally available antimicrobials and were only susceptible to polymyxin B and amikacin. The genome sequences confirmed the isolates to be distinct from the outbreak strains reported from Kenya, the only other characterized bla NDM-1 positive Acinetobacter baumannii strains in East Africa so far. Up to date, no other bacterial species were found to harbour the gene cassette in Jimma and conjugation to E. coli was not successful under laboratory conditions. However, natural transmission to other bacteria seems likely, given the evident lack of hygienic precautions due to limited resource settings. The detected isolates could solely be the tip of the iceberg regarding the presence of NDM-1 producing organisms in the region, as only a limited number of bacterial isolates were evaluated so far and until recently, susceptibility testing and isolation of bacteria could hardly be performed in clinical patient care. These multi-drug resistant organisms pose a serious threat to antimicrobial treatments in Jimma, Ethiopia.

  5. Reservoirs of Non-baumannii Acinetobacter Species

    Science.gov (United States)

    Al Atrouni, Ahmad; Joly-Guillou, Marie-Laure; Hamze, Monzer; Kempf, Marie

    2016-01-01

    Acinetobacter spp. are ubiquitous gram negative and non-fermenting coccobacilli that have the ability to occupy several ecological niches including environment, animals and human. Among the different species, Acinetobacter baumannii has evolved as global pathogen causing wide range of infection. Since the implementation of molecular techniques, the habitat and the role of non-baumannii Acinetobacter in human infection have been elucidated. In addition, several new species have been described. In the present review, we summarize the recent data about the natural reservoir of non-baumannii Acinetobacter including the novel species that have been described for the first time from environmental sources and reported during the last years. PMID:26870013

  6. Contribution of efflux pumps, porins, and β-lactamases to multidrug resistance in clinical isolates of Acinetobacter baumannii.

    Science.gov (United States)

    Rumbo, C; Gato, E; López, M; Ruiz de Alegría, C; Fernández-Cuenca, F; Martínez-Martínez, L; Vila, J; Pachón, J; Cisneros, J M; Rodríguez-Baño, J; Pascual, A; Bou, G; Tomás, M

    2013-11-01

    We investigated the mechanisms of resistance to carbapenems, aminoglycosides, glycylcyclines, tetracyclines, and quinolones in 90 multiresistant clinical strains of Acinetobacter baumannii isolated from two genetically unrelated A. baumannii clones: clone PFGE-ROC-1 (53 strains producing the OXA-58 β-lactamase enzyme and 18 strains with the OXA-24 β-lactamase) and clone PFGE-HUI-1 (19 strains susceptible to carbapenems). We used real-time reverse transcriptase PCR to correlate antimicrobial resistance (MICs) with expression of genes encoding chromosomal β-lactamases (AmpC and OXA-51), porins (OmpA, CarO, Omp33, Dcap-like, OprB, Omp25, OprC, OprD, and OmpW), and proteins integral to six efflux systems (AdeABC, AdeIJK, AdeFGH, CraA, AbeM, and AmvA). Overexpression of the AdeABC system (level of expression relative to that by A. baumannii ATCC 17978, 30- to 45-fold) was significantly associated with resistance to tigecycline, minocycline, and gentamicin and other biological functions. However, hyperexpression of the AdeIJK efflux pump (level of expression relative to that by A. baumannii ATCC 17978, 8- to 10-fold) was significantly associated only with resistance to tigecycline and minocycline (to which the TetB efflux system also contributed). TetB and TetA(39) efflux pumps were detected in clinical strains and were associated with resistance to tetracyclines and doxycycline. The absence of the AdeABC system and the lack of expression of other mechanisms suggest that tigecycline-resistant strains of the PFGE-HUI-1 clone may be associated with a novel resistance-nodulation-cell efflux pump (decreased MICs in the presence of the inhibitor Phe-Arg β-naphthylamide dihydrochloride) and the TetA(39) system.

  7. [Presence of resistance factors to antibiotics in multiresistant enterobacteria].

    Science.gov (United States)

    Parada, J L; De Nardo, J; Rebollo, M; Marcenac, F; Fernández, A

    1977-01-01

    The present study was carried out with 111 multiresistant pathogenic strains of enterobacterias isolated from different sources with increased resistance to three or more antibiotics. Among the identified species are included E. coli, Shigella sp., Salmonella oranienburg, Klebsiella pneumoniae and Citrobacter freundii. In general, the minimal inhibitory concentration of antibiotics was above 100 microgram/ml and in some cases it was superior to 1000 microgram/ml. Resistance transfer factors were detected in 72% of the strains; 33% movilized the complete pattern of resistance and 67% did it partially because some of the determinants were not transfered. The Citrobacter strains show a high frequency of transference (10(-1)), while for the others species it was in the order of 10(-2)--10(-3). The use of a multi-inoculator allows to perform in a simple way the preliminar evaluation about the presence or absence of R transfer factors in multiresistant strains. This technique has shown good correlation with the data obtained by the usual dilution and plating method.

  8. OXA-Carbapenemases Present in Clinical Acinetobacter baumannii-calcoaceticus Complex Isolates from Patients in Kurdistan Region, Iraq.

    Science.gov (United States)

    Ganjo, Aryann R; Maghdid, Delshad M; Mansoor, Isam Y; Kok, Dik J; Severin, Juliette A; Verbrugh, Henri A; Kreft, Deborah; Fatah, M H; Alnakshabandi, A A; Dlnya, Asad; Hammerum, Anette M; Ng, Kim; Goessens, Wil

    2016-12-01

    In addition to intrinsic resistance in Acinetobacter baumannii, many different types of acquired resistance mechanisms have been reported, including the presence of VIM and IMP metallo β-lactamases and also of bla OXA-23-like and bla OXA-58-like enzymes. In the Kurdistan region of Iraq, the multiresistant A. baumannii-calcoaceticus complex is prevalent. We characterized the different mechanisms of resistance present in clinical isolates collected from different wards and different hospitals from the Kurdistan region. One hundred twenty clinical nonduplicate A. baumannii-calcoaceticus complex isolates were collected from four hospitals between January 2012 and October 2013. The identification of the isolates was confirmed by MALDI-TOF. The susceptibility to different antibiotics was determined by disk diffusion and analyzed in accordance to EUCAST guidelines. By PCR, the presence of bla OXA-51-like , bla OXA-23-like , bla OXA-24-like , and bla OXA-58-like genes was determined as well as the presence of the insertion element ISAba1. Clonal diversity was analyzed by pulsed-field gel electrophoresis (PFGE) using the restriction enzyme ApaI and, in addition, multilocus sequence typing (MLST) was performed on a selected subset of 15 isolates. All 120 A. baumannii isolates harbored bla OXA-51-like genes. One hundred one out of 110 (92%) imipenem (IMP)-resistant A. baumannii-calcoaceticus complex isolates additionally carried the bla OXA-23-like gene and four isolates (3%) were positive for bla OXA-24-like. All 101 bla OXA-23-like -positive isolates had the ISAba1 insertion sequence, 1,600 bp upstream of the bla OXA-23-like gene. The bla OXA-58-like gene was not detected in any of the 110 IMP-resistant strains. Eight different PFGE clusters were identified and distributed over the different hospitals. MLST analysis performed on a subset of 15 representative isolates revealed the presence of the international clone ST2 (Pasteur). Besides ST2 (Pasteur), also many other

  9. Iron and Acinetobacter baumannii Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Valentina Gentile

    2014-08-01

    Full Text Available Acinetobacter baumannii is an emerging nosocomial pathogen, responsible for infection outbreaks worldwide. The pathogenicity of this bacterium is mainly due to its multidrug-resistance and ability to form biofilm on abiotic surfaces, which facilitate long-term persistence in the hospital setting. Given the crucial role of iron in A. baumannii nutrition and pathogenicity, iron metabolism has been considered as a possible target for chelation-based antibacterial chemotherapy. In this study, we investigated the effect of iron restriction on A. baumannii growth and biofilm formation using different iron chelators and culture conditions. We report substantial inter-strain variability and growth medium-dependence for biofilm formation by A. baumannii isolates from veterinary and clinical sources. Neither planktonic nor biofilm growth of A. baumannii was affected by exogenous chelators. Biofilm formation was either stimulated by iron or not responsive to iron in the majority of isolates tested, indicating that iron starvation is not sensed as an overall biofilm-inducing stimulus by A. baumannii. The impressive iron withholding capacity of this bacterium should be taken into account for future development of chelation-based antimicrobial and anti-biofilm therapies.

  10. In vitro activity of tigecycline against clinical isolates of carbapenem resistant Acinetobacter baumannii complex in Pretoria, South Africa

    Directory of Open Access Journals (Sweden)

    Ahmed Nahid H

    2012-05-01

    Full Text Available Abstract Background The presence of multi-drug resistant Acinetobacter baumannii raises a big therapeutic challenge in our hospital. Tigecycline, a new glycylcycline with expanded broad spectrum of activity against multi-drug resistant organisms was recently licensed in South Africa. Aim The aim of this study was to evaluate the in vitro activity of tigecycline against carbapenem resistant A. baumannii complex. Methods Consecutive clinical isolates of carbapenem resistant A. baumannii complex were collected between February and July 2010. Species identification and susceptibility testing was performed by Vitek-2 colorimetric compact system with Advanced Expert System (AES. Strains were tested for carbapenemase production by the modified Hodge test, according to the Clinical and Laboratory Standards Institute (CLSI guidelines. Results A total of 232 carbapenem resistant clinical isolates of A. baumannii complex were collected over the six months study period; 217 (93.5% of these were modified Hodge test positive. All isolates were susceptible to colistin and 174 (78% susceptible to amikacin whilst 20 (9% were susceptible to ciprofloxacin. For tigecycline 169 (75.8% were fully susceptible, 37 (16.6% intermediately resistant and only 17 (7.6% were fully resistant. None of the carbapenem resistant isolates were susceptible to ampicillin, amoxicillin/clavullanic acid, piperacillin/tazobactam, cefuroxime, cefuroxime axetil, cefoxitin, cefepime or nitrofurantoin. Conclusion All carbapenem resistant isolates were found to be fully susceptible to colistin; amikacin and tigecycline susceptibility was 78% and 76% respectively. Treatment options for infections due to carbapenem and multi-drug resistant A. baumannii organisms are limited and hence tigecycline and amikacin may be considered. The properties of tigecycline i.e. stability, safety, low toxicity, non cross-resistance with other antibiotics and its efficacy against multi-drug resistant A. baumannii

  11. In vitro activity of tigecycline against clinical isolates of carbapenem resistant Acinetobacter baumannii complex in Pretoria, South Africa.

    Science.gov (United States)

    Ahmed, Nahid H; Baba, Kamaldeen; Clay, Cornelis; Lekalakala, Ruth; Hoosen, Anwar A

    2012-05-03

    The presence of multi-drug resistant Acinetobacter baumannii raises a big therapeutic challenge in our hospital. Tigecycline, a new glycylcycline with expanded broad spectrum of activity against multi-drug resistant organisms was recently licensed in South Africa. The aim of this study was to evaluate the in vitro activity of tigecycline against carbapenem resistant A. baumannii complex. Consecutive clinical isolates of carbapenem resistant A. baumannii complex were collected between February and July 2010. Species identification and susceptibility testing was performed by Vitek-2 colorimetric compact system with Advanced Expert System (AES). Strains were tested for carbapenemase production by the modified Hodge test, according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. A total of 232 carbapenem resistant clinical isolates of A. baumannii complex were collected over the six months study period; 217 (93.5%) of these were modified Hodge test positive. All isolates were susceptible to colistin and 174 (78%) susceptible to amikacin whilst 20 (9%) were susceptible to ciprofloxacin. For tigecycline 169 (75.8%) were fully susceptible, 37 (16.6%) intermediately resistant and only 17 (7.6%) were fully resistant. None of the carbapenem resistant isolates were susceptible to ampicillin, amoxicillin/clavullanic acid, piperacillin/tazobactam, cefuroxime, cefuroxime axetil, cefoxitin, cefepime or nitrofurantoin. All carbapenem resistant isolates were found to be fully susceptible to colistin; amikacin and tigecycline susceptibility was 78% and 76% respectively. Treatment options for infections due to carbapenem and multi-drug resistant A. baumannii organisms are limited and hence tigecycline and amikacin may be considered. The properties of tigecycline i.e. stability, safety, low toxicity, non cross-resistance with other antibiotics and its efficacy against multi-drug resistant A. baumannii isolates make it a good choice. However, ongoing monitoring of

  12. Heteroresistance to Colistin in Multidrug-Resistant Acinetobacter baumannii

    OpenAIRE

    Li, Jian; Rayner, Craig R.; Nation, Roger L.; Owen, Roxanne J.; Spelman, Denis; Tan, Kar Eng; Liolios, Lisa

    2006-01-01

    Multidrug-resistant Acinetobacter baumannii has emerged as a significant clinical problem worldwide and colistin is being used increasingly as “salvage” therapy. MICs of colistin against A. baumannii indicate its significant activity. However, resistance to colistin in A. baumannii has been reported recently. Clonotypes of 16 clinical A. baumannii isolates and ATCC 19606 were determined by pulsed-field gel electrophoresis (PFGE), and colistin MICs were measured. The time-kill kinetics of coli...

  13. [Ceftaroline, a new broad-spectrum cephalosporin in the era of multiresistance].

    Science.gov (United States)

    Horcajada, Juan Pablo; Cantón, Rafael

    2014-03-01

    Antimicrobial resistance has increased during the last few years, representing a public health concern. Among Gram-positive organisms, methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae are paradigms of resistance and of the dispersion of multiresistant clones. Ceftaroline, a broad-spectrum cephalosporin that includes MRSA and penicillin-resistant S. pneumoniae, is the first β-lactam antibiotic useful in infections due to MRSA. Phase-III clinical trials have demonstrated its efficacy in the treatment of community-acquired pneumonia and in skin and soft tissue infections, which are the current indications for ceftaroline. Due to its microbiological and pharmacological (PK/PD) profiles, these indications could be expanded to include bacteremia, endocarditis, and even osteoarticular infections. Another notable feature is the activity of this drug against Gram-negative bacilli susceptible to third generation cephalosporins, indicating that ceftaroline could be useful when these organisms are suspected or demonstrated in polymicrobial infections. Clinical follow-up of ceftaroline use will more clearly define future ceftaroline indications. Copyright © 2014 Elsevier España, S.L. All rights reserved.

  14. A Pathogenic Potential of Acinetobacter baumannii-Derived Membrane Vesicles

    Directory of Open Access Journals (Sweden)

    Jong Suk Jin

    2011-12-01

    Full Text Available Acinetobacter baumannii secretes outer membrane vesicles (OMVs. A. baumannii OMVs deliver many virulence factors to host cells and then induce cytotoxicity and innate immune response. OMVs secreted from bacteria contribute directly to host pathology during A. baumannii infection.

  15. Molecular mechanisms associated with nosocomial carbapenem-resistant Acinetobacter baumannii in Mexico.

    Science.gov (United States)

    Alcántar-Curiel, María Dolores; García-Torres, Luis Francisco; González-Chávez, María Inés; Morfín-Otero, Rayo; Gayosso-Vázquez, Catalina; Jarillo-Quijada, Ma Dolores; Fernández-Vázquez, José Luis; Giono-Cerezo, Silvia; Rodríguez-Noriega, Eduardo; Santos-Preciado, José Ignacio

    2014-10-01

    Acinetobacter baumannii is an emerging pathogen worldwide that is most commonly associated with nosocomial infections and multi-drug resistance. In the present study we determined the mechanisms of carbapenem resistance and clonal diversity of A. baumannii nosocomial isolates in Hospital Civil de Guadalajara, Mexico. A total of 303 clinical isolates of A. baumannii identified during a period expanding from 2004-2011 were analyzed for carbapenem resistance using several microbiological and molecular methods. Clonal relatedness of these isolates was determined using pulsed-field gel electrophoresis. Of the 303 isolates, 84% were resistant to meropenem, 71.3% to imipenem and 78.3% the resistant isolates were positive for metallo-β-lactamases as determined by the phenotypic assay. In addition, 49.6% of carbapenem-intermediate or -resistant isolates carried the blaOXA-72 gene and 1.2% carried the blaVIM-1 gene. Efflux pump phenotype was responsible for reduced susceptibility to meropenem in 14.5% and to imipenem in 31.6% of the resistant isolates, respectively in the presence of the efflux pump inhibitor, carbonyl cyanide 3-chlorophenylhydrazone. Strains representing different carbapenem-resistant patterns exhibited reduced expression of 22, 29, 33, and 43 kDa OMPs. Among the bacterial collection studied, 48 different clones were identified, two of which were predominant and persistently transmitted. Carbapenemase production in combination with efflux pump expression, reduction in OMPs expression and the cross-transmission of clones appear to be major contributors to the high frequency of carbapenem-resistance observed in A. baumannii. To our knowledge, this is the first study to define the molecular mechanisms associated with carbapenem-resistance in A. baumannii in Mexico. Copyright © 2014 IMSS. Published by Elsevier Inc. All rights reserved.

  16. Resistance Markers and Genetic Diversity in Acinetobacter baumannii Strains Recovered from Nosocomial Bloodstream Infections

    Directory of Open Access Journals (Sweden)

    Hanoch S. I. Martins

    2014-01-01

    Full Text Available In this study, phenotypic and genotypic methods were used to detect metallo-β-lactamases, cephalosporinases and oxacillinases and to assess genetic diversity among 64 multiresistant Acinetobacter baumannii strains recovered from blood cultures in five different hospitals in Brazil from December 2008 to June 2009. High rates of resistance to imipenem (93.75% and polymyxin B (39.06% were observed using the disk diffusion (DD method and by determining the minimum inhibitory concentration (MIC. Using the disk approximation method, thirty-nine strains (60.9% were phenotypically positive for class D enzymes, and 51 strains (79.6% were positive for cephalosporinase (AmpC. Using the E-test, 60 strains (93.75% were positive for metallo-β-lactamases (MβLs. All strains were positive for at least one of the 10 studied genes; 59 (92.1% contained blaVIM-1, 79.6% contained blaAmpC, 93.7% contained blaOXA23 and 84.3% contained blaOXA51. Enterobacteria Repetitive Intergenic Consensus (ERIC-PCR analysis revealed a predominance of certain clones that differed from each other. However, the same band pattern was observed in samples from the different hospitals studied, demonstrating correlation between the genotypic and phenotypic results. Thus, ERIC-PCR is an appropriate method for rapidly clustering genetically related isolates. These results suggest that defined clonal clusters are circulating within the studied hospitals. These results also show that the prevalence of MDR A. baumannii may vary among clones disseminated in specific hospitals, and they emphasize the importance of adhering to appropriate infection control measures.

  17. Fatal nocardiosis in a dog caused by multiresistant Nocardia veterana.

    Science.gov (United States)

    Uhde, Ann-Kathrin; Kilwinski, Jochen; Peters, Martin; Verspohl, Jutta; Feßler, Andrea T; Schwarz, Stefan; Wohlsein, Peter

    2016-02-01

    Among pathogenic Nocardia species in humans and animals, infections caused by Nocardia (N.) veterana have rarely been described and so far, all non-human cases are linked to bovine mastitis in Brazil. The aim of this study was to identify the causative microorganism involved in the death of a three-month-old dog suffering from dyspnea and neurological deficits ante mortem. Pathomorphological investigation revealed (pyo-)granulomatous lesions in various organs. Bacteriological examination was performed and the respective bacteria were subjected to matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS), 16S rDNA sequencing, and antimicrobial susceptibility testing by broth microdilution. Gram-staining and colony morphology suggested the presence of an actinomycete which was identified as N. veterana by MALDI-TOF MS. This identification was confirmed by 16S rDNA sequence analysis. Distemper-associated immunosuppression may have played a role in the pathogenesis of systemic nocardiosis in this dog. Retrospective analysis of the antimicrobial susceptibility status showed that the N. veterana isolate was multiresistant and displayed high minimal inhibitory concentrations to all antimicrobial agents used for the dog's therapy. To the best of our knowledge, this is the first report of a systemic nocardiosis caused by N. veterana in a dog with a concurrent canine distemper virus infection. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Multiresistant Bacteria Isolated from Chicken Meat in Austria

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    Gernot Zarfel

    2014-12-01

    Full Text Available Multidrug resistant bacteria (MDR bacteria, such as extended spectrum beta-lactamase (ESBL Enterobacteriaceae, methicillin resistant Staphylococcus aureus (MRSA, and vancomycin-resistant Enterococci (VRE, pose a challenge to the human health care system. In recent years, these MDR bacteria have been detected increasingly outside the hospital environment. Also the contamination of food with MDR bacteria, particularly of meat and meat products, is a concern. The aim of the study was to evaluate the occurrence of MDR bacteria in chicken meat on the Austrian market. For this study, 50 chicken meat samples were analysed. All samples originated from chickens slaughtered in Austrian slaughterhouses and were marked as produced in Austria. Samples were analysed for the presence of ESBL Enterobacteriaceae, methicillin resistant Staphylococci and VRE. Resistance genes of the isolated bacteria were characterised by PCR and sequencing. In the present study 26 ESBL producing E. coli, five mecA gene harbouring Staphylococci (but no MRSA, and four VRE were detected in chicken meat samples of Austrian origin. In 24 (48% of the samples no ESBL Enterobacteriaceae, MRSA, methicillin resistant coagulase negative Staphylococcus (MRCNS or VRE could be detected. None of the samples contained all three types of investigated multiresistant bacteria. In concordance to previous studies, CTX-M-1 and SHV-12 were the dominant ESBL genes.

  19. Photodynamic therapy for multi-resistant cutaneous Langerhans cell histiocytosis

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    Arjen F. Nikkels

    2010-06-01

    Full Text Available Langerhans cell histiocytosis is a rare group of proliferative disorders. Beside cutaneous involvement, other internal organs can be affected. The treatment of cutaneous lesions is difficult and relies on topical corticosteroids, carmustine, nitrogen mustard, and photochemotherapy. Systemic steroids and vinblastine are used for recalcitrant skin lesions. However, some cases fail to respond. An 18-month old boy presented a CD1a+, S100a+ Langerhans cell histocytosis with cutaneous and severe scalp involvement. Topical corticosteroids and nitrogen mustard failed to improve the skin lesions. Systemic corticosteroids and vinblastine improved the truncal involvement but had no effect on the scalp lesions. Methyl-aminolevulinate (MAL based photodynamic therapy (PDT resulted in a significant regression of the scalp lesions. Control histology revealed an almost complete clearance of the tumor infiltrate. Clinical follow-up after six months showed no recurrence. Although spontaneous regression of cutaneous Langerhans cell histiocytosis is observed, the rapid effect of photodynamic therapy after several failures of other treatment suggests that photodynamic therapy was successful. As far as we know this is the first report of photodynamic therapy for refractory skin lesions. Larger series are needed to determine whether photodynamic therapy deserves a place in the treatment of multiresistant cutaneous Langerhans cell histiocytosis.

  20. Nosocomial imipenem-resistant Acinetobacter baumannii infections ...

    African Journals Online (AJOL)

    Hospital stay before ICU admission, longer ICU stay, exposure to emergent surgery, the presence of central venous catheter and previous carbapenem use were significant risk factors for IRAB infection. Rationale use of carbapenems in ICUs should be considered. Keywords: Imipenem-resistant, Acinetobacter baumannii, ...

  1. Antimicrobial resistance and clonality in Acinetobacter baumannii

    NARCIS (Netherlands)

    Nemec, Alexandr

    2009-01-01

    The aim of this thesis was to obtain insight into the epidemiology and molecular basis of multidrug resistance of Acinetobacter baumannii at the population level. To this aim a number of studies were performed on strains mainly from the Czech Republic (CR) which have shown in particular that (i) the

  2. Unique Structural Modifications Are Present in the Lipopolysaccharide from Colistin-Resistant Strains of Acinetobacter baumannii

    Science.gov (United States)

    2013-10-01

    SECURITY CLASSIFICATION OF: Acinetobacter baumannii is a nosocomial opportunistic pathogen that can cause severe infections, including hospital-acquired...distribution is unlimited. Unique Structural Modifications Are Present in the Lipopolysaccharide from Colistin-Resistant Strains of Acinetobacter baumannii ...from Colistin-Resistant Strains of Acinetobacter baumannii Report Title Acinetobacter baumannii is a nosocomial opportunistic pathogen that can cause

  3. Characterization of Acinetobacter baumannii biofilm associated components

    Science.gov (United States)

    Brossard, Kari A.

    Acinetobacter baumannii is a Gram-negative aerobic coccobaccillus that is a major cause of nosocomial infections worldwide. Infected individuals may develop pneumonia, urinary tract, wound, and other infections that are associated with the use of indwelling medical devices such as catheters and mechanical ventilation. Treatment is difficult because many A. baumannii isolates have developed multi-drug resistance and the bacterium can persist on abiotic surfaces. Persistence and resistance may be due to formation of biofilms, which leads to long-term colonization, evasion of the host immune system and resistance to treatment with antibiotics and disinfectants. While biofilms are complex multifaceted structures, two bacterial components that have been shown to be important in formation and stability are exopolysaccharides (EPS) and the biofilm-associated protein (Bap). An EPS, poly-beta-1,6-N-acetylglucosamine, PNAG, has been described for E. coli and S. epidermidis. PNAG acts as an intercellular adhesin. Production of this adhesin is dependent on the pga/icaABCD locus. We have identified a homologous locus in A. baumannii 307-0294 that is involved in production of an exopolysaccharide, recognized by an anti-PNAG antibody. We hypothesized that the A. baumannii pgaABCD locus plays a role in biofilm formation, and protection against host innate defenses and disinfectants suggesting that PNAG is a possible virulence factor for the organism. The first aim of this thesis will define the pgaABCD locus. We have previously identified Bap, a protein with similarity to those described for S. aureus and we have demonstrated that this protein is involved in maintaining the stability of biofilms on glass. We hypothesized that A. baumannii Bap plays a role in persistence and pathogenesis and is regulated by quorum sensing. In our second aim we will examine the role of Bap in attachment and biofilm formation on medically relevant surfaces and also determine if Bap is involved in

  4. Country-to-country transfer of patients and the risk of multi-resistant bacterial infection.

    Science.gov (United States)

    Rogers, Benjamin A; Aminzadeh, Zohreh; Hayashi, Yoshiro; Paterson, David L

    2011-07-01

    Management of patients with a history of healthcare contact in multiple countries is now a reality for many clinicians. Leisure tourism, the burgeoning industry of medical tourism, military conflict, natural disasters, and changing patterns of human migration may all contribute to this emerging epidemiological trend. Such individuals may be both vectors and victims of healthcare-associated infection with multiresistant bacteria. Current literature describes intercountry transfer of multiresistant Acinetobacter spp and Klebsiella pneumoniae (including Klebsiella pneumoniae carbapenemase- and New Delhi metallo-β-lactamase-producing strains), methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and hypervirulent Clostridium difficile. Introduction of such organisms to new locations has led to their dissemination within hospitals. Healthcare institutions should have sound infection prevention strategies to mitigate the risk of dissemination of multiresistant organisms from patients who have been admitted to hospitals in other countries. Clinicians may also need to individualize empiric prescribing patterns to reflect the risk of multiresistant organisms in these patients. © The Author 2011. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved.

  5. High dietary zinc feeding promotes persistence of multi-resistant E. coli in the swine gut.

    Science.gov (United States)

    Ciesinski, Lisa; Guenther, Sebastian; Pieper, Robert; Kalisch, Martin; Bednorz, Carmen; Wieler, Lothar H

    2018-01-01

    High levels of zinc oxide are used frequently as feed additive in pigs to improve gut health and growth performance and are still suggested as an alternative to antimicrobial growth promoters. However, we have recently described an increase of multi-resistant E. coli in association to zinc feeding in piglets. This previous study focused on clonal diversity of E. coli, observing the effect on multi-resistant strains by chance. To shed further light into this highly important topic and falsify our previous findings, we performed a zinc pig feeding trial where we specifically focused on in-depth analysis of antimicrobial resistant E. coli. Under controlled experimental conditions, piglets were randomly allocated to a high dietary zinc (zinc group) and a background zinc feeding group (control group). At different ages samples were taken from feces, digesta, and mucosa and absolute E. coli numbers were determined. A total of 2665 E. coli isolates were than phenotypically tested for antimicrobial resistance and results were confirmed by minimum inhibitory concentration testing for random samples. In piglets fed with high dietary zinc, we detected a substantial increase of multi-resistant E. coli in all gut habitats tested, ranging from 28.9-30.2% multi-resistant E. coli compared to 5.8-14.0% in the control group. This increase was independent of the total number of E. coli. Interestingly, the total amount of the E. coli population decreased over time. Thus, the increase of the multi-resistant E. coli populations seems to be linked with persistence of the resistant population, caused by the influence of high dietary zinc feeding. In conclusion, these findings corroborate our previous report linking high dietary zinc feeding of piglets with the occurrence of antimicrobial resistant E. coli and therefore question the feeding of high dietary zinc oxide as alternative to antimicrobial growth promoters.

  6. Molecular characterization of Acinetobacter baumannii isolated from Iraqi hospital environment

    Directory of Open Access Journals (Sweden)

    I.M.S. AL-Kadmy

    2018-01-01

    Full Text Available Healthcare-associated items are a common source of acquired infections, and hospital-acquired infections cause significant mortality and morbidity worldwide. Acinetobacter baumannii is the most prevalent infection-causing organism in the hospital environment. Hospital articles and objects are the main sources of infection with the ability to transmit some of the pathogenic microorganisms such as A. baumannii, which is considered a serious problem in therapeutic treatments. In the current study, we isolated A. baumannii from hospital sources and evaluated its antibiotic resistance, virulence factors and resistance gene determinants. The isolates were identified phenotypically as well as genotypically using PCR. In addition, their capability for biofilm formation and ten other virulence factors were measured. Of 112 samples, 21 showed growth of the target organism. Apart from A. baumannii, isolates of Candida albicans, Staphylococcus sp., Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae were also grown. Antibiotic susceptibility test results considered all the A. baumannii to be multidrug-resistant isolates with the highest resistance being 100% to gentamycin, ciprofloxacin; the most effective antibiotics with 100% susceptibility was colistin and tigecycline. All A. baumannii isolates had MIC for ceftriaxone >32 mg/L. All A. baumannii isolates from the hospital environment showed multidrug resistance and had many virulence factors. They have long-term resistance to dry conditions and cause a serious public health issue.

  7. Acinetobacter baumannii: Evolution of Antimicrobial Resistance—Treatment Options

    Science.gov (United States)

    Doi, Yohei; Murray, Gerald L.; Peleg, Anton Y.

    2015-01-01

    The first decade of the 20th century witnessed a surge in the incidence of infections due to several highly antimicrobial-resistant bacteria in hospitals worldwide. Acinetobacter baumannii is one such organism that turned from an occasional respiratory pathogen into a major nosocomial pathogen. An increasing number of A. baumannii genome sequences have broadened our understanding of the genetic makeup of these bacteria and highlighted the extent of horizontal transfer of DNA. Animal models of disease combined with bacterial mutagenesis have provided some valuable insights into mechanisms of A. baumannii pathogenesis. Bacterial factors known to be important for disease include outer membrane porins, surface structures including capsule and lipopolysaccharide, enzymes such as phospholipase D, iron acquisition systems, and regulatory proteins. A. baumannii has a propensity to accumulate resistance to various groups of antimicrobial agents. In particular, carbapenem resistance has become commonplace, accounting for the majority of A. baumannii strains in many hospitals today. Carbapenem-resistant strains are often resistant to all other routinely tested agents. Treatment of carbapenem-resistant A. baumannii infection therefore involves the use of combinations of last resort agents such as colistin and tigecycline, but the efficacy and safety of these approaches are yet to be defined. Antimicrobial-resistant A. baumannii has high potential to spread among ill patients in intensive care units. Early recognition and timely implementation of appropriate infection control measures is crucial in preventing outbreaks. PMID:25643273

  8. Drug resistance patterns of acinetobacter baumannii in makkah, saudi arabia

    International Nuclear Information System (INIS)

    Khan, M.A.; Ashshi, A.M.; Mahomed, M.F.

    2012-01-01

    Background: Acinetobacter baumannii causes infections of respiratory, urinary tract, blood stream and surgical sites. Its clinical significance has increased due to its rapidly developing resistance to major groups of antibiotics used for its treatment. There is limited data available on antimicrobial susceptibility of A. baumannii from Saudi Arabia. Objectives: To determine the patterns of drug resistance of Acinetobacter baumannii and predisposing factors for its acquisition.Subjects and Methods: In this descriptive study, 72 hospitalized patients infected with A baumannii were studied. The clinical and demographic data of the patients were collected using a predesigned questionnaire. Isolation and identification of A.baumannii from all clinical specimens were done using standard microbiological methods. Antibiotic susce ptibility testing was performed by disk diffusion method recommended by Clinical Laboratory Standards Institute. Results: Majority of the isolates (61.1%) were from respiratory tract infections. A.baumannii isolates showed high drug resistance to piperacil lin (93.1%), aztreonam (80.5%), ticarcillin, ampicillin, and tetracycline (76.4%, each) and cefotaxime (75%). Only amikacin showed low rate of resistance compared to other antibiotics (40.3%). About 36% patients had some underlying diseases with diabetes mellitus (11%) being the predominant underlying disease. Conclusions: High antimicrobial resistance to commonly used antibiotics was seen against A.baumannii isolates. Only amikacin was most effective against it. (author)

  9. Acinetobacter baumannii Infection in Transfusion Dependent Thalassemia Patients with Sepsis

    Directory of Open Access Journals (Sweden)

    Muzaheed Abdul Rasheed

    2017-01-01

    Full Text Available Purpose. To identify the Acinetobacter baumannii infection among transfusion dependent thalassemia patients. Methods. A quantitative approach was employed to assess Acinetobacter baumannii infection in transfusion dependent thalassemia patients. Samples were collected from 916 patients, which have shown bacterial growth on MacConkey and blood agar culture media. A. baumannii strains were identified by microbiological methods and Gram’s staining. API 20 E kit (Biomerieux, USA was used for final identification. Results. From 916 cultured blood specimens, 107 (11.6% showed growth of A. baumannii. Serum ferritin in thalassemic patients without bacterial infections was 3849.5±1513.5 µg/L versus 6413.5±2103.9 µg/L in those with bacterial infections (p=0.0001. Acinetobacter baumannii infected patients have shown higher serum ferritin levels (p=0.0001. Serum ferritin in thalassemic patients was 3849.5±1513.5 µg/L versus 6413.5±2103.9 µg/L in those with bacterial infections (p=0.0001. Acinetobacter baumannii infected patients showed high serum ferritin levels (p=0.0001. The clinical symptoms have been found with A. baumannii +ve with a mean and standard deviation of 47 (5.1% and A. baumannii −ve with mean and standard deviation of 60 (6.5%. Conclusion. Isolation of asymptomatic A. baumannii from the thalassemia patients shows an alarming situation of bacterial infections. A continuous surveillance of transfusion dependent thalassemia patients is recommended for bacterial sepsis.

  10. [Infections caused by multi-resistant Gram-positive bacteria (Staphylococcus aureus and Enterococcus spp.)].

    Science.gov (United States)

    Cantón, Rafael; Ruiz-Garbajosa, Patricia

    2013-10-01

    Methicillin -resistant Staphylocccus aureus (MRSA) and multirresistant entorococci are still problematic in nosocomial infections and new challenges have emerged for their containment. MRSA has increased the multiresistant profile; it has been described vancomycin and linezolid resistant isolates and isolates with decreased daptomycin susceptibility. Moreover, new clones (ST398) have emerged, initially associated with piggeries, and new mec variants (mecC) with livestock origin that escape to the detection with current molecular methods based on mecA gene have been detected. In enterococci, linzeolid resistant isolates and isolates with deceased susceptibility to daptomycin have been described. Moreover, ampicillin resistant Enterococcus faecium due to β-lactamase production has been recently found in Europe. Control of MRSA isolates and multiresistant enteroccocci should combined antibiotic stewardship strategies and epidemiological measures, including detection of colonized patients in order to reduce colonization pressure and their transmission. Copyright © 2013 Elsevier España, S.L. All rights reserved.

  11. Expanding subjectivities

    DEFF Research Database (Denmark)

    Lundgaard Andersen, Linda; Soldz, Stephen

    2012-01-01

    A major theme in recent psychoanalytic thinking concerns the use of therapist subjectivity, especially “countertransference,” in understanding patients. This thinking converges with and expands developments in qualitative research regarding the use of researcher subjectivity as a tool...... to understanding, especially but not exclusively in observational and interview-based studies. Psychodynamic or psychoanalytic approaches to research add an emphasis on unconscious motivational processes in both researchers and research participants that impact research experience and data. Building upon Anglo......-Saxon and continental traditions, this special issue provides examples of the use of researcher subjectivity, informed by psychoanalytic thinking, in expanding research understanding....

  12. Colistin: an antibiotic and its role in multiresistant Gram-negative infections.

    Science.gov (United States)

    Loho, Tonny; Dharmayanti, Anti

    2015-04-01

    Increasing number of infection cases caused by multiresistant Gram-negative bacteria or multidrug resistant organism (MDRO) has become a major problem worldwide since there have been a lot of resistance to many classes of antibiotics. Mutant isolates such as fluoroquinolone-resistant and -lactamase-resistant bacteria have been commonly found, particularly in intensive care unit (ICU). During the last two decades, there has been no study of developing antibiotics in search of discovering new type of antibiotics; meanwhile, the resistance of Gram-negative bacteria or MDRO to antibiotics is increasing. Colistin or polymyxin E is an old antibiotic, which has been used since 1959 for treating infection caused by Gram-negative MDRO. It was revealed that colistin has side effects of nephrotoxicity and neurotoxicity; therefore, the use of this antibiotic was stopped and it was replaced by other antibiotics which were effective and were considered safer at that time. There is an increasing number of infections with multi-resistant Gram-negative (MDRO) against the available antibiotics and the availability of alternative antibiotics has not been satisfying; therefore, microbiologists are searching back to the old option, which has been proven to be effective against multi-resistant Gram-negative bacteria, the old antibiotic that has been long forgotten, i.e. colistin, as an alternative treatment against Gram-negative MDRO. It is expected that colistin may have essential and reliable role as future antibiotics for treatment of multi-resistant Gram-negative infections and as an alternative of antibiotics that have been available so far.

  13. Colistin: an Antibiotic and Its Role in Multiresistant Gram-negative Infections

    Directory of Open Access Journals (Sweden)

    Tonny Loho

    2016-05-01

    Full Text Available Increasing number of infection cases caused by multiresistant Gram-negative bacteria or multidrug resistant organism (MDRO has become a major problem worldwide since there have been a lot of resistance to many classes of antibiotics. Mutant isolates such as fluoroquinolone-resistant and β-lactamase-resistant bacteria have been commonly found, particularly in intensive care unit (ICU. During the last two decades, there has been no study of developing antibiotics in search of discovering new type of antibiotics; meanwhile, the resistance of Gram-negative bacteria or MDRO to antibiotics is increasing. Colistin or polymyxin E is an old antibiotic, which has been used since 1959 for treating infection caused by Gram-negative MDRO. It was revealed that colistin has side effects of nephrotoxicity and neurotoxicity; therefore, the use of this antibiotic was stopped and it was replaced by other antibiotics which were effective and were considered safer at that time. There is an increasing number of infections with multi-resistant Gram-negative (MDRO against the available antibiotics and the availability of alternative antibiotics has not been satisfying; therefore, microbiologists are searching back to the old option, which has been proven to be effective against multi-resistant Gram-negative bacteria, the old antibiotic that has been long forgotten, i.e. colistin, as an alternative treatment against Gram-negative MDRO. It is expected that colistin may have essential and reliable role as future antibiotics for treatment of multi-resistant Gram-negative infections and as an alternative of antibiotics that have been available so far. Key words: antibiotics, colistin, Gram-negative, multidrug resistant organism (MDRO.

  14. A case report of long term bevacizumab treatment in multiresistant ovarian cancer

    DEFF Research Database (Denmark)

    Kargo, Anette Stolberg; Adimi, Parvin; Dahl-Steffensen, Karina

    2016-01-01

    Treatment of multiresistant ovarian cancer is palliative and patients have needs for less toxic treatment. Anti-angiogenic treatments have a less toxic profile, and bevacizumab has shown improvement of progression free survival (PFS) in front-line trials. Bevacizumab is generally introduced in co...... in combination with chemotherapy; however this case report will describe the use of single-agent bevacizumab for more than five years (102 cycles) in a patient with relapse of advanced ovarian cancer...

  15. Antimicrobial Potential of Momordica charantia L. against Multiresistant Standard Species and Clinical Isolates.

    Science.gov (United States)

    Lucena Filho, José Hardman Sátiro de; Lima, Rennaly de Freitas; Medeiros, Ana Claudia Dantas de; Pereira, Jozinete Vieira; Granville-Garcia, Ana Flávia; Costa, Edja Maria Melo de Brito

    2015-11-01

    The aim of the present study was to evaluate the antibacterial and antifungal potential in vitro of Momordica charantia L. against the microorganisms of clinical interest (standard strains and multiresistant isolates) in order to aggregate scientific information in relation to its use as a therapeutic product. M. charantia L. plant material was acquired in municipality of Malta, Paraiba, Brazil. The extract was obtained through maceration, filtration and then concentrated under reduced pressure in a rotary evaporator, resulting in a dough, and was then dried in an oven for 72 hours at 40°C. Antimicrobial action of ethanolic extract of seed M. charantia L. was evaluated based on the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) against standard strains of bacteria, isolates multiresistant bacteria and Candida species, by microdilution in broth method. All organisms were sensitive to the extract, being considered strong antimicrobial activity (MIC and MBC/MFC charantia L. showed strong antimicrobial potential, with bactericidal and fungicidal profile, there is the prospect to constitute a new therapeutic strategy for the control of infections, particularly in multiresistant strains. The use of medicinal plants in treatment of infectious processes have an important function nowadays, due to the limitations of the use of synthetic antibiotics available, related specifically to the microbial resistance emergence.

  16. Degenerate primer MOB typing of multiresistant clinical isolates of E. coli uncovers new plasmid backbones.

    Science.gov (United States)

    Garcillán-Barcia, M Pilar; Ruiz del Castillo, Belén; Alvarado, Andrés; de la Cruz, Fernando; Martínez-Martínez, Luis

    2015-01-01

    Degenerate Primer MOB Typing is a PCR-based protocol for the classification of γ-proteobacterial transmissible plasmids in five phylogenetic relaxase MOB families. It was applied to a multiresistant E. coli collection, previously characterized by PCR-based replicon-typing, in order to compare both methods. Plasmids from 32 clinical isolates of multiresistant E. coli (19 extended spectrum beta-lactamase producers and 13 non producers) and their transconjugants were analyzed. A total of 95 relaxases were detected, at least one per isolate, underscoring the high potential of these strains for antibiotic-resistance transmission. MOBP12 and MOBF12 plasmids were the most abundant. Most MOB subfamilies detected were present in both subsets of the collection, indicating a shared mobilome among multiresistant E. coli. The plasmid profile obtained by both methods was compared, which provided useful data upon which decisions related to the implementation of detection methods in the clinic could be based. The phylogenetic depth at which replicon and MOB-typing classify plasmids is different. While replicon-typing aims at plasmid replication regions with non-degenerate primers, MOB-typing classifies plasmids into relaxase subfamilies using degenerate primers. As a result, MOB-typing provides a deeper phylogenetic depth than replicon-typing and new plasmid groups are uncovered. Significantly, MOB typing identified 17 plasmids and an integrative and conjugative element, which were not detected by replicon-typing. Four of these backbones were different from previously reported elements. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. [Incidence of multi-resistant bacteria in Intensive Care Units of Chilean hospitals].

    Science.gov (United States)

    Acuña, M Paz; Cifuentes, Marcela; Silva, Francisco; Rojas, Álvaro; Cerda, Jaime; Labarca, Jaime

    2017-12-01

    Incidence of multi-resistant bacteria is an indicator that permits better estimation of the magnitude of bacterial resistance in hospitals. To evaluate the incidence of relevant multi-drug resistant bacteria in intensive care units (ICUs) of Chile. Participating hospitals submitted information about the number of isolates from infected or colonized patients with 7 epidemiologically relevant multi-resistant bacteria in adult and pediatric ICUs between January 1, 2014 and October 31, 2015 and the number of bed days occupied in these units in the same period was requested. With these data incidence was calculated per 1,000 patient days for each unit. Information from 20 adults and 9 pediatric ICUs was reviewed. In adult ICUs the bacteria with the highest incidence were K. pneumoniae ESBL [4.72 × 1,000 patient day (1.21-13.89)] and oxacillin -resistant S. aureus [3.85 (0.71-12.66)]. In the pediatric units the incidence was lower, highlighting K. pneumoniae ESBL [2.71 (0-7.11)] and carbapenem -resistant P. aeruginosa [1.61 (0.31-9.25)]. Important differences between hospitals in the incidence of these bacteria were observed. Incidence of multi-resistant bacteria in adult ICU was significantly higher than in pediatric ICU for most of the studied bacterias.

  18. Expander Codes

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 1. Expander Codes - The Sipser–Spielman Construction. Priti Shankar. General Article Volume 10 ... Author Affiliations. Priti Shankar1. Department of Computer Science and Automation, Indian Institute of Science Bangalore 560 012, India.

  19. Interplay between Colistin Resistance, Virulence and Fitness in Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Gabriela Jorge Da Silva

    2017-11-01

    Full Text Available Acinetobacter baumannii is an important opportunistic nosocomial pathogen often resistant to multiple antibiotics classes. Colistin, an “old” antibiotic, is now considered a last-line treatment option for extremely resistant isolates. In the meantime, resistance to colistin has been reported in clinical A. baumannii strains. Colistin is a cationic peptide that disrupts the outer membrane (OM of Gram-negative bacteria. Colistin resistance is primarily due to post-translational modification or loss of the lipopolysaccharide (LPS molecules inserted into the outer leaflet of the OM. LPS modification prevents the binding of polymyxin to the bacterial surface and may lead to alterations in bacterial virulence. Antimicrobial pressure drives the evolution of antimicrobial resistance and resistance is often associated with a reduced bacterial fitness. Therefore, the alterations in LPS may induce changes in the fitness of A. baumannii. However, compensatory mutations in clinical A. baumannii may ameliorate the cost of resistance and may play an important role in the dissemination of colistin-resistant A. baumannii isolates. The focus of this review is to summarize the colistin resistance mechanisms, and understand their impact on the fitness and virulence of bacteria and on the dissemination of colistin-resistant A. baumannii strains.

  20. Endemic Acinetobacter baumannii in a New York hospital.

    Directory of Open Access Journals (Sweden)

    Scott A Weisenberg

    Full Text Available Acinetobacter baumannii is an increasingly multidrug-resistant (MDR cause of hospital-acquired infections, often associated with limited therapeutic options. We investigated A. baumannii isolates at a New York hospital to characterize genetic relatedness.Thirty A. baumannii isolates from geographically-dispersed nursing units within the hospital were studied. Isolate relatedness was assessed by repetitive sequence polymerase chain reaction (rep-PCR. The presence and characteristics of integrons were assessed by PCR. Metabolomic profiles of a subset of a prevalent strain isolates and sporadic isolates were characterized and compared.We detected a hospital-wide group of closely related carbapenem resistant MDR A. baumannii isolates. Compared with sporadic isolates, the prevalent strain isolates were more likely to be MDR (p = 0.001. Isolates from the prevalent strain carried a novel Class I integron sequence. Metabolomic profiles of selected prevalent strain isolates and sporadic isolates were similar.The A. baumannii population at our hospital represents a prevalent strain of related MDR isolates that contain a novel integron cassette. Prevalent strain and sporadic isolates did not segregate by metabolomic profiles. Further study of environmental, host, and bacterial factors associated with the persistence of prevalent endemic A. baumannii strains is needed to develop effective prevention strategies.

  1. Emergence of New Delhi metallo-beta-lactamase 1 and other carbapenemase-producing Acinetobacter calcoaceticus-baumannii complex among patients in hospitals in Ha Noi, Viet Nam.

    Science.gov (United States)

    Tran, D N; Tran, H H; Matsui, M; Suzuki, M; Suzuki, S; Shibayama, K; Pham, T D; Van Phuong, T T; Dang, D A; Trinh, H S; Loan, C T; Nga, L T V; van Doorn, H R; Wertheim, H F L

    2017-02-01

    Acinetobacter baumannii is an important cause of multidrug-resistant hospital acquired infections in the world. Here, we investigate the presence of NDM-1 and other carbapenemases among carbapenem-resistant A. baumannii isolated between August 2010 and December 2014 from three large hospitals in Hanoi, Vietnam. We identified 23/582 isolates (4 %) (11 from hospital A, five from hospital B, and seven from hospital C) that were NDM-1 positive, and among them 18 carried additional carbapenemase genes, including seven isolates carrying NDM-1, IMP-1, and OXA-58 with high MICs for carbapenems. Genotyping indicated that NDM-1 carrying A. baumannii have expanded clonally in these hospitals. Five new STs (ST1135, ST1136, ST1137, ST1138, and ST1139) were identified. One isolate carried NDM-1 on a plasmid belonging to the N-repA replicon type; no NDM-1-positive plasmids were identified in the other isolates. We have shown the extent of the carbapenem resistance and the local clonal spread of A. baumannii carrying NDM-1 in these hospitals; coexistence of NDM-1 and IMP-1 is reported for the first time from Vietnam here, and this will further seriously limit future therapeutic options.

  2. Partition expanders

    Czech Academy of Sciences Publication Activity Database

    Gavinsky, Dmitry; Pudlák, Pavel

    2017-01-01

    Roč. 60, č. 3 (2017), s. 378-395 ISSN 1432-4350 R&D Projects: GA ČR GBP202/12/G061 Institutional support: RVO:67985840 Keywords : expanders * pseudo randomness * communication complexity Subject RIV: BA - General Mathematics OBOR OECD: Computer sciences, information science, bioinformathics (hardware development to be 2.2, social aspect to be 5.8) Impact factor: 0.645, year: 2016 http://link.springer.com/article/10.1007%2Fs00224-016-9738-5

  3. Partition expanders

    Czech Academy of Sciences Publication Activity Database

    Gavinsky, Dmitry; Pudlák, Pavel

    2017-01-01

    Roč. 60, č. 3 (2017), s. 378-395 ISSN 1432-4350 R&D Projects: GA ČR GBP202/12/G061 Institutional support: RVO:67985840 Keywords : expanders * pseudorandomness * communication complexity Subject RIV: BA - General Mathematics OBOR OECD: Computer sciences, information science, bioinformathics (hardware development to be 2.2, social aspect to be 5.8) Impact factor: 0.645, year: 2016 http://link.springer.com/article/10.1007%2Fs00224-016-9738-5

  4. A novel bacterial transport mechanism of Acinetobacter baumannii via activated human neutrophils through interleukin-8.

    Science.gov (United States)

    Kamoshida, Go; Tansho-Nagakawa, Shigeru; Kikuchi-Ueda, Takane; Nakano, Ryuichi; Hikosaka, Kenji; Nishida, Satoshi; Ubagai, Tsuneyuki; Higashi, Shouichi; Ono, Yasuo

    2016-12-01

    Hospital-acquired infections as a result of Acinetobacter baumannii have become problematic because of high rates of drug resistance. Although neutrophils play a critical role in early protection against bacterial infection, their interactions with A. baumannii remain largely unknown. To elucidate the interactions between A. baumannii and human neutrophils, we cocultured these cells and analyzed them by microscopy and flow cytometry. We found that A. baumannii adhered to neutrophils. We next examined neutrophil and A. baumannii infiltration into Matrigel basement membranes by an in vitro transmigration assay. Neutrophils were activated by A. baumannii, and invasion was enhanced. More interestingly, A. baumannii was transported together by infiltrating neutrophils. Furthermore, we observed by live cell imaging that A. baumannii and neutrophils moved together. In addition, A. baumannii-activated neutrophils showed increased IL-8 production. The transport of A. baumannii was suppressed by inhibiting neutrophil infiltration by blocking the effect of IL-8. A. baumannii appears to use neutrophils for transport by activating these cells via IL-8. In this study, we revealed a novel bacterial transport mechanism that A. baumannii exploits human neutrophils by adhering to and inducing IL-8 release for bacterial portage. This mechanism might be a new treatment target. © Society for Leukocyte Biology.

  5. Protein, Lipid, Chemical and Structural Signatures of Differentially-Cultivated Francisella tularensis and Acinetobactor baumannii

    Science.gov (United States)

    2014-03-05

    Resistant Strains of Acinetobacter baumannii , Antimicrobial Agents and Chemotherapy, (07 2013): 0. doi: 10.1128/AAC.00865-13 Bibiana V Iglesias...Q. Shanks, Y. Doi. Activities of Vancomycin-Containing Regimens against Colistin-Resistant Acinetobacter baumannii Clinical Strains, Antimicrobial... Acinetobacter baumannii , Antimicrobial Agents and Chemotherapy (04 2013) TOTAL: 1 Received Paper TOTAL: PERCENT_SUPPORTEDNAME FTE Equivalent: Total

  6. Spondylodiscitis by drug-multiresistant bacteria: a single-center experience of 25 cases.

    Science.gov (United States)

    Shiban, Ehab; Janssen, Insa; Wostrack, Maria; Krieg, Sandro M; Horanin, Monika; Stoffel, Michael; Meyer, Bernhard; Ringel, Florian

    2014-12-01

    Although the incidence of pyogenic spinal infections is increasing, the ideal treatment of spondylodiscitis is still a controversially discussed issue. Furthermore, the proportion of multiresistant bacteria in spondylodiscitis is increasing, and treatment recommendations or reported results are missing for this especially difficult subset of patients. The aim of this study is to evaluate the surgical outcome and the postoperative antibacterial treatment regime. Retrospective case series. Patients treated for a spondylodiscitis from multiresistant bacteria at our department between 2006 and 2011. Data were gathered through review of patients' case notes, relevant imaging, and electronic records. Magnetic resonance imaging of the whole spine including gadolinium (Gd)-enhanced T1 sequences and computed tomography scans of the affected regions were obtained in all cases. C-reactive protein (CRP) and complete blood cell count were analyzed in all cases using routine laboratory techniques. Neurologic deficits were classified according to the American Spinal Injury Association (ASIA) impairment scale. Twenty-five patients were identified (15 gram-positive and 10 gram-negative drug-multiresistant bacteria). The mean age at presentation was 66 years, and 14 patients were male (56%). All patients presented with pain, and a neurologic deficit was present in 11 (44%) cases. An epidural abscess was found in 11 (44%) cases. At admission, CRP was elevated in all cases with a mean of 13±9.2 mg/dL. The main source of infection was previous spine surgery (36%). All patients in this series underwent surgical debridement of the infection and instrumentation of the spine. Postoperative intravenous antibiotics were administered for 19±8.6 days followed by 3±0.3 months of oral antibiotic therapy. Eradication of the infection was achieved ultimately in all surviving patients. Out of 11 patients with neurologic deficits, 4 had a full recovery, 4 improved incompletely, and 3 remained

  7. Zinc stress induces copper depletion in Acinetobacter baumannii.

    Science.gov (United States)

    Hassan, Karl A; Pederick, Victoria G; Elbourne, Liam D H; Paulsen, Ian T; Paton, James C; McDevitt, Christopher A; Eijkelkamp, Bart A

    2017-03-11

    The first row transition metal ions zinc and copper are essential to the survival of many organisms, although in excess these ions are associated with significant toxicity. Here, we examined the impact of zinc and copper stress on Acinetobacter baumannii, a common opportunistic pathogen. We show that extracellular zinc stress induces a copper-specific depletion phenotype in A. baumannii ATCC 17978. Supplementation with copper not only fails to rescue this phenotype, but further exacerbates the copper depletion. Extensive analysis of the A. baumannii ATCC 17978 genome identified 13 putative zinc/copper resistance efflux pumps. Transcriptional analyses show that four of these transporters are responsive to zinc stress, five to copper stress and seven to the combination of zinc and copper stress, thereby revealing a likely foundation for the zinc-induced copper starvation in A. baumannii. In addition, we show that zinc and copper play crucial roles in management of oxidative stress and the membrane composition of A. baumannii. Further, we reveal that zinc and copper play distinct roles in macrophage-mediated killing of this pathogen. Collectively, this study supports the targeting of metal ion homeostatic mechanisms as an effective antimicrobial strategy against multi-drug resistant bacterial pathogens.

  8. Increased levels of multiresistant bacteria and resistance genes after wastewater treatment and their dissemination into Lake Geneva, Switzerland

    Directory of Open Access Journals (Sweden)

    Nadine eCzekalski

    2012-03-01

    Full Text Available At present, very little is known about the fate and perseverance of multiresistant bacteria and their resistance genes in natural aquatic environments. Treated, but partly also untreated sewage of the city of Lausanne, Switzerland is discharged into Vidy bay (Lake Geneva resulting in high levels of contamination in this part of the lake. In the present work we have studied the prevalence of multiresistant bacteria and resistance genes in the wastewater stream of Lausanne. Samples from hospital and municipal raw sewage, treated effluent from Lausanne’s wastewater treatment plant (WTP as well as lake water and sediment samples obtained close to the WTP outlet pipe and a remote site close to a drinking water pump were evaluated for the prevalence of multiresistant bacteria. Selected isolates were identified (16S rRNA gene fragment sequencing and characterized with regards to further resistances, resistance genes, and plasmids. Mostly, studies investigating this issue have relied on cultivation-based approaches. However, the limitations of these tools are well known, in particular for environmental microbial communities, and cultivation-independent molecular tools should be applied in parallel in order to take non-culturable organisms into account. Here we directly quantified the sulfonamide resistance genes sul1 and sul2 from environmental DNA extracts using TaqMan real-time quantitative PCR. Hospital sewage contained the highest load of multiresistant bacteria and antibiotic resistance genes. Wastewater treatment reduced the total bacterial load but evidence for selection of extremely multiresistant strains and accumulation of resistance genes was observed. Our data clearly indicated pollution of sediments with antibiotic resistance genes in the vicinity of the WTP outlet. The potential of lakes as reservoirs of multiresistant bacteria and potential risks are discussed.

  9. Differences in composition of honey samples and their impact on the antimicrobial activities against drug multiresistant bacteria and pathogenic fungi.

    Science.gov (United States)

    AL-Waili, Noori; Al Ghamdi, Ahmad; Ansari, Mohammad Javed; Al-Attal, Yehya; Al-Mubarak, Aarif; Salom, Khelod

    2013-05-01

    Antibiotic multiresistant microbes represent a challenging problem. Because honey has a potent antibacterial property, the antimicrobial effects of different honey samples against multiresistant pathogens and their compositions were investigated. Five honey samples were used: Talah, Dhahian, Sumra-1, Sidr, and Sumra-2. Samples were analyzed to determine chemical composition such as fructose, glucose, sucrose, pH, total flavonoids, total phenolics, hydrogen peroxide concentration, minerals and trace elements. Antimicrobial activities of the samples against 17 (16 were multiresistant) human pathogenic bacteria and three types of fungi were studied. Specimens of the isolates were cultured into 10 mL of 10-100% (volume/volume) honey diluted in broth. Microbial growth was assessed on a solid plate media after 24 h and 72 h incubation. The composition of honey samples varied considerably. Sumra 1 and 2 contained the highest level of flavonoids and phenolics and the lowest level of hydrogen peroxide, whereas Dhahian honey contained the highest level of hydrogen peroxide. Sixteen pathogens were antibiotic multiresistant. A single dose of each honey sample inhibited all the pathogens tested after 24 h and 72 h incubation. The most sensitive pathogens were Aspergillus nidulans, Salmonella typhimurum and Staphylococcus epidermidis (S. epidermidis). Although there was no statistically significant difference in the effectiveness of honey samples, the most effective honey against bacteria was Talah and against fungi were Dhahian and Sumra-2. Various honey samples collected from different geographical areas and plant origins showed almost similar antimicrobial activities against multiresistant pathogens despite considerable variation in their composition. Honey may represent an alternative candidate to be tested as part of management of drug multiresistant pathogens. Copyright © 2013 IMSS. Published by Elsevier Inc. All rights reserved.

  10. Current molecular methods in epidemiological typing of Acinetobacter baumannii.

    Science.gov (United States)

    Rafei, Rayane; Kempf, Marie; Eveillard, Matthieu; Dabboussi, Fouad; Hamze, Monzer; Joly-Guillou, Marie-Laure

    2014-01-01

    The emergence of Acinetobacter baumannii during recent decades as an important nosocomial pathogen responsible of worldwide, intensively documented, outbreaks has resulted in a need for effective epidemiological typing methods. Throughout the years, many typing methods for A. baumannii epidemiological studies have been proposed from phenotypic to molecular methods. Currently, the use of phenotypic typing methods have declined considerably and been progressively replaced by molecular methods. In this review, we introduce the current molecular methods available for A. baumannii typing. Each method has its own advantages and disadvantages, and the selection of an appropriate genotyping method depends on studied objectives. This review sheds light on questions in different epidemiological settings and most molecular methods used to fit these objectives.

  11. Clonal relationships among penicillin-susceptible, multiresistant serotype 6B Streptococcus pneumoniae isolates recovered in Greece and France.

    Science.gov (United States)

    Syrogiannopoulos, G A; Doit, C; Grivea, I N; Geslin, P; Bingen, E

    2001-01-01

    In January 1996 the emergence of penicillin-susceptible, multiresistant serotype 6B Streptococcus pneumoniae isolates resistant to chloramphenicol, tetracycline, erythromycin, clindamycin and trimethoprim-sulfamethoxazole was observed in young carriers in the city of Patras, located in the southwestern region of Greece. Later, a significant spread of pneumococci with this unusual phenotype was noted in carriers living in various other areas of the country. Using restriction fragment length polymorphism of the ribosomal RNA genes, clonal relationships were found between these Greek strains and serotype 6B penicillin-susceptible, multiresistant pneumococci isolated in France between January 1992 and September 1996. The French and Greek isolates appear to have a common ancestry.

  12. Modeling Acinetobacter baumannii wound infections: The critical role of iron

    Science.gov (United States)

    Fleming, Irma D.; Krezalek, Monika A.; Belogortseva, Natalia; Zaborin, Alexander; Defazio, Jennifer; Chandrasekar, Laxmipradha; Actis, Luis A.; Zaborina, Olga; Alverdy, John C.

    2016-01-01

    Background Acinetobacter baumannii has emerged as an increasingly important and successful opportunistic human pathogen due to its ability to withstand harsh environmental conditions, its characteristic virulence factors and quick adaptability to stress. Methods We developed a clinically relevant murine model of A. baumannii traumatic wound infection to determine the effect of local wound environment on A. baumannii virulence. Mice underwent rectus muscle crush injury combined with ischemia created by epigastric vessel ligation, followed by A. baumannii inoculation. Reiterative experiments were performed using 1) a mutant deficient in the production of the siderophore acinetobactin, or 2) iron supplementation of the wound milieu. Mice were euthanized 7 days later and rectus muscle analyzed for signs of clinical infection, HIF1α accumulation, bacterial abundance and colony morphotype. To determine the effect of wound milieu on bacterial virulence, the Galleria mellonella infection model was utilized. Results The combination of rectus muscle injury with ischemia and A. baumannii inoculation resulted in 100% incidence of clinical wound infection that was significantly higher compared to other groups (n=15/group, pbaumannii colonization (pbaumannii strains isolated from injured/ischemic muscle with clinical infection displayed a rough morphotype and a higher degree of virulence as judged by G. mellonella killing assay as compared to smooth morphotype colonies isolated from injured muscle without clinical infection (100% vs. 60%, n=30 Log-Rank test, p=0.0422). Iron supplementation prevented wound infection (n=30, pbaumannii wild type was replaced with its derivative mutant ΔBasD deficient in acinetobactin production. Conclusions The ability of A. baumannii to cause infections in traumatized wound relies on its ability to scavenge iron and can be prevented by iron supplementation to the wound milieu. PMID:28030490

  13. Epidemiologic and Clinical Impact of Acinetobacter baumannii Colonization and Infection

    Science.gov (United States)

    Villar, Macarena; Cano, María E.; Gato, Eva; Garnacho-Montero, José; Miguel Cisneros, José; Ruíz de Alegría, Carlos; Fernández-Cuenca, Felipe; Martínez-Martínez, Luis; Vila, Jordi; Pascual, Alvaro; Tomás, María; Bou, Germán; Rodríguez-Baño, Jesús

    2014-01-01

    Abstract Acinetobacter baumannii is one of the most important antibiotic-resistant nosocomial bacteria. We investigated changes in the clinical and molecular epidemiology of A. baumannii over a 10-year period. We compared the data from 2 prospective multicenter cohort studies in Spain, one performed in 2000 (183 patients) and one in 2010 (246 patients), which included consecutive patients infected or colonized by A. baumannii. Molecular typing was performed by repetitive extragenic palindromic polymerase chain reaction (REP-PCR), pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST). The incidence density of A. baumannii colonization or infection increased significantly from 0.14 in 2000 to 0.52 in 2010 in medical services (p < 0.001). The number of non-nosocomial health care-associated cases increased from 1.2% to 14.2%, respectively (p < 0.001). Previous exposure to carbapenems increased in 2010 (16.9% in 2000 vs 27.3% in 2010, p = 0.03). The drugs most frequently used for definitive treatment of patients with infections were carbapenems in 2000 (45%) and colistin in 2010 (50.3%). There was molecular-typing evidence of an increase in the frequency of A. baumannii acquisition in non-intensive care unit wards in 2010 (7.6% in 2000 vs 19.2% in 2010, p = 0.01). By MSLT, the ST2 clonal group predominated and increased in 2010. This epidemic clonal group was more frequently resistant to imipenem and was associated with an increased risk of sepsis, although not with severe sepsis or mortality. Some significant changes were noted in the epidemiology of A. baumannii, which is increasingly affecting patients admitted to conventional wards and is also the cause of non-nosocomial health care-associated infections. Epidemic clones seem to combine antimicrobial resistance and the ability to spread, while maintaining their clinical virulence. PMID:25181313

  14. Copper Resistance of the Emerging Pathogen Acinetobacter baumannii.

    Science.gov (United States)

    Williams, Caitlin L; Neu, Heather M; Gilbreath, Jeremy J; Michel, Sarah L J; Zurawski, Daniel V; Merrell, D Scott

    2016-10-15

    Acinetobacter baumannii is an important emerging pathogen that is capable of causing many types of severe infection, especially in immunocompromised hosts. Since A. baumannii can rapidly acquire antibiotic resistance genes, many infections are on the verge of being untreatable, and novel therapies are desperately needed. To investigate the potential utility of copper-based antibacterial strategies against Acinetobacter infections, we characterized copper resistance in a panel of recent clinical A. baumannii isolates. Exposure to increasing concentrations of copper in liquid culture and on solid surfaces resulted in dose-dependent and strain-dependent effects; levels of copper resistance varied broadly across isolates, possibly resulting from identified genotypic variation among strains. Examination of the growth-phase-dependent effect of copper on A. baumannii revealed that resistance to copper increased dramatically in stationary phase. Moreover, A. baumannii biofilms were more resistant to copper than planktonic cells but were still susceptible to copper toxicity. Exposure of bacteria to subinhibitory concentrations of copper allowed them to better adapt to and grow in high concentrations of copper; this copper tolerance response is likely achieved via increased expression of copper resistance mechanisms. Indeed, genomic analysis revealed numerous putative copper resistance proteins that share amino acid homology to known proteins in Escherichia coli and Pseudomonas aeruginosa Transcriptional analysis revealed significant upregulation of these putative copper resistance genes following brief copper exposure. Future characterization of copper resistance mechanisms may aid in the search for novel antibiotics against Acinetobacter and other highly antibiotic-resistant pathogens. Acinetobacter baumannii causes many types of severe nosocomial infections; unfortunately, some isolates have acquired resistance to almost every available antibiotic, and treatment options

  15. Multiresistant extended-spectrum beta-lactamase-producing Klebsiella pneumoniae causing an outbreak of nosocomial bloodstream infection.

    Science.gov (United States)

    Gonzalez-Vertiz, A; Alcantar-Curiel, D; Cuauhtli, M; Daza, C; Gayosso, C; Solache, G; Horta, C; Mejia, F; Santos, J I; Alpuche-Aranda, C

    2001-11-01

    This article describes an outbreak of bloodstream infection due to clonal dissemination of multiresistant Klebsiella pneumoniae in a neonatal area, during August 1999, in Mexico City General Hospital. The intestinal tract was the likely reservoir, and intensification of Contact Precaution measures contained the outbreak.

  16. Neutropenia exacerbates infection by Acinetobacter baumannii clinical isolates in a murine wound model

    Directory of Open Access Journals (Sweden)

    Laryssa eGrguric-Smith

    2015-10-01

    Full Text Available The Gram negative coccobacillus Acinetobacter baumannii has become an increasingly prevalent cause of hospital-acquired infections in recent years. The majority of clinical A. baumannii isolates display high-level resistance to antimicrobials, which severely compromises our capacity to care for patients with A. baumannii disease. Neutrophils are of major importance in the host defense against microbial infections. However, the contribution of these cells of innate immunity in host resistance to cutaneous A. baumannii infection has not been directly investigated. Hence, we hypothesized that depletion of neutrophils increases severity of bacterial disease in an experimental A. baumannii murine wound model. In this study, the anti-Ly-6G monoclonal antibody (mAb, 1A8, was used to generate neutropenic mice and the pathogenesis of several A. baumannii clinical isolates on wounded cutaneous tissue was investigated. We demonstrated that neutrophil depletion enhances bacterial burden using colony forming unit determinations. Also, mAb 1A8 reduces global measurements of wound healing in A. baumannii-infected animals. Interestingly, histological analysis of cutaneous tissue excised from A. baumannii-infected animals treated with mAb 1A8 displays enhanced collagen deposition. Furthermore, neutropenia and A. baumannii infection alter pro-inflammatory cytokine release leading to severe microbial disease. Our findings provide a better understanding of the impact of these innate immune cells in controlling A. baumannii skin infections.

  17. Antimicrobial resistance in Acinetobacter baumannii: From bench to bedside

    Science.gov (United States)

    Lin, Ming-Feng; Lan, Chung-Yu

    2014-01-01

    Acinetobacter baumannii (A. baumannii) is undoubtedly one of the most successful pathogens in the modern healthcare system. With invasive procedures, antibiotic use and immunocompromised hosts increasing in recent years, A. baumannii has become endemic in hospitals due to its versatile genetic machinery, which allows it to quickly evolve resistance factors, and to its remarkable ability to tolerate harsh environments. Infections and outbreaks caused by multidrug-resistant A. baumannii (MDRAB) are prevalent and have been reported worldwide over the past twenty or more years. To address this problem effectively, knowledge of species identification, typing methods, clinical manifestations, risk factors, and virulence factors is essential. The global epidemiology of MDRAB is monitored by persistent surveillance programs. Because few effective antibiotics are available, clinicians often face serious challenges when treating patients with MDRAB. Therefore, a deep understanding of the resistance mechanisms used by MDRAB can shed light on two possible strategies to combat the dissemination of antimicrobial resistance: stringent infection control and antibiotic treatments, of which colistin-based combination therapy is the mainstream strategy. However, due to the current unsatisfying therapeutic outcomes, there is a great need to develop and evaluate the efficacy of new antibiotics and to understand the role of other potential alternatives, such as antimicrobial peptides, in the treatment of MDRAB infections. PMID:25516853

  18. Biological effects of carvacrol and cinnamaldehyde on Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Angélique Montagu

    2016-07-01

    Full Text Available Acinetobacter baumannii has emerged as a major cause of nosocomial infections. The ability of A. baumannii to display various resistance mechanisms against antibiotics has transformed it into a successful nosocomial pathogen. The limited number of antibiotics in development and the disengagement of the pharmaceutical industry have prompted the development of innovative strategies. One of these strategies is the use of essential oils, especially aromatic compounds that are potent antibacterial molecules. Among them, the combination of carvacrol and cinnamaldehyde has already demonstrated antibacterial efficacy against A. baumannii. The aim of this study was to determine the biological effects of these two compounds in A. baumannii, describing their effect on the rRNA and gene regulation under environmental stress conditions. Results demonstrated rRNA degradation by the carvacrol/cinnamaldehyde mixture, and this effect was due to carvacrol. Degradation was conserved after encapsulation of the mixture in lipid nanocapsules. Results showed an upregulation of the genes coding for heat shock proteins, such as groES, groEL, dnaK, clpB and the catalase katE, after exposure to carvacrol/cinnamaldehyde mixture. The catalase was upregulated after carvacrol exposure wich is related to an oxidative stress. The combination of thiourea (hydroxyl radical scavenger and carvacrol demonstrated a potent bactericidal effect. These results underline the development of defense strategies of the bacteria by synthesis of reactive oxygen species (ROS in response to environmental stress conditions, such as carvacrol.

  19. Characterisation of integrons and antibiotic resistance genes in Danish multiresistant Salmonella enterica Typhimurium DT104

    DEFF Research Database (Denmark)

    Sandvang, Dorthe; Aarestrup, Frank Møller; Jensen, Lars Bogø

    1997-01-01

    The presence and genetic content of integrons was investigated in eight Salmonella enterica Typhimurium DT104 isolates from different pig herds in Denmark. Two different integrons were identified using PCR and sequencing. Each of the integrons carried a single resistance cassette in addition...... to the sul1 and qacE Delta 1 genes characteristic of integrons. The first integron encoded the ant (3 ")-Ia gene that specified resistance to spectinomycin and streptomycin. The second contained the pse-l beta-lactamase gene. All the multiresistant strains contained both integrons. The presence of these two...... integrons did not account for the total phenotypic resistance of all the isolates and does not exclude the presence of other mobile DNA elements....

  20. Characterisation of integrons and antibiotic resistance genes in Danish multiresistant Salmonella enterica Typhimurium DT104

    DEFF Research Database (Denmark)

    Sandvang, Dorthe; Aarestrup, Frank Møller; Jensen, Lars Bogø

    1998-01-01

    The presence and genetic content of integrons was investigated in eight Salmonella enteritica Typhimurium DT104 isolates from different pig herds in Denmark. Two different integrons were identified using PCR and sequencing. Each of the integrons carried a single resistance cassette in addition...... to the sul1 and qacE Delta 1 genes characteristic of integrons. The first integron encoded the ant (3")-Ia gene that specified resistance to spectinomycin and streptomycin. The second contained the pse-1 beta-lactamase gene. All the multiresistant strains contained both integrons. The presence of these two...... integrons did not account for the total phenotypic resistance of all the isolates and does not exclude the presence of other mobile DNA elements....

  1. IS21-558 Insertion Sequences Are Involved in the Mobility of the Multiresistance Gene cfr▿

    Science.gov (United States)

    Kehrenberg, Corinna; Aarestrup, Frank M.; Schwarz, Stefan

    2007-01-01

    During a study of florfenicol-resistant porcine staphylococci from Denmark, the genes cfr and fexA were detected in the chromosomal DNA or on plasmids of Staphylococcus hyicus, Staphylococcus warneri, and Staphylococcus simulans. A novel variant of the phenicol resistance transposon Tn558 was detected on the ca. 43-kb plasmid pSCFS6 in S. warneri and S. simulans isolates. Sequence analysis of a 22,010-bp segment revealed that the new Tn558 variant harbored an additional resistance gene region integrated into the tnpC reading frame. This resistance gene region consisted of the clindamycin exporter gene lsa(B) and the gene cfr for combined resistance to phenicols, lincosamides, oxazolidinones, pleuromutilins, and streptogramin A antibiotics bracketed by IS21-558 insertion sequences orientated in the same direction. A 6-bp target site duplication was detected at the integration site within tnpC. Transpositionally active forms of the IS21-558 element, known as minicircles, were detected by PCR and suggest that this insertion sequence is involved in the mobility of the multiresistance gene cfr. Based on the knowledge of the transposition pathways of IS21-like insertion sequences and the sequence features detected, the resistance gene region of plasmid pSCFS6 is believed to have developed via IS21-558-mediated cointegrate formation. The data obtained in this study identified the multiresistance gene cfr not only in three novel host species but also in a novel genetic context whose further analysis suggested that insertion sequences of the type IS21-558 are likely to be involved in the dissemination of cfr. PMID:17145796

  2. Prevention of bloodstream infections by photodynamic inactivation of multiresistant Pseudomonas aeruginosa in burn wounds

    Science.gov (United States)

    Hashimoto, M. C. E.; Prates, R. A.; Toffoli, D. J.; Courrol, L. C.; Ribeiro, M. S.

    2010-02-01

    Bloodstream infections are potentially life-threatening diseases. They can cause serious secondary infections, and may result in endocarditis, severe sepsis or toxic-shock syndrome. Pseudomonas aeruginosa is an opportunistic pathogen and one of the most important etiological factors responsible for nosocomial infections, mainly in immuno-compromissed hosts, characteristic of patients with severe burns. Its multiresistance to antibiotics produces many therapeutic problems, and for this reason, the development of an alternative method to antibiotic therapy is needed. Photodynamic inactivation (PDI) may be an effective and alternative therapeutic option to prevent bloodstream infections in patients with severe burns. In this study we report the use of PDI to prevent bloodstream infections in mice with third-degree burns. Burns were produced on the back of the animals and they were infected with 109 cfu/mL of multi-resistant (MR) P. aeruginosa. Fifteen animals were divided into 3 groups: control, PDT blue and PDT red. PDT was performed thirty minutes after bacterial inoculation using 10μM HB:La+3 and a light-emitting diode (LED) emitting at λ=460nm+/-20nm and a LED emitting at λ=645 nm+/-10nm for 120s. Blood of mice were colected at 7h, 10h, 15h, 18h and 22h pos-infection (p.i.) for bacterial counting. Control group presented 1×104 cfu/mL in bloodstream at 7h p.i. increasing to 1×106 at 22h, while mice PDT-treated did not present any bacteria at 7h; only at 22h p.i. they presented 1×104cfu/mL. These results suggest that HB:La+3 associated to blue LED or red LED is effective to delay and diminish MR P.aeruginosa bloodstream invasion in third-degree-burned mice.

  3. Isolation of highly active monoclonal antibodies against multiresistant gram-positive bacteria.

    Directory of Open Access Journals (Sweden)

    Friederike S Rossmann

    Full Text Available Multiresistant nosocomial pathogens often cause life-threatening infections that are sometimes untreatable with currently available antibiotics. Staphylococci and enterococci are the predominant Gram-positive species associated with hospital-acquired infections. These infections often lead to extended hospital stay and excess mortality. In this study, a panel of fully human monoclonal antibodies was isolated from a healthy individual by selection of B-cells producing antibodies with high opsonic killing against E. faecalis 12030. Variable domains (VH and VL of these immunoglobulin genes were amplified by PCR and cloned into an eukaryotic expression vector containing the constant domains of a human IgG1 molecule and the human lambda constant domain. These constructs were transfected into CHO cells and culture supernatants were collected and tested by opsonophagocytic assay against E. faecalis and S. aureus strains (including MRSA. At concentrations of 600 pg/ml, opsonic killing was between 40% and 70% against all strains tested. Monoclonal antibodies were also evaluated in a mouse sepsis model (using S. aureus LAC and E. faecium, a mouse peritonitis model (using S. aureus Newman and LAC and a rat endocarditis model (using E. faecalis 12030 and were shown to provide protection in all models at a concentration of 4 μg/kg per animal. Here we present a method to produce fully human IgG1 monoclonal antibodies that are opsonic in vitro and protective in vivo against several multiresistant Gram-positive bacteria. The monoclonal antibodies presented in this study are significantly more effective compared to another monoclonal antibody currently in clinical trials.

  4. Caspase-11 Plays a Protective Role in Pulmonary Acinetobacter baumannii Infection.

    Science.gov (United States)

    Wang, Wei; Shao, Yue; Li, Shengjun; Xin, Na; Ma, Tingxian; Zhao, Chenghai; Song, Min

    2017-10-01

    Activation of caspase-11 by some Gram-negative bacteria triggers the caspase-1/interleukin 1β (IL-1β) pathway, independent of canonical inflammasomes. Acinetobacter baumannii is a Gram-negative, conditionally pathogenic bacterium that can cause severe pulmonary infection in hospitalized patients. A. baumannii was revealed to activate canonical and noncanonical inflammasome pathways in bone marrow-derived macrophages (BMDMs). Pulmonary infection of caspase-11 -/- mice with A. baumannii showed that caspase-11 deficiency impaired A. baumannii clearance, exacerbated pulmonary pathological changes, and enhanced susceptibility to A. baumannii These data indicate that the caspase-11-mediated innate immune response plays a crucial role in defending against A. baumannii . Copyright © 2017 American Society for Microbiology.

  5. Potential of a lytic bacteriophage to disrupt Acinetobacter baumannii biofilms in vitro.

    Science.gov (United States)

    Liu, Yannan; Mi, Zhiqiang; Niu, Wenkai; An, Xiaoping; Yuan, Xin; Liu, Huiying; Wang, Yong; Feng, Yuzhong; Huang, Yong; Zhang, Xianglilan; Zhang, Zhiyi; Fan, Hang; Peng, Fan; Li, Puyuan; Tong, Yigang; Bai, Changqing

    2016-10-01

    The ability of Acinetobacter baumannii to form biofilms and develop antibiotic resistance makes it difficult to control infections caused by this bacterium. In this study, we explored the potential of a lytic bacteriophage to disrupt A. baumannii biofilms. The potential of the lytic bacteriophage to disrupt A. baumannii biofilms was assessed by performing electron microscopy, live/dead bacterial staining, crystal violet staining and by determining adenosine triphosphate release. The bacteriophage inhibited the formation of and disrupted preformed A. baumannii biofilms. Results of disinfection assay showed that the lytic bacteriophage lysed A. baumannii cells suspended in blood or grown on metal surfaces. These results suggest the potential of the lytic bacteriophage to disrupt A. baumannii biofilms.

  6. Comparative Genomic Analysis of Rapid Evolution of an Extreme-Drug-Resistant Acinetobacter baumannii Clone

    DEFF Research Database (Denmark)

    Tan, Sean Yang-Yi; Chua, Song Lin; Liu, Yang

    2013-01-01

    , comparative genomics has been employed to analyze the rapid evolution of an EDR Acinetobacter baumannii clone from the intensive care unit (ICU) of Rigshospitalet at Copenhagen. Two resistant A. baumannii strains, 48055 and 53264, were sequentially isolated from two individuals who had been admitted to ICU...... within a 1-month interval. Multilocus sequence typing indicates that these two isolates belonged to ST208. The A. baumannii 53264 strain gained colistin resistance compared with the 48055 strain and became an EDR strain. Genome sequencing indicates that A. baumannii 53264 and 48055 have almost identical...... genomes—61 single-nucleotide polymorphisms (SNPs) were found between them. The A. baumannii 53264 strain was assembled into 130 contigs, with a total length of 3,976,592 bp with 38.93% GC content. The A. baumannii 48055 strain was assembled into 135 contigs, with a total length of 4,049,562 bp with 39...

  7. Severe Acinetobacter baumannii Sepsis Is Associated With Elevation of Pentraxin 3

    Science.gov (United States)

    2014-09-01

    Severe Acinetobacter baumannii Sepsis Is Associated with Elevation of Pentraxin 3 Patrick M. Ketter,a M. Neal Guentzel,a Beverly Schaffer,b Maryanne... Acinetobacter baumannii is among the most prevalent bacterial pathogens associated with trauma-related wound and bloodstream infections. Although septic shock...REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Severe Acinetobacter baumannii Sepsis Is Associated With Elevation of Pentraxin 3. 5a

  8. Antimicrobial Activity of Nanoemulsion in Combination with Cetylpyridinium Chloride in Multidrug-Resistant Acinetobacter baumannii

    Science.gov (United States)

    2013-08-01

    cetylpyridinium chloride in multidrug-resistant Acinetobacter baumannii . 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Hwang...with Cetylpyridinium Chloride in Multidrug-Resistant Acinetobacter baumannii Yoon Y. Hwang,a Karthikeyan Ramalingam,b Diane R. Bienek,a Valerie Lee,b...San Antonio, Texas, USAb; and Army Institute of Surgical Research, Fort Sam Houston, Texas, USAc Acinetobacter baumannii has emerged as a serious

  9. The contribution of nutrient metal acquisition and metabolism to Acinetobacter baumannii survival within the host

    OpenAIRE

    Brittany L Mortensen; Eric P Skaar

    2013-01-01

    Acinetobacter baumannii is a significant contributor to intensive care unit (ICU) mortality causing numerous types of infection in this susceptible ICU population, most notably ventilator-associated pneumonia. The substantial disease burden attributed to A. baumannii and the rapid acquisition of antibiotic resistance make this bacterium a serious health care threat. A. baumannii is equipped to tolerate the hostile host environment through modification of its metabolism and nutritional needs. ...

  10. A Case of Community-Acquired Pneumonia Caused by Multidrug-Resistant Acinetobacter baumannii in Korea.

    Science.gov (United States)

    Son, Young Woong; Jung, In Young; Ahn, Mi Young; Jeon, Yong Duk; Ann, Hea Won; Ahn, Jin Young; Ku, Nam Su; Han, Sang Hoon; Choi, Jun Young; Song, Young Goo; Kim, June Myung

    2017-12-01

    Acinetobacter baumannii is an aerobic Gram-negative coccobacillus that causes nosocomial pneumonia in patients on mechanical ventilation or previously treated with broad-spectrum antibiotics. Nevertheless, community-acquired pneumonia (CAP) caused by A. baumannii, especially multi-drug resistant (MDR) strains, is rare. We experienced the first case of CAP caused by MDR A. baumannii in Korea in a 78-year-old man. This case shows that MDR A. baumannii can cause CAP in Korea. Copyright © 2017 by The Korean Society of Infectious Diseases and Korean Society for Chemotherapy.

  11. Clinical and molecular epidemiology of Acinetobacter baumannii bloodstream infections in an endemic setting.

    Science.gov (United States)

    Marchaim, Dror; Levit, Dana; Zigron, Roy; Gordon, Michal; Lazarovitch, Tsillia; Carrico, Joao A; Chalifa-Caspi, Vered; Moran-Gilad, Jacob

    2017-03-01

    The transmission dynamics of Acinetobacter baumannii in endemic settings, and the relation between microbial properties and patients' clinical outcomes, are yet obscure and hampered by insufficient metadata. Of 20 consecutive patients with A. baumannii bloodstream infection that were thoroughly analyzed at a single center, at least one transmission opportunity was evident for 85% of patients. This implies that patient-to-patient transmission is the major mode of A. baumannii acquisitions in health facilities. Moreover, all patients who died immediately (baumannii ST457 lineage compared with other strains.

  12. Interaction of Acinetobacter baumannii 19606 and 1656-2 with Acanthamoeba castellanii.

    Science.gov (United States)

    Tamang, Migma Dorji; Kim, Shukho; Kim, Sung-Min; Kong, Hyun-Hee; Kim, Jungmin

    2011-10-01

    Acinetobacter baumannii is virtually avirulent for healthy people but maintains a high virulence among critically ill patients or immuno-compromised individuals. The ability of A. baumannii to adhere to cells and persist on surfaces as biofilms could be central to its pathogenicity. In the present study, we compared the virulence of the A. baumannii 1656-2 clinical strain, which is able to form a thick biofilm, with the virulence of the A. baumannii type strain (ATCC 19606(T)). Acanthamoeba castellanii, a single-celled organism, was used as the host model system to study the virulence of A. baumannii. Compared to A. baumannii ATCC 19606(T), A. baumannii 1656-2 exhibited a higher ability to adhere and invade A. castellanii cells and had a higher killing rate of A. castellanii cells. Furthermore, co-incubation of the amoeba cells and the cell-free supernatant of A. baumannii resulted in the cell death of the amoebae. Heat inactivation or proteinase K treatment of the supernatant did not eliminate its cytotoxicity, suggesting heat stable non-protein factors are responsible for its cytotoxicity to A. castellanii cells. In conclusion, this study for the first time has revealed the capacity of the A. baumannii strain and/or its metabolic products to induce cytotoxicity in A. castellanii cells.

  13. Prolonged and high dosage of tigecycline - successful treatment of spondylodiscitis caused by multidrug-resistant Acinetobacter baumannii: a case report.

    Science.gov (United States)

    Tsachouridou, Olga; Georgiou, Adamantini; Nanoudis, Sideris; Chrysanthidis, Theofilos; Loli, Georgia; Morfesis, Petros; Zebekakis, Pantelis; Metallidis, Symeon

    2017-07-08

    The incidence of infectious spondylodiscitis has been increasing over the last few years. This reflects the expanding elderly and immunocompromised populations and the rising implementation of invasive spinal procedures. Infection may be inoculated into the disc space directly during invasive spinal procedures. Osteomyelitis caused by Acinetobacter species is rare and mainly caused by multidrug-resistant strains. We present the case of a 72-year-old Greek woman with postoperative spondylodiscitis caused by a multidrug-resistant Acinetobacter baumannii strain that was successfully treated, after she declined surgical treatment, with prolonged and high dosage of tigecycline. She received intravenously administered tigecycline 200 mg per day for 60 days and then 100 mg per day for a total of 102 days and was infection-free. We reviewed the literature on the role of Acinetobacter baumannii as a cause of osteomyelitis, emphasizing the difficulty of treatment and the potential role of tigecycline in conservative treatment of the infection. We believe that 102 days in total is the longest time that any patient has received tigecycline in the literature, thus our patient is a unique case of successful treatment of spondylodiscitis.

  14. Characterization of newly isolated lytic bacteriophages active against Acinetobacter baumannii.

    Science.gov (United States)

    Merabishvili, Maia; Vandenheuvel, Dieter; Kropinski, Andrew M; Mast, Jan; De Vos, Daniel; Verbeken, Gilbert; Noben, Jean-Paul; Lavigne, Rob; Vaneechoutte, Mario; Pirnay, Jean-Paul

    2014-01-01

    Based on genotyping and host range, two newly isolated lytic bacteriophages, myovirus vB_AbaM_Acibel004 and podovirus vB_AbaP_Acibel007, active against Acinetobacter baumannii clinical strains, were selected from a new phage library for further characterization. The complete genomes of the two phages were analyzed. Both phages are characterized by broad host range and essential features of potential therapeutic phages, such as short latent period (27 and 21 min, respectively), high burst size (125 and 145, respectively), stability of activity in liquid culture and low frequency of occurrence of phage-resistant mutant bacterial cells. Genomic analysis showed that while Acibel004 represents a novel bacteriophage with resemblance to some unclassified Pseudomonas aeruginosa phages, Acibel007 belongs to the well-characterized genus of the Phikmvlikevirus. The newly isolated phages can serve as potential candidates for phage cocktails to control A. baumannii infections.

  15. Characterization of newly isolated lytic bacteriophages active against Acinetobacter baumannii.

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    Maia Merabishvili

    Full Text Available Based on genotyping and host range, two newly isolated lytic bacteriophages, myovirus vB_AbaM_Acibel004 and podovirus vB_AbaP_Acibel007, active against Acinetobacter baumannii clinical strains, were selected from a new phage library for further characterization. The complete genomes of the two phages were analyzed. Both phages are characterized by broad host range and essential features of potential therapeutic phages, such as short latent period (27 and 21 min, respectively, high burst size (125 and 145, respectively, stability of activity in liquid culture and low frequency of occurrence of phage-resistant mutant bacterial cells. Genomic analysis showed that while Acibel004 represents a novel bacteriophage with resemblance to some unclassified Pseudomonas aeruginosa phages, Acibel007 belongs to the well-characterized genus of the Phikmvlikevirus. The newly isolated phages can serve as potential candidates for phage cocktails to control A. baumannii infections.

  16. PREVALENCE OF ACINETOBACTER BAUMANNII ISOLATED FROM CLINICAL SPECIMENS IN ADAM MALIK HOSPITAL

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    Evita Mayasari

    2014-05-01

    Full Text Available AbstrakAcinetobacter baumannii merupakan spesies Acinetobacter spp. tersering diisolasi darimanusia, dan lebih sering dijumpai pada infeksi nosokomial dibandingkan dengan infeksi dikomunitas. Eksistensi bakteri ini di lingkungan terkait dengan keragaman reservoir, kemampuanmemperoleh gen pembawa sifat resisten antimikroba, dan sifat resisten terhadap pengeringan.Infeksi disebabkan strain A.baumannii yang resisten terhadap banyak antibiotik tidak mudahdikendalikan dan menjadi permasalahan di berbagai negara. Penelitian ini bertujuan untukmengetahui prevalensi A.baumannii dari spesimen klinis di instalasi mikrobiologi klinik RSUPHaji Adam Malik serta pola kepekaannya terhadap berbagai antibiotik. Identifikasi dan ujikepekaan menggunakan mesin otomatis Vitek 2 dengan Advanced Expert System (AES.Penelitian ini menemukan 644/3693 (17,44% isolat A.baumannii dari berbagai spesimen klinis.A.baumannii paling banyak diisolasi dari spesimen dahak. Penelitian ini menemukan 147/644(23% bahwa isolat carbapenem-resistent A.baumannii (imipenem dan meropenem. Sebagianbesar isolat sensitif terhadap colistin, amikacin dan tigecycline. Prevalensi A.baumanni yangditemukan pada penelitian ini adalah rendah namun resistensinya tinggi terhadap antibiotikterutama golongan penicillin, cephalosporin dan fluoroquinolon.AbstractAcinetobacter baumannii is the most frequent species of Acinetobacter spp. isolated fromhumans and more common in nosocomial infection than it is in community acquired infection.A.baumannii existence in environment is associated with the diversity of its reservoirs, itscapacity to accumulate genes of antimicrobial resistence, and its resistence to desiccation.Infection of Multidrug resistent (MDR strain of A.baumannii is not easy to manage and it hasbecome a problem in many countries. The aim of this retrospective study was to investigatethe prevalence of A.baumannii from routine clinical specimens sent to clinical microbiologylaboratory RSUP HAM

  17. Osmotic Compounds Enhance Antibiotic Efficacy against Acinetobacter baumannii Biofilm Communities.

    Science.gov (United States)

    Falghoush, Azeza; Beyenal, Haluk; Besser, Thomas E; Omsland, Anders; Call, Douglas R

    2017-10-01

    Biofilm-associated infections are a clinical challenge, in part because a hydrated matrix protects the bacterial community from antibiotics. Herein, we evaluated how different osmotic compounds (maltodextrin, sucrose, and polyethylene glycol [PEG]) enhance antibiotic efficacy against Acinetobacter baumannii biofilm communities. Established (24-h) test tube biofilms (strain ATCC 17978) were treated with osmotic compounds in the presence or absence of 10× the MIC of different antibiotics (50 μg/ml tobramycin, 20 μg/ml ciprofloxacin, 300 μg/ml chloramphenicol, 30 μg/ml nalidixic acid, or 100 μg/ml erythromycin). Combining antibiotics with hypertonic concentrations of the osmotic compounds for 24 h reduced the number of biofilm bacteria by 5 to 7 log ( P baumannii strains were similarly treated with 400-Da PEG and tobramycin, resulting in a mean 2.7-log reduction in recoverable bacteria compared with tobramycin treatment alone. Multivariate regression models with data from different osmotic compounds and nine antibiotics demonstrated that the benefit from combining hypertonic treatments with antibiotics is a function of antibiotic mass and lipophilicity ( r 2 > 0.82; P baumannii and Escherichia coli K-12. Augmenting topical antibiotic therapies with a low-mass hypertonic treatment may enhance the efficacy of antibiotics against wound biofilms, particularly when using low-mass hydrophilic antibiotics. IMPORTANCE Biofilms form a barrier that protects bacteria from environmental insults, including exposure to antibiotics. We demonstrated that multiple osmotic compounds can enhance antibiotic efficacy against Acinetobacter baumannii biofilm communities, but viscosity is a limiting factor, and the most effective compounds have lower molecular mass. The synergism between osmotic compounds and antibiotics is also dependent on the hydrophobicity and mass of the antibiotics. The statistical models presented herein provide a basis for predicting the optimal combination of

  18. Pregnancy and Perinatal Outcomes Associated with Acinetobacter baumannii Infection

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    Mai He

    2013-05-01

    Full Text Available Objective - To determine perinatal and pregnancy outcomes of Acinetobacter baumannii infection using clinicopathologic material from pregnant women, neonates, and perinatal postmortem examinations with positive cultures. Study Design - This is a retrospective record review with placental and postmortem examination. Results - During a 5-year period, 40 positive cultures were found. Three pregnancies with positive cultures close in the peripartum period were all associated with adverse outcomes including spontaneous abortion, preterm labor, and one full-term birth with histological chorioamnionitis. Two positive cultures were found in preterm neonates in the neonatal intensive care unit. Two of three cases of perinatal death grew pure cultures from blood and/or fetal tissue with placental or fetal examination demonstrating evidence of infection/inflammation with fetal inflammatory response. Conclusion - This is the first case series report of A. baumannii-positive cultures in maternal, fetal, and neonatal specimen, with histopathologic evidence of infection. The results suggest a significant role of A. baumannii infection in adverse pregnancy and perinatal outcomes.

  19. Evaluation of Parameters for High Efficiency Transformation of Acinetobacter baumannii.

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    Yildirim, Suleyman; Thompson, Mitchell G; Jacobs, Anna C; Zurawski, Daniel V; Kirkup, Benjamin C

    2016-02-25

    Acinetobacter baumannii is an emerging, nosocomial pathogen that is poorly characterized due to a paucity of genetic tools and methods. While whole genome sequence data from several epidemic and environmental strains have recently become available, the functional characterization of genes is significantly lagging. Efficient transformation is one of the first steps to develop molecular tools that can be used to address these shortcomings. Here we report parameters allowing high efficiency transformation of A. baumannii. Using a multi-factorial experimental design we found that growth phase, voltage, and resistance all significantly contribute to transformation efficiency. The highest efficiency (4.3 × 10(8) Transformants/μg DNA) was obtained at the stationary growth phase of the bacterium (OD 6.0) using 25 ng of plasmid DNA under 100 Ohms resistance and 1.7 kV/cm voltage. The optimized electroporation parameters reported here provide a useful tool for genetic manipulation of A. baumannii.

  20. Stereochemical insignificance discovered in Acinetobacter baumannii quorum sensing.

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    Amanda L Garner

    Full Text Available Stereochemistry is a key aspect of molecular recognition for biological systems. As such, receptors and enzymes are often highly stereospecific, only recognizing one stereoisomer of a ligand. Recently, the quorum sensing signaling molecules used by the nosocomial opportunistic pathogen, Acinetobacter baumannii, were identified, and the primary signaling molecule isolated from this species was N-(3-hydroxydodecanoyl-L-homoserine lactone. A plethora of bacterial species have been demonstrated to utilize 3-hydroxy-acylhomoserine lactone autoinducers, and in virtually all cases, the (R-stereoisomer was identified as the natural ligand and exhibited greater autoinducer activity than the corresponding (S-stereoisomer. Using chemical synthesis and biochemical assays, we have uncovered a case of stereochemical insignificance in A. baumannii and provide a unique example where stereochemistry appears nonessential for acylhomoserine lactone-mediated quorum sensing signaling. Based on previously reported phylogenetic studies, we suggest that A. baumannii has evolutionarily adopted this unique, yet promiscuous quorum sensing system to ensure its survival, particularly in the presence of other proteobacteria.

  1. Acinetobacter baumannii in Localised Cutaneous Mycobacteriosis in Falcons

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    Margit Gabriele Muller

    2010-01-01

    Full Text Available Between May 2007 and April 2009, 29 falcons with identically localized, yellowish discolored cutaneous lesions in the thigh and lateral body wall region were presented at Abu Dhabi Falcon Hospital. Out of 18 falcons integrated in this study, 16 tested positive to Mycobacterium. avium complex. The 2 negative falcons tested positive in the Mycobacterium genus PCR. Moreover, 1 falcon tested positive to M. avium. paratuberculosis in tissue samples by PCR. In all cases, blood and fecal samples tested negative. In the acid-fast stain, all samples showed the for mycobacteriosis typical rods. Moreover, in 13 samples Acinetobacter baumannii was detected by PCR and proven by DNA sequencing. Clinical features included highly elevated WBCs, heterophilia, lymphocytopenia, monocytosis, severe anemia and weight loss. A. baumannii, a gram-negative bacillus with the ability to integrate foreign DNA, has emerged as one of the major multidrug resistant bacteria. In veterinary medicine, it has so far been detected in dogs, cats, horses and wild birds. To the authors' knowledge, this is the first report of an A. baumannii infection in falcons and of a veterinary Mycobacterium-Acinetobacter coinfection.

  2. Multiresistant opportunistic pathogenic bacteria isolated from polluted rivers and first detection of nontuberculous mycobacteria in the Algerian aquatic environment.

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    Djouadi, Lydia Neïla; Selama, Okba; Abderrahmani, Ahmed; Bouanane-Darenfed, Amel; Abdellaziz, Lamia; Amziane, Meriam; Fardeau, Marie-Laure; Nateche, Farida

    2017-08-01

    Opportunistic infections constitute a major challenge for modern medicine mainly because the involved bacteria are usually multiresistant to antibiotics. Most of these bacteria possess remarkable ability to adapt to various ecosystems, including those exposed to anthropogenic activities. This study isolated and identified 21 multiresistant opportunistic bacteria from two polluted rivers, located in Algiers. Cadmium, lead, and copper concentrations were determined for both water samples to evaluate heavy metal pollution. High prevalence of Enterobacteria and non-fermentative Gram-negative rods was found and a nontuberculous Mycobacterium (NTM) strain was isolated. To the best of our knowledge, this is the first detection of NTM in the Algerian environment. The strains were tested for their resistance against 34 antibiotics and 8 heavy metals. Multiple antibiotics and heavy metals resistance was observed in all isolates. The two most resistant strains, identified as Acinetobacter sp. and Citrobacter freundii, were submitted to plasmid curing to determine if resistance genes were plasmid or chromosome encoded. Citrobacter freundii strain P18 showed a high molecular weight plasmid which seems to code for resistance to zinc, lead, and tetracycline, at the same time. These findings strongly suggest that anthropized environments constitute a reservoir for multiresistant opportunistic bacteria and for circulating resistance genes.

  3. Multidrug resistant Acinetobacter baumannii in veterinary medicine--emergence of an underestimated pathogen?

    Science.gov (United States)

    Müller, Stefanie; Janssen, Traute; Wieler, Lothar H

    2014-01-01

    The proportion of multidrug resistant bacteria causing infections in animals has continuously been increasing. While the relevance of ESBL (extended spectrum beta-lactamase)-producing Enterobacteriaceae spp. and MRSA (methicillin resistant Staphylococcus aureus) is unquestionable, knowledge about multidrug resistant Acinetobacter baumannii in veterinary medicine is scarce. This is a worrisome situation, as A. baumannii are isolated from veterinary clinical specimens with rising frequency. The remarkable ability of A. baumannii to develop multidrug resistance and the high risk of transmission are known in human medicine for years. Despite this, data regarding A. baumannii isolates of animal origin are missing. Due to the changing role of companion animals with closer contact between animal and owner, veterinary intensive care medicine is steadily developing. It can be assumed that the number of "high risk" patients with an enhanced risk for hospital acquired infections will be rising simultaneously. Thus, development and spread of multidrug resistant pathogens is envisioned to rise. It is possible, that A. baumannii will evolve into a veterinary nosocomial pathogen similar to ESBL-producing Enterobacteriaceae and MRSA. The lack of attention paid to A. baumannii in veterinary medicine is even more worrying, as first reports indicate a transmission between humans and animals. Essential questions regarding the role of livestock, especially as a potential source of multidrug resistant isolates, remain unanswered. This review summarizes the current knowledge on A. baumannii in veterinary medicine for the first time. It underlines the utmost significance of further investigations of A. baumannii animal isolates, particularly concerning epidemiology and resistance mechanisms.

  4. Tigecycline use in two cases with multidrug-resistant Acinetobacter baumannii meningitis.

    Science.gov (United States)

    Tutuncu, E Ediz; Kuscu, Ferit; Gurbuz, Yunus; Ozturk, Baris; Haykir, Asli; Sencan, Irfan

    2010-09-01

    The treatment of post-surgical meningitis due to multidrug-resistant (MDR) Acinetobacter baumannii is a therapeutic dilemma. The cases of two patients with MDR A. baumannii meningitis secondary to surgical site infections, successfully treated with combination regimens including tigecycline, are presented. Copyright © 2009 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  5. PREVALENCE OF ACINETOBACTER BAUMANNII ISOLATED FROM CLINICAL SPECIMENS IN ADAM MALIK HOSPITAL

    OpenAIRE

    Evita Mayasari; Cherry Siregar

    2014-01-01

    AbstrakAcinetobacter baumannii merupakan spesies Acinetobacter spp. tersering diisolasi darimanusia, dan lebih sering dijumpai pada infeksi nosokomial dibandingkan dengan infeksi dikomunitas. Eksistensi bakteri ini di lingkungan terkait dengan keragaman reservoir, kemampuanmemperoleh gen pembawa sifat resisten antimikroba, dan sifat resisten terhadap pengeringan.Infeksi disebabkan strain A.baumannii yang resisten terhadap banyak antibiotik tidak mudahdikendalikan dan menjadi permasalahan di b...

  6. Cryo-electron tomography analysis of membrane vesicles from Acinetobacter baumannii ATCC19606(T)

    NARCIS (Netherlands)

    Koning, Roman I.; de Breij, Anna; Oostergetel, Gert T.; Nibbering, Peter H.; Koster, Abraham J.; Dijkshoorn, Lenie

    Acinetobacter baumannii is an important nosocomial pathogen responsible for colonization and infection of critically ill patients. Its virulence attributes together with the condition of the host determine the pathogenicity of A. baumannii. These virulence factors may be delivered to host cells by

  7. A case of community-acquired Acinetobacter baumannii meningitis - has the threat moved beyond the hospital?

    NARCIS (Netherlands)

    Lowman, Warren; Kalk, Thomas; Menezes, Colin N.; John, Melanie A.; Grobusch, Martin P.

    2008-01-01

    Acinetobacter baumannii is a prolific nosocomial pathogen renowned for its multidrug-resistant nature. We report a case of community-acquired meningitis due to A. baumannii. The case highlights the potential pathogenicity of this organism and raises concerns that this highly adaptable organism may

  8. Towards an explanation for the success of Acinetobacter baumannii in the human host

    NARCIS (Netherlands)

    Breij, Anastasia (Anna)

    2012-01-01

    Acinetobacter baumannii is an important nosocomial pathogen responsible for outbreaks of infection worldwide. The studies presented in this thesis aimed to gain further insight into the bacterial and host factors associated with the pathogenesis of A. baumannii to seek an explanation for the

  9. Complete genome sequence of the multiresistant taxonomic outlier Pseudomonas aeruginosa PA7.

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    Paul H Roy

    2010-01-01

    Full Text Available Pseudomonas aeruginosa PA7 is a non-respiratory human isolate from Argentina that is multiresistant to antibiotics. We first sequenced gyrA, gyrB, parC, parE, ampC, ampR, and several housekeeping genes and found that PA7 is a taxonomic outlier. We report here the complete sequence of the 6,588,339 bp genome, which has only about 95% overall identity to other strains. PA7 has multiple novel genomic islands and a total of 51 occupied regions of genomic plasticity. These islands include antibiotic resistance genes, parts of transposons, prophages, and a pKLC102-related island. Several PA7 genes not present in PAO1 or PA14 are putative orthologues of other Pseudomonas spp. and Ralstonia spp. genes. PA7 appears to be closely related to the known taxonomic outlier DSM1128 (ATCC9027. PA7 lacks several virulence factors, notably the entire TTSS region corresponding to PA1690-PA1725 of PAO1. It has neither exoS nor exoU and lacks toxA, exoT, and exoY. PA7 is serotype O12 and pyoverdin type II. Preliminary proteomic studies indicate numerous differences with PAO1, some of which are probably a consequence of a frameshift mutation in the mvfR quorum sensing regulatory gene.

  10. Multiresistant Salmonella ohio infections at the University Hospital of the West Indies.

    Science.gov (United States)

    Macfarlane, D E

    1986-04-01

    During 1982-83 there was a substantial increase in the number of S. ohio infections at the University Hospital of the West Indies, which coincided with the appearance of strains resistant to chloramphenicol, cotrimoxazole, ampicillin, neomycin and carbenicillin. Multiresistant strains of S. ohio accounted for 19.3% of all salmonella isolates during this period and all of 40 strains tested were able to transfer resistance determinants to E. coli K12 J 53-2. S. ohio was cultured from stool (60), blood (5), wounds and abscesses (4) and postmortem material (2). Eighty-six per cent of S. ohio infections occurred in children of 3 years old or less. There was a high incidence of gastroenteritis in malnourished children, a 14% incidence of localizing infections and a 7% incidence of septicaemia. Two infants with severe gastroenteritis and bronchopneumonia died. There were a number of unusual infections including two cases of septicaemia in children receiving chloramphenicol for Haemophilus influenzae meningitis, a scrotal abscess secondary to extravasation of urine and infected scabies in a child with marasmic kwashiorkor.

  11. Susceptibility of clinical isolates of multiresistant Pseudomonas aeruginosa to a hospital disinfectant and molecular typing

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    Célia Maria Carvalho Pereira Araujo Romão

    2005-08-01

    Full Text Available The aim of this study was to evaluate the susceptibility of 35 resistant Pseudomonas aeruginosa clinical isolates to a quaternary ammonium hospital disinfectant. The methodology was the AOAC Use-Dilution Test, with disinfectant at its use-concentration. In addition, the chromosomal DNA profile of the isolates were determined by macro-restriction pulsed field gel electrophoresis (PFGE method aiming to verify the relatedness among them and the behavior of isolates from the same group regarding the susceptibility to the disinfectant. Seventy one percent of the isolates were multiresistant to antibiotics and 43% showed a reduced susceptibility to the disinfectant. The PFGE methodology detected 18 major clonal groups. We found isolates with reduced susceptibility to the disinfectant and we think that these are worrying data that should be further investigated including different organisms and chemical agents in order to demonstrate that microorganisms can be destroyed by biocide as necessary. We also found strains of the same clonal groups showing different susceptibility to the disinfectant. This is an interesting observation considering that only few works are available about this subject. PFGE profile seems not to be a reliable marker for resistance to disinfectants.

  12. Effect of vancomycin on the proteome of the multiresistant Enterococcus faecium SU18 strain.

    Science.gov (United States)

    Ramos, Sónia; Chafsey, Ingrid; Silva, Nuno; Hébraud, Michel; Santos, Hugo; Capelo-Martinez, José-Luis; Poeta, Patrícia; Igrejas, Gilberto

    2015-01-15

    Enterococci are not highly pathogenic bacteria, but the incidence of vancomycin resistance among clinical isolates of this microbial group is steadily increasing, posing a threat to public health. Vancomycin-resistant enterococci are currently some of the most recalcitrant hospital-associated pathogens against which new therapies are urgently needed. To understand the molecular mechanisms of bacterial resistance to glycopeptides, we obtained proteomic profiles of the vancomycin-resistant Enterococcus faecium SU18 strain treated with and without vancomycin. Fourteen proteins were differentially expressed in SU18, seven of which were up-regulated and seven down-regulated. Proteins involved in the vancomycin resistance mechanism, such as the VanA protein, VanA ligase, VanR and D-Ala-D-Ala dipeptidase, were up-regulated in the presence of vancomycin, while metabolism-related proteins, such as triosephosphate isomerase, guanine monophosphate synthase and glyceraldehyde-3-phosphate dehydrogenase were down-regulated. Overall the compensatory response of SU18 to antibiotics is to alter expression of proteins related to antibiotic resistance, cell wall formation and energy metabolism. Some of the differentially expressed proteins might enhance antimicrobial activity and are now being investigated as potential therapeutic drug targets in other pathogenic bacteria. This study highlights the power of proteomics in the study of differential protein expression in a multiresistant Enterococcus faecium strain when subjected to vancomycin stress. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. High frequency of multiresistant coagulase-positive Staphylococcus aureus found in slaughter pigs in Uruguay.

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    Meyer, Cornelia; Fredriksson-Ahomaa, Maria; Stüber, Elisabeth; Thiel, Susanne; Märtlbauer, Erwin

    2012-01-01

    Staphylococcus aureus are a hazard to human health since they can cause infections and food poisoning. Antimicrobial resistant strains render the treatment of infections problematic and contribute to the spread of antimicrobial resistance. They are therefore of great public concern. This study determined the resistance pattern of coagulase-positive S. aureus (CPSA) isolated from nasal swabs of 100 slaughter pigs from one farm in Uruguay. Out of 69 animals, 71 CPSA were collected. Minimum inhibitory concentrations of 20 antimicrobials were determined using the broth microdilution method in accordance with CLSI recommendations. No methicillin-resistant S. aureus were detected. All CPSA were resistant to three or more classes of antimicrobials (i.e., multiresistant), whereby all CPSA were resistant to spectinomycin. Most of the isolates (46%) were resistant to six classes of antimicrobials. Almost all isolates were resistant to penicillin (99%), ampicillin (99%), gentamicin (96%), tetracycline (90%), and tilmicosin (87%). Very high resistance rates were observed against erythromycin (77%) and clindamycin (70%). High resistance was observed against tiamulin (40%), enrofloxacin (31%), and florfenicol (23%) and low resistance was observed against amoxicillin/clavulanic acid (4%). All CPSA isolates were mecA negative. The results of the present study could be related to an overuse of antimicrobials in pig production and should encourage veterinarians and pig holders to practice a controlled administration of chemotherapeutics in pig husbandry.

  14. Complete Genome Sequence of the Multiresistant Taxonomic Outlier Pseudomonas aeruginosa PA7

    Science.gov (United States)

    Roy, Paul H.; Tetu, Sasha G.; Larouche, André; Elbourne, Liam; Tremblay, Simon; Ren, Qinghu; Dodson, Robert; Harkins, Derek; Shay, Ryan; Watkins, Kisha; Mahamoud, Yasmin; Paulsen, Ian T.

    2010-01-01

    Pseudomonas aeruginosa PA7 is a non-respiratory human isolate from Argentina that is multiresistant to antibiotics. We first sequenced gyrA, gyrB, parC, parE, ampC, ampR, and several housekeeping genes and found that PA7 is a taxonomic outlier. We report here the complete sequence of the 6,588,339 bp genome, which has only about 95% overall identity to other strains. PA7 has multiple novel genomic islands and a total of 51 occupied regions of genomic plasticity. These islands include antibiotic resistance genes, parts of transposons, prophages, and a pKLC102-related island. Several PA7 genes not present in PAO1 or PA14 are putative orthologues of other Pseudomonas spp. and Ralstonia spp. genes. PA7 appears to be closely related to the known taxonomic outlier DSM1128 (ATCC9027). PA7 lacks several virulence factors, notably the entire TTSS region corresponding to PA1690-PA1725 of PAO1. It has neither exoS nor exoU and lacks toxA, exoT, and exoY. PA7 is serotype O12 and pyoverdin type II. Preliminary proteomic studies indicate numerous differences with PAO1, some of which are probably a consequence of a frameshift mutation in the mvfR quorum sensing regulatory gene. PMID:20107499

  15. Multi-resistive reduced graphene oxide diode with reversible surface electrochemical reaction induced carrier control.

    Science.gov (United States)

    Seo, Hyungtak; Ahn, Seungbae; Kim, Jinseo; Lee, Young-Ahn; Chung, Koo-Hyun; Jeon, Ki-Joon

    2014-07-10

    The extended application of graphene-based electronic devices requires a bandgap opening in order to realize the targeted device functionality. Since the bandgap tuning of pristine graphene is limited to 360 meV, the chemical modification of graphene is considered essential to achieve a large bandgap opening at the expense of electrical properties degradation. Reduced graphene oxide (RGO) has attracted significant interest for fabricating graphene-based semiconductors since it has several advantages over other forms of chemically modified graphene; such as tunable bandgap opening, decent electrical properties, and easy synthesis. Because of the reduced bonding nature of RGO, the role of metastable oxygen in the RGO matrix is recently highlighted and it may offer emerging ionic devices. In this study, we show that multi-resistivity RGO/n-Si diodes can be obtained by controlling the RGO thickness at a nanometer scale. This is made possible by (1) a metastable lattice-oxygen drift within bulk RGO and (2) electrochemical ambient hydroxyl (OH) formation at the RGO surface. The effect demonstrated in a p-RGO/n-Si heterojunction diode is equivalent to electrochemically driven reversible electronic manipulation and therefore provides an important basis for the application of O bistability in RGO for chemical sensors and electrocatalysis.

  16. Efficacy of the small molecule inhibitor of Lipid II BAS00127538 against Acinetobacter baumannii

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    de Leeuw EPH

    2014-08-01

    Full Text Available Erik PH de Leeuw Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, USA Objective: To test the activity of a small molecule compound that targets Lipid II against Acinetobacter baumannii. Methods: Susceptibility to small molecule Lipid II inhibitor BAS00127538 was assessed using carbapenem- and colistin-resistant clinical isolates of A. baumannii. In addition, synergy between colisitin and this compound was assessed. Results: Small molecule Lipid II inhibitor BAS00127538 potently acts against A. baumannii and acts synergistically with colistin. Conclusion: For the first time, a compound that targets Lipid II is described that acts against multi-drug resistant isolates of A. baumannii. The synergy with colistin warrants further lead development of BAS00127538. Keywords: Lipid II, Acinetobacter baumannii, drug development

  17. Clinical and Epidemiological Significance of Carbapenem Resistance in Acinetobacter baumannii Infections.

    Science.gov (United States)

    Tal-Jasper, Ruthy; Katz, David E; Amrami, Nadav; Ravid, Dor; Avivi, Dori; Zaidenstein, Ronit; Lazarovitch, Tsilia; Dadon, Mor; Kaye, Keith S; Marchaim, Dror

    2016-05-01

    Carbapenems are considered the treatment of choice for Acinetobacter baumannii infections. Many facilities implement preventive measures toward only carbapenem-resistant A. baumannii (CRAB). However, the independent role of the carbapenem resistance determinant on patient outcomes remains controversial. In a 6-year analysis of adults with A. baumannii bloodstream infection (BSI), the outcomes of 149 CRAB isolates were compared to those of 91 patients with carbapenem-susceptible A. baumannii In bivariable analyses, CRAB BSIs were significantly associated with worse outcomes and with a delay in the initiation of appropriate antimicrobial therapy (DAAT). However, in multivariable analyses, carbapenem resistance status was no longer associated with poor outcomes, while DAAT remained an independent predictor. The epidemiological significance of A. baumannii should not be determined by its resistance to carbapenems. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  18. Biology of Acinetobacter baumannii: Pathogenesis, Antibiotic Resistance Mechanisms, and Prospective Treatment Options

    Science.gov (United States)

    Lee, Chang-Ro; Lee, Jung Hun; Park, Moonhee; Park, Kwang Seung; Bae, Il Kwon; Kim, Young Bae; Cha, Chang-Jun; Jeong, Byeong Chul; Lee, Sang Hee

    2017-01-01

    Acinetobacter baumannii is undoubtedly one of the most successful pathogens responsible for hospital-acquired nosocomial infections in the modern healthcare system. Due to the prevalence of infections and outbreaks caused by multi-drug resistant A. baumannii, few antibiotics are effective for treating infections caused by this pathogen. To overcome this problem, knowledge of the pathogenesis and antibiotic resistance mechanisms of A. baumannii is important. In this review, we summarize current studies on the virulence factors that contribute to A. baumannii pathogenesis, including porins, capsular polysaccharides, lipopolysaccharides, phospholipases, outer membrane vesicles, metal acquisition systems, and protein secretion systems. Mechanisms of antibiotic resistance of this organism, including acquirement of β-lactamases, up-regulation of multidrug efflux pumps, modification of aminoglycosides, permeability defects, and alteration of target sites, are also discussed. Lastly, novel prospective treatment options for infections caused by multi-drug resistant A. baumannii are summarized. PMID:28348979

  19. Glucose availability enhances lipopolysaccharide production and immunogenicity in the opportunistic pathogen Acinetobacter baumannii.

    Science.gov (United States)

    Rossi, Elio; Longo, Francesca; Barbagallo, Marialuisa; Peano, Clelia; Consolandi, Clarissa; Pietrelli, Alessandro; Jaillon, Sebastian; Garlanda, Cecilia; Landini, Paolo

    2016-01-01

    Acinetobacter baumannii can cause sepsis with high mortality rates. We investigated whether glucose sensing might play a role in A. baumannii pathogenesis. We carried out transcriptome analysis and extracellular polysaccharide determination in an A. baumannii clinical isolate grown on complex medium with or without glucose supplementation, and assessed its ability to induce production of inflammatory cytokines in human macrophages. Growth in glucose-supplemented medium strongly enhanced A. baumannii sugar anabolism, resulting in increasing lipopolysaccharide biosynthesis. In addition, glucose induced active shedding of lipopolysaccharide, in turn triggering a strong induction of inflammatory cytokines in human macrophages. Finally, hemolytic activity was strongly enhanced by growth in glucose-supplemented medium. We propose that sensing of exogenous glucose might trigger A. baumannii pathogenesis during sepsis.

  20. Candida spp. airway colonization: A potential risk factor for Acinetobacter baumannii ventilator-associated pneumonia.

    Science.gov (United States)

    Tan, Xiaojiang; Zhu, Song; Yan, Dongxing; Chen, Weiping; Chen, Ruilan; Zou, Jian; Yan, Jingdong; Zhang, Xiangdong; Farmakiotis, Dimitrios; Mylonakis, Eleftherios

    2016-08-01

    This retrospective study was conducted to identify potential risk factors for Acinetobacter baumannii (A. baumannii) ventilator-associated pneumonia (VAP) and evaluate the association between Candida spp. airway colonization and A. baumannii VAP. Intensive care unit (ICU) patients who were on mechanical ventilation (MV) for ≥48 hours were divided into the following groups: patients with and without Candida spp. airway colonization; colonized patients receiving antifungal treatment or not; patients with A. baumannii VAP and those without VAP. Logistic regression analysis and propensity score matching were used to identify factors independently associated with A. baumannii VAP. Among 618 eligible patients, 264 (43%) had Candida spp. airway colonization and 114 (18%) developed A. baumannii VAP. Along with MV for ≥7 days (adjusted odds ratio [aOR] 8.9, 95% confidence intervals [95% CI] 4.9-15.8) and presence of a central venous catheter (aOR 3.2, 95% CI 1.1-9), Candida spp. airway colonization (aOR 2.6, 95% CI 1.6-4.3) was identified as an independent risk factor for A. baumannii VAP. Patients with Candida spp. airway colonization were more likely to develop A. baumannii VAP than non-colonized patients (23% vs 15%, P=.01 and 34% vs. 15%, PCandida spp. airway colonization (43%) and A. baumannii VAP (18%) were common in ICU patients who were on mechanical ventilation for at least 48 hours. Candida spp. airway colonization was an independent risk factor for subsequent A. baumannii VAP. © The Author 2016. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Identification of Acinetobacter baumannii of Human and Animal Origins by a Gene-Specific PCR.

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    Hamouda, Ahmed

    2017-09-01

    Acinetobacter baumannii is a notorious nosocomial pathogen known for its ability to cause severe infections, especially in intensive care units. The identification of a conserved gene encoding a hypothetical protein in A. baumannii isolates but not in other Acinetobacter species during a comparative genomic analysis was reported. For the purpose of this study, we call this gene, A.b_hyp gene. The aim of this study was to report the results of screening for the presence of the A.b_hyp gene in a worldwide collection of well-characterized A. baumannii collected from clinical and animal specimens. A total of 83 clinical, animal, and type strains were used. These comprised 73 A. baumannii isolates of clinical (n = 60) and animal origin (n = 13), and ten type strains, including a positive control strain, A. baumannii ATCC 19606. All isolates were examined by PCR amplification of the A.b_hyp gene. The A.b_hyp gene was detected in 72 isolates (99%) of A. baumannii but one clinical isolate failed to produce an amplicon. The control strain, A. baumannii ATCC 19606, was also positive for this gene. No bands were detected in non-A. baumannii species and therefore the isolates are thought to be negative for the gene. No bands were detected in non-A. baumannii isolates and therefore they are thought to be negative for the gene. The PCR A.b_ hyp method provides evidence that detection of this gene can be used as a reliable, easy, and low-cost biomarker for A. baumannii identification.

  2. Comparative Genomic Analysis of Rapid Evolution of an Extreme-Drug-Resistant Acinetobacter baumannii Clone

    Science.gov (United States)

    Tan, Sean Yang-Yi; Chua, Song Lin; Liu, Yang; Høiby, Niels; Andersen, Leif Percival; Givskov, Michael; Song, Zhijun; Yang, Liang

    2013-01-01

    The emergence of extreme-drug-resistant (EDR) bacterial strains in hospital and nonhospital clinical settings is a big and growing public health threat. Understanding the antibiotic resistance mechanisms at the genomic levels can facilitate the development of next-generation agents. Here, comparative genomics has been employed to analyze the rapid evolution of an EDR Acinetobacter baumannii clone from the intensive care unit (ICU) of Rigshospitalet at Copenhagen. Two resistant A. baumannii strains, 48055 and 53264, were sequentially isolated from two individuals who had been admitted to ICU within a 1-month interval. Multilocus sequence typing indicates that these two isolates belonged to ST208. The A. baumannii 53264 strain gained colistin resistance compared with the 48055 strain and became an EDR strain. Genome sequencing indicates that A. baumannii 53264 and 48055 have almost identical genomes—61 single-nucleotide polymorphisms (SNPs) were found between them. The A. baumannii 53264 strain was assembled into 130 contigs, with a total length of 3,976,592 bp with 38.93% GC content. The A. baumannii 48055 strain was assembled into 135 contigs, with a total length of 4,049,562 bp with 39.00% GC content. Genome comparisons showed that this A. baumannii clone is classified as an International clone II strain and has 94% synteny with the A. baumannii ACICU strain. The ResFinder server identified a total of 14 antibiotic resistance genes in the A. baumannii clone. Proteomic analyses revealed that a putative porin protein was down-regulated when A. baumannii 53264 was exposed to antimicrobials, which may reduce the entry of antibiotics into the bacterial cell. PMID:23538992

  3. The Complete Genome and Phenome of a Community-Acquired Acinetobacter baumannii

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    Farrugia, Daniel N.; Elbourne, Liam D. H.; Hassan, Karl A.; Eijkelkamp, Bart A.; Tetu, Sasha G.; Brown, Melissa H.; Shah, Bhumika S.; Peleg, Anton Y.; Mabbutt, Bridget C.; Paulsen, Ian T.

    2013-01-01

    Many sequenced strains of Acinetobacter baumannii are established nosocomial pathogens capable of resistance to multiple antimicrobials. Community-acquired A. baumannii in contrast, comprise a minor proportion of all A. baumannii infections and are highly susceptible to antimicrobial treatment. However, these infections also present acute clinical manifestations associated with high reported rates of mortality. We report the complete 3.70 Mbp genome of A. baumannii D1279779, previously isolated from the bacteraemic infection of an Indigenous Australian; this strain represents the first community-acquired A. baumannii to be sequenced. Comparative analysis of currently published A. baumannii genomes identified twenty-four accessory gene clusters present in D1279779. These accessory elements were predicted to encode a range of functions including polysaccharide biosynthesis, type I DNA restriction-modification, and the metabolism of novel carbonaceous and nitrogenous compounds. Conversely, twenty genomic regions present in previously sequenced A. baumannii strains were absent in D1279779, including gene clusters involved in the catabolism of 4-hydroxybenzoate and glucarate, and the A. baumannii antibiotic resistance island, known to bestow resistance to multiple antimicrobials in nosocomial strains. Phenomic analysis utilising the Biolog Phenotype Microarray system indicated that A. baumannii D1279779 can utilise a broader range of carbon and nitrogen sources than international clone I and clone II nosocomial isolates. However, D1279779 was more sensitive to antimicrobial compounds, particularly beta-lactams, tetracyclines and sulphonamides. The combined genomic and phenomic analyses have provided insight into the features distinguishing A. baumannii isolated from community-acquired and nosocomial infections. PMID:23527001

  4. Risk factors and outcome analysis of acinetobacter baumannii complex bacteremia in critical patients.

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    Lee, Hao-Yuan; Chen, Chyi-Liang; Wu, Si-Ru; Huang, Chih-Wei; Chiu, Cheng-Hsun

    2014-05-01

    Acinetobacter baumannii complex bacteremia has been identified increasingly in critical patients admitted in ICUs. Notably, A. baumannii complex bacteremia has a high mortality rate, yet the risk factors associated with mortality remain unclear and controversial. Retrospective study. All adult ICUs at a tertiary care medical center. All patients with A. baumannii complex bacteremia admitted in 2009-2010. None. Risk factors for mortality were analyzed. Bacterial isolates were identified by 16S-23S ribosomal RNA intergenic spacer region sequencing for genospecies and genotyped by pulsed-field gel electrophoresis. Carbapenemase genes were detected by polymerase chain reaction and sequencing. A total of 298 patients met the inclusion criteria, including 73 (24.5%) infected by imipenem-resistant A. baumannii complex. The overall 30-day mortality was 33.6% (100 of 298). Imipenem-resistant A. baumannii complex bacteremia specifically showed a high mortality (69.9%) and was associated with prior use of broad-spectrum antibiotics for more than 5 days for treating ventilator-associated pneumonia before the occurrence of bacteremia. Mortality was associated with inappropriate initial antimicrobial therapy, which was correlated with imipenem-resistant A. baumannii complex but not with any specific genospecies. ISAba1-blaOXA-23-ISAba1 (Tn2006) was found in most (66.7%, 40 of 68) imipenem-resistant A. baumannii (genospecies 2) and also spread beyond species border to all imipenem-resistant genospecies 3 (2), 13TU (2), and 10 (1). For critical patients with A. baumannii complex infection, ventilator-associated pneumonia in particular, the selective pressure from prior use of broad-spectrum antibiotics for 5 days or more increased risk of subsequent imipenem-resistant A. baumannii complex bacteremia. To reduce mortality, rapid identification of imipenem-resistant A. baumannii complex and early initiation of appropriate antimicrobial therapy in these high-risk patients are crucial.

  5. The evolutionary history of chromosomal super-integrons provides an ancestry for multiresistant integrons

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    Rowe-Magnus, Dean A.; Guerout, Anne-Marie; Ploncard, Pascaline; Dychinco, Broderick; Davies, Julian; Mazel, Didier

    2001-01-01

    Integrons are genetic elements that acquire and exchange exogenous DNA, known as gene cassettes, by a site-specific recombination mechanism. Characterized gene cassettes consist of a target recombination sequence (attC site) usually associated with a single open reading frame coding for an antibiotic resistance determinant. The affiliation of multiresistant integrons (MRIs), which contain various combinations of antibiotic resistance gene cassettes, with transferable elements underlies the rapid evolution of multidrug resistance among diverse Gram-negative bacteria. Yet the origin of MRIs remains unknown. Recently, a chromosomal super-integron (SI) harboring hundreds of cassettes was identified in the Vibrio cholerae genome. Here, we demonstrate that the activity of its associated integrase is identical to that of the MRI integrase, IntI1. We have also identified equivalent integron superstructures in nine distinct genera throughout the γ-proteobacterial radiation. Phylogenetic analysis revealed that the evolutionary history of the system paralleled that of the radiation, indicating that integrons are ancient structures. The attC sites of the 63 antibiotic-resistance gene cassettes identified thus far in MRIs are highly variable. Strikingly, one-fifth of these were virtually identical to the highly related yet species-specific attC sites of the SIs described here. Furthermore, antimicrobial resistance homologues were identified among the thousands of genes entrapped by these SIs. Because the gene cassettes of SIs are substrates for MRIs, these data identify SIs as the source of contemporary MRIs and their cassettes. However, our demonstration of the metabolic functions, beyond antibiotic resistance and virulence, of three distinct SI gene cassettes indicates that integrons function as a general gene-capture system for bacterial innovation. PMID:11209061

  6. Assessing excess nurse work load generated by multiresistant nosocomial bacteria in intensive care.

    Science.gov (United States)

    Saulnier, F F; Hubert, H; Onimus, T M; Beague, S; Nseir, S; Grandbastien, B; Renault, C Y; Idzik, M; Erb, M P; Durocher, A V

    2001-05-01

    To compare three methods for assessing the excess nurse work load related to recommended procedures for managing nosocomial infections (NI) due to multiresistant bacteria (MRB): two activity scores, the Omega score and the Projet de Recherche en Nursing (PRN) system, and a specific evaluation based on functional analysis of nursing procedures. 10 beds in a medical intensive care unit (MICU). Patients admitted from November 15, 1995, to June 15, 1996, were included and divided in two groups based on presence of MRB colonization or infection (MRB+ and MRB-groups). Data were collected regarding length of stay (LOS) in days; Omega score for the entire stay; PRN score for the entire stay and per day; and time required to perform correctly four nursing procedures related to MRB NI, as evaluated specifically by the nursing staff, using a detailed functional analysis document that described all elementary nursing tasks in chronological order and all material needed to carry out those tasks. The LOS and total Omega and PRN scores were higher in the MRB+ group than in the MRB- group: LOS, 23 +/- 20.6 versus 12 +/- 15.3 days, (Pmanagement; and microbiological screening. The functional analysis indicated that the time needed to carry out these four procedures correctly was 245 minutes per patient per day, as compared to 85 minutes according to the PRN system. Our data confirm that MRB NIs are responsible for an increase in nurse work load, as estimated by LOS, Omega, and PRN scores. However, the daily excess nurse work load related directly to recommended procedures for managing MRB NIs in MICUs is underestimated by these activity scores, as compared to a specific functional analysis of nursing tasks. This may be of importance in evaluating potential links between nurse work load and MRB NIs and in determining the number of nurse hours needed to comply with infection control recommendations.

  7. Antibiotic modulation of capsular exopolysaccharide and virulence in Acinetobacter baumannii.

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    Edward Geisinger

    2015-02-01

    Full Text Available Acinetobacter baumannii is an opportunistic pathogen of increasing importance due to its propensity for intractable multidrug-resistant infections in hospitals. All clinical isolates examined contain a conserved gene cluster, the K locus, which determines the production of complex polysaccharides, including an exopolysaccharide capsule known to protect against killing by host serum and to increase virulence in animal models of infection. Whether the polysaccharides determined by the K locus contribute to intrinsic defenses against antibiotics is unknown. We demonstrate here that mutants deficient in the exopolysaccharide capsule have lowered intrinsic resistance to peptide antibiotics, while a mutation affecting sugar precursors involved in both capsule and lipopolysaccharide synthesis sensitizes the bacterium to multiple antibiotic classes. We observed that, when grown in the presence of certain antibiotics below their MIC, including the translation inhibitors chloramphenicol and erythromycin, A. baumannii increases production of the K locus exopolysaccharide. Hyperproduction of capsular exopolysaccharide is reversible and non-mutational, and occurs concomitantly with increased resistance to the inducing antibiotic that is independent of the presence of the K locus. Strikingly, antibiotic-enhanced capsular exopolysaccharide production confers increased resistance to killing by host complement and increases virulence in a mouse model of systemic infection. Finally, we show that augmented capsule production upon antibiotic exposure is facilitated by transcriptional increases in K locus gene expression that are dependent on a two-component regulatory system, bfmRS. These studies reveal that the synthesis of capsule, a major pathogenicity determinant, is regulated in response to antibiotic stress. Our data are consistent with a model in which gene expression changes triggered by ineffectual antibiotic treatment cause A. baumannii to transition

  8. Acinetobacter baumannii invades epithelial cells and outer membrane protein A mediates interactions with epithelial cells

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    Park Tae

    2008-12-01

    Full Text Available Abstract Background Acinetobacter baumannii is a nosocomial pathogen of increasing importance, but the pathogenic mechanism of this microorganism has not been fully explored. This study investigated the potential of A. baumannii to invade epithelial cells and determined the role of A. baumannii outer membrane protein A (AbOmpA in interactions with epithelial cells. Results A. baumannii invaded epithelial cells by a zipper-like mechanism, which is associated with microfilament- and microtubule-dependent uptake mechanisms. Internalized bacteria were located in the membrane-bound vacuoles. Pretreatment of recombinant AbOmpA significantly inhibited the adherence to and invasion of A. baumannii in epithelial cells. Cell invasion of isogenic AbOmpA- mutant significantly decreased as compared with wild-type bacteria. In a murine pneumonia model, wild-type bacteria exhibited a severe lung pathology and induced a high bacterial burden in blood, whereas AbOmpA- mutant was rarely detected in blood. Conclusion A. baumannii adheres to and invades epithelial cells. AbOmpA plays a major role in the interactions with epithelial cells. These findings contribute to the understanding of A. baumannii pathogenesis in the early stage of bacterial infection.

  9. Prevalence and resistance of Acinetobacter baumannii isolated at Hyatabad Medical Complex, Khyber Pakhtunkhwa, Pakistan

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    Said Hassan

    2016-09-01

    Full Text Available Objective: To assess the resistance against widely used antibiotics in case of Acinetobacter baumannii (A. baumannii infection. Methods: A total of 350 samples of pus, urine, swab and others from different patients were examined and the bacterial growth appeared in 50 samples. Each sample was inoculated on blood, MacConkey and cystine lactose electrolyte deficient agar. The antimicrobial susceptibility profile of the isolates was determined using agar plate method/disk-diffusion method (modified-Kirby Baur disc diffusion method. Results: In current study, a large number of isolates of A. baumannii obtained from different specimens were resistant to avelox (56%, followed by tygacil (46%, augmentin (46%, cefspan (38%, cefixime (24% and ampicillin (20%. However, the antibiogram of A. baumannii also showed that most of the isolates (88% were highly sensitive to cefalexin. Second maximum sensitivity of A. baumannii was seen to amikacin (84%. The sensitivity of isolates against amikacin was followed by ticarcillin (80%. Meronem was found highly active against the tested isolates (78%. Sensitivity was observed for tienem (76%, sulzone (72% followed by azactam (68%, cefobid (66% to cefotaxime (66% and ciproxin (62%. Conclusions: Results elucidate that A. baumannii is a severe problem as it has become a highly resistant species in hospitalized patients and resistant A. baumannii infection turned out to have increased all-cause mortality.

  10. Molecular detection of aminoglycoside-modifying enzyme genes in Acinetobacter baumannii clinical isolates.

    Science.gov (United States)

    Heidary, Mohsen; Salimi Chirani, Alireza; Khoshnood, Saeed; Eslami, Gita; Atyabi, Seyyed Mohammad; Nazem, Habibollah; Fazilati, Mohammad; Hashemi, Ali; Soleimani, Saleh

    2017-06-01

    Acinetobacter baumannii is a major opportunistic pathogen in healthcare settings worldwide. In Iran, there are only few reports on the prevalence of aminoglycoside resistance genes among A. baumannii isolates. The aim of this study was to investigate the existence of aminoglycoside-modifying enzyme (AME) genes from A. baumannii strains collected at a university teaching hospital in Iran. One hundred A. baumannii strains were collected between 2014 and 2015 from hospitalized patients at Loghman Hakim Hospital, Tehran, Iran. Antimicrobial susceptibility was determined by disk diffusion method according to the Clinical and Laboratory Standards Institute recommendations. The DNA was extracted using a kit obtained from Bioneer Co. (Korea) and was used as a template for polymerase chain reaction. The most active antimicrobial agent against these strains was colistin. The rate of extended-spectrum cephalosporin resistance was 97%. The aadA1, aadB, aac(6')-Ib, and aac(3)-IIa genes were found in 85%, 77%, 72%, and 68% of A. baumannii isolates, respectively. This study showed a high prevalence rate of AME genes in A. baumannii. This prevalence rate has explained that further aminoglycoside resistance genes may have role in the resistance of clinical isolates of A. baumannii. Therefore, control and treatment of serious infections caused by this opportunistic pathogen should be given more consideration.

  11. Isolation and characterization of antimicrobial compounds in plant extracts against multidrug-resistant Acinetobacter baumannii.

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    Yoko Miyasaki

    Full Text Available The number of fully active antibiotic options that treat nosocomial infections due to multidrug-resistant Acinetobacter baumannii (A. baumannii is extremely limited. Magnolia officinalis, Mahonia bealei, Rabdosia rubescens, Rosa rugosa, Rubus chingii, Scutellaria baicalensis, and Terminalia chebula plant extracts were previously shown to have growth inhibitory activity against a multidrug-resistant clinical strain of A. baumannii. In this study, the compounds responsible for their antimicrobial activity were identified by fractionating each plant extract using high performance liquid chromatography, and determining the antimicrobial activity of each fraction against A. baumannii. The chemical structures of the fractions inhibiting >40% of the bacterial growth were elucidated by liquid chromatography/mass spectrometry analysis and nuclear magnetic resonance spectroscopy. The six most active compounds were identified as: ellagic acid in Rosa rugosa; norwogonin in Scutellaria baicalensis; and chebulagic acid, chebulinic acid, corilagin, and terchebulin in Terminalia chebula. The most potent compound was identified as norwogonin with a minimum inhibitory concentration of 128 µg/mL, and minimum bactericidal concentration of 256 µg/mL against clinically relevant strains of A. baumannii. Combination studies of norwogonin with ten anti-Gram negative bacterial agents demonstrated that norwogonin did not enhance the antimicrobial activity of the synthetic antibiotics chosen for this study. In conclusion, of all identified antimicrobial compounds, norwogonin was the most potent against multidrug-resistant A. baumannii strains. Further studies are warranted to ascertain the prophylactic and therapeutic potential of norwogonin for infections due to multidrug-resistant A. baumannii.

  12. Synergistic effects of ethnomedicinal plants of Apocynaceae family and antibiotics against clinical isolates of Acinetobacter baumannii.

    Science.gov (United States)

    Chusri, Sasitorn; Siriyong, Thanyaluck; Na-Phatthalung, Pinanong; Voravuthikunchai, Supayang Piyawan

    2014-06-01

    To investigate the efficacy of 17 ethnomedicinal plants belonging to Apocynaceae family used in combination with 16 conventional antibiotics against non-multidrug resistant-, multidrug resistant (MDR)-, and extensive drug resistant (XDR) Acinetobacter baumannii (A. baumannii). Antibacterial activity and resistance modifying ability of 272 combinations were determined by growth inhibition assays and further confirmed by time-kill assay. Among the combinations of the antibiotics with Apocynaceae ethanol extracts on this pathogen, 15 (5%) had synergistic effects, 23 (8%) had partial synergistic effects and 234 (86%) had no effects. Synergistic activity was observed mostly when the Apocynaceae extracts were combined with rifampicin or cefazolin. Interestingly, 10 out of 17 combinations between the extracts and rifampicin displayed synergistic or partial synergistic behaviors. Holarrhena antidysenterica extract was additionally tested to restore rifampicin activity against clinical isolates of MDR and XDR A. baumannii. With respect to total or partial synergy, 70% was XDR A. baumannii isolates and 66% was MDR A. baumannii isolates. Holarrhena antidysenterica extract clearly demonstrated the ability to restore rifampicin activity against both A. baumannii ATCC19606 and clinically isolated A. baumannii. Additional studies examining its active principles as well as mechanisms of actions such as the effects on efflux pumps and outer membrane permeability alterations are recommended. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  13. Role of macrophages in early host resistance to respiratory Acinetobacter baumannii infection.

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    Hongyu Qiu

    Full Text Available Acinetobacter baumannii is an emerging bacterial pathogen that causes nosocomial pneumonia and other infections. Although it is recognized as an increasing threat to immunocompromised patients, the mechanism of host defense against A. baumannii infection remains poorly understood. In this study, we examined the potential role of macrophages in host defense against A. baumannii infection using in vitro macrophage culture and the mouse model of intranasal (i.n. infection. Large numbers of A. baumannii were taken up by alveolar macrophages in vivo as early as 4 h after i.n. inoculation. By 24 h, the infection induced significant recruitment and activation (enhanced expression of CD80, CD86 and MHC-II of macrophages into bronchoalveolar spaces. In vitro cell culture studies showed that A. baumannii were phagocytosed by J774A.1 (J774 macrophage-like cells within 10 minutes of co-incubation, and this uptake was microfilament- and microtubule-dependent. Moreover, the viability of phagocytosed bacteria dropped significantly between 24 and 48 h after co-incubation. Infection of J774 cells by A. baumannii resulted in the production of large amounts of proinflammatory cytokines and chemokines, and moderate amounts of nitric oxide (NO. Prior treatment of J774 cells with NO inhibitors significantly suppressed their bactericidal efficacy (P<0.05. Most importantly, in vivo depletion of alveolar macrophages significantly enhanced the susceptibility of mice to i.n. A. baumannii challenge (P<0.01. These results indicate that macrophages may play an important role in early host defense against A. baumannii infection through the efficient phagocytosis and killing of A. baumannii to limit initial pathogen replication and the secretion of proinflammatory cytokines and chemokines for the rapid recruitment of other innate immune cells such as neutrophils.

  14. Pathogenic Bacterium Acinetobacter baumannii Inhibits the Formation of Neutrophil Extracellular Traps by Suppressing Neutrophil Adhesion

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    Go Kamoshida

    2018-02-01

    Full Text Available Hospital-acquired infections caused by Acinetobacter baumannii have become problematic because of high rates of drug resistance. A. baumannii is usually harmless, but it may cause infectious diseases in an immunocompromised host. Although neutrophils are the key players of the initial immune response against bacterial infection, their interactions with A. baumannii remain largely unknown. A new biological defense mechanism, termed neutrophil extracellular traps (NETs, has been attracting attention. NETs play a critical role in bacterial killing by bacterial trapping and inactivation. Many pathogenic bacteria have been reported to induce NET formation, while an inhibitory effect on NET formation is rarely reported. In the present study, to assess the inhibition of NET formation by A. baumannii, bacteria and human neutrophils were cocultured in the presence of phorbol 12-myristate 13-acetate (PMA, and NET formation was evaluated. NETs were rarely observed during the coculture despite neutrophil PMA stimulation. Furthermore, A. baumannii prolonged the lifespan of neutrophils by inhibiting NET formation. The inhibition of NET formation by other bacteria was also investigated. The inhibitory effect was only apparent with live A. baumannii cells. Finally, to elucidate the mechanism of this inhibition, neutrophil adhesion was examined. A. baumannii suppressed the adhesion ability of neutrophils, thereby inhibiting PMA-induced NET formation. This suppression of cell adhesion was partly due to suppression of the surface expression of CD11a in neutrophils. The current study constitutes the first report on the inhibition of NET formation by a pathogenic bacterium, A. baumannii, and prolonging the neutrophil lifespan. This novel pathogenicity to inhibit NET formation, thereby escaping host immune responses might contribute to a development of new treatment strategies for A. baumannii infections.

  15. Pathogenic Bacterium Acinetobacter baumannii Inhibits the Formation of Neutrophil Extracellular Traps by Suppressing Neutrophil Adhesion

    Science.gov (United States)

    Kamoshida, Go; Kikuchi-Ueda, Takane; Nishida, Satoshi; Tansho-Nagakawa, Shigeru; Ubagai, Tsuneyuki; Ono, Yasuo

    2018-01-01

    Hospital-acquired infections caused by Acinetobacter baumannii have become problematic because of high rates of drug resistance. A. baumannii is usually harmless, but it may cause infectious diseases in an immunocompromised host. Although neutrophils are the key players of the initial immune response against bacterial infection, their interactions with A. baumannii remain largely unknown. A new biological defense mechanism, termed neutrophil extracellular traps (NETs), has been attracting attention. NETs play a critical role in bacterial killing by bacterial trapping and inactivation. Many pathogenic bacteria have been reported to induce NET formation, while an inhibitory effect on NET formation is rarely reported. In the present study, to assess the inhibition of NET formation by A. baumannii, bacteria and human neutrophils were cocultured in the presence of phorbol 12-myristate 13-acetate (PMA), and NET formation was evaluated. NETs were rarely observed during the coculture despite neutrophil PMA stimulation. Furthermore, A. baumannii prolonged the lifespan of neutrophils by inhibiting NET formation. The inhibition of NET formation by other bacteria was also investigated. The inhibitory effect was only apparent with live A. baumannii cells. Finally, to elucidate the mechanism of this inhibition, neutrophil adhesion was examined. A. baumannii suppressed the adhesion ability of neutrophils, thereby inhibiting PMA-induced NET formation. This suppression of cell adhesion was partly due to suppression of the surface expression of CD11a in neutrophils. The current study constitutes the first report on the inhibition of NET formation by a pathogenic bacterium, A. baumannii, and prolonging the neutrophil lifespan. This novel pathogenicity to inhibit NET formation, thereby escaping host immune responses might contribute to a development of new treatment strategies for A. baumannii infections. PMID:29467765

  16. Emergence of multiresistant methicillin-resistant Staphylococcus aureus in two patients with atopic dermatitis requiring linezolid treatment.

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    Rosa, Jaime S; Ross, Lawrence A; Ong, Peck Y

    2014-01-01

    We report two patients with atopic dermatitis who developed methicillin-resistant Staphylococcus aureus (MRSA) skin infections resistant to clindamycin and trimethoprim-sulfamethoxazole requiring repeated linezolid treatment. For one patient and family members who received an aggressive regimen of staphylococcal decolonization, including intranasal mupirocin, dilute bleach baths, and bleach cleansing of household items and surfaces, subsequent culture results demonstrated methicillin-susceptible S. aureus colonization and infection. These findings underscore the challenges presented by multiresistant MRSA infections in children with atopic dermatitis. © 2012 Wiley Periodicals, Inc.

  17. Molecular epidemiology and spatiotemporal analysis of hospital-acquired Acinetobacter baumannii infection in a tertiary care hospital in southern Thailand.

    Science.gov (United States)

    Chusri, S; Chongsuvivatwong, V; Rivera, J I; Silpapojakul, K; Singkhamanan, K; McNeil, E; Doi, Y

    2017-01-01

    Acinetobacter baumannii is a major hospital-acquired pathogen in Thailand that has a negative effect on patient survival. The nature of its transmission is poorly understood. To investigate the genotypic and spatiotemporal pattern of A. baumannii infection at a hospital in Thailand. The medical records of patients infected with A. baumannii at an 800-bed tertiary care hospital in southern Thailand between January 2010 and December 2011 were reviewed retrospectively. A. baumannii was identified at the genomospecies level. Carbapenemase genes were identified among carbapenem-resistant isolates associated with A. baumannii infection. A spatiotemporal analysis was performed by admission ward, time of infection and pulsed-field gel electrophoresis (PFGE) groups of A. baumannii. Nine PFGE groups were identified among the 197 A. baumannii infections. All A. baumannii isolates were assigned to International Clonal Lineage II. bla OXA-23 was the most prevalent carbapenemase gene. Outbreaks were observed mainly in respiratory and intensive care units. The association between PFGE group and hospital unit was significant. Spatiotemporal analysis identified 20 clusters of single PFGE group infections. Approximately half of the clusters involved multiple hospital units simultaneously. A. baumannii transmitted both within and between hospital wards. Better understanding and control of the transmission of A. baumannii are needed. Copyright © 2016 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  18. Genetic Regulation of Virulence and Antibiotic Resistance in Acinetobacter baumannii

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    Carsten Kröger

    2016-12-01

    Full Text Available Multidrug resistant microorganisms are forecast to become the single biggest challenge to medical care in the 21st century. Over the last decades, members of the genus Acinetobacter have emerged as bacterial opportunistic pathogens, in particular as challenging nosocomial pathogens because of the rapid evolution of antimicrobial resistances. Although we lack fundamental biological insight into virulence mechanisms, an increasing number of researchers are working to identify virulence factors and to study antibiotic resistance. Here, we review current knowledge regarding the regulation of virulence genes and antibiotic resistance in Acinetobacter baumannii. A survey of the two-component systems AdeRS, BaeSR, GacSA and PmrAB explains how each contributes to antibiotic resistance and virulence gene expression, while BfmRS regulates cell envelope structures important for pathogen persistence. A. baumannii uses the transcription factors Fur and Zur to sense iron or zinc depletion and upregulate genes for metal scavenging as a critical survival tool in an animal host. Quorum sensing, nucleoid-associated proteins, and non-classical transcription factors such as AtfA and small regulatory RNAs are discussed in the context of virulence and antibiotic resistance.

  19. Genetic Regulation of Virulence and Antibiotic Resistance in Acinetobacter baumannii

    Science.gov (United States)

    Kröger, Carsten; Kary, Stefani C.; Schauer, Kristina; Cameron, Andrew D. S.

    2016-01-01

    Multidrug resistant microorganisms are forecast to become the single biggest challenge to medical care in the 21st century. Over the last decades, members of the genus Acinetobacter have emerged as bacterial opportunistic pathogens, in particular as challenging nosocomial pathogens because of the rapid evolution of antimicrobial resistances. Although we lack fundamental biological insight into virulence mechanisms, an increasing number of researchers are working to identify virulence factors and to study antibiotic resistance. Here, we review current knowledge regarding the regulation of virulence genes and antibiotic resistance in Acinetobacter baumannii. A survey of the two-component systems AdeRS, BaeSR, GacSA and PmrAB explains how each contributes to antibiotic resistance and virulence gene expression, while BfmRS regulates cell envelope structures important for pathogen persistence. A. baumannii uses the transcription factors Fur and Zur to sense iron or zinc depletion and upregulate genes for metal scavenging as a critical survival tool in an animal host. Quorum sensing, nucleoid-associated proteins, and non-classical transcription factors such as AtfA and small regulatory RNAs are discussed in the context of virulence and antibiotic resistance. PMID:28036056

  20. What Expands in an Expanding Universe?

    Directory of Open Access Journals (Sweden)

    JOSÉ A. DE FREITAS PACHECO

    2015-12-01

    Full Text Available ABSTRACT In the present investigation, the possible effects of the expansion of the Universe on systems bonded either by gravitational or electromagnetic forces, are reconsidered. It will be shown that the acceleration (positive or negative of the expanding background, is the determinant factor affecting planetary orbits and atomic sizes. In the presently accepted cosmology (ΛCDM all bonded systems are expanding at a decreasing rate that tends to be zero as the universe enters in a de Sitter phase. It is worth mentioning that the estimated expansion rates are rather small and they can be neglected for all practical purposes.

  1. What Expands in an Expanding Universe?

    Science.gov (United States)

    Pacheco, José A De Freitas

    2015-01-01

    In the present investigation, the possible effects of the expansion of the Universe on systems bonded either by gravitational or electromagnetic forces, are reconsidered. It will be shown that the acceleration (positive or negative) of the expanding background, is the determinant factor affecting planetary orbits and atomic sizes. In the presently accepted cosmology (ΛCDM) all bonded systems are expanding at a decreasing rate that tends to be zero as the universe enters in a de Sitter phase. It is worth mentioning that the estimated expansion rates are rather small and they can be neglected for all practical purposes.

  2. Mortalidad por Acinetobacter baumannii en unidades de cuidados intensivos en Colombia Acinetobacter baumannii - related mortality in intensive care units in Colombia

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    Elkin V Lemos

    2011-10-01

    Full Text Available OBJETIVO: Comparar la mortalidad en pacientes infectados por Acinetobacter baumannii multisensibles con pacientes infectados por A. baumannii multirresistentes hospitalizados en unidades de cuidados intensivos (UCI de Colombia. MÉTODOS: Estudio prospectivo, observacional y multicéntrico. Se incluyó a 165 pacientes ingresados en las UCIs participantes entre abril de 2006 y abril de 2010. Se comparó la mortalidad de los pacientes con aislamientos clínicos de A. baumannii multirresistentes frente a aquellos multisensibles al día 14 y 30 de hospitalización. RESULTADOS: De los 165 pacientes adultos que presentaron infecciones asociadas al cuidado en salud (IACS por A. baumannii, en 62 se encontraron bacterias multisensibles y en 103, multirresistentes. No se hallaron diferencias estadísticamente significativas en la mortalidad al día 14 de hospitalización en UCI. Sí se observaron en cambio diferencias significativas (P OBJECTIVE: Compare mortality in multidrug-susceptible Acinetobacter baumannii infected patients and multidrug-resistant A. baumannii-infected patients hospitalized in intensive care units (ICUs in Colombia. METHODS: A prospective, observational, and multicenter study. A total of 165 patients admitted to the participating ICUs from April 2006 to April 2010 were included. On day 14 and day 30 of hospitalization, mortality in multidrug-resistant patients with clinical isolates of A. baumannii was compared with that in multidrug-susceptible patients. RESULTS: Of the 165 adult patients who had health care-associated infections (HAI caused by A. baumannii, multidrug-susceptible bacteria were found in 62 patients and multidrug-resistant bacteria in 103. Statistically significant differences in mortality on day 14 of hospitalization in the ICU were not found. On the other hand, significant differences (P < 0.05 in mortality on day 30 of hospitalization were observed between patients with multidrug-resistant isolates and those with

  3. Laboratory evaluation of the ESwab transport system for the recovery of carbapenem-resistant Acinetobacter baumannii.

    Science.gov (United States)

    Moran-Gilad, J; Schwartz, D; Navon-Venezia, S; Carmeli, Y

    2012-07-01

    Microbiological surveillance for detection of carbapenem-resistant A. baumannii is important, but recovery of A. baumannii is inadequate. We studied A. baumannii recovery by a particular transport system that is possibly superior over standard swabs, using reference and clinical strains. First, the recovery rates relating to the various swabs were compared with regard to various combinations of transport times (0 h, 1 h, 24 h, 48 h), storage times (0 weeks, 1 week, 2 weeks, 4 weeks) and storage temperatures (4°c,-80°c) using live counts. Second, the recovery of different inocula of strains mixed with fecal microbiota was evaluated by plating on selective medium. The new transport system exhibited a decline of system performed well, even after prolonged transport or with a low inoculum, and its processing could be delayed by up to 2 weeks, especially if refrigerated. The new transport system may thus enhance A. baumannii surveillance.

  4. Pan Drug-Resistant Environmental Isolate of Acinetobacter baumannii from Croatia.

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    Goic-Barisic, Ivana; Seruga Music, Martina; Kovacic, Ana; Tonkic, Marija; Hrenovic, Jasna

    2017-06-01

    Acinetobacter baumannii is an emerging nosocomial pathogen with also emerging resistance to different antibiotics. Multidrug and pan drug-resistant clinical isolates were reported worldwide. Here we report the first evidence of pan drug-resistant environmental isolate of A. baumannii. The isolate was recovered from the effluent of secondary treated municipal wastewater of the City of Zagreb, Croatia. The isolate was resistant to penicillins/β-lactamase inhibitors, carbapenems, fluoroquinolones, aminoglycosides, folate pathway inhibitors, and polymyxins, except intermediately susceptible to minocycline and tigecycline. Intrinsic chromosomally located bla OXA-51-like gene and acquired plasmid-located bla OXA-23-like gene were related to clinical isolates. Pan drug-resistant A. baumannii can occur in natural environments outside of the hospital. Secondary treated municipal wastewater represents a potential epidemiological reservoir of pan drug-resistant A. baumannii and carbapenem resistance gene.

  5. Host-microbe interactions that shape the pathogenesis of Acinetobacter baumannii infection

    Science.gov (United States)

    Mortensen, Brittany L.; Skaar, Eric P.

    2013-01-01

    Summary Acinetobacter baumannii is an opportunistic pathogen that has emerged as a prevalent source of nosocomial infections, most frequently causing ventilator-associated pneumonia. The emergence of pan-drug resistant strains magnifies the problem by reducing viable treatment options and effectively increasing the mortality rate associated with Acinetobacter infections. In light of this rising threat, research on A. baumannii epidemiology, antibiotic resistance, and pathogenesis is accelerating. The recent development of both in vitro and in vivo models has enabled studies probing the host-Acinetobacter interface. Bacterial genetic screens and comparative genomic studies have led to the identification of several A. baumannii virulence factors. Additionally, investigations into host defense mechanisms using animal models or cell culture have provided insight into the innate immune response to infection. This review highlights some of the key attributes of A. baumannii virulence with an emphasis on bacterial interactions with the innate immune system. PMID:22640368

  6. Molecular identification of Acinetobacter baumannii isolated from intensive care units and their antimicrobial resistance patterns

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    Hasan Ghajavand

    2015-01-01

    Conclusion: This study showed a high resistance of A. baumannii to a wide range of antimicrobial agent. It is necessary to adopt appropriate strategies to control the spread of the bacteria in care unit centers and wards.

  7. Biofilm formation in clinical isolates of nosocomial Acinetobacter baumannii and its relationship with multidrug resistance

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    Ebrahim Babapour

    2016-06-01

    Conclusions: Since most of the multidrug resistant strains produce biofilm, it seems necessary to provide continuous monitoring and determination of antibiotic susceptibility of clinical A. baumannii. This would help to select the most appropriate antibiotic for treatment.

  8. Repeated local emergence of carbapenem-resistant Acinetobacter baumannii in a single hospital ward

    OpenAIRE

    Schultz, Mark B.; Pham Thanh, Duy; Tran Do Hoan, Nhu; Wick, Ryan R.; Ingle, Danielle J.; Hawkey, Jane; Edwards, David J.; Kenyon, Johanna J.; Phu Huong Lan, Nguyen; Campbell, James I.; Thwaites, Guy; Thi Khanh Nhu, Nguyen; Hall, Ruth M.; Fournier-Level, Alexandre; Baker, Stephen

    2016-01-01

    We recently reported a dramatic increase in the prevalence of carbapenem-resistant Acinetobacter baumannii infections in the intensive care unit (ICU) of a Vietnamese hospital. This upsurge was associated with a specific oxa23-positive clone that was identified by multilocus VNTR analysis. Here, we used whole-genome sequence analysis to dissect the emergence of carbapenem-resistant A. baumannii causing ventilator-associated pneumonia (VAP) in the ICU during 2009?2012. To provide historical co...

  9. Blood stream infections caused by Acinetobacter baumannii group in Japan - Epidemiological and clinical investigation.

    Science.gov (United States)

    Fujikura, Yuji; Yuki, Atsushi; Hamamoto, Takaaki; Kawana, Akihiko; Ohkusu, Kiyofumi; Matsumoto, Tetsuya

    2016-06-01

    Acinetobacter calcoaceticus-Acinetobacter baumannii complex, especially A. baumannii, Acinetobacter pittii and Acinetobacter nosocomialis, constitutes an important group of nosocomial pathogens; however, epidemiological or clinical characteristics and prognosis is limited in Japan. From 2009 to 2013, 47 blood stream infection cases resulting from A. baumannii group were reviewed at the National Defense Medical College, an 800-bed tertiary hospital. To determine the genospecies, further comparative nucleotide sequence analyses of the RNA polymerase b-subunit (rpoB) gene were performed. Sequence analysis of rpoB gene showed that 25 (49.0%), 17 (33.3%) and 5 (9.8%) cases were caused by A. baumannii, A. pittii and A. nosocomialis, respectively. The 30-day and in-hospital mortality rates of A. baumannii were 8.5% and 25.5%, respectively, and there were no significant differences between Acinetobacter species. Clinical characteristics were statistically insignificant. Multidrug-resistant Acinetobacter species were detected in 3 cases (5.9%) with same pulsed-field gel electrophoresis (PFGE) pattern and A. baumannii was less susceptible to amikacin and levofloxacin. In this study, the mortality and clinical characteristics were similar among A. baumannii group isolate cases despite some showing drug resistance. However, identification of Acinetobacter species helps to initiate appropriate antibiotic therapy in earlier treatment phase, because A. baumannii shows some drug resistance. Copyright © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  10. Rapid dissemination of colistin and carbapenem resistant Acinetobacter baumannii in Central Greece: mechanisms of resistance, molecular identification and epidemiological data

    OpenAIRE

    Oikonomou, O.; Sarrou, S.; Papagiannitsis, C. C.; Georgiadou, S.; Mantzarlis, K.; Zakynthinos, E.; Dalekos, G. N.; Petinaki, E.

    2015-01-01

    Background Colistin-resistant/carbapenem-resistant Acinetobacter baumannii is a significant challenge for antibiotic treatment and infection control policies. Since 2012, in Central Greece an increase of colistin/pan- resistant A. baumannii has occurred, indicating the need for further analysis. Methods A total of 86 colistin-resistant/carbapenem-resistant out of 1228 A. baumannii clinical isolates, consecutively collected between 2012 and 2014 in a tertiary Greek hospital of Central Greece, ...

  11. In Vitro Synergistic Activity of Antimicrobial Agents in Combination against Clinical Isolates of Colistin-Resistant Acinetobacter baumannii

    OpenAIRE

    Bae, Seongman; Kim, Min-Chul; Park, Su-Jin; Kim, Hee Sueng; Sung, Heungsup; Kim, Mi-Na; Kim, Sung-Han; Lee, Sang-Oh; Choi, Sang-Ho; Woo, Jun Hee; Kim, Yang Soo; Chong, Yong Pil

    2016-01-01

    Emerging resistance to colistin in clinical Acinetobacter baumannii isolates is of growing concern. Since current treatment options for these strains are extremely limited, we investigated the in vitro activities of various antimicrobial combinations against colistin-resistant A. baumannii. Nine clinical isolates (8 from bacteremia cases and 1 from a pneumonia case) of colistin-resistant A. baumannii were collected in Asan Medical Center, Seoul, South Korea, between January 2010 and December ...

  12. Antibacterial activity of Hibiscus sabdariffa L. calyces against hospital isolates of multidrug resistant Acinetobacter baumannii

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    Emad Mohamed Abdallah

    2016-11-01

    Full Text Available Objective: To evaluate the antibacterial activity of methanol extract of Hibiscus sabdariffa (H. sabdariffa calyces employed in Sudanese folk medicine against five hospital isolates of multidrug resistant Acinetobacter baumannii (MDR A. baumannii. Methods: The antibacterial activity of 80% methanol extract (v/v of H. sabdariffa calyces was evaluated by agar disc diffusion, minimum inhibitory concentration and minimum bactericidal concentration methods. Antibiotic susceptibility of selected A. baumannii strains was tested. Results: In the present investigation, the methanol extract from the calyces of H. sabdariffa exhibited significant antibacterial properties against the non-MDR A. baumannii as well as the MDR A. baumannii strains with a zone of inhibition ranging from (11.3 ± 0.3 to (13.6 ± 0.3 mm. The relative percentage inhibition of H. sabdariffa extract (10 mg/disc with respect to gentamicin (10 mg/disc had potent antibacterial properties and was much more effective than gentamicin. Values of minimum inhibitory concentration and minimum bactericidal concentration ranged from 25 to 50 and 50 to 100 mg/mL, respectively, revealing the potential bactericidal properties of the extract. Conclusions: According to the present study, the calyces of H. sabdariffa can be used as a substitute source of the current ineffective synthetic antibiotics used against MDR A. baumannii.

  13. Economic value of Acinetobacter baumannii screening in the intensive care unit.

    Science.gov (United States)

    Lee, B Y; McGlone, S M; Doi, Y; Bailey, R R; Harrison, L H

    2011-11-01

    Although Acinetobacter baumannii (A. baumannii) is an increasingly common nosocomial pathogen that can cause serious infections in the intensive care unit (ICU), most ICUs do not actively screen admissions for this pathogen. We developed an economic computer simulation model to determine the potential cost-consequences to the hospital of implementing routine A. baumannii screening of ICU admissions and isolating those patients who tested positive, comparing two screening methods, sponge and swab, with each other and no screening. Sensitivity analyses varied the colonization prevalence, percentage of colonized individuals who had active A. baumannii infections, A. baumannii reproductive rate (R), and contact isolation efficacy. Both screening methods were cost-effective for almost all scenarios tested, yielding cost-savings ranging from -$1 to -$1563. Sponge screening was not cost-saving when colonization prevalence was ≤1%, probability of infection ≤30%, R ≤ 0.25, and contact isolation efficacy ≤25%. Swab screening was not cost-saving under these same conditions when the probability of infection was ≤40%. Sponge screening tended to be more cost-saving than swab screening (additional savings ranged from $1 to $421). Routine A. baumannii screening of ICU patients may save costs for hospitals. © 2011 The Authors. Clinical Microbiology and Infection © 2011 European Society of Clinical Microbiology and Infectious Diseases.

  14. Characterization of colistin-resistant A. baumannii isolated in Intensive Care Unit of an Italian Hospital

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    Erika Coppo

    2013-03-01

    Full Text Available We report the characterization of an Acinetobacter baumannii resistant to colistin isolated from a patient treated with colistin for 22 days. The identification and initial susceptibility testing of the strain was performed at ASL3 Imperiese with the Vitek-2 automated system and than the strain was re-identified at the Sezione di Microbiologia with APINE. In vitro activity of antimicrobial agents was determined by the microdiluition methods. The detection of the beta-lactamase gene was performed by PCR and for the analysis of LPS were sequenced the genes of the PmrABC system. We compared the PFGE profile of the colistin-resistant A. baumannii with 5 A. baumannii colistin-susceptible strains isolated in the same Hospital during 2010. The strain was resistant to all antimicrobial agents tested, except to tygecyclin. The PFGE shown that the A. baumannii colistin-resistant was closery related to the colistin-susceptible strains. The sequencing of the PmrABC system showed that the strain had a single mutation in the PmrB component. Colistin-resistant strain have recently been found in several Gram-negative bacteria such A. baumannii, K. pneumoniae and P. aeruginosa. This clinical case confirms that resistance to colistin in A. baumannii can be selected in vivo following the use of colistin in therapy.

  15. Genomic sequencing of a strain of Acinetobacter baumannii and potential mechanisms to antibiotics resistance.

    Science.gov (United States)

    Zhao, Lei; Li, Hongru; Zhu, Ziwen; Wakefield, Mark R; Fang, Yujiang; Ye, Ying

    2017-06-01

    Acinetobacter baumannii has been becoming a great challenge to clinicians due to their resistance to almost all available antibiotics. In this study, we sequenced the genome from a multiple antibiotics resistant Acinetobacter baumannii stain which was named A. baumannii-1isolated from China by SMRT sequencing technology to explore its potential mechanisms to antibiotic resistance. We found that several mechanisms might contribute to the antibiotic resistance of Acinetobacter baumannii. Specifically, we found that SNP in genes associated with nucleotide excision repair and ABC transporter might contribute to its resistance to multiple antibiotics; we also found that specific genes associated with bacterial DNA integration and recombination, DNA-mediated transposition and response to antibiotics might contribute to its resistance to multiple antibiotics; Furthermore, specific genes associated with penicillin and cephalosporin biosynthetic pathway and specific genes associated with CHDL and MBL β-lactamase genes might contribute to its resistance to multiple antibiotics. Thus, the detailed mechanisms by which Acinetobacter baumannii show extensive resistance to multiple antibiotics are very complicated. Such a study might be helpful to develop new strategies to control Acinetobacter baumannii infection. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Carbapenem resistance in Pseudomonas aeruginosa and Acinetobacter baumannii in the nosocomial setting in Latin America.

    Science.gov (United States)

    Labarca, Jaime A; Salles, Mauro José Costa; Seas, Carlos; Guzmán-Blanco, Manuel

    2016-01-01

    Increasing prevalence of carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii strains in the nosocomial setting in Latin America represents an emerging challenge to public health, as the range of therapeutic agents active against these pathogens becomes increasingly constrained. We review published reports from 2002 to 2013, compiling data from throughout the region on prevalence, mechanisms of resistance and molecular epidemiology of carbapenem-resistant strains of P. aeruginosa and A. baumannii. We find rates of carbapenem resistance up to 66% for P. aeruginosa and as high as 90% for A. baumannii isolates across the different countries of Latin America, with the resistance rate of A. baumannii isolates greater than 50% in many countries. An outbreak of the SPM-1 carbapenemase is a chief cause of resistance in P. aeruginosa strains in Brazil. Elsewhere in Latin America, members of the VIM family are the most important carbapenemases among P. aeruginosa strains. Carbapenem resistance in A. baumannii in Latin America is predominantly due to the oxacillinases OXA-23, OXA-58 and (in Brazil) OXA-143. Susceptibility of P. aeruginosa and A. baumannii to colistin remains high, however, development of resistance has already been detected in some countries. Better epidemiological data are needed to design effective infection control interventions.

  17. Effect of carbapenem consumption patterns on the molecular epidemiology and carbapenem resistance of Acinetobacter baumannii.

    Science.gov (United States)

    Mózes, Julianna; Ebrahimi, Fatemeh; Gorácz, Orsolya; Miszti, Cecília; Kardos, Gábor

    2014-12-01

    This study investigated the molecular epidemiology of Acinetobacter baumannii in the University of Debrecen in relation to antibiotic consumption. Overall and ward-specific antibiotic consumption was measured by the number of defined daily doses (DDD) per 100 bed-days between 2002 and 2012. Consumption was analysed against the number of A. baumannii positive patients per 100 bed-days, number of isolates per positive sample, and proportion of carbapenem resistant A. baumannii, using time-series analysis. Altogether 160 A. baumannii isolates from different wards were collected and analysed. Carbapenemase genes bla(OXA-23-like), bla(OXA-24-like), bla(OXA-48-like), bla(OXA-51-like), bla(OXA-58-like) and integrons were sought by PCR. Relatedness of isolates was assessed by PFGE. Prevalence and carbapenem resistance of A. baumannii were statistically associated with carbapenem consumption. Prevalence data followed carbapenem usage with three quarterly lags (r = 0.51-0.53, Pcarbapenem consumption was associated with the carbapenem-susceptible cluster, as well as with the carbapenem-susceptible isolates in the cluster with variable susceptibility. Wards with high carbapenem usage almost exclusively harboured isolates from carbapenem-resistant clusters. All clusters were dominated by isolates of one or two wards, but most wards were represented in multiple clusters. Increases in prevalence and carbapenem resistance of A. baumannii were associated with usage of meropenem and ertapenem but not of imipenem, which led to the spread of multiple clones in the University. © 2014 The Authors.

  18. Susceptibility to tigecycline of Acinetobacter baumannii strains isolated from intensive care unit patients.

    Science.gov (United States)

    Talaga, Katarzyna; Krzyściak, Paweł; Bulanda, Małgorzata

    2016-01-01

    Infections caused by Acinetobacter baumannii are difficult to cure due to the acquisition of resistance by these bacteria and lead to an increase in the general costs of hospitalization. The aim of this study was to determine tigecycline susceptibility of Acinetobacter baumannii strains isolated from intensive care unit and non-intensive care unit patients with skin and soft tissue infections. MICs were tested by Etest among 70 Acinetobacter baumannii isolates. The MIC range was from 0.5 to 8.0 mg L⁻¹. For ESBL-producing Acinetobacter baumannii, as well as for strains without carbapenemases, the highest MIC to tigecycline value was 8.0 mg L⁻¹. For AmpC-producing Acinetobacter baumannii, the highest MIC to tigecycline value was 6.0 mg L⁻¹ and, for MBL-producing strains, 2.0 mg L⁻¹. The majority of Acinetobacter baumannii strains isolated from ICU and non-ICU patients demonstrated high values of MIC range, MIC50 and MIC90 to tigecycline.

  19. Code blue: Acinetobacter baumannii, a nosocomial pathogen with a role in the oral cavity

    Science.gov (United States)

    Richards, A.M.; Kwaik, Y. Abu; Lamont, R.J.

    2015-01-01

    SUMMARY Actinetobacter baumannii is an important nosocomial pathogen that can cause a wide range of serious conditions including pneumonia, meningitis, necrotizing fasciitis and sepsis. It is also a major cause of wound infections in military personnel injured during the conflicts in Afghanistan and Iraq, leading to its popular nickname of ‘Iraqibacter’. Contributing to its success in clinical settings is resistance to environmental stresses such as desiccation and disinfectants. Moreover, in recent years there has been a dramatic increase in the number of A. baumannii strains with resistance to multiple antibiotic classes. Acinetobacter baumannii is an inhabitant of oral biofilms, which can act as a reservoir for pneumonia and chronic obstructive pulmonary disease. Subgingival colonization by A. baumannii increases the risk of refractory periodontitis. Pathogenesis of the organism involves adherence, biofilm formation and iron acquisition. In addition, A. baumannii can induce apoptotic cell death in epithelial cells and kill hyphal forms of Candida albicans. Virulence factors that have been identified include pili, the outer membrane protein OmpA, phospholipases and extracellular polysaccharide. Acinetobacter baumannii can sense blue light through a blue-light sensing using flavin (BLUF) domain protein, BlsA. The resulting conformational change in BlsA leads to changes in gene expression, including virulence genes. PMID:25052812

  20. Acinetobacter calcoaceticus-Acinetobacter baumannii complex species in clinical specimens in Singapore.

    Science.gov (United States)

    Koh, T H; Tan, T T; Khoo, C T; Ng, S Y; Tan, T Y; Hsu, L-Y; Ooi, E E; Van Der Reijden, T J K; Dijkshoorn, L

    2012-03-01

    This study was performed to determine the prevalence, distribution of specimen sources, and antimicrobial susceptibility of the Acinetobacter calcoaceticus-Acinetobacter baumannii (Acb) species complex in Singapore. One hundred and ninety-three non-replicate Acb species complex clinical isolates were collected from six hospitals over a 1-month period in 2006. Of these, 152 (78·7%) were identified as A. baumannii, 18 (9·3%) as 'Acinetobacter pittii' [genomic species (gen. sp.) 3], and 23 (11·9%) as 'Acinetobacter nosocomialis' (gen. sp. 13TU). Carbapenem resistance was highest in A. baumannii (72·4%), followed by A. pittii (38·9%), and A. nosocomialis (34·8%). Most carbapenem-resistant A. baumannii and A. nosocomialis possessed the bla(OXA-23-like) gene whereas carbapenem-resistant A. pittii possessed the bla(OXA-58-like) gene. Two imipenem-resistant strains (A. baumannii and A. pittii) had the bla(IMP-like) gene. Representatives of carbapenem-resistant A. baumannii were related to European clones I and II.

  1. Aptamer-nanobody based ELASA for specific detection of Acinetobacter baumannii isolates.

    Science.gov (United States)

    Rasoulinejad, Samaneh; Gargari, Seyed Latif Mousavi

    2016-08-10

    Acinetobacter baumannii has turned into an important threat in nosocomial outbreak infections and multidrug resistance leading to high mortality rates in the 21st century. In recent years its mortality has increased by 15% which in part could be due to lack of a rapid and sensitive diagnostic test. In this work we introduced a new detection test for A. baumannii with two highly specific aptamer and nanobody molecules. High binding affinity DNA oligonucleotide aptamers toward A. baumannii were selected through 12 rounds of whole cell System Evolution of Ligands by EXponential enrichment process (SELEX). The SELEX procedures was monitored by flow cytometry. The dissociation constant and binding efficiency of the selected aptamer Aci49 was 7.547±1:353pM and 47.50%, respectively. A sandwich enzyme linked aptamer sorbent assay (ELASA) was designed with the biotinylated Aci49 aptamer and our previously developed nanobody against biofilm associated protein (Bap). The assay system was optimized with A. baumannii (ATCC 19606) and 47 clinical isolates of A. baumannii were tested. The threshold of detection in sandwich ELASA process was10(3) CFU/ml. The sensitivity of test toward the clinical isolates was 95.47%. Our results reveal that the sandwich ELASA is sensitive and specific enough for the rapid detection of A. baumannii from clinical isolates. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Molecular Typing of Acinetobacter Baumannii Clinical Strains in Tehran by Pulsed-Field Gel Electrophoresis

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    Neda Farahani

    2013-03-01

    Full Text Available Background & Objective : Currently, Acinetobacter baumannii is an important nosocomial pathogen insofar as its hospital outbreaks have been described from various geographical areas. Since the discrimination of strains within a species is important for delineating nosocomial outbreaks, this study was conducted with the aim of genotyping the A. baumannii clinical strains in Tehran via the pulsed-field gel electrophoresis (PFGE method, which is the most accurate method used for the typing of bacterial species.   Materials & methods: This study was performed on 70 isolates of acinetobacter baumannii isolated from patients from Baqiyatallah, Rasoole Akram, and Milad hospitals in Tehran. Cultural and biochemical methods were used for the identification of the isolates in species level, and then susceptibility tests were carried out on 50 isolates of A. baumannii using the disk diffusion method. The PFGE method was performed on the isolates by Apa I restriction enzyme. Finally, the results of the PFGE were analyzed. Result: Acinetobacter baumannii strains isolated from hospitals in Tehran showed seven different genetic patterns, two of which were sporadic . Also, genotypic profiles were different in each hospital, and different patterns of genetic resistance to common antibiotics were observed. Conclusion: A lthough diversity was observed among the strains of A. baumannii by the PFGE method in Tehran, no epidemic strains were found among them.  

  3. Modulating Acinetobacter baumannii biofilm development with molecules containing 3,4,5-trimethoxy-N,N',N'-trimethylbenzohydrazide moiety.

    Science.gov (United States)

    Sambanthamoorthy, Karthik; Hickman, Mark; Pattabiraman, Nagarajan; Palys, Thomas; Wagar, Eric J

    2015-01-01

    In recent years, Acinetobacter baumannii has emerged as a major cause of nosocomial infections, including infections of implanted medical devices. The treatment of infections caused by A. baumannii has been severely hampered due to their frequent resistance to currently available antibiotics, and most importantly the ability of A. baumannii to form biofilms, which plays a significant role in both persistence and antibiotic resistance. The inherent resistance of A. baumannii biofilms to host defenses and antimicrobial agents necessitates the search for novel approaches to deter biofilm formation. Here, we report our findings on nine compounds identified from structure-activity relationship (SAR) studies on an antibiofilm compound LP3134 that was reported earlier by Biofouling2014, 30, 17. Compounds were evaluated for antibiofilm and anti-adherence activities against A. baumannii. The ability of the compounds to prevent biofilm development on urinary catheters was studied. Growth curve experiments indicated that compounds did not affect the planktonic growth of A. baumannii. All compounds inhibited A. baumannii biofilm development as well as impacting early adhesion on abiotic surfaces. Seven compounds were able to deter biofilm development on silicone catheters. Due to the continued rise of emerging multidrug-resistant A. baumannii, results from this study provide foundation for further development of these molecules to treat A. baumannii infections in wounds and medical devices. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Differences in Acinetobacter baumannii strains and host innate immune response determine morbidity and mortality in experimental pneumonia.

    Directory of Open Access Journals (Sweden)

    Anna de Breij

    Full Text Available Despite many reports documenting its epidemicity, little is known on the interaction of Acinetobacter baumannii with its host. To deepen our insight into this relationship, we studied persistence of and host response to different A. baumannii strains including representatives of the European (EU clones I-III in a mouse pneumonia model. Neutropenic mice were inoculated intratracheally with five A. baumannii strains and an A. junii strain and at several days morbidity, mortality, bacterial counts, airway inflammation, and chemo- and cytokine production in lungs and blood were determined. A. baumannii RUH875 and RUH134 (EU clone I and II, respectively and sporadic strain LUH8326 resulted in high morbidity/mortality, whereas A. baumannii LUH5875 (EU clone III, which is less widespread than clone I and II caused less symptoms. A. baumannii type strain RUH3023(T and A. junii LUH5851 did not cause disease. All strains, except A. baumannii RUH3023(T and A. junii LUH5851, survived and multiplied in the lungs for several days. Morbidity and mortality were associated with the severity of lung pathology and a specific immune response characterized by low levels of anti-inflammatory (IL-10 and specific pro-inflammatory (IL-12p40 and IL-23 cytokines at the first day of infection. Altogether, a striking difference in behaviour among the A. baumannii strains was observed with the clone I and II strains being most virulent, whereas the A. baumannii type strain, which is frequently used in virulence studies appeared harmless.

  5. Layouts of Expander Graphs

    OpenAIRE

    Dujmović, Vida; Sidiropoulos, Anastasios; Wood, David R.

    2015-01-01

    Bourgain and Yehudayoff recently constructed $O(1)$-monotone bipartite expanders. By combining this result with a generalisation of the unraveling method of Kannan, we construct 3-monotone bipartite expanders, which is best possible. We then show that the same graphs admit 3-page book embeddings, 2-queue layouts, 4-track layouts, and have simple thickness 2. All these results are best possible.

  6. Acinetobacter baumannii in ICU patients: A prospective study highlighting their incidence, antibiotic sensitivity pattern and impact on ICU stay and mortality

    Directory of Open Access Journals (Sweden)

    Ashraf E. Sileem

    2017-10-01

    Conclusion: Acinetobacter baumannii is not so far as a cause of nosocomial respiratory infection with subsequent long ICU stays and high mortality. Emerging A. baumannii resistant strains is considered a real threat in ICU.

  7. Frequent combination of antimicrobial multiresistance and extraintestinal pathogenicity in Escherichia coli isolates from urban rats (Rattus norvegicus in Berlin, Germany.

    Directory of Open Access Journals (Sweden)

    Sebastian Guenther

    Full Text Available Urban rats present a global public health concern as they are considered a reservoir and vector of zoonotic pathogens, including Escherichia coli. In view of the increasing emergence of antimicrobial resistant E. coli strains and the on-going discussion about environmental reservoirs, we intended to analyse whether urban rats might be a potential source of putatively zoonotic E. coli combining resistance and virulence. For that, we took fecal samples from 87 brown rats (Rattus norvegicus and tested at least three E. coli colonies from each animal. Thirty two of these E. coli strains were pre-selected from a total of 211 non-duplicate isolates based on their phenotypic resistance to at least three antimicrobial classes, thus fulfilling the definition of multiresistance. As determined by multilocus sequence typing (MLST, these 32 strains belonged to 24 different sequence types (STs, indicating a high phylogenetic diversity. We identified STs, which frequently occur among extraintestinal pathogenic E. coli (ExPEC, such as STs 95, 131, 70, 428, and 127. Also, the detection of a number of typical virulence genes confirmed that the rats tested carried ExPEC-like strains. In particular, the finding of an Extended-spectrum beta-lactamase (ESBL-producing strain which belongs to a highly virulent, so far mainly human- and avian-restricted ExPEC lineage (ST95, which expresses a serogroup linked with invasive strains (O18:NM:K1, and finally, which produces an ESBL-type frequently identified among human strains (CTX-M-9, pointed towards the important role, urban rats might play in the transmission of multiresistant and virulent E. coli strains. Indeed, using a chicken infection model, this strain showed a high in vivo pathogenicity. Imagining the high numbers of urban rats living worldwide, the way to the transmission of putatively zoonotic, multiresistant, and virulent strains might not be far ahead. The unforeseeable consequences of such an emerging public

  8. Frequent Multidrug-Resistant Acinetobacter baumannii Contamination of Gloves, Gowns, and Hands of Healthcare Workers

    Science.gov (United States)

    Morgan, Daniel J.; Liang, Stephen Y.; Smith, Catherine L.; Johnson, J. Kristie; Harris, Anthony D.; Furuno, Jon P.; Thom, Kerri A.; Snyder, Graham M.; Day, Hannah R.; Perencevich, Eli N.

    2010-01-01

    BACKGROUND Multidrug-resistant (MDR) gram-negative bacilli are important nosocomial pathogens. OBJECTIVE To determine the incidence of transmission of MDR Acinetobacter baumannii and Pseudomonas aeruginosa from patients to healthcare workers (HCWs) during routine patient care. DESIGN Prospective cohort study. SETTING Medical and surgical intensive care units. METHODS We observed HCWs who entered the rooms of patients colonized with MDR A. baumannii or colonized with both MDR A. baumannii and MDR P. aeruginosa. We examined their hands before room entry, their disposable gloves and/or gowns upon completion of patient care, and their hands after removal of gloves and/or gowns and before hand hygiene. RESULTS Sixty-five interactions occurred with patients colonized with MDR A. baumannii and 134 with patients colonized with both MDR A. baumannii and MDR P. aeruginosa. Of 199 interactions between HCWs and patients colonized with MDR A. baumannii, 77 (38.7% [95% confidence interval {CI}, 31.9%–45.5%]) resulted in HCW contamination of gloves and/or gowns, and 9 (4.5% [95% CI, 1.6%–7.4%]) resulted in contamination of HCW hands after glove removal before hand hygiene. Of 134 interactions with patients colonized with MDR P. aeruginosa, 11 (8.2% [95% CI, 3.6%–12.9%]) resulted in HCW contamination of gloves and/or gowns, and 1 resulted in HCW contamination of hands. Independent risk factors for contamination with MDR A. baumannii were manipulation of wound dressing (adjusted odds ratio [aOR], 25.9 [95% CI, 3.1–208.8]), manipulation of artificial airway (aOR, 2.1 [95% CI, 1.1–4.0]), time in room longer than 5 minutes (aOR, 4.3 [95% CI, 2.0–9.1]), being a physician or nurse practitioner (aOR, 7.4 [95% CI, 1.6–35.2]), and being a nurse (aOR, 2.3 [95% CI, 1.1–4.8]). CONCLUSIONS Gowns, gloves, and unwashed hands of HCWs were frequently contaminated with MDR A. baumannii. MDR A. baumannii appears to be more easily transmitted than MDR P. aeruginosa and perhaps more

  9. ANTIMICROBIAL SENSITIVITY OF MULTIDRUG-RESISTANT ACINETOBACTER BAUMANNII IN A TERTIARY CARE HOSPITAL OF PATNA

    Directory of Open Access Journals (Sweden)

    Keshav Kumar Bimal

    2017-06-01

    Full Text Available BACKGROUND Acinetobacter spp. has emerged as an important nosocomial pathogen especially in ICU settings. Acinetobacter baumannii is the most commonly isolated species among different Acinetobacters and is associated with variety of human infections. A. baumannii exhibits resistance not only to beta-lactams and cephalosporins, but also to other groups of antibiotics including carbapenems and this has resulted in the emergence of multidrug-resistance A. baumannii species, which is now widespread. To know the prevalence and antimicrobial susceptibility pattern of A. baumannii is crucial for the optimal antimicrobial therapy and to resist the spread of MDR Acinetobacter spp. The aim of the study is to study the antimicrobial susceptibility pattern of A. baumannii isolated from various clinical specimens and to explore the risk factors for multidrug-resistant A. baumannii infections. MATERIALS AND METHODS The present study was conducted from August 2015 to July 2016 at Indira Gandhi Institute of Medical Sciences, Patna. Antimicrobial susceptibility testing was done by Kirby-Bauer’s disc diffusion method. The zones of inhibition were interpreted for antibiotic sensitivity as per the CLSI guidelines 2014. Data regarding patients demographic and clinical status was obtained from medical records and possible risk factors for multidrug-resistant A. baumannii infections was evaluated for their statistical significance. Statistical analysis used- Microsoft excel sheet 2007 and Epi Info software (version 7.2.0.1 was used for different statistical analysis including Pearson’s x 2 test and simple logistic regression. RESULTS A. baumannii was isolated predominantly from respiratory samples (35.3%. Majority of the isolates were from different inpatient departments (59.1%, followed by different ICUs (40.9%. The A. baumannii isolates showed most sensitivity to colistin (100% followed by polymyxin B (90.20% and least sensitive to ampicillin (5.19%. Most of the

  10. The influence of carbapenem resistance on mortality in solid organ transplant recipients with Acinetobacter baumannii infection

    Directory of Open Access Journals (Sweden)

    de Gouvêa Erika

    2012-12-01

    Full Text Available Abstract Background Infection with carbapenem-resistant Acinetobacter baumannii has been associated with high morbidity and mortality in solid organ transplant recipients. The main objective of this study was to assess the influence of carbapenem resistance and other potential risk factors on the outcome of A. baumannii infection after kidney and liver transplantation. Methods Retrospective study of a case series of A. baumannii infection among liver and renal transplant recipients. The primary outcome was death associated with A. baumannii infection. Multivariate logistic regression was used to assess the influence of carbapenem resistance and other covariates on the outcome. Results Forty-nine cases of A. baumannii infection affecting 24 kidney and 25 liver transplant recipients were studied. Eighteen cases (37% were caused by carbapenem-resistant isolates. There were 17 (35% deaths associated with A. baumannii infection. In unadjusted analysis, liver transplantation (p = 0.003, acquisition in intensive care unit (p = 0.001, extra-urinary site of infection (p A. baumannii infection. The number of deaths associated with A. baumannii infection was higher among patients infected with carbapenem-resistant isolates, but the difference was not significant (p = 0.28. In multivariate analysis, the risk of A. baumannii-associated mortality was higher in patients with infection acquired in the intensive care unit (odds ratio [OR] = 34.8, p = 0.01 and on mechanical ventilation (OR = 15.2, p = 0.04. Appropriate empiric antimicrobial therapy was associated with significantly lower mortality (OR = 0.04, p = 0.03, but carbapenem resistance had no impact on it (OR = 0.73, p = 0.70. Conclusion These findings suggest that A. baumannii-associated mortality among liver and kidney transplant recipients is influenced by baseline clinical severity and by the early start of appropriate therapy, but not by carbapenem

  11. Genome Sequences of Four Acinetobacter baumannii-A. calcoaceticus Complex Isolates from Combat-Related Infections Sustained in the Middle East

    Science.gov (United States)

    2014-02-06

    baumannii -A. calcoaceticus Complex Isolates from Combat-Related Infections Sustained in the Middle East Acinetobacter baumannii is among the most...responses make treatment difficult. Here, we report the genome sequences of four clinical Acinetobacter baumannii - A. calcoaceticus complex isolates... Acinetobacter baumannii , A. calcoaceticus, combat-related infections REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S

  12. Functionalized expanded porphyrins

    Science.gov (United States)

    Sessler, Jonathan L; Pantos, Patricia J

    2013-11-12

    Disclosed are functionalized expanded porphyrins that can be used as spectrometric sensors for high-valent actinide cations. The disclosed functionalized expanded porphyrins have the advantage over unfunctionalized systems in that they can be immobilized via covalent attachment to a solid support comprising an inorganic or organic polymer or other common substrates. Substrates comprising the disclosed functionalized expanded porphyrins are also disclosed. Further, disclosed are methods of making the disclosed compounds (immobilized and free), methods of using them as sensors to detect high valent actinides, devices that comprise the disclosed compounds, and kits.

  13. Analysis of antibiotic multi-resistant bacteria and resistance genes in the effluent of an intensive shrimp farm (Long An, Vietnam).

    Science.gov (United States)

    Pham, Thi Thu Hang; Rossi, Pierre; Dinh, Hoang Dang Khoa; Pham, Ngoc Tu Anh; Tran, Phuong Anh; Ho, To Thi Khai Mui; Dinh, Quoc Tuc; De Alencastro, Luiz Felippe

    2018-05-15

    In Vietnam, intensive shrimp farms heavily rely on a wide variety of antibiotics (ABs) to treat animals or prevent disease outbreak. Potential for the emergence of multi-resistant bacteria is high, with the concomitant contamination of adjacent natural aquatic habitats used for irrigation and drinking water, impairing in turn human health system. In the present study, quantification of AB multi-resistant bacteria was carried out in water and sediment samples from effluent channels connecting a shrimp farming area to the Vam Co River (Long An Province, Vietnam). Bacterial strains, e.g. Klebsiella pneumoniae and Aeromonas hydrophila, showing multi-resistance traits were isolated. Molecular biology analysis showed that these strains possessed from four to seven different AB resistance genes (ARGs) (e.g. sul1, sul2, qnrA, ermB, tetA, aac(6)lb, dfrA1, dfr12, dfrA5), conferring multidrug resistance capacity. Sequencing of plasmids present within these multi-resistant strains led to the identification of a total of forty-one resistance genes, targeting nine AB groups. qPCR analysis on the sul2 gene revealed the presence of high copy numbers in the effluent channel connecting to the Vam Co River. The results of the present study clearly indicated that multi-resistant bacteria present in intensive shrimp cultures may disseminate in the natural environment. This study offered a first insight in the impact of plasmid-born ARGs and the related pathogenic bacteria that could emerged due to inappropriate antibiotic utilization in South Vietnam. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Identifying and controlling a multiresistant pseudomonas aeruginosa outbreak in a latin-american cancer centre and its associated risk factors

    Directory of Open Access Journals (Sweden)

    Jorge Alberto Cortes

    Full Text Available Pseudomonas aeruginosa is an important and frightening microorganism for patients suffering from cancer. Multiresistant P. aeruginosa (MRPA may appear as a consequence of exposure to multiple antibiotics or from a breakdown in infection control practices. This article reports an MRPA outbreak in a cancer treatment centre and the consequent case control study. Mechanical ventilation was identified as being the main risk factor for developing MRPA colonisation or infection; molecular analysis confirmed the outbreak. A multifaceted strategy was adopted, involving reinforcing hand-washing practices, contact isolation, antibiotic restriction and suction devices for mechanically-ventilated patients. MRPA was controlled and the outbreak ended. Such strategy may be effective in controlling MRPS in low-resource environments amongst high risk cancer patients.

  15. The Antibacterial Activity Evaluation of the Nanoparticles of Silver on Acinetobacter Baumannii

    Directory of Open Access Journals (Sweden)

    Seyedeh Nasim Karimipour

    2016-09-01

    Full Text Available Background & Objective: Due to the high drug resistance in Acinetobacter baumannii, in this research, antibacterial properties of nano silver was evaluated for Acinetobacter baumannii. Materials & Methods: The nano silver with approximate diameter of 20 nanometer from Pishtazan Inc. Mashad, Iran and 5 nanometer from the Department of Chemistry in Maragheh University were prepared. Its concentration was determined by spectroscopy method in Tabriz Chemistry University.  Antimicrobial effects were determined by Mean Inhibitory Concentration (MIC and Minimal Bacterial Concentration (MBC by micro-broth-dilution method, disc diffusion and well diffusion methods. Anti-bacterial activity of nano-silver was tested for Acinetobacter baumannii NCTC12516 on 20 clinical strains (collected from Imam Reza Hospital in Tabriz. Results: The results showed the MIC and MBC of 20nm nanoparticles were 1250 ppm and 2500 ppm, respectively. On the other hand, the MIC and MBC of 5 nm nanoparticles were 156 ppm and 312 ppm, respectively. According to these findings, the MIC and MBC identified for clinical Acinetobacter baumannii strains under study along with the NCTC12516 strain did not show a significant difference. Yet the amount of inhibition for the 20nm nanoparticles in the density of 20000 ppm of clinical Acinetobacter baumannii and NCTC12516 strains was 11 millimeter with the disc diffusion method and 9.5 millimeter for the well diffusion method with the same concentration. The amount of inhibition of 5nm nanoparticles in the 250-ppm concentration with both disc diffusion and well diffusion methods was 9.5 millimeter. Conclusions: Acinetobacter baumannii is susceptible to nano-silver. Also the same MIC and MBC in multiple clinical strains suggests that there is not resistance to silver nanoparticles in Acinetobacter baumannii

  16. Evolution of Acinetobacter baumannii In Vivo: International Clone II, More Resistance to Ceftazidime, Mutation in ptk

    Directory of Open Access Journals (Sweden)

    Xiaoting Hua

    2017-07-01

    Full Text Available Acinetobacter baumannii is an important nosocomial pathogen worldwide. A more comprehensive understanding of the within-host genomic evolution of A. baumannii would provide a molecule basis for improving treatment of A. baumannii infection. To understand the evolutionary mechanism facilitating A. baumannii survived in human body, we here reported the genomic analysis of A. baumannii isolated sampled from Chinese patients. We used whole-genome sequence of A. baumannii isolates from the same patient to determine single-nucleotide variants, insertion sequence mapping, and gene change. The MICs for 10 antimicrobial agents were determined. Motility assay and microscopy were performed on the isolated pairs harboring ptk mutations. The gene ptk encoded a putative protein tyrosine kinase involved in the production of capsular polysaccharide. Approximately half (39/86 of the strains isolated from the same patient harbored the same MLST patterns, and during the replacement of international clonal lineage II (ICL-II and non-ICL-II strains, most of the alteration was that non-ICL-II strain was replaced by ICL-II strain (10/12. A. baumannii was resistant to major antimicrobial agents, whereas the strains were more resistant to ceftazidime, azithromycin, and sulfonamides after within-host evolution. Isolates from the ICL-II lineage displayed greater resistance to antimicrobial agents than non-ICL-II isolates. Isolates from ICL-II harbored more resistance genes and mobile elements than non-ICL-II strains. Several lineages evolved a more mucoid phenotype. Genome sequencing revealed that the phenotype was achieved by genetic changes in the ptk gene. ICL-II (especially ST195 and ST208 was the terminal destination for bacteria after within-host evolution. These results indicate that the molecular basis and the treatment for ICL-II strains needed further investigation.

  17. OmpA Binding Mediates the Effect of Antimicrobial Peptide LL-37 on Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Ming-Feng Lin

    Full Text Available Multidrug-resistant Acinetobacter baumannii has recently emerged as an important pathogen in nosocomial infection; thus, effective antimicrobial regimens are urgently needed. Human antimicrobial peptides (AMPs exhibit multiple functions and antimicrobial activities against bacteria and fungi and are proposed to be potential adjuvant therapeutic agents. This study examined the effect of the human cathelicidin-derived AMP LL-37 on A. baumannii and revealed the underlying mode of action. We found that LL-37 killed A. baumannii efficiently and reduced cell motility and adhesion. The bacteria-killing effect of LL-37 on A. baumannii was more efficient compared to other AMPs, including human ß-defensin 3 (hBD3 and histatin 5 (Hst5. Both flow cytometric analysis and immunofluorescence staining showed that LL-37 bound to A. baumannii cells. Moreover, far-western analysis demonstrated that LL-37 could bind to the A. baumannii OmpA (AbOmpA protein. An ELISA assay indicated that biotin-labelled LL-37 (BA-LL37 bound to the AbOmpA74-84 peptide in a dose-dependent manner. Using BA-LL37 as a probe, the ~38 kDa OmpA signal was detected in the wild type but the ompA deletion strain did not show the protein, thereby validating the interaction. Finally, we found that the ompA deletion mutant was more sensitive to LL-37 and decreased cell adhesion by 32% compared to the wild type. However, ompA deletion mutant showed a greatly reduced adhesion defect after LL-37 treatment compared to the wild strain. Taken together, this study provides evidence that LL-37 affects A. baumannii through OmpA binding.

  18. Carbapenem-resistant Acinetobacter baumannii contamination in an intensive care unit

    Directory of Open Access Journals (Sweden)

    Otávio Hallal Ferreira Raro

    Full Text Available Abstract INTRODUCTION: Acinetobacter baumannii is a major pathogen causing infections in intensive care units (ICUs. In this study, we aimed to evaluate the presence of A. baumannii in an ICU environment and gloves from ICU workers and to characterize the antimicrobial resistance of the isolates in comparison with those isolated from ICU patients at the same hospital. METHODS: ICU samples were collected from March to November 2010. Isolates biochemically characterized as Acinetobacter calcoaceticus-Acinetobacter baumannii complex were evaluated by PCR targeting the 16S rDNA and bla OXA-51 genes. Antimicrobial susceptibility was determined using the disk diffusion method, and carbapenem-resistant isolates were also evaluated for the minimum inhibitory concentration of imipenem using broth microdilution. The presence of the bla OXA-23 gene was evaluated in isolates with reduced susceptibility to carbapenems. RESULTS: A. baumannii was detected in 9.5% (84 of the 886 samples collected from the ICU environment, including from furniture, medical devices, and gloves, with bed rails being the most contaminated location (23.8%; 20/84. Multidrug-resistant (MDR A. baumannii was found in 98.8% (83/84 of non-clinical and 97.8% (45/46 of clinical isolates. Reduced susceptibility to carbapenems was detected in 83.3% (70/84 of non-clinical and 80.4% (37/46 of clinical isolates. All isolates resistant to carbapenems harbored bla OXA-23. CONCLUSIONS: We found a strong similarity between the antimicrobial susceptibility profiles of non-clinical and clinical A. baumannii isolates. Such data highlight the ICU environment as a potential origin for the persistence of MDR A. baumannii, and hence the ICU may be a source of hospital-acquired infections caused by this microorganism.

  19. Multiresistant extended-spectrum β-lactamase-producing Enterobacteriaceae from humans, companion animals and horses in central Hesse, Germany

    Science.gov (United States)

    2014-01-01

    Background Multiresistant Gram-negative bacteria producing extended-spectrum β-lactamases (ESBLs) are an emerging problem in human and veterinary medicine. This study focused on comparative molecular characterization of β-lactamase and ESBL-producing Enterobacteriaceae isolates from central Hesse in Germany. Isolates originated from humans, companion animals (dogs and cats) and horses. Results In this study 153 (83.6%) of the human isolates (n = 183) and 163 (91.6%) of the animal isolates (n = 178) were confirmed as ESBL producers by PCR and subsequent sequencing of the PCR amplicons. Predominant ESBL subtypes in human and animal samples were CTX-M-15 (49.3%) and CTX-M-1 (25.8%) respectively. Subtype blaCTX-M-2 was found almost exclusively in equine and was absent from human isolates. The carbapenemase OXA-48 was detected in 19 ertapenem-resistant companion animal isolates in this study. The Plasmid-encoded quinolone resistance (PMQR) gene aac(‘6)-Ib-cr was the most frequently detected antibiotic- resistance gene present in 27.9% of the human and 36.9% of the animal ciprofloxacin-resistant isolates. Combinations of two or up to six different resistance genes (penicillinases, ESBLs and PMQR) were detected in 70% of all isolates investigated. The most frequent species in this study was Escherichia coli (74%), followed by Klebsiella pneumoniae (17.5%), and Enterobacter cloacae (4.2%). Investigation of Escherichia coli phylogenetic groups revealed underrepresentation of group B2 within the animal isolates. Conclusions Isolates from human, companion animals and horses shared several characteristics regarding presence of ESBL, PMQR and combination of different resistance genes. The results indicate active transmission and dissemination of multi-resistant Enterobacteriaceae among human and animal populations. PMID:25014994

  20. Expanding Thurston maps

    CERN Document Server

    Bonk, Mario

    2017-01-01

    This monograph is devoted to the study of the dynamics of expanding Thurston maps under iteration. A Thurston map is a branched covering map on a two-dimensional topological sphere such that each critical point of the map has a finite orbit under iteration. It is called expanding if, roughly speaking, preimages of a fine open cover of the underlying sphere under iterates of the map become finer and finer as the order of the iterate increases. Every expanding Thurston map gives rise to a fractal space, called its visual sphere. Many dynamical properties of the map are encoded in the geometry of this visual sphere. For example, an expanding Thurston map is topologically conjugate to a rational map if and only if its visual sphere is quasisymmetrically equivalent to the Riemann sphere. This relation between dynamics and fractal geometry is the main focus for the investigations in this work.

  1. [Effect of MTRR gene on apoptosis and autophagy pathways in multiresistant epithelial ovarian cancer].

    Science.gov (United States)

    Chen, J; Wang, Q; Zhang, W; Li, L

    2016-04-25

    To explore the effect of down-regulated methionine synthase reductase(MTRR)gene on the apoptosis and autophagy pathway, and offer a possible approach for the MTRR to reverse the multi-resistant ovarian cancer. (1)The experiment was divided into 3 groups, SKOV3/DDP-MTRRi(down-regulated MTRR group), SKOV3/DDP-NC(negative control group), and SKOV3/DDP(blank control group). Different concentration of cisplatin(0, 1, 2, and 4 μg/ml)treated on 3 groups cells. The apoptosis rate was measured by flow cytometry(FCM). Autophagy was detected by immunofluorescence. Autophagy microtubule associated protein light chain 3β(LC3B)and p62 were detected by western blot. The formation of autophagosome of cells was observed by transmission electron microscope.(2)Detection of autophagy and apoptosis of SKOV3/DDP-MTRRi induced by rapamycin. The experiment was divided into 4 groups included rapamycin group(5 nmol/L rapamycin), rapamycin+cisplatin group(5 nmol/L rapamycin+ 4 μg/ml cisplatin), cisplatin group(4 μg/ml cisplatin)and blank control group. LC3B and p62 protein were detected by western blot. The survival rate cells were detected by methyl thiazolyl tetrazolium(MTT)method. The apoptosis rate was measured by FCM.(3)The 3 groups cells(SKOV3/DDP, SKOV3/DDP-NC and SKOV3/DDP-MTRRi)induced by a certain concentration of cisplatin(4 μg/ml)after 48 hours, then detecting the protein expression of caspase, Bcl-2 family in apoptosis pathway and the key proteins in phosphatidylinositol-3 kinase(PI3K)/protein kinase B(Akt)autophagy pathways by western blot, getting the time when the proteins' expression changed. (1)The 3 groups cells(SKOV3/DDP, SKOV3/DDP-NC, and SKOV3/DDP-MTRRi)induced by a certain concentration of cisplatin(4 μg/ml)after 48 hours, apoptosis and autophagy of 3 groups of cells were gradually increased with the increased concentration of cisplatin. The apoptosis rate of SKOV3/DDP-MTRRi cells[(26.2 ± 1.4)%]were significantly increased compared with the SKOV3/DDP-NC cells or

  2. Comparison of culture media for detection of Acinetobacter baumannii in surveillance cultures of critically-ill patients.

    Science.gov (United States)

    Ajao, A O; Robinson, G; Lee, M S; Ranke, T D; Venezia, R A; Furuno, J P; Harris, A D; Johnson, J K

    2011-11-01

    The objective of this study was to evaluate the performance of CHROMagar Acinetobacter when compared to sheep blood agar, MacConkey agar and MacConkey agar with 6 μg/ml of imipenem for the detection of A. baumannii in surveillance cultures of hospitalized patients. We utilized peri-anal swabs and sputum samples from patients admitted to the University of Maryland Medical Center ICUs from December 7 through December 21, 2009. Samples were plated onto four media in the following order: (1) 5% sheep blood agar (SBA), (2) MacConkey agar, (3) MacConkey agar with 6 μg/ml of imipenem, and (4) CHROMagar Acinetobacter (CHROMagar). SBA was the gold standard to which all media was compared. There were 165 samples collected during the study period. SBA and CHROMagar detected 18 of 18 (100%) Acinetobacter and 11 of 11 (100%) MDR-A. baumannii. MacConkey agar detected 16 of 18 (89%) Acinetobacter and 10 of 11 (91%) MDR- A. baumannii while MacConkey agar with 6 μg/ml imipenem detected 9 of 11 (82%) MDR-A. baumannii. CHROMagar did not differentiate MDR- A. baumannii from non-MDR-A. baumannii. CHROMagar may be useful for rapid detection of patients with MDR-A. baumannii if improved upon to better select for MDR-A. baumannii.

  3. Characterization of a highly virulent and antimicrobial-resistant Acinetobacter baumannii strain isolated from diseased chicks in China.

    Science.gov (United States)

    Liu, Dong; Liu, Zeng-Shan; Hu, Pan; Hui, Qi; Fu, Bao-Quan; Lu, Shi-Ying; Li, Yan-Song; Zou, De-Ying; Li, Zhao-Hui; Yan, Dong-Ming; Ding, Yan-Xia; Zhang, Yuan-Yuan; Zhou, Yu; Liu, Nan-Nan; Ren, Hong-Lin

    2016-08-01

    Poultry husbandry is a very important aspect of the agricultural economy in China. However, chicks are often susceptible to infectious disease microorganisms, such as bacteria, viruses and parasites, causing large economic losses in recent years. In the present study, we isolated an Acinetobacter baumannii strain, CCGGD201101, from diseased chicks in the Jilin Province of China. Regression analyses of virulence and LD50 tests conducted using healthy chicks confirmed that A. baumannii CCGGD201101, with an LD50 of 1.81 (±0.11) × 10(4) CFU, was more virulent than A. baumannii ATCC17978, with an LD50 of 1.73 (±0.13) × 10(7) CFU. Moreover, TEM examination showed that the pili of A. baumannii CCGGD201101 were different from those of ATCC17978. Antibiotic sensitivity analyses showed that A. baumannii CCGGD201101 was sensitive to rifampicin but resistant to most other antibiotics. These results imply that A. baumannii strain CCGGD201101 had both virulence enhancement and antibiotic resistance characteristics, which are beneficial for A. baumannii survival under adverse conditions and enhance fitness and invasiveness in the host. A. baumannii CCGGD20101, with its high virulence and antimicrobial resistance, may be one of the pathogens causing death of diseased chicks. © 2016 The Societies and John Wiley & Sons Australia, Ltd.

  4. Frequency of Class 1 Integron and Genetic Diversity ofAcinetobacter baumanniiIsolated from Medical Centers in Kermanshah.

    Science.gov (United States)

    Eghbalimoghadam, Mahsa; Farahani, Abbas; Akbar, Farahtaj Navab; Mohajeri, Parviz

    2017-01-01

    Acinetobacter baumannii has emerged as an important pathogen in hospital and environment that can acquire transport element and antibiotic-resistant genes. The aim of this study was to determine the resistances to different antibiotics, frequency of Class 1 integron in A. baumannii and then molecular typing for A. baumannii isolated from Intensive Care Unit (ICU). A total of 100 isolates of A. baumannii were collected from patients admitted to hospitals in Kermanshah from April 2014 to September 2015. The isolates were identified using biochemical test. Antimicrobial susceptibility test for 20 antibiotics was determined by Kirby-Bauer antibiotic testing (or disc diffusion). The prevalence rate of class integrons among the isolates was determined using polymerase chain reaction and finally 80 isolates of A. baumannii obtained from the Intensive Care Unit were selected for molecular typing by pulsed-field gel electrophoresis (PFGE). The maximum drug resistance was observed against cefotaxime, ceftriaxone, mezlocillin, imipenem, and ceftazidime and piperacillin. Twenty-nine isolates were multidrug resistant (MDR); about 21 isolates were extensively-drug resistant and none were pandrug resistance and 42 isolates (42%) contained Class 1 integrons. The results did not show a significant correlation between the presence of Class 1 integrons and incidence of MDR A. baumannii . Five clusters were obtained by PFGE. This study did not show a significant correlation between the presence of Class 1 integrons and incidence of MDR A. baumannii . By PFGE analysis, the high level of similarity between some pulsotypes in A. baumannii strains showed genetic correlation between them.

  5. Whole-genome pyrosequencing of an epidemic multidrug-resistant Acinetobacter baumannii strain belonging to the European clone II group

    DEFF Research Database (Denmark)

    Iacono, M.; Villa, L.; Fortini, D.

    2008-01-01

    The whole-genome sequence of an epidemic, multidrug-resistant Acinetobacter baumannii strain (strain ACICU) belonging to the European clone II group and carrying the plasmid-mediated bla(OXA-58) carbapenem resistance gene was determined. The A. baumannii ACICU genome was compared with the genomes...

  6. Diversity of Acinetobacter baumannii strains isolated in humans, companion animals, and the environment in Reunion Island: an exploratory study

    Directory of Open Access Journals (Sweden)

    Hélène Pailhoriès

    2015-08-01

    Conclusions: This study shows that A. baumannii strains are present outside the hospital setting in Reunion Island and show great diversity. Further studies are needed to explore these extra-hospital reservoirs of A. baumannii in Reunion Island in greater detail and to determine their possible means of dissemination.

  7. Identification of novel vaccine candidates against multidrug-resistant Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Danilo G Moriel

    Full Text Available Acinetobacter baumannii is an emerging opportunistic bacterium associated with nosocomial infections in intensive care units. The alarming increase in infections caused by A. baumannii is strongly associated with enhanced resistance to antibiotics, in particular carbapenems. This, together with the lack of a licensed vaccine, has translated into significant economic, logistic and health impacts to health care facilities. In this study, we combined reverse vaccinology and proteomics to identify surface-exposed and secreted antigens from A. baumannii. Using in silico prediction tools and comparative genome analysis in combination with in vitro proteomic approaches, we identified 42 antigens that could be used as potential vaccine targets. Considering the paucity of effective antibiotics available to treat multidrug-resistant A. baumannii infections, these vaccine targets may serve as a framework for the development of a broadly protective multi-component vaccine, an outcome that would have a major impact on the burden of A. baumannii infections in intensive care units across the globe.

  8. Detection of colistin sensitivity in clinical isolates of Acinetobacter baumannii in Iran

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    Bahareh Vakili

    2014-01-01

    Full Text Available Background: Nosocomial infection caused by Acinetobacter baumannii has emerged as a serious problem world-wide. Finding the suitable drug is an important priority. The aim of this study was to determine colistin (polymyxin E resistance in clinical isolates of A. baumannii from intensive care units (ICUs of Al Zahra Hospital. Materials and Methods: Sixty isolates of A. baumannii from patients hospitalized in ICU (Al Zahra Hospital, Isfahan University of Medical Sciences [IUMS] were studied. All isolates of A. baumannii were tested for colistin susceptibility by Eopsilometer test (E-test. Results: Of the 60 isolates 57, (95% were multidrug resistant (MDR and 76.6% (46/60 were highly resistant. The rate of colistin resistant with the E-test method was 11.6% (7/60. Conclusion: As the frequency of resistance to colistin is low, it can be used as an easily available drug for treatment of MDR A. baumannii strains, which are susceptible to colistin.

  9. Identification of aac(2')-I type b aminoglycoside-modifying enzyme genes in resistant Acinetobacter baumannii.

    Science.gov (United States)

    Lin, T; Tang, C G; Li, Q H; Ji, J; Ge, H Y; Zhang, X Y; Sun, H P

    2015-03-13

    The aim of this study was to investigate the mechanism underlying the drug resistance of Acinetobacter baumannii toward aminoglycosides. A total of 32 A. baumannii strains were identified by molecular identification and subsequently isolated. The isolates were then amplified by polymerase chain reaction to analyze the 9 aminoglycoside-modifying enzyme genes and 7 16S rRNA methylase genes. Five types of aminoglycoside-modifying enzyme genes and 1 type of 16S rRNA methylase gene were detected in the 32 drug-resistant A. baumannii strains. Positive genes included 7 detection modes, of which the all-6-gene-positive mode aac(2')-Ib+aac(3)-I+aac(6')-Ib+ant(3'')-I+aph(3')-I+armA exhibited the largest number of strains (12, 37.5%). The resistance of A. baumannii against aminoglycosides resulted from the presence of 5 types of aminoglycoside-modifying enzyme genes and the 16S rRNA methylase gene armA. This study is the first to isolate the aac(2')-Ib aminoglycoside-modifying enzyme gene from A. baumannii in a domestic clinical setting.

  10. Antibiotic Resistance Determinant-Focused Acinetobacter baumannii Vaccine Designed Using Reverse Vaccinology

    Directory of Open Access Journals (Sweden)

    Zhaohui Ni

    2017-02-01

    Full Text Available As one of the most influential and troublesome human pathogens, Acinetobacter baumannii (A. baumannii has emerged with many multidrug-resistant strains. After collecting 33 complete A. baumannii genomes and 84 representative antibiotic resistance determinants, we used the Vaxign reverse vaccinology approach to predict classical type vaccine candidates against A. baumannii infections and new type vaccine candidates against antibiotic resistance. Our genome analysis identified 35 outer membrane or extracellular adhesins that are conserved among all 33 genomes, have no human protein homology, and have less than 2 transmembrane helices. These 35 antigens include 11 TonB dependent receptors, 8 porins, 7 efflux pump proteins, and 2 fimbrial proteins (FilF and CAM87009.1. CAM86003.1 was predicted to be an adhesin outer membrane protein absent from 3 antibiotic-sensitive strains and conserved in 21 antibiotic-resistant strains. Feasible anti-resistance vaccine candidates also include one extracellular protein (QnrA, 3 RND type outer membrane efflux pump proteins, and 3 CTX-M type β-lactamases. Among 39 β-lactamases, A. baumannii CTX-M-2, -5, and -43 enzymes are predicted as adhesins and better vaccine candidates than other β-lactamases to induce preventive immunity and enhance antibiotic treatments. This report represents the first reverse vaccinology study to systematically predict vaccine antigen candidates against antibiotic resistance for a microbial pathogen.

  11. Nosocomial Infections Caused by Acinetobacter baumannii: Are We Losing the Battle?

    Science.gov (United States)

    Protic, Dragana; Pejovic, Aleksa; Andjelkovic, Dragana; Djukanovic, Nina; Savic, Dragana; Piperac, Pavle; Markovic Denic, Ljiljana; Zdravkovic, Marija; Todorovic, Zoran

    2016-04-01

    The incidence of nosocomial infections caused by multi-drug- and extended-drug resistant strains of Acinetobacter is constantly increasing all over the world, with a high mortality rate. We analyzed the in-hospital data on the sensitivity of Acinetobacter baumannii isolates and correlated them with antibiotic treatment and clinical outcomes of nosocomial infections over a 17-mo period. Retrospective analysis was performed at the Clinical Center "Bezanijska kosa," Belgrade, Serbia. Microbiologic data (number and sensitivity of A. baumannii isolates) and clinical data (medical records of 41 randomly selected patients who developed nosocomial infection caused by A. baumannii) were matched. Acinetobacter baumannii, detected in 279 isolates and obtained from 19 patients (12% of all samples), was resistant to almost all antibiotics tested, including carbapenems, with the exception of colistin and tigecycline. It was obtained most often from the respiratory tract samples. Empiric treatment of the nosocomial infections (pneumonia in 75% of cases) involved cephalosporins, metronidazole, and carbapenems (80%, 66%, and 61% of patients, respectively), whereas tigecyclin and colistin were used primarily in targeted therapy (20% and 12% of patients, respectively). The mortality rate of patients treated empirically was significantly higher (p Nosocomial A. baumannii infections represent a significant clinical problem because of their high incidence, lack of susceptibility to the most commonly used antibiotics, and the often inappropriate treatment, which favors the development of multi-drug-resistant strains.

  12. A novel series of enoyl reductase inhibitors targeting the ESKAPE pathogens, Staphylococcus aureus and Acinetobacter baumannii.

    Science.gov (United States)

    Kwon, Jieun; Mistry, Tina; Ren, Jinhong; Johnson, Michael E; Mehboob, Shahila

    2018-01-01

    S. aureus and A. baumannii are among the ESKAPE pathogens that are increasingly difficult to treat due to the rise in the number of drug resistant strains. Novel therapeutics targeting these pathogens are much needed. The bacterial enoyl reductase (FabI) is as potentially significant drug target for developing pathogen-specific antibiotics due to the presence of alternate FabI isoforms in many other bacterial species. We report the identification and development of a novel N-carboxy pyrrolidine scaffold targeting FabI in S. aureus and A. baumannii, two pathogens for which FabI essentiality has been established. This scaffold is unrelated to other known antibiotic families, and FabI is not targeted by any currently approved antibiotic. Our data shows that this scaffold displays promising enzyme inhibitory activity against FabI from both S. aureus and A. baumannii, as well as encouraging antibacterial activity in S. aureus. Compounds also display excellent synergy when combined with colistin and tested against A. baumannii. In this combination the MIC of colistin is reduced by 10-fold. Our first generation compound displays promising enzyme inhibition, targets FabI in S. aureus with a favorable selectivity index (ratio of cytotoxicity to MIC), and has excellent synergy with colistin against A. baumannii, including a multidrug resistant strain. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Antibacterial properties of Acinetobacter baumannii phage Abp1 endolysin (PlyAB1).

    Science.gov (United States)

    Huang, Guangtao; Shen, Xiaodong; Gong, Yali; Dong, Zhiwei; Zhao, Xia; Shen, Wei; Wang, Jing; Hu, Fuquan; Peng, Yizhi

    2014-12-12

    Acinetobacter baumannii has emerged as one of the most important hospital-acquired pathogens in the world, because of its resistance to almost all available antibiotic drugs. Endolysins from phages are attracting increasing interest as potential antimicrobial agents, especially for drug-resistant bacteria. We previously isolated and characterized Abp1, a virulent phage targeting the multidrug-resistant A. baumannii strain, AB1. To evaluate the antimicrobial potential of endolysin from the Abp1 phage, the endolysin gene plyAB1 was cloned and over-expressed in Escherichia coli, and the lytic activity of the recombinant protein (PlyAB1) was tested by turbidity assessment and bacteria counting assays. PlyAB1 exhibits a marked lytic activity against A. baumannii AB1, as shown by a decrease in the number of live bacteria following treatment with the enzyme. Moreover, PlyAB1 displayed a highly specific lytic effect against all of the 48 hospital-derived pandrug-resistant A. baumannii isolates that were tested. These isolates were shown to belong to different ST clones by multilocus sequence typing. The results presented here show that PlyAB1 has potential as an antibiotic against drug-resistant A. baumannii.

  14. Antibiotic Resistance Determinant-Focused Acinetobacter baumannii Vaccine Designed Using Reverse Vaccinology.

    Science.gov (United States)

    Ni, Zhaohui; Chen, Yan; Ong, Edison; He, Yongqun

    2017-02-21

    As one of the most influential and troublesome human pathogens, Acinetobacter baumannii ( A. baumannii ) has emerged with many multidrug-resistant strains. After collecting 33 complete A. baumannii genomes and 84 representative antibiotic resistance determinants, we used the Vaxign reverse vaccinology approach to predict classical type vaccine candidates against A. baumannii infections and new type vaccine candidates against antibiotic resistance. Our genome analysis identified 35 outer membrane or extracellular adhesins that are conserved among all 33 genomes, have no human protein homology, and have less than 2 transmembrane helices. These 35 antigens include 11 TonB dependent receptors, 8 porins, 7 efflux pump proteins, and 2 fimbrial proteins (FilF and CAM87009.1). CAM86003.1 was predicted to be an adhesin outer membrane protein absent from 3 antibiotic-sensitive strains and conserved in 21 antibiotic-resistant strains. Feasible anti-resistance vaccine candidates also include one extracellular protein (QnrA), 3 RND type outer membrane efflux pump proteins, and 3 CTX-M type β-lactamases. Among 39 β-lactamases, A. baumannii CTX-M-2, -5, and -43 enzymes are predicted as adhesins and better vaccine candidates than other β-lactamases to induce preventive immunity and enhance antibiotic treatments. This report represents the first reverse vaccinology study to systematically predict vaccine antigen candidates against antibiotic resistance for a microbial pathogen.

  15. Contribution of EmrAB efflux pumps to colistin resistance in Acinetobacter baumannii.

    Science.gov (United States)

    Lin, Ming-Feng; Lin, Yun-You; Lan, Chung-Yu

    2017-02-01

    Efflux pumps play an important role in antimicrobial resistance for Acinetobacter baumannii. However, the function of the Emr pump system and the relationship between Emr and drug resistance has not been characterized in A. baumannii. In this study, four possible groups of emr-like genes were found by searching a genome database. Among them, A1S_1772 (emrB) and A1S_1773 (emrA) were demonstrated to be co-transcribed as a single operon. Moreover, during osmotic stress, A1S_1772 showed the largest change in gene expression compared to the other emrB-like genes, and deletion of A1S_1772 (AB ΔemrB) significantly slowed cell growth in 20% sucrose. Using a phenotypic microarray analysis, the AB ΔemrB mutant was more susceptible to colistin and nafcillin, paromomycin, spiramycin, and D,L-serine hydroxmate than the wild type. The spot assay, time kill assay and minimal inhibition concentration determination also indicated that the wild type could tolerate colistin better than the AB ΔemrB mutant. Finally, the increased expression levels of all emrB-like genes, including A1S_0775, A1S_0909, A1S_1772, and A1S_1799, in colistin resistance-induced A. baumannii further supported the possible involvement of the emrB genes in A. baumannii colistin resistance. Together, the Emr pump systems in A. baumannii contribute to adaptation to osmotic stress and resistance to colistin.

  16. In vitro efficacy of doripenem against pseudomonas aeruginosa and acinetobacter baumannii by e-test

    International Nuclear Information System (INIS)

    Gilani, M.; Munir, T.; Latif, M.; Rehman, S.

    2015-01-01

    To assess the in vitro efficacy of doripenem against Pseudomonas aeruginosa and Acinetobacter baumannii using Epsilometer strips. Study Design: Cross-sectional study. Place and Duration of Study: Department of Microbiology, Army Medical College, Rawalpindi and National University of Sciences and Technology, Islamabad, from May 2014 to September 2014. Methodology: A total of 60 isolates of Acinetobacter baumannii and Pseudomonas aeruginosa collected from various clinical samples received from Military Hospital were included in the study. The specimens were inoculated onto blood, MacConkey and chocolate agars. The isolates were identified using Gram staining, motility, catalase test, oxidase test and API 20NE (Biomeriux, France). Organisms identified as Acinetobacter baumannii and Pseudomonas aeruginosa were included in the study. Bacterial suspensions equivalent to 0.5 McFarland turbidity standard of the isolates were prepared and applied on Mueller Hinton agar. Epsilometer strip was placed in the center of the plate and incubated for 18-24 hours. Minimum Inhibitory Concentration (MIC) was taken to be the point where the epsilon intersected the E-strip. MIC of all the isolates was noted. Results: For Pseudomonas aeruginosa isolates, MIC50 was 12 micro g/mL and MIC90 was 32 micro g/mL. For Acinetobacter baumannii MIC 50 and MIC90 was 32 micro g/mL. Conclusion: Doripenem is no more effective against Pseudomonas aeruginosa and Acinetobacter baumannii in our setting. (author)

  17. A multidrug resistance plasmid contains the molecular switch for type VI secretion in Acinetobacter baumannii

    Science.gov (United States)

    Weber, Brent S.; Ly, Pek Man; Irwin, Joshua N.; Pukatzki, Stefan; Feldman, Mario F.

    2015-01-01

    Infections with Acinetobacter baumannii, one of the most troublesome and least studied multidrug-resistant superbugs, are increasing at alarming rates. A. baumannii encodes a type VI secretion system (T6SS), an antibacterial apparatus of Gram-negative bacteria used to kill competitors. Expression of the T6SS varies among different strains of A. baumannii, for which the regulatory mechanisms are unknown. Here, we show that several multidrug-resistant strains of A. baumannii harbor a large, self-transmissible resistance plasmid that carries the negative regulators for T6SS. T6SS activity is silenced in plasmid-containing, antibiotic-resistant cells, while part of the population undergoes frequent plasmid loss and activation of the T6SS. This activation results in T6SS-mediated killing of competing bacteria but renders A. baumannii susceptible to antibiotics. Our data show that a plasmid that has evolved to harbor antibiotic resistance genes plays a role in the differentiation of cells specialized in the elimination of competing bacteria. PMID:26170289

  18. Clinical isolates of Acinetobacter baumannii from a Portuguese hospital: PFGE characterization, antibiotic susceptibility and biofilm-forming ability.

    Science.gov (United States)

    Duarte, Andreia; Ferreira, Susana; Almeida, Sofia; Domingues, Fernanda C

    2016-04-01

    Acinetobacter baumannii is an emerging pathogen associated with nosocomial infections that in addition has shown an increasing resistance to antibiotics. In this work the genetic diversity of A. baumannii isolates from a Portuguese hospital, their antibiotic resistance profiles and ability to form biofilms was studied. Seventy-nine clinical A. baumannii isolates were characterized by pulsed-field gel electrophoresis (PFGE) with 9 different PFGE profiles being obtained. Concerning the antimicrobial susceptibility, all A. baumannii isolates were resistant to 12 of the 17 tested antibiotics and classified as multidrug-resistant (MDR). In addition, 74.7% of the isolates showed biofilm formation ability, however no statistical significance with antibiotic resistance was observed. In contrast, urine samples isolates were more likely to form biofilms than strains isolated from other sources. Our findings highlight the high number of MDR A. baumannii isolates and the importance of the formation of biofilms as a potential virulence factor. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Identification of an Acinetobacter baumannii zinc acquisition system that facilitates resistance to calprotectin-mediated zinc sequestration.

    Directory of Open Access Journals (Sweden)

    M Indriati Hood

    Full Text Available Acinetobacter baumannii is an important nosocomial pathogen that accounts for up to 20 percent of infections in intensive care units worldwide. Furthermore, A. baumannii strains have emerged that are resistant to all available antimicrobials. These facts highlight the dire need for new therapeutic strategies to combat this growing public health threat. Given the critical role for transition metals at the pathogen-host interface, interrogating the role for these metals in A. baumannii physiology and pathogenesis could elucidate novel therapeutic strategies. Toward this end, the role for calprotectin- (CP-mediated chelation of manganese (Mn and zinc (Zn in defense against A. baumannii was investigated. These experiments revealed that CP inhibits A. baumannii growth in vitro through chelation of Mn and Zn. Consistent with these in vitro data, Imaging Mass Spectrometry revealed that CP accompanies neutrophil recruitment to the lung and accumulates at foci of infection in a murine model of A. baumannii pneumonia. CP contributes to host survival and control of bacterial replication in the lung and limits dissemination to secondary sites. Using CP as a probe identified an A. baumannii Zn acquisition system that contributes to Zn uptake, enabling this organism to resist CP-mediated metal chelation, which enhances pathogenesis. Moreover, evidence is provided that Zn uptake across the outer membrane is an energy-dependent process in A. baumannii. Finally, it is shown that Zn limitation reverses carbapenem resistance in multidrug resistant A. baumannii underscoring the clinical relevance of these findings. Taken together, these data establish Zn acquisition systems as viable therapeutic targets to combat multidrug resistant A. baumannii infections.

  20. Intranasal treatment with bacteriophage rescues mice from Acinetobacter baumannii-mediated pneumonia.

    Science.gov (United States)

    Wang, Yong; Mi, Zhiqiang; Niu, Wenkai; An, Xiaoping; Yuan, Xin; Liu, Huiying; Li, Puyuan; Liu, Yannan; Feng, Yuzhong; Huang, Yong; Zhang, Xianglilan; Zhang, Zhiyi; Fan, Hang; Peng, Fan; Tong, Yigang; Bai, Changqing

    2016-05-01

    With the emergence of drug-resistant bacteria, finding alternative agents to treat antibiotic-resistant bacterial infections is imperative. A mouse pneumonia model was developed by combining cyclophosphamide pretreatment and Acinetobacter baumannii challenge, and a lytic bacteriophage was evaluated for its therapeutic efficacy in this model by examining the survival rate, bacterial load in the lung and lung pathology. Intranasal instillation with bacteriophage rescued 100% of mice following lethal challenge with A. baumannii. Phage treatment reduced bacterial load in the lung. Microcomputed tomography indicated a reduction in lung inflammation in mice given phage. This research demonstrates that intranasal application of bacteriophage is viable, and could provide complete protection from pneumonia caused by A. baumannii.

  1. Synergistic activity of coriander oil and conventional antibiotics against Acinetobacter baumannii.

    Science.gov (United States)

    Duarte, A; Ferreira, S; Silva, F; Domingues, F C

    2012-02-15

    In this study we investigated the existence of synergistic antibacterial effect between coriander (Coriandrum sativum L.) essential oil and six different antibacterial drugs (cefoperazone, chloramphenicol, ciprofloxacin, gentamicin, tetracycline and piperacillin). The antibacterial activity of coriander oil was assessed using microdilution susceptibility testing and synergistic interaction by checkerboard assays. The association of coriander essential oil with chloramphenicol, ciprofloxacin, gentamicin and tetracycline against Acinetobacter baumannii showed in vitro effectiveness, which is an indicator of a possible synergistic interaction against two reference strains of A. baumannii (LMG 1025 and LMG 1041) (FIC index from 0.047 to 0.375). However, when tested the involvement between coriander essential oil and piperacillin or cefoperazone, the isobolograms and FIC index showed an additive interaction. The in vitro interaction could improve the antimicrobial effectiveness of ciprofloxacin, gentamicin and tetracycline and may contribute to resensitize A. baumannii to the action of chloramphenicol. Copyright © 2011 Elsevier GmbH. All rights reserved.

  2. Control of a Multi-Drug-Resistant Acinetobacter baumannii Outbreak after Orthopedics Department Relocation

    Science.gov (United States)

    Gogou, Vasiliki; Meletis, Georgios; Tsitouras, Dimosthenis

    2013-01-01

    Acinetobacter baumannii clinical isolates have the ability to survive in the hospital niche for prolonged time periods and to develop resistance against multiple antimicrobial agents. Therefore, A. baumannii has emerged as an important cause of nosocomial outbreaks worldwide, especially in critical-care environments such as intensive care units. In the present communication, we report a multi-drug-resistant A. baumannii outbreak that occurred in an orthopedics department in Greece after the admission of a patient previously hospitalized in the intensive care unit of a Greek tertiary care hospital. Despite the implementation of infection control measures, 29 patients were infected, significantly raising their hospitalization periods and treatment costs. Interestingly, the outbreak was put under control after the department’s previously programmed relocation. PMID:27694769

  3. Outbreak of resistant Acinetobacter baumannii: measures and proposal for prevention and control

    Directory of Open Access Journals (Sweden)

    Roberta Maia de Castro Romanelli

    Full Text Available Acinetobacter baumannii colonization and infection, frequent in Intensive Care Unit (ICU patients, is commonly associated with high morbimortality. Several outbreaks due to multidrug-resistant (MDR A. baumanii have been reported but few of them in Brazil. This study aimed to identify risk factors associated with colonization and infection by MDR and carbapenem-resistant A. baumannii strains isolated from patients admitted to the adult ICU at HC/UFMG. A case-control study was performed from January 2007 to June 2008. Cases were defined as patients colonized or infected by MDR/carbapenem-resistant A. baumannii, and controls were patients without MDR/carbapenem-resistant A. baumannii isolation, in a 1:2 proportion. For statistical analysis, due to changes in infection control guidelines, infection criteria and the notification process, this study was divided into two periods. During the first period analyzed, from January to December 2007, colonization or infection by MDR/carbapenem-resistant A. baumannii was associated with prior infection, invasive device utilization, prior carbapenem use and clinical severity. In the multivariate analysis, prior infection and mechanical ventilation proved to be statistically significant risk factors. Carbapenem use showed a tendency towards a statistical association. During the second study period, from January to June 2008, variables with a significant association with MDR/carbapenem-resistant A. baumannii colonization/infection were catheter utilization, carbapenem and third-generation cephalosporin use, hepatic transplantation, and clinical severity. In the multivariate analysis, only CVC use showed a statistical difference. Carbapenem and third-generation cephalosporin use displayed a tendency to be risk factors. Risk factors must be focused on infection control and prevention measures considering A. baumanni dissemination.

  4. Diversity of multi-drug resistant Acinetobacter baumannii population in a major hospital in Kuwait

    Directory of Open Access Journals (Sweden)

    Leila eVali

    2015-07-01

    Full Text Available Acinetobacter baumannii is one of the most important opportunistic pathogens that causes serious health care associated complications in critically ill patients. In the current study we report on the diversity of the clinical multi-drug resistant A. baumannii in Kuwait by molecular characterization. One hundred A. baumannii were isolated from one of the largest governmental hospitals in Kuwait. Following the identification of the isolates by molecular methods, the amplified blaOXA-51-like gene product of one isolate (KO-12 recovered from blood showed the insertion of the ISAba19 at position 379 in blaOXA-78. Of the 33 multi-drug resistant isolates, 28 (85% contained blaOXA-23, 2 (6% blaOXA-24 and 6 (18% blaPER-1 gene. We did not detect blaOXA-58, blaVIM, blaIMP, blaGES, blaVEB and blaNDM genes in any of the tested isolates. In 3 blaPER-1 positive isolates the genetic environment of blaPER-1 consisted of two copies of ISPa12 (tnpiA1 surrounding the blaPER-1 gene on a highly stable plasmid of ca. 140-kb. MLST analysis of the 33 A. baumannii isolates identified 20 different STs, of which 6 (ST-607, ST-608, ST-609, ST-610, ST-611 and ST-612 were novel. Emerging STs such as ST15 (identified for the first time in the Middle East, ST78 and ST25 were also detected. The predominant clonal complex was CC2. PFGE and MLST defined the MDR isolates as multi-clonal with diverse lineages. Our results lead us to believe that A. baumannii is diverse in clonal origins and / or is undergoing clonal expansion continuously while multiple lineages of MDR A. baumannii circulate in hospital wards simultaneously.

  5. Predictors of mortality in patients with extensively drug-resistant Acinetobacter baumannii pneumonia receiving colistin therapy.

    Science.gov (United States)

    Choi, Ik Sung; Lee, Yu Ji; Wi, Yu Mi; Kwan, Byung Soo; Jung, Kae Hwa; Hong, Woong Pyo; Kim, June Myong

    2016-08-01

    The ratio of the area under the free (unbound) concentration-time curve to minimum inhibitory concentration (fAUC/MIC) was proposed to be the pharmacokinetic/pharmacodynamic index most strongly linked to the antibacterial effect of colistin against Acinetobacter baumannii. A retrospective study of patients who received colistin to treat pneumonia caused by extensively drug-resistant (XDR) A. baumannii over a 4-year period was performed to assess the impact of the colistin MIC on mortality. A total of 227 patients were included in the analysis. The 7-day and 14-day mortality rates of patients with XDR A. baumannii pneumonia receiving colistin therapy were 15.0% and 23.8%, respectively. In the multivariate analysis, Acute Physiology and Chronic Health Evaluation (APACHE) II score, days from index culture to first dose of colistin, underlying tumour and septic shock at presentation were independent predictors of mortality in patients with XDR A. baumannii pneumonia receiving colistin therapy. In the univariate analysis, the colistin dose based on ideal body weight (IBW) correlated with patient outcome. Therefore, the use of IBW appeared to be more appropriate to calculate the colistin dosage. In addition, these results highlight the clinical significance of colistin MIC in patients with XDR A. baumannii pneumonia receiving colistin therapy. Although MICs were in the 'susceptible' range, patients infected with isolates with high colistin MICs showed a poorer clinical response rate than patients infected with isolates with low colistin MICs. Further clinical studies are needed to evaluate the roles of colistin MIC for predicting mortality in XDR A. baumannii pneumonia with a high colistin MIC. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  6. Clinical epidemiology and resistance mechanisms of carbapenem-resistant Acinetobacter baumannii, French Guiana, 2008-2014.

    Science.gov (United States)

    Mahamat, Aba; Bertrand, Xavier; Moreau, Brigitte; Hommel, Didier; Couppie, Pierre; Simonnet, Christine; Kallel, Hatem; Demar, Magalie; Djossou, Felix; Nacher, Mathieu

    2016-07-01

    This study investigated the clinical epidemiology and resistance mechanisms of Acinetobacter baumannii and characterised the clonal diversity of carbapenem-resistant A. baumannii (CRAB) during an ICU-associated outbreak at Cayenne Hospital, French Guiana. All non-duplicate A. baumannii isolates from 2008 to 2014 were tested for antibiotic susceptibility by disk diffusion. Multilocus sequence typing, pulsed-field gel electrophoresis (PFGE) and characterisation of carbapenemase-encoding genes were performed on CRAB. Of the 441 A. baumannii isolates, most were from males (54.0%) and were detected mainly from the ICU (30.8%) and medicine wards (21.8%). In the ICU, strains were mainly isolated from the respiratory tract (44.1%) and bloodstream (14.0%), whereas in medicine wards they mainly were from wound/drainage (36.5%) and bloodstream (25.0%). A. baumannii showed the greatest susceptibility to piperacillin/tazobactam (92.7%), imipenem (92.5%), colistin (95.6%) and amikacin (97.2%), being lower in the ICU and medicine wards compared with other wards. An outbreak of OXA-23-producing CRAB occurred in the 13-bed ICU in 2010. CRAB strains were more co-resistant to other antimicrobials compared with non-CRAB. Molecular genetics analysis revealed five sequence types [ST78, ST107 and ST642 and two new STs (ST830 and ST831)]. Analysis of PFGE profiles indicated cross-transmissions of CRAB within the ICU, between the ICU and one medicine ward during transfer of patients, and within that medicine ward. This study provides the first clinical and molecular data of A. baumannii from French Guiana and the Amazon basin. The ICU was the highest risk unit of this nosocomial outbreak of OXA-23-producing CRAB, which could subsequently disseminate within the hospital. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  7. Emission of extensively-drug-resistant Acinetobacter baumannii from hospital settings to the natural environment.

    Science.gov (United States)

    Seruga Music, M; Hrenovic, J; Goic-Barisic, I; Hunjak, B; Skoric, D; Ivankovic, T

    2017-08-01

    Acinetobacter baumannii is a leading emerging pathogen that is frequently recovered from patients during hospital outbreaks. The role of environmental A. baumannii reservoirs is therefore of great concern worldwide. To investigate the connection between A. baumannii causing hospital outbreaks and environmental isolates from hospital wastewater, urban sewage and river water as the final natural recipient of wastewaters. Clinical isolates from patients with hospital-acquired pneumonia and environmental isolates from water were collected during a two-month monitoring period. Recovery of A. baumannii was performed using CHROMagar Acinetobacter plates, incubated at 42°C for 48 h. Identification was performed by matrix-assisted laser desorption ionization-time of flight mass spectrometry and analyses of rpoB gene. The antibiotic resistance profiles were interpreted according to criteria given for clinical isolates of A. baumannii. The sequence types (ST) were retrieved by multi-locus sequence typing. Fourteen of 19 isolates recovered from patients, hospital wastewaters, urban sewage and river water belonged to ST-195. The remaining five isolates recovered from patients and river water were assigned to ST-1421. All isolates showed very strong relatedness and clustered into CC92, which corresponds to IC2. All isolates were non-susceptible to at least one agent in all but two or fewer antimicrobial categories, and thus were classified as 'extensively-drug-resistant' (XDR). Heteroresistance to colistin was found in two isolates from hospital wastewater. Close relatedness of clinical and environmental isolates suggests the emission of XDR A. baumannii via the untreated hospital wastewater in the natural environment. Copyright © 2017 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  8. Structural and bioinformatic characterization of an Acinetobacter baumannii type II carrier protein

    International Nuclear Information System (INIS)

    Allen, C. Leigh; Gulick, Andrew M.

    2014-01-01

    The high-resolution crystal structure of a free-standing carrier protein from Acinetobacter baumannii that belongs to a larger NRPS-containing operon, encoded by the ABBFA-003406–ABBFA-003399 genes of A. baumannii strain AB307-0294, that has been implicated in A. baumannii motility, quorum sensing and biofilm formation, is presented. Microorganisms produce a variety of natural products via secondary metabolic biosynthetic pathways. Two of these types of synthetic systems, the nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs), use large modular enzymes containing multiple catalytic domains in a single protein. These multidomain enzymes use an integrated carrier protein domain to transport the growing, covalently bound natural product to the neighboring catalytic domains for each step in the synthesis. Interestingly, some PKS and NRPS clusters contain free-standing domains that interact intermolecularly with other proteins. Being expressed outside the architecture of a multi-domain protein, these so-called type II proteins present challenges to understand the precise role they play. Additional structures of individual and multi-domain components of the NRPS enzymes will therefore provide a better understanding of the features that govern the domain interactions in these interesting enzyme systems. The high-resolution crystal structure of a free-standing carrier protein from Acinetobacter baumannii that belongs to a larger NRPS-containing operon, encoded by the ABBFA-003406–ABBFA-003399 genes of A. baumannii strain AB307-0294, that has been implicated in A. baumannii motility, quorum sensing and biofilm formation, is presented here. Comparison with the closest structural homologs of other carrier proteins identifies the requirements for a conserved glycine residue and additional important sequence and structural requirements within the regions that interact with partner proteins

  9. Structural and bioinformatic characterization of an Acinetobacter baumannii type II carrier protein

    Energy Technology Data Exchange (ETDEWEB)

    Allen, C. Leigh; Gulick, Andrew M., E-mail: gulick@hwi.buffalo.edu [University at Buffalo, Buffalo, NY 14203 (United States)

    2014-06-01

    The high-resolution crystal structure of a free-standing carrier protein from Acinetobacter baumannii that belongs to a larger NRPS-containing operon, encoded by the ABBFA-003406–ABBFA-003399 genes of A. baumannii strain AB307-0294, that has been implicated in A. baumannii motility, quorum sensing and biofilm formation, is presented. Microorganisms produce a variety of natural products via secondary metabolic biosynthetic pathways. Two of these types of synthetic systems, the nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs), use large modular enzymes containing multiple catalytic domains in a single protein. These multidomain enzymes use an integrated carrier protein domain to transport the growing, covalently bound natural product to the neighboring catalytic domains for each step in the synthesis. Interestingly, some PKS and NRPS clusters contain free-standing domains that interact intermolecularly with other proteins. Being expressed outside the architecture of a multi-domain protein, these so-called type II proteins present challenges to understand the precise role they play. Additional structures of individual and multi-domain components of the NRPS enzymes will therefore provide a better understanding of the features that govern the domain interactions in these interesting enzyme systems. The high-resolution crystal structure of a free-standing carrier protein from Acinetobacter baumannii that belongs to a larger NRPS-containing operon, encoded by the ABBFA-003406–ABBFA-003399 genes of A. baumannii strain AB307-0294, that has been implicated in A. baumannii motility, quorum sensing and biofilm formation, is presented here. Comparison with the closest structural homologs of other carrier proteins identifies the requirements for a conserved glycine residue and additional important sequence and structural requirements within the regions that interact with partner proteins.

  10. Real-Time Fluorescence Loop Mediated Isothermal Amplification for the Detection of Acinetobacter baumannii

    Science.gov (United States)

    Wang, Qinqin; Zhou, Yanbin; Li, Shaoli; Zhuo, Chao; Xu, Siqi; Huang, Lixia; Yang, Ling; Liao, Kang

    2013-01-01

    Background Detection of Acinetobacter baumannii has been relying primarily on bacterial culture that often fails to return useful results in time. Although DNA-based assays are more sensitive than bacterial culture in detecting the pathogen, the molecular results are often inconsistent and challenged by doubts on false positives, such as those due to system- and environment-derived contaminations. In addition, these molecular tools require expensive laboratory instruments. Therefore, establishing molecular tools for field use require simpler molecular platforms. The loop-mediated isothermal amplification method is relatively simple and can be improved for better use in a routine clinical bacteriology laboratory. A simple and portable device capable of performing both the amplification and detection (by fluorescence) of LAMP in the same platform has been developed in recent years. This method is referred to as real-time loop-mediated isothermal amplification. In this study, we attempted to utilize this method for rapid detection of A. baumannii. Methodology and Significant Findings Species-specific primers were designed to test the utility of this method. Clinical samples of A. baumannii were used to determine the sensitivity and specificity of this system compared to bacterial culture and a polymerase chain reaction method. All positive samples isolated from sputum were confirmed to be the species of Acinetobacter by 16S rRNA gene sequencing. The RealAmp method was found to be simpler and allowed real-time detection of DNA amplification, and could distinguish A. baumannii from Acinetobacter calcoaceticus and Acinetobacter genomic species 3. DNA was extracted by simple boiling method. Compared to bacterial culture, the sensitivity and specificity of RealAmp in detecting A. baumannii was 98.9% and 75.0%, respectively. Conclusion The RealAmp assay only requires a single unit, and the assay positivity can be verified by visual inspection. Therefore, this assay has

  11. Association of biofilm production with colonization among clinical isolates of Acinetobacter baumannii.

    Science.gov (United States)

    Ryu, Seong Yeol; Baek, Won-Ki; Kim, Hyun Ah

    2017-03-01

    The pathogen Acinetobacter baumannii is increasingly causing healthcare-associated infections worldwide, particularly in intensive care units. Biofilm formation, a factor contributing to the virulence of A. baumannii , is associated with long-term persistence in hospital environments. The present study investigates the clinical impact of biofilm production on colonization and acquisition after patient admission. Forty-nine A. baumannii isolates were obtained between August and November 2013 from Keimyung University Dongsan Medical Center, Daegu, Korea. All isolates were obtained from sputum samples of new patients infected or colonized by A. baumannii . The microtiter plate assay was used to determine biofilm formation. Twenty-four A. baumannii isolates (48%) demonstrated enhanced biofilm formation capacity than that of the standard A. baumannii strain (ATCC 19606). All isolates were resistant to carbapenem, 38 isolates (77%) were collected from patients in an intensive care unit, and 47 isolates (95%) were from patients who had been exposed to antibiotics in the previous month. The median duration of colonization was longer for biofilm-producing isolates than that of the biofilm non-biofilm producing isolates (18 days vs. 12 days, p < 0.05). Simultaneous colonization with other bacteria was more common for biofilm-producing isolates than that for the non-biofilm producing isolates. The most prevalent co-colonizing bacteria was Staphylococcus aureus . Biofilm-producing isolates seem to colonize the respiratory tract for longer durations than the non-biofilm producing isolates. During colonization, biofilm producers promote co-colonization by other bacteria, particularly S. aureus . Additional research is required to determine possible links between biofilm formation and nosocomial infection.

  12. Iron-Regulated Phospholipase C Activity Contributes to the Cytolytic Activity and Virulence of Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Steven E Fiester

    Full Text Available Acinetobacter baumannii is an opportunistic Gram-negative pathogen that causes a wide range of infections including pneumonia, septicemia, necrotizing fasciitis and severe wound and urinary tract infections. Analysis of A. baumannii representative strains grown in Chelex 100-treated medium for hemolytic activity demonstrated that this pathogen is increasingly hemolytic to sheep, human and horse erythrocytes, which interestingly contain increasing amounts of phosphatidylcholine in their membranes. Bioinformatic, genetic and functional analyses of 19 A. baumannii isolates showed that the genomes of each strain contained two phosphatidylcholine-specific phospholipase C (PC-PLC genes, which were named plc1 and plc2. Accordingly, all of these strains were significantly hemolytic to horse erythrocytes and their culture supernatants tested positive for PC-PLC activity. Further analyses showed that the transcriptional expression of plc1 and plc2 and the production of phospholipase and thus hemolytic activity increased when bacteria were cultured under iron-chelation as compared to iron-rich conditions. Testing of the A. baumannii ATCC 19606T plc1::aph-FRT and plc2::aph isogenic insertion derivatives showed that these mutants had a significantly reduced PC-PLC activity as compared to the parental strain, while testing of plc1::ermAM/plc2::aph demonstrated that this double PC-PLC isogenic mutant expressed significantly reduced cytolytic and hemolytic activity. Interestingly, only plc1 was shown to contribute significantly to A. baumannii virulence using the Galleria mellonella infection model. Taken together, our data demonstrate that both PLC1 and PLC2, which have diverged from a common ancestor, play a concerted role in hemolytic and cytolytic activities; although PLC1 seems to play a more critical role in the virulence of A. baumannii when tested in an invertebrate model. These activities would provide access to intracellular iron stores this pathogen

  13. Real-time fluorescence loop mediated isothermal amplification for the detection of Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Qinqin Wang

    Full Text Available BACKGROUND: Detection of Acinetobacter baumannii has been relying primarily on bacterial culture that often fails to return useful results in time. Although DNA-based assays are more sensitive than bacterial culture in detecting the pathogen, the molecular results are often inconsistent and challenged by doubts on false positives, such as those due to system- and environment-derived contaminations. In addition, these molecular tools require expensive laboratory instruments. Therefore, establishing molecular tools for field use require simpler molecular platforms. The loop-mediated isothermal amplification method is relatively simple and can be improved for better use in a routine clinical bacteriology laboratory. A simple and portable device capable of performing both the amplification and detection (by fluorescence of LAMP in the same platform has been developed in recent years. This method is referred to as real-time loop-mediated isothermal amplification. In this study, we attempted to utilize this method for rapid detection of A. baumannii. METHODOLOGY AND SIGNIFICANT FINDINGS: Species-specific primers were designed to test the utility of this method. Clinical samples of A. baumannii were used to determine the sensitivity and specificity of this system compared to bacterial culture and a polymerase chain reaction method. All positive samples isolated from sputum were confirmed to be the species of Acinetobacter by 16S rRNA gene sequencing. The RealAmp method was found to be simpler and allowed real-time detection of DNA amplification, and could distinguish A. baumannii from Acinetobacter calcoaceticus and Acinetobacter genomic species 3. DNA was extracted by simple boiling method. Compared to bacterial culture, the sensitivity and specificity of RealAmp in detecting A. baumannii was 98.9% and 75.0%, respectively. CONCLUSION: The RealAmp assay only requires a single unit, and the assay positivity can be verified by visual inspection

  14. Small, Enigmatic Plasmids of the Nosocomial Pathogen, Acinetobacter baumannii: Good, Bad, Who Knows?

    Directory of Open Access Journals (Sweden)

    Soo Sum Lean

    2017-08-01

    Full Text Available Acinetobacter baumannii is a Gram-negative nosocomial pathogen that has become a serious healthcare concern within a span of two decades due to its ability to rapidly acquire resistance to all classes of antimicrobial compounds. One of the key features of the A. baumannii genome is an open pan genome with a plethora of plasmids, transposons, integrons, and genomic islands, all of which play important roles in the evolution and success of this clinical pathogen, particularly in the acquisition of multidrug resistance determinants. An interesting genetic feature seen in majority of A. baumannii genomes analyzed is the presence of small plasmids that usually ranged from 2 to 10 kb in size, some of which harbor antibiotic resistance genes and homologs of plasmid mobilization genes. These plasmids are often overlooked when compared to their larger, conjugative counterparts that harbor multiple antibiotic resistance genes and transposable elements. In this mini-review, we will examine our current knowledge of these small A. baumannii plasmids and look into their genetic diversity and phylogenetic relationships. Some of these plasmids, such as the Rep-3 superfamily group and the pRAY-type, which has no recognizable replicase genes, are quite widespread among diverse A. baumannii clinical isolates worldwide, hinting at their usefulness to the lifestyle of this pathogen. Other small plasmids especially those from the Rep-1 superfamily are truly enigmatic, encoding only hypothetical proteins of unknown function, leading to the question of whether these small plasmids are “good” or “bad” to their host A. baumannii.

  15. Carbapenemase Production of Clinical Isolates Acinetobacter baumannii and Pseudomonas aeruginosa from a Bulgarian University Hospital.

    Science.gov (United States)

    Petrova, Atanaska P; Stanimirova, Irina D; Ivanov, Ivan N; Petrov, Michael M; Miteva-Katrandzhieva, Tsonka M; Grivnev, Vasil I; Kardjeva, Velichka S; Kantardzhiev, Todor V; Murdjeva, Mariana A

    2017-12-20

    Production of Bla OXA-23, OXA-24, OXA-58 and hyperexpression of OXA-51 due to ISAba1 insertion sequence are the leading causes of carbapenem resistance in Acinetobacter baumannii. The loss of OprD transmembrane protein and the overexpression of some effl ux pumps are considered to be the main factors for carbapenem resistance in Pseudomonas aeruginosa whereas metallo-enzymes' production has a secondary role. Тo examine the carbapenem resistance due to carbapenemase production among clinically signifi cant Gram-negative non-fermenters from St George University hospital, Plovdiv: A. baumannii and P. aeruginosa. Forty three A. baumannii and 43 P. aeruginosa isolates, resistant or with intermediate resistance to imipenem and/or meropenem were included in the study. They were collected from patients admitted in 14 various hospital wards between 2010 and 2014. Both phenotypic and genetic methods were used for identifi cation and antimicrobial susceptibility testing. All A. baumannii demonstrated carbapenemase production determined by a modifi ed Hodge test whereas P. aeruginosa isolates did not show this phenomenon. OXA-23 genes were determined in 97.7% (42 out of 43) of A. baumannii isolates indistinguishable from the sequence of the classical ARI-1 gene. OXA-24, OXA-58 and overexpression of OXA-51 were not registered in any of the isolates. All P. aeruginosa were negative for blaVIM and blaIMP genes. The leading cause of carbapenem resistance in A. baumannii isolates from our hospital is the carbapenemase production due to the expression of OXA- 23 gene, whereas in P. aeruginosa - the loss of transmembrane OprD protein and the effl ux pumps' hyperexpression are suspected to be the main mechanisms.

  16. Carbapenemase Production of Clinical Isolates Acinetobacter baumannii and Pseudomonas aeruginosa from a Bulgarian University Hospital

    Directory of Open Access Journals (Sweden)

    Petrova Atanaska P.

    2017-12-01

    Full Text Available Background: Production of Bla OXA-23, OXA-24, OXA-58 and hyperexpression of OXA-51 due to ISAba1 insertion sequence are the leading causes of carbapenem resistance in Acinetobacter baumannii. The loss of OprD transmembrane protein and the overexpression of some effl ux pumps are considered to be the main factors for carbapenem resistance in Pseudomonas aeruginosa whereas metallo-enzymes’ production has a secondary role. Aim: Тo examine the carbapenem resistance due to carbapenemase production among clinically signifi cant Gram-negative non-fermenters from St George University hospital, Plovdiv: A. baumannii and P. aeruginosa. Materials and methods: Forty three A. baumannii and 43 P. aeruginosa isolates, resistant or with intermediate resistance to imipenem and/or meropenem were included in the study. They were collected from patients admitted in 14 various hospital wards between 2010 and 2014. Both phenotypic and genetic methods were used for identifi cation and antimicrobial susceptibility testing. Results: All A. baumannii demonstrated carbapenemase production determined by a modifi ed Hodge test whereas P. aeruginosa isolates did not show this phenomenon. OXA-23 genes were determined in 97.7% (42 out of 43 of A. baumannii isolates indistinguishable from the sequence of the classical ARI-1 gene. OXA-24, OXA-58 and overexpression of OXA-51 were not registered in any of the isolates. All P. aeruginosa were negative for blaVIM and blaIMP genes. Conclusion: The leading cause of carbapenem resistance in A. baumannii isolates from our hospital is the carbapenemase production due to the expression of OXA- 23 gene, whereas in P. aeruginosa - the loss of transmembrane OprD protein and the effl ux pumps’ hyperexpression are suspected to be the main mechanisms.

  17. Epidemiologic and clinical impact of Acinetobacter baumannii colonization and infection: a reappraisal.

    Science.gov (United States)

    Villar, Macarena; Cano, María E; Gato, Eva; Garnacho-Montero, José; Miguel Cisneros, José; Ruíz de Alegría, Carlos; Fernández-Cuenca, Felipe; Martínez-Martínez, Luis; Vila, Jordi; Pascual, Alvaro; Tomás, María; Bou, Germán; Rodríguez-Baño, Jesús

    2014-07-01

    Acinetobacter baumannii is one of the most important antibiotic-resistant nosocomial bacteria. We investigated changes in the clinical and molecular epidemiology of A. baumannii over a 10-year period. We compared the data from 2 prospective multicenter cohort studies in Spain, one performed in 2000 (183 patients) and one in 2010 (246 patients), which included consecutive patients infected or colonized by A. baumannii. Molecular typing was performed by repetitive extragenic palindromic polymerase chain reaction (REP-PCR), pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST). The incidence density of A. baumannii colonization or infection increased significantly from 0.14 in 2000 to 0.52 in 2010 in medical services (p < 0.001). The number of non-nosocomial health care-associated cases increased from 1.2% to 14.2%, respectively (p < 0.001). Previous exposure to carbapenems increased in 2010 (16.9% in 2000 vs 27.3% in 2010, p = 0.03). The drugs most frequently used for definitive treatment of patients with infections were carbapenems in 2000 (45%) and colistin in 2010 (50.3%). There was molecular-typing evidence of an increase in the frequency of A. baumannii acquisition in non-intensive care unit wards in 2010 (7.6% in 2000 vs 19.2% in 2010, p = 0.01). By MSLT, the ST2 clonal group predominated and increased in 2010. This epidemic clonal group was more frequently resistant to imipenem and was associated with an increased risk of sepsis, although not with severe sepsis or mortality. Some significant changes were noted in the epidemiology of A. baumannii, which is increasingly affecting patients admitted to conventional wards and is also the cause of non-nosocomial health care-associated infections. Epidemic clones seem to combine antimicrobial resistance and the ability to spread, while maintaining their clinical virulence.

  18. Acinetobacter baumannii transfers the blaNDM-1 gene via outer membrane vesicles.

    Science.gov (United States)

    Chatterjee, Somdatta; Mondal, Ayan; Mitra, Shravani; Basu, Sulagna

    2017-08-01

    To investigate the transmission of the gene encoding New Delhi metallo-β-lactamase-1 ( bla NDM-1 ) through outer membrane vesicles (OMVs) released from an Acinetobacter baumannii strain (A_115). Isolation and purification of OMVs by density gradient from a carbapenem-resistant clinical strain of A. baumannii harbouring plasmid-mediated bla NDM-1 and aac(6')-Ib-cr genes was performed. DNA was purified from the OMVs and used for PCR and dot-blot analysis. Vesicles treated with DNase I and proteinase K were used to transform A. baumannii ATCC 19606 and Escherichia coli JM109 strains. MIC values for the transformants were determined, followed by PCR and restriction digestion of plasmids. PFGE was done for A_115 and transformants of ATCC 19606 and JM109. The A. baumannii strain (ST 1462) released vesicles (25-100 nm) during in vitro growth at late log phase. PCR and dot-blot analysis confirmed the presence of bla NDM-1 and aac(6')-Ib-cr genes in intravesicular DNA. bla NDM-1 and aac(6')-Ib-cr genes were transferred to both the A. baumannii ATCC 19606 and E. coli JM109 recipient cells. The transformation frequency of the purified OMVs was in the range of 10 -5 -10 -6 and gradually reduced with storage of OMVs. The sizes of the plasmids in the transformants and their restriction digestion patterns were identical to the plasmid in A_115. The transformants showed elevated MIC values of the β-lactam group of antibiotics, which confirmed the presence of a bla NDM-1 -harbouring plasmid. This is the first experimental evidence of intra- and inter-species transfer of a plasmid harbouring a bla NDM-1 gene in A. baumannii via OMVs with high transformation frequency. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Expanding mediation theory

    NARCIS (Netherlands)

    Verbeek, Peter P.C.C.

    2012-01-01

    In his article In Between Us, Yoni van den Eede expands existing theories of mediation into the realm of the social and the political, focusing on the notions of opacity and transparency. His approach is rich and promising, but two pitfalls should be avoided. First, his concept of ‘in-between’ runs

  20. Infection with Acinetobacter baumannii in an intensive care unit in the Western part of Romania.

    Science.gov (United States)

    Lăzureanu, Voichița; Poroșnicu, Mirela; Gândac, Ciprian; Moisil, Teodora; Bădițoiu, Luminița; Laza, Ruxandra; Musta, Virgil; Crișan, Alexandru; Marinescu, Adelina-Raluca

    2016-03-08

    Acinetobacter baumannii is one of the main causes of morbidity and mortality in critical condition patients. The pathogen's ability to survive under a wide range of environment conditions and to persist for long periods of time on areas represents a frequent cause of endemic infection hotbeds especially in the Intensive Care Unit. The objectives of the study are: determining the 5-year incidence of A. baumannii infection in patients admitted in the ICU which needed mechanical ventilation; the analysis of these cases regarding pathological antecedents; processing the data regarding these cases; gradual analysis of the susceptibility/resistance of isolated A. baumannii strains; observing the emergence of A. baumannii infection in patients transferred into the ICU. We have performed an observational retrospective study regarding the incidence of Acinetobacter baumannii infections in the Intensive Care Unit of the Hospital of Infectious Diseases and Pneumophtisiology "Victor Babes" Timisoara, Clinic II Infectious Diseases, during June 2011 - June 2015. We have identified a high prevalence of Acinetobacter baumannii infection, with an average period of 6 days. Bronchial suction was the most common pathological product in the study (90 % of the cases). Resistance to antimicrobials has been determined: the lowest resistance was recorded for ampicillin + sulbactam (81.1 %), and the highest resistance rate was recorded for ceftazidime and imipenem (94.6 % each). When comparing resistance to third generation cephalosporins, the difference was not statistically significant (94.6 % for ceftazidime vs. 86.5 % for cefoperazone, p = 0.117). Within the present study we were able to observe a significantly high resistance of the germ to carbapenems, with a good sensitivity to aminoglycosides, and to colistin. Only one strain of Acinetobacter baumannii was resistant to all classes of tested antibiotics. Generally, carbapenems represented the elective treatment in

  1. RNA-Mediated cis Regulation in Acinetobacter baumannii Modulates Stress-Induced Phenotypic Variation.

    Science.gov (United States)

    Ching, Carly; Gozzi, Kevin; Heinemann, Björn; Chai, Yunrong; Godoy, Veronica G

    2017-06-01

    In the nosocomial opportunistic pathogen Acinetobacter baumannii , RecA-dependent mutagenesis, which causes antibiotic resistance acquisition, is linked to the DNA damage response (DDR). Notably, unlike the Escherichia coli paradigm, recA and DDR gene expression in A. baumannii is bimodal. Namely, there is phenotypic variation upon DNA damage, which may provide a bet-hedging strategy for survival. Thus, understanding recA gene regulation is key to elucidate the yet unknown DDR regulation in A. baumannii Here, we identify a structured 5' untranslated region (UTR) in the recA transcript which serves as a cis -regulatory element. We show that a predicted stem-loop structure in this 5' UTR affects mRNA half-life and underlies bimodal gene expression and thus phenotypic variation in response to ciprofloxacin treatment. We furthermore show that the stem-loop structure of the recA 5' UTR influences intracellular RecA protein levels and, in vivo , impairing the formation of the stem-loop structure of the recA 5' UTR lowers cell survival of UV treatment and decreases rifampin resistance acquisition from DNA damage-induced mutagenesis. We hypothesize that the 5' UTR allows for stable recA transcripts during stress, including antibiotic treatment, enabling cells to maintain suitable RecA levels for survival. This innovative strategy to regulate the DDR in A. baumannii may contribute to its success as a pathogen. IMPORTANCE Acinetobacter baumannii is an opportunistic pathogen quickly gaining antibiotic resistances. Mutagenesis and antibiotic resistance acquisition are linked to the DNA damage response (DDR). However, how the DDR is regulated in A. baumannii remains unknown, since unlike most bacteria, A. baumannii does not follow the regulation of the Escherichia coli paradigm. In this study, we have started to uncover the mechanisms regulating the novel A. baumannii DDR. We have found that a cis -acting 5' UTR regulates recA transcript stability, RecA protein levels, and DNA

  2. Common phenotypic and genotypic antimicrobial resistance patterns found in a case study of multiresistant E. coli from cohabitant pets, humans, and household surfaces.

    Science.gov (United States)

    Martins, Liliana Raquel Leite; Pina, Susana Maria Rocha; Simões, Romeo Luís Rocha; de Matos, Augusto José Ferreira; Rodrigues, Pedro; da Costa, Paulo Martins Rodrigues

    2013-01-01

    The objective of the study described in this article was to characterize the antimicrobial resistance profiles among E. coli strains isolated from cohabitant pets and humans, evaluating the concurrent colonization of pets, owners, and home surfaces by bacteria carrying the same antimicrobial-resistant genes. The authors also intended to assess whether household surfaces and objects could contribute to the within-household antimicrobial-resistant gene diffusion between human and animal cohabitants. A total of 124 E. coli strains were isolated displaying 24 different phenotypic patterns with a remarkable percentage of multiresistant ones. The same resistance patterns were isolated from the dog's urine, mouth, the laundry floor, the refrigerator door, and the dog's food bowl. Some other multiresistant phenotypes, as long as resistant genes, were found repeatedly in different inhabitants and surfaces of the house. Direct, close contact between all the cohabitants and the touch of contaminated household surfaces and objects could be an explanation for these observations.

  3. Controlling endemic multidrug-resistant Acinetobacter baumannii in Intensive Care Units using antimicrobial stewardship and infection control.

    Science.gov (United States)

    Cheon, Shinhye; Kim, Mi-Ja; Yun, Seon-Jin; Moon, Jae Young; Kim, Yeon-Sook

    2016-03-01

    Nosocomial infections caused by multidrug-resistant (MDR) Acinetobacter baumannii have become public-health problem. However, few studies have evaluated the control of endemic MDR A. baumannii in Intensive Care Units (ICUs). Therefore, we investigated the effectiveness of antimicrobial stewardship and comprehensive intensified infection control measures for controlling endemic MDR A. baumannii in ICUs at a tertiary care center. Carbapenem use was strictly restricted through antimicrobial stewardship. Environmental cleaning and disinfection was performed at least 3 times per day in addition to basic infection control measures. Isolation using plastic curtains and contact precautions were applied to patients who were colonized or infected with MDR A. baumannii. The outcome was measured as the incidence density rate of hospital-onset MDR A. baumannii among patients in the ICUs. The incidence density rate of hospital-onset MDR A. baumannii decreased from 22.82 cases per 1,000 patient-days to 2.68 cases per 1,000 patient-days after the interventions were implemented (odds ratio, 0.12; 95% confidence interval, 0.03 to 0.4; p baumannii in our ICUs within 1 year.

  4. Evaluate the frequency distribution of nonadhesive virulence factors in carbapenemase-producing Acinetobacter baumannii isolated from clinical samples in Kermanshah.

    Science.gov (United States)

    Mohajeri, Parviz; Sharbati, Saba; Farahani, Abbas; Rezaei, Zhaleh

    2016-01-01

    Acinetobacter baumannii which is a Gram-negative bacterium can cause several different infections. The appearance of carbapenemase-producing A. baumannii in recent years has made the treatment process more difficult. The identification of virulence factors (VFs), such as nonadhesives in A. baumannii, helps to fight against related infections. A total of 104 samples from teaching hospitals in Kermanshah, Iran, were collected during a 24 months period (2011-2013). Sample identification was first carried out by biochemical tests, and then their susceptibility to carbapenems was determined using the Kirby-Bauer method. For confirmation of carbapenemase-producing A. baumannii, polymerase chain reaction (PCR) was done for carbapenemase-encoding genes. In addition, the frequency of nonadhesive VFs in carbapenemase-producing isolates was determined by PCR. There were 50 isolates that were identified as carbapenemase-producing A. baumannii. The PCR results showed; 40 isolates (80%) for traT, 17 isolates (34%) for cvaC, and 8 isolates (16%) for iutA, and these encode serum resistance, colicin V and aerobactin, respectively. No significant correlation was observed between these three genes. The mechanism of A. baumannii virulence has always been in question. The role of VFs has also been recognized in other Gram-negative bacteria. According to the prevalence of traT, cvaC and iutA, as nonadhesive VFs, we can suggest that they could be the main mechanism of carbapenemase-producing A. baumannii pathogenesis.

  5. New eight genes identified at the clinical multidrug-resistant Acinetobacter baumannii DMS06669 strain in a Vietnam hospital

    Directory of Open Access Journals (Sweden)

    Nguyen Si-Tuan

    2017-11-01

    Full Text Available Abstract Background Acinetobacter baumannii is an important nosocomial pathogen that can develop multidrug resistance. In this study, we characterized the genome of the A. baumannii strain DMS06669 (isolated from the sputum of a male patient with hospital-acquired pneumonia and focused on identification of genes relevant to antibiotic resistance. Methods Whole genome analysis of A. baumannii DMS06669 from hospital-acquired pneumonia patients included de novo assembly; gene prediction; functional annotation to public databases; phylogenetics tree construction and antibiotics genes identification. Results After sequencing the A. baumannii DMS06669 genome and performing quality control, de novo genome assembly was carried out, producing 24 scaffolds. Public databases were used for gene prediction and functional annotation to construct a phylogenetic tree of the DMS06669 strain with 21 other A. baumannii strains. A total of 18 possible antibiotic resistance genes, conferring resistance to eight distinct classes of antibiotics, were identified. Eight of these genes have not previously been reported to occur in A. baumannii. Conclusions Our results provide important information regarding mechanisms that may contribute to antibiotic resistance in the DMS06669 strain, and have implications for treatment of patients infected with A. baumannii.

  6. Grazing incidence beam expander

    Energy Technology Data Exchange (ETDEWEB)

    Akkapeddi, P.R.; Glenn, P.; Fuschetto, A.; Appert, Q.; Viswanathan, V.K.

    1985-01-01

    A Grazing Incidence Beam Expander (GIBE) telescope is being designed and fabricated to be used as an equivalent end mirror in a long laser resonator cavity. The design requirements for this GIBE flow down from a generic Free Electron Laser (FEL) resonator. The nature of the FEL gain volume (a thin, pencil-like, on-axis region) dictates that the output beam be very small. Such a thin beam with the high power levels characteristic of FELs would have to travel perhaps hundreds of meters or more before expanding enough to allow reflection from cooled mirrors. A GIBE, on the other hand, would allow placing these optics closer to the gain region and thus reduces the cavity lengths substantially. Results are presented relating to optical and mechanical design, alignment sensitivity analysis, radius of curvature analysis, laser cavity stability analysis of a linear stable concentric laser cavity with a GIBE. Fabrication details of the GIBE are also given.

  7. Expandable LED array interconnect

    Science.gov (United States)

    Yuan, Thomas Cheng-Hsin; Keller, Bernd

    2011-03-01

    A light emitting device that can function as an array element in an expandable array of such devices. The light emitting device comprises a substrate that has a top surface and a plurality of edges. Input and output terminals are mounted to the top surface of the substrate. Both terminals comprise a plurality of contact pads disposed proximate to the edges of the substrate, allowing for easy access to both terminals from multiple edges of the substrate. A lighting element is mounted to the top surface of the substrate. The lighting element is connected between the input and output terminals. The contact pads provide multiple access points to the terminals which allow for greater flexibility in design when the devices are used as array elements in an expandable array.

  8. Expanding the HAWC Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Johanna [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-17

    The High Altitude Water Cherenkov Gamma-Ray Observatory is expanding its current array of 300 water tanks to include 350 outrigger tanks to increase sensitivity to gamma rays above 10 TeV. This involves creating and testing hardware with which to build the new tanks, including photomultiplier tubes, high voltage supply units, and flash analog to digital converters. My responsibilities this summer included preparing, testing and calibrating that equipment.

  9. In vitro antibacterial effects of Zanthoxylum tingoassuiba root bark extracts and two of its alkaloids against multiresistant Staphylococcus aureus

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    Rafael S. Costa

    Full Text Available ABSTRACT The emergence of multiresistant strains of bacteria reinforces the need to search for new compounds able to combat resistant organisms. Medicinal plants are a great resource of bioactive substances, providing the possibility of obtaining molecules with potential antimicrobial activity. The aim of the present study is the evaluation of the antibacterial activity of extracts and alkaloids isolated from the root bark of Zanthoxylum tingoassuiba A. St.-Hil., Rutaceae, against four resistant clinical isolates and Staphylococcus aureus ATCC 25923. The dichloromethane and methanol extracts were fractionated by chromatography on silica gel, leading to the isolation of dihydrocheleryhtrine and N-methylcanadine, identified by Nuclear Magnetic Resonance spectroscopy. The antibacterial activity of the extracts and isolated compounds was evaluated by the disc diffusion method and the minimum inhibitory concentration was determined. The dichloromethane extract was the most active against all the tested strains and the two pure alkaloids were more active than the extracts. The anti-MRSA activity of the two benzophenanthridine alkaloids is demonstrated for the first time in this study. These compounds appear as potential leads for the development of new anti-MRSA compounds and could be responsible for the antibacterial activity, justifying the ethnobotanical use of Z. tingoassuiba and other species for the treatment of various infectious diseases.

  10. Photodynamic inactivation of multi-resistant bacteria (PIB) - a new approach to treat superficial infections in the 21st century.

    Science.gov (United States)

    Maisch, Tim; Hackbarth, Steffen; Regensburger, Johannes; Felgenträger, Ariane; Bäumler, Wolfgang; Landthaler, Michael; Röder, Beate

    2011-05-01

    The increasing resistance of bacteria against antibiotics is one of the most important clinical challenges of the 21(st) century. Within the gram-positive bacteria the methicillin-resistant Staphylococcus aureus and Enterococcus faecium represent the major obstacle to successful therapy. Apart from the development of new antibiotics it requires additional differently constituted approaches, like photodynamic inactivation in order to have further effective treatment options against bacteria available. Certain dyes, termed photosensitizers, are able to store the absorbed energy in long-lived electronic states upon light activation with appropriate wavelengths and thus make these states available for chemical activation of the immediate surroundings. The interaction with molecular oxygen, which leads to different, very reactive and thus cytotoxic oxygen species, is highlighted. In this review the application of the photodynamic inactivation of bacteria will be discussed regarding the possible indications in dermatology, like localized skin and wound infections or the reduction of nosocomial colonization with multi-resistant bacteria on the skin. The crucial advantage of the local application of photosensitizers followed by irradiation of the area of interest is the fact that independent of the resistance pattern of a bacterium a direct inactivation takes place similarly as with an antiseptic. In this review the physical-chemical and biological basics of photo-dynamic inactivation of bacteria (PIB) will be discussed as well as the possible dermatological indications. © The Authors • Journal compilation © Blackwell Verlag GmbH, Berlin.

  11. Studies on Acinetobacter baumannii involving multiple mechanisms of carbapenem resistance.

    Science.gov (United States)

    Sen, B; Joshi, S G

    2016-03-01

    Characterize the genetic type and resistance mechanisms of 16 carbapenem-resistant Acinetobacter baumannii (CRAB) isolates recovered between January 2010 and March 2011 from US tertiary-care hospital. A modified Hodge test demonstrated the presence of carbapenemases, but meropenem and ethylenediaminetetraacetic acid (EDTA) double-disc synergy tests and PCR for metallo-β-lactamase (MBL) genes were negative. The genes of ampC β-lactamase and efflux pump of adeABC and adeIJK were detected. The presence of oxacillinase (OXA)-like genes, blaOXA-51-like , blaOXA-23-like and blaOXA-40-like genes, and insertion sequence ISAba1 in promoter region of blaOXA-51-like and blaOXA-23-like genes were detected; and confirmed by RT-PCR analyses. The sequencing of blaOXA-51-like genes revealed two major alleles, blaOXA-66-like (blaOXA-82 ) and blaOXA-113 from 31·2 to 68·8% of isolates respectively. The blaOXA-23 and blaOXA-72 genes showed high expression and found co-harbouring blaOXA-51-like gene preceded by ISAba-1. All CRAB isolates revealed significant reduction in carO transcription, indicated downregulation of CarO porin system, a potentially independent mechanism of carbapenam resistance. Sequencing of carO gene from representative isolates showed no ISAba1 insertional inactivation. Pulsed-field gel electrophoresis revealed a clonal relationship. CRAB exhibited diversity of mechanisms of carbapenem resistance, and clonal relationship. Studies on distinct outbreaks of CRAB are alarming situation for clinicians. © 2015 The Society for Applied Microbiology.

  12. Complete genome sequence of Acinetobacter baumannii XH386 (ST208, a multi-drug resistant bacteria isolated from pediatric hospital in China

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    Youhong Fang

    2016-03-01

    Full Text Available Acinetobacter baumannii is an important bacterium that emerged as a significant nosocomial pathogen worldwide. The rise of A. baumannii was due to its multi-drug resistance (MDR, while it was difficult to treat multi-drug resistant A. baumannii with antibiotics, especially in pediatric patients for the therapeutic options with antibiotics were quite limited in pediatric patients. A. baumannii ST208 was identified as predominant sequence type of carbapenem resistant A. baumannii in the United States and China. As we knew, there was no complete genome sequence reproted for A. baumannii ST208, although several whole genome shotgun sequences had been reported. Here, we sequenced the 4087-kilobase (kb chromosome and 112-kb plasmid of A. baumannii XH386 (ST208, which was isolated from a pediatric hospital in China. The genome of A. baumannii XH386 contained 3968 protein-coding genes and 94 RNA-only encoding genes. Genomic analysis and Minimum inhibitory concentration assay showed that A. baumannii XH386 was multi-drug resistant strain, which showed resistance to most of antibiotics, except for tigecycline. The data may be accessed via the GenBank accession number CP010779 and CP010780. Keywords: Acinetobacter baumannii, Multi-drug resistance, Paediatric

  13. Screening of Herbal-Based Bioactive Extract Against Carbapenem-Resistant Strain of Acinetobacter baumannii.

    Science.gov (United States)

    Tiwari, Monalisa; Roy, Ranita; Tiwari, Vishvanath

    2016-07-01

    Acinetobacter baumannii is grouped in the ESKAPE pathogens by Infectious Disease Society of America, which is linked to high degree of morbidity, mortality, and increased costs. The high level of acquired and intrinsic resistance mechanisms of these bacteria makes it an urgent requirement to find a suitable alternative to carbapenem, a commonly prescribed drug for Acinetobacter infection. In this study, methanolic extracts of six medicinal plants were subjected to phytochemical screening and their antimicrobial activity was tested against two strains of A. baumannii (ATCC 19606, carbapenem-sensitive strain, and RS 307, carbapenem-resistant strain). Synergistic effect of the plant extracts and antibiotics was also tested. Bael or Aegle marmelos contains tannin, phenol, terpenoids, glycoside, alkaloids, coumarine, steroid, and quinones. Flowers of madar or Calotropis procera possess tannin, phenol, terpenoids, glycoside, quinone, anthraquinone, anthocyanin, coumarin, and steroid. An inhibitory growth curve was seen for both the bacterial strains when treated with A. marmelos, Curcuma longa, and leaves and flowers of C. procera. Antibiotics alone showed a small zone of inhibition, but when used with herbal extracts they exhibited larger zone of inhibition. Synergistic effect of A. marmelos and imipenem was the best against both the strains of A. baumannii. From this study, it can be concluded that extracts from A. marmelos and leaves and flowers of C. procera exhibited the most effective antibacterial activity. These herbal extracts may be used to screen the bioactive compound against the carbapenem-resistant strain of A. baumannii.

  14. Antibiotic-Resistant Acinetobacter baumannii Increasing Success Remains a Challenge as a Nosocomial Pathogen

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    Ana Maria Gonzalez-Villoria

    2016-01-01

    Full Text Available Antibiotic-resistant infectious bacteria currently imply a high risk and therefore constitute a strong challenge when treating patients in hospital settings. Characterization of these species and of particular strains is a priority for the establishment of diagnostic tests and preventive procedures. The relevance of Acinetobacter baumannii as a problematic microorganism in inpatient facilities, particularly intensive care units, has increased over time. This review aims to draw attention to (i the historical emergence of carbapenem-resistant Acinetobacter baumannii, (ii the current status of surveillance needs in Latin America, and (iii recent data suggesting that A. baumannii continues to spread and evolve in hospital settings. First, we present synopsis of the series of events leading to the discovery and precise identification of this microorganism in hospital settings. Then key events in the acquisition of antibiotic-resistant genes by this microorganism are summarized, highlighting the race between new antibiotic generation and emergence of A. baumannii resistant strains. Here we review the historical development of this species as an infectious threat, the current state of its distribution, and antibiotic resistance characteristics, and we discuss future prospects for its control.

  15. The First Outbreak Caused by Acinetobacter baumannii ST208 and ST195 in China

    Directory of Open Access Journals (Sweden)

    Junyan Qu

    2016-01-01

    Full Text Available This study aimed to analyze the clinical characteristics of patients and molecular mechanisms of the first outbreak mainly caused by sequence types (STs 208 multidrug resistant (MDR Acinetobacter baumannii in China. A total of 10 clinical samples were collected from 5 patients who were involved in the outbreak. Bacterial identification and antibiotic sensitivity tests were performed by the VITEK-2 COMPACT automated system. MICs of tigecycline for clinical isolates were determined using broth microdilution. The clonal relatedness of A. baumannii clinical isolates in our local settings was determinated by pulsed-field gel electrophoresis (PFGE and multilocus sequence typing (MLST. A total of 7 A. baumannii strains were isolated and all were MDR strains; two of them were carbapenem-nonsusceptible strains. blaOXA-23 was the only acquired carbapenemase gene in the isolates. The isolates belonged to a single clonal pulsotype determined by PFGE and two sequences types (STs determined by MLST. The isolates belonged to the globally disseminated clonal complex 92, among which ST195 and ST208 were the most common sequence types (71.43% and 28.57%. The outbreak was successfully controlled by stringent infection control measures, especially improving the hand hygiene compliance and enhancing antimicrobial stewardship. In conclusion, this is the first description of an outbreak caused mainly by A. baumannii of ST208 in China. Infection control measures should be strengthened when infection outbreaks in hospital.

  16. Meta-analysis of colistin for the treatment of Acinetobacter baumannii infection

    Science.gov (United States)

    Chen, Zhijin; Chen, Yu; Fang, Yaogao; Wang, Xiaotian; Chen, Yanqing; Qi, Qingsong; Huang, Fang; Xiao, Xungang

    2015-01-01

    Multidrug resistant among Acinetobacter baumannii infection is associated with a high mortality rate and limits the therapeutic options. The aim of this study was to assess the safety and efficacy of colistin monotherapy vs. other single antibiotic therapy AND colistin-based combination therapy (with other antibiotics) vs. colistin alone for the treatment of Acinetobacter baumannii infection. Online electronic database were searched for studies evaluating colistin with or without other antibiotics in treatment of patients with drug-resistant Acinetobacter baumannii infection. Totally, twelve studies met the inclusion criteria. For colistin-based combination therapy, six articles including 668 patients were included. Our results showed that the overall clinical response did not differ significantly between colistin-based combination therapy and monotherapy (OR = 1.37, 95% CI = 0.86–2.19, P = 0.18). This insignificance was also detected in ICU mortality, length of stay and nephrotoxicity (P > 0.05). However, the colistin-based combination therapy was shown increasing the microbiological response (OR = 2.14, 95% CI = 1.48–3.07, P colistin monotherapy, six studies involving 491 patients were analyzed. The results were in concordance with the findings of the colistin-based combination therapy group. Our results suggest that colistin may be a promising therapy as safe and efficacious as standard antibiotics for the treatment of drug-resistant Acinetobacter baumannii infection. PMID:26597507

  17. The effect of colistin resistance-associated mutations on the fitness of Acinetobacter baumannii

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    Xinli Mu

    2016-11-01

    Full Text Available Acinetobacter baumannii had emerged as an important nosocomial and opportunistic pathogen worldwide. To determine the evolutionary pathway of colistin resistance in A. baumannii and its influence on bacterial fitness, five independent colonies of A. baumannii ATCC 17978 were exposed to colistin in agar (4/5 and liquid media (1/5 with increasing and constant concentrations. Stable resistance isolates were sent for whole genome sequencing. All strains were colistin resistant after exposure to colistin. In addition to the previously reported lpxCAD and pmrAB mutations, we detected four novel putative colistin resistance genes: A1S_1983, hepA, A1S_3026, and rsfS. Lipopolysaccharide (LPS loss mutants exhibited higher fitness costs than the pmrB mutant in nutrient-rich medium. The colistin-resistant mutants showed higher inhibition ratio in the serum growth experiment than the wild type strain in 100% serum. The MIC results showed that the LPS-deficient but not the pmrB mutant altered the antibiotic resistance profile. The compensatory mutations partially or completely recovered the LPS-deficient’s fitness, suggesting that compensatory mutations played an important role in the emergence and spread of colistin resistant A. baumannii.

  18. Acinetobacter baumannii phenylacetic acid metabolism influences infection outcome through a direct effect on neutrophil chemotaxis

    Science.gov (United States)

    Bhuiyan, Md Saruar; Ellett, Felix; Murray, Gerald L.; Kostoulias, Xenia; Cerqueira, Gustavo M.; Schulze, Keith E.; Mahamad Maifiah, Mohd Hafidz; Li, Jian; Creek, Darren J.; Lieschke, Graham J.; Peleg, Anton Y.

    2016-01-01

    Innate cellular immune responses are a critical first-line defense against invading bacterial pathogens. Leukocyte migration from the bloodstream to a site of infection is mediated by chemotactic factors that are often host-derived. More recently, there has been a greater appreciation of the importance of bacterial factors driving neutrophil movement during infection. Here, we describe the development of a zebrafish infection model to study Acinetobacter baumannii pathogenesis. By using isogenic A. baumannii mutants lacking expression of virulence effector proteins, we demonstrated that bacterial drivers of disease severity are conserved between zebrafish and mammals. By using transgenic zebrafish with fluorescent phagocytes, we showed that a mutation of an established A. baumannii global virulence regulator led to marked changes in neutrophil behavior involving rapid neutrophil influx to a localized site of infection, followed by prolonged neutrophil dwelling. This neutrophilic response augmented bacterial clearance and was secondary to an impaired A. baumannii phenylacetic acid catabolism pathway, which led to accumulation of phenylacetate. Purified phenylacetate was confirmed to be a neutrophil chemoattractant. These data identify a previously unknown mechanism of bacterial-guided neutrophil chemotaxis in vivo, providing insight into the role of bacterial metabolism in host innate immune evasion. Furthermore, the work provides a potentially new therapeutic paradigm of targeting a bacterial metabolic pathway to augment host innate immune responses and attenuate disease. PMID:27506797

  19. Carbapenem resistance and mortality in patients with Acinetobacter baumannii infection: systematic review and meta-analysis.

    Science.gov (United States)

    Lemos, E V; de la Hoz, F P; Einarson, T R; McGhan, W F; Quevedo, E; Castañeda, C; Kawai, K

    2014-05-01

    Acinetobacter baumannii has emerged as a major cause of healthcare-associated infections. Controversy exists as to whether antimicrobial resistance increases the risk of mortality. We conducted a systematic review and meta-analysis to examine this association. We searched MEDLINE and EMBASE databases up to May 2013 to identify studies comparing mortality in patients with carbapenem-resistant A. baumannii (CRAB) vs. carbapenem-susceptible A. baumannii (CSAB). A random-effects model was used to pool Odds Ratios (OR). Heterogeneity was examined using I(2). We included 16 observational studies. There were 850 reported deaths (33%) among the 2546 patients. Patients with CRAB had a significantly higher risk of mortality than patients with CSAB in the pooled analysis of crude effect estimates (crude OR = 2.22; 95% CI = 1.66, 2.98), although substantial heterogeneity was evident (heterogeneity I(2) = 55%). The association remained significant in the pooled adjusted OR of 10 studies. Studies reported that patients with CRAB compared to patients with CSAB were more likely to have severe underlying illness and also to receive inappropriate empirical antimicrobial treatment, which increases the risk of mortality. Our study suggests that carbapenem resistance may increase the risk of mortality in patients with A. baumannii infection. However, cautious interpretation is required because of the residual confounding factors and inadequate sample size in most studies. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

  20. Antibiotic-Resistant Acinetobacter baumannii Increasing Success Remains a Challenge as a Nosocomial Pathogen

    Science.gov (United States)

    Gonzalez-Villoria, Ana Maria; Valverde-Garduno, Veronica

    2016-01-01

    Antibiotic-resistant infectious bacteria currently imply a high risk and therefore constitute a strong challenge when treating patients in hospital settings. Characterization of these species and of particular strains is a priority for the establishment of diagnostic tests and preventive procedures. The relevance of Acinetobacter baumannii as a problematic microorganism in inpatient facilities, particularly intensive care units, has increased over time. This review aims to draw attention to (i) the historical emergence of carbapenem-resistant Acinetobacter baumannii, (ii) the current status of surveillance needs in Latin America, and (iii) recent data suggesting that A. baumannii continues to spread and evolve in hospital settings. First, we present synopsis of the series of events leading to the discovery and precise identification of this microorganism in hospital settings. Then key events in the acquisition of antibiotic-resistant genes by this microorganism are summarized, highlighting the race between new antibiotic generation and emergence of A. baumannii resistant strains. Here we review the historical development of this species as an infectious threat, the current state of its distribution, and antibiotic resistance characteristics, and we discuss future prospects for its control. PMID:26966582

  1. Evaluation of antibacterial effect of Myrtus communis against Acinetobacter baumannii clinical strains

    Directory of Open Access Journals (Sweden)

    Venous Akhavan

    2016-09-01

    Full Text Available Because of inappropriate use of antibiotics and prevalence of resistant bacteria, there is urgent need for antibacterial drugs that have fewer side effects than antibiotics. Myrtus communis is a medicinal plant which had many uses in traditional medicine. In this study, ethanol leave extract of this plant is tested on Acinetobacter baumannii. In the case of antimicrobial evaluation of plants, one of the effecting factors on effectiveness of the microbial inhibition is extraction techniques. In the presents study, the antibacterial activity of the Ethanol, Methanol, and Ethyl acetate extracts of M. communis plant was evaluated at seven different concentrations by broth microdilution method. The results of this study showed that the antimicrobial effect of M. communis extract is concentration dependent. Different extracts were obtained by the maceration method. Extracts of the plant exhibited antibacterial activity at varied levels against A. baumannii. Obtained results from our antibacterial experiments showed that all extracts have anti-bacterial activity against tested bacterial isolates According to the results, the ethyl acetate extracted fraction showed the highest level of activity at a MIC 400 mg/ml for A. baumannii. The results of this study indicate that, different extracts had growth inhibitory effect on A. baumannii. Therefore this plant has the potential to be evaluated as an alternative or adjunct to antibiotics to treat Acinetobacter infections.

  2. Treatment Options for Carbapenem-Resistant and Extensively Drug-Resistant Acinetobacter baumannii Infections

    Science.gov (United States)

    Viehman, J. Alexander; Nguyen, Minh-Hong; Doi, Yohei

    2014-01-01

    Acinetobacter baumannii is a leading cause of healthcare-associated infections worldwide. Due to various intrinsic and acquired mechanisms of resistance, most β-lactam agents are not effective against many strains, and carbapenems have played an important role in therapy. Recent trends show many infections are caused by carbapenem-resistant, or even extensively drug-resistant (XDR) strains, for which effective therapy is not well established. Evidence to date suggests that colistin constitutes the backbone of therapy, but the unique pharmacokinetic properties of colistin have led many to suggest the use of combination antimicrobial therapy. However, the combination of agents and dosing regimens that delivers the best clinical efficacy while minimizing toxicity is yet to be defined. Carbapenems, sulbactam, rifampin and tigecycline have been the most studied in the context of combination therapy. Most data regarding therapy for invasive, resistant A. baumannii infections come from uncontrolled case series and retrospective analyses, though some clinical trials have been completed and others are underway. Early institution of appropriate antimicrobial therapy is shown to consistently improve survival of patients with carbapenem-resistant and XDR A. baumannii infection, but the choice of empiric therapy in these infections remains an open question. This review summarizes the most current knowledge regarding the epidemiology, mechanisms of resistance, and treatment considerations of carbapenem-resistant and XDR A. baumannii. PMID:25091170

  3. A medically relevant capsular polysaccharide in Acinetobacter baumannii is a potential vaccine candidate.

    Science.gov (United States)

    Yang, Feng-Ling; Lou, Tze-Chi; Kuo, Shu-Chen; Wu, Wan-Ling; Chern, Jeffy; Lee, Yi-Tzu; Chen, Shui-Tsung; Zou, Wei; Lin, Nien-Tsung; Wu, Shih-Hsiung

    2017-03-07

    Concerns of Acinetobacter baumannii infection have increased due to the emergence of multi-drug resistance. In the present study, we determined the capsular polysaccharide (CPS) structure of A. baumannii SK44, a clinical isolate from Taiwan, to consist of pentasaccharide repeats. We found that CPS-induced antibody provided 55% protection against challenge in an animal model. The CPS-specific antibody reacted with the surface components of about 62% clinical isolates (342/554 strains) from cross-sectional and longitudinal studies by dot-immunoassay. Pulsed-field gel electrophoresis of positive strains showed the antibody covered different clonalites of A. baumannii clinical isolates. Meanwhile, using the CPS antibody as a probe, we found a number of outer membrane proteins bound to the antibody, including OmpA/motB, TonB-dependent receptor, and Omp38, indicating their association with CPS. These results might lead to the use of the capsular polysaccharide as a vaccine to prevent A. baumannii infection. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Emergence of Oxacillinases in Environmental Carbapenem-Resistant Acinetobacter baumannii Associated with Clinical Isolates.

    Science.gov (United States)

    Goic-Barisic, Ivana; Hrenovic, Jasna; Kovacic, Ana; Musić, Martina Šeruga

    2016-10-01

    Six carbapenem-resistant isolates of Acinetobacter baumannii were recovered from untreated and treated municipal wastewater of the capital city of Zagreb, Croatia. Molecular identification of environmental isolates of A. baumannii was performed by amplification, sequencing, and phylogenetic analyses of rpoB gene. The presence of bla OXA genes encoding OXA-type carbapenemases (OXA-51-like, OXA-23, and OXA-40-like) was confirmed by multiplex PCR and sequencing. Phylogenetic analyses corroborated the affiliation of detected bla OXA genes to three different clusters and showed association of environmental OXAs with those described from clinical isolates. This result suggests that isolates recovered from municipal wastewater are most probably of clinical origin. Furthermore, the presence of OXA-40-like (OXA-72) in an environmental A. baumannii isolate is reported for the first time. Persistence of A. baumannii harboring the clinically important OXAs in the wastewater treatment process poses a potentially significant source for horizontal gene transfer and implications for wider spread of antibiotic resistance genes.

  5. Acinetobacter baumannii phenylacetic acid metabolism influences infection outcome through a direct effect on neutrophil chemotaxis.

    Science.gov (United States)

    Bhuiyan, Md Saruar; Ellett, Felix; Murray, Gerald L; Kostoulias, Xenia; Cerqueira, Gustavo M; Schulze, Keith E; Mahamad Maifiah, Mohd Hafidz; Li, Jian; Creek, Darren J; Lieschke, Graham J; Peleg, Anton Y

    2016-08-23

    Innate cellular immune responses are a critical first-line defense against invading bacterial pathogens. Leukocyte migration from the bloodstream to a site of infection is mediated by chemotactic factors that are often host-derived. More recently, there has been a greater appreciation of the importance of bacterial factors driving neutrophil movement during infection. Here, we describe the development of a zebrafish infection model to study Acinetobacter baumannii pathogenesis. By using isogenic A. baumannii mutants lacking expression of virulence effector proteins, we demonstrated that bacterial drivers of disease severity are conserved between zebrafish and mammals. By using transgenic zebrafish with fluorescent phagocytes, we showed that a mutation of an established A. baumannii global virulence regulator led to marked changes in neutrophil behavior involving rapid neutrophil influx to a localized site of infection, followed by prolonged neutrophil dwelling. This neutrophilic response augmented bacterial clearance and was secondary to an impaired A. baumannii phenylacetic acid catabolism pathway, which led to accumulation of phenylacetate. Purified phenylacetate was confirmed to be a neutrophil chemoattractant. These data identify a previously unknown mechanism of bacterial-guided neutrophil chemotaxis in vivo, providing insight into the role of bacterial metabolism in host innate immune evasion. Furthermore, the work provides a potentially new therapeutic paradigm of targeting a bacterial metabolic pathway to augment host innate immune responses and attenuate disease.

  6. The Acinetobacter baumannii Oxymoron: Commensal Hospital Dweller Turned Pan-Drug-Resistant Menace

    Science.gov (United States)

    Roca, Ignasi; Espinal, Paula; Vila-Farrés, Xavier; Vila, Jordi

    2012-01-01

    During the past few decades Acinetobacter baumannii has evolved from being a commensal dweller of health-care facilities to constitute one of the most annoying pathogens responsible for hospitalary outbreaks and it is currently considered one of the most important nosocomial pathogens. In a prevalence study of infections in intensive care units conducted among 75 countries of the five continents, this microorganism was found to be the fifth most common pathogen. Two main features contribute to the success of A. baumannii: (i) A. baumannii exhibits an outstanding ability to accumulate a great variety of resistance mechanisms acquired by different mechanisms, either mutations or acquisition of genetic elements such as plasmids, integrons, transposons, or resistant islands, making this microorganism multi- or pan-drug-resistant and (ii) The ability to survive in the environment during prolonged periods of time which, combined with its innate resistance to desiccation and disinfectants, makes A. baumannii almost impossible to eradicate from the clinical setting. In addition, its ability to produce biofilm greatly contributes to both persistence and resistance. In this review, the pathogenesis of the infections caused by this microorganism as well as the molecular bases of antibacterial resistance and clinical aspects such as treatment and potential future therapeutic strategies are discussed in depth. PMID:22536199

  7. Isolation and characterization of Acinetobacter baumannii recovered from Campylobacter selective medium.

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    Dinesh M Fernando

    2016-11-01

    Full Text Available Acinetobacter baumannii, a Gram-negative opportunistic pathogen, is known to cause multidrug resistant infections. This organism has primarily been isolated from clinical environments and its environmental reservoirs remain largely unknown. In the present study, we recovered seven isolates of A. baumannii growing under conditions selective for Campylobacter spp. (microaerophilic at 42 oC and in the presence of antibiotics from dairy cattle manure storage tank or surface water impacted by livestock effluents. Antibiotic susceptibility tests revealed that all of these isolates were less susceptible to at least two different clinically relevant antibiotics, compared to the type strain A. baumannii ATCC17978. Expression of resistance-nodulation-division efflux pumps, an important mechanism of intrinsic resistance in these organisms, was analyzed and adeB was found to be overexpressed in one and adeJ was overexpressed in three isolates. Comparison of these isolates using genomic DNA Macro-Restriction Fragment Pattern Analysis (MRFPA revealed relatively low relatedness among themselves or with some of the clinical isolates from previous studies. This study suggests that A. baumannii isolates are capable of growing under selective conditions for Campylobacter spp. and that this organism can be present in manure and water.

  8. Acinetobacter baumannii in critically ill patients: Molecular epidemiology, clinical features and predictors of mortality.

    Science.gov (United States)

    Garnacho-Montero, José; Gutiérrez-Pizarraya, Antonio; Díaz-Martín, Ana; Cisneros-Herreros, José Miguel; Cano, María Eugenia; Gato, Eva; Ruiz de Alegría, Carlos; Fernández-Cuenca, Felipe; Vila, Jordi; Martínez-Martínez, Luis; Tomás-Carmona, M Del Mar; Pascual, Álvaro; Bou, Germán; Pachón-Diaz, Jerónimo; Rodríguez-Baño, Jesús

    2016-11-01

    The main aim of this study was to assess changes in the epidemiology and clinical presentation of Acinetobacter baumannii over a 10-year period, as well as risk factors of mortality in infected patients. Prospective, multicentre, hospital-based cohort studies including critically ill patients with A. baumannii isolated from any clinical sample were included. These were divided into a first period ("2000 study") (one month), and a second period ("2010 study") (two months). Molecular typing was performed by REP-PCR, PFGE and MSLT. The primary endpoint was 30-day mortality. In 2000 and 2010, 103 and 108 patients were included, and the incidence of A. baumannii colonization/infection in the ICU decreased in 2010 (1.23 vs. 4.35 cases/1000 patient-days; pbaumannii infection, the multivariate analysis identified appropriate antimicrobial therapy and ST79 clonal group as protective factors for mortality. At 10 years of the first analysis, some variations have been observed in the epidemiology of A. baumannii in the ICU, with no changes in mortality. Epidemic ST79 clone seems to be associated with a better prognosis and adequate treatment is crucial in terms of survival. Copyright © 2015 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  9. CipA of Acinetobacter baumannii Is a Novel Plasminogen Binding and Complement Inhibitory Protein.

    Science.gov (United States)

    Koenigs, Arno; Stahl, Julia; Averhoff, Beate; Göttig, Stephan; Wichelhaus, Thomas A; Wallich, Reinhard; Zipfel, Peter F; Kraiczy, Peter

    2016-05-01

    Acinetobacter baumannii is an emerging opportunistic pathogen, responsible for up to 10% of gram-negative, nosocomial infections. The global increase of multidrug-resistant and pan-resistant Acinetobacter isolates presents clinicians with formidable challenges. To establish a persistent infection,A. baumannii must overcome the detrimental effects of complement as the first line of defense against invading microorganisms. However, the immune evasion principles underlying serum resistance inA. baumannii remain elusive. Here, we identified a novel plasminogen-binding protein, termed CipA. Bound plasminogen, upon conversion to active plasmin, degraded fibrinogen and complement C3b and contributed to serum resistance. Furthermore, CipA directly inhibited the alternative pathway of complement in vitro, irrespective of its ability to bind plasminogen. A CipA-deficient mutant was efficiently killed by human serum and showed a defect in the penetration of endothelial monolayers, demonstrating that CipA is a novel multifunctional protein that contributes to the pathogenesis ofA. baumannii. © The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  10. Differential Role of the T6SS in Acinetobacter baumannii Virulence

    Science.gov (United States)

    Foucault-Grunenwald, Marie-Laure; Borges, Vitor; Charpentier, Xavier; Limansky, Adriana S.; Gomes, João Paulo; Viale, Alejandro M.; Salcedo, Suzana P.

    2015-01-01

    Gram-negative bacteria, such as Acinetobacter baumannii, are an increasing burden in hospitals worldwide with an alarming spread of multi-drug resistant (MDR) strains. Herein, we compared a type strain (ATCC17978), a non-clinical isolate (DSM30011) and MDR strains of A. baumannii implicated in hospital outbreaks (Ab242, Ab244 and Ab825), revealing distinct patterns of type VI secretion system (T6SS) functionality. The T6SS genomic locus is present and was actively transcribed in all of the above strains. However, only the A. baumannii DSM30011 strain was capable of killing Escherichia coli in a T6SS-dependent manner, unlike the clinical isolates, which failed to display an active T6SS in vitro. In addition, DSM30011 was able to outcompete ATCC17978 as well as Pseudomonas aeruginosa and Klebsiella pneumoniae, bacterial pathogens relevant in mixed nosocomial infections. Finally, we found that the T6SS of DSM30011 is required for host colonization of the model organism Galleria mellonella suggesting that this system could play an important role in A. baumannii virulence in a strain-specific manner. PMID:26401654

  11. Molecular epidemiology of Acinetobacter baumannii in central intensive care unit in Kosova teaching hospital

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    Lul Raka

    Full Text Available Infections caused by bacteria of genus Acinetobacter pose a significant health care challenge worldwide. Information on molecular epidemiological investigation of outbreaks caused by Acinetobacter species in Kosova is lacking. The present investigation was carried out to enlight molecular epidemiology of Acinetobacterbaumannii in the Central Intensive Care Unit (CICU of a University hospital in Kosova using pulse field gel electrophoresis (PFGE. During March - July 2006, A. baumannii was isolated from 30 patients, of whom 22 were infected and 8 were colonised. Twenty patients had ventilator-associated pneumonia, one patient had meningitis, and two had coinfection with bloodstream infection and surgical site infection. The most common diagnoses upon admission to the ICU were politrauma and cerebral hemorrhage. Bacterial isolates were most frequently recovered from endotracheal aspirate (86.7%. First isolation occurred, on average, on day 8 following admission (range 1-26 days. Genotype analysis of A. baumannii isolates identified nine distinct PFGE patterns, with predominance of PFGE clone E represented by isolates from 9 patients. Eight strains were resistant to carbapenems. The genetic relatedness of Acinetobacter baumannii was high, indicating cross-transmission within the ICU setting. These results emphasize the need for measures to prevent nosocomial transmission of A. baumannii in ICU.

  12. The Immune Response against Acinetobacter baumannii, an Emerging Pathogen in Nosocomial Infections

    Science.gov (United States)

    García-Patiño, María Guadalupe; García-Contreras, Rodolfo; Licona-Limón, Paula

    2017-01-01

    Acinetobacter baumannii is the etiologic agent of a wide range of nosocomial infections, including pneumonia, bacteremia, and skin infections. Over the last 45 years, an alarming increase in the antibiotic resistance of this opportunistic microorganism has been reported, a situation that hinders effective treatments. In order to develop effective therapies against A. baumannii it is crucial to understand the basis of host–bacterium interactions, especially those concerning the immune response of the host. Different innate immune cells such as monocytes, macrophages, dendritic cells, and natural killer cells have been identified as important effectors in the defense against A. baumannii; among them, neutrophils represent a key immune cell indispensable for the control of the infection. Several immune strategies to combat A. baumannii have been identified such as recognition of the bacteria by immune cells through pattern recognition receptors, specifically toll-like receptors, which trigger bactericidal mechanisms including oxidative burst and cytokine and chemokine production to amplify the immune response against the pathogen. However, a complete picture of the protective immune strategies activated by this bacteria and its potential therapeutic use remains to be determined and explored. PMID:28446911

  13. Insights on the Horizontal Gene Transfer of Carbapenemase Determinants in the Opportunistic Pathogen Acinetobacter baumannii

    Science.gov (United States)

    Da Silva, Gabriela Jorge; Domingues, Sara

    2016-01-01

    Horizontal gene transfer (HGT) is a driving force to the evolution of bacteria. The fast emergence of antimicrobial resistance reflects the ability of genetic adaptation of pathogens. Acinetobacter baumannii has emerged in the last few decades as an important opportunistic nosocomial pathogen, in part due to its high capacity of acquiring resistance to diverse antibiotic families, including to the so-called last line drugs such as carbapenems. The rampant selective pressure and genetic exchange of resistance genes hinder the effective treatment of resistant infections. A. baumannii uses all the resistance mechanisms to survive against carbapenems but production of carbapenemases are the major mechanism, which may act in synergy with others. A. baumannii appears to use all the mechanisms of gene dissemination. Beyond conjugation, the mostly reported recent studies point to natural transformation, transduction and outer membrane vesicles-mediated transfer as mechanisms that may play a role in carbapenemase determinants spread. Understanding the genetic mobilization of carbapenemase genes is paramount in preventing their dissemination. Here we review the carbapenemases found in A. baumannii and present an overview of the current knowledge of contributions of the various HGT mechanisms to the molecular epidemiology of carbapenem resistance in this relevant opportunistic pathogen. PMID:27681923

  14. Differential Role of the T6SS in Acinetobacter baumannii Virulence.

    Directory of Open Access Journals (Sweden)

    Guillermo D Repizo

    Full Text Available Gram-negative bacteria, such as Acinetobacter baumannii, are an increasing burden in hospitals worldwide with an alarming spread of multi-drug resistant (MDR strains. Herein, we compared a type strain (ATCC17978, a non-clinical isolate (DSM30011 and MDR strains of A. baumannii implicated in hospital outbreaks (Ab242, Ab244 and Ab825, revealing distinct patterns of type VI secretion system (T6SS functionality. The T6SS genomic locus is present and was actively transcribed in all of the above strains. However, only the A. baumannii DSM30011 strain was capable of killing Escherichia coli in a T6SS-dependent manner, unlike the clinical isolates, which failed to display an active T6SS in vitro. In addition, DSM30011 was able to outcompete ATCC17978 as well as Pseudomonas aeruginosa and Klebsiella pneumoniae, bacterial pathogens relevant in mixed nosocomial infections. Finally, we found that the T6SS of DSM30011 is required for host colonization of the model organism Galleria mellonella suggesting that this system could play an important role in A. baumannii virulence in a strain-specific manner.

  15. The Immune Response againstAcinetobacter baumannii, an Emerging Pathogen in Nosocomial Infections.

    Science.gov (United States)

    García-Patiño, María Guadalupe; García-Contreras, Rodolfo; Licona-Limón, Paula

    2017-01-01

    Acinetobacter baumannii is the etiologic agent of a wide range of nosocomial infections, including pneumonia, bacteremia, and skin infections. Over the last 45 years, an alarming increase in the antibiotic resistance of this opportunistic microorganism has been reported, a situation that hinders effective treatments. In order to develop effective therapies against A. baumannii it is crucial to understand the basis of host-bacterium interactions, especially those concerning the immune response of the host. Different innate immune cells such as monocytes, macrophages, dendritic cells, and natural killer cells have been identified as important effectors in the defense against A. baumannii ; among them, neutrophils represent a key immune cell indispensable for the control of the infection. Several immune strategies to combat A. baumannii have been identified such as recognition of the bacteria by immune cells through pattern recognition receptors, specifically toll-like receptors, which trigger bactericidal mechanisms including oxidative burst and cytokine and chemokine production to amplify the immune response against the pathogen. However, a complete picture of the protective immune strategies activated by this bacteria and its potential therapeutic use remains to be determined and explored.

  16. Isolation and Characterization of a Virulent Bacteriophage AB1 of Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Jia Shiru

    2010-04-01

    Full Text Available Abstract Background Acinetobacter baumannii is an emerging nosocomial pathogen worldwide with increasing prevalence of multi-drug and pan-drug resistance. A. baumannii exists widely in natural environment, especially in health care settings, and has been shown difficult to be eradicated. Bacteriophages are often considered alternative agent for controlling bacterial infection and contamination. In this study, we described the isolation and characterization of one virulent bacteriophage AB1 capable of specifically infecting A. baumannii. Results A virulent bacteriophage AB1, specific for infecting a clinical strain A. baumannii KD311, was first isolated from marine sediment sample. Restriction analysis indicated that phage AB1 was a dsDNA virus with an approximate genome size of 45.2 kb to 46.9 kb. Transmission electron microscopy showed that phage AB1 had an icosahedral head with a non-contractile tail and collar or whisker structures, and might be tentatively classified as a member of the Siphoviridae family. Proteomic pattern of phage AB1, generated by SDS-PAGE using purified phage particles, revealed five major bands and six minor bands with molecular weight ranging from 14 to 80 kilo-dalton. Also determined was the adsorption rate of phage AB1 to the host bacterium, which was significantly enhanced by addition of 10 mM CaCl2. In a single step growth test, phage AB1 was shown having a latent period of 18 minutes and a burst size of 409. Moreover, pH and thermal stability of phage AB1 were also investigated. At the optimal pH 6.0, 73.2% of phages survived after 60 min incubation at 50°C. When phage AB1 was used to infect four additional clinical isolates of A. baumannii, one clinical isolate of Stenotrophomonas maltophilia, and Pseudomonas aeruginosa lab strains PAK and PAO1, none of the tested strains was found susceptible, indicating a relatively narrow host range for phage AB1. Conclusion Phage AB1 was capable of eliciting efficient lysis

  17. Substrate specificities and efflux efficiencies of RND efflux pumps of Acinetobacter baumannii.

    Science.gov (United States)

    Leus, Inga V; Weeks, Jon W; Bonifay, Vincent; Smith, Lauren; Richardson, Sophie; Zgurskaya, Helen I

    2018-04-16

    Antibiotic resistant Acinetobacter baumannii causes infections that are extremely difficult to treat. A significant role in these resistance profiles is attributed to multidrug efflux pumps, especially those belonging to Resistance-Nodulation-cell Division (RND) superfamily of transporters. In this study, we analyzed functions and properties of RND efflux pumps in A. baumannii ATCC 17978. This strain is susceptible to antibiotics and does not contain mutations that are commonly selected upon exposure to high concentrations of antibiotics. We constructed derivatives of ATCC 17978 lacking chromosomally encoded RND pumps and complemented these strains by the plasmid-borne genes. We analyzed the substrate selectivities and efficiencies of the individual pumps in the context of native outer membranes and their hyperporinated variants. Our results show that inactivation of AdeIJK provides the strongest potentiation of antibiotic activities, whereas inactivation of AdeFGH triggers the overexpression of AdeAB. The plasmid-borne overproduction complements the hypersusceptible phenotypes of the efflux deletion mutants to the levels of the parental ATCC 17978. Only a few antibiotics strongly benefitted from the overproduction of efflux pumps and antibacterial activities of some of those depended on the synergistic interaction with the low permeability barrier of the outer membrane. Either overproduction or inactivation of efflux pumps change dramatically the lipidome of ATCC 17978. We conclude that efflux pumps of A. baumannii are tightly integrated into physiology of this bacterium and that clinical levels of antibiotic resistance in A. baumannii isolates are unlikely to be reached solely due to overproduction of RND efflux pumps. Importance RND-type efflux pumps are important contributors in development of clinical antibiotic resistance in A. baumannii However, their specific roles and the extent of contribution to antibiotic resistance remain unclear. We analyzed

  18. Evaluation of the ability of Acinetobacter baumannii to form biofilms on six different biomedical relevant surfaces.

    Science.gov (United States)

    Greene, C; Wu, J; Rickard, A H; Xi, C

    2016-10-01

    The human opportunistic pathogen, Acinetobacter baumannii, has the propensity to form biofilms and frequently cause medical device-related infections in hospitals. However, the physio-chemical properties of medical surfaces, in addition to bacterial surface properties, will affect colonization and biofilm development. The objective of this study was to compare the ability of A. baumannii to form biofilms on six different materials common to the hospital environment: glass, porcelain, stainless steel, rubber, polycarbonate plastic and polypropylene plastic. Biofilms were developed on material coupons in a CDC biofilm reactor. Biofilms were visualized and quantified using fluorescent staining and imaged using confocal laser scanning microscopy (CLSM) and by direct viable cell counts. Image analysis of CLSM stacks indicated that the mean biomass values for biofilms grown on glass, rubber, porcelain, polypropylene, stainless steel and polycarbonate were 0·04, 0·26, 0·62, 1·00, 2·08 and 2·70 μm(3) /μm(2) respectively. Polycarbonate developed statistically more biofilm mass than glass, rubber, porcelain and polypropylene. Viable cell counts data were in agreement with the CLSM-derived data. In conclusion, polycarbonate was the most accommodating surface for A. baumannii ATCC 17978 to form biofilms while glass was least favourable. Alternatives to polycarbonate for use in medical and dental devices may need to be considered. In the hospital environment, Acinetobacter baumannii is one of the most persistent and difficult to control opportunistic pathogens. The persistence of A. baumannii is due, in part, to its ability to colonize surfaces and form biofilms. This study demonstrates that A. baumannii can form biofilms on a variety of different surfaces and develops substantial biofilms on polycarbonate - a thermoplastic material that is often used in the construction of medical devices. The findings highlight the need to further study the in

  19. Antibiotic Resistance and Carriage Integron Classes in Clinical Isolates of Acinetobacter Baumannii from Isfahan Hospitals, Iran

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    Fahimeh Nourbakhsh

    2017-01-01

    Full Text Available Background Acinetobacter baumannii is a significant nosocomial pathogen around the world, especially in the intensive care unit that most A. baumannii infections are caused by the outbreak strains. Objectives This study has been performed in Acinetobacter baumannii isolates, aimed to detect integron classes I, II, III and molecular typing of A. baumannii genes. Methods In this Cross-sectional study, Acinetobacter baumannii isolated from 150 patients in Isfahan hospitals then antibiotic resistance pattern was determined by disk diffusion method (Kirby Bauer. The presence of genes coding in antibiotic resistance and integrons class I, II, III were analyzed by using of M-PCR method. The data were analyzed by Chi-square, Fischer’s test and SPSS statistical software version 16. Results Antibiotic resistance pattern for Acinetobacter baumannii show that the high resistance was for ciprofloxacin with frequency of 98.3%, ceftazidime with 89.4%, and tetracycline with frequency of 87.3%. The most sensitive antibiotics were chloramphenicol, and nitrofurantoin with frequency of 3.5% and 3.2% resistance. The detection of dfrA1 (63.7%, sul1 (68.6%, aac (3-IV (54.4%, tet (B (22.4%, tet (A (78.3%, aadA1 (15.4%, CITM (17. %, vim (12.2%, Qnr (17.1%, blaSHV (19.8%, sim (7.8%, Oxa-24-like (13.2%, Oxa-51-like (11.9%, Oxa-58-like (39.4%, Oxa-23-like (12.6%, imp (9.2%, cmlA (19% and cat1 (8.6% were respectively reported too. Also in this study Frequency of integrons class 1, 2, 3 were (100%, (28%, (6.6% respectively. Conclusions High prevalence of integrons among Acinetobater baumannii isolated from Isfahan hospitals indicate the importance role of integron classes in multidrug resistance. Considering the increasing pattern of MDR infections is one of the important issues of treatment which can be effective strategy for curing.

  20. Expanding Your Horizon 2015

    CERN Multimedia

    Kaltenhauser, Kristin

    2015-01-01

    Expanding your horizons is a bi-annual “Science Day” for girls aged 11 to 14, held at the University of Geneva on 14 November. The girls had the opportunity to take part in hands-on workshops held by local professional women in the field of science, mathematics, engineering and technology. For the fourth time, CERN was part of this event, offering three workshops as well as a booth at the Discovery Fair, including Higgnite, an interactive visualization of the Higgs Field.

  1. The expanding universe

    CERN Document Server

    Lew, Kristi

    2011-01-01

    People have always been fascinated with the stars above and the universe that contains them. Over the years, astronomers have developed numerous theories to explain how the universe began, how it works, and what its ultimate fate will be. But all of the scientists' questions are far from answered. The Expanding Universe goes beyond the creation of the universe to explain how scientists think the universe works, grows, and changes, including what great thinkers Isaac Newton and Albert Einstein had to say about its fate. Readers will also learn about how researchers are slowly shedding light on

  2. Dissemination of multidrug resistant Acinetobacter baumannii in various hospitals of Antananarivo Madagascar

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    Carod Jean-François

    2010-06-01

    Full Text Available Abstract This study reports the dissemination of multidrug-resistant (MDR OXA-23-producing Acinetobacter baumannii clones in hospitals in Antananarivo, Madagascar. A total of 53 carbapenem-resistant A. baumannii isolates were obtained from September 2006 to March 2009 in five hospitals. These resistant strains represent 44% of all A. baumannii isolates. The double disk synergy test was performed to screen for production of metallo-beta-lactamases. Polymerase chain reaction (PCR and DNA sequencing were performed for the detection of bla(AmpC, bla(OXA-51,bla(OXA-23, bla(OXA-24, bla(IMP, bla(VIM. The presence of the insertion sequence ISAba1 relative to blaOXA-23 and blaOXA-51 was assessed by PCR. Isolates were typed by Rep-PCR. All the isolates were MDR and produced the OXA-23 carbapenemase, which was confirmed by sequencing. PCR analysis for AmpC and OXA-51 gave positive results for all strains studied. No isolates produced metallo-beta-lactamases. In all isolates ISAba1 laid upstream of blaOXA-23. The A. baumannii isolates were separated into two genotypes; genotype A had a higher prevalence (41 strains than genotype B (12 strains. Genotype A was present in four hospitals, whilst genotype B had spread in two hospitals. The high frequency of MDR OXA-23-producing A. baumannii in various hospitals in Antananarivo is curious since carbapenems are not available in Madagascar, but it emphasises the need for infection control procedures and strict adherence to them to prevent the spread of these resistant organisms in Antananarivo and also the need to control the use of carbapenems in the future.

  3. Synergistic effects of sulbactam in multi-drug-resistant Acinetobacter baumannii

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    Fatih Temocin

    2015-12-01

    Full Text Available Abstract Acinetobacter baumannii is a frequently isolated etiologic agent of nosocomial infections, especially in intensive care units. With the increase in multi-drug resistance of A. baumannii isolates, finding appropriate treatment alternatives for infections caused by these bacteria has become more difficult, and available alternate treatments include the use of older antibiotics such as colistin or a combination of antibiotics. The current study aimed to evaluate the in vitro efficacy of various antibiotic combinations against multi-drug resistant A. baumannii strains. Thirty multi-drug and carbapenem resistant A. baumannii strains isolated at the Ankara Training and Research Hospital between June 2011 and June 2012 were used in the study. Antibiotic susceptibility tests and species-level identification were performed using conventional methods and the VITEK 2 system. The effects of meropenem, ciprofloxacin, amikacin, tigecycline, and colistin alone and in combination with sulbactam against the isolates were studied using Etest (bioMérieux in Mueller-Hinton agar medium. Fractional inhibitory concentration index (FIC was used to determine the efficacy of the various combinations. While all combinations showed a predominant indifferent effect, a synergistic effect was also observed in 4 of the 5 combinations. Synergy was demonstrated in 43% of the isolates with the meropenem-sulbactam combination, in 27% of the isolates with tigecycline-sulbactam, and in 17% of the isolates with colistin-sulbactam and amikacin-sulbactam. No synergy was detected with the sulbactam-ciprofloxacin combination and antagonism was detected only in the sulbactam-colistin combination (6.66% of the isolates. Antibiotic combinations can be used as an alternative treatment approach in multi-drug resistant A. baumannii infections.

  4. Emergence of multidrug-resistant Acinetobacter baumannii producing OXA-23 Carbapenemase in Qatar

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    J.-M. Rolain

    2016-05-01

    Full Text Available The objective of our study was to describe the molecular support of carbapenem resistance from randomly selected clinical isolates of multidrug-resistant (MDR Acinetobacter baumannii as a pilot study from the Hamad Medical Corporation (HMC, Qatar. Results of our report will be used to study carbapenemases using molecular techniques in all isolated MDR A. baumannii. Forty-eight MDR A. baumannii were randomly selected from isolates preserved at HMC. Identification of all isolates was confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antibiotic resistance was tested phenotypically by Phoenix and confirmed by Etest. The molecular support of carbapenemases (blaOXA-23, blaOXA-24, blaOXA-58, blaNDM was investigated by real-time PCR. The epidemiologic relatedness of the isolates was verified by phylogenetic analysis based on partial sequences of CsuE and blaOXA-51 genes. All 48 isolates were identified as A. baumannii and were confirmed to be resistant to most antibiotics, especially meropenem, imipenems, ciprofloxacin, levofloxacin, amikacin, gentamicin and most of the β-lactams; they were sensitive to colistin. All the isolates were positive for blaOXA-23 and negative for the other tested carbapenemase genes. Clonality analysis demonstrated that different lineages were actually circulating in Qatar; and we suggest that an outbreak occurred in the medical intensive care unit of HMC between 2011 and 2012. Here we report the emergence of MDR A. baumannii producing the carbapenemase OXA-23 in Qatar.

  5. Contribution of Acinetobacter-derived cephalosporinase-30 to sulbactam resistance in Acinetobacter baumannii

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    Shu-Chen eKuo

    2015-03-01

    Full Text Available The sulbactam resistance rate in Acinetobacter baumannii has increased worldwide. Previous reports have shown that the β-lactamase blaTEM-1 confers resistance to sulbactam in A. baumannii. The purpose of this study was to examine whether other β-lactamases including, the Acinetobacter-derived cephalosporinase (ADC, OXA-23, OXA-24/72, and OXA-58 families, also contribute to sulbactam resistance in A. baumannii. The correlation between these β-lactamases and the sulbactam minimal inhibitory concentration (MIC was determined using A. baumannii clinical isolates from diverse clonality, which were collected in a nationwide surveillance program from 2002 to 2010 in Taiwan. A possible association between the genetic structure of ISAba1-blaADC-30 and sulbactam resistance was observed because this genetic structure was detected in 97% of sulbactam-resistant strains compared with 10% of sulbactam-susceptible strains. Transformation of ISAba1-blaADC-30 into susceptible strains increased the sulbactam MIC from 2 to 32 μg/ml, which required blaADC-30 overexpression using an upstream promoter in ISAba1. Flow cytometry showed that ADC-30 production increased in response to sulbactam, ticarcillin, and ceftazidime treatment. This effect was regulated at the RNA level but not by an increase in the blaADC-30 gene copy number as indicated by quantitative PCR. Purified ADC-30 decreased the inhibitory zone created by sulbactam or ceftazidime, similarly to TEM-1. In conclusion, ADC-30 overexpression conferred resistance to sulbactam in diverse clinical A. baumannii isolates.

  6. Carbapenem-resistant Acinetobacter baumannii from Serbia: revision of CarO classification.

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    Katarina Novovic

    Full Text Available Carbapenem-resistant A. baumannii present a significant therapeutic challenge for the treatment of nosocomial infections in many European countries. Although it is known that the gradient of A. baumannii prevalence increases from northern to southern Europe, this study provides the first data from Serbia. Twenty-eight carbapenem-resistant A. baumannii clinical isolates were collected at a Serbian pediatric hospital during a 2-year period. The majority of isolates (67.68% belonged to the sequence type Group 1, European clonal complex II. All isolates harbored intrinsic OXA-51 and AmpC cephalosporinase. OXA-23 was detected in 16 isolates (57.14%, OXA-24 in 23 isolates (82.14% and OXA-58 in 11 isolates (39.29%. Six of the isolates (21.43% harbored all of the analyzed oxacillinases, except OXA-143 and OXA-235 that were not detected in this study. Production of oxacillinases was detected in different pulsotypes indicating the presence of horizontal gene transfer. NDM-1, VIM and IMP were not detected in analyzed clinical A. baumannii isolates. ISAba1 insertion sequence was present upstream of OXA-51 in one isolate, upstream of AmpC in 13 isolates and upstream of OXA-23 in 10 isolates. In silico analysis of carO sequences from analyzed A. baumannii isolates revealed the existence of two out of six highly polymorphic CarO variants. The phylogenetic analysis of CarO protein among Acinetobacter species revised the previous classification CarO variants into three groups based on strong bootstraps scores in the tree analysis. Group I comprises four variants (I-IV while Groups II and III contain only one variant each. One half of the Serbian clinical isolates belong to Group I variant I, while the other half belongs to Group I variant III.

  7. A novel mutation in pmrB mediates colistin resistance during therapy of Acinetobacter baumannii.

    Science.gov (United States)

    Dahdouh, Elias; Gómez-Gil, Rosa; Sanz, Sonia; González-Zorn, Bruno; Daoud, Ziad; Mingorance, Jesús; Suárez, Monica

    2017-06-01

    Acinetobacter baumannii is a highly versatile nosocomial pathogen. Multidrug resistance among A. baumannii isolates led to the use of colistin, subsequently giving rise to colistin-resistant strains. In this study, the genetic and phenotypic profiles of two colistin-resistant A. baumannii isolates were investigated. Two A. baumannii isolates were obtained from Patient 1 (C071 and C440) and three isolates were obtained from Patient 2 (C080, C314 and C428). Susceptibility profiles were determined by VITEK ® 2 and Etest. Clonality was determined by RAPD analysis and trilocus multiplex PCR. The pmrCAB operon was sequenced and common carbapenemase genes were screened for by PCR. Doubling times, haemolysis, surface motility, biofilm formation, siderophore production and proteolytic activity were phenotypically determined. Finally, whole-genome sequencing was performed for all five isolates. Isolates C440 and C428 were resistant to colistin and were clonally identical to their sensitive counterparts. The cause of colistin resistance was traced to the previously described P233S mutation in pmrB of C440 and to a novel ΔI19 mutation in pmrB of C428. bla OXA-58-like and bla GES-5 from the strains of Patients 1 and 2, respectively, were also detected. C440 had attenuated proteolytic activity and was positive for siderophore production compared with C071. No difference in in vitro virulence was detected between isolates C080, C314 and C428. In conclusion, one common and one novel mutation were encountered in pmrB from two distinct colistin-resistant A. baumannii isolates. These mutations caused colistin resistance during therapy in two distinct clones, and only one of them had altered in vitro virulence. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  8. Cellular fatty acids as chemical markers for differentiation of Acinetobacter baumannii and Acinetobacter calcoaceticus.

    Science.gov (United States)

    Yang, Chao; Guo, Zhao Biao; Du, Zong Min; Yang, Hui Ying; Bi, Yu Jing; Wang, Gui Qin; Tan, Ya Fang

    2012-12-01

    Gas chromatography (GC) was used to investigate the cellular fatty acid (CFA) composition of 141 Acinetobacter baumannii and 32 A. calcoaceticus isolates from different locations in China and to find chemical markers to differentiate these two closely related bacteria. Whole cell fatty acid methyl esters (FAMEs) were obtained by saponification, methylation, and extraction for GC analysis, followed by a standardized Microbial Identification System (MIS) analysis. All A. baumannii and A. calcoaceticus strains contained some major fatty acids, namely, 18:1 ω9c, 16:0, Sum In Feature 3, 12:0, 17:1ω8c, 3-OH-12:0, 17:0, Sum In Feature 2, 2-OH-12:0, and 18:0 compounds. Although most of the total CFAs are similar between A. baumannii and A. calcoaceticus strains, the ratios of two pairs of CFAs, i.e., Sum In Feature 3/18:1 ω9c versus 16:0/18:1 ω9c and Sum In Feature 3/18:1 ω9c versus unknown 12.484/18:1 ω9c fatty acids, could differentiate these two closely related bacteria. A. baumannii could be easily classified into two subgroups by plotting some ratios such as Sum In Feature 3/16:0 versus 17:0 and Sum In Feature 3/2-OH-12:0 versus 17:0 fatty acids. The ratios of some CFAs could be used as chemical markers to distinguish A. baumannii from A. calcoaceticus. Copyright © 2012 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

  9. Antibiotic resistance patterns of Acinetobacter calcoaceticus-A. baumannii complex species from Colombian hospitals.

    Science.gov (United States)

    Reguero, María Teresa; Medina, Olga Esther; Hernández, María Andrea; Flórez, Diana Vanessa; Valenzuela, Emilia María; Mantilla, José Ramón

    2013-03-01

    Only automated phenotypic methods are currently used in Colombian hospitals for identifying isolates of the Acinetobacter calcoaceticus-A. baumannii complex (ACB). The phenotypical similarities in these species mean that they cannot be differentiated by manual or automated methods, thereby leading to their identification as A. baumannii, or ACB complex in clinical settings. Our objective was to identify to the species level 60 isolates, from four hospitals, evaluate their antibiotic susceptibility, and detect resistance-related genes. 16S-23S rRNA internal transcribed spacer (ITS) region and rpoB gene partial sequences were amplified. Resistance genes for cephalosporin, carbapenem and aminoglycoside were detected by PCR. Possible mutations in the quinolone resistance-determining region (QRDR) were evaluated. The association of ISAba-1 with blaOXA and blaADC genes was determined by PCR. Amplification products of ITS region, rpoB gene and some resistance genes were sequenced and compared using the BLAST tool. 16S-23S rRNA ITS region and partial rpoB gene sequence analysis allowed 51isolates to be identified as A. baumannii, 8 as A. nosocomialis, and 1 isolate as A. pitti. A. baumannii isolates were highly resistant to all antibiotics tested, while the others were susceptible to ciprofloxacin and ampicillin/sulbactam. Quinolone resistance, found only in A. baumannii, was associated with mutations in the QRDR region of gyrA and parC genes. This is the first investigation in Colombia that has identified ACB complex species using molecular methods, and determined differences in antibiotic resistance and resistance genes among the species. It is of the highest importance to identify isolates to the species level for future resistance and epidemiology studies in our region. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  10. Antimicrobial resistance determinants in imipenem-nonsusceptible Acinetobacter calcoaceticus-baumannii complex isolated in Daejeon, Korea.

    Science.gov (United States)

    Sung, Ji Youn; Kwon, Kye Chul; Cho, Hye Hyun; Koo, Sun Hoe

    2011-10-01

    Members of the Acinetobacter calcoaceticus-baumannii (Acb) complex are important opportunistic bacterial pathogens and present significant therapeutic challenges in the treatment of nosocomial infections. In the present study, we investigated the integrons and various genes involved in resistance to carbapenems, aminoglycosides, and fluoroquinolones in 56 imipenem-nonsusceptible Acb complex isolates. This study included 44 imipenem-nonsusceptible A. baumannii, 10 Acinetobacter genomic species 3, and 2 Acinetobacter genomic species 13TU strains isolated in Daejeon, Korea. The minimum inhibitory concentrations (MICs) were determined by Etest. PCR and DNA sequencing were used to identify the genes that potentially contribute to each resistance phenotype. All A. baumannii isolates harbored the bla(OXA-51)-like gene, and 21 isolates (47.7%) co-produced OXA-23. However, isolates of Acinetobacter genomic species 3 and 13TU only contained bla(IMP-1) or bla(VIM-2). Most Acb complex isolates (94.6%) harbored class 1 integrons, armA, and/or aminoglycoside-modifying enzymes (AMEs). Of particular note was the fact that armA and aph(3')-Ia were only detected in A. baumannii isolates, which were highly resistant to amikacin (MIC(50)≥256) and gentamicin (MIC(50)≥1,024). In all 44 A. baumannii isolates, resistance to fluoroquinolones was conferred by sense mutations in the gyrA and parC. However, sense mutations in parC were not found in Acinetobacter genomic species 3 or 13TU isolates. Several differences in carbapenem, aminoglycoside, and fluoroquinolone resistance gene content were detected among Acb complex isolates. However, most Acb complex isolates (87.5%) possessed integrons, carbapenemases, AMEs, and mutations in gyrA. The co-occurrence of several resistance determinants may present a significant threat.

  11. Distribution of Class I Integron among Isolates of Acinetobacter baumannii Recoverd from Burn Patients

    Directory of Open Access Journals (Sweden)

    Abdolaziz Rastegar-Lari

    2015-10-01

    Full Text Available Background: Acinetobacter baumannii, is an important opportunistic pathogens   responsible   for   nosocomial   infections.   The   aim   of   this experiment  was  to  determine  prevalence  of  Class  I  Integron  in  A. baumannii strains isolated from burn patients in Mottahari Hospital and the drug susceptibility pattern.Methods: There were 69 Acinetobacter isolates, 68 (98.5% were identified as A. baumannii. Antimicrobial susceptibility of these isolates were determined by a disk diffusion method. PCR assay for detection of blaOXA-51 like gene (for identity confirmation and intI was performed.Results:  The  most  effective  antibiotic  for  treating  A.  baumannii  was colistin, followed by tetracyclin and tobramycin. The presence of Integron class  I  was  detected  in  14.49%  of  isolates.  ESBL  and  carbapenemase production were observed in 10% and 24.6% of isolates, respectively. Conclusion: Due to the high resistance of strains lacking Integron I, the findings are although class I integrons are disseminated among clinical isolates  of  A.  baumannii,  at  present  research,  they  they  do  not  play important role in dissemination of antibiotic resistance genes in MottahariHospital in Tehran, Iran. 

  12. Antibiotic Resistance of Acinetobacter baumannii in Iran: A Systemic Review of the Published Literature.

    Science.gov (United States)

    Moradi, Jale; Hashemi, Farhad B; Bahador, Abbas

    2015-04-01

    Acinetobacter baumannii is a bacterium responsible for health care-associated infections, and it frequently develops multiple drug resistance (MDR). The prevalence of antibiotic-resistant A. baumannii in Iran has increased, and this may cause significant clinical problems. Therefore, in order to elucidate the development of antibiotic resistance, we performed a systematic review of the literature published on antibiotic-resistant A. baumannii reported in Iran. Thirty-six publications that met the criteria for inclusion were reviewed from an initial 87 papers. Selected papers published between 2008 and September 2014, were categorized on the basis of the sample collecting year been between 2001 and 2013. Analysis of data revealed that, in general, there was an increase in antimicrobial resistance. During the initial time point of these studies (2001-2007) there was a high rate of resistance to all antibiotics, with the exception of carbapenems, lipopeptides, and aminoglycosides that had a low resistance rate in comparison with the others. Also, the resistance rate was increased in one group of these three antimicrobial groups from 2010 to 2013. In particular, there was an increase in resistance to carbapenems (imipenem and meropenem) from 2010-2011 and 2012-2013, whereas no significant change in the resistance rate of the other two antimicrobial groups (lipopeptides and aminoglycosides) during the study time was observed, although we did observe certain trends in amikacin (aminoglycoside group antibiotic) between 2011-2012 and 2012-2013. These findings indicate that antimicrobial resistance of A. baumannii in Iran has increased, which may very well affect the antimicrobial resistance of this organism worldwide. Based on these results, novel prevention and treatment strategies against A. baumannii infections are warranted. Furthermore, these data may assist in revising treatment guidelines and regional policies in care units to slow the emergence of antimicrobial

  13. Study of the major essential oil compounds of Coriandrum sativum against Acinetobacter baumannii and the effect of linalool on adhesion, biofilms and quorum sensing.

    Science.gov (United States)

    Alves, Susana; Duarte, Andreia; Sousa, Sónia; Domingues, Fernanda C

    2016-01-01

    Acinetobacter baumannii is a pathogen that has the ability to adhere to surfaces in the hospital environment and to form biofilms which are increasingly resistant to antimicrobial agents. The aim of this work was to study the antimicrobial activity of the major oil compounds of Coriandrum sativum against A. baumannii. The effect of linalool on planktonic cells and biofilms of A. baumannii on different surfaces, as well as its effect on adhesion and quorum sensing was evaluated. From all the compounds evaluated, linalool was the compound with the best antibacterial activity, with minimum inhibitory concentration values between 2 and 8 μl ml(-1). Linalool also inhibited biofilm formation and dispersed established biofilms of A. baumannii, changed the adhesion of A. baumannii to surfaces and interfered with the quorum- sensing system. Thus, linalool could be a promising antimicrobial agent for controlling planktonic cells and biofilms of A. baumannii.

  14. Bigelow Expandable Activity Module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Bigelow Expandable Activity Module (BEAM) project is a NASA-industry partnership with Bigelow Aerospace (BA) that has developing the first human-rated expandable...

  15. Activity of Host Antimicrobials against Multidrug-Resistant Acinetobacter baumannii Acquiring Colistin Resistance through Loss of Lipopolysaccharide

    OpenAIRE

    García-Quintanilla, Meritxell; Pulido, Marina R.; Moreno-Martínez, Patricia; Martín-Peña, Reyes; López-Rojas, Rafael; Pachón, Jerónimo; McConnell, Michael J.

    2014-01-01

    Acinetobacter baumannii can acquire resistance to the cationic peptide antibiotic colistin through complete loss of lipopolysaccharide (LPS) expression. The activities of the host cationic antimicrobials LL-37 and human lysozyme against multidrug-resistant clinical isolates of A. baumannii that acquired colistin resistance through lipopolysaccharide loss were characterized. We demonstrate that LL-37 has activity against strains lacking lipopolysaccharide that is similar to that of their colis...

  16. Mutant prevention concentration of colistin alone and in combination with rifampicin for multidrug-resistant Acinetobacter baumannii

    OpenAIRE

    Nordqvist, H.; Nilsson, Lennart E; Claesson, Carina

    2016-01-01

    Colistin-susceptible isolates of Acinetobacter baumannii often contain subpopulations that are resistant to colistin. Monotherapy with colistin can lead to selective growth of these subpopulations and emergence of colistin-resistant strains. Our objectives were to explore the susceptibility pattern of colistin-resistant subpopulations and investigate if combining colistin with a second antibiotic could prevent their selective growth. Four colistin-susceptible clinical isolates of A. baumannii...

  17. Clonal Spread of Carbapenem Non-susceptible Acinetobacter baumannii in an Intensive Care Unit in a Teaching Hospital in China

    OpenAIRE

    Zhong, Qiao; Xu, Weidong; Wu, Yuanjian; Xu, Hongxing

    2012-01-01

    Background This study was aimed to investigate the genetic diversity and antibiotic resistance profile of the nosocomial infection agent Acinetobacter baumannii from a medical intensive care unit (ICU) in a teaching hospital in Suzhou, China. Methods The genetic relationship among A. baumannii isolates in an ICU was investigated using multilocus sequence typing (MLST). The antibiotic resistance pattern was determined by performing an antibiotic susceptible test, which included an agar dilutio...

  18. Antimicrobial Resistance Mechanisms and Genetic Diversity of Multidrug-Resistant Acinetobacter baumannii Isolated from a Teaching Hospital in Malaysia.

    Science.gov (United States)

    Biglari, Shirin; Hanafiah, Alfizah; Mohd Puzi, Shaliawani; Ramli, Ramliza; Rahman, Mostafizur; Lopes, Bruno Silvester

    2017-07-01

    Multidrug-resistant (MDR) Acinetobacter baumannii has increasingly emerged as an important nosocomial pathogen. The aim of this study was to determine the resistance profiles and genetic diversity in A. baumannii clinical isolates in a tertiary medical center in Malaysia. The minimum inhibitory concentrations of carbapenems (imipenem and meropenem), cephalosporins (ceftazidime and cefepime), and ciprofloxacin were determined by E-test. PCR and sequencing were carried out for the detection of antibiotic resistance genes and mutations. Clonal relatedness among A. baumannii isolates was determined by REP-PCR. Sequence-based typing of OXA-51 and multilocus sequence typing were performed. One hundred twenty-five of 162 (77.2%) A. baumannii isolates had MDR phenotype. From the 162 A. baumannii isolates, 20 strain types were identified and majority of A. baumannii isolates (66%, n = 107) were classified as strain type 1 and were positive for ISAba1-bla OXA-23 and ISAba1-bla ADC and had mutations in both gyrA and parC genes at positions, 83 and 80, resulting in serine-to-leucine conversion. REP-PCR analysis showed 129 REP types that generated 31 clones with a 90% similarity cutoff value. OXA-66 variant of the bla OXA-51-like genes was predominantly detected among our A. baumannii clinical isolates belonging to ST195 (found in six clones: 1, 8, 9, 19, 27, and 30) and ST208 (found in clone 21). The study helps us in understanding the genetic diversity of A. baumannii isolates in our setting and confirms that international clone II is the most widely distributed clone in Universiti Kebangsaan Malaysia Medical Centre, Malaysia.

  19. Is the use of low-pressure pulsatile lavage for pressure ulcer management associated with environmental contamination with Acinetobacter baumannii?

    Science.gov (United States)

    Ho, Chester H; Johnson, Tova; Miklacic, Joan; Donskey, Curtis J

    2009-10-01

    Ho CH, Johnson T, Miklacic J, Donskey CJ. Is the use of low-pressure pulsatile lavage for pressure ulcer management associated with environmental contamination with Acinetobacter baumannii? To determine the extent of environmental contamination associated with low-pressure pulsatile lavage of stage III or IV pressure ulcers in patients with spinal cord injury (SCI) when routine infection control precautions are used for wounds colonized or infected with Acinetobacter baumannii. Prospective investigation in which pressure ulcer cultures and environmental cultures were obtained before and after low-pressure pulsatile lavage treatment, and before and after regular dressing changes. Environmental cultures included the patient's bedrail and settle plates placed 0.6, 1.5, and 2.4m from the wound to assess airborne spread of A. baumannii. SCI inpatient unit in a Department of Veterans Affairs Medical Center. Inpatients (N=15) with SCI receiving daily low-pressure pulsatile lavage treatment for stage III or IV pressure ulcers with standard dressing change, as well as regular dressing changes without low-pressure pulsatile lavage at other times of the day. Standard, regular dressing changes and dressing changes with low-pressure pulsatile lavage. Comparison of frequency of environmental contamination with A. baumannii associated with low-pressure pulsatile lavage versus regular dressing changes. Of the 15 SCI inpatients meeting inclusion criteria, 9 (60%) grew A. baumannii from their wounds. Of the 9 patients with wound cultures positive for A. baumannii, only 1 (11%) had environmental contamination with this organism after performance of low-pressure pulsatile lavage, and the same patient had environmental contamination after a standard dressing change. The antibiotic susceptibility patterns of the wound and environmental A. baumannii isolates were identical. Low-pressure pulsatile lavage using the infection control methods described is not associated with an increased

  20. Molecular epidemiology of Acinetobacter baumannii and Acinetobacter nosocomialis in Germany over a 5-year period (2005-2009).

    Science.gov (United States)

    Schleicher, X; Higgins, P G; Wisplinghoff, H; Körber-Irrgang, B; Kresken, M; Seifert, H

    2013-08-01

    To investigate the species distribution within the Acinetobacter calcoaceticus-Acinetobacter baumannii complex and the molecular epidemiology of A. baumannii and Acinetobacter nosocomialis, 376 Acinetobacter isolates were collected prospectively from hospitalized patients at 15 medical centres in Germany during three surveillance studies conducted over a 5-year period. Species identification was performed by molecular methods. Imipenem minimum inhibitory concentrations (MIC) were determined by broth microdilution. The prevalence of the most common carbapenemase-encoding genes was investigated by oxacillinase (OXA) -multiplex polymerase chain reaction (PCR). The molecular epidemiology was investigated by repetitive sequence-based PCR (rep-PCR; DiversiLab™). Acinetobacter pittii was the most prevalent Acinetobacter species (n = 193), followed by A. baumannii (n = 140), A. calcoaceticus (n = 10) and A. nosocomialis (n = 8). The majority of A. baumannii was represented by sporadic isolates (n = 70, 50%) that showed unique rep-PCR patterns, 25 isolates (18%) clustered with one or two other isolates, and only 45 isolates (32%) belonged to one of the previously described international clonal lineages. The most prevalent clonal lineage was international clone (IC) 2 (n = 34) and IC 1 (n = 6). According to CLSI, 25 A. baumannii isolates were non-susceptible to imipenem (MIC ≥ 8 mg/L), all of which produced an OXA-58-like or OXA-23-like carbapenemase. The rate of imipenem susceptibility among A. baumannii isolates decreased from 96% in 2005 to 76% in 2009. All other Acinetobacter isolates were susceptible to imipenem. The population structure of carbapenem-susceptible A. baumannii in Germany is highly diverse. Imipenem non-susceptibility was strongly associated with the clonal lineages IC 2 and IC 1. These data underscore the high clonality of carbapenem-resistant A. baumannii isolates. © 2012 The Authors. Clinical Microbiology and Infection © 2012 European Society of

  1. First report of an OXA-23 carbapenemase-producing Acinetobacter baumannii clinical isolate related to Tn2006 in Spain.

    Science.gov (United States)

    Espinal, P; Macià, M D; Roca, I; Gato, E; Ruíz, E; Fernández-Cuenca, F; Oliver, A; Rodríguez-Baño, J; Bou, G; Tomás, M; Vila, J

    2013-01-01

    A carbapenem-resistant Acinetobacter baumannii clinical isolate belonging to European clone II and sequence type 2 was recovered from a patient in the Son Espases hospital in Mallorca, Spain. Genetic analysis showed the presence of the bla(OXA-23) gene in association with the widely disseminated transposon Tn2006. This is the first reported identification of A. baumannii carrying bla(OXA-23) in Spain.

  2. Detection of OXA-Type Carbapenemase Genes in Acinetobacter baumannii Isolates from Nosocomial Infections in Isfahan Hospitals, Iran

    OpenAIRE

    Vajihe Karbasizade; Leila Heidari; Reyhaneh Jafari

    2016-01-01

    "> Background: Acinetobacter baumannii as one of the causes of nosocomial infections has becomeresistant to almost all antimicrobial agents. The emergence of resistance to carbapenems, one ofthe last drugs on the shelf, is the major concern about A. baumannii antimicrobial resistance.Resistance to carbapenems is mediated by production of class B and D carbapenemases. The aimof this study was to detect the resistance genes including blaOXA-23, 24, 51, and 58 in A. baumanniiisolates from nos...

  3. Control of multi-resistant bacteria and ventilator-associated pneumonia: is it possible with changes in antibiotics?

    Directory of Open Access Journals (Sweden)

    Elisa M. Jukemura

    Full Text Available Potent antimicrobial agents have been developed as a response to the development of antibiotic-resistant bacteria, which especially affect patients with prolonged hospitalization in Intensive Care Units (ICU and who had been previously treated with antimicrobials, especially third-generation cephalosporins.This study was to determine how changes in the empirical treatment of infections in ICU patients affect the incidence of Gram-negative bacteria species and their susceptibility to antimicrobials, and examine the impact of these changes on nosocomial infections. A prospective interventional study was performed in a university hospital during two periods: 1 First period (September 1999 to February 2000; and 2 Second period (August 2000 to December 2000; empirical treatment was changed from ceftriaxone and/or ceftazidime in the first period to piperacillin/tazobactam in the second. ICU epidemiological and infection control rates, as well as bacterial isolates from upper airways were analyzed. Ceftazidime consumption dropped from 34.83 to 0.85 DDD/1000 patients per day (p=0.004. Piperacillin/tazobactam was originally not available; its consumption reached 157.07 DDD/1000 patients per day in the second period (p=0.0002. Eighty-seven patients and 66 patients were evaluated for upper airway colonization in the first and second periods, respectively. There was a significant decrease in the incidence of K. pneumoniae (p=0.004 and P. mirabilis (p=0.036, restoration of K. pneumoniae susceptibility to cephalosporins (p<0.0001 and reduction of ventilator-associated pneumonia rates (p<0.0001. However, there was an increase in P. aeruginosa incidence (p=0.005 and increases in ceftazidime (p=0.003 and meropenem (p<0.0001 susceptibilities. Changing antimicrobial selective pressure on multi-resistant Gram-negative bacteria helps control ventilator-associated pneumonia and decreases antimicrobial resistance.

  4. Presence of biofilm containing viable multiresistant organisms despite terminal cleaning on clinical surfaces in an intensive care unit.

    Science.gov (United States)

    Vickery, K; Deva, A; Jacombs, A; Allan, J; Valente, P; Gosbell, I B

    2012-01-01

    Despite recent attention to surface cleaning and hand hygiene programmes, multiresistant organisms (MROs) continue to be isolated from the hospital environment. Biofilms, consisting of bacteria embedded in exopolymeric substances (EPS) are difficult to remove due to their increased resistance to detergents and disinfectants, and periodically release free-swimming planktonic bacteria back into the environment which may may act as an infection source. To establish whether reservoirs of MROs exist in the environment as biofilms. Following terminal cleaning, equipment and furnishings were removed aseptically from an intensive care unit (ICU) and subjected to culture and scanning electron microscopy (SEM). Samples were placed in 5 mL of tryptone soya broth, sonicated for 5 min before plate culture on horse blood agar, Brillance MRSA and Brilliance VRE agar plates. Samples for SEM were fixed in 3% glutaraldehyde and hexamethyldisilizane (HMDS) prior to sputter-coating with gold and examination in an electron microscope. Biofilm was demonstrated visually on the sterile supply bucket, the opaque plastic door, the venetian blind cord, and the sink rubber, whereas EPS alone was seen on the curtain. Viable bacteria were grown from three samples, including MRSA from the venetian blind cord and the curtain. Biofilm containing MROs persist on clinical surfaces from an ICU despite terminal cleaning, suggesting that current cleaning practices are inadequate to control biofilm development. The presence of MROs being protected within these biofilms may be the mechanism by which MROs persist within the hospital environment. Copyright © 2011 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  5. Tissue expander infections in children: look beyond the expander pocket.

    Science.gov (United States)

    Mason, A C; Davison, S P; Manders, E K

    1999-11-01

    Infection of the expander pocket is the most common complication encountered with soft-tissue expansion. It is usually due to direct inoculation with skin flora either at the time of expander insertion or from extrusion of the device. The authors report two cases of infection of tissue expanders in which the children had concomitant infected sites distant from the prosthesis. Etiological bacteria of common pediatric infections like otitis media and pharyngitis were cultured from the infected expander pocket, raising suspicion that translocation of the organism to the expander had occurred. Aggressive antibiotic treatment, removal of the prosthesis, and flap advancement is advocated.

  6. Estudo da Similaridade Genética de Amostras de Acinetobacter baumannii Produtoras de Carbapenemases do Tipo OXA Isoladas em Diversos Hospitais Brasileiros

    OpenAIRE

    Werneck, Jessica Sanchez de Freitas [UNIFESP

    2010-01-01

    In this dissertation we present two studies involving carbapenem-resistant Acinetobacter baumannii clinical isolates due to the production of carbapenems modifying enzymes, the OXA-type carbapenemases. The first study aimed to determine the genetic relationship of multi-drug-resistant A. baumannii producing OXA-23 that was isolated in distinct Brazilian cities. A total of 91 A. baumannii clinical isolates were recovered from 17 medical centers located at eight cities, namely São Paulo (SP), R...

  7. Effect of a ventilator-focused intervention on the rate of Acinetobacter baumannii infection among ventilated patients.

    Science.gov (United States)

    Cohen, Regev; Shimoni, Zvi; Ghara, Riad; Ram, Ron; Ben-Ami, Ronen

    2014-09-01

    Acinetobacter baumannii is a leading cause of ventilator-associated pneumonia, often as a result of ventilator equipment contamination. Evidence-based guidance on optimal care of ventilator equipment to prevent infection is lacking. Here, we report on a significant and persistent reduction in A baumannii infection rates achieved by introducing a strict policy on ventilator care. We implemented an institution-wide ventilator care policy that included routine exchange of breathing circuits and external bacterial filters (every 7-14 days) and replacement followed by routine sterilization of internal bacterial filters (every 4-8 weeks). We analyzed sputum cultures and patient outcomes among ventilated patients before and after the intervention. Between January 2012 and March 2013, 321 patients ventilated for more than 3 days comprised the study cohort. Health care-associated A baumannii acquisition was significantly reduced during the postintervention period (33% vs 16%; odds ratio, 0.39; 95% confidence interval, 0.23-0.67; P = .0008). Additionally, the median time to A baumannii acquisition was significantly longer postintervention (59 vs 21 days; P < .0001). A baumannii ventilator-associated pneumonia risk was also reduced postintervention (odds ratio, 0.39; P = .005). Implementing a stricter standard of ventilator care than that currently defined in published guidelines can significantly decrease health care-associated A baumannii acquisition and related adverse outcomes among ventilated patients. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  8. Effect of Chlorine Exposure on the Survival and Antibiotic Gene Expression of Multidrug Resistant Acinetobacter baumannii in Water

    Directory of Open Access Journals (Sweden)

    Deepti Prasad Karumathil

    2014-02-01

    Full Text Available Acinetobacter baumannii is a multidrug resistant pathogen capable of causing a wide spectrum of clinical conditions in humans. Acinetobacter spp. is ubiquitously found in different water sources. Chlorine being the most commonly used disinfectant in water, the study investigated the effect of chlorine on the survival of A. baumannii in water and transcription of genes conferring antibiotic resistance. Eight clinical isolates of A. baumannii, including a fatal meningitis isolate (ATCC 17978 (~108 CFU/mL were separately exposed to free chlorine concentrations (0.2, 1, 2, 3 and 4 ppm with a contact time of 30, 60, 90 and 120 second. The surviving pathogen counts at each specified contact time were determined using broth dilution assay. In addition, real-time quantitative PCR (RT-qPCR analysis of the antibiotic resistance genes (efflux pump genes and those encoding resistance to specific antibiotics of three selected A. baumannii strains following exposure to chlorine was performed. Results revealed that all eight A. baumannii isolates survived the tested chlorine levels during all exposure times (p > 0.05. Additionally, there was an up-regulation of all or some of the antibiotic resistance genes in A. baumannii, indicating a chlorine-associated induction of antibiotic resistance in the pathogen.

  9. Evaluating the Impact of Antibiotic Exposures as Time-Dependent Variables on the Acquisition of Carbapenem-Resistant Acinetobacter baumannii.

    Science.gov (United States)

    Munoz-Price, L Silvia; Rosa, Rossana; Castro, Jose G; Laowansiri, Panthipa; Latibeaudiere, Rachel; Namias, Nicholas; Tarima, Sergey

    2016-10-01

    To determine the time-dependent effect of antibiotics on the initial acquisition of carbapenem-resistant Acinetobacter baumannii. Retrospective cohort study. Forty-bed trauma ICU in Miami, FL. All consecutive patients admitted to the unit from November 1, 2010, to November 30, 2011. None. Patients underwent surveillance cultures at admission to the unit and weekly thereafter. The primary outcome was the acquisition of carbapenem-resistant A. baumannii on surveillance cultures. Daily antibiotic exposures during the time of observation were used to construct time-dependent variables, including cumulative exposures (in grams and daily observed doses [defined daily doses]). Among 360 patients, 45 (12.5%) became colonized with carbapenem-resistant A. baumannii. Adjusted Cox models showed that each additional point in the Acute Physiologic and Chronic Health Evaluation score increased the hazard by 4.8% (hazard ratio, 1.048; 95% CI, 1.010-1.087; p = 0.0124) and time-dependent exposure to carbapenems quadrupled the hazard (hazard ratio, 4.087; 95% CI, 1.873-8.920; p = 0.0004) of acquiring carbapenem-resistant A. baumannii. Additionally, adjusted Cox models determined that every additional carbapenem defined daily dose increased the hazard of acquiring carbapenem-resistant A. baumannii by 5.1% (hazard ratio, 1.051; 95% CI, 1.007-1.093; p = 0.0243). Carbapenem exposure quadrupled the hazards of acquiring A. baumannii even after controlling for severity of illness.

  10. Microbiological features and clinical impact of the type VI secretion system (T6SS) in Acinetobacter baumannii isolates causing bacteremia.

    Science.gov (United States)

    Kim, Jungok; Lee, Ji-Young; Lee, Haejeong; Choi, Ji Young; Kim, Dae Hun; Wi, Yu Mi; Peck, Kyong Ran; Ko, Kwan Soo

    2017-10-03

    We investigated the genetic background and microbiological features of T6SS-positive Acinetobacter baumannii isolates and clinical impact of the T6SS in patients with A. baumannii bacteremia. One hundred and 62 A. baumannii isolates from patients with bacteremia in 2 tertiary-care hospitals in Korea were included in this study. Approximately one-third (51/162, 31.5%) of the A. baumannii clinical isolates possessed the hcp gene, and the hcp-positive isolates were found in several genotypes in multilocus sequence typing. The expression and secretion of Hcp protein varied among the clinical isolates. A. baumannii isolates with detectable Hcp secretion (T6SS+) could better outcompete Escherichia coli compared with T6SS- isolates, including hcp-negative and inactivated hcp-positive isolates. In addition, T6SS+ isolates showed higher biofilm-forming activity and better survival in the presence of normal human serum than the T6SS- isolates. T6SS+ isolates were more frequently detected in patients with catheter-related bloodstream infection, haematopoietic stem cell transplant recipients, and patients receiving immunosuppressive agents. However, T6SS was not a prognostic factor for mortality. Our results suggest that the T6SS of A. baumannii is associated with virulence and contributes to infections in immunocompromised patients and those with implanted medical devices.

  11. Diversity of Acinetobacter baumannii in Four French Military Hospitals, as Assessed by Multiple Locus Variable Number of Tandem Repeats Analysis

    Science.gov (United States)

    Hauck, Yolande; Soler, Charles; Jault, Patrick; Mérens, Audrey; Gérome, Patrick; Nab, Christine Mac; Trueba, François; Bargues, Laurent; Thien, Hoang Vu; Vergnaud, Gilles; Pourcel, Christine

    2012-01-01

    Background Infections by A. calcoaceticus-A. baumannii (ACB) complex isolates represent a serious threat for wounded and burn patients. Three international multidrug-resistant (MDR) clones (EU clone I-III) are responsible for a large proportion of nosocomial infections with A. baumannii but other emerging strains with high epidemic potential also occur. Methodology/Principal Findings We automatized a Multiple locus variable number of tandem repeats (VNTR) analysis (MLVA) protocol and used it to investigate the genetic diversity of 136 ACB isolates from four military hospitals and one childrens hospital. Acinetobacter sp other than baumannii isolates represented 22.6% (31/137) with a majority being A. pittii. The genotyping protocol designed for A.baumannii was also efficient to cluster A. pittii isolates. Fifty-five percent of A. baumannii isolates belonged to the two international clones I and II, and we identified new clones which members were found in the different hospitals. Analysis of two CRISPR-cas systems helped define two clonal complexes and provided phylogenetic information to help trace back their emergence. Conclusions/Significance The increasing occurrence of A. baumannii infections in the hospital calls for measures to rapidly characterize the isolates and identify emerging clones. The automatized MLVA protocol can be the instrument for such surveys. In addition, the investigation of CRISPR/cas systems may give important keys to understand the evolution of some highly successful clonal complexes. PMID:22984530

  12. Diversity of Acinetobacter baumannii in four French military hospitals, as assessed by multiple locus variable number of tandem repeats analysis.

    Directory of Open Access Journals (Sweden)

    Yolande Hauck

    Full Text Available BACKGROUND: Infections by A. calcoaceticus-A. baumannii (ACB complex isolates represent a serious threat for wounded and burn patients. Three international multidrug-resistant (MDR clones (EU clone I-III are responsible for a large proportion of nosocomial infections with A. baumannii but other emerging strains with high epidemic potential also occur. METHODOLOGY/PRINCIPAL FINDINGS: We automatized a Multiple locus variable number of tandem repeats (VNTR analysis (MLVA protocol and used it to investigate the genetic diversity of 136 ACB isolates from four military hospitals and one childrens hospital. Acinetobacter sp other than baumannii isolates represented 22.6% (31/137 with a majority being A. pittii. The genotyping protocol designed for A.baumannii was also efficient to cluster A. pittii isolates. Fifty-five percent of A. baumannii isolates belonged to the two international clones I and II, and we identified new clones which members were found in the different hospitals. Analysis of two CRISPR-cas systems helped define two clonal complexes and provided phylogenetic information to help trace back their emergence. CONCLUSIONS/SIGNIFICANCE: The increasing occurrence of A. baumannii infections in the hospital calls for measures to rapidly characterize the isolates and identify emerging clones. The automatized MLVA protocol can be the instrument for such surveys. In addition, the investigation of CRISPR/cas systems may give important keys to understand the evolution of some highly successful clonal complexes.

  13. Expanding hollow metal rings

    Science.gov (United States)

    Peacock, Harold B [Evans, GA; Imrich, Kenneth J [Grovetown, GA

    2009-03-17

    A sealing device that may expand more planar dimensions due to internal thermal expansion of a filler material. The sealing material is of a composition such that when desired environment temperatures and internal actuating pressures are reached, the sealing materials undergoes a permanent deformation. For metallic compounds, this permanent deformation occurs when the material enters the plastic deformation phase. Polymers, and other materials, may be using a sealing mechanism depending on the temperatures and corrosivity of the use. Internal pressures are generated by either rapid thermal expansion or material phase change and may include either liquid or solid to gas phase change, or in the gaseous state with significant pressure generation in accordance with the gas laws. Sealing material thickness and material composition may be used to selectively control geometric expansion of the seal such that expansion is limited to a specific facing and or geometric plane.

  14. Expandable pattern casting research

    Science.gov (United States)

    1993-09-01

    The Expandable Pattern Casting (EPC) Process is a developing foundry technology that allows designers the opportunity to consolidate parts, reduce machining, and minimize assembly operations. An air gauging system was developed for measuring foam patterns; exact shrinkage depended on type and density of the foam. Compaction studies showed that maximum sand densities in cavities and under overhangs are achieved with vibrational amplitudes 0.001-0.004 in., and that sand moved most freely within a few inches of the top free surface. Key to complete mold filling while minimizing casting defects lies in removing the foam decomposition products. The most precise iron castings were made by EPC in four commercial EPC foundries, with attention paid to molding and compaction. EP cast 60-45-12 ductile iron had yield strengths, ultimate strengths, and elastic modulus similar to conventionally cast ductile iron cast from the same ladle.

  15. Expanding or postponing?

    DEFF Research Database (Denmark)

    Jensen, Tanja Dall; Caswell, Dorte

    2017-01-01

    setting. Working with data from 97 team meetings in a social work setting, we identify two patterns of negotiation in talk; expanding and postponing. ‘Expanding’ covers a group of interactional actions involving turn-taking and closure, while ‘postponing’ includes a group of actions whereby assessments......In this paper, we examine patterns of negotiation in multi-party interaction in social work. We draw on Strauss’ theory of negotiated order and a conversation analytical approach, seeking to gain insight into the complex accomplishment of making a decision in an inter-professional and multiparty...... or topics are avoided or made irrelevant. Both are examples of the complex ways in which team members negotiate both the institutional order and the decision to be made in the specific case in situ....

  16. Carriage of multidrug-resistant bacteria among pediatric patients ...

    African Journals Online (AJOL)

    Carriage of multidrug-resistant bacteria among pediatric patients before and during their hospitalization in a tertiary pediatric unit in Tunisia. ... carbapenemase-producing Enterobacteriaceae (CPE), multiresistant Pseudomonas aeruginosa and multiresistant Acinetobacter baumannii) pose a threat to healthcare Worldwide.

  17. In vitro activity of tigecycline in combination with various antimicrobials against multidrug resistant Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Petrosillo Nicola

    2009-05-01

    Full Text Available Abstract Background Infections sustained by multidrug-resistant (MDR and pan-resistant Acinetobacter baumannii have become a challenging problem in Intensive Care Units. Tigecycline provided new hope for the treatment of MDR A. baumannii infections, but isolates showing reduced susceptibility have emerged in many countries, further limiting the therapeutic options. Empirical combination therapy has become a common practice to treat patients infected with MDR A. baumannii, in spite of the limited microbiological and clinical evidence supporting its efficacy. Here, the in vitro interaction of tigecycline with seven commonly used anti-Acinetobacter drugs has been assessed. Methods Twenty-two MDR A. baumannii isolates from Intensive Care Unit (ICU patients and two reference strains for the European clonal lineages I and II (including 3, 15 and 6 isolates that were resistant, intermediate and susceptible to tigecycline, respectively were tested. Antimicrobial agents were: tigecycline, levofloxacin, piperacillin-tazobactam, amikacin, imipenem, rifampicin, ampicillin-sulbactam, and colistin. MICs were determined by the broth microdilution method. Antibiotic interactions were determined by chequerboard and time-kill assays. Only antibiotic combinations showing synergism or antagonism in both chequerboard and time-kill assays were accepted as authentic synergistic or antagonistic interactions, respectively. Results Considering all antimicrobials in combination with tigecycline, chequerboard analysis showed 5.9% synergy, 85.7% indifference, and 8.3% antagonism. Tigecycline showed synergism with levofloxacin (4 strains; 16.6%, amikacin (2 strains; 8.3%, imipenem (2 strains; 8.3% and colistin (2 strains; 8.3%. Antagonism was observed for the tigecycline/piperacillin-tazobactam combination (8 strains; 33.3%. Synergism was detected only among tigecycline non-susceptible strains. Time-kill assays confirmed the synergistic interaction between tigecycline and

  18. Multiple drug resistant carbapenemases producing Acinetobacter baumannii isolates harbours multiple R-plasmids

    Directory of Open Access Journals (Sweden)

    Rajagopalan Saranathan

    2014-01-01

    Full Text Available Background & objectives: The nosocomial human pathogen Acinetobacter baumannii has high propensity to develop resistance to antimicrobials and to become multidrug resistant (MDR, consequently complicating the treatment. This study was carried out to investigate the presence of resistant plasmids (R-plasmids among the clinical isolates of A. baumannii. In addition, the study was performed to check the presence of common β-lactamases encoding genes on these plasmids. Methods: A total of 55 clinical isolates of A. baumannii were included in the study and all were subjected to plasmid DNA isolation, followed by PCR to check the presence of resistance gene determinants such as blaOXA-23 , blaOXA-51, blaOXA-58 and blaIMP-1 on these plasmids that encode for oxacillinase (OXA and metallo-β-lactamase (MBL type of carbapenemases. Plasmid curing experiments were carried out on selected isolates using ethidium bromide and acridine orange as curing agents and the antibiotic resistance profiles were evaluated before and after curing. Results: All the isolates were identified as A. baumannii by 16SrDNA amplification and sequencing. Plasmid DNA isolated from these isolates showed the occurrence of multiple plasmids with size ranging from 500bp to ≥ 25 kb. The percentage of blaOXA-51 and blaOXA-23 on plasmids were found to be 78 and 42 per cent, respectively and 20 isolates (36% carried blaIMP-1 gene on plasmids. Significant difference was observed in the antibiograms of plasmid cured isolates when compared to their parental ones. The clinical isolates became susceptible to more than two antibiotic classes after curing of plasmids indicating plasmid borne resistance. Interpretation & conclusions: Our study determined the plasmid mediated resistance mechanisms and occurrence of different resistance genes on various plasmids isolated from MDR A. baumannii. The present findings showed the evidence for antibiotic resistance mediated through multiple plasmids in

  19. Investigations of multiresistance to antibiotics and chemotherapeutics and extended spectrum beta: Lactamase effect (ESBL test in strains E.coli and salmonella originating from domestic animals

    Directory of Open Access Journals (Sweden)

    Mišić Dušan

    2006-01-01

    Full Text Available The presence of multiresistance to the effects of antibiotics and chemotherapeutics and extended spectrum beta-lactamase were examined in 45 strains of E. coli and 35 strains of Salmonella. The strains of E. coli originated from several species of domestic animals: dogs, cats, poultry, and cattle, and 30 strains of Salmonella originated from poultry, 4 strains from cattle, and 1 strain from swine. The presence of the following serovarieties was established using serological examinations: Salmonella Enteritidis 17 strains, Salmonella Gallinarum 1 strain, Salmonella Hartford 5 strains, Salmonella Anatum 1 strain, Salmonella Typhimurium 4 strains, Salmonella Agona 1 strain, Salmonella Infantis 1 strain, Salmonella Thompson var. Berlin 1 strain, Salmonella Tennessee 1 strain, Salmonella Senftenberg 1 strain, Salmonella Glostrup 1 strain, and Salmonella Hadar 1 strain. In the examinations of the listed strains we used antibiogram discs of ampicillin, amoxicillin with clavulanic acid, cephalexin, cephtriaxon, cephotaxim, cephtazidime, aztreonam, gentamycin, chloramphenicol, tetracycline, cyprofloxacine, and a combination of sulphamethoxasole and trimethoprim. The lowest prevalence of multiresistance in E. Coli strains to 3 or more antibiotics was established in dogs 20%, and the highest in 60% strains originating from swine. In 62.88% strains of Salmonella we established sensitivity to all applied antibiotics. Resistance was also established in a small number of the examined strains to ampicillin (11 strains, to tetracycline (5 strains, to amoxicillin with clavulanic acid (5 strains, to sulphamethoxasole with trimethoprim (5 strains, to gentamycin (3 strains, and to cloramphenicol (1 strain. Of all the examined strains of Salmonella, 6 strains originating from poultry exhibited multiresistence. The presence of extended spectrum beta-lactamase effects examined using the ESBL test, was not established in strains of E. coli and Salmonella strains.

  20. The Artful Universe Expanded

    Energy Technology Data Exchange (ETDEWEB)

    Bassett, B A [Institute of Cosmology and Gravitation, University of Portsmouth (United Kingdom)

    2005-07-29

    The cosmos is an awfully big place and there is no better guide to its vast expanse and fascinating nooks and crannies than John Barrow. A professor of mathematical sciences at Cambridge University, Barrow embodies that rare combination of highly polished writer and expert scientist. His deft touch brings together the disparate threads of human knowledge and weaves them into a tapestry as rich and interesting for the expert as it is for the layperson. The Artful Universe Expanded is an updated edition of this popular book first published in 1995. It explores the deeply profound manner in which natural law and the nature of the cosmos have moulded and shaped us, our cultures and the very form of our arts and music-a new type of 'cosmic' anthropology. The main themes Barrow chooses for revealing this new anthropology are the subjects of evolution, the size of things, the heavens and the nature of music. The book is a large, eclectic repository of knowledge often unavailable to the layperson, hidden in esoteric libraries around the world. It rivals The Da Vinci Code for entertainment value and insights, but this time it is Nature's code that is revealed. It is rare indeed to find common threads drawn through topics as diverse as The Beetles, Bach and Beethoven or between Jackson Pollock, the Aztecs, Kant, Picasso, Byzantine mosaics, uranium-235 and the helix nebula. Barrow unerringly binds them together, presenting them in a stimulating, conversational style that belies the amount of time that must have gone into researching this book. Dip into it at random, or read it from cover to cover, but do read it. The Artful Universe Expanded is an entertaining antidote to the oft-lamented pressures to know more and more about less and less and the apparently inexorable march of specialization. On reading this book one can, for a short time at least, hold in one's mind a vision that unifies science, art and culture and glimpse a universal tapestry of great

  1. The Artful Universe Expanded

    International Nuclear Information System (INIS)

    Bassett, B A

    2005-01-01

    The cosmos is an awfully big place and there is no better guide to its vast expanse and fascinating nooks and crannies than John Barrow. A professor of mathematical sciences at Cambridge University, Barrow embodies that rare combination of highly polished writer and expert scientist. His deft touch brings together the disparate threads of human knowledge and weaves them into a tapestry as rich and interesting for the expert as it is for the layperson. The Artful Universe Expanded is an updated edition of this popular book first published in 1995. It explores the deeply profound manner in which natural law and the nature of the cosmos have moulded and shaped us, our cultures and the very form of our arts and music-a new type of 'cosmic' anthropology. The main themes Barrow chooses for revealing this new anthropology are the subjects of evolution, the size of things, the heavens and the nature of music. The book is a large, eclectic repository of knowledge often unavailable to the layperson, hidden in esoteric libraries around the world. It rivals The Da Vinci Code for entertainment value and insights, but this time it is Nature's code that is revealed. It is rare indeed to find common threads drawn through topics as diverse as The Beetles, Bach and Beethoven or between Jackson Pollock, the Aztecs, Kant, Picasso, Byzantine mosaics, uranium-235 and the helix nebula. Barrow unerringly binds them together, presenting them in a stimulating, conversational style that belies the amount of time that must have gone into researching this book. Dip into it at random, or read it from cover to cover, but do read it. The Artful Universe Expanded is an entertaining antidote to the oft-lamented pressures to know more and more about less and less and the apparently inexorable march of specialization. On reading this book one can, for a short time at least, hold in one's mind a vision that unifies science, art and culture and glimpse a universal tapestry of great beauty. (book review)

  2. Structure determination of LpxD from the lipopolysaccharide-synthesis pathway of Acinetobacter baumannii

    International Nuclear Information System (INIS)

    Badger, John; Chie-Leon, Barbara; Logan, Cheyenne; Sridhar, Vandana; Sankaran, Banumathi; Zwart, Peter H.; Nienaber, Vicki

    2012-01-01

    Crystal structures of the protein LpxD from A. baumannii were solved in apo forms that are suitable for structure-based antibacterial drug discovery. Acinetobacter baumannii is a Gram-negative bacterium that is resistant to many currently available antibiotics. The protein LpxD is a component of the biosynthetic pathway for lipopolysaccharides in the outer membrane of this bacterium and is a potential target for new antibacterial agents. This paper describes the structure determination of apo forms of LpxD in space groups P2 1 and P4 3 22. These crystals contained six and three copies of the protein molecule in the asymmetric unit and diffracted to 2.8 and 2.7 Å resolution, respectively. A comparison of the multiple protein copies in the asymmetric units of these crystals reveals a common protein conformation and a conformation in which the relative orientation between the two major domains in the protein is altered

  3. Expression, purification, crystallization and preliminary crystallographic analysis of the phosphoglycerate kinase from Acinetobacter baumannii

    International Nuclear Information System (INIS)

    Baretta, Kayla; Garen, Craig; Yin, Jiang; James, Michael N. G.

    2012-01-01

    Approximately five decades have passed with only one or two new antibiotics making it into clinical use. Phosphoglycerate kinase from A. baumanii has been selected as a potential target for antibiotic development; this paper presents the initial structural biological results from this research. Acinetobacter baumannii is a common multidrug-resistant clinical pathogen that is often found in hospitals. The A. baumannii phosphoglycerate kinase (AbPGK) is involved in the key energy-producing pathway of glycolysis and presents a potential target for antibiotic development. AbPGK has been expressed and purified; it was crystallized using lithium sulfate as the precipitant. The AbPGK crystals belonged to space group P222 1 . They diffracted to a resolution of 2.5 Å using synchrotron radiation at the Canadian Light Source

  4. Antimicrobial Combinations against Pan-Resistant Acinetobacter baumannii Isolates with Different Resistance Mechanisms.

    Directory of Open Access Journals (Sweden)

    Gleice Cristina Leite

    Full Text Available The study investigated the effect of antibiotic combinations against 20 clinical isolates of A. baumannii (seven colistin-resistant and 13 colistin-susceptible with different resistance mechanisms. Clinical data, treatment, and patient mortality were evaluated. The following methods were used: MIC, PCRs, and outer membrane protein (OMP analysis. Synergy was investigated using the checkerboard and time-kill methods. Clonality was evaluated by PFGE. Based on clonality, the whole genome sequence of six A. baumannii isolates was analyzed. All isolates were resistant to meropenem, rifampicin, and fosfomycin. OXA-23 and OXA-143 were the most frequent carbapenemases found. Four isolates showed loss of a 43kDa OMP. The colistin-susceptible isolates belonged to different clones and showed the highest synergistic effect with fosfomycin-amikacin. Among colistin-resistant isolates, the highest synergistic effect was observed with the combinations of colistin-rifampicin followed by colistin-vancomycin. All colistin-resistant isolates harbored blaOXA-23-like and belonged to CC113. Clinical and demographic data were available for 18 of 20 patients. Fourteen received treatment and eight patients died during treatment. The most frequent site of infection was the blood in 13 of 14 patients. Seven patients received vancomycin plus an active drug against A. baumannii; however, mortality did not differ in this group. The synergistic effect was similar for colistin-susceptible isolates of distinct clonal origin presenting with the same resistance mechanism. Overall mortality and death during treatment was high, and despite the high synergism in vitro with vancomycin, death did not differ comparing the use or not of vancomycin plus an active drug against A. baumannii.

  5. Investigation of the surface of colistin susceptible and resistant Acinetobacter baumannii

    OpenAIRE

    Soon, Rachel Li-Xia

    2017-01-01

    Colistin, a cationic amphipathic polymyxin antibiotic, has been revived as a last-line therapy for Gram-negative multidrug-resistant infections. Colistin heteroresistant and -resistant Acinetobacter baumannii have prompted fears that these infections may become untreatable. The proposed ‘self-promoted uptake’ mechanism of colistin action suggests that electrostatic and hydrophobic interactions with lipopolysaccharide (LPS) facilitate permeation through the complex Gram-negative outer membrane...

  6. Wide distribution of carbapenem resistant Acinetobacter baumannii in burns patients in Iran

    OpenAIRE

    Farshadzadeh, Zahra; Hashemi, Farhad B.; Rahimi, Sara; Pourakbari, Babak; Esmaeili, Davoud; Haghighi, Mohammad A.; Majidpour, Ali; Shojaa, Saeed; Rahmani, Maryam; Gharesi, Samira; Aziemzadeh, Masoud; Bahador, Abbas

    2015-01-01

    Antimicrobial resistance in carbapenem non-susceptible Acinetobacter baumannii (CNSAb) is a major public health concern globally. This study determined the antibiotic resistance and molecular epidemiology of CNSAb isolates from a referral burn center in Tehran, Iran. Sixty-nine CNSAb isolates were tested for susceptibility to antimicrobial agents using the E test methodology. Multiple locus variable number tandem repeat analysis (MLVA), Multilocus sequence typing (MLST) and multiplex PCR were...

  7. Characterising the Transmission Dynamics of Acinetobacter baumannii in Intensive Care Units Using Hidden Markov Models.

    Directory of Open Access Journals (Sweden)

    Tan N Doan

    Full Text Available Little is known about the transmission dynamics of Acinetobacter baumannii in hospitals, despite such information being critical for designing effective infection control measures. In the absence of comprehensive epidemiological data, mathematical modelling is an attractive approach to understanding transmission process. The statistical challenge in estimating transmission parameters from infection data arises from the fact that most patients are colonised asymptomatically and therefore the transmission process is not fully observed. Hidden Markov models (HMMs can overcome this problem. We developed a continuous-time structured HMM to characterise the transmission dynamics, and to quantify the relative importance of different acquisition sources of A. baumannii in intensive care units (ICUs in three hospitals in Melbourne, Australia. The hidden states were the total number of patients colonised with A. baumannii (both detected and undetected. The model input was monthly incidence data of the number of detected colonised patients (observations. A Bayesian framework with Markov chain Monte Carlo algorithm was used for parameter estimations. We estimated that 96-98% of acquisition in Hospital 1 and 3 was due to cross-transmission between patients; whereas most colonisation in Hospital 2 was due to other sources (sporadic acquisition. On average, it takes 20 and 31 days for each susceptible individual in Hospital 1 and Hospital 3 to become colonised as a result of cross-transmission, respectively; whereas it takes 17 days to observe one new colonisation from sporadic acquisition in Hospital 2. The basic reproduction ratio (R0 for Hospital 1, 2 and 3 was 1.5, 0.02 and 1.6, respectively. Our study is the first to characterise the transmission dynamics of A. baumannii using mathematical modelling. We showed that HMMs can be applied to sparse hospital infection data to estimate transmission parameters despite unobserved events and imperfect detection of

  8. CRISPR-cas subtype I-Fb in Acinetobacter baumannii: evolution and utilization for strain subtyping.

    Science.gov (United States)

    Karah, Nabil; Samuelsen, Ørjan; Zarrilli, Raffaele; Sahl, Jason W; Wai, Sun Nyunt; Uhlin, Bernt Eric

    2015-01-01

    Clustered regularly interspaced short palindromic repeats (CRISPR) are polymorphic elements found in the genome of some or all strains of particular bacterial species, providing them with a system of acquired immunity against invading bacteriophages and plasmids. Two CRISPR-Cas systems have been identified in Acinetobacter baumannii, an opportunistic pathogen with a remarkable capacity for clonal dissemination. In this study, we investigated the mode of evolution and diversity of spacers of the CRISPR-cas subtype I-Fb locus in a global collection of 76 isolates of A. baumannii obtained from 14 countries and 4 continents. The locus has basically evolved from a common ancestor following two main lineages and several pathways of vertical descent. However, this vertical passage has been interrupted by occasional events of horizontal transfer of the whole locus between distinct isolates. The isolates were assigned into 40 CRISPR-based sequence types (CST). CST1 and CST23-24 comprised 18 and 9 isolates, representing two main sub-clones of international clones CC1 and CC25, respectively. Epidemiological data showed that some of the CST1 isolates were acquired or imported from Iraq, where it has probably been endemic for more than one decade and occasionally been able to spread to USA, Canada, and Europe. CST23-24 has shown a remarkable ability to cause national outbreaks of infections in Sweden, Argentina, UAE, and USA. The three isolates of CST19 were independently imported from Thailand to Sweden and Norway, raising a concern about the prevalence of CST19 in Thailand. Our study highlights the dynamic nature of the CRISPR-cas subtype I-Fb locus in A. baumannii, and demonstrates the possibility of using a CRISPR-based approach for subtyping a significant part of the global population of A. baumannii.

  9. Prevalence of digestive tract colonization of carbapenem-resistant Acinetobacter baumannii in hospitals in Saudi Arabia.

    Science.gov (United States)

    Aljindan, Reem; Bukharie, Huda; Alomar, Amer; Abdalhamid, Baha

    2015-04-01

    Carbapenem-resistant Acinetobacter baumannii is a major health problem worldwide, especially in intensive care units (ICUs). This study aimed to detect the prevalence of A. baumannii colonization of the gastrointestinal tract of patients admitted to the ICU in two hospitals in Saudi Arabia. In addition, it aimed to characterize the molecular mechanisms of carbapenem resistance in these isolates. From January to June 2014, 565 rectal swab specimens were screened for Acinetobacer strains and carbapenem resistance using CHROMagar Acinetobacter and CHROMagar KPC agar plates, respectively. Organism identification and susceptibility were detected using the Vitek 2 system. A total of 47 Acinetobacter spp. were detected, and 35 were resistant to carbapenem, making the prevalence of Acinetobacter spp. 8.3% (47/565) and carbapenem resistance (6.2%, 35/565). The 47 strains showed remarkable clonal diversity as revealed by PFGE. Using PCR, OXA-51, a chromosomal marker for A. baumannii, was detected in 46 strains. OXA-23 β-lactamase was detected in all 35 carbapenem-resistant A. baumannii. No IMP, VIM, SPM, SIM, GIM, KPC or NDM β-lactamases were detected in these isolates. Thus, OXA-23 was the main mechanism of carbapenem resistance in these isolates. To the best of our knowledge, this is the first study to detect the prevalence of Acinetobacter colonization in the digestive tract of ICU patients in Saudi Arabia. This study revealed the importance of having well-established protocols for early identification of these multidrug-resistant organisms, optimizing infection-control strategies and having active surveillance studies to reduce morbidity, mortality and cost. © 2015 The Authors.

  10. Infections caused by Acinetobacter baumannii in recipients of hematopoietic stem cell transplantation

    Directory of Open Access Journals (Sweden)

    Khalid Ahmed Al-Anazi

    2014-07-01

    Full Text Available Acinetobacter baumannii (A. baumannii is a Gram-negative, strictly aerobic, non-fermentative coccobacillus which is widely distributed in nature. Recently, it has emerged as a major cause of health care-associated infections in addition to its capacity to cause community acquired infections. Risk factors for A. baumannii infections and bacteremia in recipients of hematopoietic stem cell transplantation include: severe underlying illness such as hematological malignancy, prolonged use of broad-spectrum antibiotics, invasive instrumentation such as central venous catheters or endotracheal intubation, colonization of respiratory, gastrointestinal or urinary tracts in addition to severe immunosuppression caused by using corticosteroids for treating graft versus host disease. The organism causes a wide spectrum of clinical manifestations, but serious complications such as bacteremia, septic shock, ventilator-associated pneumonia, extensive soft tissue necrosis and rapidly progressive systemic infections that ultimately lead to multiorgan failure and death are prone to occur in severely immunocompromised hosts. The organism is usually resistant to many antimicrobials including penicillins, cephalosporins, trimethoprim-sulfamethoxazole, almost all flouroquinolones and most of the aminoglycosides. The recently increasing resistance to carbapenems, colistin and polymyxins is alarming. Additionally, there are geographic variations in the resistance patterns and several globally and regionally resistant strains have already been described. Successful management of A.baumannii infections depends upon appropriate utilization of antibiotics and strict application of preventive and infection control measures. In uncomplicated infections, the use of a single active beta-lactam may be justified, while definitive treatment of complicated infections in critically ill individuals may require drug combinations such as colistin and rifampicin or colistin and

  11. Characterisation of successive Acinetobacter baumannii isolates from a deceased haemophagocytic lymphohistiocytosis patient.

    Science.gov (United States)

    Choi, Hyeon Jin; Kil, Min Cheol; Choi, Ji-Young; Kim, Sun Ju; Park, Ki-Sup; Kim, Yae-Jean; Ko, Kwan Soo

    2017-01-01

    In this study, 38 Acinetobacter baumannii isolates successively isolated from blood, skin swabs and tracheal aspirates from a single patient who died from haemophagocytic lymphohistiocytosis were investigated. The isolates were collected between March 2012 and August 2012. A. baumannii genotypes were determined by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). In vitro antimicrobial susceptibility testing was performed and colistin heteroresistance and persistence were evaluated. The structure of AbaR resistance islands was explored, and serum sensitivity was determined. Based on MLST analysis, all 38 A. baumannii isolates showed the same sequence type (ST138). However, PFGE analysis showed that isolates from blood samples belonged to different genotypes depending on the isolation time: whilst blood isolates obtained at the early stages showed restriction patterns similar to those of isolates from other sources, isolates obtained at later stages exhibited a distinct pattern. All isolates were resistant to imipenem, cefepime, ciprofloxacin and piperacillin/tazobactam. Five isolates from tracheal aspirates and one from a skin swab were resistant to polymyxins, and two isolates from skin swabs and one from another source were non-susceptible to tigecycline. All colistin-susceptible isolates showed heteroresistance to colistin, and four were persisters. Isolates from blood showed higher survival rates against human serum than those from other sources. This study shows that the patient was infected with more than one A. baumannii strain. Heteroresistance, persistence or evasion of the innate immune response may explain the failure of antimicrobial treatments in this patient. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  12. Characterization and identification of newly isolated Acinetobacter baumannii strain serdang 1 for phenol removal

    Science.gov (United States)

    Yadzir, Z. H. M.; Shukor, M. Y.; Nazir, M. S.; Abdullah, M. A.

    2012-09-01

    A new indigenous bacterial strain from Malaysian soil contaminated with petroleum waste had been successfully isolated, characterized and identified for phenol removal. The gram negative bacteria showed 98% identity with Acinetobacter baumannii based on Biolog{trade mark, serif} Identification System and the determination of a partial 16S ribosomal RNA (rRNA) sequence. The isolate clustered with species belonging to Acinetobacter clade in a 16S rDNA-based neighbour-joining phylogenetic tree.

  13. First Detection of GES-5 Carbapenemase-Producing Acinetobacter baumannii Isolate.

    Science.gov (United States)

    Al-Agamy, Mohamed H; Jeannot, Katy; El-Mahdy, Taghrid S; Shibl, Atef M; Kattan, Wael; Plésiat, Patrick; Courvalin, Patrice

    2017-07-01

    This study was conducted to investigate the molecular epidemiology of resistance in Acinetobacter baumannii isolates collected at a hospital in Riyadh, Saudi Arabia, from January through December 2010. Twenty-seven A. baumannii were highly resistant (MIC 90 > 256 μg/ml) to ceftazidime, cefepime, and aztreonam. Imipenem resistance was seen in 24 isolates, of which 18 had an minimum inhibitory concentration (MIC) >32 μg/mL. Ciprofloxacin, gentamicin, and amikacin resistance was found in 93%, 52%, and 37% of all the isolates, respectively. Moreover, 8 (30%) isolates showed colistin resistance, and 15 (56%) were found to have MICs ≥4 μg/mL for tigecycline. The frequency of ADC, GES-1, GES-11, and GES-5 were 96.3% (n = 26), 18.5% (n = 5), 11% (n = 3), and 3.7% (n = 1), respectively. OXA-23 was found in 63% (n = 17) of the isolates; ISAba1 was found upstream of OXA-23 in 16. OXA-24/40 was detected in only one strain. Multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) analysis revealed that the 27 strains were distributed in 8 sequence types (STs) and 16 clonal pulsotypes (A-P). Five singleton STs were identified, including ST15 and ST113-ST116. The emergence of multidrug-resistant A. baumannii is becoming a major concern in Saudi Arabia. Metallo-β-lactamases have no role in carbapenem resistance in this collection. The spread of OXA-23 in our strains occurred across different STs and pulsotypes, unlike what has been observed in many other countries. PFGE typing was more discriminatory than MLST. The high frequency of colistin and tigecycline resistance found in the isolates calls for continuous monitoring. This study describes the first identification of GES-5 conferring carbapenem resistance in A. baumannii.

  14. Reduction in chlorhexidine efficacy against multi-drug-resistant Acinetobacter baumannii international clone II.

    Science.gov (United States)

    Hayashi, M; Kawamura, K; Matsui, M; Suzuki, M; Suzuki, S; Shibayama, K; Arakawa, Y

    2017-03-01

    Nosocomial infections caused by Acinetobacter baumannii international clone II (IC II) can cause severe clinical outcomes. Differential evaluation of bactericidal efficacy of chlorhexidine gluconate (CHX) and benzethonium chloride (BZT) disinfectants against IC II and non-IC II isolates. Minimum inhibitory concentrations (MICs) of CHX and BZT were determined for 137 A. baumannii IC II, 99 non-IC II and 69 non-baumannii isolates, further classified according to MIC values into disinfectant-reduced susceptible (DRS) and disinfectant-susceptible (DS) groups. Time-kill curves and minimum bactericidal concentrations (MBCs) were evaluated for representative isolates in each group. CHX and BZT MIC 90 s for IC II isolates were 100 and 175mg/L, respectively, but those for non-IC II and non-baumannii isolates were <100mg/L. Nevertheless, time-kill curves indicated that CHX and BZT reduced live bacterial cell number by 5 log 10 for IC II and non-IC II isolates within 30s when used at 1000mg/L, comparable to practical use concentrations. CHX MBC at 30s was 1000mg/L for IC II and non-IC II isolates, and was not influenced by addition of 3% bovine serum albumin (BSA); BZT MBC at 30s was 100mg/L without BSA and increased up to 500mg/L upon addition of BSA. No significant differences in BSA were found between DRS and DS isolates. CHX and BZT were effective against Acinetobacter spp. including IC II at a concentration of 1000mg/L and exposure for at least 30s, but their concentrations should be considered carefully to ensure sufficient effects in both clinical and healthcare settings. Copyright © 2016 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  15. Validation of a Novel Murine Wound Model of Acinetobacter baumannii Infection

    Science.gov (United States)

    Thompson, Mitchell G.; Black, Chad C.; Pavlicek, Rebecca L.; Honnold, Cary L.; Wise, Matthew C.; Alamneh, Yonas A.; Moon, Jay K.; Kessler, Jennifer L.; Si, Yuanzheng; Williams, Robert; Yildirim, Suleyman; Kirkup, Benjamin C.; Green, Romanza K.; Hall, Eric R.; Palys, Thomas J.

    2014-01-01

    Patients recovering from traumatic injuries or surgery often require weeks to months of hospitalization, increasing the risk for wound and surgical site infections caused by ESKAPE pathogens, which include A. baumannii (the ESKAPE pathogens are Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). As new therapies are being developed to counter A. baumannii infections, animal models are also needed to evaluate potential treatments. Here, we present an excisional, murine wound model in which a diminutive inoculum of a clinically relevant, multidrug-resistant A. baumannii isolate can proliferate, form biofilms, and be effectively treated with antibiotics. The model requires a temporary, cyclophosphamide-induced neutropenia to establish an infection that can persist. A 6-mm-diameter, full-thickness wound was created in the skin overlying the thoracic spine, and after the wound bed was inoculated, it was covered with a dressing for 7 days. Uninoculated control wounds healed within 13 days, whereas infected, placebo-treated wounds remained unclosed beyond 21 days. Treated and untreated wounds were assessed with multiple quantitative and qualitative techniques that included gross pathology, weight loss and recovery, wound closure, bacterial burden, 16S rRNA community profiling, histopathology, peptide nucleic acid-fluorescence in situ hybridization, and scanning electron microscopy assessment of biofilms. The range of differences that we are able to identify with these measures in antibiotic- versus placebo-treated animals provides a clear window within which novel antimicrobial therapies can be assessed. The model can be used to evaluate antimicrobials for their ability to reduce specific pathogen loads in wounded tissues and clear biofilms. Ultimately, the mouse model approach allows for highly powered studies and serves as an initial multifaceted in vivo assessment prior to

  16. The Capsular Polysaccharide of Acinetobacter baumannii Is an Obstacle for Therapeutic Passive Immunization Strategies.

    Science.gov (United States)

    Wang-Lin, Shun Xin; Olson, Ruth; Beanan, Janet M; MacDonald, Ulrike; Balthasar, Joseph P; Russo, Thomas A

    2017-12-01

    Acinetobacter baumannii has become an important concern for human health due to rapid development and wide spread of antimicrobial-resistant strains and high mortality associated with the infection. Passive immunizations with antisera targeting outer membrane proteins (OMPs) have shown encouraging results in protecting mice from A. baumannii infection, but monoclonal anti-OMP antibodies have not been developed, and their potential therapeutic properties have not been explored. The goal of this report is to evaluate the antibacterial activity of monoclonal antibodies (MAbs) targeting outer membrane protein A (OmpA) of A. baumannii Five anti-OmpA MAbs were developed using hybridoma technology and showed strong binding to strain ATCC 19606. However, low antibody binding was observed when they were tested against six clinical isolates, which included extensively drug-resistant strains. In contrast, high binding to an isogenic K1 capsule-negative mutant (AB307.30) was shown, suggesting that capsular polysaccharide mediated the inhibition of MAb binding to OmpA. Anti-OmpA MAbs increased the macrophage-mediated bactericidal activity of AB307.30 but failed to increase phagocytic killing of capsule-positive strains. Capsular polysaccharide was also protective against complement-mediated bactericidal activity in human ascites in the presence and absence of opsonization. Lastly, passive immunization with anti-OmpA MAbs did not confer protection against challenge with AB307-0294, the encapsulated parent strain of AB307.30, in a mouse sepsis infection model. These results reveal the important role of capsule polysaccharide in shielding OmpA and thereby inhibiting anti-OmpA MAb binding to clinical isolates. This property of capsule hindered the therapeutic utility of anti-OmpA MAbs, and it may apply to other conserved epitopes in A. baumannii . Copyright © 2017 American Society for Microbiology.

  17. The Artful Universe Expanded

    Science.gov (United States)

    Barrow, John D.

    2005-07-01

    Our love of art, writes John Barrow, is the end product of millions of years of evolution. How we react to a beautiful painting or symphony draws upon instincts laid down long before humans existed. Now, in this enhanced edition of the highly popular The Artful Universe , Barrow further explores the close ties between our aesthetic appreciation and the basic nature of the Universe. Barrow argues that the laws of the Universe have imprinted themselves upon our thoughts and actions in subtle and unexpected ways. Why do we like certain types of art or music? What games and puzzles do we find challenging? Why do so many myths and legends have common elements? In this eclectic and entertaining survey, Barrow answers these questions and more as he explains how the landscape of the Universe has influenced the development of philosophy and mythology, and how millions of years of evolutionary history have fashioned our attraction to certain patterns of sound and color. Barrow casts the story of human creativity and thought in a fascinating light, considering such diverse topics as our instinct for language, the origins and uses of color in nature, why we divide time into intervals as we do, the sources of our appreciation of landscape painting, and whether computer-generated fractal art is really art. Drawing on a wide variety of examples, from the theological questions raised by St. Augustine and C.S. Lewis to the relationship between the pure math of Pythagoras and the music of the Beatles, The Artful Universe Expanded covers new ground and enters a wide-ranging debate about the meaning and significance of the links between art and science.

  18. Impact of carbapenem resistance on clinical and economic outcomes among patients with Acinetobacter baumannii infection in Colombia.

    Science.gov (United States)

    Lemos, E V; de la Hoz, F P; Alvis, N; Einarson, T R; Quevedo, E; Castañeda, C; Leon, Y; Amado, C; Cañon, O; Kawai, K

    2014-02-01

    Acinetobacter baumannii is a major cause of healthcare-associated infection, often affecting critically ill patients. The purpose of the study was to examine the associations of carbapenem resistance with mortality, length of hospital stay and hospital costs among patients infected with A. baumannii in intensive-care units (ICUs) in Colombia. A prospective, multicentre cohort study was conducted among 165 patients with A. baumannii infection admitted to ICUs between April 2006 and April 2010. Patients with carbapenem-resistant A. baumannii had higher risk of 30-day mortality than patients with carbapenem-susceptible A. baumannii in the univariate analysis (unadjusted hazard ratio = 2.12; 95% CI 1.14-3.95; p 0.018). However, carbapenem resistance was not significantly associated with risk of mortality (adjusted hazard ratio = 1.45; 95% CI 0.74-2.87; p 0.28) after adjusting for APACHE II score and other confounding factors. We did not find a significant difference in length of stay in ICU after the onset of infection between the two groups in the multivariate analysis (adjusted mean = 13.1 days versus 10.5 days; p 0.14). The average total cost of hospitalization among patients with carbapenem-resistant A. baumannii was significantly higher than that among patients with carbapenem-susceptible A. baumannii in the multivariate analysis (adjusted cost; US$ 11 359 versus US$ 7049; p <0.001). Carbapenem resistance was not significantly associated with mortality, though we are unable to rule out an increased risk due to the limited sample size. Carbapenem resistance was associated with an additional cost of hospitalization. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

  19. Use of Comparative Genomics To Characterize the Diversity of Acinetobacter baumannii Surveillance Isolates in a Health Care Institution

    Science.gov (United States)

    Wallace, Lalena; Daugherty, Sean C.; Nagaraj, Sushma; Johnson, J. Kristie; Harris, Anthony D.

    2016-01-01

    Despite the increasing prevalence of the nosocomial pathogen Acinetobacter baumannii, little is known about which genomic components contribute to clinical presentation of this important pathogen. Most whole-genome comparisons of A. baumannii have focused on specific genomic regions associated with phenotypes in a limited number of genomes. In this work, we describe the results of a whole-genome comparative analysis of 254 surveillance isolates of Acinetobacter species, 203 of which were A. baumannii, isolated from perianal swabs and sputum samples collected as part of an infection control active surveillance program at the University of Maryland Medical Center. The collection of surveillance isolates includes both carbapenem-susceptible and -resistant isolates. Based on the whole-genome phylogeny, the A. baumannii isolates collected belong to two major phylogenomic lineages. Results from multilocus sequence typing indicated that one of the major phylogenetic groups of A. baumannii was comprised solely of strains from the international clonal lineage 2. The genomic content of the A. baumannii isolates was examined using large-scale BLAST score ratio analysis to identify genes that are associated with carbapenem-susceptible and -resistant isolates, as well as genes potentially associated with the source of isolation. This analysis revealed a number of genes that were exclusive or at greater frequency in each of these classifications. This study is the most comprehensive genomic comparison of Acinetobacter isolates from a surveillance study to date and provides important information that will contribute to our understanding of the success of A. baumannii as a human pathogen. PMID:27458211

  20. Insect-derived cecropins display activity against Acinetobacter baumannii in a whole-animal high-throughput Caenorhabditis elegans model.

    Science.gov (United States)

    Jayamani, Elamparithi; Rajamuthiah, Rajmohan; Larkins-Ford, Jonah; Fuchs, Beth Burgwyn; Conery, Annie L; Vilcinskas, Andreas; Ausubel, Frederick M; Mylonakis, Eleftherios

    2015-03-01

    The rise of multidrug-resistant Acinetobacter baumannii and a concomitant decrease in antibiotic treatment options warrants a search for new classes of antibacterial agents. We have found that A. baumannii is pathogenic and lethal to the model host organism Caenorhabditis elegans and have exploited this phenomenon to develop an automated, high-throughput, high-content screening assay in liquid culture that can be used to identify novel antibiotics effective against A. baumannii. The screening assay involves coincubating C. elegans with A. baumannii in 384-well plates containing potential antibacterial compounds. At the end of the incubation period, worms are stained with a dye that stains only dead animals, and images are acquired using automated microscopy and then analyzed using an automated image analysis program. This robust assay yields a Z' factor consistently greater than 0.7. In a pilot experiment to test the efficacy of the assay, we screened a small custom library of synthetic antimicrobial peptides (AMPs) that were synthesized using publicly available sequence data and/or transcriptomic data from immune-challenged insects. We identified cecropin A and 14 other cecropin or cecropin-like peptides that were able to enhance C. elegans survival in the presence of A. baumannii. Interestingly, one particular hit, BR003-cecropin A, a cationic peptide synthesized by the mosquito Aedes aegypti, showed antibiotic activity against a panel of Gram-negative bacteria and exhibited a low MIC (5 μg/ml) against A. baumannii. BR003-cecropin A causes membrane permeability in A. baumannii, which could be the underlying mechanism of its lethality. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  1. Use of Comparative Genomics To Characterize the Diversity of Acinetobacter baumannii Surveillance Isolates in a Health Care Institution.

    Science.gov (United States)

    Wallace, Lalena; Daugherty, Sean C; Nagaraj, Sushma; Johnson, J Kristie; Harris, Anthony D; Rasko, David A

    2016-10-01

    Despite the increasing prevalence of the nosocomial pathogen Acinetobacter baumannii, little is known about which genomic components contribute to clinical presentation of this important pathogen. Most whole-genome comparisons of A. baumannii have focused on specific genomic regions associated with phenotypes in a limited number of genomes. In this work, we describe the results of a whole-genome comparative analysis of 254 surveillance isolates of Acinetobacter species, 203 of which were A. baumannii, isolated from perianal swabs and sputum samples collected as part of an infection control active surveillance program at the University of Maryland Medical Center. The collection of surveillance isolates includes both carbapenem-susceptible and -resistant isolates. Based on the whole-genome phylogeny, the A. baumannii isolates collected belong to two major phylogenomic lineages. Results from multilocus sequence typing indicated that one of the major phylogenetic groups of A. baumannii was comprised solely of strains from the international clonal lineage 2. The genomic content of the A. baumannii isolates was examined using large-scale BLAST score ratio analysis to identify genes that are associated with carbapenem-susceptible and -resistant isolates, as well as genes potentially associated with the source of isolation. This analysis revealed a number of genes that were exclusive or at greater frequency in each of these classifications. This study is the most comprehensive genomic comparison of Acinetobacter isolates from a surveillance study to date and provides important information that will contribute to our understanding of the success of A. baumannii as a human pathogen. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  2. Antibacterial activity of a newly developed peptide-modified lysin against Acinetobacter baumannii and Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Hang eYang

    2015-12-01

    Full Text Available The global emergence of multidrug-resistant (MDR bacteria is a growing threat to public health worldwide. Natural bacteriophage lysins are promising alternatives in the treatment of infections caused by Gram-positive pathogens, but not Gram-negative ones, like Acinetobacter baumannii and Pseudomonas aeruginosa, due to the barriers posed by their outer membranes. Recently, modifying a natural lysin with an antimicrobial peptide was found able to break the barriers, and to kill Gram-negative pathogens. Herein, a new peptide-modified lysin (PlyA was constructed by fusing the cecropin A peptide residues 1–8 (KWKLFKKI with the OBPgp279 lysin and its antibacterial activity was studied. PlyA showed good and broad antibacterial activities against logarithmic phase A. baumannii and P. aeruginosa, but much reduced activities against the cells in stationary phase. Addition of outer membrane permeabilizers (EDTA and citric acid could enhance the antibacterial activity of PlyA against stationary phase cells. Finally, no antibacterial activity of PlyA could be observed in some bio-matrices, such as culture media, milk, and sera. In conclusion, we reported here a novel peptide-modified lysin with significant antibacterial activity against both logarithmic (without OMPs and stationary phase (with OMPs A. baumannii and P. aeruginosa cells in buffer, but further optimization is needed to achieve broad activity in diverse bio-matrices.

  3. Inhaled colistin for treatment of pneumonia due to colistin-only-susceptible Acinetobacter baumannii.

    Science.gov (United States)

    Choi, Hee Kyoung; Kim, Young Keun; Kim, Hyo Youl; Uh, Young

    2014-01-01

    Colistin is used for the treatment of pneumonia associated with multidrug- resistant Acinetobacter baumannii and Pseudomonas aeruginosa. However, the best route of administration and dosage is not known. We report our experience with aerosolized colistin in twelve patients with pneumonia caused by colistin-only-susceptible (COS) A. baumannii. We retrospectively reviewed patients' medical records who were treated with aerosolized colistin for the treatment of pneumonia. Ten patients were treated only with aerosolized colistin inhalation and two patients received a 3-day course intravenous colistin, and then switched to colistin inhalation therapy. The median duration of aerosolized colistin therapy was 17 days (5-31 days). Four patients were treated only with aerosolized colistin, whereas 4 patients received concomitant glycopeptides, and 4 received concomitant levofloxacin or cefoperazone/sulbactam. At the end of the therapy, the clinical response rate and bacteriological clearance rate was 83% and 50%, respectively. Colistin-resistant strains were isolated from 3 patients after aerosolized colistin therapy; however, all of them showed favorable clinical response. The median interval between inhalation therapy and resistance was 7 days (range 5-19 days). Acute kidney injury developed in 3 patients. Two patients experienced Clostridium difficile associated diarrhea. One patient developed fever and skin rash after aerosolized colistin therapy. No patient developed neurotoxicity or bronchospasm. Colistin inhalation therapy is deemed tolerable and safe, and could be beneficial as an adjuctive therapy for the management of pneumonia due to COS A. baumannii. However, the potential development of colistin resistance cannot be overlooked.

  4. Activity of Gallium Meso- and Protoporphyrin IX against Biofilms of Multidrug-Resistant Acinetobacter baumannii Isolates

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    David Chang

    2016-03-01

    Full Text Available Acinetobacter baumannii is a challenging pathogen due to antimicrobial resistance and biofilm development. The role of iron in bacterial physiology has prompted the evaluation of iron-modulation as an antimicrobial strategy. The non-reducible iron analog gallium(III nitrate, Ga(NO33, has been shown to inhibit A. baumannii planktonic growth; however, utilization of heme-iron by clinical isolates has been associated with development of tolerance. These observations prompted the evaluation of iron-heme sources on planktonic and biofilm growth, as well as antimicrobial activities of gallium meso- and protoporphyrin IX (Ga-MPIX and Ga-PPIX, metal heme derivatives against planktonic and biofilm bacteria of multidrug-resistant (MDR clinical isolates of A. baumannii in vitro. Ga(NO33 was moderately effective at reducing planktonic bacteria (64 to 128 µM with little activity against biofilms (≥512 µM. In contrast, Ga-MPIX and Ga-PPIX were highly active against planktonic bacteria (0.25 to 8 µM. Cytotoxic effects in human fibroblasts were observed following exposure to concentrations exceeding 128 µM of Ga-MPIX and Ga-PPIX. We observed that the gallium metal heme conjugates were more active against planktonic and biofilm bacteria, possibly due to utilization of heme-iron as demonstrated by the enhanced effects on bacterial growth and biofilm formation.

  5. Safety and effectiveness of colistin compared with tobramycin for multi-drug resistant Acinetobacter baumannii infections

    Directory of Open Access Journals (Sweden)

    Cohen Karen

    2009-03-01

    Full Text Available Abstract Background Nosocomial infections due to multi-drug resistant Acinetobacter baumannii are often treated with colistin, but there are few data comparing its safety and efficacy with other antimicrobials. Methods A retrospective cohort study of patients treated with colistin or tobramycin for A. baumannii infections in intensive care units (ICUs at Groote Schuur hospital. Colistin was used for A. baumannii isolates which were resistant to all other available antimicrobials. In the tobramycin group, 53% of the isolates were only susceptible to tobramycin and colistin. We assessed ICU mortality, nephrotoxicity and time to the first negative culture. Results 32 patients, with similar admission APACHE scores and serum creatinine, were treated with each antimicrobial. There were no significant differences between the colistin and tobramycin groups in ICU mortality (p = 0.54, nephrotoxicity (p = 0.67, change in creatinine from baseline to highest subsequent value (p = 0.11 and time to microbiological clearance (p = 0.75. The hazard ratio for total in-hospital survival in patients treated with colistin compared to tobramycin was 0.43 (95% CI 0.19 to 0.99. Conclusion Our study suggests that colistin and tobramycin have similar risks of nephrotoxicity and are equally efficacious. Colistin is an acceptable antibiotic for the treatment of A. baumanii infections when the organism is resistant to other available antimicrobials.

  6. Molecular Epidemiology of Carbapenem Non-Susceptible Acinetobacter baumannii in France

    Science.gov (United States)

    Jeannot, Katy; Diancourt, Laure; Vaux, Sophie; Thouverez, Michelle; Ribeiro, Amandina; Coignard, Bruno; Courvalin, Patrice; Brisse, Sylvain

    2014-01-01

    Carbapenem-resistant Acinetobacter baumannii have emerged globally. The objective of this study was to investigate the epidemiology, clonal diversity and resistance mechanisms of imipenem non-susceptible A. baumannii isolates in France. Between December 2010 and August 2011, 132 notifications were collected, including 37 outbreaks corresponding to 242 cases (2 to 55 per cluster). Multilocus sequence typing, pulsed-field gel electrophoresis (PFGE) and characterisation of carbapenemase-encoding genes were performed on 110 non-repetitive isolates. Gene bla OXA-23 was the most frequently detected (82%), followed by bla OXA-24 (11%) and bla OXA-58 (7%). Eleven sequence types (ST) were distinguished, among which sequence types ST1, ST2 (64%), ST20, ST25, ST85 and ST107. Isolates from epidemiological clusters had the same ST and resistance genes, indicating probable transmission within centres. In contrast, PFGE types of isolates differed among centres, arguing against transmission among centers. This study provides the first epidemiological snapshot of the population of A. baumannii with reduced susceptibility to carbapenems from France, and further underlines the predominance of international clones. PMID:25517732

  7. Quorum sensing molecules production by nosocomial and soil isolates Acinetobacter baumannii.

    Science.gov (United States)

    Erdönmez, Demet; Rad, Abbas Yousefi; Aksöz, Nilüfer

    2017-12-01

    Acinetobacter species remain alive in hospitals on various surfaces, both dry and moist, forming an important source of hospital infections. These bacteria are naturally resistant to many antibiotic classes. Although the role of the quorum sensing system in regulating the virulence factors of Acinetobacter species has not been fully elucidated, it has been reported that they play a role in bacterial biofilm formation. The biofilm formation helps them to survive under unfavorable growth conditions and antimicrobial treatments. It is based on the accumulation of bacterial communication signal molecules in the area. In this study, we compared the bacterial signal molecules of 50 nosocomial Acinetobacter baumannii strain and 20 A. baumannii strain isolated from soil. The signal molecules were detected by the biosensor bacteria (Chromobacterium violaceum 026, Agrobacterium tumefaciens A136, and Agrobacterium tumefaciens NTL1) and their separation was determined by thin-layer chromatography. As a result, it has been found that soil-borne isolates can produce 3-oxo-C8-AHL and C8-AHL, whereas nosocomial-derived isolates can produce long-chain signals such as C10-AHL, C12-AHL, C14-AHL and C16-AHL. According to these results, it is possible to understand that these signal molecules are found in the infection caused by A. baumannii. The inhibition of this signaling molecules in a communication could use to prevent multiple antibiotic resistance of these bacteria.

  8. Structure determination of LpxA from the lipopolysaccharide-synthesis pathway of Acinetobacter baumannii

    International Nuclear Information System (INIS)

    Badger, John; Chie-Leon, Barbara; Logan, Cheyenne; Sridhar, Vandana; Sankaran, Banumathi; Zwart, Peter H.; Nienaber, Vicki

    2012-01-01

    Crystal structures of the LpxA protein from A. baumannii were solved in apo forms that were suitable for structure-based antibacterial drug discovery. Acinetobacter baumannii is a Gram-negative pathogenic bacterium which is resistant to most currently available antibiotics and that poses a significant health threat to hospital patients. LpxA is a key enzyme in the biosynthetic pathway of the lipopolysaccharides that are components of the bacterial outer membrane. It is a potential target for antibacterial agents that might be used to fight A. baumannii infections. This paper describes the structure determination of the apo form of LpxA in space groups P2 1 2 1 2 1 and P6 3 . These crystal forms contained three and one protein molecules in the asymmetric unit and diffracted to 1.8 and 1.4 Å resolution, respectively. A comparison of the conformations of the independent protein monomers within and between the two crystal asymmetric units revealed very little structural variation across this set of structures. In the P6 3 crystal form the enzymatic site is exposed and is available for the introduction of small molecules of the type used in fragment-based drug discovery and structure-based lead optimization

  9. [Lower respiratory tract infections related to Stenotrophomonas maltophilia and Acinetobacter baumannii].

    Science.gov (United States)

    Baranzelli, A; Wallyn, F; Nseir, S

    2013-10-01

    Stenotrophomonas maltophilia and Acinetobacter baumannii are both non-fermenting ubiquitous Gram-negative bacilli. The incidence of lower respiratory tract infections related to these microorganisms is increasing, especially in intensive care units. Their capacity to acquire resistance against several antimicrobials is challenging for clinicians and microbiologists. Despite their low virulence, these pathogens are responsible for colonization and infection in patients with comorbidities, immunosuppression, and critically ill patients. S. maltophilia and A. baumannii are mainly identified in nosocomial infections: ventilator-associated pneumonia, bacteremia and surgical wound infection. Infections related to these microorganism are associated with high mortality and morbidity. Trimethoprime-sulfamethoxazole and carbapenem are the first line treatment for infections related to S. maltophilia and A. baumannii respectively. However, the increasing rate of resistance against these agents results in difficulties in treating patients with infections related to these pathogens. New antimicrobial agents and further randomized studies are needed to improve the treatment of these infections. Prevention of spared of these multidrug-resistant bacteria is mandatory, including hand-hygiene, environment cleaning, and limited usage of large spectrum antibiotics. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  10. Discrimination of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex species by Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Sousa, C; Silva, L; Grosso, F; Nemec, A; Lopes, J; Peixe, L

    2014-08-01

    The main goal of this work was to assess the ability of Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) to discriminate between the species of the Acinetobacter calcoaceticus-Acinetobacter baumannii (Acb) complex, i.e. A. baumannii, A. nosocomialis, A. pittii, A. calcoaceticus, genomic species "Between 1 and 3" and genomic species "Close to 13TU". A total of 122 clinical isolates of the Acb complex previously identified by rpoB sequencing were studied. FTIR-ATR spectra was analysed by partial least squares discriminant analysis (PLSDA) and the model scores were presented in a dendrogram form. This spectroscopic technique proved to be effective in the discrimination of the Acb complex species, with sensitivities from 90 to 100%. Moreover, a flowchart aiming to help with species identification was developed and tested with 100% correct predictions for A. baumannii, A. nosocomialis and A. pittii test isolates. This rapid, low cost and environmentally friendly technique proved to be a reliable alternative for the identification of these closely related Acinetobacter species that share many clinical and epidemiological characteristics and are often difficult to distinguish. Its validation towards application on a routine basis could revolutionise high-throughput bacterial identification.

  11. Clinical features and epidemiology of Acinetobacter baumannii colonization and infection in Spanish hospitals.

    Science.gov (United States)

    Rodríguez-Baño, Jesús; Cisneros, Jose M; Fernández-Cuenca, Felipe; Ribera, Anna; Vila, Jordi; Pascual, Alvaro; Martínez-Martínez, Luis; Bou, German; Pachón, Jerónimo

    2004-10-01

    To investigate the clinical features and the epidemiology of Acinetobacter baumannii in Spanish hospitals. Prospective multicenter cohort study. Twenty-seven general hospitals and one paraplegic center in Spain. All cases of A. baumannii colonization or infection detected by clinical samples during November 2000 were included. Isolates were identified using phenotypic and genotypic methods. The molecular relatedness of the isolates was assessed by pulsed-field gel electrophoresis. Twenty-five (89%) of the hospitals had 221 cases (pooled rate in general hospitals, 0.39 case per 1,000 patient-days; range, 0 to 1.17). The rate was highest in intensive care units (ICUs). Only 3 cases were pediatric. The mean age of the patients in the general hospitals was 63 years; 69% had a chronic underlying disease and 80% had previously received antimicrobial treatment. Fifty-three percent of the patients had an infection (respiratory tract, 51%; surgical site, 16%; and urinary tract, 11%). Crude mortality was higher in infected than in colonized patients (27% vs 10%; relative risk, 1.56; 95% confidence interval, 1.2 to 2.0; P = .003). Molecular analysis disclosed 79 different clones. In most hospitals, a predominant epidemic clone coexisted with other sporadic clones. Imipenem resistance was present in 39% of the hospitals. A. baumannii was present in most participating Spanish hospitals (particularly in ICUs) with different rates among them. The organisms mainly affected predisposed patients; half of them were only colonized. Epidemic and sporadic clones coexisted in many centers.

  12. Epidemiology of Carbapenemase-Producing Enterobacteriaceae and Acinetobacter baumannii in Mediterranean Countries

    Directory of Open Access Journals (Sweden)

    Nassima Djahmi

    2014-01-01

    Full Text Available The emergence and global spread of carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii are of great concern to health services worldwide. These β-lactamases hydrolyse almost all β-lactams, are plasmid-encoded, and are easily transferable among bacterial species. They are mostly of the KPC, VIM, IMP, NDM, and OXA-48 types. Their current extensive spread worldwide in Enterobacteriaceae is an important source of concern. Infections caused by these bacteria have limited treatment options and have been associated with high mortality rates. Carbapenemase producers are mainly identified among Klebsiella pneumoniae, Escherichia coli, and A. baumannii and still mostly in hospital settings and rarely in the community. The Mediterranean region is of interest due to a great diversity and population mixing. The prevalence of carbapenemases is particularly high, with this area constituting one of the most important reservoirs. The types of carbapenemase vary among countries, partially depending on the population exchange relationship between the regions and the possible reservoirs of each carbapenemase. This review described the epidemiology of carbapenemases produced by enterobacteria and A. baumannii in this part of the world highlighting the worrisome situation and the need to screen and detect these enzymes to prevent and control their dissemination.

  13. Emergence and clonal dissemination of carbapenem-hydrolysing OXA-58-producing Acinetobacter baumannii isolates in Bolivia.

    Science.gov (United States)

    Sevillano, Elena; Fernández, Elena; Bustamante, Zulema; Zabalaga, Silvia; Rosales, Ikerne; Umaran, Adelaida; Gallego, Lucía

    2012-01-01

    Acinetobacter baumannii is an emerging multidrug-resistant pathogen and very little information is available regarding its imipenem resistance in Latin American countries such as Bolivia. This study investigated the antimicrobial resistance profile of 46 clinical strains from different hospitals in Cochabamba, Bolivia, from March 2008 to July 2009, and the presence of carbapenemases as a mechanism of resistance to imipenem. Isolates were obtained from 46 patients (one isolate per patient; 30 males,16 females) with an age range of 1 day to 84 years, and were collected from different sample types, the majority from respiratory tract infections (17) and wounds (13). Resistance to imipenem was detected in 15 isolates collected from different hospitals of the city. These isolates grouped into the same genotype, named A, and were resistant to all antibiotics tested including imipenem, with susceptibility only to colistin. Experiments to detect carbapenemases revealed the presence of the OXA-58 carbapenemase. Further analysis revealed the location of the bla(OXA-58) gene on a 40 kb plasmid. To our knowledge, this is the first report of carbapenem resistance in A. baumannii isolates from Bolivia that is conferred by the OXA-58 carbapenemase. The presence of this gene in a multidrug-resistant clone and its location within a plasmid is of great concern with regard to the spread of carbapenem-resistant A. baumannii in the hospital environment in Bolivia.

  14. Molecular Characterization of Reduced Susceptibility to Biocides in Clinical Isolates of Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Fei Lin

    2017-09-01

    Full Text Available Active efflux is regarded as a common mechanism for antibiotic and biocide resistance. However, the role of many drug efflux pumps in biocide resistance in Acinetobacter baumannii remains unknown. Using biocide-resistant A. baumannii clinical isolates, we investigated the incidence of 11 known/putative antimicrobial resistance efflux pump genes (adeB, adeG, adeJ, adeT1, adeT2, amvA, abeD, abeM, qacE, qacEΔ1, and aceI and triclosan target gene fabI through PCR and DNA sequencing. Reverse transcriptase quantitative PCR was conducted to assess the correlation between the efflux pump gene expression and the reduced susceptibility to triclosan or chlorhexidine. The A. baumannii isolates displayed high levels of reduced susceptibility to triclosan, chlorhexidine, benzalkonium, hydrogen peroxide, and ethanol. Most tested isolates were resistant to multiple antibiotics. Efflux resistance genes were widely distributed and generally expressed in A. baumannii. Although no clear relation was established between efflux pump gene expression and antibiotic resistance or reduced biocide susceptibility, triclosan non-susceptible isolates displayed relatively increased expression of adeB and adeJ whereas chlorhexidine non-susceptible isolates had increased abeM and fabI gene expression. Increased expression of adeJ and abeM was also demonstrated in multiple antibiotic resistant isolates. Exposure of isolates to subinhibitory concentrations of triclosan or chlorhexidine induced gene expression of adeB, adeG, adeJ and fabI, and adeB, respectively. A point mutation in FabI, Gly95Ser, was observed in only one triclosan-resistant isolate. Multiple sequence types with the major clone complex, CC92, were identified in high level triclosan-resistant isolates. Overall, this study showed the high prevalence of antibiotic and biocide resistance as well as the complexity of intertwined resistance mechanisms in clinical isolates of A. baumannii, which highlights the

  15. Dissemination of carbapenem-resistant Acinetobacter baumannii in patients with burn injuries.

    Science.gov (United States)

    Shoja, Saeed; Moosavian, Mojtaba; Rostami, Soodabeh; Farahani, Abbas; Peymani, Amir; Ahmadi, Khadijeh; Ebrahimifard, Nasim

    2017-04-01

    Carbapenem-resistant Acinetobacter baumannii has emerged as an important cause of infection in burn patients. This study aimed to characterize the antimicrobial susceptibility pattern, determine the prevalence of oxacillinase and metallo-beta-lactamase (MBL) genes, and type the A. baumannii isolates obtained from burn patients. During a 1-year period, a total of 40 nonduplicated isolates of A. baumannii were obtained from burn patients who were hospitalized in the Taleghani Burn Hospital in Ahvaz, in the southwest of Iran. Testing for antimicrobial susceptibility was carried out by disk diffusion and E-test. To screen MBL production, a double disk synergy and MBL E-test were performed. The presence of bla OXA-23-like , bla OXA-24-like , bla OXA-51-like and bla OXA-58-like , bla VIM , bla IMP and bla SPM , and bla NDM was sought by polymerase chain reaction (PCR). Repetitive extragenic palindromic sequence-based PCR was carried out for determination of isolates clonality. Overall, 92.5% of isolates were carbapenem-resistant. Polymyxin B, colistin, and ampicillin-sulbactam were the most effective agents in vitro, with a susceptibility rate of 100%, 97.5%, and 72.5%, respectively. According to the double disk synergy and E-test, 55.6% and 97.3% of isolates were MBL producers, respectively. Furthermore, 70% of isolates harbored bla OXA-23-like and 20% were positive for bla OXA-24-like. However, no encoding genes were detected for bla VIM , bla IMP and bla SPM , bla NDM , and bla OXA-58-like . Repetitive extragenic palindromic sequence-based PCR revealed that carbapenem-resistant isolates belonged to four clones, including A, B, C, and D; the predominant clones were B and C. The rate of carbapenem resistance was high, and it appeared that bla OXA-23-like and bla OXA-24-like contributed to the carbapenem resistance of A. baumannii isolates. This result suggests that the two predominant clones of A. baumannii were spread among burn patients. In order to prevent future

  16. Acinetobacter baumannii Isolated from Lebanese Patients: Phenotypes and Genotypes of Resistance, Clonality, and Determinants of Pathogenicity.

    Science.gov (United States)

    Dahdouh, Elias; Hajjar, Micheline; Suarez, Monica; Daoud, Ziad

    2016-01-01

    Introduction: Acinetobacter baumannii is a nosocomial pathogen that usually affects critically ill patients. High mortality rates have been associated with MDR A. baumannii infections. Carbapenem resistance among these isolates is increasing worldwide and is associated with certain International Clones (ICs) and oxacillinases (OXAs). Moreover, this organism possesses a wide range of virulence factors, whose expression is not yet fully understood. In this study, clinical A. baumannii isolates are characterized in terms of antibiotic resistance, mechanisms of carbapenem resistance, clonality, and virulence. Materials and Methods: A. baumannii clinical isolates ( n = 90) where obtained from a tertiary care center in Beirut, Lebanon. API 20NE strips in addition to the amplification of bla OXA-51-like were used for identification. Antibiotic susceptibility testing by disk diffusion was then performed in addition to PCRs for the detection of the most commonly disseminated carbapenemases. Clonality was determined by tri-locus PCR typing and doubling times were determined for isolates with varying susceptibility profiles. Biofilm formation, hemolysis, siderophore production, proteolytic activity, and surface motility was then determined for all the isolates. Statistical analysis was then performed for the determination of associations. Results and Discussion: 81 (90%) of the isolates were resistant to carbapenems. These high rates are similar to other multi-center studies in the country suggesting the need of intervention on a national level. 74 (91.3%) of the carbapenem resistant isolates harbored bla OXA-23-like including two that also harbored bla OXA-24-like . 88.9% of the A. baumannii isolates pertained to ICII and three other international clones were detected, showing the wide dissemination of clones into geographically distinct locations. Virulence profiles were highly diverse and no specific pattern was observed. Nevertheless, an association between motility

  17. Polyvinylpyrrolidone-Capped Silver Nanoparticle Inhibits Infection of Carbapenem-Resistant Strain of Acinetobacter baumannii in the Human Pulmonary Epithelial Cell

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    Vishvanath Tiwari

    2017-08-01

    Full Text Available Acinetobacter baumannii, an opportunistic ESKAPE pathogen, causes respiratory and urinary tract infections. Its prevalence increases gradually in the clinical setup. Pathogenicity of Acinetobacter is significantly influenced by its ability to infect and survive in human pulmonary cells. Therefore, it is important to study the infection of A. baumannii in human pulmonary host cell (A-549, monitoring surface interacting and internalized bacteria. It was found that during infection of A. baumannii, about 40% bacteria adhered to A-549, whereas 20% got internalized inside pulmonary cell and induces threefold increase in the reactive oxygen species production. We have synthesized polyvinylpyrrolidone (PVP-capped AgNPs using chemical methods and tested its efficacy against carbapenem-resistant strain of A. baumannii. PVP-capped silver nanoparticles (PVP-AgNPs (30 µM have shown antibacterial activity against carbapenem-resistant strain of A. baumannii and this concentration does not have any cytotoxic effect on the human pulmonary cell line (IC50 is 130 µM. Similarly, PVP-AgNPs treatment decreases 80% viability of intracellular bacteria, decreases adherence of A. baumannii to A-549 (40 to 2.2%, and decreases intracellular concentration (20 to 1.3% of A. baumannii. This concludes that PVP-AgNPs can be developed as a substitute for carbapenem to control the infection caused by carbapenem-resistant A. baumannii.

  18. Does antimicrobial usage before meningitis lead to a higher risk of adult postsurgical Acinetobacter baumannii meningitis than that of Enterobacteriaceae meningitis?

    Science.gov (United States)

    Demiraslan, Hayati; Ulutabanca, Halil; Ercal, Baris Derya; Metan, Gokhan; Alp, Emine

    2016-12-01

    Acinetobacter baumannii and Enterobacteriaceae are two pathogens responsible for postneurosurgical meningitis. The aim of this retrospective study was to evaluate the factors that influenced the outcomes in patients with postneurosurgical meningitis caused by A. baumannii and Enterobacteriaceae. Patients with post-surgical meningitis were identified from infection control committee charts between 2007 and 2015. Subjects over 16 years old who had positive cerebral spinal fluid cultures for A. baumannii or Enterobacteriaceae were enrolled in the study. Clinical and laboratory data for 30 patients with A. baumannii meningitis were compared with those of 12 patients with Enterobacteriaceae meningitis. The mean age of patients was 51.9 years and 57.1% were male. Eleven patients had comorbidities, the most common being diabetes mellitus. Most patients were due to intracranial haemorrhage (78.6%). The rate of the patients who received an appropriate antimicrobial therapy was 35.7%, and the crude mortality rate was 64.3%. In univariate analysis, previous antibiotic use, an infection before meningitis and mechanical ventilation had an increased risk of A. baumannii meningitis. Moreover, intrathecal antimicrobial use, inappropriate empirical antimicrobial use, antimicrobial resistance and alanine aminotransferase elevation were significantly higher in patients with A. baumannii meningitis than in those with Enterobacteriaceae meningitis. Antimicrobial use before meningitis (8.84 times) and mechanical ventilation (7.28 times) resulted in an increased risk of A. baumannii meningitis. None of the results affected 30-day mortality. Avoidance of unnecessarily prolonged antimicrobial usage may help to prevent a selection of A. baumannii.

  19. Emergence of New Delhi metallo-beta-lactamase 1 and other carbapenemase-producing Acinetobacter calcoaceticus-baumannii complex among patients in hospitals in Ha Noi, Viet Nam

    NARCIS (Netherlands)

    Tran, D.N.; Tran, H.H.; Matsui, M.; Suzuki, M.; Suzuki, S.; Shibayama, K.; Pham, T.D.; Phuong, T.T. Van; Dang, D.A.; Trinh, H.S.; Loan, C.T.; Nga, L.T.; Doorn, H.R. van; Wertheim, H.F.L.

    2017-01-01

    Acinetobacter baumannii is an important cause of multidrug-resistant hospital acquired infections in the world. Here, we investigate the presence of NDM-1 and other carbapenemases among carbapenem-resistant A. baumannii isolated between August 2010 and December 2014 from three large hospitals in

  20. RT-PCR and statistical analyses of adeABC expression in clinical isolates of Acinetobacter calcoaceticus-Acinetobacter baumannii complex.

    Science.gov (United States)

    Ruzin, Alexey; Immermann, Frederick W; Bradford, Patricia A

    2010-06-01

    The relationship between expression of adeABC and minimal inhibitory concentration (MIC) of tigecycline was investigated by RT-PCR and statistical analyses in a population of 106 clinical isolates (MIC range, 0.0313-16 microg/ml) of Acinetobacter calcoaceticus-Acinetobacter baumannii complex. There was a statistically significant linear relationship (p calcoaceticus-A. baumannii complex.

  1. A 5-year Surveillance Study on Antimicrobial Resistance of Acinetobacter baumannii Clinical Isolates from a Tertiary Greek Hospital.

    Science.gov (United States)

    Maraki, Sofia; Mantadakis, Elpis; Mavromanolaki, Viktoria Eirini; Kofteridis, Diamantis P; Samonis, George

    2016-09-01

    Acinetobacter baumannii has emerged as a major cause of nosocomial outbreaks. It is particularly associated with nosocomial pneumonia and bloodstream infections in immunocompromised and debilitated patients with serious underlying pathologies. Over the last two decades, a remarkable rise in the rates of multidrug resistance to most antimicrobial agents that are active against A. baumannii has been noted worldwide. We evaluated the rates of antimicrobial resistance and changes in resistance over a 5-year period (2010-2014) in A. baumannii strains isolated from hospitalized patients in a tertiary Greek hospital. Identification of A. baumannii was performed by standard biochemical methods and the Vitek 2 automated system, which was also used for susceptibility testing against 18 antibiotics: ampicillin/sulbactam, ticarcillin, ticarcillin/clavulanic acid, piperacillin, piperacillin/tazobactam, cefotaxime, ceftazidime, cefepime, imipenem, meropenem, gentamicin, amikacin, tobramycin, ciprofloxacin, tetracycline, tigecycline, trimethoprim/sulfamethoxazole, and colistin. Interpretation of susceptibility results was based on the Clinical and Laboratory Standards Institute criteria, except for tigecycline, for which the Food and Drug Administration breakpoints were applied. Multidrug resistance was defined as resistance to ≥3 classes of antimicrobial agents. Overall 914 clinical isolates of A. baumannii were recovered from the intensive care unit (ICU) (n = 493), and medical (n = 252) and surgical (n = 169) wards. Only 4.9% of these isolates were fully susceptible to the antimicrobials tested, while 92.89% of them were multidrug resistant (MDR), i.e., resistant to ≥3 classes of antibiotics. ICU isolates were the most resistant followed by isolates from surgical and medical wards. The most effective antimicrobial agents were, in descending order: colistin, amikacin, trimethoprim/sulfamethoxazole, tigecycline, and tobramycin. Nevertheless, with the exception of colistin

  2. The Expanding Universe: Dark Energy

    Energy Technology Data Exchange (ETDEWEB)

    Lincoln, Don [Fermilab; Nord, Brian [Fermilab

    2014-09-01

    In 1998, observations of distant supernovae led physicists that not only was the universe expanding, but the expansion was speeding up. In this article, we describe the evidence for an expanding universe and describe what physicists and cosmologists have learned in the intervening years. The target audience for this article is high school physics teachers and college physics professors at teaching institutions.

  3. Transmission electron microscopic morphological study and flow cytometric viability assessment of Acinetobacter baumannii susceptible to Musca domestica cecropin.

    Science.gov (United States)

    Gui, Shuiqing; Li, Rongjiang; Feng, Yongwen; Wang, Sanming

    2014-01-01

    Multidrug-resistant (MDR) Acinetobacter baumannii infections are difficult to treat owing to the extremely limited armamentarium. Expectations about antimicrobial peptides' use as new powerful antibacterial agents have been raised on the basis of their unique mechanism of action. Musca domestica cecropin (Mdc), a novel antimicrobial peptide from the larvae of Housefly (Musca domestica), has potently active against Gram-positive and Gram-negative bacteria standard strain. Here we evaluated the antibacterial activity of Mdc against clinical isolates of MDR-A. baumannii and elucidate the related antibacterial mechanisms. The minimal inhibitory concentration (MIC) of Mdc was 4 μg/mL. Bactericidal kinetics of Mdc revealed rapid killing of A. baumannii (30 min). Flow cytometry using viability stain demonstrated that Mdc causes A. baumannii membrane permeabilization in a concentration- and time-dependent process, which correlates with the bactericidal action. Moreover, transmission electron microscopic (TEM) examination showed that Mdc is capable of disrupting the membrane of bacterial cells, resulting in efflux of essential cytoplasmic components. Overall, Mdc could be a promising antibacterial agent for MDR-A. baumannii infections.

  4. Transmission Electron Microscopic Morphological Study and Flow Cytometric Viability Assessment of Acinetobacter baumannii Susceptible to Musca domestica cecropin

    Directory of Open Access Journals (Sweden)

    Shuiqing Gui

    2014-01-01

    Full Text Available Multidrug-resistant (MDR Acinetobacter baumannii infections are difficult to treat owing to the extremely limited armamentarium. Expectations about antimicrobial peptides' use as new powerful antibacterial agents have been raised on the basis of their unique mechanism of action. Musca domestica cecropin (Mdc, a novel antimicrobial peptide from the larvae of Housefly (Musca domestica, has potently active against Gram-positive and Gram-negative bacteria standard strain. Here we evaluated the antibacterial activity of Mdc against clinical isolates of MDR-A. baumannii and elucidate the related antibacterial mechanisms. The minimal inhibitory concentration (MIC of Mdc was 4 μg/mL. Bactericidal kinetics of Mdc revealed rapid killing of A. baumannii (30 min. Flow cytometry using viability stain demonstrated that Mdc causes A. baumannii membrane permeabilization in a concentration- and time-dependent process, which correlates with the bactericidal action. Moreover, transmission electron microscopic (TEM examination showed that Mdc is capable of disrupting the membrane of bacterial cells, resulting in efflux of essential cytoplasmic components. Overall, Mdc could be a promising antibacterial agent for MDR-A. baumannii infections.

  5. In vitro activities of carbapenems in combination with amikacin, colistin, or fosfomycin against carbapenem-resistant Acinetobacter baumannii clinical isolates.

    Science.gov (United States)

    Singkham-In, Uthaibhorn; Chatsuwan, Tanittha

    2018-01-31

    Carbapenem-resistant Acinetobacter baumannii clinical isolates (n=23) were investigated for carbapenem resistance mechanisms and in vitro activities of carbapenems in combination with amikacin, colistin, or fosfomycin. Major carbapenem resistance mechanism was OXA-23 production. The vast majority of these isolates were OXA-23-producing A. baumannii ST195 and ST542, followed by novel STs, ST1417, and ST1423. The interuption of carO by a novel insertion sequence, ISAba40, was found in two isolates. The combinations of imipenem and fosfomycin, meropenem and amikacin, imipenem and amikacin, and imipenem and colistin were synergistic against carbapenem-resistant A. baumannii by 65.2%, 46.2%, 30.8%, and 17.4%, respectively. Surprisingly, the combination of imipenem and fosfomycin was the most effective in this study against A. baumannii, which is intrinsically resistant to fosfomycin. Imipenem and fosfomycin inhibit cell wall synthesis; therefore, fosfomycin may be an adjuvant and enhance the inhibition of cell wall synthesis of carbapenem-resistant A. baumannii when combined with imipenem. Copyright © 2018. Published by Elsevier Inc.

  6. Persistence of Multidrug-Resistant Acinetobacter baumannii Isolates Harboring blaOXA-23 and bap for 5 Years.

    Science.gov (United States)

    Sung, Ji Youn; Koo, Sun Hoe; Kim, Semi; Kwon, Gye Cheol

    2016-08-28

    The emergence and dissemination of carbapenemase-producing Acinetobacter baumannii isolates have been reported worldwide, and A. baumannii isolates harboring blaOXA-23 are often resistant to various antimicrobial agents. Antimicrobial resistance can be particularly strong for biofilm-forming A. baumannii isolates. We investigated the genetic basis for carbapenem resistance and biofilm-forming ability of multidrug-resistant (MDR) clinical isolates. Ninety-two MDR A. baumannii isolates were collected from one university hospital located in the Chungcheong area of Korea over a 5-year period. Multiplex PCR and DNA sequencing were performed to characterize carbapenemase and bap genes. Clonal characteristics were analyzed using REP-PCR. In addition, imaging and quantification of biofilms were performed using a crystal violet assay. All 92 MDR A. baumannii isolates involved in our study contained the blaOXA-23 and bap genes. The average absorbance of biomass in Bap-producing strains was much greater than that in non-Bap-producing strains. In our study, only three REP-PCR types were found, and the isolates showing type A or type B were found more than 60 times among unique patients during the 5 years of surveillance. These results suggest that the isolates have persisted and colonized for 5 years, and biofilm formation ability has been responsible for their persistence and colonization.

  7. Antibacterial Effects of Origanum vulgare Essence Against Multidrug-Resistant Acinetobacter baumannii Isolated From Selected Hospitals of Tehran, Iran

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    Saghi

    2015-02-01

    Full Text Available Background Infection due to Acinetobacter baumannii has become a significant challenge to modern healthcare systems. The rapid emergence and global dissemination of A. baumannii as a major nosocomial pathogen is remarkable and it demonstrates its successful adaptation to the 21st century hospital environment. Recent studies have discussed about essential oil of Origanum vulgare against a range of bacteria, including various species of Staphylococcus, Pseudomonas, Bacillus and Escherichia coli. Objectives The present study aimed to investigate the inhibitory effects O. vulgare essence against multidrug-resistant (MDR strains of A. baumannii from selected hospitals in Tehran, Iran. Materials and Methods This oil was obtained using the hydrodistillation method and analyzed by gas chromatography mass spectrography (GC/MS. The antimicrobial activity against MDR isolates was achieved using disc diffusion method and macro-broth dilution assay. Results Analysis of the essential oil revealed the presence of pulegone (68.59% piperitone (7.8%, piperitenone (7.8%, 1, 8-cineole (1.3%, and carvacrol (1.6% as the major components. The results showed a significant activity against MDR A. baumannii with inhibition zones and minimal inhibitory concentration values in the ranges of 7-15 mm and 20-35 µL/mL respectively. Conclusions This investigation showed that the essence oil of O. vulgare had a potent antimicrobial activity against MDR A. baumannii. Further research is required to evaluate the practical values of therapeutic applications.

  8. Antibacterial Activity of Pinus pinaster Bark Extract and its Components Against Multidrug-resistant Clinical Isolates of Acinetobacter baumannii

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    Mirna Ćurković-Perica

    2015-07-01

    Full Text Available The aim of this research was to test the antibacterial activity of Pinus pinaster aqueous bark extract (PABE and its basic components against multidrug-resistant isolates of Acinetobacter baumannii belonging to European clone I and II, isolated previously from the clinical outbreaks. The minimum bactericidal concentration of PABE against both clones of A. baumannii was 200 mg ml–1, while lower concentrations showed high antibacterial activity. After 24 h of treatment with 100, 50 or 10 mg ml–1 of extract, the reduction in the number of A. baumannii isolates belonging to European clone I and II was 85.8 ± 2.5 %, 78.5 ± 1.1 %, 66.3 ± 2.5 % and 90.2 ± 1.7 %, 78.6 ± 1.2 %, 69.8 ± 0.7 %, respectively. Several basic components: caffeic acid, catechin, epicatechin, gallic acid and vanillin, detected in the extract by high performance liquid chromatography, contributed to the antibacterial activity of the extract against both clones of A. baumannii. However, the antibacterial activity of extract was higher than that of each tested basic component suggesting that proanthocyanidins, which were present in quite a large amount in the extract, might have also contributed to the activity of the extract. Antibacterial activity of PABE against A. baumannii reveals that complex and inexpensive natural product might be useful in combat against naturally competent bacteria that easily acquire resistance against antibiotics.

  9. Current trends of drug resistance patterns of Acinetobacter baumannii infection in blood transfusion-dependent thalassemia patients

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    Suhail Ahmed Almani

    2017-01-01

    Full Text Available Objective: The present study aimed to evaluate the current trends of drug resistance patterns of Acinetobacter baumannii infection in blood transfusion-dependent thalassemia patients. Study Design: This study was a cross sectional study, conducted at the Liaquat University of Medical and Health Sciences, Jamshoro/Hyderabad, Sindh, Pakistan from October 2014 to January 2016. Subjects and Methods: Of 921 blood samples, A. baumannii strains were isolated from 100 blood samples. Blood samples were processed for the isolation, identification, and drugs sensitivity as per the Clinical and Laboratory Standards Institute. A. baumannii strains were identified by microbiological methods and Gram's staining. API 20 E kit (Biomeriuex, USA was also used for identification. Data were analyzed on Statisti × 8.1 (USA. Results: Mean ± standard deviation age was 11.5 ± 2.8 years. Nearly 70% were male and 30% were female (P = 0.0001. Of 921 blood transfusion-dependent thalassemia patients, 100 (10.8% patients showed growth of A. baumannii. Drug resistance was observed against the ceftazidime, cefixime, cefepime, imipenem, meropenem, amikacin, minocycline, tigecycline, and tazocin except for the colistin. Conclusion: The present study reports drug-resistant A. baumannii in blood transfusion-dependent thalassemia patients. National multicenter studies are recommended to estimate the size of the problem.

  10. Current Trends of Drug Resistance Patterns of Acinetobacter baumannii Infection in Blood Transfusion-dependent Thalassemia Patients.

    Science.gov (United States)

    Almani, Suhail Ahmed; Naseer, Ali; Maheshwari, Sanjay Kumar; Maroof, Pir; Naseer, Raza; Khoharo, Haji Khan

    2017-01-01

    The present study aimed to evaluate the current trends of drug resistance patterns of Acinetobacter baumannii infection in blood transfusion-dependent thalassemia patients. This study was a cross sectional study, conducted at the Liaquat University of Medical and Health Sciences, Jamshoro/Hyderabad, Sindh, Pakistan from October 2014 to January 2016. Of 921 blood samples, A. baumannii strains were isolated from 100 blood samples. Blood samples were processed for the isolation, identification, and drugs sensitivity as per the Clinical and Laboratory Standards Institute. A. baumannii strains were identified by microbiological methods and Gram's staining. API 20 E kit (Biomeriuex, USA) was also used for identification. Data were analyzed on Statisti × 8.1 (USA). Mean ± standard deviation age was 11.5 ± 2.8 years. Nearly 70% were male and 30% were female ( P = 0.0001). Of 921 blood transfusion-dependent thalassemia patients, 100 (10.8%) patients showed growth of A. baumannii . Drug resistance was observed against the ceftazidime, cefixime, cefepime, imipenem, meropenem, amikacin, minocycline, tigecycline, and tazocin except for the colistin. The present study reports drug-resistant A. baumannii in blood transfusion-dependent thalassemia patients. National multicenter studies are recommended to estimate the size of the problem.

  11. Detection of OXA-Type Carbapenemase Genes in Acinetobacter baumannii Isolates from Nosocomial Infections in Isfahan Hospitals, Iran

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    Vajihe Karbasizade

    2016-02-01

    Full Text Available "> Background: Acinetobacter baumannii as one of the causes of nosocomial infections has becomeresistant to almost all antimicrobial agents. The emergence of resistance to carbapenems, one ofthe last drugs on the shelf, is the major concern about A. baumannii antimicrobial resistance.Resistance to carbapenems is mediated by production of class B and D carbapenemases. The aimof this study was to detect the resistance genes including blaOXA-23, 24, 51, and 58 in A. baumanniiisolates from nosocomial infections in Isfahan hospitals.Methods: A total number of 456 clinical specimens were collected from nosocomial infections andevaluated in order to isolate A. baumannii strains. After identification of the isolates, the antibioticsensitivity to carbapenems was assessed using disk diffusion method. The resistance genes of blaOXA-23, 24, 51, and 58 were detected by multiplex PCR method.Results: Fifty A. baumannii isolates were isolated from clinical specimens. Fifty two percent ofthe isolates showed phenotypic resistance to the carbapenems (imipenem and meropenem.According to PCR results, 88% of resistant isolates had ≥1 blaOXA gene. The frequency of resistantisolates bearing blaOXA-23, blaOXA-24 and blaOXA-58 were 77%, 38% and 15% respectively.Conclusions: This study showed the high frequency of carbapenem resistance genes among A.baumannii isolates. Therefore, adopting an appropriate strategy to confine the spreading of thesestrains and also implementing new treatment regimens are necessary.

  12. Emergence of a multiresistant KPC-3 and VIM-1 carbapenemase-producing Escherichia coli strain in Spain.

    Science.gov (United States)

    Porres-Osante, Nerea; Azcona-Gutiérrez, Jose Manuel; Rojo-Bezares, Beatriz; Undabeitia, Esther; Torres, Carmen; Sáenz, Yolanda

    2014-07-01

    To characterize the mechanisms involved in carbapenem resistance, as well as the genetic elements supporting their mobilization, in a multidrug-resistant Escherichia coli isolate. The E. coli isolate was obtained from a patient with fatal urinary sepsis. Antimicrobial susceptibility testing was performed by the disc diffusion and agar dilution methods. The E. coli molecular type and phylogroup were determined using multilocus sequence typing and the triple PCR technique, respectively. PCR and sequencing were used for virulence and resistance genotype characterization. Plasmid content and gene location were analysed by S1-PFGE, I-Ceu1-PFGE and hybridization experiments. Transformation assays were performed. The E. coli strain, typed as ST448 and phylogroup B1, was resistant to all tested antibiotics except fosfomycin, tigecycline and tetracycline. The following resistance and virulence genetic structures were obtained: ISKpn7 + bla(KPC-3) + ISKpn6 linked to Tn4401; tnpR + aac(6')-Ib'-9 + aadA1 + bla(OXA-9) + tnpR + bla(TEM-1a) + tnpB + strB + strA + sul2; intI1 + bla(VIM-1) + aac(6')-Ib' + aphA15 + aadA1 + catB2 + qacEΔ1-sul1 + orf5; ISEcp1 + bla(CMY-2); IS26 + bla(SHV-12); aph(3')-I; aac(3)-IV; floR; catA; and fimA. Mutations in the ampC promoter (-18, -1 and +58) and substitutions in the GyrA (Ser-83→Leu and Asp-87→Asn) and ParC (Ser-80→Ile) proteins were observed. IncFII (ST2), IncA/C and ColE(TP) plasmids of 145.5, 87 and bla(VIM-1) gene was located in a non-typeable plasmid of >300 kb, and the bla(KPC-3) gene in the 145.5 kb IncFII plasmid. Transformant strains carried the IncFII and ColE(TP) plasmids, and the bla(KPC-3), bla(TEM-1a), bla(OXA-9), aadA1, aac(6')-Ib'-9, aac(3)-IV and floR genes. This is the first report of the co-production of KPC-3, VIM-1, SHV-12, OXA-9 and CMY-2 in a unique clinical multiresistant E. coli isolate. The dissemination of these genes on mobile

  13. Antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model: implications for prophylaxis and treatment of combat-related wound infections.

    Science.gov (United States)

    Zhang, Yunsong; Zhu, Yingbo; Gupta, Asheesh; Huang, Yingying; Murray, Clinton K; Vrahas, Mark S; Sherwood, Margaret E; Baer, David G; Hamblin, Michael R; Dai, Tianhong

    2014-06-15

    In this study, we investigated the utility of antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model. A bioluminescent clinical isolate of multidrug-resistant A. baumannii was obtained. The susceptibility of A. baumannii to blue light (415 nm)-inactivation was compared in vitro to that of human keratinocytes. Repeated cycles of sublethal inactivation of bacterial by blue light were performed to investigate the potential resistance development of A. baumannii to blue light. A mouse model of third degree burn infected with A. baumannii was developed. A single exposure of blue light was initiated 30 minutes after bacterial inoculation to inactivate A. baumannii in mouse burns. It was found that the multidrug-resistant A. baumannii strain was significantly more susceptible than keratinocytes to blue light inactivation. Transmission electron microscopy revealed blue light-induced ultrastructural damage in A. baumannii cells. Fluorescence spectroscopy suggested that endogenous porphyrins exist in A. baumannii cells. Blue light at an exposure of 55.8 J/cm(2) significantly reduced the bacterial burden in mouse burns. No resistance development to blue light inactivation was observed in A. baumannii after 10 cycles of sublethal inactivation of bacteria. No significant DNA damage was detected in mouse skin by means of a skin TUNEL assay after a blue light exposure of 195 J/cm(2). © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Targeted therapy against multi-resistant bacteria in leukemic and hematopoietic stem cell transplant recipients: guidelines of the 4th European Conference on Infections in Leukemia (ECIL-4, 2011)

    NARCIS (Netherlands)

    Averbuch, D.; Cordonnier, C.; Livermore, D.M.; Mikulska, M.; Orasch, C.; Viscoli, C.; Gyssens, I.C.J.; Kern, W.V.; Klyasova, G.; Marchetti, O.; Engelhard, D.; Akova, M.; Ecil, a.j.v.o.E.E.I.E.E.; Eln, .

    2013-01-01

    The detection of multi-resistant bacterial pathogens, particularly those to carbapenemases, in leukemic and stem cell transplant patients forces the use of old or non-conventional agents as the only remaining treatment options. These include colistin/polymyxin B, tigecycline, fosfomycin and various

  15. Characteriz ation of integrons and associated gene cassettes in Acinetobacter baumannii strains isolated from intensive care unit in Tehran, Iran

    Directory of Open Access Journals (Sweden)

    Hossein Goudarzi

    2016-09-01

    Full Text Available Objective: To determine the antimicrobial susceptibility patterns, the frequency of integrons and associated gene cassettes in Acinetobacter baumannii (A. baumannii strains isolated from selected hospital intensive care units. Methods: During a ten-month period, 120 A. baumannii isolates were studied. The resistance rates to different classes of antimicrobial agents were determined. PCR was used to detect different types of integrons and associated gene cassettes. Results: The resistance rates to the majority of antibiotics tested were found to be between 39.3% and 99.1%. No isolate was observed to be resistant to colistin and polymyxin B. The rate of extensive drug-resistance among these clinical isolates was 62.5%. The prevalence of class 1 and 2 integrons was found to be 74.1% and 12.5%, respectively. Seven different gene cassettes (ampC, aacA4-catB8, ISAba1-blaOXA-23-GES-14, aadA2-cm1A6-GES-14-qacF, VIM-25-GES-24-qacF, dfrA5-ISAba1-blaOXA-51-blaOXA-40 and aadA2-GES-11-IMP-1 were observed in Class 1 integron-carrying strains. Three gene cassettes (IMP-4, VIM-2-VEB-aacA4 and dfrA2-sat-2-aadA4 were detected in class 2 integron-bearing A. baumannii strains. Conclusions: A high prevalence of integron was described among multidrug resistant A. baumannii in the hospital. The findings highlighted the need for continuous surveillance in order to prevent dissemination of multidrug resistance among A. baumannii strains in Iran.

  16. Molecular Epidemiology and Clinical Impact of Acinetobacter calcoaceticus-baumannii Complex in a Belgian Burn Wound Center.

    Directory of Open Access Journals (Sweden)

    Daniel De Vos

    Full Text Available Multidrug resistant Acinetobacter baumannii and its closely related species A. pittii and A. nosocomialis, all members of the Acinetobacter calcoaceticus-baumannii (Acb complex, are a major cause of hospital acquired infection. In the burn wound center of the Queen Astrid military hospital in Brussels, 48 patients were colonized or infected with Acb complex over a 52-month period. We report the molecular epidemiology of these organisms, their clinical impact and infection control measures taken. A representative set of 157 Acb complex isolates was analyzed using repetitive sequence-based PCR (rep-PCR (DiversiLab and a multiplex PCR targeting OXA-51-like and OXA-23-like genes. We identified 31 rep-PCR genotypes (strains. Representatives of each rep-type were identified to species by rpoB sequence analysis: 13 types to A. baumannii, 10 to A. pittii, and 3 to A. nosocomialis. It was assumed that isolates that belonged to the same rep-type also belonged to the same species. Thus, 83.4% of all isolates were identified to A. baumannii, 9.6% to A. pittii and 4.5% to A. nosocomialis. We observed 12 extensively drug resistant Acb strains (10 A. baumannii and 2 A. nosocomialis, all carbapenem-non-susceptible/colistin-susceptible and imported into the burn wound center through patients injured in North Africa. The two most prevalent rep-types 12 and 13 harbored an OXA-23-like gene. Multilocus sequence typing allocated them to clonal complex 1 corresponding to EU (international clone I. Both strains caused consecutive outbreaks, interspersed with periods of apparent eradication. Patients infected with carbapenem resistant A. baumannii were successfully treated with colistin/rifampicin. Extensive infection control measures were required to eradicate the organisms. Acinetobacter infection and colonization was not associated with increased attributable mortality.

  17. Epidemiology of extensive drug resistant Acinetobacter baumannii (XDRAB) at Security Forces Hospital (SFH) in Kingdom of Saudi Arabia (KSA).

    Science.gov (United States)

    Al-Obeid, Suleiman; Jabri, Lina; Al-Agamy, Mohammad; Al-Omari, Awad; Shibl, Atef

    2015-06-01

    Extensively drug-resistant Acinetobacter baumannii (XDRAB) became a worldwide nosocomial threat. The aim of this study was to assess the epidemiology and to evaluate the prevalence of carbapenem-resistant A. baumannii (CRAB). We also discuss therapeutic options for the management of their infections. Antibiotic susceptibility was determined in 506, 510 and 936 duplicate isolates of A. baumannii isolated in 2006, 2009 and 2012, respectively. In 2012, 12 unique XDRAB strains were isolated from patients with serious ventilator-associated pneumonia (VAP). Susceptibility tests were performed using the microdilution method according to Clinical and Laboratory Standards Institute (CLSI) recommendations. MICs were determined in triplicate by E-test according to the manufacturer's recommendations. Susceptible and multidrug-resistant A. baumannii (MDRAB) strains were detected using CHROMagar Acinetobacter medium. Carbapenem resistant A. baumannii was investigated for carbapenemase production by the modified Hodge test (MHT) and by multiplex PCR. A Synergy test was performed using the E-test method. Considering years 2006, 2009 and 2012, the susceptibilities to meropenem and imipenem were 64-81.2%, 34.5-45.3%, and 8.3-11%, respectively. Concerning the 12 XDRAB strains, all isolates were susceptible to colistin and resistant to meropenem and imipenem. Culture on CHROMagar Acinetobacter confirmed that all are MDRAB. The gene profiles detected in PCR assays showed that all the strains possess OXA-51.Out of the 12 isolates, 11 possess the oxa-23 gene and one harbours the gene 24/40. A good synergistic effect was detected between colistin and tigecycline. In this study, A. baumannii susceptibility to carbapenems showed a drastic reduction and represents a major epidemiological concern. The main carbapenem resistance mechanism is mediated by class D-OXA-type enzymes (oxa-23 and oxa-24/40) with Carbapenemase activity. Therapeutic options are exceedingly limited, relying on polymyxin

  18. Disruption of tetR type regulator adeN by mobile genetic element confers elevated virulence in Acinetobacter baumannii.

    Science.gov (United States)

    Saranathan, Rajagopalan; Pagal, Sudhakar; Sawant, Ajit R; Tomar, Archana; Madhangi, M; Sah, Suresh; Satti, Annapurna; Arunkumar, K P; Prashanth, K

    2017-10-03

    Acinetobacter baumannii is an important human pathogen and considered as a major threat due to its extreme drug resistance. In this study, the genome of a hyper-virulent MDR strain PKAB07 of A. baumannii isolated from an Indian patient was sequenced and analyzed to understand its mechanisms of virulence, resistance and evolution. Comparative genome analysis of PKAB07 revealed virulence and resistance related genes scattered throughout the genome, instead of being organized as an island, indicating the highly mosaic nature of the genome. Many intermittent horizontal gene transfer events, insertion sequence (IS) element insertions identified were augmenting resistance machinery and elevating the SNP densities in A. baumannii eventually aiding in their swift evolution. ISAba1, the most widely distributed insertion sequence in A. baumannii was found in multiple sites in PKAB07. Out of many ISAba1 insertions, we identified novel insertions in 9 different genes wherein insertional inactivation of adeN (tetR type regulator) was significant. To assess the significance of this disruption in A. baumannii, adeN mutant and complement strains were constructed in A. baumannii ATCC 17978 strain and studied. Biofilm levels were abrogated in the adeN knockout when compared with the wild type and complemented strain of adeN knockout. Virulence of the adeN knockout mutant strain was observed to be high, which was validated by in vitro experiments and Galleria mellonella infection model. The overexpression of adeJ, a major component of AdeIJK efflux pump observed in adeN knockout strain could be the possible reason for the elevated virulence in adeN mutant and PKB07 strain. Knocking out of adeN in ATCC strain led to increased resistance and virulence at par with the PKAB07. Disruption of tetR type regulator adeN by ISAba1 consequently has led to elevated virulence in this pathogen.

  19. OXA-23 and ISAba1-OXA-66 class D β-lactamases in Acinetobacter baumannii isolates from companion animals.

    Science.gov (United States)

    Ewers, Christa; Klotz, Peter; Leidner, Ursula; Stamm, Ivonne; Prenger-Berninghoff, Ellen; Göttig, Stephan; Semmler, Torsten; Scheufen, Sandra

    2017-01-01

    Acinetobacter baumannii is recognised as a major pathogen of nosocomial infections that frequently show resistance to last-resort antimicrobials. To investigate whether A. baumannii from companion animals harbour carbapenem resistance mechanisms, 223 clinical isolates obtained from veterinary clinics between 2000 and 2013 in Germany were screened for carbapenem-non-susceptibility employing meropenem-containing Mueller-Hinton agar plates. Minimum inhibitory concentration (MIC) data were obtained using the VITEK ® 2 system. Assignment to international clones (ICs) was done by multiplex PCR or repetitive sequence-based PCR employing the DiversiLab system. Clonality was studied using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Genes encoding carbapenemases and aminoglycoside-modifying enzymes were detected by PCR. In three samples from dogs, carbapenem-resistant A. baumannii carrying the bla OXA-23 gene on plasmids and located on transposon Tn2008 were identified. The isolates belonged to sequence type ST1 P (clonal complex CC1/IC1/pulsotype II) and ST10 P (CC10/IC8/pulsotype IV) according to the Pasteur MLST scheme, and to ST231 Ox (CC109) and ST585 Ox (CC447) following the Oxford scheme. Insertion sequence ISAba1 was identified upstream of bla OXA-66 in 58 A. baumannii isolates. MLST referred them to ST2 P (CC2/IC2/pulsotypes I and III), ST208 Ox , ST350 Ox and ST556 Ox (all CC118), respectively. PFGE suggested nosocomial spread of these highly related strains, which frequently demonstrated a multidrug-resistant phenotype, in one veterinary clinic. These data show that A. baumannii from companion animals reveal resistance determinants and clonal lineages of strains globally emerging in humans. This suggests an interspecies transmission and warrants molecular surveillance of A. baumannii in veterinary clinics to mitigate its further spread. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights

  20. Epidemiological characterization of Acinetobacter baumannii bloodstream isolates from a Chinese Burn Institute: A three-year study.

    Science.gov (United States)

    Huang, Guangtao; Yin, Supeng; Xiang, Lijuan; Gong, Yali; Sun, Kedai; Luo, Xiaoqiang; Zhang, Cheng; Yang, Zichen; Deng, Liuyang; Jiang, Bei; Jin, Shouguang; Chen, Jing; Peng, Yizhi

    2016-11-01

    Acinetobacter baumannii infection is a serious threat to burn patients. Bacteremia due to A. baumannii is becoming the most common cause of mortality following burn. However, the epidemiology of A. baumannii causing burn-related bloodstream infections has rarely been reported. We retrospectively collected 81 A. baumannii isolates from the bloodstream of burn patients over a three-year period. Antibiotic susceptibility tests, the prevalence of antibiotic-resistant genes and sequence typing (ST) were conducted to characterize these strains. Most of the isolates showed an extensive drug-resistant phenotype. The resistance frequencies to imipenem and meropenem were 94% and 91%, respectively. The blaOXA-23-like gene, AmpC, IS-AmpC, PER and SIM are the five most prevalent resistant genes, and their prevalence rates are 93% (75/81), 86% (70/81), 73% (59/81), 73% (59/81) and 52% (42/81), respectively. The 81 isolates were grouped into 10 known and 18 unknown ST types, with ST368 (38%) being the most prevalent. Except for ST457 and four new types (STn2, STn6, STn11 and STn14), the remaining 23 ST types belonged to one clonal complex 92, which is most common among clinical isolate in China. The above results indicated that ST368 isolates possessing both the blaOXA-23-like gene and ampC gene were the main culprits of the increasing nosocomial A. baumannii infection in this study. More attention should be paid to monitoring the molecular epidemiology of A. baumannii isolates from burn patients to prevent further distribution. Such information may help clinicians with therapeutic decisions and infection control in the Burns Institute. Copyright © 2016. Published by Elsevier Ltd.

  1. Molecular Epidemiology and Clinical Impact of Acinetobacter calcoaceticus-baumannii Complex in a Belgian Burn Wound Center

    Science.gov (United States)

    Bilocq, Florence; Jennes, Serge; Verbeken, Gilbert; Rose, Thomas; Keersebilck, Elkana; Bosmans, Petra; Pieters, Thierry; Hing, Mony; Heuninckx, Walter; De Pauw, Frank; Soentjens, Patrick; Merabishvili, Maia; Deschaght, Pieter; Vaneechoutte, Mario; Bogaerts, Pierre; Glupczynski, Youri; Pot, Bruno; van der Reijden, Tanny J.; Dijkshoorn, Lenie

    2016-01-01

    Multidrug resistant Acinetobacter baumannii and its closely related species A. pittii and A. nosocomialis, all members of the Acinetobacter calcoaceticus-baumannii (Acb) complex, are a major cause of hospital acquired infection. In the burn wound center of the Queen Astrid military hospital in Brussels, 48 patients were colonized or infected with Acb complex over a 52-month period. We report the molecular epidemiology of these organisms, their clinical impact and infection control measures taken. A representative set of 157 Acb complex isolates was analyzed using repetitive sequence-based PCR (rep-PCR) (DiversiLab) and a multiplex PCR targeting OXA-51-like and OXA-23-like genes. We identified 31 rep-PCR genotypes (strains). Representatives of each rep-type were identified to species by rpoB sequence analysis: 13 types to A. baumannii, 10 to A. pittii, and 3 to A. nosocomialis. It was assumed that isolates that belonged to the same rep-type also belonged to the same species. Thus, 83.4% of all isolates were identified to A. baumannii, 9.6% to A. pittii and 4.5% to A. nosocomialis. We observed 12 extensively drug resistant Acb strains (10 A. baumannii and 2 A. nosocomialis), all carbapenem-non-susceptible/colistin-susceptible and imported into the burn wound center through patients injured in North Africa. The two most prevalent rep-types 12 and 13 harbored an OXA-23-like gene. Multilocus sequence typing allocated them to clonal complex 1 corresponding to EU (international) clone I. Both strains caused consecutive outbreaks, interspersed with periods of apparent eradication. Patients infected with carbapenem resistant A. baumannii were successfully treated with colistin/rifampicin. Extensive infection control measures were required to eradicate the organisms. Acinetobacter infection and colonization was not associated with increased attributable mortality. PMID:27223476

  2. Molecular Epidemiology and Clinical Impact of Acinetobacter calcoaceticus-baumannii Complex in a Belgian Burn Wound Center.

    Science.gov (United States)

    De Vos, Daniel; Pirnay, Jean-Paul; Bilocq, Florence; Jennes, Serge; Verbeken, Gilbert; Rose, Thomas; Keersebilck, Elkana; Bosmans, Petra; Pieters, Thierry; Hing, Mony; Heuninckx, Walter; De Pauw, Frank; Soentjens, Patrick; Merabishvili, Maia; Deschaght, Pieter; Vaneechoutte, Mario; Bogaerts, Pierre; Glupczynski, Youri; Pot, Bruno; van der Reijden, Tanny J; Dijkshoorn, Lenie

    2016-01-01

    Multidrug resistant Acinetobacter baumannii and its closely related species A. pittii and A. nosocomialis, all members of the Acinetobacter calcoaceticus-baumannii (Acb) complex, are a major cause of hospital acquired infection. In the burn wound center of the Queen Astrid military hospital in Brussels, 48 patients were colonized or infected with Acb complex over a 52-month period. We report the molecular epidemiology of these organisms, their clinical impact and infection control measures taken. A representative set of 157 Acb complex isolates was analyzed using repetitive sequence-based PCR (rep-PCR) (DiversiLab) and a multiplex PCR targeting OXA-51-like and OXA-23-like genes. We identified 31 rep-PCR genotypes (strains). Representatives of each rep-type were identified to species by rpoB sequence analysis: 13 types to A. baumannii, 10 to A. pittii, and 3 to A. nosocomialis. It was assumed that isolates that belonged to the same rep-type also belonged to the same species. Thus, 83.4% of all isolates were identified to A. baumannii, 9.6% to A. pittii and 4.5% to A. nosocomialis. We observed 12 extensively drug resistant Acb strains (10 A. baumannii and 2 A. nosocomialis), all carbapenem-non-susceptible/colistin-susceptible and imported into the burn wound center through patients injured in North Africa. The two most prevalent rep-types 12 and 13 harbored an OXA-23-like gene. Multilocus sequence typing allocated them to clonal complex 1 corresponding to EU (international) clone I. Both strains caused consecutive outbreaks, interspersed with periods of apparent eradication. Patients infected with carbapenem resistant A. baumannii were successfully treated with colistin/rifampicin. Extensive infection control measures were required to eradicate the organisms. Acinetobacter infection and colonization was not associated with increased attributable mortality.

  3. Immunization with lipopolysaccharide-deficient whole cells provides protective immunity in an experimental mouse model of Acinetobacter baumannii infection.

    Directory of Open Access Journals (Sweden)

    Meritxell García-Quintanilla

    Full Text Available The increasing clinical importance of infections caused by multidrug resistant Acinetobacter baumannii warrants the development of novel approaches for prevention and treatment. In this context, vaccination of certain patient populations may contribute to reducing the morbidity and mortality caused by this pathogen. Vaccines against Gram-negative bacteria based on inactivated bacterial cells are highly immunogenic and have been shown to produce protective immunity against a number of bacterial species. However, the high endotoxin levels present in these vaccines due to the presence of lipopolysaccharide complicates their use in human vaccination. In the present study, we used a laboratory-derived strain of A. baumannii that completely lacks lipopolysaccharide due to a mutation in the lpxD gene (IB010, one of the genes involved in the first steps of lipopolysaccharide biosynthesis, for vaccination. We demonstrate that IB010 has greatly reduced endotoxin content (<1.0 endotoxin unit/106 cells compared to wild type cells. Immunization with formalin inactivated IB010 produced a robust antibody response consisting of both IgG1 and IgG2c subtypes. Mice immunized with IB010 had significantly lower post-infection tissue bacterial loads and significantly lower serum levels of the pro-inflammatory cytokines IL-1β, TNF-α and IL-6 compared to control mice in a mouse model of disseminated A. baumannii infection. Importantly, immunized mice were protected from infection with the ATCC 19606 strain and an A. baumannii clinical isolate. These data suggest that immunization with inactivated A. baumannii whole cells deficient in lipopolysaccharide could serve as the basis for a vaccine for the prevention of infection caused by A. baumannii.

  4. Antimicrobial activity of novel 4H-4-oxoquinolizine compounds against extensively drug-resistant Acinetobacter baumannii strains.

    Science.gov (United States)

    Na, Seok Hyeon; Jeon, Hyejin; Kim, Yoo Jeong; Kwon, Hyo Il; Selasi, Gati Noble; Nicholas, Asiimwe; Yun, Chang-Soo; Lee, Sang Ho; Lee, Je Chul

    2017-01-01

    The aim of this study was to screen lead compounds exhibiting potent in vitro antimicrobial activity against multidrug-resistant (MDR) Acinetobacter baumannii strains from a library of chemical compounds. In a high-throughput screening analysis of 7520 compounds representative of 340,000 small molecules, two 4H-4-oxoquinolizine compounds were the most active against A. baumannii ATCC 17978. Subsequent selection and analysis of 70 4H-4-oxoquinolizine compounds revealed that the top 7 compounds were extremely active against extensively drug-resistant (XDR) A. baumannii isolates. These compounds commonly carried a 1-cyclopropyl-7-fluoro-4-oxo-4H-quinolizine-3-carboxylic acid core structure but had different C-8 and/or C-9 moieties. Minimum inhibitory concentrations (MICs) of the seven compounds against fluoroquinolone-resistant A. baumannii isolates were found to be in the range of 0.02-1.70 µg/mL regardless of the mutation types in the quinolone resistance-determining region (QRDR) of GyrA and ParC. Cytotoxicity of the seven compounds was observed in HeLa and U937 cells at a concentration of 50 µg/mL, which was >32.5- to 119-fold higher than the MIC 90 for A. baumannii isolates. In conclusion, novel 4H-4-oxoquinolizine compounds represent a promising scaffold on which to develop antimicrobial agents against drug-resistant A. baumannii strains. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  5. Transposons and integrons in colistin-resistant clones of Klebsiella pneumoniae and Acinetobacter baumannii with epidemic or sporadic behaviour.

    Science.gov (United States)

    Arduino, Sonia M; Quiroga, María Paula; Ramírez, María Soledad; Merkier, Andrea Karina; Errecalde, Laura; Di Martino, Ana; Smayevsky, Jorgelina; Kaufman, Sara; Centrón, Daniela

    2012-10-01

    Multiple transposons, integrons and carbapenemases were found in Klebsiella pneumoniae colistin-resistant isolates as well as a genomic resistance island of the AbaR type in Acinetobacter baumannii colistin-resistant isolates from different hospitals from Buenos Aires City. PFGE analysis showed a polyclonal dissemination of antimicrobial resistance mechanisms among K. pneumoniae isolates, while in A. baumannii isolates the epidemic clone 1 from South America was found. Resistance determinants associated with horizontal gene transfer are contributing to the evolution to pandrug resistance in both epidemic and sporadic clones.

  6. Community-acquired carbapenem-resistant Acinetobacter baumannii urinary tract infection just after marriage in a renal transplant recipient.

    Science.gov (United States)

    Solak, Y; Atalay, H; Turkmen, K; Biyik, Z; Genc, N; Yeksan, M

    2011-12-01

    Urinary tract infection (UTI) is common in renal transplant recipients and may worsen allograft and patient survival. Many risk factors such as age, female gender, immunosuppression, comorbidity, deceased-donor kidney transplantation, and uretheral catheterization are involved in development of UTI. Acinetobacter baumannii has rarely been reported as a causative agent for development of UTI. Here, we present an unusual case of a renal transplant recipient who developed community-acquired carbapenem-resistent A. baumannii UTI. © 2011 John Wiley & Sons A/S.

  7. Acinetobacter baumannii and A. pittii clinical isolates lack adherence and cytotoxicity to lung epithelial cells in vitro.

    Science.gov (United States)

    Lázaro-Díez, María; Navascués-Lejarza, Teresa; Remuzgo-Martínez, Sara; Navas, Jesús; Icardo, José Manuel; Acosta, Felix; Martínez-Martínez, Luis; Ramos-Vivas, José

    2016-09-01

    The molecular and genetic basis of Acinetobacter baumannii and Acinetobacter pittii virulence remains poorly understood, and there is still lack of knowledge in host cell response to these bacteria. In this study, we have used eleven clinical Acinetobacter strains (A. baumannii n = 5; A. pittii n = 6) to unravel bacterial adherence, invasion and cytotoxicity to human lung epithelial cells. Our results showed that adherence to epithelial cells by Acinetobacter strains is scarce and cellular invasion was not truly detected. In addition, all Acinetobacter strains failed to induce any cytotoxic effect on A549 cells. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  8. GigA and GigB are Master Regulators of Antibiotic Resistance, Stress Responses, and Virulence in Acinetobacter baumannii.

    Science.gov (United States)

    Gebhardt, Michael J; Shuman, Howard A

    2017-05-15

    A critical component of bacterial pathogenesis is the ability of an invading organism to sense and adapt to the harsh environment imposed by the host's immune system. This is especially important for opportunistic pathogens, such as Acinetobacter baumannii , a nutritionally versatile environmental organism that has recently gained attention as a life-threatening human pathogen. The emergence of A. baumannii is closely linked to antibiotic resistance, and many contemporary isolates are multidrug resistant (MDR). Unlike many other MDR pathogens, the molecular mechanisms underlying A. baumannii pathogenesis remain largely unknown. We report here the characterization of two recently identified virulence determinants, GigA and GigB, which comprise a signal transduction pathway required for surviving environmental stresses, causing infection and antibiotic resistance. Through transcriptome analysis, we show that GigA and GigB coordinately regulate the expression of many genes and are required for generating an appropriate transcriptional response during antibiotic exposure. Genetic and biochemical data demonstrate a direct link between GigA and GigB and the nitrogen phosphotransferase system (PTS Ntr ), establishing a novel connection between a novel stress response module and a well-conserved metabolic-sensing pathway. Based on the results presented here, we propose that GigA and GigB are master regulators of a global stress response in A. baumannii , and coupling this pathway with the PTS Ntr allows A. baumannii to integrate cellular metabolic status with external environmental cues. IMPORTANCE Opportunistic pathogens, including Acinetobacter baumannii , encounter many harsh environments during the infection cycle, including antibiotic exposure and the hostile environment within a host. While the development of antibiotic resistance in A. baumannii has been well studied, how this organism senses and responds to environmental cues remain largely unknown. Herein, we

  9. Ventilator-associated pneumonia due to extensive drug-resistant Acinetobacter baumannii: risk factors, clinical features, and outcomes.

    Science.gov (United States)

    Özgür, Eylem Sercan; Horasan, Elif Sahin; Karaca, Kerem; Ersöz, Gülden; Naycı Atış, Sibel; Kaya, Ali

    2014-02-01

    Acinetobacter baumannii is characterized by a rapid development of resistance to the commonly used antimicrobial agents. We investigated the risk factors, clinical features, and outcomes in ventilator-associated pneumonia (VAP) caused by extensive drug-resistant Acinetobacter baumannii (XDRAB). Clinical parameters and overall in-hospital mortality rates were compared between the VAP with and without XDRAB infection groups. This study showed that VAP caused by XDRAB was not associated with in-hospital mortality. However, it was related to high Simplified Acute Physiology Score II scores and increasing durations of hospital stays. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  10. Characterisation of recently emerged multiple antibiotic-resistant Salmonella enterica serovar typhimurium DT104 and other multiresistant phage types from Danish pig herds

    DEFF Research Database (Denmark)

    Baggesen, Dorte Lau; Aarestrup, Frank Møller

    1998-01-01

    electrophoresis (PFGE) using the restriction enzyme Xba I, Overall, 66 per cent of the 670 isolates were sensitive to all the antimicrobial agents tested. Eleven isolates of S typhimurium were resistant to ampicillin, streptomycin and tetracycline and also resistant to other antibiotics in different resistance...... enterica serovar typhimurium (S typhimurium) isolates resistant to ampicillin, streptomycin and tetracycline and three isolates of S typhimurium DT104, two from 1994 and one from 1995, were further tested for resistance against chloramphenicol and sulphonamide and analysed by pulsed-field gel...... patterns. Seven different multiresistant clones were identified, The most common clones were four isolates of DT104 and three isolates of DT193, TWO Of the three S typhimurium DT104 from 1994 and 1995 were sensitive to all the antimicrobials tested whereas the remaining isolate from 1994 was resistant...

  11. Characterisation of recently emerged multiple antibiotic-resistant Salmonella enterica serovar typhimurium DT104 and other multiresistant phage types from Danish pig herds

    DEFF Research Database (Denmark)

    Baggesen, Dorte Lau; Aarestrup, Frank Møller

    1998-01-01

    electrophoresis (PFGE) using the restriction enzyme Xba I, Overall, 66 per cent of the 670 isolates were sensitive to all the antimicrobial agents tested. Eleven isolates of S typhimurium were resistant to ampicillin, streptomycin and tetracycline and also resistant to other antibiotics in different resistance...... patterns. Seven different multiresistant clones were identified, The most common clones were four isolates of DT104 and three isolates of DT193, TWO Of the three S typhimurium DT104 from 1994 and 1995 were sensitive to all the antimicrobials tested whereas the remaining isolate from 1994 was resistant......A total of 670 isolates of Salmonella enterica were isolated from Danish pig herds, phage typed and tested for susceptibility to amoxycillin + clavulanate, ampicillin, colistin, enrofloxacin, gentamicin, neomycin, spectinomycin, streptomycin, tetracyclines, and trimethoprim + sulphadiazine. S...

  12. Bactericidal Activity and Synergy Studies of Peptide AP-CECT7121 Against Multi-resistant Bacteria Isolated from Human and Animal Soft Tissue Infections.

    Science.gov (United States)

    Delpech, Gastón; Bistoletti, Mariana; Ceci, Mónica; Lissarrague, Sabina; Bruni, Sergio Sánchez; Sparo, Mónica

    2017-09-01

    AP-CECT7121 is an antimicrobial peptide, produced by Enterococcus faecalis CECT7121, with bactericidal activity against Gram-positive bacteria. The aim of this study was to evaluate the bactericidal activity of AP-CECT7121, alone and with gentamicin, against multi-resistant bacteria isolated from human and animals with soft tissue infections. During the period 2014-2015, bacterial strains producing human and animal soft tissue infections were studied. Samples from patients attended at a general hospital and cattle from four dairies in the Province of Buenos Aires (Argentina) were included. Twenty-two methicillin-resistant Staphylococcus aureus (11, human blood samples; 11, cow milk) and five vancomycin-resistant Ent. faecium strains isolated from four mastitic dairy cows were tested. AP-CECT7121 (12 mg/L) potency was assessed by time-kill curves alone or with sub-inhibitory concentrations of gentamicin. All staphylococcal strains were susceptible to gentamicin; enterococci did not show high-level gentamicin resistance. Colony counts were carried out at 0, 2, 4, 8, and 24 h of incubation. AP-CECT7121 showed bactericidal activity against all the enterococcal strains. In addition, AP-CECT7121 had a bactericidal effect on most staphylococci (16/22). Early AP-CECT7121/gentamicin synergy (4-8 h) for all staphylococci was detected. At 24 h, synergy (19/22) and indifference (3/22) were observed. Synergy with gentamicin was detected for staphylococci. AP-CECT7121 constitutes an attractive candidate for its use as a natural therapeutic tool for the treatment of infections produced by multi-resistant Staph. aureus and vancomycin-resistant Ent. faecium isolated from humans and animals.

  13. Colistin/daptomycin: an unconventional antimicrobial combination synergistic in vitro against multidrug-resistant Acinetobacter baumannii.

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    Galani, Irene; Orlandou, Konstantina; Moraitou, Helen; Petrikkos, George; Souli, Maria

    2014-04-01

    The in vitro activity of the combination colistin/daptomycin was evaluated against multidrug-resistant Acinetobacter baumannii clinical isolates. Clonal relationships were assessed by pulsed-field gel electrophoresis. The following synergy studies were undertaken: (i) daptomycin MICs were determined by E-test on Mueller-Hinton agar plates supplemented with a subinhibitory concentration of colistin; and (ii) time-kill methodology using tubes containing an inoculum of 5×10(5)CFU/mL and subinhibitory concentrations of each antibiotic alone or in combination subcultured at 0, 5 and 24h for colony counting. Synergy was defined as ≥2log10CFU/mL decrease of viable colonies compared with colistin alone. Ten colistin-susceptible and four colistin-resistant A. baumannii isolates were tested. Isolates were assigned to nine different clonal types. Enhanced in vitro activity of the combination was detected only against colistin-susceptible isolates; using plates supplemented with colistin, the daptomycin MIC was reduced by 4- to 128-fold. From a total of 30 isolate-concentration combinations in time-kill studies, a synergistic interaction was detected in 16 (53.3%). The combination exhibited synergy against 8 and 12 of these combinations at 5h and 24h, respectively. No antagonism was detected. Colistin alone was bactericidal against two colistin-susceptible isolates at 24h, whereas the combination was bactericidal against 9 colistin-susceptible isolates at 24h. Against all colistin-resistant isolates, the combination exhibited a static effect and indifference in time-kill studies. Potent in vitro synergistic interactions between colistin and daptomycin provide evidence that this unorthodox combination may be beneficial in the treatment of colistin-susceptible multidrug-resistant A. baumannii. Copyright © 2014. Published by Elsevier B.V.

  14. Distinct Genetic Diversity of Carbapenem-Resistant Acinetobacter baumannii from Colombian Hospitals.

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    Correa, Adriana; Del Campo, Rosa; Escandón-Vargas, Kevin; Perenguez, Marcela; Rodríguez-Baños, Mercedes; Hernández-Gómez, Cristhian; Pallares, Christian; Perez, Federico; Arias, Cesar A; Cantón, Rafael; Villegas, María V

    The global success of multidrug-resistant Acinetobacter baumannii has been associated with the dissemination of a high-risk clone designated clonal complex (CC) 92 B (Bartual scheme)/CC2 P (Pasteur scheme), which is the most frequent genetic lineage in European, Asian, and North American carbapenem-resistant Acinetobacter isolates. In these isolates, carbapenem resistance is mainly mediated by β-lactamases encoded by bla OXA-23-like , bla OXA-24-like , bla OXA-51-like , and/or bla OXA-58-like genes. In this study, we characterized the population genetics of 121 carbapenem-resistant A. baumannii complex isolates recovered from 14 hospitals in seven cities in Colombia (2008-2010). Multiplex PCR was used to detect bla OXA-23-like , bla OXA-24-like , bla OXA-51-like , and bla OXA-58-like genes. Molecular typing was performed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). PCR showed that 118 (97.5%) of the isolates were positive for both bla OXA-23-like and bla OXA-51-like genes, and three other isolates were only positive for bla OXA-51-like . PFGE identified 18 different pulsotypes, while MLST identified 11 different sequence types (STs), seven of which had not been previously described in Acinetobacter. None of the STs found in this study was associated with CC92 B /CC2 P . The most widespread STs in our isolates belonged to ST636 and their single-locus variants ST121/ST124/ST634 (CC636 B ) followed by STs belonging to CC110 B . Our observations suggest a wide distribution of diverse A. baumannii complex clones containing bla OXA-23-like in Colombian hospitals (especially CC636 B and CC110 B ) that differ from the high-risk clones commonly found in other regions of the world, indicating a distinct molecular epidemiology of carbapenem-resistant Acinetobacter spp. in Colombia.

  15. Wide distribution of carbapenem resistant Acinetobacter baumannii in burns patients in Iran.

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    Farshadzadeh, Zahra; Hashemi, Farhad B; Rahimi, Sara; Pourakbari, Babak; Esmaeili, Davoud; Haghighi, Mohammad A; Majidpour, Ali; Shojaa, Saeed; Rahmani, Maryam; Gharesi, Samira; Aziemzadeh, Masoud; Bahador, Abbas

    2015-01-01

    Antimicrobial resistance in carbapenem non-susceptible Acinetobacter baumannii (CNSAb) is a major public health concern globally. This study determined the antibiotic resistance and molecular epidemiology of CNSAb isolates from a referral burn center in Tehran, Iran. Sixty-nine CNSAb isolates were tested for susceptibility to antimicrobial agents using the E test methodology. Multiple locus variable number tandem repeat analysis (MLVA), Multilocus sequence typing (MLST) and multiplex PCR were performed. PCR assays tested for ambler classes A, B, and D β-lactamases. Detection of ISAba1, characterization of integrons, and biofilm formation were investigated. Fifty-three (77%) isolates revealed XDR phenotypes. High prevalence of bla OXA-23-like (88%) and bla PER-1 (54%) were detected. ISAba1 was detected upstream of bla ADC, bla OXA-23-like and bla OXA51-like genes in, 97, 42, and 26% of isolates, respectively. Thirty-one (45%) isolates were assigned to international clone (IC) variants. MLVA identified 56 distinct types with six clusters and 53 singleton genotypes. Forty previously known MLST sequence types forming 5 clonal complexes were identified. The Class 1 integron (class 1 integrons) gene was identified in 84% of the isolates. The most prevalent (33%) cassette combination was aacA4-catB8-aadA1. The IC variants were predominant in the A. baumannii lineage with the ability to form strong biofilms. The XDR-CNSAb from burned patients in Iran is resistant to various antimicrobials, including tigecycline. This study shows wide genetic diversity in CNSAb. Integrating the new Iranian A. baumannii IC variants into the epidemiologic clonal and susceptibility profile databases can help effective global control measures against the XDR-CNSAb pandemic.

  16. Extracellular proteome of a highly invasive multidrug-resistant clinical strain of Acinetobacter baumannii.

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    Mendez, Jose Antonio; Soares, Nelson C; Mateos, Jesús; Gayoso, Carmen; Rumbo, Carlos; Aranda, Jesús; Tomas, Maria; Bou, Germán

    2012-12-07

    The study of the extracellular proteomes of pathogenic bacteria is essential for gaining insights into the mechanisms of pathogenesis and for the identification of virulence factors. Through the use of different proteomic approaches, namely Nano-LC and 2DE combined with MALDI-TOF/TOF, we have characterized the extracellular proteome of a highly invasive, multidrug-resistant strain of A. baumannii (clone AbH12O-A2). This study focused on two main protein fractions of the extracellular proteome: proteins that are exported by outer membrane vesicles (OMVs) and freely soluble extracellular proteins (FSEPs) present in the culture medium of A. baumannii. Herein, a total of 179 nonredundant proteins were identified in the OMV protein fraction and a total of 148 nonredundant proteins were identified in FSEP fraction. Of the OMV proteins, 39 were associated with pathogenesis and virulence, including proteins associated with attachment to host cells (e.g., CsuE, CsuB, CsuA/B) and specialized secretion systems for delivery of virulence factors (e.g., P. pilus assembly and FilF), whereas the FSEP fraction possesses extracellular enzymes with degradative activity, such as alkaline metalloprotease. Furthermore, among the FSEP we have detected at least 18 proteins with a known role in oxidative stress response (e.g., catalase, thioredoxin, oxidoreductase, superoxide dismutase). Further assays demonstrated that in the presence of FSEPs, bacterial cells withstand much higher concentrations of H2O2 showing higher survival rate (approximately 2.5 fold) against macrophages. In this study we have identified an unprecedented number of novel extracellular proteins of A. baumannii and we provide insight into their potential role in relevant processes such as oxidative stress response and defense against macrophage attack.

  17. ACTIVITY OF THYME OIL (OLEUM THYMI) AGAINST MULTIDRUG-RESISTANT ACINETOBACTER BAUMANNII AND PSEUDOMONAS AERUGINOSA.

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    Trojanowska, Danuta; Paluchowska, Paulina; Soja, Łukasz; Budak, Alicja

    2016-07-01

    Almost as soon as antibiotics were introduced to treat infectious diseases, it could be observed that bacteria were able to develop resistance against them. Currently, multidrug-resistant strains are being isolated mainly in the hospital environment. These are primarily non-fermenting Gram-negative bacilli, which exhibit both natural and acquired resistance to multiple antibiotics and disinfectants rendering them difficult to eradicate. The development of new, effective and safe substances that prevent troublesome infections is greatly needed to provide alternative therapeutic options for patients. There is increasing interest in drugs of natural origin, including essential oils. It is of particular interest that, although active against many bacterial strains, they do not contribute to antibacterial resistance against their components. The aim of our study was to evaluate the in vino antibacterial activity of thyme oil against multidrug-resistant strains of A. baumannii and P. aeriginosa using the disc diffusion and macrodilution methods. The strains were isolated from patients hospitalized in the years 2013-2014. The in vitto antibacterial activity of thyme oil was assessed by the disc diffusion method and the inhibition zones for the oil at different concentrations, produced against A. baumannii, ranged from 7 to 44 mm. Low level of activity of thyme oil was observed against P. aeruginosa strains. The results of serial dilution tests confirmed the high activity of thyme oil against A. baumannii isolates, expressed as MIC values ranging from 0.25 to 2 μL/mL. These results suggest the need for further studies of antibacterial activity of essential oils, especially against multidrug-resistant bacterial isolates.

  18. Antimicrobial photodynamic therapy in a mouse model of Acinetobacter baumannii burn infection

    Science.gov (United States)

    Dai, Tianhong; Tegos, George P.; Lu, Zongshun; Zhiyentayev, Timur; Huang, Liyi; Franklin, Michael J.; Baer, David G.; Hamblin, Michael R.

    2009-06-01

    Multi-drug resistant Acinetobacter baumanii infections represent a growing problem, especially in traumatic wounds and burns suffered by military personnel injured in Middle Eastern conflicts. Effective treatment using traditional antibiotics can be extremely difficult and new antimicrobial approaches are being investigated. One of these antimicrobial alternatives could be the combination of non-toxic photosensitizers (PS) and visible light known as photodynamic therapy (PDT). We report on the establishment of a new mouse model of full thickness thermal burns infected with a bioluminescent derivative of a clinical Iraqi isolate of A. baumannii and its PDT treatment by topical application of a PS produced by covalent conjugation chlorin(e6) to polyethylenimine followed by illumination of the burn surface with red light. Application of 108 A. baumannii cells to the surface of 10-second burns made on the dorsal surface of shaved female BALB/c mice led to chronic infections that lasted on average 22 days characterized by a remarkably stable bacterial bioluminescence. PDT carried out on day 0 soon after applying bacteria gave over three logs of loss of bacterial luminescence in a light exposure dependent manner, while PDT carried out on day 1 and day 2 gave approximately a 1.7-log reduction. Application of PS dissolved in 10% or 20% DMSO without light gave only modest reduction in bacterial luminescence from mouse burns. Some bacterial regrowth in the treated burn was observed but was generally modest. It was also found that PDT did not lead to inhibition of wound healing. The data suggest that PDT may be an effective new treatment for multi-drug resistant localized A. baumannii infections.

  19. DNA fingerprinting and antimicrobial susceptibility pattern of clinical and environmental Acinetobacter baumannii isolates: a multicentre study.

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    Salimizand, Himen; Menbari, Shaho; Ramazanzadeh, Rashid; Khonsha, Masomeh; Saleh Vahedi, Mohammad

    2016-08-01

    The aims of this study were to establish antibiotic profile and the molecular epidemiology of Acinetobacter baumannii isolates, with considering the effectiveness of control infection measures across three hospitals in the Kurdistan, west part of Iran. Fifty-four A. baumannii isolates were collected from patients and environmental specimens. Antibiotic susceptibility patterns (Antibio-type) were evaluated for 17 different antibiotics and MIC for imipenem was done. Isolates were assessed for the presence of metallo-beta-lactamases (MBLs), class 1 and 2 integrons, and integrated gene cassettes and blaOXA-likefamilies genes. Repetitive-sequence-based PCR (REP-PCR) was done for analysing clonality and relativeness of isolates (REP-type). Antibiotic susceptibility patterns distinguished 11 distinct Antibio-types and REP-PCR showed three clusters with 20 subclusters, mostly belonged to two clonal subgroups, A1 and B1. blaOXA-51 and blaOXA-23 were detected in 100% (54/54) and 52% (28/54), respectively, while blaOXA-24-like and blaOXA-58 were not present in isolates. MBLs were not detected, but, however, high rate of imipenem resistance was observed (52%). MIC90 of imipenem was 16 mg/ml. Class 1 integrons were detected in 11% (6/54) of isolates followed by 24% (13/54) of class 2. Both classes of integron genes were detected in 15% (8/54) of isolates. Integrated gene cassettes were in low level (11% of class 1 harboring isolates). Two arrays of gene cassettes were revealed, dfrA5-like and dfrA17-aadA5. Infection control surveillance should be considered as a serious manner, even the superficial eradication of hospital acquired pathogens. MBL genes were not induced carbapenem resistance in studied hospital settings, but blaOXA-51 & 23 contributed in imipenem resistant. Integrons had a little share in resistance of A. baumannii isolates.

  20. Recurrent bacteremia caused by the Acinetobacter calcoaceticus-Acinetobacter baumannii complex.

    Science.gov (United States)

    Lai, Chih-Cheng; Hsu, Han-Lin; Tan, Che-Kim; Tsai, Hsih-Yeh; Cheng, Aristine; Liu, Chia-Ying; Huang, Yu-Tsung; Liao, Chun-Hsing; Sheng, Wang-Huei; Hsueh, Po-Ren

    2012-09-01

    This study investigated the clinical and microbiological characteristics of patients with recurrent bacteremia caused by the Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex at a medical center. All ACB complex isolates associated with recurrent bacteremia were identified to the genomic species level using a 16S-23S rRNA gene intergenic spacer sequence-based method. Genotypes were determined by the random amplified polymorphic DNA patterns generated by arbitrarily primed PCR and by pulsotypes generated by pulsed-field gel electrophoresis. Relapse of infection was defined as when the genotype of the recurrent isolate was identical to that of the original infecting strain. Reinfection was defined as when the genospecies or genotype of the recurrent isolate differed from that of the original isolate. From 2006 to 2008, 446 patients had ACB complex bacteremia and 25 (5.6%) had recurrent bacteremia caused by the ACB complex. Among the 25 patients, 12 (48%) had relapse of bacteremia caused by A. nosocomialis (n = 7) or A. baumannii (n = 5). Among the 13 patients with reinfection, 5 (38.5%) had reinfection caused by different genospecies of the ACB complex. Most of the patients were immunocompromised, and most of the infection foci were catheter-related bloodstream infections. The overall in-hospital mortality rate was 33.3%. A. baumannii isolates had lower antimicrobial susceptibility rates than A. nosocomialis and A. pittii isolates. In conclusion, relapse of ACB complex bacteremia can develop in immunocompromised patients, especially those with central venous catheters. Molecular methods to identify the ACB complex to the genospecies level are essential for differentiating between reinfection and relapse of bacteremia caused by the ACB complex.

  1. Genetic relatedness and molecular characterization of multidrug resistant Acinetobacter baumannii isolated in central Ohio, USA

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    Tadesse Daniel

    2009-06-01

    Full Text Available Abstract Background Over the last decade, nosocomial infections due to Acinetobacter baumannii have been described with an increasing trend towards multidrug resistance, mostly in intensive care units. The aim of the present study was to determine the clonal relatedness of clinical isolates and to elucidate the genetic basis of imipenem resistance. Methods A. baumannii isolates (n = 83 originated from two hospital settings in central Ohio were used in this study. Pulsed-field gel electrophoresis genotyping and antimicrobial susceptibility testing for clinically relevant antimicrobials were performed. Resistance determinants were characterized by using different phenotypic (accumulation assay for efflux and genotypic (PCR, DNA sequencing, plasmid analysis and electroporation approaches. Results The isolates were predominantly multidrug resistant (>79.5% and comprised of thirteen unique pulsotypes, with genotype VII circulating in both hospitals. The presence of blaOXA-23 in 13% (11/83 and ISAba1 linked blaOXA-66 in 79.5% (66/83 of clinical isolates was associated with high level imipenem resistance. In this set of OXA producing isolates, multidrug resistance was bestowed by blaADC-25, class 1 integron-borne aminoglycoside modifying enzymes, presence of sense mutations in gyrA/parC and involvement of active efflux (with evidence for the presence of adeB efflux gene. Conclusion This study underscores the major role of carbapenem-hydrolyzing class D β-lactamases, and in particular the acquired OXA-23, in the dissemination of imipenem-resistant A. baumannii. The co-occurrence of additional resistance determinant could also be a significant threat.

  2. Variation in the OC locus of Acinetobacter baumannii genomes predicts extensive structural diversity in the lipooligosaccharide.

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    Johanna J Kenyon

    Full Text Available Lipooligosaccharide (LOS is a complex surface structure that is linked to many pathogenic properties of Acinetobacter baumannii. In A. baumannii, the genes responsible for the synthesis of the outer core (OC component of the LOS are located between ilvE and aspS. The content of the OC locus is usually variable within a species, and examination of 6 complete and 227 draft A. baumannii genome sequences available in GenBank non-redundant and Whole Genome Shotgun databases revealed nine distinct new types, OCL4-OCL12, in addition to the three known ones. The twelve gene clusters fell into two distinct groups, designated Group A and Group B, based on similarities in the genes present. OCL6 (Group B was unique in that it included genes for the synthesis of L-Rhamnosep. Genetic exchange of the different configurations between strains has occurred as some OC forms were found in several different sequence types (STs. OCL1 (Group A was the most widely distributed being present in 18 STs, and OCL6 was found in 16 STs. Variation within clones was also observed, with more than one OC locus type found in the two globally disseminated clones, GC1 and GC2, that include the majority of multiply antibiotic resistant isolates. OCL1 was the most abundant gene cluster in both GC1 and GC2 genomes but GC1 isolates also carried OCL2, OCL3 or OCL5, and OCL3 was also present in GC2. As replacement of the OC locus in the major global clones indicates the presence of sub-lineages, a PCR typing scheme was developed to rapidly distinguish Group A and Group B types, and to distinguish the specific forms found in GC1 and GC2 isolates.

  3. Acinetobacter baumannii isolates from pets and horses in Switzerland: molecular characterization and clinical data

    Science.gov (United States)

    Endimiani, Andrea; Hujer, Kristine M.; Hujer, Andrea M.; Bertschy, Isabelle; Rossano, Alexandra; Koch, Christoph; Gerber, Vinzenz; Francey, Thierry; Bonomo, Robert A.; Perreten, Vincent

    2011-01-01

    Objectives We investigated whether Acinetobacter baumannii isolates of veterinary origin shared common molecular characteristics with those described in humans. Methods Nineteen A. baumannii isolates collected in pets and horses were analysed. Clonality was studied using repetitive extragenic palindromic PCR (rep-PCR) and multilocus sequence typing (MLST). PCR and DNA sequencing for various β-lactamase, aminoglycoside-modifying enzyme, gyrA and parC, ISAba1 and IS1133, adeR and adeS of the AdeABC efflux pump, carO porin and class 1/2/3 integron genes were performed. Results Two main clones [A (n = 8) and B (n = 9)] were observed by rep-PCR. MLST indicated that clone A contained isolates of sequence type (ST) ST12 (international clone II) and clone B contained isolates of ST15 (international clone I). Two isolates of ST10 and ST20 were also noted. Seventeen isolates were resistant to gentamicin, 12 to ciprofloxacin and 3 to carbapenems. Isolates of ST12 carried blaOXA-66, blaADC-25, blaTEM-1, aacC2 and IS1133. Strains of ST15 possessed blaOXA-69, blaADC-11, blaTEM-1 and a class 1 integron carrying aacC1 and aadA1. ISAba1 was found upstream of blaADC (one ST10 and one ST12) and/or blaOXA-66 (seven ST12). Twelve isolates of different STs contained the substitutions Ser83Leu in GyrA and Ser80Leu or Glu84Lys in ParC. Significant disruptions of CarO porin and overexpressed efflux pumps were not observed. The majority of infections were hospital acquired and in animals with predisposing conditions for infection. Conclusions STs and the molecular background of resistance observed in our collection have been frequently described in A. baumannii detected in human patients. Animals should be considered as a potential reservoir of multidrug-resistant A. baumannii. PMID:21733964

  4. Structure of diaminohydroxyphosphoribosylaminopyrimidine deaminase/5-amino-6-(5-phosphoribosylamino)uracil reductase from Acinetobacter baumannii.

    Science.gov (United States)

    Dawson, Alice; Trumper, Paul; Chrysostomou, Georgios; Hunter, William N

    2013-06-01

    The bifunctional diaminohydroxyphosphoribosylaminopyrimidine deaminase/5-amino-6-(5-phosphoribosylamino)uracil reductase (RibD) represents a potential antibacterial drug target. The structure of recombinant Acinetobacter baumannii RibD is reported in orthorhombic and tetragonal crystal forms at 2.2 and 2.0 Å resolution, respectively. Comparisons with orthologous structures in the Protein Data Bank indicated close similarities. The tetragonal crystal form was obtained in the presence of guanosine monophosphate, which surprisingly was observed to occupy the adenine-binding site of the reductase domain.

  5. Light Modulates Metabolic Pathways and Other Novel Physiological Traits in the Human Pathogen Acinetobacter baumannii.

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    Müller, Gabriela L; Tuttobene, Marisel; Altilio, Matías; Martínez Amezaga, Maitena; Nguyen, Meaghan; Cribb, Pamela; Cybulski, Larisa E; Ramírez, María Soledad; Altabe, Silvia; Mussi, María Alejandra

    2017-05-15

    Light sensing in chemotrophic bacteria has been relatively recently ascertained. In the human pathogen Acinetobacter baumannii , light modulates motility, biofilm formation, and virulence through the blue-light-sensing-using flavin (BLUF) photoreceptor BlsA. In addition, light can induce a reduction in susceptibility to certain antibiotics, such as minocycline and tigecycline, in a photoreceptor-independent manner. In this work, we identified new traits whose expression levels are modulated by light in this pathogen, which comprise not only important determinants related to pathogenicity and antibiotic resistance but also metabolic pathways, which represents a novel concept for chemotrophic bacteria. Indeed, the phenylacetic acid catabolic pathway and trehalose biosynthesis were modulated by light, responses that completely depend on BlsA. We further show that tolerance to some antibiotics and modulation of antioxidant enzyme levels are also influenced by light, likely contributing to bacterial persistence in adverse environments. Also, we present evidence indicating that surfactant production is modulated by light. Finally, the expression of whole pathways and gene clusters, such as genes involved in lipid metabolism and genes encoding components of the type VI secretion system, as well as efflux pumps related to antibiotic resistance, was differentially induced by light. Overall, our results indicate that light modulates global features of the A. baumannii lifestyle. IMPORTANCE The discovery that nonphototrophic bacteria respond to light constituted a novel concept in microbiology. In this context, we demonstrated that light could modulate aspects related to bacterial virulence, persistence, and resistance to antibiotics in the human pathogen Acinetobacter baumannii In this work, we present the novel finding that light directly regulates metabolism in this chemotrophic bacterium. Insights into the mechanism show the involvement of the photoreceptor BlsA. In

  6. Surveillance of multidrug resistance-associated genes in Acinetobacter baumannii isolates from elderly patients

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    Zhe DONG

    2012-03-01

    Full Text Available Objective To understand the status of multidrug resistance-associated genes carried by Acinetobacter baumannii isolates from elderly patients in our hospital in order to provide a basis for surveillance of drug-resistance and inflection control. Methods One hundred and twenty A. baumannii isolates were collected from elderly patients between 2008 and 2010. The mean age of the patients was 85 (65 to 95 years. Whonet 5.6 software was used to analyze the resistance rate of 16 antimicrobial agents. Polymerase chain reaction (PCR and the sequencing method were adopted to detect 10 kinds of resistance genes (blaOXA-51-like, blaOXA- 23-like, blaOXA-24-like, blaOXA-58-like, blaTEM, blaampC, armA, ISAba1, intI 1, and intI 2. The corresponding resistance gene profiling(RGP was analyzed and designated according to the status of resistance genes. Results The resistance rates to the remaining 15 kinds of antibiotics varied between 70.8% and 97.5%, with the exception of the sensitivity rate to polymyxin B by up to more than 90%. The positivity rates of blaOXA-51-like, blaOXA-23-like, blaOXA-58-like, blaTEM, blaampC, armA, ISAba1 and intI 1 were 100%, 81.7%, 0.8%, 10.8%, 91.7%, 81.7%, 86.7%, and 83.3% respectively. A total of 18 kinds of drug-resistant gene maps were found, but blaOXA-24-like and intI 2 were not detected. Among these gene maps, the rate of RGP1 (blaOXA-23-like+blaampC+armA+ISAba1+ intI 1 was as high as 60.8%. Conclusions A. baumannii isolates from elderly patients have a higher carrying rate of drug-resistant genes, resulting in severe multidrugresistant conditions. Therefore, full-time infection control personnel and clinical physicians should actively participate in the surveillance, prevention, and control of infections caused by A. baumannii in the elderly.

  7. In vitro synergistic activity of colistin with tigecycline or β-lactam antibiotic/β-lactamase inhibitor combinations against carbapenem-resistant Acinetobacter baumannii.

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    Karaoglan, Ilkay; Zer, Yasemin; Bosnak, Vuslat Kecik; Mete, Ayse Ozlem; Namiduru, Mustafa

    2013-12-01

    Nosocomial infection caused by carbapenem-resistant Acinetobacter baumannii is a worldwide problem and treatment options remain controversial. This study investigated the in vitro effect of various antibiotic combinations against carbapenem-resistant A. baumannii strains. Antibiotic susceptibility of A. baumannii strains was analysed. In vitro synergistic efficacy of colistin combined with tigecycline, cefoperazone/sulbactam or piperacillin/tazobactam was tested against carbapenem-resistant A. baumannii strains. Synergy studies were performed using an eplisometer test-strip method. Of the 50 carbapenem-resistant A. baumannii strains tested, 96% were susceptible to colistin and 64% were susceptible to tigecycline. Colistin-tigecycline, colistin-cefoperazone/sulbactam and colistin-piperacillin/tazobactam combinations were found to have synergistic effects against six (12%), two (4%), and one (2%), respectively, of the strains tested. Colistin combined with tigecycline, cefoperazone/sulbactam or piperacillin/tazobactam revealed synergistic effects in some carbapenem-resistant A. baumannii strains. These results, together with the shortage of treatment options and the risk of developing resistance to colistin, suggest that clinicians should use colistin combined with other antibiotics or β-lactamase inhibitors when treating carbapenem-resistant A. baumannii infection.

  8. The Tail Associated Protein of Acinetobacter baumannii Phage ΦAB6 Is the Host Specificity Determinant Possessing Exopolysaccharide Depolymerase Activity.

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    Meng-Jiun Lai

    Full Text Available Acinetobacter baumannii is a non-fermenting, gram-negative bacterium. In recent years, the frequency of A. baumannii infections has continued to increase, and multidrug-resistant strains are emerging in hospitalized patients. Therefore, as therapeutic options become limited, the potential of phages as natural antimicrobial agents to control infections is worth reconsidering. In our previous study, we isolated ten virulent double-stranded DNA A. baumannii phages, ϕAB1-9 and ϕAB11, and found that each has a narrow host range. Many reports indicate that receptor-binding protein of phage mediates host recognition; however, understanding of the specific interactions between A. baumannii and phages remains very limited. In this study, host determinants of A. baumannii phages were investigated. Sequence comparison of ϕAB6 and ϕAB1 revealed high degrees of conservation among their genes except the tail fiber protein (ORF41 in ϕAB1 and ORF40 in ϕAB6. Furthermore, we found that ORF40ϕAB6 has polysaccharide depolymerase activity capable of hydrolyzing the A. baumannii exopolysaccharide and is a component of the phage tail apparatus determining host specificity. Thus, the lytic phages and their associated depolymerase not only have potential as alternative therapeutic agents for treating A. baumannii infections but also provide useful and highly specific tools for studying host strain exopolysaccharides and producing glycoconjugate vaccines.

  9. Oligonucleotide array-based identification of species in the Acinetobacter calcoaceticus-A. baumannii complex in isolates from blood cultures and antimicrobial susceptibility testing of the isolates.

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    Ko, Wen-Chien; Lee, Nan-Yao; Su, Siou Cing; Dijkshoorn, Lenie; Vaneechoutte, Mario; Wang, Li-Rong; Yan, Jin-Jou; Chang, Tsung Chain

    2008-06-01

    Acinetobacter calcoaceticus, A. baumannii, Acinetobacter genomic species (gen. sp.) 3, and Acinetobacter gen. sp. 13TU, which are included in the A. calcoaceticus-A. baumannii complex, are difficult to distinguish by phenotypic methods. An array with six oligonucleotide probes based on the 16S-23S rRNA gene intergenic spacer (ITS) region was developed to differentiate species in the A. calcoaceticus-A. baumannii complex. Validation of the array with a reference collection of 52 strains of the A. calcoaceticus-A. baumannii complex and 137 strains of other species resulted in an identification sensitivity and specificity of 100%. By using the array, the species distribution of 291 isolates of the A. calcoaceticus-A. baumannii complex from patients with bacteremia were determined to be A. baumannii (221 strains [75.9%]), Acinetobacter gen. sp. 3 (67 strains [23.0%]), Acinetobacter gen. sp. 13TU (2 strains [0.7%]), and unidentified Acinetobacter sp. (1 strain [0.3%]). The identification accuracy of the array for 12 randomly selected isolates from patients with bacteremia was further confirmed by sequence analyses of the ITS region and the 16S rRNA gene. Antimicrobial susceptibility testing of the 291 isolates from patients with bacteremia revealed that A. baumannii strains were less susceptible to antimicrobial agents than Acinetobacter gen. sp. 3. All Acinetobacter gen. sp. 3 strains were susceptible to ampicillin-sulbactam, imipenem, and meropenem; but only 67.4%, 90%, and 86% of the A. baumannii strains were susceptible to ampicillin-sulbactam, imipenem, and meropenem, respectively. The observed significant variations in antimicrobial susceptibility among different species in the A. calcoaceticus-A. baumannii complex emphasize that the differentiation of species within the complex is relevant from a clinical-epidemiological point of view.

  10. Changes in antimicrobial susceptibility and major clones of Acinetobacter calcoaceticus-baumannii complex isolates from a single hospital in Korea over 7 years.

    Science.gov (United States)

    Park, Young Kyoung; Jung, Sook-In; Park, Kyong-Hwa; Kim, Dae Hun; Choi, Ji Young; Kim, Su Hwan; Ko, Kwan Soo

    2012-01-01

    Acinetobacter species have emerged as opportunistic nosocomial pathogens in intensive care units. Epidemic spread and outbreaks of multidrug-resistant or carbapenem-resistant Acinetobacter baumannii infections have been described worldwide. Species distribution, antimicrobial resistance and genotypes were investigated for Acinetobacter species isolates collected from a single institution in Korea over 7 years. Two hundred and eighty-seven Acinetobacter species isolates were collected from patients with bloodstream infections in one Korean hospital from 2003 to 2010. Most of them belonged to the Acinetobacter calcoaceticus-baumannii complex (94.4 %). The most frequently isolated species was A. baumannii (44.2 %), followed by Acinetobacter nosocomialis (formerly Acinetobacter genomic species 13TU) (34.1 %). The proportion of A. baumannii increased significantly from 2008 to 2010 (40.4 to 50.0 %). From 2008, imipenem and meropenem resistance rates increased significantly compared with 2003-2007 (12.9 % and 20.5 %, respectively, to 41.4 % and 41.5 %, respectively). An increased carbapenem resistance rate between the two periods was identified more clearly amongst A. baumannii isolates. Polymyxin-resistant A. baumannii isolates emerged in 2008-2010, despite the availability of few isolates. The increase of carbapenem resistance in A. baumannii might be due to the substitution of main clones. Although ST92 and ST69 were the most prevalent clones amongst A. baumannii in 2003-2007 (47.8 % and 15.9 %, respectively), ST75 and ST138 had increased in 2008-2010 (39.7 % and 25.9 %, respectively). Although ST92 showed moderate resistance to carbapenems, most ST75 and ST138 isolates were resistant to carbapenems. All ST75 and ST138 isolates, but only one ST92 isolate, contained the bla(OXA-23-like) gene. Increased carbapenem resistance in Acinetobacter species and A. baumannii isolates might be due to the expansion of specific carbapenem-resistant clones.

  11. An amphipathic undecapeptide with all D-amino acids shows promising activity against colistin-resistant strains of Acinetobacter baumannii and a dual mode of action

    DEFF Research Database (Denmark)

    Oddo, Alberto; Thomsen, Thomas Thyge; Kjelstrup, Susanne

    2016-01-01

    Multiple strains of Acinetobacter baumannii have developed multidrug resistance (MDR), leaving colistin as the only effective treatment. The cecropin-α-melittin hybrid BP100 (KKLFKKILKYL-NH2) and its analogs have previously shown activity against a wide array of plant and human pathogens....... In this study, we investigated the in vitro antibacterial activities of 18 BP100 analogs (four known and 14 new) against the MDR A. baumannii strain ATCC BAA-1605, as well as against a number of other clinically relevant human pathogens. Selected peptides were further evaluated against strains of A. baumannii...

  12. RAGE-Mediated Suppression of Interleukin-10 Results in Enhanced Mortality in a Murine Model of Acinetobacter baumannii Sepsis.

    Science.gov (United States)

    Noto, Michael J; Becker, Kyle W; Boyd, Kelli L; Schmidt, Ann Marie; Skaar, Eric P

    2017-03-01

    The receptor for advanced glycation end products (RAGE) is a pattern recognition receptor capable of recognizing multiple pathogen-associated and danger-associated molecular patterns that contributes to the initiation and potentiation of inflammation in many disease processes. During infection, RAGE functions to either exacerbate disease severity or enhance pathogen clearance depending on the pathogen studied. Acinetobacter baumannii is an opportunistic human pathogen capable of causing severe infections, including pneumonia and sepsis, in impaired hosts. The role of RAGE signaling in response to opportunistic bacterial infections is largely unknown. In murine models of A. baumannii pneumonia, RAGE signaling alters neither inflammation nor bacterial clearance. In contrast, RAGE -/- mice systemically infected with A. baumannii exhibit increased survival and reduced bacterial burdens in the liver and spleen. The increased survival of RAGE -/- mice is associated with increased circulating levels of the anti-inflammatory cytokine interleukin-10 (IL-10). Neutralization of IL-10 in RAGE -/- mice results in decreased survival during systemic A. baumannii infection that mirrors that of wild-type (WT) mice, and exogenous IL-10 administration to WT mice enhances survival in this model. These findings demonstrate the role for RAGE-dependent IL-10 suppression as a key modulator of mortality from Gram-negative sepsis. Copyright © 2017 American Society for Microbiology.

  13. Amide side chain amphiphilic polymers disrupt surface established bacterial bio-films and protect mice from chronic Acinetobacter baumannii infection.

    Science.gov (United States)

    Uppu, Divakara S S M; Samaddar, Sandip; Ghosh, Chandradhish; Paramanandham, Krishnamoorthy; Shome, Bibek R; Haldar, Jayanta

    2016-01-01

    Bacterial biofilms represent the root-cause of chronic or persistent infections in humans. Gram-negative bacterial infections due to nosocomial and opportunistic pathogens such as Acinetobacter baumannii are more difficult to treat because of their inherent and rapidly acquiring resistance to antibiotics. Due to biofilm formation, A. baumannii has been noted for its apparent ability to survive on artificial surfaces for an extended period of time, therefore allowing it to persist in the hospital environment. Here we report, maleic anhydride based novel cationic polymers appended with amide side chains that disrupt surface established multi-drug resistant A. baumannii biofilms. More importantly, these polymers significantly (p polymers also show potent antibacterial efficacy against methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococci (VRE) and multi-drug resistant clinical isolates of A. baumannii with minimal toxicity to mammalian cells. We observe that optimal hydrophobicity dependent on the side chain chemical structure of these polymers dictate the selective toxicity to bacteria. Polymers interact with the bacterial cell membranes by causing membrane depolarization, permeabilization and energy depletion. Bacteria develop rapid resistance to erythromycin and colistin whereas no detectable development of resistance occurs against these polymers even after several passages. These results suggest the potential use of these polymeric biomaterials in disinfecting biomedical device surfaces after the infection has become established and also for the topical treatment of chronic bacterial infections. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Rapid dissemination of colistin and carbapenem resistant Acinetobacter baumannii in Central Greece: mechanisms of resistance, molecular identification and epidemiological data.

    Science.gov (United States)

    Oikonomou, O; Sarrou, S; Papagiannitsis, C C; Georgiadou, S; Mantzarlis, K; Zakynthinos, E; Dalekos, G N; Petinaki, E

    2015-12-09

    Colistin-resistant/carbapenem-resistant Acinetobacter baumannii is a significant challenge for antibiotic treatment and infection control policies. Since 2012, in Central Greece an increase of colistin/pan- resistant A. baumannii has occurred, indicating the need for further analysis. A total of 86 colistin-resistant/carbapenem-resistant out of 1228 A. baumannii clinical isolates, consecutively collected between 2012 and 2014 in a tertiary Greek hospital of Central Greece, as well as one environmental isolate from surveillance cultures were studied. Molecular typing and mechanisms of resistance to colistin and to carbapenems were assessed, whereas, epidemiological and clinical data of the patients were reviewed. During the study period, the rate of colistin resistance gradually increased and reached 21.1 % in 2014. All colistin-resistant/carbapenem-resistant A. baumannii belonged to 3LST ST101 clone that corresponds to the international clonal lineage II. Carbapenem resistance was associated with the presence of bla oxa-23-like, while resistance to colistin probably correlated with G54E and R109H amino acid substitutions in PmrA and PmrC, respectively. Epidemiological data of the patients indicated that the first detection of colistin-resistant/carbapenem-resistant ST101 clone in the University Hospital of Larissa (UHL) was associated with a patient who previously had received colistin, while, the movement of the infected patients into the hospital probably resulted to its spread.

  15. Functional Characterization of AbeD, an RND-Type Membrane Transporter in Antimicrobial Resistance in Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Vijaya Bharathi Srinivasan

    Full Text Available Acinetobacter baumannii is becoming an increasing menace in health care settings especially in the intensive care units due to its ability to withstand adverse environmental conditions and exhibit innate resistance to different classes of antibiotics. Here we describe the biological contributions of abeD, a novel membrane transporter in bacterial stress response and antimicrobial resistance in A. baumannii.The abeD mutant displayed ~ 3.37 fold decreased survival and >5-fold reduced growth in hostile osmotic (0.25 M; NaCl and oxidative (2.631 μM-6.574 μM; H2O2 stress conditions respectively. The abeD inactivated cells displayed increased susceptibility to ceftriaxone, gentamicin, rifampicin and tobramycin (~ 4.0 fold. The mutant displayed increased sensitivity to the hospital-based disinfectant benzalkonium chloride (~3.18-fold. In Caenorhabditis elegans model, the abeD mutant exhibited (P<0.01 lower virulence capability. Binding of SoxR on the regulatory fragments of abeD provide strong evidence for the involvement of SoxR system in regulating the expression of abeD in A. baumannii.This study demonstrates the contributions of membrane transporter AbeD in bacterial physiology, stress response and antimicrobial resistance in A. baumannii for the first time.

  16. Enhanced antibacterial activity of Acinetobacter baumannii bacteriophage ØABP-01 endolysin (LysABP-01 in combination with colistin

    Directory of Open Access Journals (Sweden)

    Rapee Thummeepak

    2016-09-01

    Full Text Available Endolysins are lytic enzymes produced by bacteriophages with their ability to degrade the cell wall of bacterial hosts. Endolysin (LysABP-01 from A. baumannii bacteriophage ØABP-01 was cloned, overexpressed and characterized. Endolysin LysABP-01 has a modular structure consisting of lysozyme-like (N-acetyl-β-d-muramidase catalytic domain. It contains 185 amino acids which correspond to a 21.1 kDa protein. The lytic activity of the recombinant endolysin protein was determined by a plate lysis assay for its ability to lyse the autoclaved cell (crude cell wall of the different bacterial species. LysABP-01 can degrade the crude cell wall of A. baumannii strains, Escherichia coli and Pseudomonas aeruginosa but not of Staphylococcus aureus. The antibacterial activity of LysABP-01 and its synergism with various antibiotics were tested. The results exhibited elevated antibacterial activity in a combination of the sub-MIC LysABP-01 and colistin. The checkerboard assay for measuring antibiotic synergy of LysABP-01 and colistin was performed. This combination was synergistic against various drug-resistant strains of A. baumannii (FIC index < 0.5. In summary, our study highlights the ability of LysABP-01 endolysin to hydrolyze the A. baumannii cell wall and its synergistic interaction with colistin.

  17. Enhanced Antibacterial Activity of Acinetobacter baumannii Bacteriophage ØABP-01 Endolysin (LysABP-01) in Combination with Colistin.

    Science.gov (United States)

    Thummeepak, Rapee; Kitti, Thawatchai; Kunthalert, Duangkamol; Sitthisak, Sutthirat

    2016-01-01

    Endolysins are lytic enzymes produced by bacteriophages with their ability to degrade the cell wall of bacterial hosts. Endolysin (LysABP-01) from Acinetobacter baumannii bacteriophage ØABP-01 was cloned, overexpressed and characterized. Endolysin LysABP-01 has a globular structure consisting of lysozyme-like (N-acetyl-β-D-muramidase) catalytic domain. It contains 185 amino acids which correspond to a 21.1 kDa protein. The lytic activity of the recombinant endolysin protein was determined by a plate lysis assay for its ability to lyse the autoclaved cell (crude cell wall) of the different bacterial species. LysABP-01 can degrade the crude cell wall of A. baumannii strains, Escherichia coli and Pseudomonas aeruginosa but not of Staphylococcus aureus. The antibacterial activity of LysABP-01 and its synergism with various antibiotics were tested. The results exhibited elevated antibacterial activity in a combination of the sub-MIC LysABP-01 and colistin. The checkerboard assay for measuring antibiotic synergy of LysABP-01 and colistin was performed. This combination was synergistic against various drug-resistant strains of A. baumannii (FIC index endolysin to hydrolyze the A. baumannii cell wall and its synergistic interaction with colistin.

  18. Spread of carbapenem-resistant international clones of Acinetobacter baumannii in Turkey and Azerbaijan: a collaborative study

    NARCIS (Netherlands)

    Ahmed, S.S.; Alp, E.; Ulu-Kilic, A.; Dinc, G.; Aktas, Z.; Ada, B.; Bagirova, F.; Baran, I.; Ersoy, Y.; Esen, S.; Guven, T.G.; Hopman, J.; Hosoglu, S.; Koksal, F.; Parlak, E.; Yalcin, A.N.; Yilmaz, G.; Voss, A.; Melchers, W.J.

    2016-01-01

    Epidemic clones of Acinetobacter baumannii, described as European clones I, II, and III, are associated with hospital epidemics throughout the world. We aimed to determine the molecular characteristics and genetic diversity between European clones I, II, and III from Turkey and Azerbaijan. In this

  19. Characterization of surface antigen protein 1 (SurA1) from Acinetobacter baumannii and its role in virulence and fitness.

    Science.gov (United States)

    Liu, Dong; Liu, Zeng-Shan; Hu, Pan; Cai, Ling; Fu, Bao-Quan; Li, Yan-Song; Lu, Shi-Ying; Liu, Nan-Nan; Ma, Xiao-Long; Chi, Dan; Chang, Jiang; Shui, Yi-Ming; Li, Zhao-Hui; Ahmad, Waqas; Zhou, Yu; Ren, Hong-Lin

    2016-04-15

    Acinetobacter baumannii is a Gram-negative bacillus that causes nosocomial infections, such as bacteremia, pneumonia, and meningitis and urinary tract and wound infections. In the present study, the surface antigen protein 1 (SurA1) gene of A. baumannii strain CCGGD201101 was identified, cloned and expressed, and then its roles in fitness and virulence were investigated. Virulence was observed in the human lung cancer cell lines A549 and HEp-2 at one week after treatment with recombinant SurA1. One isogenic SurA1 knock-out strain, GR0015, which was derived from the A. baumannii strain CCGGD201101 isolated from diseased chicks in a previous study, highlighted the effect of SurA1 on fitness and growth. Its growth rate in LB broth and killing activity in human sera were significantly decreased compared with strain CCGGD201101. In the Galleria mellonella insect model, the isogenic SurA1 knock-out strain exhibited a lower survival rate and decreased dissemination. These results suggest that SurA1 plays an important role in the fitness and virulence of A. baumannii. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Molecular characteristics of Multidrug Resistant Acinetobacter baumannii Isolates from US soldiers from Iraq at the National Naval Medical Center

    Science.gov (United States)

    Background: Infections with A. baumannii-calcoaceticus complex (ABC) have complicated the care of combat casualties, and the spread and global dissemination of imipenem resistant (IR) clones of ABC have been reported in recent years. However, the epidemiological features of the IR-ABCs in military t...

  1. Correlation between ability of biofilm formation with their responsible genes and MDR patterns in clinical and environmental Acinetobacter baumannii isolates.

    Science.gov (United States)

    Bardbari, Ali Mohammadi; Arabestani, Mohammad Reza; Karami, Manoochehr; Keramat, Fariba; Alikhani, Mohammad Yousef; Bagheri, Kamran Pooshang

    2017-07-01

    Acinetobacter baumannii potential to form biofilm and exhibit multiple antibiotic resistances may be responsible in its survival in hospital environment. Accordingly, our study was aimed to determine the correlation between ability of biofilm formation and the frequency of biofilm related genes with antibiotic resistance phenotypes, and also the categorization of their patterns in clinical and environmental isolates. A total of 75 clinical and 32 environmental strains of the A. baumannii were collected and identified via API 20NE. Antibiotic susceptibility was evaluated by disk diffusion and microdilution broth methods. Biofilm formation assay was performed by microtiter plate method. OXA types and biofilm related genes including Bla OXA-51 , Bla OXA-23 , Bla OXA-24 , Bla OXA-58 , bap, bla PER-1 , and ompA were amplified by PCR. The rate of MDR A. baumannii in clinical isolates (100%) was higher than environmental (81.2%) isolates (p baumannii isolates was associated with biofilm formation. There was a significant correlation between multiple drug resistance and biofilm formation. The clinical isolates had a higher ability to form strong biofilms compared to the environmental samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Molecular analysis of imipenem-resistant Acinetobacter baumannii isolated from US service members wounded in Iraq, 2003–2008

    Science.gov (United States)

    Clonal spread and global dissemination of imipenem resistant (IR) A. baumannii-A. calcoaceticus complex (ABC) have been reported in recent years. However, the epidemiological features of the IR-ABCs in military treatment facilities (MTFs) have not been systematically studied. In this study, 298 ABC...

  3. OXA-carbapenemases present in clinical acinetobacter baumannii-calcoaceticus complex isolates from patients in kurdistan region, Iraq

    NARCIS (Netherlands)

    Ganjo, A.R. (Aryann R.); D.M. Maghdid (Delshad); Mansoor, I.Y. (Isam Y.); Kok, D.J. (Dik J.); J.A. Severin (Juliëtte); H.A. Verbrugh (Henri); D. Kreft; Fatah, M.H.; Alnakshabandi, A.A.; Dlnya, A. (Asad); Hammerum, A.M. (Anette M.); Ng, K. (Kim); W.H.F. Goessens (Wil)

    2016-01-01

    markdownabstractIn addition to intrinsic resistance in Acinetobacter baumannii, many different types of acquired resistance mechanisms have been reported, including the presence of VIM and IMP metallo β-lactamases and also of blaOXA-23-like and blaOXA-58-like enzymes. In the Kurdistan region of

  4. The acute-phase response and serum amyloid A inhibit the inflammatory response to Acinetobacter baumannii Pneumonia

    NARCIS (Netherlands)

    Renckens, Rosemarijn; Roelofs, Joris J. T. H.; Knapp, Sylvia; de Vos, Alex F.; Florquin, Sandrine; van der Poll, Tom

    2006-01-01

    BACKGROUND: Acinetobacter baumannii is an emerging pathogen in nosocomial pneumonia. Trauma and postsurgical patients display a profound acute-phase protein response and are susceptible to pneumonia. METHODS: To study the way in which the acute-phase response induced by sterile tissue injury

  5. Multi-drug-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex infection outbreak in dogs and cats in a veterinary hospital.

    Science.gov (United States)

    Kuzi, S; Blum, S E; Kahane, N; Adler, A; Hussein, O; Segev, G; Aroch, I

    2016-11-01

    Members of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex cause severe outbreaks in humans, and are increasingly reported in animals. A retrospective study, describing a severe outbreak in dogs and cats caused by a multidrug resistant member of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in a veterinary hospital, between July 2010 and November 2012. The study included 19 dogs and 4 cats. Acinetobacter calcoaceticus-Acinetobacter baumannii complex bacteria were isolated from urine (9 animals), respiratory tract (11), tissues (3) and blood (1). The most common infection-associated findings included fever, purulent discharge from endotracheal tubes, hypotension, and neutropaenia. Infections led to pneumonia, urinary tract infection, cellulitis and sepsis. Infection was transmitted in the intensive care unit, where 22 of 23 animals were initially hospitalised. The mortality rate was 70% (16 of 23 animals), and was higher in cases of respiratory infection compared to other infections. Aggressive environmental cleaning and disinfection, with staff education for personal hygiene and antisepsis, sharply decreased the infection incidence. Health care-associated outbreaks with multidrug resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex in dogs and cats are potentially highly fatal and difficult to eradicate, warranting monitoring, antiseptic techniques and judicious antibiotic use. © 2016 British Small Animal Veterinary Association.

  6. A data-driven mathematical model of multi-drug resistant Acinetobacter baumannii transmission in an intensive care unit

    NARCIS (Netherlands)

    Wang, Xia; Chen, Yong; Zhao, Wei; Wang, Yan; Song, Qing; Liu, Hui; Zhao, Jingya; Han, Xuelin; Hu, Xiaohua; Grundmann, Hajo; Xiao, Yanni; Han, Li

    2015-01-01

    Major challenges remain when attempting to quantify and evaluate the impacts of contaminated environments and heterogeneity in the cohorting of health care workers (HCWs) on hospital infections. Data on the detection rate of multidrug-resistant Acinetobacter baumannii (MRAB) in a Chinese intensive

  7. Structure of the neutral capsular polysaccharide of Acinetobacter baumannii NIPH146 that carries the KL37 capsule gene cluster.

    Science.gov (United States)

    Arbatsky, Nikolay P; Shneider, Mikhail M; Kenyon, Johanna J; Shashkov, Alexander S; Popova, Anastasiya V; Miroshnikov, Konstantin A; Volozhantsev, Nikolay V; Knirel, Yuriy A

    2015-09-02

    Capsular polysaccharide (CPS) was isolated from Acinetobacter baumannii NIPH146, and the following structure of branched pentasaccharide repeating unit was established by sugar analyses along with 1D and 2D NMR spectroscopy: In comparison to most other known capsular polysaccharides of A. baumannii, the CPS studied is neutral and lacks any specific monosaccharide component. The synthesis, assembly and export of this structure could be attributed to genes in a novel capsule biosynthesis gene cluster, designated KL37, which was found in the NIPH146 genome. The CPS of A. baumannii NIPH146 shares the α-d-Galp-(1→6)-β-d-Glcp-(1→3)-d-GalpNAc-(1→ trisaccharide fragment with the CPS units of several A. baumannii strains, including ATCC 17978 and LUH 5537 that carry the KL3 and KL22 gene clusters, respectively. KL37 contains two genes for glycosyltransferases that are related to two glycosyltransferase genes present in both KL3 and KL22, and the encoded proteins could be tentatively assigned to linkages between sugars in the CPS repeat. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Flow boiling in expanding microchannels

    CERN Document Server

    Alam, Tamanna

    2017-01-01

    This Brief presents an up to date summary of details of the flow boiling heat transfer, pressure drop and instability characteristics; two phase flow patterns of expanding microchannels. Results obtained from the different expanding microscale geometries are presented for comparison and addition to that, comparison with literatures is also performed. Finally, parametric studies are performed and presented in the brief. The findings from this study could help in understanding the complex microscale flow boiling behavior and aid in the design and implementation of reliable compact heat sinks for practical applications.

  9. The antibacterial activity of some essential oils against clinical isolates of Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Mohaddese Mahboubi

    2014-10-01

    Full Text Available Acinetobacter baumannii is categorized as a red alert pathogen that is increasingly associated with a high mortality rate in infected patients due to its resistance to extensive antibiotics. In this study, we evaluated the antibacterial activities of some essential oils (Oliveria decumbens, Pelargonium graveolens, Eugenia caryophyllata, Ziziphora tenuir and Trachyspermum copticum oils against 32 clinical isolates of A. baumannii. The antibacterial evaluations and chemical composition of essential oils was determined. Thymol, eugenol, -terpineol, -citronellol and thymol were the chief portions of T. copticum, E. caryophyllata, Z. tenuir, O. decumbens and P. graveolens oils, respectively. The MIC values of oils against these clinical isolates revealed the three subsets of oils including 1- T. copticum, E. caryophyllata and O. decumbens, 2- Z. tenuir and 3- P. graveolens oils. These oils showed the synergistic activity with amikacin, the lower Fractional Inhibitory Concentration Index (FICI was for P. graveolens oil (0.23 and the higher FICI was for E. caryophyllata (0.325.

  10. A health care-associated pneumonia case due to colistin resistant Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Siran Keske

    2014-09-01

    Full Text Available A 78 year old male was hospitalized in neurology clinic with a diagnosis of encephalopathy. On 13th day of imipenem treatment for ventilator-associated pneumonia (VAP, a new VAP episode was diagnosed based on physical examination, laboratory and radiological findings. Cefoperazone-sulbactam 2x2 gr/day IV was started empirically. In the 3rd day of treatment Acinetobacter baumannii was identified from endotracheal aspirate culture that was resistant to all other antibiotics including colistin except cefoperazone-sulbactam (intermediate and tigecycline (MIC: 4 mg/L, intermediate by VITEK and E-test. Tigecycline 2 x 50 mg (after loading dose of 100 mg IV, colistin IV 2 x 150 mg and colistin inhaler 2 x 75 mg were added to the cefoperazone-sulbactam 2 x 2 gr IV. Clinical findings were improved under this combination and completed to 14 days. The patient was discharged from hospital with neurological sequel after three months. This case has been presented to emphasize that colistin resistant Acinetobacter baumannii is becoming a problem for our country. J Microbiol Infect Dis 2014; 4(3: 111-113

  11. Crystal Structure of Hcp from Acinetobacter baumannii: A Component of the Type VI Secretion System.

    Directory of Open Access Journals (Sweden)

    Federico M Ruiz

    Full Text Available The type VI secretion system (T6SS is a bacterial macromolecular machine widely distributed in Gram-negative bacteria, which transports effector proteins into eukaryotic host cells or other bacteria. Membrane complexes and a central tubular structure, which resembles the tail of contractile bacteriophages, compose the T6SS. One of the proteins forming this tube is the hemolysin co-regulated protein (Hcp, which acts as virulence factor, as transporter of effectors and as a chaperone. In this study, we present the structure of Hcp from Acinetobacter baumannii, together with functional and oligomerization studies. The structure of this protein exhibits a tight β barrel formed by two β sheets and flanked at one side by a short α-helix. Six Hcp molecules associate to form a donut-shaped hexamer, as observed in both the crystal structure and solution. These results emphasize the importance of this oligomerization state in this family of proteins, despite the low similarity of sequence among them. The structure presented in this study is the first one for a protein forming part of a functional T6SS from A. baumannii. These results will help us to understand the mechanism and function of this secretion system in this opportunistic nosocomial pathogen.

  12. Mutant Prevention Concentrations of Imipenem and Meropenem against Pseudomonas aeruginosa and Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    E. Dahdouh

    2014-01-01

    Full Text Available The aim of this study was to determine the usefulness of the MPC of carbapenems against clinical isolates of Pseudomonas spp. and Acinetobacter spp. and to assess its possible relationship with mechanisms of resistance. Detection of the mechanisms of resistance was performed using Antibiotic Susceptibility Testing, Double Disk Synergy, disk antagonism, addition of NaCl to the medium, addition of PBA or EDTA to Carbapenem disks, addition of PBA to Cefoxitin disks, and CCCP test for 10 Pseudomonas spp. and Acinetobacter baumannii strains. The MIC and MPC were determined using the broth macrodilution and plate dilution methods, respectively. Four Acinetobacter baumannii strains produced MBL. Two of them produced Oxacillinase and one produced ESBL. Two Pseudomonas spp. isolates produced both KPC and MBL. The resistant Acinetobacter spp. and Pseudomonas spp. strains had higher MPC values than susceptible ones. However, the Mutant Selection Window was found to be dependent on the degree of resistance but not on a particular mechanism of resistance. The usefulness of the MPC was found to be dependent on its value. Based on our data, we recommend determining the MPC for each isolate before using it during treatment. Furthermore, the use of T>MSW instead of T>MIC is suggested.

  13. Characterisation and genome sequence of the lytic Acinetobacter baumannii bacteriophage vB_AbaS_Loki.

    Directory of Open Access Journals (Sweden)

    Dann Turner

    Full Text Available Acinetobacter baumannii has emerged as an important nosocomial pathogen in healthcare and community settings. While over 100 of Acinetobacter phages have been described in the literature, relatively few have been sequenced. This work describes the characterisation and genome annotation of a new lytic Acinetobacter siphovirus, vB_AbaS_Loki, isolated from activated sewage sludge. Sequencing revealed that Loki encapsulates a 41,308 bp genome, encoding 51 predicted open reading frames. Loki is most closely related to Acinetobacter phage IME_AB3 and more distantly related to Burkholderia phage KL1, Paracoccus phage vB_PmaS_IMEP1 and Pseudomonas phages vB_Pae_Kakheti25, vB_PaeS_SCH_Ab26 and PA73. Loki is characterised by a narrow host range, among the 40 Acinetobacter isolates tested, productive infection was only observed for the propagating host, A. baumannii ATCC 17978. Plaque formation was found to be dependent upon the presence of Ca2+ ions and adsorption to host cells was abolished upon incubation with a mutant of ATCC 17978 encoding a premature stop codon in lpxA. The complete genome sequence of vB_AbaS_Loki was deposited in the European Nucleotide Archive (ENA under the accession number LN890663.

  14. Purification, crystallization and preliminary X-ray crystallographic analysis of diaminopimelate epimerase from Acinetobacter baumannii

    International Nuclear Information System (INIS)

    Park, Jeong Soon; Lee, Woo Cheol; Song, Jung Hyun; Kim, Seung Il; Lee, Je Chul; Cheong, Chaejoon; Kim, Hye-Yeon

    2012-01-01

    The crystallization and preliminary X-ray crystallographic analysis of diaminopimelate epimerase from A. baumannii are reported. The meso isomer of diaminopimelate (meso-DAP) is a biosynthetic precursor of l-lysine in bacteria and plants, and is a key component of the peptidoglycan layer in the cell walls of Gram-negative and some Gram-positive bacteria. Diaminopimelate epimerase (DapF) is a pyridoxal-5′-phosphate-independent racemase which catalyses the interconversion of (6S,2S)-2,6-diaminopimelic acid (ll-DAP) and meso-DAP. In this study, DapF from Acinetobacter baumannii was overexpressed in Escherichia coli strain SoluBL21, purified and crystallized using a vapour-diffusion method. A native crystal diffracted to a resolution of 1.9 Å and belonged to space group P3 1 or P3 2 , with unit-cell parameters a = b = 74.91, c = 113.35 Å, α = β = 90, γ = 120°. There were two molecules in the asymmetric unit

  15. Comparison of molecular typing methods for the analyses of Acinetobacter baumannii from ICU patients.

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    Johnson, J Kristie; Robinson, Gwen L; Zhao, LiCheng; Harris, Anthony D; Stine, O Colin; Thom, Kerri A

    2016-12-01

    Acinetobacter baumannii has emerged as an important cause of healthcare-associated infections causing great morbidity and mortality. Despite its clinical importance, it is still unknown which molecular typing method is the best to determine or confirm institutional outbreaks as well as to identify epidemiologically related isolates from different geographical areas. To determine the most discriminatory molecular typing method, we isolated A. baumannii from perianal swabs collected from intensive care unit (ICU) patients in a cohort study during 2002 and 2008. Strains from each year were analyzed by pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST), and multi-locus variable-number tandem repeat analysis (MLVA). Genetic relatedness of the isolates was consistent between PFGE and MLST as well as between analyses of loci containing MLVA and MLST. Our data show that PFGE and MLVA are similar when discriminating between isolates and are both good methods to use when questioning whether two isolates are indistinguishable. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Species identification within Acinetobacter calcoaceticus-baumannii complex using MALDI-TOF MS.

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    Toh, Benjamin E W; Paterson, David L; Kamolvit, Witchuda; Zowawi, Hosam; Kvaskoff, David; Sidjabat, Hanna; Wailan, Alexander; Peleg, Anton Y; Huber, Charlotte A

    2015-11-01

    Acinetobacter baumannii, one of the more clinically relevant species in the Acinetobacter genus is well known to be multi-drug resistant and associated with bacteremia, urinary tract infection, pneumonia, wound infection and meningitis. However, it cannot be differentiated from closely related species such as Acinetobacter calcoaceticus, Acinetobacter pittii and Acinetobacter nosocomialis by most phenotypic tests and can only be differentiated by specific, time consuming genotypic tests with very limited use in clinical microbiological laboratories. As a result, these species are grouped into the A. calcoaceticus-A. baumannii (Acb) complex. Herein we investigated the mass spectra of 73 Acinetobacter spp., representing ten different species, using an AB SCIEX 5800 MALDI-TOF MS to differentiate members of the Acinetobacter genus, including the species of the Acb complex. RpoB gene sequencing, 16S rRNA sequencing, and gyrB multiplex PCR were also evaluated as orthogonal methods to identify the organisms used in this study. We found that whilst 16S rRNA and rpoB gene sequencing could not differentiate A. pittii or A. calcoaceticus, they can be differentiated using gyrB multiplex PCR and MALDI-TOF MS. All ten Acinetobacter species investigated could be differentiated by their MALDI-TOF mass spectra. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Types and prevalence of carbapenem-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex in Northern Taiwan.

    Science.gov (United States)

    Hsieh, Wen-Shyang; Wang, Nai-Yu; Feng, Jou-An; Weng, Li-Chuan; Wu, Hsueh-Hsia

    2014-01-01

    The frequency of the carbapenem-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii (CRACB) complex increases annually in our hospitals. However, the types and prevalence of carbapenemases among isolates still remain unclear. In this study, we identified and collected 672 carbapenem-resistant isolates from a medical center in Northern Taiwan between April and December of 2010. There were 577 genospecies 2 (Acinetobacter baumannii), 79 genospecies 13TU, and 16 genospecies 3 isolates. The isolates had an acquired blaOXA-24-like gene, which was confirmed by sequencing for the encoded OXA-72 carbapenemase, and were often associated with high-level carbapenem resistance. These CRACB complex isolates remained susceptible to colistin (100%). The genotyping of isolates was conducted using pulsed-field gel electrophoresis with ApaI digestion. In most clonally related groups, patients were from both branch hospitals. The results indicate that interhospital dissemination of clones occurred. This study provides updated data on the types and prevalence of the CRACB complex. In addition, it presents a warning on the emergence and spread of CRACB complex harboring blaOXA-24-like genes in northern Taiwan.

  18. Silver Nanocomposite Biosynthesis: Antibacterial Activity against Multidrug-Resistant Strains of Pseudomonas aeruginosa and Acinetobacter baumannii

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    Klebson Silva Santos

    2016-09-01

    Full Text Available Bacterial resistance is an emerging public health issue that is disseminated worldwide. Silver nanocomposite can be an alternative strategy to avoid Gram-positive and Gram-negative bacteria growth, including multidrug-resistant strains. In the present study a silver nanocomposite was synthesized, using a new green chemistry process, by the addition of silver nitrate (1.10−3 mol·L−1 into a fermentative medium of Xanthomonas spp. to produce a xanthan gum polymer. Transmission electron microscopy (TEM was used to evaluate the shape and size of the silver nanoparticles obtained. The silver ions in the nanocomposite were quantified by flame atomic absorption spectrometry (FAAS. The antibacterial activity of the nanomaterial against Escherichia coli (ATCC 22652, Enterococcus faecalis (ATCC 29282, Pseudomonas aeruginosa (ATCC 27853 and Staphylococcus aureus (ATCC 25923 was carried out using 500 mg of silver nanocomposite. Pseudomonas aeruginosa and Acinetobacter baumannii multidrug-resistant strains, isolated from hospitalized patients were also included in the study. The biosynthesized silver nanocomposite showed spherical nanoparticles with sizes smaller than 10 nm; 1 g of nanocomposite contained 49.24 µg of silver. Multidrug-resistant strains of Pseudomonas aeruginosa and Acinetobacter baumannii, and the other Gram-positive and Gram-negative bacteria tested, were sensitive to the silver nanocomposite (10–12.9 mm of inhibition zone. The biosynthesized silver nanocomposite seems to be a promising antibacterial agent for different applications, namely biomedical devices or topical wound coatings.

  19. Molecular evaluation of colistin-resistant gene expression changes in Acinetobacter baumannii with real-time polymerase chain reaction

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    Sepahvand S

    2017-11-01

    Full Text Available Shahriar Sepahvand,1 Mohammad Ali Davarpanah,2 Amir Roudgari,3 Abbas Bahador,4 Vajihe Karbasizade,5 Zahra Kargar Jahromi6 1Department of Microbiology, Falavarjan Branch, Islamic Azad University, Isfahan, Iran; 2Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran; 3Shiraz Trauma Center, Shiraz University of Medical Sciences, Shiraz, Iran; 4Department of Microbiology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran; 5Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran; 6Zoonoses Research Center, Jahrom University of Medical Sciences, Jahrom, Iran Background: Acinetobacter baumannii is an important human pathogen which has recently gained increased attention due to the occurrence of drug-resistant nosocomial infections in patients suffering from immune system disorders, and those in hospital intensive care units. The aim of this research was to identify and isolate A. baumannii strains resistant to colistin, determine antibiotic resistance pattern of this bacteria, investigate the presence of colistin-resistant genes, and finally assess the effect of expression changes in pmrA and pmrB genes resistant to A. baumannii against colistin via real-time polymerase chain reaction.Methods: The samples were initially purified and isolated using biochemical tests and Microgen kit. Later, the resistance pattern evaluation of validated samples to different antibiotics and colistin was carried out using two methods viz., disc diffusion and E-test. This was followed by the assessment of genes resistant to colistin via polymerase chain reaction besides gene expression changes via real-time polymerase chain reaction. Results: The results of this study indicated that eleven strains of A. baumannii isolated from Shahid Rajaee Trauma Hospital were resistant to colistin. However, in the resistance pattern evaluation of A. baumannii isolated

  20. Pneumonia caused by extensive drug-resistant Acinetobacter baumannii among hospitalized patients: genetic relationships, risk factors and mortality.

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    Li, Yu Jun; Pan, Chu Zhi; Fang, Chang Quan; Zhao, Zhu Xiang; Chen, Hui Ling; Guo, Peng Hao; Zhao, Zi Wen

    2017-05-30

    The clonal spread of multiple drug-resistant Acinetobacter baumannii is an emerging problem in China. We analysed the molecular epidemiology of Acinetobacter baumanni isolates at three teaching hospitals and investigated the risk factors, clinical features, and outcomes of hospital-acquired pneumonia caused by extensive drug-resistant Acinetobacter baumannii (XDRAB) infection in Guangzhou, China. Fifty-two A. baumannii isolates were collected. Multilocus sequence typing (MLST) was used to assess the genetic relationships among the isolates. The bla OXA-51-like gene was amplified using polymerase chain reaction (PCR) and sequencing. The resistance phenotypes were determined using the disc diffusion method. A retrospective case-control study was performed to determine factors associated with XDRAB pneumonia. Most of the 52 A. baumannii isolates (N = 37, 71.2%) were collected from intensive care units (ICUs). The respiratory system was the most common bodily site from which A. baumannii was recovered (N = 45, 86.5%). Disc diffusion classified the isolates into 17 multidrug-resistant (MDR) and 35 extensively drug-resistant (XDR) strains. MLST grouped the A. baumannii isolates into 5 existing sequence types (STs) and 7 new STs. ST195 and ST208 accounted for 69.2% (36/52) of the isolates. The clonal relationship analysis showed that ST195 and ST208 belonged to clonal complex (CC) 92. According to the sequence-based typing (SBT) of the bla OXA-51-like gene, 51 A. baumannii isolates carried OXA-66 and the rest carried OXA-199. There were no significant differences with respect to the resistance phenotype between the CC92 and non-CC92 strains (P = 0.767). The multivariate analysis showed that the APACHE II score, chronic obstructive pulmonary disease (COPD) and cardiac disease were independent risk factors for XDRAB pneumonia (P < 0.05). The mortality rate of XDRAB pneumonia was high (up to 42.8%), but pneumonia caused by XDRAB was not associated with in

  1. Expanding nail or expanding femur? An adverse event with the expandable intramedullary nail.

    Science.gov (United States)

    Gangopadhyay, Soham; Riley, Nicholas D; Sivaji, Chellappan K

    2010-01-01

    The expandable intramedullary nail is self-locking and has the advantage of reducing operating time and exposure to ionizing radiation. The nail is recommended for simple diaphyseal fractures involving the middle third of long bones, where the nail can bypass the fracture site by at least 5 cm. We encountered a unique complication with the expandable nail in a simple transverse shaft fracture at the junction of the middle and distal third of the left femur in an otherwise healthy 57-year-old man. The fracture was reduced and a 12-mm expandable nail was inserted. Following full expansion, intraoperative radiographs were obtained prior to closure. After six postoperative weeks, it was noted that the nail expanded the femoral canal, converting a simple fracture to a distally progressing comminuted fracture with a butterfly fragment. A review of the intraoperative radiographs showed slight widening of the medullary canal at the level of the fracture. As the alignment was satisfactory and callus was present, no further surgical intervention was considered. The patient was advised not to bear weight and was provided with a locked knee brace in extension to wear for six weeks. Radiographs at 12 weeks demonstrated good progress of healing with adequate callus and the patient was permitted to bear weight as tolerated and commence knee flexion. The fracture united satisfactorily at four months. This adverse experience emphasizes that caution should be exercised when expanding the nail, with close observation of the medullary canal diameter during the later stages of expansion.

  2. [Evaluation of the efficacy of colistin/sulbactam combination on carbapenem-resistant Acinetobacter baumannii strains].

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    Çetinkol, Yeliz; Telli, Murat; Altunçekiç Yıldırım, Arzu; Çalgın, Mustafa Kerem

    2016-07-01

    Acinetobacter baumannii strains, are opportunistic pathogens that cause severe nosocomial infections that are difficult to treat due to development of resistance to multiple antibiotics. As the antibiotic choices to be used in treatment are limited, combinations of a variety of antibiotics are used. The aims of this study were to identify the minimal inhibitory concentration (MIC) values of colistin and sulbactam against A.baumannii isolates and to determine the in vitro activity of colistin-sulbactam combination. A total of 50 A.baumannii strains isolated from different clinical specimens (32 tracheal aspirates, 10 blood, 6 urine and 2 wound samples) were included in the study. The identification of bacteria was performed by traditional methods and Vitek-2 (BioMerieux, France) automated system. Antibiotic susceptibilities were detected by Mueller-Hinton agar disk diffusion method and Vitek-2 automated system and the results were interpreted according to the CLSI standards. MIC values of colistin and sulbactam against A.baumannii strains and in vitro interactions of colistin-sulbactam combinations were determined with the E-test (BioMerieux, France). Fractional inhibitory concentration (FIC) index was used for the detection of efficacy of drug combinations. The presence of oxacillinase and metallo-beta-lactamase (MBL) genes that lead carbapenem resistance was investigated by polymerase chain reaction (PCR), and pulsed-field gel electrophoresis (PFGE) was performed for the determination of clonal relationship. In our study, all strains (100%) were detected as susceptible to colistin, 48 (96%) to trimethoprim/sulphamethoxazole and 18 to (36%) tigecyclin; however all of them were resistant to the other studied antibiotics, including sulbactam and carbapenem. When the colistin-sulbactam combination was assessed according to FIC index, all strains were found to have antagonistic effect. All of the carbapenem-resistant strains were positive for OXA-51 and OXA-23, and 3

  3. In vitro effects of tigecycline in combination with colistin (polymyxin E) and sulbactam against multidrug-resistant Acinetobacter baumannii.

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    Ni, Wentao; Cui, Junchang; Liang, Beibei; Cai, Yun; Bai, Nan; Cai, Xuejiu; Wang, Rui

    2013-12-01

    The lack of active antimicrobial agents against multidrug-resistant (MDR) Acinetobacter baumannii has posed great threat to the public health. Combination therapies with antibiotics owning different antimicrobial mechanisms have been proposed as good options for treating MDR A. baumannii infections. This study was aimed to investigate the in vitro effects of tigecycline in combination with colistin and sulbactam against MDR A. baumannii. A total of 70 strains from two hospitals in China were examined in the study. The checkerboard method was used for determining synergistic activity of different antibiotic combinations. Tigecycline/colistin combination displayed synergistic and partial synergistic activity in 24.3% of the isolates, whereas the tigecycline/sulbactam combination showed synergistic and partial synergistic activity in 64.3% of the isolates. Neither of the combinations showed antagonism in this study. In addition, for evaluating the ability of combinations on resistance prevention, mutant prevention concentrations (MPCs) of tigecycline, colistin, sulbactam alone and tigecycline in combination with colistin and sulbactam were studied against MDR A. baumannii. Compared with tigecycline used alone, combination therapies could achieve lower MPCs of tigecycline. However, when the MPCs of dual-drug therapy were in conjunction with clinical pharmacokinetic profiles, combinations may not strictly curb the occurrence of resistance at current dosage regimen. In summary, this study suggested that combination therapy was a good option for treating MDR A. baumannii infections. But the finding that combination with these drugs at current dosage regimen may not prevent emergence of resistance warranted further studies on dosage of combined antibiotics required for achieving resistance prevention.

  4. Fomite-fingerpad transfer efficiency (pick-up and deposit) of Acinetobacter baumannii-with and without a latex glove.

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    Greene, Christine; Vadlamudi, Gayathri; Eisenberg, Marisa; Foxman, Betsy; Koopman, James; Xi, Chuanwu

    2015-09-01

    Acinetobacter baumannii is a significant health care-associated pathogen because it is easily transmitted via fomites, extremely difficult to eradicate from the environment, and highly drug resistant. Understanding the environmentally mediated transmission dynamics of A baumannii is critical for more effective infection control. However, transfer efficiency of pathogen pick-up and deposit remains poorly understood. Our study estimates the transfer efficiency of A baumannii with and without latex glove use from the fingerpad to a fomite and from a fomite to the fingerpad. Fomite-fingerpad transfer efficiencies were determined for 6 materials (glass, stainless steel, porcelain, polypropylene, polycarbonate, and rubber). For A baumannii, the fomite-to-fingerpad transfer efficiency was 24.1%, and the fingerpad-to-fomite transfer efficiency was 5.6%. When latex gloves were worn, the fomite-to-fingerpad transfer efficiency was reduced by 55.9% (to 10.6%) and the fingerpad-to-fomite transfer efficiency was reduced by 47.1% (to 3.0%). The average transfer efficiency between 2 skin surfaces was 32.5%. The fomite-to-fingerpad transfer efficiency of A baumannii was statistically significantly higher than the fingerpad-to-fomite transfer efficiency, regardless of glove use. There was no significant difference in transfer efficiency by material type, except for rubber, which resulted in marginally higher transfer efficiencies. Our results underscore the importance of frequently changing gloves during patient care and frequent handwashing-hand hygiene during bare-handed care for the reduction of pathogen transmission. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  5. Transcriptomic analysis of colistin-susceptible and colistin-resistant isolates identifies genes associated with colistin resistance in Acinetobacter baumannii.

    Science.gov (United States)

    Park, Y K; Lee, J-Y; Ko, K S

    2015-08-01

    The emergence of colistin-resistant Acinetobacter baumannii is concerning, as colistin is often regarded as the last option for treating multidrug-resistant (MDR) A. baumannii infections. Using mRNA sequencing, we compared whole transcriptomes of colistin-susceptible and colistin-resistant A. baumannii strains, with the aim of identifying genes involved in colistin resistance. A clinical colistin-susceptible strain (06AC-179) and a colistin-resistant strain (07AC-052) were analysed in this study. In addition, a colistin-resistant mutant (06AC-179-R1) derived from 06AC-179 was also included in this study. High throughput mRNA sequencing was performed with an Illumina HiSeq TM 2000. In total, six genes were identified as associated with colistin resistance in A. baumannii. These six genes encode PmrAB two-component regulatory enzymes, PmrC (a lipid A phosphoethanolamine transferase), a glycosyltransferase, a poly-β-1,6-N-acetylglucosamine deacetylase, and a putative membrane protein. Matrix-assisted laser desorption/ionization time of flight mass spectrometry revealed that all three colistin-resistant strains used in this study had modified lipid A structure by addition of phosphoethanolamine. As genes found in our results are all associated with either lipopolysaccharide biosynthesis or electrostatic changes in the bacterial cell membrane, lipopolysaccharide modification might be one of the principal modes of acquisition of colistin resistance in some A. baumannii strains. Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  6. Bioprospecting of marine Streptomycetes sp. for its antagonistic activity on MDR Pseudomonas aeruginosa and Acinetobacter baumannii isolates

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    Shanthi John

    2014-02-01

    Full Text Available Objective: To assess the antimicrobial activity of the Actinobacteria bioactive secondary metabolite and characterize the drug resistance mechanisms of Pseudomonas aeruginosa (P. aeruginosa and Acinetobacter baumannii (A. baumannii. Methods: Potential marine Actinobacteria were isolated and the crude extract was purified using thin layer chromatography, the fractions were tested for antimicrobial activity and phylogeny of the selected strain was analyzed. Isolated pathogenic strains were screened for extended spectrum beta-lactamase, mannan-binding lectin, AmpC production, efflux mechanism and polymerase chain reaction. The cephalosporin and carbapenem antibiotics were synergistically tested along with Streptomyces sp. PM49 fraction by combination disc test and double-disc synergy test. Heterogeneous susceptibility assay, minimum inhibitory concentration and expression of DnaK (Hsp70 were determined. Results: Streptomyces sp. PM49 active fraction of Rfvalue 0.69 showed antimicrobial activity and an inhibitory zone of 15 to 7 mm obtained. About 34.1% of P. aeruginosa and 4.8% of A. baumannii were multiple drug resistant. AmpC β-lactamase was found in 12% of A. baumannii, efflux mechanism was putatively positive in 8/23 of P. aeruginosa and 3/20 of A. baumannii. Combination disc test and double-disc synergy test with both PM49 compound and antibiotics showed an increase in the inhibitory zone of <3 mm to 4 mm, three P. aeruginosa isolates expressed blaIMP. Heteroresistant subcolonies grew at a frequency of 3 ×10-5 to 1 ×10-5. Stress induction analysis showed increase of DnaK during heat shock at 52 °C, the levels of protein doubled after exposure to the antibiotics. Conclusions: Novel unexplored Streptomyces spp. antimicrobial constituents can be developed as an inhibitor and can be substituted along with the available antibiotics to combat the drug resistant pathogens.

  7. 5-Episinuleptolide Decreases the Expression of the Extracellular Matrix in Early Biofilm Formation of Multi-Drug Resistant Acinetobacter baumannii

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    Sung-Pin Tseng

    2016-07-01

    Full Text Available Nosocomial infections and increasing multi-drug resistance caused by Acinetobacter baumannii have been recognized as emerging problems worldwide. Moreover, A. baumannii is able to colonize various abiotic materials and medical devices, making it difficult to eradicate and leading to ventilator-associated pneumonia, and bacteremia. Development of novel molecules that inhibit bacterial biofilm formation may be an alternative prophylactic option for the treatment of biofilm-associated A. baumannii infections. Marine environments, which are unlike their terrestrial counterparts, harbor an abundant biodiversity of marine organisms that produce novel bioactive natural products with pharmaceutical potential. In this study, we identified 5-episinuleptolide, which was isolated from Sinularia leptoclados, as an inhibitor of biofilm formation in ATCC 19606 and three multi-drug resistant A. baumannii strains. In addition, the anti-biofilm activities of 5-episinuleptolide were observed for Gram-negative bacteria but not for Gram-positive bacteria, indicating that the inhibition mechanism of 5-episinuleptolide is effective against only Gram-negative bacteria. The mechanism of biofilm inhibition was demonstrated to correlate to decreased gene expression from the pgaABCD locus, which encodes the extracellular polysaccharide poly-β-(1,6-N-acetylglucosamine (PNAG. Scanning electron microscopy (SEM indicated that extracellular matrix of the biofilm was dramatically decreased by treatment with 5-episinuleptolide. Our study showed potentially synergistic activity of combination therapy with 5-episinuleptolide and levofloxacin against biofilm formation and biofilm cells. These data indicate that inhibition of biofilm formation via 5-episinuleptolide may represent another prophylactic option for solving the persistent problem of biofilm-associated A. baumannii infections.

  8. Integron types, gene cassettes and antimicrobial resistance profile of Acinetobacter baumannii isolated from BAL samples in Babol, north of Iran.

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    Akrami, Fariba; Shahandashti, Elaheh Ferdosi; Yahyapour, Yousef; Sadeghi, Mohsen; Khafri, Soraya; Pournajaf, Abazar; Rajabnia, Ramazan

    2017-08-01

    Multi-drug resistant isolates of Acinetobacter baumannii have created therapeutic problems worldwide. This current study was intended to determine the Integron types, gene cassettes and antimicrobial resistance profile of A. baumannii isolated from BAL samples in Babol, north of Iran. During a 15-month period, 35 A. baumannii isolates were studied. Different classes of antimicrobial agents were used to determine the resistance ratios. Multiplex-PCR was used to detect different types of integrons and associated gene cassettes. The resistance rates to GM, FEP, AK, TOB, CP, PIP, SAM, IPM, SXT, CTX, CAZ, CL, TIM, MEM, and TZP were 85.7%, 100%, 91.4%, 68.5%, 94.3%, 88.5%, 97.1%, 94.3%, 100%, 100%, 100%, 0.0%, 91.4%, 94.3% and 91.4%, respectively. The distribution analysis of int genes showed that 25.7%, 88.6% and 28.6% of isolates carried the intI, intII and intIII genes, respectively. The prevalence of aadB, dfrA1, bla-OXA 30 and aadA1 genes were 94.3%, 77.1%, 40% and 5.7%, respectively. The current study showed that a high level of A. baumannii isolates harbor integrons in our therapeutic center, which may lead to distribution of multiple antimicrobial resistance. The different types of gene cassette arrays in the present study highlight the important role of geographical features in MDR isolates dissemination which could be credited to different profiles of drug consumption in different areas. The findings emphasized that the need for continuous surveillance to prevent distribution of multidrug resistance among A. baumannii strains in Iran. Copyright © 2017. Published by Elsevier Ltd.

  9. High prevalence of extensively drug-resistant and metallo beta-lactamase-producing clinical Acinetobacter baumannii in Iran.

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    Maspi, Hossein; Mahmoodzadeh Hosseini, Hamideh; Amin, Mohsen; Imani Fooladi, Abbas Ali

    2016-09-01

    Acinetobacter species particularly Acinetobacter baumannii (A. baumannii) have been widely reported as broad-spectrum antibiotic resistant pathogens. Expression of various types of metallo beta-lactamases (MBL), classified as Ambler class B, has been associated with carbapenem resistance. Here, we attempted to assess the frequency of extensively drug-resistant (XDR) and MBL-producing A. baumannii among clinical isolates. 86 clinical A. baumannii strains were collected from 2014 to 2015 and their susceptibility to meropenem (10 μg), imipenem (10 μg), azteronem (30 μg), pipracillin (100 μg) tazobactam (110 μg), tobramycin (10 μg), fosfomycin (200 μg), rifampicin (5 μg), colistin (10 μg), tigecycline (15 μg), sulbactam/ampicillin (10 μg + 10 μg) and polymixin B (300 U) was evaluated using disk diffusion method. The MBL-producing isolates were screened using combined disc diffusion method. Furthermore, the presence of blaVIM, blaIMP, blaSPM, blaGIM, blaSIM and blaNDM was detected by PCR. 34.9% of isolates were recovered from bronchoalveolar lavage (BAL). 81 (94.2%) and 62 (71.2%) isolates were multidrug resistance (MDR) and XDR, respectively. 44 (51.2%) and 65 (75.6%) isolates were MBL-producing strains with resistance to imipenem and meropenem, respectively. 2 (2.3%), 13 (15.1%), 2 (2.3%), 4 (4.7%) and 2 (2.3%) isolates carried blaVIM, blaIMP, blaSPM, blaGIM and blaSIM genes, respectively. Our data showed that the rate of XDR and MBL A. baumannii is on the rise. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Blue light irradiation triggers the antimicrobial potential of ZnO nanoparticles on drug-resistant Acinetobacter baumannii.

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    Yang, Ming-Yeh; Chang, Kai-Chih; Chen, Liang-Yu; Wang, Po-Ching; Chou, Chih-Chiang; Wu, Zhong-Bin; Hu, Anren

    2018-03-01

    Photodynamic inactivation (PDI) is a non-invasive and safe therapeutic method for microbial infections. Bacterial antibiotic resistance is caused by antibiotics abuse. Drug-resistant Acinetobacter spp. is a serious problem in hospitals around the world. These pathogens from nosocomial infections have high mortality rates in frailer people, and Acinetobacter spp. is commonly found in immunocompromised patients. Visible light is safer than ultraviolet light (UV) for PDI of nosocomial pathogens with mammalian cells. Zinc oxide nanoparticles (ZnO-NPs) were used in this study as an antimicrobial agent and a photosensitizer. ZnO is recognized as safe and has extensive usage in food additives, medical and cosmetic products. In this study, we used 0.125 mg/ml ZnO-NPs combined with 10.8 J/cm 2 blue light (BL) on Acinetobacter baumannii (A. baumannii) that could significantly reduce microbial survival. However, individual exposure to ZnO-NPs does not affect the viability of A. baumannii. BL irradiation could trigger the antimicrobial ability of ZnO nanoparticles on A. baumannii. The mechanism of photocatalytic ZnO-NPs treatment for sterilization occurs through bacterial membrane disruptions. Otherwise, the photocatalytic ZnO-NPs treatment showed high microbial eradication in nosocomial pathogens, including colistin-resistant and imipenem-resistant A. baumannii and Klebsiella pneumoniae. Based on our results, the photocatalytic ZnO-NPs treatment could support hygiene control and clinical therapies without antibiotics to nosocomial bacterial infections. Copyright © 2018. Published by Elsevier B.V.

  11. In vitro and in vivo analysis of antimicrobial agents alone and in combination against multi-drug resistant Acinetobacter baumannii

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    Songzhe eHE

    2015-05-01

    Full Text Available Objective To investigate the in vitro and in vivo antibacterial activities of tigecycline and other 13 common antimicrobial agents, alone or in combination, against multi-drug resistant Acinetobacter baumannii.MethodsAn in vitro susceptibility test of 101 Acinetobacter baumannii was used to detect minimal inhibitory concentrations (MICs. A mouse lung infection model of multi-drug resistant Acinetobacter baumannii,established by the ultrasonic atomization method, was used to define in vivo antimicrobial activities.Results Multi-drug resistant Acinetobacter baumannii showed high sensitivity to tigecycline (98% inhibition, polymyxin B (78.2% inhibition, and minocycline (74.2% inhibition. However, the use of these antimicrobial agents in combination with other antimicrobial agents produced synergistic or additive effects. In vivo data showed that white blood cell (WBC counts in drug combination groups C (minocycline + amikacin and D (minocycline + rifampicin were significantly higher than in groups A (tigecycline and B (polymyxin B (P < 0.05, after administration of the drugs 24h post-infection. Lung tissue inflammation gradually increased in the model group during the first 24h after ultrasonic atomization infection; vasodilation, congestion with hemorrhage were observed 48h post infection. After three days of anti-infective therapy in groups A, B, C and D, lung tissue inflammation in each group gradually recovered with clear structures. The mortality rates in drug combination groups (groups C and D were much lower than in groups A and B.ConclusionThe combination of minocycline with either rifampicin or amikacin is more effective against multidrug-resistant Acinetobacter baumannii than single-agent tigecycline or polymyxin B. In addition, the mouse lung infection by ultrasonic atomization is a suitable model for drug screening and analysis of infection mechanism.

  12. Emergence in Taiwan of novel imipenem-resistant Acinetobacter baumannii ST455 causing bloodstream infection in critical patients.

    Science.gov (United States)

    Lee, Hao-Yuan; Huang, Chih-Wei; Chen, Chyi-Liang; Wang, Yi-Hsin; Chang, Chee-Jen; Chiu, Cheng-Hsun

    2015-12-01

    Acinetobacter baumannii is one of the most important nosocomial pathogens worldwide. This study aimed to use multilocus sequence typing (MLST) for the epidemiological surveillance of A. baumannii isolates in Taiwan and analyze the clinical presentations and patients' outcome. MLST according to both Bartual's PubMLST and Pasteur's MLST schemes was applied to characterize bloodstream imipenem-resistant A. baumannii (IRAB) infection in intensive care units in a medical center. A total of 39 clinical IRAB bloodstream isolates in 2010 were enrolled. We also collected 13 imipenem-susceptible A. baumannii (ISAB) bloodstream isolates and 30 clinical sputum isolates (24 IRAB and 6 ISAB) for comparison. Clinical presentations and outcome of the patients were analyzed. We found that infection by ST455(B)/ST2(P) and inappropriate initial therapy were statistically significant risk factors for mortality. More than one-third of the IRAB isolates belonged to ST455(B)/ST2(P). Most ST455(B)/ST2(P) (80%) carried ISAba1-blaOXA-23, including 10 (66.7%) with Tn2006 (ISAba1-blaOXA-23-ISAba1) in an AbaR4-type resistance island. ST455(B)/ST2(P) appears to evolve from ST208(B)/ST2(P) of clonal complex (CC) 92(B)/CC2(P). In this hospital-based study, A. baumannii ST455 accounted for 38.5% of IRAB bacteremia, with a high mortality of 86.7%. Approximately 85% of ST455(B)/ST2(P)bacteremia had a primary source of ventilation-associated pneumonia. We report the emergence in Taiwan of IRAB ST455(B)/ST2(P), which is the current predominant clone of IRAB in our hospital and has been causing bacteremia with high mortality in critical patients. Copyright © 2015. Published by Elsevier B.V.

  13. Expanding the eukaryotic genetic code

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2017-02-28

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  14. Expanding the eukaryotic genetic code

    Science.gov (United States)

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2013-01-22

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  15. Re-sensitizing Multidrug Resistant Bacteria to Antibiotics by Targeting Bacterial Response Regulators: Characterization and Comparison of Interactions between 2-Aminoimidazoles and the Response Regulators BfmR from Acinetobacter baumannii and QseB from Francisella spp.

    Science.gov (United States)

    Milton, Morgan E.; Minrovic, Bradley M.; Harris, Danni L.; Kang, Brian; Jung, David; Lewis, Caleb P.; Thompson, Richele J.; Melander, Roberta J.; Zeng, Daina; Melander, Christian; Cavanagh, John

    2018-01-01

    2-aminoimidazole (2-AI) compounds inhibit the formation of bacterial biofilms, disperse preformed biofilms, and re-sensitize multidrug resistant bacteria to antibiotics. 2-AIs have previously been shown to interact with bacterial response regulators, but the mechanism of interaction is still unknown. Response regulators are one part of two-component systems (TCS). TCSs allow cells to respond to changes in their environment, and are used to trigger quorum sensing, virulence factors, and antibiotic resistance. Drugs that target the TCS signaling process can inhibit pathogenic behavior, making this a potent new therapeutic approach that has not yet been fully exploited. We previously laid the groundwork for the interaction of the Acinetobacter baumannii response regulator BfmR with an early 2-AI derivative. Here, we further investigate the response regulator/2-AI interaction and look at a wider library of 2-AI compounds. By combining molecular modeling with biochemical and cellular studies, we expand on a potential mechanism for interaction between response regulators and 2-AIs. We also establish that Francisella tularensis/novicida, encoding for only three known response regulators, can be a model system to study the interaction between 2-AIs and response regulators. We show that knowledge gained from studying Francisella can be applied to the more complex A. baumannii system, which contains over 50 response regulators. Understanding the impact of 2-AIs on response regulators and their mechanism of interaction will lead to the development of more potent compounds that will serve as adjuvant therapies to broad-range antibiotics. PMID:29487854

  16. Re-sensitizing Multidrug Resistant Bacteria to Antibiotics by Targeting Bacterial Response Regulators: Characterization and Comparison of Interactions between 2-Aminoimidazoles and the Response Regulators BfmR from Acinetobacter baumannii and QseB from Francisella spp.

    Directory of Open Access Journals (Sweden)

    Morgan E. Milton

    2018-02-01

    Full Text Available 2-aminoimidazole (2-AI compounds inhibit the formation of bacterial biofilms, disperse preformed biofilms, and re-sensitize multidrug resistant bacteria to antibiotics. 2-AIs have previously been shown to interact with bacterial response regulators, but the mechanism of interaction is still unknown. Response regulators are one part of two-component systems (TCS. TCSs allow cells to respond to changes in their environment, and are used to trigger quorum sensing, virulence factors, and antibiotic resistance. Drugs that target the TCS signaling process can inhibit pathogenic behavior, making this a potent new therapeutic approach that has not yet been fully exploited. We previously laid the groundwork for the interaction of the Acinetobacter baumannii response regulator BfmR with an early 2-AI derivative. Here, we further investigate the response regulator/2-AI interaction and look at a wider library of 2-AI compounds. By combining molecular modeling with biochemical and cellular studies, we expand on a potential mechanism for interaction between response regulators and 2-AIs. We also establish that Francisella tularensis/novicida, encoding for only three known response regulators, can be a model system to study the interaction between 2-AIs and response regulators. We show that knowledge gained from studying Francisella can be applied to the more complex A. baumannii system, which contains over 50 response regulators. Understanding the impact of 2-AIs on response regulators and their mechanism of interaction will lead to the development of more potent compounds that will serve as adjuvant therapies to broad-range antibiotics.

  17. Genotyping and antibiotic resistance of Acinetobacter baumannii strains isolated from patients hospitalized in teaching hospitals of Shahrekord by Pulsed- Field Gel Electrophorsis

    Directory of Open Access Journals (Sweden)

    A Gholipur

    2017-06-01

    Conclusion: Although variations among strains of Acinetobacter baumannii were observed by using PFGE in Shahrekord, but no epidemic strain was detected among them. In terms of resistance to commonly used antibiotics were also different patterns.

  18. Clinical and microbiological characteristics of OXA-23- and OXA-143-producing Acinetobacter baumannii in ICU patients at a teaching hospital, Brazil

    Directory of Open Access Journals (Sweden)

    Francelli Cordeiro Neves

    2016-11-01

    Conclusions: In this study, clonally unrelated OXA-123- and OXA-143-producing A. baumannii strains in ICU patients were strongly correlated to colonization with infected patients being associated with a poor outcome.

  19. In vitro activity of colistin in antimicrobial combination against carbapenem-resistant Acinetobacter baumannii isolated from patients with ventilator-associated pneumonia in Vietnam.

    Science.gov (United States)

    Le Minh, Vien; Thi Khanh Nhu, Nguyen; Vinh Phat, Voong; Thompson, Corinne; Huong Lan, Nguyen Phu; Thieu Nga, Tran Vu; Thanh Tam, Pham Thi; Tuyen, Ha Thanh; Hoang Nhu, Tran Do; Van Hao, Nguyen; Thi Loan, Huynh; Minh Yen, Lam; Parry, Christopher M; Trung Nghia, Ho Dang; Campbell, James I; Hien, Tran Tinh; Thwaites, Louise; Thwaites, Guy; Van Vinh Chau, Nguyen; Baker, Stephen

    2015-10-01

    Acinetobacter baumannii has become one of the major infection threats in intensive care units (ICUs) globally. Since 2008, A. baumannii has been the leading cause of ventilator-associated pneumonia (VAP) in our ICU at an infectious disease hospital in southern Vietnam. The emergence of this pathogen in our setting is consistent with the persistence of a specific clone exhibiting resistance to carbapenems. Antimicrobial combinations may be a strategy to treat infections caused by these carbapenem-resistant A. baumannii. Therefore, we assessed potential antimicrobial combinations against local carbapenem-resistant A. baumannii by measuring in vitro interactions of colistin with four antimicrobials that are locally certified for treating VAP. We first performed antimicrobial susceptibility testing and multilocus variable number tandem repeat analysis (MLVA) genotyping on 74 A. baumannii isolated from quantitative tracheal aspirates from patients with VAP over an 18-month period. These 74 isolates could be subdivided into 21 main clusters by MLVA and >80 % were resistant to carbapenems. We selected 56 representative isolates for in vitro combination synergy testing. Synergy was observed in four (7 %), seven (13 %), 20 (36 %) and 38 (68 %) isolates with combinations of colistin with ceftazidime, ceftriaxone, imipenem and meropenem, respectively. Notably, more carbapenem-resistant A. baumannii isolates (36/43; 84 %) exhibited synergistic activity with a combination of colistin and meropenem than carbapenem-susceptible A. baumannii isolates (2/13; 15 %) (P = 0.023; Fisher's exact test). Our findings suggest that combinations of colistin and meropenem should be considered when treating carbapenem-resistant A. baumannii infections in Vietnam, and we advocate clinical trials investigating combination therapy for VAP.

  20. Prevalence and Characterization of Integrons in Multidrug Resistant Acinetobacter baumannii in Eastern China: A Multiple-Hospital Study

    Directory of Open Access Journals (Sweden)

    Jing Chen

    2015-08-01

    Full Text Available Objective: The aim of this multiple-hospital study was to investigate the prevalence of integrons in multidrug-resistant Acinetobacter baumannii (MDRAB in Eastern China, and characterize the integron-integrase genes, so as to provide evidence for the management and appropriate antibiotic use of MDRAB infections. Methods: A total of 425 clinical isolates of A. baumannii were collected from 16 tertiary hospitals in 11 cities of four provinces (Fujian, Jiangsu, Zhejiang and Shandong from January 2009 to June 2012. The susceptibility of A. baumannii isolates to ampicillin/sulbactam, piperacillin/tazobactam, ceftazidime, ceftriaxone, cefepime, aztreonam, meropenem, amikacin, gentamicin, tobramycin, ciprofloxacin, levofloxacin, sulfamethoxazole/trimenthoprim, minocycline and imipenem was tested, and integrons and their gene cassettes were characterized in these isolates using PCR assay. In addition, integron-positive A. baumannii isolates were genotyped using pulsed-field gel electrophoresis (PFGE assay, and intI1 gene cassette was sequenced. Results: intI1 gene was carried in 69.6% of total A. baumannii isolates, while intI2 and intI3 genes were not detected. The prevalence of resistance to ampicillin/sulbactam, piperacillin/tazobactam, ceftazidime, ceftriaxone, cefepime, aztreonam, imipenem, meropenem, amikacin, gentamicin, tobramycin, ciprofloxacin, levofloxacin and sulfamethoxazole/trimenthoprim was significantly higher in integron-positive A. baumannii isolates than in negative isolates (all p values <0.05, while no significant difference was observed in the prevalence of minocycline resistance (p > 0.05. PFGE assay revealed 27 PFGE genotypes and 4 predominant genotypes, P1, P4, P7 and P19. The PFGE genotype P1 contained 13 extensive-drug resistant and 89 non-extensive-drug resistant A. baumannii isolates, while the genotype P4 contained 34 extensive-drug resistant and 67 non-extensive-drug resistant isolates, appearing a significant

  1. [Investigation of OXA type beta-lactamases and PFGE patterns in Acinetobacter baumannii strains resistant to carbapenems].

    Science.gov (United States)

    Keyik, Serafettin; Arslan, Uğur; Türk Dağı, Hatice; Seyhan, Tuba; Fındık, Duygu

    2014-10-01

    Acinetobacter baumannii is an important opportunistic and multidrug-resistant pathogen leading to nosocomial infections. Over the last 10 years, a significant and threatening increase in resistance to carbapenems, mainly due to the dissemination of class D beta-lactamases, has been reported in A.baumannii worldwide. The most common types of beta-lactamases causing carbapenem resistance in A.baumannii are the OXA-23, OXA-24, OXA-40, OXA-58 and OXA-143 type serine beta-lactamases. The aim of this study was to investigate the presence of OXA type beta-lactamases in carbapenem-resistant A.baumannii strains and the clonal relationship between the strains. A total of 105 non-duplicate carbapenem-resistant A.baumannii strains isolated from various clinical samples (68 blood, 18 bronchoalveolar lavage, 13 drainage, 3 urine, 2 cerebrospinal fluid and 1 catheter samples) in the Microbiology Laboratories of Selcuk University, Meram (2009-2012) and Selcuklu (2007-2008) Medical School Hospitals, were included in the study. The isolates were identified by conventional methods and Phoenix 100 BD (BD Diagnostic, USA) and Vitek II (bioMerieux, France) automated systems. Carbapenem susceptibility test was performed by Kirby-Bauer disk diffusion method according to the CLSI standards. bla(OXA 23-like), bla(OXA 24-like), bla(OXA 58-like) and bla(OXA 51-like) genes were amplified by multiplex PCR assay and clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE) using ApaI enzyme. The bla(OXA 51-like) gene was determined in all carbapenem-resistant A.baumannii isolates, while the bla(OXA 23-like) and bla(OXA 58-like) genes were detected in 46.6% and 53.3% of isolates, respectively. However bla(OXA 24-like) gene was not demonstrated in any isolates. bla(OXA 23-like) gene was determined in both Meram and Selcuklu Medical School hospitals, but bla(OXA 58-like) gene was detected only in Meram Medical School hospital. PFGE analysis of the isolates revealed 32 different

  2. Molecular epidemiology of multidrug-resistant Acinetobacter baumannii isolates in a university hospital in Nepal reveals the emergence of a novel epidemic clonal lineage.

    Science.gov (United States)

    Shrestha, Shovita; Tada, Tatsuya; Miyoshi-Akiyama, Tohru; Ohara, Hiroshi; Shimada, Kayo; Satou, Kazuhito; Teruya, Kuniko; Nakano, Kazuma; Shiroma, Akino; Sherchand, Jeevan Bdr; Rijal, Basista Psd; Hirano, Takashi; Kirikae, Teruo; Pokhrel, Bharat Mani

    2015-11-01

    The emergence of multidrug-resistant (MDR) Acinetobacter baumannii has become a serious medical problem worldwide. To clarify the genetic and epidemiological properties of MDR A. baumannii strains isolated from a medical setting in Nepal, 246 Acinetobacter spp. isolates obtained from different patients were screened for MDR A. baumannii by antimicrobial disk susceptibility testing. Whole genomes of the MDR A. baumannii isolates were sequenced by MiSeq™ (Illumina), and the complete genome of one isolate (IOMTU433) was sequenced by PacBio RS II. Phylogenetic trees were constructed from single nucleotide polymorphism concatemers. Multilocus sequence types were deduced and drug resistance genes were identified. Of the 246 Acinetobacter spp. isolates, 122 (49.6%) were MDR A. baumannii, with the majority being resistant to aminoglycosides, carbapenems and fluoroquinolones but not to colistin and tigecycline. These isolates harboured the 16S rRNA methylase gene armA as well as bla(NDM-1), bla(OXA-23) or bla(OXA-58). MDR A. baumannii isolates belonging to clonal complex 1 (CC1) and CC2 as well as a novel clonal complex (CC149) have spread throughout a medical setting in Nepal. The MDR isolates harboured genes encoding carbapenemases (OXA and NDM-1) and a 16S rRNA methylase (ArmA). Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  3. Development and evaluation of a core genome multilocus typing scheme for whole-genome sequence-based typing of Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Paul G Higgins

    Full Text Available We have employed whole genome sequencing to define and evaluate a core genome multilocus sequence typing (cgMLST scheme for Acinetobacter baumannii. To define a core genome we downloaded a total of 1,573 putative A. baumannii genomes from NCBI as well as representative isolates belonging to the eight previously described international A. baumannii clonal lineages. The core genome was then employed against a total of fifty-three carbapenem-resistant A. baumannii isolates that were previously typed by PFGE and linked to hospital outbreaks in eight German cities. We defined a core genome of 2,390 genes of which an average 98.4% were called successfully from 1,339 A. baumannii genomes, while Acinetobacter nosocomialis, Acinetobacter pittii, and Acinetobacter calcoaceticus resulted in 71.2%, 33.3%, and 23.2% good targets, respectively. When tested against the previously identified outbreak strains, we found good correlation between PFGE and cgMLST clustering, with 0-8 allelic differences within a pulsotype, and 40-2,166 differences between pulsotypes. The highest number of allelic differences was between the isolates representing the international clones. This typing scheme was highly discriminatory and identified separate A. baumannii outbreaks. Moreover, because a standardised cgMLST nomenclature is used, the system will allow inter-laboratory exchange of data.

  4. Emergence of rifampicin, tigecycline, and colistin-resistant Acinetobacter baumannii in Iran; spreading of MDR strains of novel International Clone variants.

    Science.gov (United States)

    Bahador, Abbas; Taheri, Mohammad; Pourakbari, Babak; Hashemizadeh, Zahra; Rostami, Hossein; Mansoori, Noormohamad; Raoofian, Reza

    2013-10-01

    Multidrug-resistant Acinetobacter baumannii infections are serious challenges for clinicians because of A. baumannii propensity to acquire resistance to a wide spectrum of antimicrobial agents. In this study, 91 A. baumannii isolates from patients in tertiary intensive care units of three university hospitals in the north, central, and south of Iran were selected and tested for susceptibility to 22 antimicrobials; amplified restriction fragment polymorphism and multiplex polymerase chain reaction methods were used to determine genetic relationships and International Clone (IC) of A. baumannii isolates, respectively. Twenty-four genotypes were identified in A. baumannii isolates. About 91.2% of isolates categorized into 4 distinct clusters; one was more heterogeneous and observed across the three locations. A considerable number of the isolates (27.5%) belonged to the novel IC variant, sequence group 7 (SG7), which was geographically widespread in three locations. The drug resistance pattern showed that 14.2%, 20%, and 77% of the A. baumannii isolates were resistant to colistin, tigecycline, and rifampicin, respectively. Nine percent of isolates (8) showed simultaneous resistance to colistin, rifampicin, and tigecycline. Interestingly, all of them were susceptible to ampicillin-sulbactam and/or tobramycin. According to our results, SG7 could be considered as a pan-Iranian clone.

  5. Expanding the Game Design Space

    DEFF Research Database (Denmark)

    Larsen, Lasse Juel; Majgaard, Gunver

    2016-01-01

    This article considers game design research in educational settings. Its focus is on how undergraduate students – particularly engineering students – learn computer game design. From observations conducted during our game design courses we have developed a model of expanded game design space....... It encapsulates the entire development process from the first ideas to the final game with emphasis on game design thinking. Our model of expanded game design space consists of four separate – yet interconnected – layers in the process of game development. The first layer addresses the importance of framing......, providing a clear game design assignment that involves the formulation of intended player experience and a description of game mechanics. The second layer focuses on game design thinking from six different aspects of game design chosen in relation to the framing of the game design assignment. The third...

  6. Helical screw expander evaluation project

    Science.gov (United States)

    McKay, R.

    1982-03-01

    A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  7. Seal-less cryogenic expander

    International Nuclear Information System (INIS)

    Faria, L.E.; Christopher, E.H.

    1987-01-01

    In an expander for use in a split Stirling cycle refrigeration system of the type wherein a displacer moves with reciprocating motion inside an expander housing, and wherein a plunger force and a regenerator force are formed on the displacer, the plunger force cyclically varying and having a time of minimum and maximum plunger force amplitude, and the regenerator force cyclically varying and having a time of minimum and maximum regenerator force amplitude, the improvement is described comprising: (a) means for maintaining displacer forces, such that the maximum plunger force amplitude is substantially equal to the maximum regenerator force amplitude; and (b) means for adjusting a time difference, the time difference being the time between the time of maximum plunger force and the time of maximum regenerator force such that a measure of the cooling power of the refrigeration system is maximized

  8. Eradication of multidrug-resistant A. baumannii in burn wounds by antiseptic pulsed electric field

    Science.gov (United States)

    Golberg, Alexander; Broelsch, G. Felix; Vecchio, Daniela; Khan, Saiqa; Hamblin, Michael R.; Austen, William G.; Sheridan, Robert L.; Yarmush, Martin L.

    2014-01-01

    Emerging bacterial resistance to multiple drugs is an increasing problem in burn wound management. New non-pharmacologic interventions are needed for burn wound disinfection. Here we report on a novel physical method for disinfection: antiseptic pulsed electric field (PEF) applied externally to the infected burns. In a mice model, we show that PEF can reduce the load of multidrug resistant Acinetobacter baumannii present in a full thickness burn wound by more than four orders of magnitude, as detected by bioluminescence imaging. Furthermore, using a finite element numerical model, we demonstrate that PEF provides non-thermal, homogeneous, full thickness treatment for the burn wound, thus, overcoming the limitation of treatment depth for many topical antimicrobials. These modeling tools and our in vivo results will be extremely useful for further translation of the PEF technology to the clinical setting, as they provide the essential elements for planning of electrode design and treatment protocol. PMID:25089285

  9. Clonal spread of blaOXA-72-carrying Acinetobacter baumannii sequence type 512 in Taiwan.

    Science.gov (United States)

    Kuo, Han-Yueh; Hsu, Po-Jui; Chen, Jiann-Yuan; Liao, Po-Cheng; Lu, Chia-Wei; Chen, Chang-Hua; Liou, Ming-Li

    2016-07-01

    This is the first report to show an insidious outbreak of armA- and blaOXA-72-carrying Acinetobacter baumannii sequence type 512 (ST512) at a study hospital in northern Taiwan. Multilocus sequence typing revealed that this was a ST512 clone. All of the isolates with ST512 carried a novel 12,056-bp repGR2 in combination with a repGR12-type plasmid. This plasmid, designated pAB-ML, had one copy of the blaOXA-72 gene that was flanked by XerC/XerD-like sites and conferred resistance to carbapenems. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  10. Tandem Mass Spectrometry Detection of Quorum Sensing Activity in Multidrug Resistant Clinical Isolate Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Kok-Gan Chan

    2014-01-01

    Full Text Available Many Proteobacteria communicate via production followed by response of quorum sensing molecules, namely, N-acyl homoserine lactones (AHLs. These molecules consist of a lactone moiety with N-acyl side chain with various chain lengths and degrees of saturation at C-3 position. AHL-dependent QS is often associated with regulation of diverse bacterial phenotypes including the expression of virulence factors. With the use of biosensor and high resolution liquid chromatography tandem mass spectrometry, the AHL production of clinical isolate A. baumannii 4KT was studied. Production of short chain AHL, namely, N-hexanoyl-homoserine lactone (C6-HSL and N-octanoyl-homoserine lactone (C8-HSL, was detected.

  11. Effects of meropenem exposure in persister cells of Acinetobacter calcoaceticus-baumannii.

    Science.gov (United States)

    Gallo, Stephanie Wagner; Donamore, Bruna Kern; Pagnussatti, Vany Elisa; Ferreira, Carlos Alexandre Sanchez; de Oliveira, Sílvia Dias

    2017-02-01

    To evaluate the influence of meropenem in the Acinetobacter calcoaceticus-baumannii (ACB) persister levels. Persister levels in planktonic and biofilm cultures from ACB isolates were evaluated after exposure to different meropenem concentrations. A high variability of persister fractions was observed among the isolates cultured under planktonic and biofilm conditions. Meropenem concentration did not influence persister fractions, even when far above the MIC. No correlation was found between persister levels and biofilm biomass. The magnitude of persister levels from ACB planktonic and, particularly, biofilm cultures exposed to meropenem was independent of the antibiotic concentration, dosing regimen and biofilm biomass. These findings, in a context of meropenem failure to treat chronic infections, strengthen the importance of understanding persister behavior.

  12. Levels of persisters influenced by aeration in Acinetobacter calcoaceticus-baumannii.

    Science.gov (United States)

    Donamore, Bruna Kern; Gallo, Stephanie Wagner; Abreu Ferreira, Pedro Maria; Sanchez Ferreira, Carlos Alexandre; de Oliveira, Sílvia Dias

    2018-02-01

    To evaluate the influence of aeration on persister levels from Acinetobacter calcoaceticus-baumannii isolates exposed to meropenem or tobramycin, as well as analyze morphological and structural changes in persisters. Levels of persisters were determined after a 48-h exposure to tobramycin or meropenem under aerated or static conditions, and persisters were analyzed by scanning and transmission electron microscopy. The fractions of persisters varied between isolates. Aeration reduced cell survival under each antibiotic treatment, and cell survival decreased as the tobramycin concentration was increased. Interestingly, division septa were observed in persisters by electron microscopy. Aeration may have stimulated bacterial growth, providing more targets for antibiotic action and leading to increased production of reactive oxygen species, which decreased levels of persisters.

  13. Insertions in the OCL1 locus of Acinetobacter baumannii lead to shortened lipooligosaccharides

    Science.gov (United States)

    Kenyon, Johanna J.; Holt, Kathryn E.; Pickard, Derek; Dougan, Gordon; Hall, Ruth M.

    2014-01-01

    Genomes of 82 Acinetobacter baumannii global clones 1 (GC1) and 2 (GC2) isolates were sequenced and different forms of the locus predicted to direct synthesis of the outer core (OC) of the lipooligosaccharide were identified. OCL1 was in all GC2 genomes, whereas GC1 isolates carried OCL1, OCL3 or a new locus, OCL5. Three mutants in which an insertion sequence (ISAba1 or ISAba23) interrupted OCL1 were identified. Isolates with OCL1 intact produced only lipooligosaccharide, while the mutants produced lipooligosaccharide of reduced molecular weight. Thus, the assignment of the OC locus as that responsible for the synthesis of the OC is correct. PMID:24861001

  14. Variantes terapéuticas en la sepsis provocada por gérmenes multirresistentes Therapeutic variants in the sepsis caused by multiresistant germs

    Directory of Open Access Journals (Sweden)

    Moisés Morejón García

    2006-08-01

    Full Text Available La resistencia bacteriana se ha convertido en una problemática actual, primero, por su ascenso constante y segundo, por la aparición cada vez más preocupante, de cepas bacterianas resistente a múltiples antimicrobianos a los que anteriormente eran sensibles. Esto asociado al poco desarrollo de nuevos antimicrobianos pone a los médicos en situación desventajosa ante la sepsis por gérmenes multirresistentes. En este trabajo se exponen una revisión de los gérmenes, tanto grampositivos como gramnegativos, que más están participando en este fenómeno, así como los antimicrobianos con que se dispone actualmente para su enfrentamientoBacterial resistance has become a current problem, first, due to its constant rise and, secondly, to the increasingly worrying appearance of bacterial strains resistant to multiple microorganisms to which they were previously sensitive. This associated with the poor development of antimicrobials, has put doctors in a disadvantageous situation in the case of sepsis due to multiresistant germs. A review of the grampositive and gramnegative germs participating the most in this phenomenon, as well as of the available antimicrobials nowadays to fight them was made in this paper

  15. Whole genome and transcriptome analyses of environmental antibiotic sensitive and multi-resistant Pseudomonas aeruginosa isolates exposed to waste water and tap water.

    Science.gov (United States)

    Schwartz, Thomas; Armant, Olivier; Bretschneider, Nancy; Hahn, Alexander; Kirchen, Silke; Seifert, Martin; Dötsch, Andreas

    2015-01-01

    The fitness of sensitive and resistant Pseudomonas aeruginosa in different aquatic environments depends on genetic capacities and transcriptional regulation. Therefore, an antibiotic-sensitive isolate PA30 and a multi-resistant isolate PA49 originating from waste waters were compared via whole genome and transcriptome Illumina sequencing after exposure to municipal waste water and tap water. A number of different genomic islands (e.g. PAGIs, PAPIs) were identified in the two environmental isolates beside the highly conserved core genome. Exposure to tap water and waste water exhibited similar transcriptional impacts on several gene clusters (antibiotic and metal resistance, genetic mobile elements, efflux pumps) in both environmental P. aeruginosa isolates. The MexCD-OprJ efflux pump was overexpressed in PA49 in response to waste water. The expression of resistance genes, genetic mobile elements in PA49 was independent from the water matrix. Consistently, the antibiotic sensitive strain PA30 did not show any difference in expression of the intrinsic resistance determinants and genetic mobile elements. Thus, the exposure of both isolates to polluted waste water and oligotrophic tap water resulted in similar expression profiles of mentioned genes. However, changes in environmental milieus resulted in rather unspecific transcriptional responses than selected and stimuli-specific gene regulation. © 2014 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  16. Efficacy of Olyset® Plus, a new long-lasting insecticidal net incorporating permethrin and piperonyl-butoxide against multi-resistant malaria vectors [corrected].

    Directory of Open Access Journals (Sweden)

    Cédric Pennetier

    Full Text Available Due to the rapid extension of pyrethroid resistance in malaria vectors worldwide, manufacturers are developing new vector control tools including insecticide mixtures containing at least two active ingredients with different mode of action as part of insecticide resistance management. Olyset® Plus is a new long-lasting insecticidal net (LLIN incorporating permethrin and a synergist, piperonyl butoxide (PBO, into its fibres in order to counteract metabolic-based pyrethroid resistance of mosquitoes. In this study, we evaluated the efficacy of Olyset® Plus both in laboratory and field against susceptible and multi-resistant malaria vectors and compared with Olyset Net, which is a permethrin incorporated into polyethylene net. In laboratory, Olyset® Plus performed better than Olyset® Net against susceptible Anopheles gambiae strain with a 2-day regeneration time owing to an improved permethrin bleeding rate with the new incorporation technology. It also performed better than Olyset® Net against multiple resistant populations of An. gambiae in experimental hut trials in West Africa. Moreover, the present study showed evidence for a benefit of incorporating a synergist, PBO, with a pyrethroid insecticide into mosquito netting. These results need to be further validated in a large-scale field trial to assess the durability and acceptability of this new tool for malaria vector control.

  17. 99mTc(CO)3-Garenoxacin dithiocarbamate synthesis and biological evolution in rats infected with multiresistant Staphylococcus aureus and penicillin-resistant Streptococci

    International Nuclear Information System (INIS)

    Syed Qaiser Shah; Aakif Ullah Khan; Muhammad Rafiullah Khan

    2011-01-01

    99m Tc(CO) 3 -Garenoxacin dithiocarbamate ( 99m Tc(CO) 3 -GXND) complex was synthesized and biologically characterized in rats artificially infected with multiresistant Staphylococcus aureus (MDRSA) and penicillin-resistant Streptococci (PRSC). The characteristics of the 99m Tc(CO) 3 -GXND complex was assessed in terms of radiochemical stability in saline, serum, in vitro binding with live and heat killed MDRSA and PRSC and biodistribution in rats artificially infected with MDRSA and PRSC. The complex showed maximum radiochemical stability at 30 min and remained more than 90% stable up to 240 min in normal saline after reconstitution. The complex was found stable in serum at 37 deg C up to 16 h. The complex showed in vitro saturated binding with living MDRSA and PRSC. In rats infected with living MDRSA and PRSC the complex showed five higher up take in the infected muscle as compared to the inflamed and normal muscle. No significant difference in uptake of the complex in rats infected with heat killed MDRSA and PRSC was observed. The disappearance of the complex from the blood and appearance in the urinary system confirm the normal biological route of biodistribution and excretion. The high values of the radiochemical stability in normal saline, serum, saturated in vitro binding with living MDRSA and PRSC and significant infected to normal muscles ratios, the 99m Tc(CO) 3 -GXND complex is recommended for the localization of soft tissue infection caused by living MDRSA and PRSC. (author)

  18. The battle against multi-resistant strains: Renaissance of antimicrobial essential oils as a promising force to fight hospital-acquired infections.

    Science.gov (United States)

    Warnke, Patrick H; Becker, Stephan T; Podschun, Rainer; Sivananthan, Sureshan; Springer, Ingo N; Russo, Paul A J; Wiltfang, Joerg; Fickenscher, Helmut; Sherry, Eugene

    2009-10-01

    Hospital-acquired infections and antibiotic-resistant bacteria continue to be major health concerns worldwide. Particularly problematic is methicillin-resistant Staphylococcus aureus (MRSA) and its ability to cause severe soft tissue, bone or implant infections. First used by the Australian Aborigines, Tea tree oil and Eucalyptus oil (and several other essential oils) have each demonstrated promising efficacy against several bacteria and have been used clinically against multi-resistant strains. Several common and hospital-acquired bacterial and yeast isolates (6 Staphylococcus strains including MRSA, 4 Streptococcus strains and 3 Candida strains including Candida krusei) were tested for their susceptibility for Eucalyptus, Tea tree, Thyme white, Lavender, Lemon, Lemongrass, Cinnamon, Grapefruit, Clove Bud, Sandalwood, Peppermint, Kunzea and Sage oil with the agar diffusion test. Olive oil, Paraffin oil, Ethanol (70%), Povidone iodine, Chlorhexidine and hydrogen peroxide (H(2)O(2)) served as controls. Large prevailing effective zones of inhibition were observed for Thyme white, Lemon, Lemongrass and Cinnamon oil. The other oils also showed considerable efficacy. Remarkably, almost all tested oils demonstrated efficacy against hospital-acquired isolates and reference strains, whereas Olive and Paraffin oil from the control group produced no inhibition. As proven in vitro, essential oils represent a cheap and effective antiseptic topical treatment option even for antibiotic-resistant strains as MRSA and antimycotic-resistant Candida species.

  19. Antimicrobial resistance in faecal Escherichia coli isolates from farmed red deer and wild small mammals. Detection of a multiresistant E. coli producing extended-spectrum beta-lactamase.

    Science.gov (United States)

    Alonso, C A; González-Barrio, D; Tenorio, Carmen; Ruiz-Fons, F; Torres, C

    2016-04-01

    Eighty-nine Escherichia coli isolates recovered from faeces of red deer and small mammals, cohabiting the same area, were analyzed to determine the prevalence and mechanisms of antimicrobial resistance and molecular typing. Antimicrobial resistance was detected in 6.7% of isolates, with resistances to tetracycline and quinolones being the most common. An E. coli strain carrying blaCTX-M-1 as well as other antibiotic resistant genes included in an unusual class 1 integron (Intl1-dfrA16-blaPSE-1-aadA2-cmlA1-aadA1-qacH-IS440-sul3-orf1-mef(B)Δ-IS26) was isolated from a deer. The blaCTX-M-1 gene was transferred by conjugation and transconjugants also acquired an IncN plasmid. This strain was typed as ST224, which seems to be well adapted to both clinical and environmental settings. The phylogenetic distribution of the 89 strains varied depending on the animal host. This work reveals low antimicrobial resistance levels among faecal E. coli from wild mammals, which reflects a lower selective pressure affecting these bacteria, compared to livestock. However, it is remarkable the detection of a multi-resistant ESBL-E. coli with an integron carrying clinically relevant antibiotic-resistance genes, which can contribute to the dissemination of resistance determinants among different ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Kinetics and Novel Degradation Pathway of Permethrin in Acinetobacter baumannii ZH-14

    Directory of Open Access Journals (Sweden)

    Hui Zhan

    2018-02-01

    Full Text Available Persistent use of permethrin has resulted in its ubiquitous presence as a contaminant in surface streams and soils, yet little is known about the kinetics and metabolic behaviors of this pesticide. In this study, a novel bacterial strain Acinetobacter baumannii ZH-14 utilizing permethrin via partial hydrolysis pathways was isolated from sewage sludge. Response surface methodology based on Box-Behnken design of cultural conditions was used for optimization resulting in 100% degradation of permethrin (50 mg·L−1 within 72 h. Strain ZH-14 degraded permethrin up to a concentration of 800 mg·L−1. Biodegradation kinetics analysis indicated that permethrin degradation by this strain was concentration dependent, with a maximum specific degradation rate, half-saturation constant, and inhibition constant of 0.0454 h−1, 4.7912 mg·L−1, and 367.2165 mg·L−1, respectively. High-performance liquid chromatography and gas chromatography-mass spectrometry identified 3-phenoxybenzenemethanol and 3-phenoxybenzaldehyde as the major intermediate metabolites of the permethrin degradation pathway. Bioaugmentation of permethrin-contaminated soils with strain ZH-14 significantly enhanced degradation, and over 85% of permethrin was degraded within 9 days with the degradation process following the first-order kinetic model. In addition to degradation of permethrin, strain ZH-14 was capable of degrading a large range of synthetic pyrethroids such as deltamethrin, bifenthrin, fenpropathrin, cyhalothrin, and beta-cypermethrin which are also widely used pesticides with environmental contamination problems, suggesting the promising potentials of A. baumannii ZH-14 in bioremediation of pyrethroid-contaminated terrestrial and aquatic environments.

  1. A new trilocus sequence-based multiplex-PCR to detect major Acinetobacter baumannii clones.

    Science.gov (United States)

    Martins, Natacha; Picão, Renata Cristina; Cerqueira-Alves, Morgana; Uehara, Aline; Barbosa, Lívia Carvalho; Riley, Lee W; Moreira, Beatriz Meurer

    2016-08-01

    A collection of 163 Acinetobacter baumannii isolates detected in a large Brazilian hospital, was potentially related with the dissemination of four clonal complexes (CC): 113/79, 103/15, 109/1 and 110/25, defined by University of Oxford/Institut Pasteur multilocus sequence typing (MLST) schemes. The urge of a simple multiplex-PCR scheme to specify these clones has motivated the present study. The established trilocus sequence-based typing (3LST, for ompA, csuE and blaOXA-51-like genes) multiplex-PCR rapidly identifies international clones I (CC109/1), II (CC118/2) and III (CC187/3). Thus, the system detects only one (CC109/1) out of four main CC in Brazil. We aimed to develop an alternative multiplex-PCR scheme to detect these clones, known to be present additionally in Africa, Asia, Europe, USA and South America. MLST, performed in the present study to complement typing our whole collection of isolates, confirmed that all isolates belonged to the same four CC detected previously. When typed by 3LST-based multiplex-PCR, only 12% of the 163 isolates were classified into groups. By comparative sequence analysis of ompA, csuE and blaOXA-51-like genes, a set of eight primers was designed for an alternative multiplex-PCR to distinguish the five CC 113/79, 103/15, 109/1, 110/25 and 118/2. Study isolates and one CC118/2 isolate were blind-tested with the new alternative PCR scheme; all were correctly clustered in groups of the corresponding CC. The new multiplex-PCR, with the advantage of fitting in a single reaction, detects five leading A. baumannii clones and could help preventing the spread in healthcare settings. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii.

    Science.gov (United States)

    Raible, Kevin M; Sen, Bhaswati; Law, Nancy; Bias, Tiffany E; Emery, Christopher L; Ehrlich, Garth D; Joshi, Suresh G

    2017-11-16

    Acinetobacter baumannii is a nosocomial pathogen which is establishing as a major cause of morbidity and mortality within the healthcare community. The success of this pathogen is largely due to its ability to rapidly gain resistance to antimicrobial therapies and its capability to persist in an abiotic environment through the production of a biofilm. Our tertiary-care hospital has showed high incidence of carbapenem-resistant Acinetobacter baumannii (CRAB) isolates. In this study we explore both genotypic and phenotypic properties of 26 CRAB isolates: 16 isolates were collected from January 2010 to March 2011, and 10 were collected between February and May 2015. We determined that all 26 CRAB isolates possessed multiple β-lactamase genes, including genes from Groups A, C, and D. Specifically, 42% of the isolates possesses the potentially plasmid-borne genes of OXA-23-like or OXA-40-like β-lactamase. The presence of mobile gene element integron cassettes and/or integrases in 88% of the isolates suggests a possible mechanism of dissemination of antibiotic resistance genes. Additionally, the location of insertion sequence (IS) ISAba1 in promotor region of of the OXA-51-like, ADC-7, and ampC genes was confirmed. Multilocus sequence typing (MLST) demonstrated that all 26 CRAB isolates were either sequence type (ST)-229 or ST-2. Interestingly, ST-2 went from being the minority CRAB strain in the 2010-2011 isolates to the predominant strain in the 2015 isolates (from 32 to 90%). We show that the ST-2 strains have an enhanced ability to produce biofilms in comparison to the ST-229 strains, and this fact has potentially led to more successful colonization of the clinical environment over time. This study provides a longitudinal genetic and phenotypic survey of two CRAB sequence types, and suggests how their differing phenotypes may interact with the selective pressures of a hospital setting effecting strain dominance over a 5-year period.

  3. Accurate and Rapid Differentiation of Acinetobacter baumannii Strains by Raman Spectroscopy: a Comparative Study.

    Science.gov (United States)

    Ghebremedhin, Meron; Heitkamp, Rae; Yesupriya, Shubha; Clay, Bradford; Crane, Nicole J

    2017-08-01

    In recent years, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has become the standard for routine bacterial species identification