Full Text Available Outbreaks of hospital infections caused by multidrug resistant Acinetobacter baumannii strains are of increasing concern worldwide. Although it has been reported that particular outbreak strains are geographically widespread, little is known about the diversity and phylogenetic relatedness of A. baumannii clonal groups. Sequencing of internal portions of seven housekeeping genes (total 2,976 nt was performed in 154 A. baumannii strains covering the breadth of known diversity and including representatives of previously recognized international clones, and in 19 representatives of other Acinetobacter species. Restricted amounts of diversity and a star-like phylogeny reveal that A. baumannii is a genetically compact species that suffered a severe bottleneck in the recent past, possibly linked to a restricted ecological niche. A. baumannii is neatly demarcated from its closest relative (genomic species 13TU and other Acinetobacter species. Multilocus sequence typing analysis demonstrated that the previously recognized international clones I to III correspond to three clonal complexes, each made of a central, predominant genotype and few single locus variants, a hallmark of recent clonal expansion. Whereas antimicrobial resistance was almost universal among isolates of these and a novel international clone (ST15, isolates of the other genotypes were mostly susceptible. This dichotomy indicates that antimicrobial resistance is a major selective advantage that drives the ongoing rapid clonal expansion of these highly problematic agents of nosocomial infections.
Diancourt, Laure; Passet, Virginie; Nemec, Alexandr; Dijkshoorn, Lenie; Brisse, Sylvain
Outbreaks of hospital infections caused by multidrug resistant Acinetobacter baumannii strains are of increasing concern worldwide. Although it has been reported that particular outbreak strains are geographically widespread, little is known about the diversity and phylogenetic relatedness of A. baumannii clonal groups. Sequencing of internal portions of seven housekeeping genes (total 2,976 nt) was performed in 154 A. baumannii strains covering the breadth of known diversity and including representatives of previously recognized international clones, and in 19 representatives of other Acinetobacter species. Restricted amounts of diversity and a star-like phylogeny reveal that A. baumannii is a genetically compact species that suffered a severe bottleneck in the recent past, possibly linked to a restricted ecological niche. A. baumannii is neatly demarcated from its closest relative (genomic species 13TU) and other Acinetobacter species. Multilocus sequence typing analysis demonstrated that the previously recognized international clones I to III correspond to three clonal complexes, each made of a central, predominant genotype and few single locus variants, a hallmark of recent clonal expansion. Whereas antimicrobial resistance was almost universal among isolates of these and a novel international clone (ST15), isolates of the other genotypes were mostly susceptible. This dichotomy indicates that antimicrobial resistance is a major selective advantage that drives the ongoing rapid clonal expansion of these highly problematic agents of nosocomial infections. PMID:20383326
Saugar, José María; Alarcón, Teresa; López-Hernández, Susana; López-Brea, Manuel; Andreu, David; Rivas, Luis
Polymyxin B (PXB) and the cecropin A-melittin hybrid CA(1-8)M(1-18) (KWKLFKKIGIGAVLKVLTTGLPALIS-NH2) were compared for antibiotic activity on reference and multiresistant Acinetobacter baumannii strains. Significant differences for both peptides were observed on their inner membrane interaction and inhibition by environmental factors, supporting the use of CA(1-8)M(1-18) as a potential alternative to PXB against Acinetobacter.
Marti, Sara; Sánchez-Céspedes, Javier; Espinal, Paula; Vila, Jordi
Abstract Acinetobacter baumannii is a multiresistant opportunistic nosocomial pathogen responsible for outbreaks worldwide. The main infection caused by this microorganism is nosocomial pneumonia, in particular ventilator-associated pneumonia in patients in Intensive Care Units. Treatment of these nosocomial infections is becoming problematic because the level of resistance to antimicrobial agents is rising. Ceftobiprole is a new cephalosporin with activity against Gram-positive an...
Rumbo, C.; Gato, E.; López, M.; Ruiz de Alegría, C.; Fernández-Cuenca, F.; Martínez-Martínez, L.; Vila, J.; Pachón, J.; J. M. Cisneros; Rodríguez-Baño, Jesús; A. Pascual; Bou,G.; Tomás, M.
Weinvestigated 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 PFGEROC- 1 (53 strains producing the OXA-58B-lactamase enzyme and 18 strains with the OXA-24B-lactamase) and clone PFGE-HUI-1 (19 strains susceptible to carbapenems).Weused real-time reverse transcriptase PCR to correlate antimicrobi...
Full Text Available Acinetobacter baumannii is an important opportunistic pathogen associated with a variety of nosocomial infections. A rapid and sensitive molecular detection in clinical isolates is quite needed for the appropriate therapy and outbreak control of A. baumannii. Group 2 carbapenems have been considered the agents of choice for the treatment of multiple drug resistant A. baumannii. But the prevalence of carbapenem-resistant A. baumannii (CRAB has been steadily increasing in recent years. Here, we developed a loop-mediated isothermal amplification (LAMP assay for the rapid detection of A. baumannii in clinical samples by using high-specificity primers of the blaOXA-51 gene. Then we investigated the OXA-carbapenemases molecular epidemiology of A. baumannii isolates in 2 comprehensive hospitals in Beijing. The results showed that the LAMP assay could detect target DNA within 60 min at 65°C. The detection limit was 50 pg/μl, which was about 10-fold greater than that of PCR. Furthermore, this method could distinguish A. baumannii from the homologous A. nosocomialis and A. pittii. A total of 228 positive isolates were identified by this LAMP-based method for A. baumannii from 335 ICU patients with clinically suspected multi-resistant infections in 2 hospitals in Beijing. The rates of CRAB are on the rise and are slowly becoming a routine phenotype for A. baumannii. Among the CRABs, 92.3% harbored both the blaOXA-23 and blaOXA-51 genes. Thirty-three pulsotypes were identified by pulsed-field gel electrophoresis, and the majority belonged to clone C. In conclusion, the LAMP method developed for detecting A. baumannii was faster and simpler than conventional PCR and has great potential for both point-of-care testing and basic research. We further demonstrated a high distribution of class D carbapenemase-encoding genes, mainly OXA-23, which presents an emerging threat in hospitals in China.
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
M. S. Ramírez; Bello, H.; G. González Rocha; C. Márquez; Centrón, D.
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 a...
Gao, Jianping; Zou, Yingchang; Wang, Yonggang; Wang, Feng; Lang, Lang; Wang, Ping; Zhou, Yong; Ying, Kejing
A number of multiresistant pathogens including Acinetobacter baumannii (A. baumannii) place a heavy burden on ventilator-associated pneumonia (VAP) patients in intensive care units (ICU). It is critically important to differentiate between bacterial infection and colonization to avoid prescribing unnecessary antibiotics. Quantitative culture of lower respiratory tract (LRT) specimens, however, requires invasive procedures. Nowadays, volatile organic compounds (VOCs) have been studied in vitro and in vivo to identify pathogen-derived biomarkers. Therefore, an exploratory pilot study was conceived for a proof of concept that the appearance and level of A. baumannii-derived metabolites might be correlated with the presence of the pathogen and its ecological niche (i.e. the infection and colonization states) in ICU ventilated patients. Twenty patients with A. baumannii VAP (infection group), 20 ventilated patients with LRT A. baumannii colonization (colonization group) and 20 ventilated patients with neurological disorders, but without pneumonia or A. baumannii colonization (control group) were enrolled in the in vivo pilot study. A clinical isolate of A. baumannii strains was used for the in vitro culture experiment. The adsorptive preconcentration (solid-phase microextraction fiber and Tenax(®) TA) and analysis technique of gas chromatography-mass spectrometry were applied in the studies. Breath profiles could be visually differentiated between A. baumannii cultivation in vitro and culture medium, and among in vivo groups. In the in vitro experiment, nine compounds of interest (2,5-dimethyl-pyrazine, 1-undecene, isopentyl 3-methylbutanoate, decanal, 1,3-naphthalenediol, longifolene, tetradecane, iminodibenzyl and 3-methyl-indene) in the headspace were found to be possible A. baumannii derivations. While there were eight target VOCs (1-undecene, nonanal, decanal, 2,6,10-trimethyl-dodecane, 5-methyl-5-propyl-nonane, longifolene, tetradecane and 2-butyl-1-octanol
Cirioni, Oscar; Simonetti, Oriana; Pierpaoli, Elisa; Barucca, Alessandra; Ghiselli, Roberto; Orlando, Fiorenza; Pelloni, Maria; Minardi, Daniele; Trombettoni, Maria Michela Cappelletti; Guerrieri, Mario; Offidani, Annamaria; Giacometti, Andrea; Provinciali, Mauro
We investigated the efficacy of colistin combined with pexiganan in experimental mouse models of Acinetobacter baumannii infection.Adult male BALB/c mice received intraperitoneally 1 mL saline containing 2 × 10 CFU of susceptible and multiresistant A. baumannii. Two hours after bacterial challenge, animals received 1 mg/kg of colistin, 1 mg/kg of pexiganan, or 1 mg/kg of colistin plus 1 mg/kg of pexiganan.Blood culture positivity, the quantities of bacteria in the intra-abdominal fluid, the rate of lethality and immunological studies, such as immunophenotyping and NK cytotoxicity, were evaluated.In the in vitro study, A. baumannii showed susceptibility to colistin and pexiganan and a strong synergy was observed by testing colistin combined with pexiganan with fractionary inhibitory concentration index of 0.312 for both strains.In the in vivo study colistin or pexiganan alone showed a good antimicrobial efficacy. When colistin was combined with pexiganan, the positive interaction produced low bacterial counts that were statistically significant versus singly treated groups. For both strains the highest rate of survival was observed in combined-treated groups (90%).Pexiganan increased NK cytotoxic activity over the levels of infected and colistin-treated animals.In conclusion, pexiganan combined with colistin was found to be efficacious against A. baumannii infection. PMID:26849630
Iacono, M.; Villa, L.; Fortini, D.; Bordoni, R.; Imperi, F.; Bonnal, R.J.P.; Sicheritz-Pontén, Thomas; De Bellis, G.; Visca, P.; Cassone, A.; Carattoli, A.
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...... of A. baumannii ATCC 17978 and Acinetobacter baylyi ADP1, with the aim of identifying novel genes related to virulence and drug resistance. A. baumannii ACICU has a single chromosome of 3,904,116 bp (which is predicted to contain 3,758 genes) and two plasmids, pACICUI and pACICU2, of 28,279 and 64...... than in ATCC 17978 and ADP1 (76.2, 57.2, and 62.5 transporters per Mb of genome, respectively). An antibiotic resistance island, AbaR2, was identified in ACICU and had plausibly evolved by reductive evolution from the AbaR1 island previously described in multiresistant strain A. baumannii AYE. Moreover...
Deuseli Quaresma de Figueiredo
Full Text Available Carbapenemase production is an important mechanism of carbapenem resistance among nonfermentative Gram-negative isolates. This study aimed to report the detection of blaOXA-58 gene in multiresistant clinical isolates of Acinetobacter baumannii recovered from inpatients in a public hospital. Polymerase chain reaction tests were performed to detect the blaOXA-23-like, blaOXA-24-like, blaOXA-58-like and blaOXA-51-like genes. The blaOXA-58 and blaOXA-23 genes were detected in one and three isolates, respectively. Sequencing of the blaOXA-58-like amplicon revealed 100% identity with the A. baumannii blaOXA-58 gene listed in the GenBank database. This is the first report of an OXA-58-producing A. baumannii isolate in Rio de Janeiro, Brazil.
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.
Alessandra Einsfeld Ferreira
Full Text Available INTRODUCTION: Hospitals around the world have presented multiresistant Acinetobacter sp. outbreaks. The spread of these isolates that harbor an increasing variety of resistance genes makes the treatment of these infections and their control within the hospital environment more difficult. This study aimed to evaluate the occurrence and dissemination of Acinetobacter sp. multiresistant isolates and to identify acquired resistance genes. METHODS: We analyzed 274 clinical isolates of Acinetobacter sp. from five hospitals in Porto Alegre, RS, Brazil. We evaluated the susceptibility to antimicrobial, acquired resistance genes from Ambler's classes B and D, and performed molecular typing of the isolates using enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR technique. RESULTS: A high (68% percentage of multiresistant isolates of Acinetobacter sp. was observed, and 69% were resistant to carbapenems. We identified 84% of isolates belonging to species A. baumannii because they presented the gene blaOXA-51. The gene blaOXA-23 was detected in 62% of the isolates, and among these, 98% were resistant to carbapenems. Using the ERIC-PCR technique, we identified clones of Acinetobacter sp. spread among the four hospitals analyzed during the sampling period. CONCLUSIONS: The data indicate the dissemination of Acinetobacter sp. isolates among hospitals and their permanence in the hospital after one year.
Nosocomial outbreaks due to Pseudomonas aeruginosa and Acinetobacter baumannii in a Neonatal Intensive Care Unit (NICU of the Uberlândia Federal University Hospital Surto hospitalar por Pseudomonas aeruginosa e Acinetobacter baumannii em uma Unidade de Terapia Intensiva Neonatal (UTIN do Hospital de Clínicas da Universidade Federal de Uberlândia (HC-UFU
Denise Von Dolinger de Brito
Full Text Available The study documents the occurrence of two subsequent outbreaks in the NICU of HC-UFU, caused by epidemic strains of multiresistant Pseudomonas aeruginosa and Acinetobacter baumannii, that occurred between March/01 and September and between October/01 and March/02, respectively. The P. aeruginosa outbreak included seven neonates with conjunctivitis and three with bacteremia. A case-control study was conducted for the A. baumannii outbreak, with 11 and 22 neonates, respectively. The isolates of A. baumannii were resistant to gentamacin and ciprofloxacin. P. aeruginosa isolates were resistant to ampicillin/sulbactam gentamicin and ciprofloxacin. The hands of healthcare workers and environmental cultures were negative. The outbreak of P. aeruginosa resulted in the increase of use of imipenem, which could have favoured the emergence of a A. baumannii epidemic strain, despite of its susceptibility to this antibiotic. The risk factors for A. baumannii infection were: weight 7 days and use of carbapenems. Containment of the two outbreaks was achieved by introduction of strict hygiene measures and careful nursing care of the infected infants. The reservatory and the route of transmission were not found.O objetivo foi relatar a ocorrência de dois surtos subseqüentes na UTIN do HC-UFU, por amostras epidêmicas de P. aeruginosa e A. baumannii multirresistentes nos períodos de Mar - Set/01 e Out - Mar/02, respectivamente. O surto por P. aeruginosa incluiu sete neonatos com conjuntivite e três com bacteremia e um estudo caso-controle foi realizado no surto por A. baumannii com 11 e 22 neonatos respectivamente. Os isolados de A. baumannii foram resistentes a gentamicina e ciprofloxacina e os de P. aeruginosa a ampicilina/sulbactam além de gentamicina e ciprofloxacina. As culturas ambientais e das mãos dos profissionais de saúde foram negativas. O surto por P. aeruginosa resultou no aumento do uso de imipenem o que pode ter favorecido a emergência do
Pasanen, Tanja; Koskela, Suvi; Mero, Sointu; Tarkka, Eveliina; Tissari, Päivi; Vaara, Martti; Kirveskari, Juha
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. PMID:24465749
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.
Silveira, Maria José da Costa Pinho
A espécie Acinetobacter baumannii é um microrganismo multirresistente, frequentemente associado a surtos e infecções nos cuidados de saúde. A presença de uma grande variedade de factores determinantes na resistência aos antibióticos, juntamente com a sua capacidade de regular esses mecanismos e se adaptar sob condições ambientais adversas, faz com que esta espécie seja centro de preocupação para a Saúde pública. A sua disseminação na maior parte das vezes clonal, dentro das ...
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
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. PMID:23939894
Al Atrouni, Ahmad; Joly-Guillou, Marie-Laure; Hamze, Monzer; Kempf, Marie
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
Al Atrouni, Ahmad; Joly-Guillou, Marie-Laure; Hamze, Monzer; Kempf, Marie
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....
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 vast majority of multidrug resistant (MDR) clinical isolates of A. baumannii from CR belong to clonal lineages termed EU clone I and II; (ii) these two clones have predominated among MDR hospital ...
Valentina Gentile; Emanuela Frangipani; Carlo Bonchi; Fabrizia Minandri; Federica Runci; Paolo Visca
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, w...
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.
Jian LI; Rayner, Craig R; Nation, Roger L; Owen, Roxanne J.; Spelman, Denis; Tan, Kar Eng; Liolios, Lisa
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...
Jong Suk Jin
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.
Rapisarda, Francesco; Aliotta, Roberta; Pocorobba, Barbara; Portale, Grazia; Ferrario, Silvia; Zanoli, Luca; Fatuzzo, Pasquale
Fungal infections have a high incidence in patients receiving peritoneal dialysis. (1) Peritoneal dialysis is often complicated by peritonitis which has only minimally mycotic etiology, but nonetheless it is associated with 15-45% mortality (8). The opportunistic pathogens such as Candida can cause infection in immunocompromised conditions. Even the Acinetobacter tends to infect immunocompromised individuals and it has the same risk factors for infection as Candida: immunosuppression, malignancy, HIV positivity and all the other conditions of immunosuppression, central venous catheterization, mechanical ventilation and prolonged antibiotic therapy. The sepsis by Acinetobacter predicts a negative prognosis with the mortality rate between 20 to 60% (12), especially in cases of isolation of multi-resistant germs. We present a case report of a CKD patient undergoing peritoneal dialysis therapy who was hospitalized for acute pancreatitis, later complicated by the development of pancreatic pseudocysts, C. albicans peritonitis with hematologic spread of the fungus, superimposed Acinetobacter baumannii sepsis and pneumonia. She has been subjected to percutaneous drainage of pseudocysts, to switch from peritoneal dialysis to hemodialysis, to various evacuative thoracentesis, and to polymicrobial therapy (meropenem, teicoplanina, tigeciclina, linezolid, colimicina, fluconazolo, etc.) that allowed the resolution of sepsis. The peculiarity of this case is represented by the numerous morbidity that the patient developed simultaneously, with the genesis of a complex clinical picture, by the combination of infections due to Candida albicans and Acinetobacter baumannii. Successful treatment strategies allowed to fight and cure a medical condition associated with a high mortality rate. PMID:26845211
Hanoch S. I. Martins
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.
Rogers, Benjamin A; Aminzadeh, Zohreh; Hayashi, Yoshiro; Paterson, David L
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. PMID:21653302
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
Aim: Acinetobacter baumannii is an opportunistic nosocomial pathogen and one of the most important multidrug-resistant microorganisms in hospitals worldwide. A.baumannii most commonly causes ventilator-associated pneumonia and blood stream infections and mortality rates in these infections can reach 35%. In this study, it was aimed to assess the frequency of Acinetobacter baumannii species which were considered to be causative agents of nosocomial infection and their resistance to antimicrobi...
Uhde, Ann-Kathrin; Kilwinski, Jochen; Peters, Martin; Verspohl, Jutta; Feßler, Andrea T; Schwarz, Stefan; Wohlsein, Peter
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. PMID:26790938
Arjen F. Nikkels
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.
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.
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
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)
Tarek A. Ahmad
Full Text Available Acinetobacter baumannii has recently crossed all lines once considered harmless, pushing its way as a nosocomial pathogen. It had acquired resistance to almost all available chemotherapies and mainly targets intensive care residents; causing pneumonia and major outbreaks with high mortality rates. This urged the need for preventive methods, which include infection control, non-specific immune-therapy, passive, and active immunization in order to offer vulnerable immune-compromised patients a flare in the dark. Several attempts were done for constructing effective vaccines with promising results. These are precisely classified, documented, and discussed in this up-to-date review.
Full Text Available Multi-resistant pathogens are a serious problem on a considerable scale for the health sector. Patients with infections induced by multi-resistant bacteria cause enormous additional treatment costs of around 20,500 € per insured. Due to the recently used billing and documentation system there is a significant shortage of information transparency. The guidelines for hospital hygiene and infection prevention published by the Robert Koch Institute (RKI include a presumption provision, which means that subject to compliance with these guidelines the observance of the current state of medical science is suspected. In case of a derogation, a scientific justification is necessary, which is used e.g. in connection with liability questions. Within the framework of legal reforms in 2011, the legislator aspires a nationwide improvement of hygiene quality in medical institutions and information transparency. Many specific issues about the general reporting obligation of infections with multi-resistant pathogens or about the standardized exchange of infection documentations between medical institution and health authority remain unresolved. Regional, cross-sectoral networks create the base to tackle targeted measures collectively and may develop sustainable and tailored solutions for their region. With these considerations in mind, the project HICARE was founded in Mecklenburg-Vorpommern. The project pursues the aim to develop an intervention strategy against the spread of multi-resistant pathogens. Health insurances make an important contribution to quality of medical treatment by participation.
Sandvang, Dorthe; Aarestrup, Frank Møller; Jensen, Lars Bogø
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...
Sandvang, Dorthe; Aarestrup, Frank Møller; Jensen, Lars Bogø
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...
Bowers, Dana R.; Cao, Henry; Zhou, Jian; Ledesma, Kimberly R.; Sun, Dongxu; Lomovskaya, Olga; Tam, Vincent H.
Antimicrobial resistance among Acinetobacter baumannii is increasing worldwide, often necessitating combination therapy. The clinical utility of using minocycline with polymyxin B is not well established. In this study, we investigated the activity of minocycline and polymyxin B against 1 laboratory isolate and 3 clinical isolates of A. baumannii. Minocycline susceptibility testing was performed with and without an efflux pump inhibitor, phenylalanine-arginine β-naphthylamide (PAβN). The intr...
Full Text Available BACKGROUND: Despite increasingly frequent bacterial resistance to antibiotics, antibacterial innovation is rare. Ketolides constitute one of the very few new antibiotic classes active against Streptococcus pneumoniae developed during the last 25 years. Their mechanism of action resembles that of macrolides, but they are unaffected by common resistance mechanisms. However, cross-resistance to ketolides has been observed in some macrolide-resistant strains. We examined how new antibiotic exposure may affect overall pneumococcal resistance patterns in the population. The aims of this study were to assess the potential dissemination of newly emerged resistances and to control the selection of strains already multiresistant to existing antimicrobials. METHODOLOGY/PRINCIPAL FINDINGS: We developed an age-structured population model for S. pneumoniae transmission in a human community exposed to heptavalent vaccine, and beta-lactams, macrolides and ketolides. The dynamics of intra-individual selection of resistant strains under antibiotic exposure and interindividual transmission were simulated, with antibiotic-specific resistance mechanisms defining the path to co-resistances and cross-resistances, and parameters concerning the French situation. Results of this simulation study suggest that new antibiotic consumption could markedly slow the diffusion of multiresistant strains. Wider use was associated with slower progression of multiresistance. When ketolides were prescribed to all ages, resistance to them reached 10% after >15 years, while it took >40 years when they were prescribed only to adults. In the scenario according to which new antibiotics totally replaced former antimicrobials, the beta-lactam resistance rate was limited at 70%. CONCLUSIONS: In a context of widespread vaccination and rational use of antibiotics, innovative antibiotic, prescribed to all age groups, may have an added impact on multiresistant-strain dissemination in the
Lawson, Andrew J.; Stanley, John; Threlfall, E. John; Desai, Meeta
Fluorescent amplified fragment length polymorphism (FAFLP) subtyping analysis was used to genotype multiresistant Salmonella enterica serovar Typhimurium definitive phage type 104. Thirteen distinct FAFLP profiles were found among 85 isolates exhibiting identical pulsed-field gel electrophoresis (PFGE) profiles. A single FAFLP profile was shared by 93% of outbreak-associated isolates and 82% of sporadic isolates. This study demonstrates the value of FAFLP as a high-resolution tool for epidemi...
Hu, Yuan; He, Lihua; Tao, Xiaoxia; Meng, Fanliang; Zhang, Jianzhong
Biofilm is recognized as a contributing factor to the capacity of Acinetobacter baumannii to persist and prosper in medical settings, but it is still unknown whether biofilms contribute to the spread of A. baumannii. In this study, the biofilm formation of 114 clinical A. baumannii isolates and 32 non-baumannii Acinetobacter isolates was investigated using a microtiter plate assay. The clonal relationships among A. baumannii isolates were assessed using pulsed-field gel electrophoresis and multilocus sequence typing, and one major outbreak clone and 5 other epidemic clones were identified. Compared with the epidemic or outbreak A. baumannii isolates, the sporadic isolates had significantly higher biofilm formation, but no significant difference was observed between the sporadic A. baumannii isolates and the non-baumannii Acinetobacter isolates, suggesting that biofilm is not important for the epidemic spread of A. baumannii. Of the multidrug-resistant (MDR) A. baumannii isolates in this study, 95.7% were assigned to international clone 2 (IC2) and showed significantly lower biofilm formations than the other isolates, suggesting that biofilm did not contribute to the high success of IC2. These findings have increased our understanding of the potential relationship between biofilm formation and the epidemic capacity of A. baumannii. PMID:27558010
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
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
Lundgaard Andersen, Linda; Soldz, Stephen
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 understa...
Montagu, Angélique; Joly-Guillou, Marie-Laure; Rossines, Elisabeth; Cayon, Jérome; Kempf, Marie; Saulnier, Patrick
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 in response to environmental stress conditions, such as carvacrol. PMID:27486453
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.
Preface; Part I. The de Sitter Universe: 1. Synthetic construction; 2. The reduced model: geodesics; 3. The elliptic interpretation; 4. The static frame; 5. The determination of parallaxes; 6. The Lemaître-Robertson frame; Part II. The Theory of Geodesics: 7. On null geodesics; i. Determination of the parameter for null lines in special cases; ii. Frequency shift; 8. Free particles and light rays in general expanding spaces, flat or hyperspherical; i. Flat spaces; ii. Spherical spaces; iii. The red shift for spherical spaces; Part III. Waves in General Riemannian Space-Time: 9. The nature of our approximation; 10. The Hamilton-Jacobi theory in a gravitational field; 11. Procuring approximate solutions of the Hamilton-Jacobi equation from wave theory; Part IV. Waves in an Expanding Universe: 12. General considerations; 13. Proper vibrations and wave parcels; Bibliography.
Panáček, Aleš; Smékalová, Monika; Večeřová, Renata; Bogdanová, Kateřina; Röderová, Magdaléna; Kolář, Milan; Kilianová, Martina; Hradilová, Šárka; Froning, Jens P; Havrdová, Markéta; Prucek, Robert; Zbořil, Radek; Kvítek, Libor
Bacterial resistance to conventional antibiotics is currently one of the most important healthcare issues, and has serious negative impacts on medical practice. This study presents a potential solution to this problem, using the strong synergistic effects of antibiotics combined with silver nanoparticles (NPs). Silver NPs inhibit bacterial growth via a multilevel mode of antibacterial action at concentrations ranging from a few ppm to tens of ppm. Silver NPs strongly enhanced antibacterial activity against multiresistant, β-lactamase and carbapenemase-producing Enterobacteriaceae when combined with the following antibiotics: cefotaxime, ceftazidime, meropenem, ciprofloxacin and gentamicin. All the antibiotics, when combined with silver NPs, showed enhanced antibacterial activity at concentrations far below the minimum inhibitory concentrations (tenths to hundredths of one ppm) of individual antibiotics and silver NPs. The enhanced activity of antibiotics combined with silver NPs, especially meropenem, was weaker against non-resistant bacteria than against resistant bacteria. The double disk synergy test showed that bacteria produced no β-lactamase when treated with antibiotics combined with silver NPs. Low silver concentrations were required for effective enhancement of antibacterial activity against multiresistant bacteria. These low silver concentrations showed no cytotoxic effect towards mammalian cells, an important feature for potential medical applications. PMID:26970828
Yoko Miyasaki; John D Rabenstein; Joshua Rhea; Marie-Laure Crouch; Mocek, Ulla M.; Patricia Emmett Kittell; Morgan, Margie A.; Wesley Stephen Nichols; M M Van Benschoten; William David Hardy; Liu, George Y
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 antimicrob...
Bahareh Vakili; Hossein Fazeli; Parisa Shoaei; Majid Yaran; Behrooz Ataei; Farzin Khorvash; Moj Khaleghi
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....
Huang, Weiwei; Yao, Yufeng; Long, Qiong; Yang, Xu; Sun, Wenjia; Liu, Cunbao; Jin, Xiaomei; LI Yang; Chu, Xiaojie; Chen, Bin; Ma, Yanbing
Objective Acinetobacter baumannii is considered the prototypical example of a multi- or pan- drug-resistant bacterium. It has been increasingly implicated as a major cause of nosocomial and community-associated infections. This study proposed to evaluate the efficacy of immunological approaches to prevent and treat A. baumannii infections. Methods Mice were immunized with outer membrane vesicles (OMVs) prepared from a clinically isolated multidrug-resistant strain of A. baumannii. Pneumonia a...
Gavinsky, Dmitry; Pudlák, Pavel
Dagstuhl: Schloss Dagstuhl, Leibniz-Zentrum für Informatik, 2014 - (Mayr, E.; Portier, N.), s. 325-336. (Leibniz International Proceedings in Informatics. 25). ISBN 978-3-939897-65-1. ISSN 1868-8969. [International Symposium on Theoretical Aspects of Computer Science (STACS 2014), /31./. Lyon (FR), 05.03.2014-08.03.2014] R&D Projects: GA ČR GBP202/12/G061 Institutional support: RVO:67985840 Keywords : partitions * expanders * random graphs Subject RIV: BA - General Mathematics http://drops.dagstuhl.de/opus/volltexte/2014/4468/
Tan, Xiaojiang; Zhu, Song; Yan, Dongxing; Chen, Weiping; Chen, Ruilan; Zou, Jian; Yan, Jingdong; Zhang, Xiangdong; Farmakiotis, Dimitrios; Mylonakis, Eleftherios
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%, Pmechanical ventilation for at least 48 hours. Candida spp. airway colonization was an independent risk factor for subsequent A. baumannii VAP. PMID:27001670
Shi, Z Y; Liu, P Y; Lau, Y; Lin, Y; Hu, B S; Shir J-M
The in-vitro activity of 18 antimicrobial agents alone or in combination against 248 clinical isolates of Acinetobacter baumannii from Taiwan were tested by agar dilution. The MIC90S of ampicillin, amoxicillin, piperacillin, cefuroxime, cefotaxime, ceftriaxone, gentamicin, and amikacin were at least 128 mu g/ml. Ceftazidime, cefepime, sulbactam, clavulanic acid, and tazobactam presented moderate activity with MIC90S of 32, 16, 16, 32, and 32 mu g/ml, respectively. The increased activity of ampicillin/sulbactam, amoxicillin/clavulanic acid, and piperacillin/tazobactam was due to the intrinsic effect of sulbactam, clavulanic acid, and tazobactam, respectively. Imipenem, meropenem, and ciprofloxacin were the most active antimicrobial agents with MIC90S of 1, 1, and 0.5 mu g/ml, respectively. Nineteen isolates (7.7%) were resistant to all aminoglycosides and beta-lactam antibiotics, except carbapenems and ciprofloxacin. We are concerned about the multidrug resistance of A. baumannii in this study. PMID:9147913
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.
Kuah, B G; Kumarasinghe, G; Doran, J.; Chang, H R
The in vitro activities of 17 antimicrobial agents alone or in combination against 70 clinical isolates of Acinetobacter baumannii from Singapore were determined by broth microdilution. The MICs of amoxicillin, ampicillin, ceftazidime, ceftriaxone, gentamicin, and piperacillin for 90% of the strains were > or = 128 micrograms/ml. Addition of sulbactam to ampicillin produced improved activity, whereas adding tazobactam to piperacillin did not. The MICs of amikacin, ciprofloxacin, and imipenem ...
Multi drug resistant (MDR) strains of Acinetobacter baumannii have emerged as a major cause of nosocomial infections associated with significant morbidity and mortality. Over the last 20 years a worldwide expansion in Acinetobacter infections has been observed associated with intensive care units (ICUs), long term care facilities and wounded armed forces personnel. The developing resistance patterns seen in Acinetobacter sp suggest that the number of effective antibiotics may shortly be exhau...
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.
Margit Gabriele Muller
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.
Full Text Available Fei Gao,1 Qifa Ye,2,3 Qiquan Wan,2 Shan Liu,4 Jiandang Zhou51Infectious Disease Department of Henan Province People’s Hospital, Zhengzhou, 2Department of Transplant Surgery, Third Xiangya Hospital, Central South University, Changsha, 3Department of Transplant Surgery, Zhongnan Hospital, Wuhan University, Wuhan, People’s Republic of China; 4Adelphi University College of Nursing and Public Health, New York, NY, USA; 5Department of Clinical Laboratory of Microbiology, Third Xiangya Hospital, Central South University, Changsha, People’s Republic of ChinaBackground: Drug-resistant Acinetobacter baumannii has become a major problem in liver transplant recipients. The aim of this study was to investigate the clinical presentation, distribution, and drug susceptibility characteristics in liver recipients with A. baumannii infection.Methods: We retrospectively investigated 17 liver recipients who developed A. baumannii infection between January 1, 2007 and December 31, 2014. The distribution of A. baumannii and drug susceptibility characteristics were reviewed.Results: Infectious complications due to A. baumannii appeared in 17 liver recipients, with a total of 24 episodes. Approximately 63% (15/24 of A. baumannii infections occurred within 2 weeks after transplantation. The most common source of infection was multiple culture-positive sites (35.3%, n=6, followed by the intra-abdominal/biliary tract (23.5%, n=4 and lung (23.5%, n=4. Eight patients (47.1% had a body temperature of 38°C or higher at the onset of A. baumannii infection. Nine, seven, and 12 recipients had a serum creatinine level of >1.5 mg/dL, a white blood cell count of >15,000/mm3, and a platelet count of <50,000/mm3, respectively. There were five (29.4% cases of septic shock and eight (47.1% deaths. The rate of antibiotic resistance of A. baumannii to ten of 12 antibiotics investigated was more than 60%. Among the 24 infections caused by A. baumannii, 75% were carbapenem
Schmiedel, Judith; Falgenhauer, Linda; Domann, Eugen; Bauerfeind, Rolf; Prenger-Berninghoff, Ellen; Imirzalioglu, Can; Chakraborty, Trinad
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 ...
Schmiedel, Judith; Falgenhauer, Linda; Domann, Eugen; Bauerfeind, Rolf; Prenger-Berninghoff, Ellen; Imirzalioglu, Can; Chakraborty, Trinad
BACKGROUND:Multiresistant Gram-negative bacteria producing extended-spectrum beta-lactamases (ESBLs) are an emerging problem in human and veterinary medicine. This study focused on comparative molecular characterization of beta-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 iso...
Markou, Nikolaos; Apostolakos, Haralampos; Koumoudiou, Christiana; Athanasiou, Maria; Koutsoukou, Alexandra; Alamanos, Ioannis; Gregorakos, Leonidas
Introduction The increasing prevalence of multiresistant Gram-negative strains in intensive care units (ICUs) has recently rekindled interest in colistin, a bactericidal antibiotic that was used in the 1960s for treatment of infections caused by Gram-negative bacilli. We conducted the present observational study to evaluate the efficacy of intravenous colistin in the treatment of critically ill patients with sepsis caused by Gram-negative bacilli resistant to all other antibiotics. Patients a...
Miyasaki, Yoko; Rabenstein, John D; Rhea, Joshua; Crouch, Marie-Laure; Mocek, Ulla M; Kittell, Patricia Emmett; Morgan, Margie A; Nichols, Wesley Stephen; Van Benschoten, M M; Hardy, William David; Liu, George Y
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. PMID:23630600
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.
Full Text Available Aim: Acinetobacter baumannii is an opportunistic nosocomial pathogen and one of the most important multidrug-resistant microorganisms in hospitals worldwide. A.baumannii most commonly causes ventilator-associated pneumonia and blood stream infections and mortality rates in these infections can reach 35%. In this study, it was aimed to assess the frequency of Acinetobacter baumannii species which were considered to be causative agents of nosocomial infection and their resistance to antimicrobial agents between January 2009 and November 2014 in our hospital. Material and Method: The diagnosis of nosocomial A.baumannii infection was made according to Centers for Disease Control and Prevention (CDC criteria. Identification of the microorganisms isolated from the specimens of the patients and antimicrobial susceptibility testing of them were performed by using VITEK 2 ID-AST automated system. Susceptibilities of amikacin, ampicillin-sulbactam, gentamicin, tobramycin, netilmycin, imipenem, meropenem, piperacillin, piperacillin-tazobactam, ceftazidime, ceftriaxone, cefotaxime, ciprofloxacin, levofloxacin, tetracycline, tigecycline, colistin and co-trimoxazole were investigated in the species. SPSS 19,0 program was used for statistical analysis. Results: A total of 308 Acinetobacter species were isolated and these species were obtained more frequently from the clinical samples sent from the intensive care unit (92,9% and deep tracheal aspirate samples (64,6%. When all of the species were evaluated, the most efficient antibiotics were determined to be colistin, tigecycline and netilmycin. The susceptibility rates for colistin, tigecycline and netilmycin were determined to be 92,8%, 85,3% and 82%, respectively. These are followed by tobramycin with a susceptibility rate of 76,4%, gentamicin with a susceptibility rate of 47,8% and amikacin with a susceptibility rate of 46,3%. Discussion: In our study, colistin, tigecycline and netilmycin are the most
Kuah, B G; Kumarasinghe, G; Doran, J; Chang, H R
The in vitro activities of 17 antimicrobial agents alone or in combination against 70 clinical isolates of Acinetobacter baumannii from Singapore were determined by broth microdilution. The MICs of amoxicillin, ampicillin, ceftazidime, ceftriaxone, gentamicin, and piperacillin for 90% of the strains were > or = 128 micrograms/ml. Addition of sulbactam to ampicillin produced improved activity, whereas adding tazobactam to piperacillin did not. The MICs of amikacin, ciprofloxacin, and imipenem for 90% of the strains were 32, 32, and 16 micrograms/ml, respectively. PMID:7840598
Fitness cost associated with resistance to fluoroquinolones was recently shown to vary across clones of methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase-producing Klebsiella pneumoniae. The resulting dissimilar fitness should have influenced the clonal dynamics and thereby the rates of resistance for these pathogens. Moreover, a similar mechanism was recently proposed for the emergence of the H30 and H30R lineages of ESBL-producing E. coli and the major international clone (ribotype 027) of Clostridium difficile. Furthermore, several additional international clones of various multiresistant bacteria are suspect to have been selected by an analogous process. An ability to develop favorable mutations in the gyrase and topoisomerase IV genes seems to be a prerequisite for pathogens to retain fitness while showing high-level resistance to fluoroquinolones. Since, the consumption of other "non-fluoroquinolone" groups of antibiotics have also contributed to the rise in resistance rates a more judicious use of antibiotics in general and of fluoroquinolones in particular could ameliorate the international resistance situation. PMID:27458434
Toscani, Lucia; Guarducci, Diletta; Matà, Sabrina; Furlan, Tiziana; Ballo, Piercarlo
In this report, we describe a case of acute motoral axonal neuropathy (AMAN) following septic shock due to Acinetobacter baumannii. The aetiology of AMAN is still not fully clarified. An association with a potential infection by Campylobacter jejuni, resulting in stimulation of autoimmune response against gangliosides mediated by a phenomenon of molecular mimicry, is believed to play a major role. Since the lipopolysaccharide of A. baumannii has a structure that is similar to that of C. jejuni, we hypothesise that the infection by A. baumannii in our patient may have had a pathogenic role in the development of the neurological picture via a mechanism of molecular mimicry. PMID:26700086
Full Text Available Bacterial strains which possess genes to produce ESBL most often are multiresistant and also carry genes responsible for the resistance to most other antibiotics, including aminoglycosides, sulfamethoxazole+trimethoprim and fluoroquinolones. Therefore, practically the biggest contemporary clinical problem are infections of humans and animals caused by ESBL-producing strains of E. coli, Kleibsiella, Enterobacter, Proteus, Serratia, Citrobacter, Salmonella and Shigella species. The investigation of the ESBL presence was completed on multiresistant E. coli and Salmonella strains originating from dogs, cats, cattle, sheep, goats, pigs and poultry. The investigated strains were isolated from ear, skin, vaginal, faecal, urine, egg and eggshell swabs, from healthy and diseased individual animals of various ages and breed categories. The sum of 112 E. coli and 45 Salmonella strains was investigated. All strains resistant to 3 or more antibiotics were categorized as multiresistant, which led to a conclusion that 35 E. coli and 6 Salmonella strains out of all investigated were multiresistant to antibiotics. The largest number of multiresistant E. coli strains was discovered in cattle - 12 in total, and the minimal number in goats and sheep, with two strains each. All multiresistant Salmonella strains belonged to the Salmonella Enteritidis species (S. enterica subsp. enterica serovar Enteritidis. The sum of multiresistant Salmonella strains compared to all investigated strains was relatively low (13.3%, but the resistance prevalence for some antibiotics in these strains was extremely high, for ampicillin and amoxicillin with clavulanic acid as high as 100%, and for tetracycline 83.3%. For the control in this investigation were used ESBL positive E. coli strains originated in human urine specimens. No presence of positive ESBL strains was established. However, when the screening investigation was performed, almost all the strains were suspect, thus a
Davis, Emily; Scaletti-Hutchinson, Emma; Opel-Reading, Helen; Nakatani, Yoshio; Krause, Kurt L.
Acinetobacter baumannii is an opportunistic Gram-negative bacterium which is a common cause of hospital-acquired infections. Numerous antibiotic-resistant strains exist, emphasizing the need for the development of new antimicrobials. Alanine racemase (Alr) is a pyridoxal 5′-phosphate dependent enzyme that is responsible for racemization between enantiomers of alanine. As d-alanine is an essential component of the bacterial cell wall, its inhibition is lethal to prokaryotes, making it an excellent antibiotic drug target. The crystal structure of A. baumannii alanine racemase (AlrAba) from the highly antibiotic-resistant NCTC13302 strain has been solved to 1.9 Å resolution. Comparison of AlrAba with alanine racemases from closely related bacteria demonstrates a conserved overall fold. The substrate entryway and active site of the enzymes were shown to be highly conserved. The structure of AlrAba will provide the template required for future structure-based drug-design studies. PMID:25195891
Wieczorek, Piotr; Sacha, Paweł; Czaban, Sławomir; Hauschild, Tomasz; Ojdana, Dominika; Kowalczuk, Oksana; Milewski, Robert; Poniatowski, Bogusław; Nikliński, Jacek; Tryniszewska, Elżbieta
Acinetobacter baumannii has emerged as a highly problematic hospital-associated pathogen. Different mechanisms contribute to the formation of multidrug resistance in A. baumannii, including the AdeABC efflux system. Distribution of the structural and regulatory genes encoding the AdeABC efflux system among genetically diverse clinical A. baumannii strains was achieved by using PCR and pulsed-field gel electrophoresis techniques. The distribution of adeABRS genes is extremely high among our A. baumannii strains, except the adeC gene. We have observed a large proportion of strains presenting multidrug-resistance phenotype for several years. The efflux pump could be an important mechanism in these strains in resistance to antibiotics. PMID:23886790
Roux, Fabrice; Camilleri, Christine; Giancola, Sandra; Brunel, Dominique; Reboud, Xavier
The type of interactions among deleterious mutations is considered to be crucial in numerous areas of evolutionary biology, including the evolution of sex and recombination, the evolution of ploidy, the evolution of selfing, and the conservation of small populations. Because the herbicide resistance genes could be viewed as slightly deleterious mutations in the absence of the pesticide selection pressure, the epistatic interactions among three herbicide resistance genes (acetolactate synthase CSR, cellulose synthase IXR1, and auxin-induced AXR1 target genes) were estimated in both the homozygous and the heterozygous states, giving 27 genotype combinations in the model plant Arabidopsis thaliana. By analyzing eight quantitative traits in a segregating population for the three herbicide resistances in the absence of herbicide, we found that most interactions in both the homozygous and the heterozygous states were best explained by multiplicative effects (each additional resistance gene causes a comparable reduction in fitness) rather than by synergistic effects (each additional resistance gene causes a disproportionate fitness reduction). Dominance coefficients of the herbicide resistance cost ranged from partial dominance to underdominance, with a mean dominance coefficient of 0.07. It was suggested that the csr1-1, ixr1-2, and axr1-3 resistance alleles are nearly fully recessive for the fitness cost. More interestingly, the dominance of a specific resistance gene in the absence of herbicide varied according to, first, the presence of the other resistance genes and, second, the quantitative trait analyzed. These results and their implications for multiresistance evolution are discussed in relation to the maintenance of polymorphism at resistance loci in a heterogeneous environment. PMID:16020787
Akinduti, Paul Akinniyi; Aboderin, Bukola W; Oloyede, Rasaq; Ogiogwa, Joseph I; Motayo, Babatunde O; Ejilude, Oluwaseun
Multi-resistant Escherichia coli (E. coli) strains co-harboring virulence genes is a cause of high morbidity in Abeokuta, Nigeria. This study was designed to determine some virulent factors among enteropathogenic E. coli in Abeokuta, Nigeria. Approximately non-repetitive 102 isolates of E. coli were recovered from clinical samples from two health facilities in Abeokuta. Biotyping using API and antibiotic susceptibility was determined, and eae and flic genes were assayed by PCR. Antibiotic resistance relatedness was performed by DendroUPGMA. Results showed that 48.0% and 52.0 % were intestinal and extra-intestinal E. coli, ampicillin recorded 100% resistance, amoxycilli/clavulanic acid 64.7%, cotrimoxazole 57.8% and 56.8% resistance against cefotaxime, at MIC >16 ug/mL, 100%, 57.8%, and 50% have MIC50 to ampicillin, tetracycline, and ceftazidime, while 74.5% and 48.0% have MIC90 to ampicillin and ceftazidime. Significant rates of 4.9%, 7.8%, and 9.8% flic, eae, and flic/eae genes were found in intestinal isolates, while 2.9%, 2.0%, and 3.9% were found in extra-intestinal (P < 0.05). Two major clades of the resistant isolates reveal significant antibiotic relatedness among intestinal and extra-intestinal isolates, at 54% resistance similarities with very high multi-antibiotic resistance index of 1.0 (MARI). A high rate of undetected virulent E. coli pathotypes with high resistance could trigger unprecedented morbidity and mortality, mostly among children and the elderly. PMID:26263915
Choi, Hee Kyoung; Kim, Young Keun; Kim, Hyo Youl; Uh, Young
Purpose 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. Materials and Methods We retrospectively reviewed patients' medical records who were treated with aerosolized colistin for the treatment of pneum...
Napier, Brooke A.; Burd, Eileen M.; Satola, Sarah W.; Cagle, Stephanie M.; Ray, Susan M; McGann, Patrick; Pohl, Jan; Lesho, Emil P.; Weiss, David S.
ABSTRACT The alarming rise in antibiotic resistance has led to an increase in patient mortality and health care costs. This problem is compounded by the absence of new antibiotics close to regulatory approval. Acinetobacter baumannii is a human pathogen that causes infections primarily in patients in intensive care units (ICUs) and is highly antibiotic resistant. Colistin is one of the last-line antibiotics for treating A. baumannii infections; however, colistin-resistant strains are becoming...
F Simsek; Gedik, H; M T Yildirmak; N E Iris; A Türkmen; ERSOY, A.; Ersöz, M; A Gücüyener
Purpose: To evaluate the outcomes of the patients who were infected with colistin-only-susceptible (COS) Acinetobacter baumannii and treated with either colistin monotherapy or colistin combined therapy. Materials and Methods: This retrospective case-control study was conducted in the training and research hospital with an 800 beds between August 2008 and December 2011. The patients, who were infected with COS A. baumannii and received either colistin monotherapy or colistin combined therapy,...
Zhijin Chen; Yu Chen; Yaogao Fang; Xiaotian Wang; Yanqing Chen; Qingsong Qi; Fang Huang; Xungang Xiao
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 antibi...
Saghar Hendiani; Ahya Abdi-Ali; Parisa Mohammadi
Introduction: Medical devices are made from a variety of materials such as polypropylene, polycarbonate, poly styrene, glass and etc. by attaching to this surfaces, Acinetobacter baumannii can form biofilms and then cause several device associated infections. Biofilms are communities of bacteria attached to the surfaces. In this study, biofilm formation ability in clinical isolates of Acinetobacter baumannii was assessed by two methods on different surfaces. Materials and methods: Biof...
Oh, Man Hwan; Lee, Je Chul; Kim, Jungmin; Choi, Chul Hee; Han, Kyudong
The traditional markerless gene deletion technique based on overlap extension PCR has been used for generating gene deletions in multidrug-resistant Acinetobacter baumannii. However, the method is time-consuming because it requires restriction digestion of the PCR products in DNA cloning and the construction of new vectors containing a suitable antibiotic resistance cassette for the selection of A. baumannii merodiploids. Moreover, the availability of restriction sites and the selection of re...
Buddha Bahadur Basnet
Full Text Available Infections due to Mutli Drug Resistant A. baumannii (MDRAB is now recognized as a major public health problem worldwide. The nosocomial infection due to MDRAB has leaded to increased in morbidity and mortality which has added noticeably to significant challenge to modern antibiotic therapy system. This is due to rapid phenomenon of A. baumannii to acquire antibiotic resistance. Thus, in this review the overview of current knowledge on epidemiology, infections, mechanism of resistance and effective treatment options are briefly highlighted.
Dong Ming Li
Full Text Available A 14-year-old girl presented with a 2-week history of progressive facial ulcerations that did not respond to cephalexin and topical dexamethasone. Biopsy on the ulcer showed rod-shaped bacteria and actinomycetes-like mycelia in the vessel walls and within thrombi. Tissue culture yielded Acinetobacter baumannii, which was resistant to cephalexin. A favourite outcome was achieved with minocycline treatment. This is the first case report of A. baumannii-related vasculitis.
Orsinger-Jacobsen, Samantha J.; Patel, Shenan S.; Vellozzi, Ernestine M.; Gialanella, Phillip; Nimrichter, Leonardo; Miranda, Kildare; Martinez, Luis R.
Acinetobacter baumannii is a frequent cause of hospital-acquired pneumonia, and has recently increased in incidence as the causative agent of severe disease in troops wounded in Afghanistan and Iraq. Clinical approaches are limited since A. baumannii strains isolated from patients are extremely resistant to current antimicrobials. A. baumannii can survive desiccation and during outbreaks has been recovered from various sites in the patients’ environment. To better understand its prevalence in...
Mohajeri, Parviz; Sharbati, Saba; Farahani, Abbas; Rezaei, Zhaleh
Background: 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. Materials and Methods: A total of 104 samples from teaching hospitals in Kermanshah, Iran, were collected during a 24 months period (2011-20...
Cohen Karen; van Zyl-Smit Richard; Bamford Colleen; Gounden Ronald; Maartens Gary
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 tobr...
Full Text Available Following a worldwide trend, infections caused by MDR OXA-type (Ambler class D carbapenemase-producing Acinetobacter baumannii are currently regarded as a clinical and epidemiological emergency in Brazil. OXA-producing A. baumannii strains have been identified in the states of Alagoas, Amazonas, Bahia, Distrito Federal, Espírito Santo, Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Paraná, Pernambuco, Rio de Janeiro, Rio Grande do Norte, Rio Grande do Sul, Santa Catarina and São Paulo. In some settings, the presence of OXA-23- and/or OXA-143 -producing A. baumannii (so far restricted to Brazil has been endemic and A. baumannii strains carrying blaOXA-23 genes have been detected in hospital wastewater effluents, hence a potential risk to the community and the environment. Although molecular typing by multilocus sequence typing (MLST - Bartual scheme, University of Oxford, http://pubmlst.org/abaumannii/ has revealed the international spread of a clonal complex (CC denominated CC92, in Brazil most OXA-23-producing A. baumannii belong to CC113, CC109 or CC104 clonal complexes. Finally, from a clinical point of view, the main problem of A. baumannii infections is the limited use of antibacterial agents with in vitro activity, often restricted to ampicillin/sulbactam, polymyxin B and/or colistin (polymyxin E.
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.
Richards, A M; Abu Kwaik, Y; Lamont, R J
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
Rasoulinejad, Samaneh; Gargari, Seyed Latif Mousavi
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. PMID:27234880
Dexter, Carina; Murray, Gerald L; Paulsen, Ian T; Peleg, Anton Y
Community-acquired Acinetobacter baumannii (CA-Ab) is a rare but serious cause of community-acquired pneumonia in tropical regions of the world. CA-Ab infections predominantly affect individuals with risk factors, which include excess alcohol consumption, diabetes mellitus, smoking and chronic lung disease. CA-Ab pneumonia presents as a surprisingly fulminant course and is characterized by a rapid onset of fever, severe respiratory symptoms and multi-organ dysfunction, with a mortality rate reported as high as 64%. It is unclear whether the distinct clinical syndrome caused by CA-Ab is because of host predisposing factors or unique bacterial characteristics, or a combination of both. Deepening our understanding of the drivers of overwhelming CA-Ab infection will provide important insights into preventative and therapeutic strategies. PMID:25850806
de Gouvêa Erika
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
AMK AL Jarousha
Full Text Available Background: To perform a prospective case control study of blood stream infection to determine the infection rate of Acinetobacter baumannii and the risk factors associated with mortality."nMethods: From February 2004 to January 2005, 579 consecutive episodes of blood stream infection were obtained at two neonatal intensive care units Al Nasser and Al Shifa hospitals in Gaza City. Forty (6.9% isolates of A. baumannii were obtained from the neonates under 28 d. Most of the isolates (92% were from hospitalized patients in the intensive care units."nResults: Community acquired infection was 8%. Sixty three percent of the patients were males. The isolates of A. baumannii were resistant to commonly used antibiotics while being sensitive to meropenem (92.5%, imipenem (90%, chloramphenicol (80%, ciprofloxacin (75%, gentamicin (57.5%, ceftriaxone (50%, amikacin (37.5%, cefuroxime and cefotaxime (35%. Over all crude mortality rate was 20% with much higher crude mortality among patients with nosocomial infection. Based on logistic regression, the following factors were statistically significant: weight < 1500g, age < 7 d, mean of hospitalization equal 20 days, antibiotic use, and mechanical ventilation, when compared to the control group (P< 0.05."nConclusion: Infection rate of nosocomial blood stream infection was considerable and alarming in neonatal intensive care unit infants and associated with a significant excess length of NICU stay and a significant economic burden.
Full Text Available The antimicrobial sensibility of Escherichia coli strains isolated from the uterine content of bitches was evaluated. Fifteen E. coli strains were tested in relation to their susceptibility to different antimicrobials. The results demonstrated 100% of resistance to all tested drugs, being a quite conflicting finding compared to other works, which observed variable resistance of those bacteria to different antimicrobials but not the same multi-resistance pattern. The detection of those multi-resistance strains configures a problem, with important implications on the antimicrobial therapy. Therefore, additional investigations for a best characterization and extension of this problem are needed.
Fernández, Javier; Montero, Ignacio; Martínez, Óscar; Fleites, Ana; Poirel, Laurent; Nordmann, Patrice; Rodicio, M Rosario
Twenty-one multiresistant Enterobacter cloacae isolates producing OXA-48 (n=10), CTX-M-15 (n=7) or both (n=4) β-lactamases were detected in a Spanish hospital during a 1-year period (June 2013 to June 2014). The isolates were also resistant to non-β-lactam antimicrobials, further complicating the therapeutic options. Genotyping of the isolates identified two major clones (ST74 and ST66) that caused prolonged outbreaks in different buildings of the hospital as well as some sporadic isolates (ST78, ST45 and ST295). Isolates belonging to clone 1 (n=7) were carbapenem-resistant and carried the bla(OXA-48) gene on a conjugative IncL/M plasmid of ca. 65 kb. Clone 2 isolates (n=11) were resistant to cefepime and harboured the bla(CTX-M-15) gene on an ca. 150-kb, non-conjugative plasmid of the IncF group, co-harbouring the qnrB and aac(6')-Ib-cr genes encoding quinolone resistance. Four clone 2 isolates were also resistant to carbapenems owing to the co-production of OXA-48. Most of the isolates were recovered from critically ill patients and were admitted to intensive care units; a single patient was transferred from another Spanish hospital. Intrahospital and interhospital dissemination of multiresistant E. cloacae isolates is of major clinical concern as it could lead to endemic nosocomial situations. PMID:26307466
Shimose, Luis A; Masuda, Eriko; Sfeir, Maroun; Berbel Caban, Ana; Bueno, Maria X; dePascale, Dennise; Spychala, Caressa N; Cleary, Timothy; Namias, Nicholas; Kett, Daniel H; Doi, Yohei; Munoz-Price, L Silvia
OBJECTIVE To concomitantly determine the differential degrees of air and environmental contamination by Acinetobacter baumannii based on anatomic source of colonization and type of ICU layout (single-occupancy vs open layout). DESIGN Longitudinal prospective surveillance study of air and environmental surfaces in patient rooms. SETTING A 1,500-bed public teaching hospital in Miami, Florida. PATIENTS Consecutive A. baumannii-colonized patients admitted to our ICUs between October 2013 and February 2014. METHODS Air and environmental surfaces of the rooms of A. baumannii-colonized patients were sampled daily for up to 10 days. Pulsed-field gel electrophoresis (PFGE) was used to type and match the matching air, environmental, and clinical A. baumannii isolates. RESULTS A total of 25 A. baumannii-colonized patients were identified during the study period; 17 were colonized in the respiratory tract and 8 were colonized in the rectum. In rooms with rectally colonized patients, 38.3% of air samples were positive for A. baumannii; in rooms of patients with respiratory colonization, 13.1% of air samples were positive (P=.0001). In rooms with rectally colonized patients, 15.5% of environmental samples were positive for A. baumannii; in rooms of patients with respiratory colonization, 9.5% of environmental samples were positive (P=.02). The rates of air contamination in the open-layout and single-occupancy ICUs were 17.9% and 21.8%, respectively (P=.5). Environmental surfaces were positive in 9.5% of instances in open-layout ICUs versus 13.4% in single-occupancy ICUs (P=.09). CONCLUSIONS Air and environmental surface contaminations were significantly greater among rectally colonized patients; however, ICU layout did not influence the rate of contamination. Infect Control Hosp Epidemiol 2016;37:777-781. PMID:27045768
Full Text Available Acinetobacter baumannii has been identified by the Infectious Diseases Society of America as one of the six pathogens that cause majority of hospital infections. Increased resistance of A.baumannii even to the latest generation of β-lactams like carbapenem is an immediate threat to mankind. As inner-membrane fraction plays a significant role in survival of A.baumannii, we investigated the inner-membrane fraction proteome of carbapenem-resistant strain of A.baumannii using Differential In-Gel Electrophoresis (DIGE followed by DeCyder, Progenesis and LC-MS/MS analysis. We identified 19 over-expressed and 4 down-regulated proteins (fold change>2, p<0.05 in resistant strain as compared to reference strain. Some of the upregulated proteins in resistant strain and their association with carbapenem resistance in A.baumannii are: i β-lactamases, AmpC and OXA-51: cleave and inactivate carbapenem ii metabolic enzymes, ATP synthase, malate dehydrogenase and 2-oxoglutarate dehydrogenase: help in increased energy production for the survival and iii elongation factor Tu and ribosomal proteins: help in the overall protein production. Further, entry of carbapenem perhaps is limited by controlled production of OmpW and low levels of surface antigen help to evade host defence mechanism in developing resistance in A.baumannii. Present results support a model for the importance of proteins of inner-membrane fraction and their synergistic effect in the mediation of resistance of A.baumannii to carbapenem.
Fazeli; Taraghian; Kamali; Poursina; Nasr Esfahani; Moghim
Background Multidrug resistant (MDR) and extensively drug resistant (XDR) Acinetobacter baumannii are among important causes of nosocomial infections and cause therapeutic problems worldwide. The emergence of extensively drug-resistant A. baumannii (XDRAB) cause serious threats to hospital acquired infections (HAI) worldwide and further limit the treatment options. Objectives The current study aimed to identify and isolate the MDR...
Full Text Available Acinetobacter baumannii is a ubiquitous pathogen that has emerged as a major cause of healthcare-associated infections. Acinetobacter baumannii usually causes respiratory tract, urinary tract, blood stream and surgical site infections. They are of increasing importance because of its ability to rapidly develop resistance to the major groups of antibiotics. There are few data available on the antimicrobial susceptibility of A. baumannii in Iran. During the period of study from July 2005 to November 2006, a total of 88 strains of A. baumannii were isolated from clinical specimens obtained from patients hospitalized in an Iranian 1000-bed tertiary care hospital. Conventional bacteriological methods were used for identification of A. baumannii. Susceptibility testing was performed by the method recommended by Clinical Laboratory and Standards Institute (CLSI. The majority of isolates were from respiratory tract specimens. The organism showed high rate of resistance to ceftriaxone (90.9%, piperacillin (90.9%, ceftazidime (84.1%, amikacin (85.2% and ciprofloxacin (90.9%. Imipenem was the most effective antibiotic against A. baumannii and the rate of resistance for imipenem was 4.5%. The second most effective antibiotic was tobramycin, and 44.3% of A. baumannii isolates were resistant to this antibiotic. In conclusion, our study showed that the rate of resistance in A. baumannii to imipenem was low. There was a significant relationship between demographic features of patients such as age, undergoing mechanical ventilation, length of hospital stay and drug resistance.
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.
Full Text Available Treatment of Acinetobacter baumannii meningitis is an important challenge due to the accumulation of resistance of this bacteria and low meningeal diffusion of several antimicrobial requiring use of an antimicrobial effective combination to eradicate these species. We report a case of Acinetobacter baumannii multidrug-resistant nosocomial meningitis which was successfully treated with intravenous and intrathecal colistin associated with rifampicin.
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)
Full Text Available Introduction Acinetobacter baumannii has attained an alarming level of resistance to antibacterial drugs. Clinicians are now considering the use of older agents or unorthodox combinations of licensed drugs against multidrug-resistant strains to bridge the current treatment gap. We investigated the in vitro activities of combination treatments that included colistin with vancomycin, norvancomycin or linezolid against multidrug-resistant Acinetobacter baumannii. Methods The fractional inhibitory concentration index and time-kill assays were used to explore the combined effects of colistin with vancomycin, norvancomycin or linezolid against 40 clinical isolates of multidrug-resistant Acinetobacter baumannii. Transmission electron microscopy was performed to evaluate the interactions in response to the combination of colistin and vancomycin. Results The minimum inhibitory concentrations (MICs of vancomycin and norvancomycin for half of the isolates decreased below the susceptibility break point, and the MIC of linezolid for one isolate was decreased to the blood and epithelial lining fluid concentration using the current dosing regimen. When vancomycin or norvancomycin was combined with subinhibitory doses of colistin, the multidrug-resistant Acinetobacter baumannii test samples were eradicated. Transmission electron microscopy revealed that subinhibitory doses of colistin were able to disrupt the outer membrane, facilitating a disruption of the cell wall and leading to cell lysis. Conclusions Subinhibitory doses of colistin significantly enhanced the antibacterial activity of vancomycin, norvancomycin, and linezolid against multidrug-resistant Acinetobacter baumannii.
Rolain, J-M; Loucif, L; Al-Maslamani, M; Elmagboul, E; Al-Ansari, N; Taj-Aldeen, S; Shaukat, A; Ahmedullah, H; Hamed, M
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 (bla OXA-23, bla OXA-24, bla OXA-58, bla NDM) was investigated by real-time PCR. The epidemiologic relatedness of the isolates was verified by phylogenetic analysis based on partial sequences of CsuE and bla OXA-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 bla OXA-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. PMID:27054039
Thi Khanh Nhu, Nguyen; Riordan, David W; Do Hoang Nhu, Tran; Thanh, Duy Pham; Thwaites, Guy; Huong Lan, Nguyen Phu; Wren, Brendan W; Baker, Stephen; Stabler, Richard A
Acinetobacter baumannii is a significant cause of opportunistic hospital acquired infection and has been identified as an important emerging infection due to its high levels of antimicrobial resistance. Multidrug resistant A. baumannii has risen rapidly in Vietnam, where colistin is becoming the drug of last resort for many infections. In this study we generated spontaneous colistin resistant progeny (up to >256 μg/μl) from four colistin susceptible Vietnamese isolates and one susceptible reference strain (MIC <1.5 μg/μl). Whole genome sequencing was used to identify single nucleotide mutations that could be attributed to the reduced colistin susceptibility. We identified six lpxACD and three pmrB mutations, the majority of which were novel. In addition, we identified further mutations in six A. baumannii genes (vacJ, pldA, ttg2C, pheS and conserved hypothetical protein) that we hypothesise have a role in reduced colistin susceptibility. This study has identified additional mutations that may be associated with colistin resistance through novel resistance mechanisms. Our work further demonstrates how rapidly A. baumannii can generate resistance to a last resort antimicrobial and highlights the need for improved surveillance to identified A. baumannii with an extensive drug resistance profile. PMID:27329501
Raka, Lul; Kalenć, Smilja; Bosnjak, Zrinka; Budimir, Ana; Katić, Stjepan; Sijak, Dubravko; Mulliqi-Osmani, Gjyle; Zoutman, Dick; Jaka, Arbëresha
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 Acinetobacter baumannii 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. PMID:20464330
Filipović Irina; Mišić D.; Ašanin Ružica
Bacterial strains which possess genes to produce ESBL most often are multiresistant and also carry genes responsible for the resistance to most other antibiotics, including aminoglycosides, sulfamethoxazole+trimethoprim and fluoroquinolones. Therefore, practically the biggest contemporary clinical problem are infections of humans and animals caused by ESBL-producing strains of E. coli, Kleibsiella, Enterobacter, Proteus, Serratia, Citrobacter, Salmonella and Shigella species. The investigatio...
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.
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
Full Text Available Nosocomial meningitis is a rare complication of combined craniofacial and neurosurgical procedures. The increase in meningitis caused by multidrug-resistant (MDR Acinetobacter baumannii has resulted in a significant reduction in available treatment options. We report a case of 52-year-old man who sustained a complex craniofacial trauma, who developed nosocomial MDR infection caused by A. baumannii in the wound. Patient was at significant risk of developing meningitis but, he was successfully treated with intravenous colistin. To conclude, patients with complex maxillofacial trauma are at high risk of MDR A. baumannii meningitis, especially in craniofacial intensive care units, and adequate infection control measures with proper institution of antibiotics, should be used to reduce the risk of this infection
Sandra Yamile Saavedra
Full Text Available Nosocomial infections caused by carbapenem-resistant Acinetobacter baumannii isolates have reached epidemic levels in past decades. Currently this microorganism is responsible for outbreaks of difficult eradication and with high mortality rates worldwide. We herein report a rare case of an OXA-72-producing A. baumannii isolate colonizing a 47-year-old male patient with peritonitis due to abdominal stab wound, four years earlier than the first report of this carbapenemase in Acinetobacter pittii in Colombia. Although OXA-72 presents a low prevalence compared with OXA-23, our study demonstrated that A. baumannii isolates carrying the blaOXA-72 gene were present in the hospital environment in Colombia and could act as a reservoir for further spread to other Acinetobacter species, like A. pittii, causing carbapenem-resistance.
Ana Milda Karsten Baumgart
Full Text Available Pseudomonas aeruginosa and Acinetobacter baumannii are Gram-negative bacilli that in the last decades have become prevalent agents of hospital infection due to high antimicrobial resistance developed by these microorganisms. The present study is a retrospective analysis of all positive cultures for these microorganisms in the period of January 2004 to December 2008. Resistance levels of A. baumannii and P. aeruginosa to carbapenems was high and showed a trend to increase during the period of study. In recent years the increasing incidence and resistance levels of A. baumannii and P. aeruginosa to the antimicrobials used for their treatment in the hospital setting underscores the relevance of infections caused by these bacteria. The selective pressure caused by indiscriminated use of broad-spectrum antibiotics in empirical hospital infections is probably the main reason for such an increase with the consequent impact upon patient morbidity and mortality
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.
In the current investigation nemonoxacin (NMX) was radiolabeled with 99mTc in the presence of stannous chloride dihydrate as reducing agent. Factors affecting the percent labeling yield of 99mTc-Nemonoxacin (99mTc-NMX) complex were studied in details. The labeled compound was radiochemically characterized and was stable for a time up to 4 h. The complex showed in vitro saturated binding with living multiresistant Staphylococcus aureus (MRSA) and penicillin-resistant Streptococci (PRSC). Biodistribution and imaging studies were performed. All results showed that 99mTc-NMX complex is a promising agent for MRSA and PRSC infection imaging and can differentiate between infected and sterile inflammations. (author)
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
Full Text Available Guoqing Wan,1,2 Lingao Ruan,2,3 Yu Yin,2,3 Tian Yang,2,3 Mei Ge,2 Xiaodong Cheng1,4 1School of Life Science and Technology, China Pharmaceutical University, Nanjing, 2Shanghai Laiyi Center for Biopharmaceutical R&D, 3School of Pharmacy, Shanghai Jiao Tong University, Shanghai, People’s Republic of China; 4Department of Integrative Biology & Pharmacology, The University of Texas Health Science Center, Houston, TX, USA Abstract: Acinetobacter baumannii resistance to carbapenem antibiotics is a serious clinical challenge. As a newly developed technology, silver nanoparticles (AgNPs show some excellent characteristics compared to older treatments, and are a candidate for combating A. baumannii infection. However, its mechanism of action remains unclear. In this study, we combined AgNPs with antibiotics to treat carbapenem-resistant A. baumannii (aba1604. Our results showed that single AgNPs completely inhibited A. baumannii growth at 2.5 µg/mL. AgNP treatment also showed synergistic effects with the antibiotics polymixin B and rifampicin, and an additive effect with tigecyline. In vivo, we found that AgNPs–antibiotic combinations led to better survival ratios in A. baumannii-infected mouse peritonitis models than that by single drug treatment. Finally, we employed different antisense RNA-targeted Escherichia coli strains to elucidate the synergistic mechanism involved in bacterial responses to AgNPs and antibiotics. Keywords: Acinetobacter baumannii, AgNPs, synergistic, antibiotic combination, antisense RNA
Oh, Man Hwan; Lee, Je Chul; Kim, Jungmin; Choi, Chul Hee; Han, Kyudong
The traditional markerless gene deletion technique based on overlap extension PCR has been used for generating gene deletions in multidrug-resistant Acinetobacter baumannii. However, the method is time-consuming because it requires restriction digestion of the PCR products in DNA cloning and the construction of new vectors containing a suitable antibiotic resistance cassette for the selection of A. baumannii merodiploids. Moreover, the availability of restriction sites and the selection of recombinant bacteria harboring the desired chimeric plasmid are limited, making the construction of a chimeric plasmid more difficult. We describe a rapid and easy cloning method for markerless gene deletion in A. baumannii, which has no limitation in the availability of restriction sites and allows for easy selection of the clones carrying the desired chimeric plasmid. Notably, it is not necessary to construct new vectors in our method. This method utilizes direct cloning of blunt-end DNA fragments, in which upstream and downstream regions of the target gene are fused with an antibiotic resistance cassette via overlap extension PCR and are inserted into a blunt-end suicide vector developed for blunt-end cloning. Importantly, the antibiotic resistance cassette is placed outside the downstream region in order to enable easy selection of the recombinants carrying the desired plasmid, to eliminate the antibiotic resistance cassette via homologous recombination, and to avoid the necessity of constructing new vectors. This strategy was successfully applied to functional analysis of the genes associated with iron acquisition by A. baumannii ATCC 19606 and to ompA gene deletion in other A. baumannii strains. Consequently, the proposed method is invaluable for markerless gene deletion in multidrug-resistant A. baumannii. PMID:25746991
Allen, C. Leigh; Gulick, Andrew M., E-mail: email@example.com [University at Buffalo, Buffalo, NY 14203 (United States)
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.
Choi, Ik Sung; Lee, Yu Ji; Wi, Yu Mi; Kwan, Byung Soo; Jung, Kae Hwa; Hong, Woong Pyo; Kim, June Myong
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. PMID:27423416
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
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
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.
Borbone, Sonia; Lupo, Agnese; Mezzatesta, Maria Lina; Campanile, Floriana; Santagati, Maria; Stefani, Stefania
This study was undertaken to test the in vitro activity of tigecycline against 117 clinically relevant Gram-positive pathogens and to correlate this activity with their resistance gene content. Overall, tigecycline showed a minimal inhibitory concentration (MIC) range of 0.015-0.5mg/L, able to inhibit potently all multiresistant streptococci, enterococci and MR staphylococci. Tigecycline was active against methicillin-resistant Staphylococcus aureus (MRSA) and enterococci, with MICs for 90% of the organisms (MIC(90)) of 0.25 mg/L and 0.12 mg/L, respectively, being more active than linezolid (MIC(90)=2 mg/L) and quinupristin/dalfopristin (MIC(90)=0.5 and 2-4 mg/L, respectively). Molecular characterisation of resistance determinants demonstrated the concomitant presence of different classes of genes: in particular, tet(M), erm(B) and erm(C) in Streptococcus agalactiae; tet(O), variably associated with different erm genes, in Streptococcus pyogenes; vanA, tet(M) and erm(B) in Enterococcus faecalis, and vanA and erm(B) in Enterococcus faecium. All the MRSA strains harboured SCCmec and erm genes and 50% possessed tet(K) with tet(M) genes. Staphylococcus epidermidis strains were only resistant to erythromycin. These results clearly demonstrate that tigecycline has a MIC(90) range of 0.015-0.5 mg/L both against tetracycline-susceptible and -resistant isolates carrying other resistance determinants, suggesting that this drug could play an important role in the treatment of infections caused by these multiresistant Gram-positive pathogens. PMID:17646087
Nilima V Telang
Full Text Available Acinetobacter baumannii is considered as an emerging nosocomial pathogen and is renowned for its multi-drug resistance. We report a case of community-acquired pan-resistant A. baumannii caused fulminating septicemia. The treatment failure led to death. The A. baumannii strain isolated from blood, pus, urine and tracheal aspirate was confirmed by 16S r-RNA sequence homology and found positive for metallo-β-lactamase IMP-1, and was found to be a strong biofilm producer. The isolate was only susceptible (moderately to colistin.
Full Text Available Indole, a derivative of the amino acid tryptophan, is a toxic signaling molecule, which can inhibit bacterial growth. To overcome indole-induced toxicity, many bacteria have developed enzymatic defense systems to convert indole to non-toxic, water-insoluble indigo. We previously demonstrated that, like other aromatic compound-degrading bacteria, Acinetobacter baumannii can also convert indole to indigo. However, no work has been published investigating this mechanism. Here, we have shown that the growth of wild-type A. baumannii is severely inhibited in the presence of 3.5 mM indole. However, at lower concentrations, growth is stable, implying that the bacteria may be utilizing a survival mechanism to oxidize indole. To this end, we have identified a flavoprotein oxygenase encoded by the iifC gene of A. baumannii. Further, our results suggest that expressing this recombinant oxygenase protein in Escherichia coli can drive indole oxidation to indigo in vitro. Genome analysis shows that the iif operon is exclusively present in the genomes of A. baumannii and Pseudomonas syringae pv. actinidiae. Quantitative PCR and Western blot analysis also indicate that the iif operon is activated by indole through the AraC-like transcriptional regulator IifR. Taken together, these data suggest that this species of bacteria utilizes a novel indole-detoxification mechanism that is modulated by IifC, a protein that appears to be, at least to some extent, regulated by IifR.
Lin, Guang-Huey; Chen, Hao-Ping; Shu, Hung-Yu
Indole, a derivative of the amino acid tryptophan, is a toxic signaling molecule, which can inhibit bacterial growth. To overcome indole-induced toxicity, many bacteria have developed enzymatic defense systems to convert indole to non-toxic, water-insoluble indigo. We previously demonstrated that, like other aromatic compound-degrading bacteria, Acinetobacter baumannii can also convert indole to indigo. However, no work has been published investigating this mechanism. Here, we have shown that the growth of wild-type A. baumannii is severely inhibited in the presence of 3.5 mM indole. However, at lower concentrations, growth is stable, implying that the bacteria may be utilizing a survival mechanism to oxidize indole. To this end, we have identified a flavoprotein oxygenase encoded by the iifC gene of A. baumannii. Further, our results suggest that expressing this recombinant oxygenase protein in Escherichia coli can drive indole oxidation to indigo in vitro. Genome analysis shows that the iif operon is exclusively present in the genomes of A. baumannii and Pseudomonas syringae pv. actinidiae. Quantitative PCR and Western blot analysis also indicate that the iif operon is activated by indole through the AraC-like transcriptional regulator IifR. Taken together, these data suggest that this species of bacteria utilizes a novel indole-detoxification mechanism that is modulated by IifC, a protein that appears to be, at least to some extent, regulated by IifR. PMID:26390211
Full Text Available Abstracts Background Acinetobacter baumannii is well-recognized as an important nosocomial pathogen, however, due to their intrinsic resistance to several antibiotics, treatment options are limited. Synergistic effects between antibiotics and medicinal plants, particularly their active components, have intensively been studied as alternative approaches. Methods Fifty-one ethanol extracts obtained from 44 different selected medicinal plant species were tested for resistance modifying agents (RMAs of novobiocin against A. baumannii using growth inhibition assay. Results At 250 μg/ml, Holarrhena antidysenterica, Punica granatum, Quisqualis indica, Terminalia bellirica, Terminalia chebula, and Terminalia sp. that possessed low intrinsic antibacterial activity significantly enhanced the activity of novobiocin at 1 μg/ml (1/8xminimum inhibitory concentration against this pathogen. Holarrhena antidysenterica at 7.8 μg/ml demonstrated remarkable resistant modifying ability against A. baumannii in combination with novobiocin. The phytochemical study revealed that constituents of this medicinal plant contain alkaloids, condensed tannins, and triterpenoids. Conclusion The use of Holarrhena antidysenterica in combination with novobiocin provides an effective alternative treatment for multidrug resistant A. baumannii infections.
Kroeger, Lisa A.; Hovde, Laurie B.; Mitropoulos, Isaac F.; Schafer, Jeremy; Rotschafer, John C.
Using an in vitro pharmacodynamic model, a multidrug-resistant strain of Acinetobacter baumannii was exposed to colistin methanesulfonate alone and in combination with ceftazidime. Pre- and postexposure colistin sulfate MICs were determined. A single daily dose of colistin methanesulfonate combined with continuous-infusion ceftazidime prevented regrowth and postexposure MIC increases.
Full Text Available Introduction: Medical devices are made from a variety of materials such as polypropylene, polycarbonate, poly styrene, glass and etc. by attaching to this surfaces, Acinetobacter baumannii can form biofilms and then cause several device associated infections. Biofilms are communities of bacteria attached to the surfaces. In this study, biofilm formation ability in clinical isolates of Acinetobacter baumannii was assessed by two methods on different surfaces. Materials and methods: Biofilm formation by 75 clinical isolates of A. baumannii was evaluated on polycarbonate surface (microtiter plate and polypropylene surface (falcon by crystal violet and 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl-2H-tetrazolium-5-carboxanilide salt (XTT tetrazolium sodium salt assay methods. Falcon or tube method was carried out under static and agitation conditions. Results: Results showed the most isolates can form biofilm but higher numbers of isolates form biofilm on polypropylene surface under agitation. XTT method confirmed strong biofilm formation ability of 10 isolates. Discussion and conclusion: Each of the two assays showed an excellent applicability for the quantification of biofilms. The Crystal violet assay is cheap, easy and is usually used for the quantification of biofilms formed by microorganisms but XTT is more reliable and repeatable. Most of A. baumannii isolates have potential to form biofilm on the medical devices which may result in device-associated infections.
Deveci, Aydin; Coban, Ahmet Yilmaz; Acicbe, Ozlem; Tanyel, Esra; Yaman, Gorkem; Durupinar, Belma
Treatment of multidrug resistant (MDR) Acinetobacter baumannii infections causes some problems as a result of possessing various antibacterial resistance mechanisms against available antibiotics. Combination of antibiotics, acting by different mechanisms, is used for the treatment of MDR bacterial infections. It is an important factor to determine synergy or antagonism between agents in the combination for the constitution of effective therapy. The study aimed to determine In vitro interactions interpreted according to calculated fractional inhibitory concentration (FIC) index between sulbactam and ceftazidime, ceftriaxone, cefepime, ciprofloxacin, gentamicin, meropenem, tigecycline, and colistin. Ten clinical isolates of A. baumannii were tested for determination of synergistic effects of sulbactam with different antimicrobial combinations. Minimal inhibitory concentration (MIC) values of both sulbactam and combined antibiotics decreased 2- to 128-fold. Synergy and partial synergy were determined in combination of sulbactam with ceftazidime and gentamicin (FIC index: ≤ 0.5 or >0.5 to sulbactam. Although synergistic and partial synergistic effects were observed in the combination of sulbactam and ceftriaxone, all isolates remained resistant to ceftriaxone. The effect of cefepime-sulbactam combination was synergy in five, partial synergy in one and indifferent in four isolates. Meropenem and sulbactam showed a partial synergistic effect (FIC index: >0.5 to 1-2) in six isolates. Antagonism was not determined in any combination for clinical A. baumannii isolates in the study. In conclusion, sulbactam is a good candidate for combination treatment regimes for MDR A. baumannii infections. PMID:23182043
Tiwari, Monalisa; Roy, Ranita; Tiwari, Vishvanath
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. PMID:26910023
Ebrahim Babapour; Azam Haddadi; Reza Mirnejad; Seyed-Abdolhamid Angaji; Nour Amirmozafari
Objective: To check biofilm formation by Acinetobacter baumannii (A. baumannii) clinical isolates and show their susceptibility to different antibiotics and investigate a possible link between establishment of biofilm and multidrug resistance. Methods: This study was performed on clinical samples collected from patients with nosocomial infections in three hospitals of Tehran. Samples were initially screened by culture and biochemical tests for the presence of different species of Acinetobacter. Iden-tifications were further confirmed by PCR assays. Their susceptibilities to 11 antibiotics of different classes were determined by disc diffusion method according to Clinical and Laboratory Standards Institute guidelines. The ability to produce biofilm was investigated using methods:culture on Congo red agar, microtiter plate, and test tube method. Results: From the overall clinical samples, 156 specimens were confirmed to contain A. baumannii. The bacteria were highly resistant to most antibiotics except polymyxin B. Of these isolates, 10.26% were able to produce biofilms as shown on Congo red agar. However, the percentage of bacteria with positive biofilm in test tube, standard microtiter plate, and modified microtiter plate assays were 48.72%, 66.66%, and 73.72%, respec-tively. At least 92%of the biofilm forming isolates were multidrug resistant. 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.
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
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
Willems, Stefanie; Kampmeier, Stefanie; Bletz, Stefan; Kossow, Annelene; Köck, Robin; Kipp, Frank; Mellmann, Alexander
We characterized two epidemiologically similar Acinetobacter baumannii clusters from two separate intensive care units (ICU) using core genome multilocus sequence typing. Clonal spread was confirmed in ICU-1 (12 of 14 isolates shared genotypes); in ICU-2, all genotypes (13 isolates) were diverse, thus excluding transmissions and enabling adequate infection control measures. PMID:27358465
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.
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.
Qu, Junyan; Du, Yu
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. PMID:27144176
Segal, Heidi; Nelson, E C; Elisha, B. Gay
An ampC gene was cloned from a clinical isolate of Acinetobacter baumannii (strain RAN). DNA sequencing and primer extension studies showed that ampC is transcribed from a promoter contained within a putative insertion sequence element which has been found to abut several different genes in Acinetobacter spp.
Sefid, Fatemeh; Rasooli, Iraj; Jahangiri, Abolfazl; Bazmara, Hadise
Multidrug-resistant Acinetobacter baumannii is recognized to be among the most difficult antimicrobial-resistant gram negative bacilli to control and treat. One of the major challenges that the pathogenic bacteria face in their host is the scarcity of freely available iron. To survive under such conditions, bacteria express new proteins on their outer membrane and also secrete iron chelators called siderophores. Antibodies directed against these proteins associated with iron uptake exert a bacteriostatic or bactericidal effect against A. baumanii in vitro, by blocking siderophore mediated iron uptake pathways. Attempts should be made to discover peptides that could mimic protein epitopes and possess the same immunogenicity as the whole protein. Subsequently, theoretical methods for epitope prediction have been developed leading to synthesis of such peptides that are important for development of immunodiagnostic tests and vaccines. The present study was designed to in silico resolving the major obstacles in the control or in prevention of the diseases caused by A. baumannii. We exploited bioinformatic tools to better understand and characterize the Baumannii acinetobactin utilization structure of A. baumannii and select appropriate regions as effective B cell epitopes. In conclusion, amino acids 26-191 of cork domain and 321-635 of part of the barrel domain including L4-L9, were selected as vaccine candidates. These two regions contain functional exposed amino acids with higher score of B cell epitopes properties. Majority of amino acids are hydrophilic, flexible, accessible, and favorable for B cells from secondary structure point of view. PMID:25840681
Tugba Arslan Gulen
Conclusion: Our results suggest that the occurrence of MDR A.baumannii bacteremia was related with the usage of the wide spectrum antibiotics, and mortality rates were increased in patients that high SAPS II scores, long term hospitalization. Infection control procedures and limited antibiotic usage are very important for prevent nosocomial infections.
SHI Wei-feng; JIANG Jian-ping; MI Zu-huang
Background Acinetobacter baumannii is one of the main gram-negative bacilli in clinical practice. Nosocomial infections caused by multi-drug resistance Acinetobacter baumannii is very difficult to treat. This study was designed to investigate the antimicrobial resistance characteristics and four resistant gene expressions of aminoglycoside-modifying enzymes including N-acetyltransferases and O-phosphotransferases in Acinetobacter baumannii. Methods Bacterial identification and antimicrobial susceptibility test were performed by PhoenixTM system in 247 strains of Acinetobacter baumannii. Minimal inhibitory concentrations (MICs) of seven aminoglycosides including gentamicin, amikacin, kanamycin, tobramycin, netilmicin, neomycin and streptomycin in 15 strains of multi-drug resistant Acinetobacter baumannii were detected by agar dilution. Four aminoglycoside-modifying enzyme genes were amplified by polymerase chain reaction (PCR) and verified by DNA sequencer.Results The resistance rates of 247 strains of Acinetobacter baumannii against cefotaxime, levofloxacin, piperacillin, aztreonam, tetracycline, ciprofloxacin and chloramphenicol were more than 50%. Imipenem and meropenem showed high antibacterial activities with resistance rates of 3.2% and 4.1%. MIC50 and MIC90 of gentamicin, amikacin, streptomycin and kanamycin in 15 strains of multi-drug resistant Acinetobacter baumanii were all more than 1024 mg/L, and the resistance rates were 100%, 100%, 100% and 93.3%, respectively. But their resistance rates to tobramycin, netilmicin and neomycin were 86.7%, 93.3% and 46.7%, respectively. Three modifying enzyme genes, including aacC1, aacC2 and aacA4 genes, were found in 15 strains, but aphA6 had not been detected. Their positive rates were 93.3%, 20.0% and 20.0%, respectively. These three genes existed simultaneously in No.19 strain. Nucleotide sequences of aacC1, aacC2 and aacA4 genes shared 100%, 97.9% and 99.7% identities with GenBank genes (AY307113, S68058 and AY
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
Martins, Liliana Raquel Leite; Pina, Susana Maria Rocha; Simões, Romeo Luís Rocha; de Matos, Augusto José Ferreira; Rodrigues, Pedro; da Costa, Paulo Martins Rodrigues
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. PMID:23397653
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.
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.
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.
Full Text Available OBJECTIVE: Acinetobacter baumannii is considered the prototypical example of a multi- or pan- drug-resistant bacterium. It has been increasingly implicated as a major cause of nosocomial and community-associated infections. This study proposed to evaluate the efficacy of immunological approaches to prevent and treat A. baumannii infections. METHODS: Mice were immunized with outer membrane vesicles (OMVs prepared from a clinically isolated multidrug-resistant strain of A. baumannii. Pneumonia and sepsis models were used to evaluate the efficacy of active and passive immunization with OMVs. The probable effective mechanisms and the protective potential of clonally distinct clinical isolates were investigated in vitro using an opsonophagocytic assay. RESULTS: Intramuscular immunization with OMVs rapidly produced high levels of OMV-specific IgG antibodies, and subsequent intranasal challenge with A. baumannii elicited mucosal IgA and IgG responses. Both active and passive immunization protected the mice from challenges with homologue bacteria in a sepsis model. Bacterial burden in bronchoalveolar lavage fluids (BALF, lung, and spleen, inflammatory cell infiltration in BALF and lung, and inflammatory cytokine accumulation in BALF was significantly suppressed in the pneumonia model by both active and passive immunization strategies. The antisera from immunized mice presented with significant opsonophagocytic activities in a dose-dependent manner against not only homologous strains but also five of the other six clonally distinct clinical isolates. CONCLUSIONS: Utilizing immunological characteristics of outer membrane proteins to elevate protective immunity and circumvent complex multidrug-resistance mechanisms might be a viable approach to effectively control A. baumannii infections.
Schaufler, Katharina; Bethe, Astrid; Lübke-Becker, Antina; Ewers, Christa; Kohn, Barbara; Wieler, Lothar H; Günther, Sebastian
Introduction: To contribute to the understanding of multiresistant bacteria, a ‘One Health’ approach in estimating the rate of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and getting insights into the transmission from clinical settings to the surrounding environment was employed by collecting fecal samples of dogs in a public area. Isolates were compared to those from samples of diseased dogs from a nearby small-animal clinic.Materials and methods: One hundred fecal sa...
Mišić Dušan; Stošić Zorica; Kiškarolj Ferenc; Adamov Vladica; Ašanin Ružica
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: Salm...
Schwartz, Thomas; Armant, Olivier; Bretschneider, Nancy; Hahn, Alexander; Kirchen, Silke; Seifert, Martin; Dötsch, Andreas
The fitness of sensitive and resistant P seudomonas 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 is...
Eveillard, M; Eb, F; Tramier, B; Schmit, J L; Lescure, F X; Biendo, M; Canarelli, B; Daoudi, F; Laurans, G; Rousseau, F; Thomas, D
From February 1999 to January 2000, a control programme to prevent the spread multi-resistant bacteria (MRB) was implemented in a French teaching hospital. This programme focused on methicillin-resistant Staphylococcus aureus (MRSA) and Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBL), and was based on the application of barrier precautions (washing hands with antiseptic soaps, wearing disposable gloves and gowns, identifying MRB carriers). No changes in antibiotic policy occurred during the year. Our aim was to conduct an evaluation of this programme by measuring incidence rates. Concurrently, the effect of barrier precautions was estimated in an indirect way, by documenting the availability of barrier precautions in MRB carriers' rooms and by analysing the monthly correlation between the supply of such material and the theoretical cumulated length of MRB carriers' isolation in six randomized wards. All MRB isolated in hospitalized patients were recorded, and differentiated between acquisition in our hospital or from elsewhere. For the analysis of trends, the year was divided in three periods of four months. Over the year, the global MRB incidence was 1.26 per 1000 patient-days (PD) [95% confidence interval (95%CI)=1.16-1.36]. The MRSA incidence was 0.89 per 1000 PD (95%CI=0.81- 0.97) and the ESBL incidence was 0.38 per 1000 PD (95% CI=0.33-0.43). The MRB incidence decreased significantly in all types of specialties except for surgical wards. The incidence decreased by 17.9% for MRSA, 54.9% for ESBL and 34.8% for both MRB. Concurrently, the proportion of strains acquired in our hospital decreased for MRSA (P for trend > or = 0.05) and ESBL (P for trend > or = 0.01), whereas the incidence of imported strains increased slightly. The proportion of multiresistant strains in S. aureus (36.8%) and Enterobacter aerogenes (37.0%) remained similar throughout the year. Thus, the decrease of the incidence concerned both resistant and susceptible strains
Batarseh, A; Al-Sarhan, A; Maayteh, M; Al-Khatirei, S; Alarmouti, M
This study was conducted to determine the prevalence and the local antibiogram of multidrug-resistant Acinetobacter baumannii isolates in Al-Hussein Hospital at King Hussein Medical Centre in Amman, Jordan. In a retrospective study from January to December 2013, data on 116 non-repetitive positive clinical samples were retrieved from patients' laboratory records. The resistance rates of A. baumannii isolates were high for ceftriaxone, cefotaxime and ticarcillin (100%), ceftazidime, cefepime and piperacillin (98.3%), imipenem (97.4%), piperacillin/tazobactam (96.6%), quinolones (94.8%), ampicillin/sulbactam (89.7%), gentamicin, (87.9%), tobramycin and tetracycline (76.7%) and trimethoprim/sulfamethoxazole (75.9%), but lower for minocycline (26.7%) and colistin (1.7%). A. baumannii in our hospital were highly resistant to all antibiotics, including tigecycline, except for minocycline and colistin which are considered the last resort treatment for multidrug-resistant A. baumannii. PMID:26857720
Li, X; Quan, J; Yang, Y; Ji, J; Liu, L; Fu, Y; Hua, X; Chen, Y; Pi, B; Jiang, Y; Yu, Y
Acinetobacter baumannii, a non-fermenting gram-negative coccobacillus, is a major pathogen responsible for a variety of healthcare-associated infections, including pneumonia, urinary tract and bloodstream infections. Moreover, A. baumannii is associated with alarming increases in drug resistance rates to almost all available antibiotics leaving limited treatment options. Here, we characterize the biological functions of a novel gene, abrp, which encodes a peptidase C13 family. We demonstrate that the abrp is associated with decreased susceptibility to tetracycline, minocycline, doxycycline, tigecycline, chloramphenicol and fosfomycin. Deletion of abrp was able to increase cell membrane permeability and display slower cell growth rate. Results from the present study show that abrp plays an important role in conferring reduced susceptibility to different classes of antibiotics and cell growth in A. baumannii. The change of antibiotic sensitivities may result from modifications to the cell membrane permeability of A. baumannii. PMID:27220329
Li Jian; Zhu De-mei; Huang Jun; Liu Xiao-fang; Liang Wang; Zhang Jing
Abstract Background Extensive drug resistance of Acinetobacter baumannii is a serious problem in the clinical setting. It is therefore important to find active antibiotic combinations that could be effective in the treatment of infections caused by this problematic 'superbug'. In this study, we analyzed the in vitro activities of three colistin-based combinations and a minocycline-based combination against clinically isolated extensive drug resistant Acinetobacter baumannii (XDR-AB) strains. ...
Bhargava, Nidhi; Sharma, Prince; Capalash, Neena
Acinetobacter baumannii and Pseudomonas aeruginosa are nosocomial pathogens with overlapping sites of infection. This work reports that the two can coexist stably in mixed-culture biofilms. In a study intended to improve our understanding of the mechanism of their coexistence, it was found that pyocyanin, produced by P. aeruginosa that generally eliminates competition from other pathogens, led to the generation of reactive oxygen species (ROS) in A. baumannii cells, which in response showed a significant (P ≤ 0.05) increase in production of enzymes, specifically, catalase and superoxide dismutase (SOD). This work shows for the first time that the expression of catalase and SOD is under the control of a quorum-sensing system in A. baumannii. In support of this observation, a quorum-sensing mutant of A. baumannii (abaI::Km) was found to be sensitive to pyocyanin compared to its wild type and showed significantly (P ≤ 0.001) lower levels of the antioxidant enzymes, which increased on addition of 5 μM N-(3-hydroxydodecanoyl)-l-homoserine lactone. Likewise, in wild-type A. baumannii, there was a significant (P quencher of quorum sensing. In the presence of amikacin and carbenicillin, A. baumannii formed 0.07 and 0.02% persister cells, which increased 4- and 3-fold, respectively, in the presence of pyocyanin. These findings show that pyocyanin induces a protective mechanism in A. baumannii against oxidative stress and also increases its persistence against antibiotics which could be of clinical significance in the case of coinfections with A. baumannii and P. aeruginosa. PMID:24891106
Abdi-Ali, Ahya; Hendiani, Saghar; Mohammadi, Parisa; Gharavi, Sara
Background: Biofilms are communities of bacteria attached to the surfaces in an extracellular polymeric matrix which are associated with many chronic infections in humans. Acinetobacter spp. are emerging as a major cause of nosocomial infections and Acinetobacter baumannii is the predominant species associated with this kind of infections. Objectives: In the present study, the potential of biofilm formation of clinical isolates, A. baumannii, was assessed by using crystal violet method. Furth...
Saghi; Bahador; Khaledi; Ataee Kachoei; Amiri Dastjerdi; Esmaeili
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 Esc...
Jing Chen; Hong Li; Jinsong Yang; Rong Zhan; Aiping Chen; Yansheng Yan
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 Janua...
Full Text Available Background Multidrug resistant (MDR and extensively drug resistant (XDR Acinetobacter baumannii are among important causes of nosocomial infections and cause therapeutic problems worldwide. The emergence of extensively drug-resistant A. baumannii (XDRAB cause serious threats to hospital acquired infections (HAI worldwide and further limit the treatment options. Objectives The current study aimed to identify and isolate the MDR and XDR Acinetobacter baumannii from different wards of a teaching hospital in Isfahan, Iran, and determine the susceptibility pattern of these bacteria. Materials and Methods One hundred and twenty one (121 isolates of A. baumannii collected from a teaching hospital in Isfahan, Iran, within eight months (between September 2013 and April 2014 were included in the current study. The samples were isolated from different wards and different specimens. To confirm the species of A. baumannii, Polymerase chain reaction (PCRwas conducted to identify blaoxa-51 gene. Disk diffusion method was employed to evaluate antimicrobial susceptibility against cefotaxime, ceftriaxone, ampicillin-sulbactam, cefepime, meropenem, tobramycin, amikacin, tetracycline, ciprofloxacin, trimethoprim- sulfamethoxazole, and aztreonam. Results Among the 121 isolated A. baumannii, 44% and 56% were isolated from female and male, respectively. Samples cultured from the trachea (36%, urine (15%, blood (10%, wound (10%, cerebrospinal fluid (7%, bronchial (4% and the others (18%. Most of the isolates (50% were obtained from intensive care unit (ICU. Isolated A. baumannii showed high resistance to the evaluated antibiotics except ampicillin-sulbactam, which showed only 33.9% resistance. Also, 62.8% and 100% of the isolates were identified as XDR and MDR. Conclusions The result of the current study showed the growing number of nosocomial infections associated with XDR A. baumannii causing difficulties in antibiotic therapy. Resistant strains increasingly cause
Al-Sultan, Abdulrahman A.; Evans, Benjamin A.; Aboulmagd, Elsayed; Al-Qahtani, Ahmed A; Bohol, Marie Fe F.; Al-Ahdal, Mohammed N.; Opazo, Andres F.; Amyes, Sebastian G. B.
It has previously been shown that carbapenem-resistant Acinetobacter baumannii are frequently detected in Saudi Arabia. The present study aimed to identify the epidemiology and distribution of antibiotic resistance determinants in these bacteria. A total of 83 A. baumannii isolates were typed by pulsed-field gel electrophoresis (PFGE), and screened by PCR for carbapenemase genes and insertion sequences. Antibiotic sensitivity to imipenem, meropenem, tigecycline, and colistin were determined. ...
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
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. PMID:23070166
Volkow-Fernández Patricia; Rodríguez Cecilia Franco; Cornejo-Juárez Patricia
Abstract Introduction Acinetobacter baumannii is a Gram-negative bacteria and a significant nosocomial pathogen in hospitals. Multidrug-resistant A. baumannii have emerged as a cause of nosocomial infections in critically ill patients. This microorganism has the ability to produce biofilms on different surfaces, which could explain their ability to persist in clinical environments and their role in device-related infections. Case presentation We present the case of a 33-year-old Hispanic man ...
Phee, Lynette M.; Betts, Jonathan W.; Bharathan, Binutha; Wareham, David W.
The spread of multidrug-resistant Acinetobacter baumannii (MDRAB) has led to the renaissance of colistin (COL), often the only agent to which MDRAB remains susceptible. Effective therapy with COL is beset with problems due to unpredictable pharmacokinetics, toxicity, and the rapid selection of resistance. Here, we describe a potent synergistic interaction when COL was combined with fusidic acid (FD) against A. baumannii. Synergy in vitro was assessed against 11 MDRAB isolates using disc diffu...
Weiwei Huang; Yufeng Yao; Shijie Wang; Ye Xia; Xu Yang; Qiong Long; Wenjia Sun; Cunbao Liu; Yang Li; Xiaojie Chu; Hongmei Bai; Yueting Yao; Yanbing Ma
A. baumannii infections are becoming more and more serious health issues with rapid emerging of multidrug and extremely drug resistant strains, and therefore, there is an urgent need for the development of nonantibiotic-based intervention strategies. This study aimed at identifying whether an outer membrane protein with molecular weight of about 22 kDa (Omp22) holds the potentials to be an efficient vaccine candidate and combat A. baumannii infection. Omp22 which has a molecule length of 217 ...
Clinical outcomes of tigecycline alone or in combination with other antimicrobial agents for the treatment of patients with healthcare-associated multidrug-resistant Acinetobacter baumannii infections.
Lee, Y-T; Tsao, S-M; Hsueh, P-R
Tigecycline (TG) has been shown to be active in vitro against Acinetobacter baumannii, although data on the clinical efficacy of TG alone or in combination for the treatment of infections due to multidrug-resistant A. baumannii (MDRAB) remain limited. The purpose of this study was to investigate the clinical outcomes of patients with healthcare-associated infections (HAIs) caused by MDRAB who were treated with imipenem/cilastatin and sulbactam, and TG alone or in combination with other antibiotics. A total of 386 patients with HAIs caused by MDRAB were retrospectively analyzed and grouped into TG and non-TG groups, depending on whether they received TG treatment. Of the 266 patients in the TG group, 108 were treated with TG alone and 158 were treated with TG in combination with ceftazidime, ceftriaxone, piperacillin/tazobactam, or a carbapenem. All 120 patients in the non-TG group were treated with imipenem/cilastatin and sulbactam. The primary outcome measure was 30-day mortality after TG treatment and the secondary outcome was clinical outcome. There were no significant differences in survival rates between the two groups. However, the rate of unfavorable outcome was significantly lower (p < 0.05) among patients in the TG group than among patients in the non-TG group. The most significant predictor of unfavorable outcome was sepsis, whereas TG treatment and microbial eradication were the most significant predictors of favorable outcomes. Our study represents the largest study of patients with MDRAB infection treated with TG and expands our understanding of the role of TG therapy alone or in combination with other agents for the treatment of HAI caused by MDRAB. PMID:23553594
Soon, Rachel L; Nation, Roger L; Harper, Marina; Adler, Ben; Boyce, John D.; Tan, Chun-Hong; Jian LI; Larson, Ian
The diminishing antimicrobial development pipeline has forced the revival of colistin as a last line of defence against infections caused by multidrug-resistant Gram-negative ‘superbugs’ such as Acinetobacter baumannii. The complete loss of lipopolysaccharide (LPS) mediates colistin resistance in some A. baumannii strains. Atomic force microscopy was used to examine the surface properties of colistin-susceptible and -resistant A. baumannii strains at mid-logarithmic and stationary growth phas...
Lee, Hee Ji; Bergen, Phillip J.; Bulitta, Jurgen B.; Tsuji, Brian; Forrest, Alan; Nation, Roger L; Jian LI
Combination therapy may be required for multidrug-resistant (MDR) Acinetobacter baumannii. This study systematically investigated bacterial killing and emergence of colistin resistance with colistin and rifampin combinations against MDR A. baumannii. Studies were conducted over 72 h in an in vitro pharmacokinetic (PK)/pharmacodynamic (PD) model at inocula of ∼106 and ∼108 CFU/ml using two MDR clinical isolates of A. baumannii, FADDI-AB030 (colistin susceptible) and FADDI-AB156 (colistin resis...
Fernando, Dinesh M.; Xu, Wayne; Loewen, Peter C.; Zhanel, George G; Kumar, Ayush
In order to determine if triclosan can select for mutants of Acinetobacter baumannii ATCC 17978 that display reduced susceptibilities to antibiotics, we isolated a triclosan-resistant mutant, A. baumannii AB042, by serial passaging of A. baumannii ATCC 17978 in growth medium supplemented with triclosan. The antimicrobial susceptibility of AB042 was analyzed by the 2-fold serial dilution method. Expression of five different resistance-nodulation-division (RND) pump-encoding genes (adeB, adeG, ...
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.
Mathlouthi, Najla; El Salabi, Allaaeddin Ali; Ben Jomàa-Jemili, Mariem; Bakour, Sofiane; Al-Bayssari, Charbel; Zorgani, Abdulaziz A; Kraiema, Abdulmajeed; Elahmer, Omar; Okdah, Liliane; Rolain, Jean-Marc; Chouchani, Chedly
Acinetobacter baumannii is an opportunistic pathogen causing various nosocomial infections. The aim of this study was to characterise the molecular support of carbapenem-resistant A. baumannii clinical isolates recovered from two Libyan hospitals. Bacterial isolates were identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Antibiotic susceptibility testing was performed using disk diffusion and Etest methods, and carbapenem resistance determinants were studied by PCR amplification and sequencing. Multilocus sequence typing (MLST) was performed for typing of the isolates. All 36 imipenem-resistant isolates tested were identified as A. baumannii. The blaOXA-23 gene was detected in 29 strains (80.6%). The metallo-β-lactamase blaNDM-1 gene was detected in eight isolates (22.2%), showing dissemination of multidrug-resistant (MDR) A. baumannii in Tripoli Medical Center and Burn and Plastic Surgery Hospital in Libya, including one isolate that co-expressed the blaOXA-23 gene. MLST revealed several sequence types (STs). Imipenem-resistant A. baumannii ST2 was the predominant clone (16/36; 44.4%). This study shows that NDM-1 and OXA-23 contribute to antibiotic resistance in Libyan hospitals and represents the first incidence of the association of these two carbapenemases in an autochthonous MDR A. baumannii isolated from patients in Libya, indicating that there is a longstanding infection control problem in these hospitals. PMID:27216382
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.
Wintzell, My; Löfstedt, Lina; Johansson, Joel; Pedersen, Anne B; Fuxe, Jonas; Shoshan, Maria
Cisplatin is used in treatment of several types of cancer, including epithelial ovarian carcinoma (EOC). In order to mimic clinical treatment and to investigate longterm effects of cisplatin in surviving cancer cells, two EOC cell lines were repeatedly treated with low doses. In the SKOV-3 cell line originating from malignant ascites, but not in A2780 cells from a primary tumor, this led to emergence of a stable population (SKOV-3-R) which in the absence of cisplatin showed increased motility, epithelial-mesenchymal transition (EMT) and expression of cancer stem cell markers CD117, CD44 and ALDH1. Accordingly, the cells formed self-renewing spheres in serum-free stem cell medium. Despite upregulation of mitochondrial mass and cytochrome c, and no upregulation of Bcl-2/Bcl-xL, SKOV-3-R were multiresistant to antineoplastic drugs. Cancer stem cells, or tumor-initiating cells (TICs) are highly chemoresistant and are believed to cause relapse into disseminated and resistant EOC. Our second aim was therefore to target resistance in these TIC-like cells. Resistance could be correlated with upregulation of hexokinase-II and VDAC, which are known to form a survival-promoting mitochondrial complex. The cells were thus sensitive to 3-bromopyruvate, which dissociates hexokinase-II from this complex, and were particularly sensitive to combination treatment with cisplatin at doses down to 0.1 x IC 50. 3-bromopyruvate might thus be of use in targeting the especially aggressive TIC populations. PMID:22954696
Carvalho, Tiele; Van Der Sand, Sueli
Endophytic actinomycetes are promising sources of antimicrobial substances. This study evaluates the activity of metabolites produced by the endophytic actinomycete R18(6) against Gram-negative bacteria multiresistant to antimicrobials. R18(6) isolate was grown in submerged cultures under different conditions: carbon source, temperature, pH and incubation time to optimize antimicrobials production. The actinomycete grown in base medium supplemented with 1% glucose, pH 6.5 and incubation at 30 ºC for 96 h with shaking at 100 rpm, exhibited the highest activity against the used Gram-negative bacteria. Minimum inhibitory concentration (MIC) of the crude extract produced by the microorganism varied between 1/32 and 1/256. It had bactericide or bacteriostatic activity, depending on the Gram-negative organism. The active extract was stable at high temperatures, and unstable in medium containing proteolytic enzymes. Micromorphology of R18(6) was investigated by optical and scan microscopy, revealing that it was morphologically similar to the genusStreptomyces. PMID:26871499
The paper has a threefold purpose. The first purpose is to present an explicit description of expanded cyclic codes defined in $\\GF(q^m)$. The proposed explicit construction of expanded generator matrix and expanded parity check matrix maintains the symbol-wise algebraic structure and thus keeps many important original characteristics. The second purpose of this paper is to identify a class of constant-weight cyclic codes. Specifically, we show that a well-known class of $q$-ary BCH codes excluding the all-zero codeword are constant-weight cyclic codes. Moreover, we show this class of codes achieve the Plotkin bound. The last purpose of the paper is to characterize expanded cyclic codes utilizing the proposed expanded generator matrix and parity check matrix. We analyze the properties of component codewords of a codeword and particularly establish the precise conditions under which a codeword can be represented by a subbasis. With the new insights, we present an improved lower bound on the minimum distance of...
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
Othman, A., E-mail: firstname.lastname@example.org; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A. [Faculty of Electrical Engineering, Universiti Teknologi MARA Malaysia, 40450, Shah Alam, Selangor (Malaysia); Ain, M. F. [School of Electrical and Electronic Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300,Nibong Tebal, Pulau Pinang (Malaysia)
The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.
Moisoiu, Adriana; Ionită, Monica; Sârbu, Lăcrămioara; Stoica, Corina; Grigoriu, Liliana
Acinetobacter baumannii (A. baumannii) is one of the leading causes of morbidity and mortality in patients who are in critical condition in hospitals and especially in intensive care units (ICU). Long time considered a bacterium with low virulence, A. baumannii has more recently become a cause for major concern in clinical practice due to its high level of antimicrobial resistance. The extend of infections with Acinetobacter baumannii in ICU is caused by multiple factors, such as mechanical ventilation, invasive procedures, the use of a large number of broad spectrum antibiotics and transmission through the hands of medical staff In this study we evaluated the resistance to antibiotics of 213 non-duplicated strains of A. baumannii isolated in the bacteriology laboratory of the "Marius Nasta" lnstitute of Pneumophtisiology (IPMN) from January 2012 to December 2013. These strains originated from patients in medical wards (56), ICU (143) and surgery (14). Strains identification was performed by classical methods on multitest media and with API kits (Bio Merieux). The antibiotic sensitivity was performed on Mueller-Hinton media in accordance with CLSI2013. Analysis of the resistance to antibiotics was the following: carbenicilin (87.3%), ceftriaxone (87.3%), cefoperazone with sulbactam (84.9%), ceftazidime (79.3%), carbapenems (imipenem and/or meropenem--75.1%), fluoroquinolones (ciprofloxacin and/orlevofloxacin--73.7%), cefepime (66.6%), piperacilin with tazobactam (62.4%), amikacin (50.2%), netilmicin (45%), gentamicin (42.7%) and tobramycin (35.6%). In our study, we only found two strains of Acinetobacter baumannii with resistance to colistin and 70 (32.8%) strains sensitive only to colistin, but resistant to all other antibiotics tested. A. baumannii is a pathogen with rapid spread and extended resistance to even newer antimicrobial agents. Due to its ability to survive in the hospital environment, A. baumannii has the immense potential to cause nosocomial
Full Text Available Acinetobacter baumannii has been increasingly reported as a significant causative organism of various nosocomial infections. Here we describe three different outbreaks of multidrug resistant A. baumannii started in the Intensitive Care Unit and then involving other wards of San Carlo Borromeo hospital in Milan, Italy. In order to characterize the clinical strains isolates, molecular typing using semi-automated repetitive-sequence-based PCR (rep-PCR was performed.Among the sixty-one strains analyzed, three main cluster (C1, C2, C3 were detected: C1 included six indistinguishable strains, C2 five and C3 thirty. No correlation was observed between chemosensitivity and ribotyping pattern and an high rate of carbapenems resistance was founded.
Full Text Available Purpose: To evaluate the outcomes of the patients who were infected with colistin-only-susceptible (COS Acinetobacter baumannii and treated with either colistin monotherapy or colistin combined therapy. Materials and Methods: This retrospective case-control study was conducted in the training and research hospital with an 800 beds between August 2008 and December 2011. The patients, who were infected with COS A. baumannii and received either colistin monotherapy or colistin combined therapy, were included into the study. Results: In total, 51 patients fulfilling study criteria were evaluated. Colistin monotherapy was found effective as much as colistin combined therapy in terms of clinical and microbiological responses in patients with ventilator associated pneumonia (VAP and also in patients with blood stream infections. Conclusion: Although there is no randomised controlled study yet, colistin monotherapy and colistin combined therapy are likely to achieve similar treatment responses rates. Heteroresistant strains can emerge in patients who receive colistin monotherapy
Vijayakumar, Saranya; Rajenderan, Sangeetha; Laishram, Shakti; Anandan, Shalini; Balaji, Veeraraghavan; Biswas, Indranil
Acinetobacter baumannii is a nosocomial pathogen involved in various infections ranging from minor soft-tissue infections to more severe infections such as ventilator-associated pneumonia and bacteremia. The severity and the type of infections depend on the genetic and phenotypic variations of the strains. In this study, we compared the extent of biofilm formation and motility displayed by 60 multidrug-resistant A. baumannii clinical strains isolated from blood and sputum samples from patients from Southern India. Our results showed that isolates from the sputum samples formed significantly more robust biofilm compared to the blood isolates. On the other hand, we observed that the blood isolates were more motile than the sputum isolates. To the best of our knowledge, this is the first study that systematically evaluated the correlation between these two phenotypic traits and the nature of the isolates. PMID:27252939
Potron, Anaïs; Poirel, Laurent; Nordmann, Patrice
Multidrug resistance is quite common among non-fermenting Gram-negative rods, in particular among clinically relevant species including Pseudomonas aeruginosa and Acinetobacter baumannii. These bacterial species, which are mainly nosocomial pathogens, possess a diversity of resistance mechanisms that may lead to multidrug or even pandrug resistance. Extended-spectrum β-lactamases (ESBLs) conferring resistance to broad-spectrum cephalosporins, carbapenemases conferring resistance to carbapenems, and 16S rRNA methylases conferring resistance to all clinically relevant aminoglycosides are the most important causes of concern. Concomitant resistance to fluoroquinolones, polymyxins (colistin) and tigecycline may lead to pandrug resistance. The most important mechanisms of resistance in P. aeruginosa and A. baumannii and their most recent dissemination worldwide are detailed here. PMID:25857949
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.
Khalid Ahmed Al-Anazi
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
Doan, Tan N; Kong, David C M; Marshall, Caroline; Kirkpatrick, Carl M J; McBryde, Emma S
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 the organism
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
Full Text Available Background: Antibiotics such as fluoroquinolones are used for treating infections caused by Gram-negative bacteria, including Acinetobacter baumannii strains some time have extended-spectrum β-lactamase (ESBL, but ESBL production is rather rare. Resistance to fluoroquinolones antibiotics is mediated by lactamases and other mechanisms of resistance. The aim of the present study was to investigate of the prevalence of ESBL production and clonal relatedness of A. baumannii in Iran. Materials and Methods: A. baumannii isolates identified from patients at hospitals in Kermanshah, Iran, were studied. The double disk method was used for detection of ESBL production. The susceptibility to different antibiotics was determined by the disk diffusion method (CLSI. Clonal relatedness was determined by pulsed-field gel electrophoresis (PFGE and processed by Bionumerics 7.0 software. Statistical analyses were performed using SPSS-16.0. Results: This study showed high prevalence of resistance to ampicillin and cefpodoxim (98.1 and 92.3%. Fifty-two of the 84 isolates were identified as ESBL producers. Only colistin and tigecycline remained active against all isolates tested. The PFGE identified eight distinct pulsotypes: A (N=9, B (N=10, C (N=2, D (N=5, E (N=9, F (N=15, G (N=1 and H (N=1. The PFGE profiles A, B and F were believed to be endemic (specially clone F that was dominant across different wards of the hospitals and appeared to be endemic in the ICU, emergency, pediatric and infection area throughout the years. Conclusion: Early and timely detection of ESBL-producing A. baumannii clones is useful for preventing their spread within the hospital. PFGE analysis is helpful for detection of common strains in different wards and prevention of further spread of these pulsotypes to other hospital environment.
Demirdal, Tuna; Sari, Ummu Sena; Nemli, Salih Atakan
Background In the present study, our objective was to evaluate and compare the clinical and microbiological results in patients receiving systemic and systemic plus inhaled colistin therapy due to nosocomial pneumonia (NP) or ventilator associated pneumonia (VAP) caused by Acinetobacter baumannii. Methods A retrospective matched case–control study was performed at the ICUs at Izmir Katip Celebi University Ataturk Training and Research Hospital from January 2013 to December 2014. Eighty patien...
Aim: The in vitro activity of colistin in combination with sulbactam, netilmicin, and vancomycin against colistin-resistant A. baumannii strains was investigated. Furthermore, the clonal relationship of the strains was analyzed. Methods: Clonal relationship was investigated using rep-PCR. To screen for synergysm, the fractional inhibitory concentration index (FICI) was calculated using checkerboard assay. The killing kinetics of the combination of colistin with vancomycin was assessed using t...
Erika Coppo; Pier Andrea Dusi; Monica Dotta; Eugenio A. Debbia; Anna Marchese
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 perfor...
Percin, D; Akyol, S; Kalin, G
Aim: The in vitro activity of colistin in combination with sulbactam, netilmicin, and vancomycin against colistin-resistant A. baumannii strains was investigated. Furthermore, the clonal relationship of the strains was analyzed. Methods: Clonal relationship was investigated using rep-PCR. To screen for synergysm, the fractional inhibitory concentration index (FICI) was calculated using checkerboard assay. The killing kinetics of the combination of colistin with vancomycin was assessed usin...
López-Rojas, Rafael; Domínguez-Herrera, Juan; McConnell, Michael J.; Docobo-Pérez, Fernando; Smani, Younes; Fernández-Reyes, María; Rivas, Luis; Pachón, Jerónimo
Acinetobacter baumannii (American Type Culture Collection strain 19606) acquires mutations in the pmrB gene during the in vitro development of resistance to colistin. The colistin-resistant strain has lower affinity for colistin, reduced in vivo fitness (competition index, .016), and decreased virulence, both in terms of mortality (0% lethal dose, 6.9 vs 4.9 log colony-forming units) and survival in a mouse model of peritoneal sepsis. These results may explain the low incidence and disseminat...
Hasan, Tarik; Choi, Chul Hee; Oh, Man Hwan
Pathogenic bacteria survive in iron-limited host environments by using several iron acquisition mechanisms. Acinetobacter baumannii, causing serious infections in compromised patients, produces an iron-chelating molecule, called acinetobactin, which is composed of equimolar quantities of 2,3-dihydroxybenzoic acid (DHBA), L-threonine, and N-hydroxyhistamine, to compete with host cells for iron. Genes that are involved in the production and transport of acinetobactin are clustered within the ge...
Powers, Rachel A.; Swanson, Hollister C.; Taracila, Magdalena A.; Florek, Nicholas W.; Romagnoli, Chiara; Caselli, Emilia; Prati, Fabio; Bonomo, Robert A.; Wallar, Bradley J.
β-Lactam resistance in Acinetobacter baumannii presents one of the greatest challenges to contemporary antimicrobial chemotherapy. Much of this resistance to cephalosporins derives from the expression of the class C β-lactamase enzymes, known as Acinetobacter-derived cephalosporinases (ADCs). Currently, β-lactamase inhibitors are structurally similar to β-lactam substrates and are not effective inactivators of this class C cephalosporinase. Herein, two boronic acid transition state inhibitors...
zahra eFarshadzadeh; Farhad Bonakdar Hashemi; Sara eRahimi; Babak ePourakbari; Davoud eEsmaeili; Mohammad Ali Haghighi; Ali eMajidpour; Saeed eShojaa; Maryam eRahmani; Samira eGharesi; Masoud eAziemzadeh; Abbas eBahador
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 and multiplex PCR were perform...
Farshadzadeh, Zahra; Farhad B. Hashemi; Rahimi, Sara; Pourakbari, Babak; Esmaeili, Davoud; Haghighi, Mohammad A.; Majidpour, Ali; Shojaa, Saeed; Rahmani, Maryam; Gharesi, Samira; Aziemzadeh, Masoud; BAHADOR, Abbas
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...
Aynur Camkıran; Aycan Kundakcı; Coşkun Araz; Arash Pirat; Pınar Zeyneloğlu; Hande Arslan; Gülnaz Arslan
Objective: Multidrug resistant Acinetobacter baumannii (MRAB) is an important cause of hospital acquired infection and leads to an increasing morbidity and mortality in intensive care units (ICU). The aim of this study was to investigate the predictors of MRAB infection in surgical ICU patients. Material and Method: The charts of the patients who were admitted to the ICU between January 2008 and August 2010 were reviewed to identify patients with MRAB infection. Recorded data were as fo...
Leite, Gleice Cristina; Oliveira, Maura Salaroli; Perdigão-Neto, Lauro Vieira; Rocha, Cristiana Kamia Dias; Guimarães, Thais; Rizek, Camila; Levin, Anna Sara; Costa, Silvia Figueiredo
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. PMID:26998609
Full Text Available Background and Objectives: Multidrug-resistant Acinetobacter baumannii (MDR-Ab reported worldwide has become one of the most difficult nosocomially acquired Gram-negative pathogens to control and treat. The clinical utility of carbapenems is under threat with the emergence of acquired carbapenemases, particularly Ambler class B metallo-lactamases (MBL. Because of the global increase in the occurrence and dissemination of MBLs, early detection is critical. This study was undertaken to detect resistance to carbapenems in clinical isolates of A. baumannii from hospitalized patients by both disk-diffusion and minimum inhibitory concentration (MIC methods and to assess the rate of carbapenemase and MBL production among the isolates. Materials and Methods : A. baumannii were identified from various clinical samples and antibiotic susceptibility profile was determined by the standard disk-diffusion method. Meropenem-resistant strains were tested further by agar dilution MIC for meropenem. Resistant isolates were screened for carbapenemase production by the modified Hodge test and positive isolates were further checked for metallo-β-lacatmase production by the EDTA disk synergy test. Results : 42 isolates (31.81% showed resistance to meropenem by the disk diffusion method. 47.6% were carbapenemase positive by the modified Hodge test and 19% were MBL producers phenotypically by the EDTA disc synergy test (EDS. These meropenem-resistant isolates were resistant to most of the other antibiotics tested. These 42 isolates were recovered mostly from patients admitted to intensive care units. Four isolates of the A. baumannii complex were pan drug resistant and showed resistance to even tigecycline and polymyxin B. Conclusion : Carbapenem resistance has been increasingly reported, necessitating their detection. This study reports simple, carbapenemase, and MBL detection method that can be easily incorporated into the daily routine of a clinical laboratory.
Nassima Djahmi; Catherine Dunyach-Remy; Alix Pantel; Mazouz Dekhil; Albert Sotto; Jean-Philippe Lavigne
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 treat...
Karah, Nabil; Samuelsen, Ørjan; Zarrilli, Raffaele; Sahl, Jason W; Wai, Sun Nyunt; Uhlin, Bernt Eric
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. PMID:25706932
Full Text Available 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.
Goel, Vikas Kumar; Kapil, Arti
Background Iron is an important nutrient required by all forms of life.In the case of human hosts,the free iron availability is 10-18M,which is far less than what is needed for the survival of the invading bacterial pathogen.To survive in such conditions, bacteria express new proteins in their outer membrane and also secrete iron chelators called siderophores. Results/ Discussion Acinetobacter baumannii ATCC 19606, a nosocomial pathogen which grows under iron restricted conditions, expresses ...
Potron, Anaïs; Poirel , Laurent; Nordmann, Patrice
Multidrug resistance is quite common among non-fermenting Gram-negative rods, in particular among clinically relevant species including Pseudomonas aeruginosa and Acinetobacter baumannii. These bacterial species, which are mainly nosocomial pathogens, possess a diversity of resistance mechanisms that may lead to multidrug or even pandrug resistance. Extended-spectrum β-lactamases (ESBLs) conferring resistance to broad-spectrum cephalosporins, carbapenemases conferring resistance to carbapenem...
Golberg, Alexander; Broelsch, G. Felix; Vecchio, Daniela; Khan, Saiqa; Hamblin, Michael R.; Austen, William G.; Sheridan, Robert L.; Yarmush, Martin L.
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...
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.
Sevillano, Elena; Fernández, Elena; Bustamante, Zulema; Zabalaga, Silvia; Rosales, Ikerne; Umaran, Adelaida; Gallego, Lucía
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. PMID:21873380
Sutton, Kristin A; Breen, Jennifer; Russo, Thomas A; Schultz, L Wayne; Umland, Timothy C
The enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase catalyzes the sixth step of the seven-step shikimate pathway. Chorismate, the product of the pathway, is a precursor for the biosynthesis of aromatic amino acids, siderophores and metabolites such as folate, ubiquinone and vitamin K. The shikimate pathway is present in bacteria, fungi, algae, plants and apicomplexan parasites, but is absent in humans. The EPSP synthase enzyme produces 5-enolpyruvylshikimate 3-phosphate and phosphate from phosphoenolpyruvate and shikimate 3-phosphate via a transferase reaction, and is the target of the herbicide glyphosate. The Acinetobacter baumannii gene encoding EPSP synthase, aroA, has previously been demonstrated to be essential during host infection for the growth and survival of this clinically important drug-resistant ESKAPE pathogen. Prephenate dehydrogenase is also encoded by the bifunctional A. baumannii aroA gene, but its activity is dependent upon EPSP synthase since it operates downstream of the shikimate pathway. As part of an effort to evaluate new antimicrobial targets, recombinant A. baumannii EPSP (AbEPSP) synthase, comprising residues Ala301-Gln756 of the aroA gene product, was overexpressed in Escherichia coli, purified and crystallized. The crystal structure, determined to 2.37 Å resolution, is described in the context of a potential antimicrobial target and in comparison to EPSP synthases that are resistant or sensitive to the herbicide glyphosate. PMID:26919521
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.
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.
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.
Yassine Nait Chabane
Full Text Available The clinical importance of Acinetobacter baumannii is partly due to its natural ability to survive in the hospital environment. This persistence may be explained by its capacity to form biofilms and, interestingly, A. baumannii can form pellicles at the air-liquid interface more readily than other less pathogenic Acinetobacter species. Pellicles from twenty-six strains were morphologically classified into three groups: I egg-shaped (27%; II ball-shaped (50%; and III irregular pellicles (23%. One strain representative of each group was further analysed by Brewster's Angle Microscopy to follow pellicle development, demonstrating that their formation did not require anchoring to a solid surface. Total carbohydrate analysis of the matrix showed three main components: Glucose, GlcNAc and Kdo. Dispersin B, an enzyme that hydrolyzes poly-N-acetylglucosamine (PNAG polysaccharide, inhibited A. baumannii pellicle formation, suggesting that this exopolysaccharide contributes to pellicle formation. Also associated with the pellicle matrix were three subunits of pili assembled by chaperon-usher systems: the major CsuA/B, A1S_1510 (presented 45% of identity with the main pilin F17-A from enterotoxigenic Escherichia coli pili and A1S_2091. The presence of both PNAG polysaccharide and pili systems in matrix of pellicles might contribute to the virulence of this emerging pathogen.
Nait Chabane, Yassine; Marti, Sara; Rihouey, Christophe; Alexandre, Stéphane; Hardouin, Julie; Lesouhaitier, Olivier; Vila, Jordi; Kaplan, Jeffrey B; Jouenne, Thierry; Dé, Emmanuelle
The clinical importance of Acinetobacter baumannii is partly due to its natural ability to survive in the hospital environment. This persistence may be explained by its capacity to form biofilms and, interestingly, A. baumannii can form pellicles at the air-liquid interface more readily than other less pathogenic Acinetobacter species. Pellicles from twenty-six strains were morphologically classified into three groups: I) egg-shaped (27%); II) ball-shaped (50%); and III) irregular pellicles (23%). One strain representative of each group was further analysed by Brewster's Angle Microscopy to follow pellicle development, demonstrating that their formation did not require anchoring to a solid surface. Total carbohydrate analysis of the matrix showed three main components: Glucose, GlcNAc and Kdo. Dispersin B, an enzyme that hydrolyzes poly-N-acetylglucosamine (PNAG) polysaccharide, inhibited A. baumannii pellicle formation, suggesting that this exopolysaccharide contributes to pellicle formation. Also associated with the pellicle matrix were three subunits of pili assembled by chaperon-usher systems: the major CsuA/B, A1S_1510 (presented 45% of identity with the main pilin F17-A from enterotoxigenic Escherichia coli pili) and A1S_2091. The presence of both PNAG polysaccharide and pili systems in matrix of pellicles might contribute to the virulence of this emerging pathogen. PMID:25360550
Chang, David; Garcia, Rebecca A; Akers, Kevin S; Mende, Katrin; Murray, Clinton K; Wenke, Joseph C; Sanchez, Carlos J
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(NO₃)₃, 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(NO₃)₃ 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. PMID:26999163
Abedini, A; Roumy, V; Mahieux, S; Gohari, A; Farimani, M M; Rivière, C; Samaillie, J; Sahpaz, S; Bailleul, F; Neut, C; Hennebelle, T
The antimicrobial activities of 44 methanolic extracts from different parts of Iranian indigenous plant species used in traditional medicines of Iran were tested against a panel of 35 pathogenic and multiresistant bacteria and 1 yeast. The antimicrobial efficacy was determined using Müller-Hinton agar in Petri dishes seeded by a multiple inoculator and minimal inhibition concentration (MIC) method. The 21 most active extracts (MIC < 0·3 mg ml(-1) for one or several micro-organisms) were submitted to a more refined measurement. The best antibacterial activity was obtained by 10 plants. Microdilution assays allowed to determinate the MIC and MBC of the 21 most active extracts. The lowest achieved MIC value was 78 μg ml(-1), with 4 extracts. This work confirms the antimicrobial activity of assayed plants and suggests further examination to identify the chemical structure of their antimicrobial compounds. Significance and impact of the study: This study describes the antimicrobial screening of Iranian plant extracts chosen according to traditional practice against 36 microbial strains, from reference culture collections or recent clinical isolates, and enables to select 4 candidates for further chemical characterization and biological assessment: Dorema ammoniacum, Ferula assa-foetida, Ferulago contracta (seeds) and Perovskia abrotanoides (aerial parts). This may be useful in the development of potential antimicrobial agents, from easily harvested and highly sustainable plant parts. Moreover, the weak extent of cross-resistance between plant extracts and antibiotics warrants further research and may promote a strategy based on less potent but time-trained products. PMID:24888993
Yuan, Thomas Cheng-Hsin; Keller, Bernd
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.
Akkapeddi, P.R.; Glenn, P.; Fuschetto, A.; Appert, Q.; Viswanathan, V.K.
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.
Mori, Johanna [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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.
Winokur, Robert Michael
Trinity is a large-scale piece of program music for a symphony orchestra expanded to include two electric guitars (doubling on acoustic guitar), piano (doubling on Fender Rhodes Electric Piano), electric bass guitar and drumset. The main philosophical impetus for this piece is the programmatic depiction (in the manner of a tone poem) of a concept which is based on and combines archetypal characters drawn primarily from literary sources. This dissertation is titled Trinity and uses the thesi...
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.
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.
Gao, Jing; Zhao, Xiaonan; Bao, Ying; Ma, Ruihua; Zhou, Yufa; Li, Xinxian; Chai, Tongjie; Cai, Yumei
The study was conducted to investigate drug resistance, OXA-type carbapenemases-encoding genes and genetic diversity in airborne Acinetobacter baumannii (A. baumannii) in burn wards. Airborne A. baumannii were collected in burn wards and their corridors using Andersen 6-stage air sampler from January to June 2011. The isolates susceptibility to 13 commonly used antibiotics was examined according to the CLSI guidelines; OXA-type carbapenemases-encoding genes and molecular diversity of isolates were analyzed, respectively. A total of 16 non-repetitive A. baumannii were isolated, with 10 strains having a resistance rate of greater than 50% against the 13 antibiotics. The resistance rate against ceftriaxone, cyclophosvnamide, ciprofloxacin, and imipenem was 93.75% (15/16), but no isolate observed to be resistant to cefoperazone/sulbactam. Resistance gene analyses showed that all 16 isolates carried OXA-51, and 15 isolates carried OXA-23 except No.15; but OXA-24 and OXA-58 resistance genes not detected. The isolates were classified into 13 genotypes (A-M) according to repetitive extragenic palindromic sequence PCR (REP-PCR) results and only six isolates had a homology ≥90%. In conclusion, airborne A. baumannii in the burn wards had multidrug resistance and complex molecular diversity, and OXA-23 and OXA-51 were dominant mechanisms for resisting carbapenems. PMID:23886986
de Campos, Paola Amaral; Royer, Sabrina; da Fonseca Batistão, Deivid William; Araújo, Bruna Fuga; Queiroz, Lícia Ludendorff; de Brito, Cristiane Silveira; Gontijo-Filho, Paulo P; Ribas, Rosineide Marques
The emergence of Acinetobacter baumannii and Klebsiella pneumoniae strains in the hospital environment has been associated with the presence of multiple genetic elements, virulence factors and the ability to form biofilms. This study evaluated the biofilm formation ability of clinical and environmental A. baumannii and K. pneumoniae strains, isolated from various sources and presenting different molecular characteristics, resistance profiles and pulsed-field gel electrophoresis patterns. Fifty-three isolates were recovered from 2009 to 2014 in a Brazilian university hospital. Investigation of biofilm formation was performed for 10 strains of each species assessed by an initial adhesion assay, biofilm cell concentration and biofilm biomass, evaluated by quantitative assays in replicates, in three independent experiments. All strains of A. baumannii were able to attach to polystyrene plates, although two strains adhered to a lesser degree than the control. K. pneumoniae strains showed opposite behaviour, where only three strains adhered significantly when compared to the control. Quantitative evaluation revealed that in five A. baumannii and four K. pneumoniae isolates the biomass production could be characterised as moderate. None of the isolates were strong biofilm producers. Our results demonstrate: (1) biofilm formation is a heterogeneous property amongst A. baumannii and K. pneumoniae clinical strains and it was not associated with certain clonal types; (2) no relationship between multidrug resistance and biofilm production was observed; (3) more virulent K. pneumoniae strains tended to present higher production of biofilm. PMID:26846651
Full Text Available Acinetobacter baumannii is a strictly aerobic bacterium which causes severe infections, however its pathogenic characteristics are not well defined. Thirteen A. baumannii strains isolated from urine of hospitalized and nonhospitalized patients with different ages were investigated for the presence of virulence factors. The isolates belonged to biotypes 2, 6, and 9 and were sensitive to imipenem. The majority of them showed resistance to amikacin, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, norfloxacin, and trimethoprim-sulfamethoxazole. None of A. baumannii strains presented genes codifying for 17 different virulence factors previously described in uropathogenic Escherichia coli, when tested by polymerase chain reaction (PCR. Nine isolates agglutinated human group AB erythrocytes, in presence of mannose, but none of them agglutinated group O erythrocytes. Adherence to polystyrene was observed in 7 isolates, and this result did not correlate with that obtained in hemagglutination assay. All the isolates were able to grow in iron-limiting conditions, showing that A. baumannii produces some type of siderophore. However, the genes iutA and fyuA, from iron uptake system of E. coli and Yersinia sp., respectively, were not present in the isolates, suggesting the presence of a different type of siderophore. The fimbriae of A. baumannii strains that mediates the adherence are possibly mannose-resistant, eventhough the mechanism of adherence to human epithelial cells still remains to be elucidated.
Safari, Marzieh; Mozaffari Nejad, Amir Sasan; Bahador, Abas; Jafari, Rasool; Alikhani, Mohammad Yousef
The aim of this study was to investigate the prevalence of ESBL and MBL encoding genes among A. baumannii isolates. In this cross sectional study, 100 A. baumannii strains were isolated from ICU wards of 3 educational hospitals of Hamadan City, Iran in 2011. Phenotypic identification of the production of ESBLs and MBLs has been carried out by using E-test and DDST methods, respectively. PCR technique was used for amplification of the ESBL and MBL encoding genes, namely: CTX-M, SHV, TEM, OXA-51, VIM-Family, IMP-Family, SPM-1, SIM-1, and GIM-1. Eighty seven (87%), 95 (95%), 98 (98%) and 95 (95%) out of 100 A. baumannii isolates were resistant to imipenem, meropenem, ceftazidime and cefotaxime, respectively. Also, 99% and 7% of the isolates were MBLs and ESBLs produced phenotypically. Thirty (30%), 20 (20%) and 58 (58%) out of 100 A. baumannii isolates have been confirmed to harbor the bla VIM-family, TEM and SHV genes, respectively. Our results show no significant relationship between the detected gens with production of MBLs and ESBLs in spite of high prevalence of MBL encoding and drug resistant A. baumannii. Probably some other genes rather than what we studied are involved in phenotypic production of MBLs and ESBLs and subsequent drug resistance in Hamadan area, Iran. PMID:26150748
Antibacterial activity of the essential oil of Origanum vulgare L. (Lamiaceae against bacterial multiresistant strains isolated from nosocomial patients Atividade antibacteriana do óleo essencial de Origanum vulgare L. (Lamiaceae contra bactérias multiressistentes isoladas de pacientes nosocomial
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.Os antibióticos permanecem como a principal opção terapêutica para tratar infecções bacterianas, no entanto, existe a desvantagem de aumentarem a resistência bacteriana, e como alternativa, destaca-se a pesquisa de antimicrobianos de origem vegetal. Neste trabalho objetivou-se determinar in vitro a atividade antibacteriana do óleo essencial de Origanum vulgare L. (Lamiaceae (orégano, sobre bactérias multirresistentes isoladas de materiais biológicos. Foram usadas 24 linhagens de bactérias de origem hospitalar, divididas em seis espécies distintas, que foram inibidas pelo óleo essencial no "screening
Nickel biosorption by Acinetobacter baumannii and Pseudomonas aeruginosa isolated from industrial wastewater Bioadsorção de niquel por Acinetobacter baumannii e Pseudomonas aeruginosa isoladas de águas residuais industriais
Carlos E. Rodríguez
Full Text Available Nickel biosorption ability was evaluated in two bacterial strains: Acinetobacter baumannii UCR-2971 and Pseudomonas aeruginosa UCR-2957, resulting in greatest adsorption at pH 4.5 and a residence time of 100 minutes. Biosorption isotherms showed that the process follows the Langmuir model. The maximum adsorption rates (Nmax were 8.8 and 5.7 mg·g-1 for A. baumannii and P. aeruginosa, respectively; however, affinity constants suggest that P. aeruginosa (K=1.28 has higher affinity for nickel than A. baumannii (K=0.68. It is suggested that both strains could be used for wastewater treatment, as long as the concentration of Ni2+ is within the range of mg·L-1.Foi avaliada a capacidade de adsorção do Ni2+ por duas bactérias, Acinetobacter baumannii e Pseudomonas aeruginosa, em pH 4.5 com tempo de contato de 100 minutos. Isotermas de adsorção foram calculadas com as duas linhagens. Observou-se que, para ambas, o processo de adsorção está de acordo com o modelo fisicoquímico de Langmuir. A captação máxima do Ni2+ (Nmax foi 5.7 e 8.8 mg Ni2+ g-1 para P. aeruginosa e A. baumannii, respectivamente. Não obstante, P. aeruginosa apresenta uma constante de afinidade (K=1.28 maior que A. baumannii (K=0.68. Estes resultados indicam que ambas as linhagens são adequadas para o tratamento de águas contaminadas, desde que a concentração de níquel seja da ordem de mg·L-1.
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.
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
Blanco-Lobo, P; González-Galán, V; García-Quintanilla, M; Valencia, R; Cazalla, A; Martín, C; Alonso, I; Pérez-Romero, P; Cisneros, J M; Aznar, J; McConnell, M J
Real-time polymerase chain reaction (PCR)-based approaches have not been assessed in terms of their ability to detect patients colonized by Acinetobacter baumannii during active surveillance. This prospective, double-blind study demonstrated that a real-time PCR assay had high sensitivity (100%) and specificity (91.2%) compared with conventional culture for detecting A. baumannii in 397 active surveillance samples, and provided results within 3h. Receiver-operator curve analyses demonstrated that the technique has diagnostic accuracy of 97.7% (95% confidence interval 96.0-99.3%). This method could facilitate the rapid implementation of infection control measures for preventing the transmission of A. baumannii. PMID:27206968
Chen, Yan; Wu, Liyan; Chen, Yu; Xu, Zhijun; Xu, Liqun
Acinetobacter baumannii has emerged worldwide as an important opportunistic nosocomial pathogen and has become a major public health concern. In this study, the draft genome sequence of A. baumannii TCM331 (ST208/CC92), a multidrug-resistant (MDR) isolate harbouring the blaOXA-23 gene isolated in China, was determined. The genome of TCM331 was sequenced via Illumina HiSeq™ 2000, and bioinformatics analysis was performed. Important antimicrobial resistance determinants were observed in an estimated genome size of 4,058,691bp with 3838 predicted coding regions. In conclusion, these data might facilitate further understanding of the specific genomic features of MDR A. baumannii in China. PMID:27436391
Full Text Available Background and Aims: Given choice, bacteria prefer a community-based, surface-bound colony to an individual existence. The inclination for bacteria to become surface bound is so ubiquitous in diverse ecosystems that it suggests a strong survival strategy and selective advantage for surface dwellers over their free-ranging counterparts. Virtually any surface, biotic or abiotic (animal, mineral, or vegetable is suitable for bacterial colonization and bioﬁlm formation. Thus, a biofilm is "a functional consortium of microorganisms organized within an extensive exopolymeric matrix." Materials and Methods: The present study was undertaken to detect biofilm production from the repertoire stocks of Acinetobacter baumannii (A. baumannii and Pseudomonas aeruginosa (P. aeruginosa obtained from clinical specimens. The tube method was performed to qualitatively detect biofilm production. Results: A total of 109 isolates of both organisms were included in the study, out of which 42% (46/109 isolates showed biofilm detection. Among the biofilm producers, 57% of P. aeruginosa and 73% of A. baumannii showed multidrug resistance (MDR pattern which was statistically significant in comparison to nonbiofilm producers (P < 0.001. Conclusion: To the best of our knowledge, this is the only study to have tested the biofilm production in both P. aeruginosa and A. baumannii in a single study. Biofilm production and MDR pattern were found to be significantly higher in A. baumannii than P. aeruginosa. Antibiotic resistance was significantly higher among biofilm producing P. aeruginosa than non producers. Similarly, antibiotic resistance was significantly higher among biofilm producing A. baumannii than non producers.
Higuchi, Saito; Onodera, Yoshikuni; Chiba, Megumi; Hoshino, Kazuki; Gotoh, Naomasa
We investigated the in vitro activity of DS-8587, a novel fluoroquinolone, against Acinetobacter baumannii. The MICs of DS-8587 against clinical isolates and its inhibitory activity against target enzymes were superior to those of ciprofloxacin and levofloxacin. Furthermore, the antibacterial activity of DS-8587 was less affected by adeA/adeB/adeC or abeM efflux pumps than was that of ciprofloxacin and the frequency of single-step mutations with DS-8587 was lower than that with ciprofloxacin. DS-8587 might be an effective agent against A. baumannii infection. PMID:23380726
LIU, YONGRUI; LIU, XIANGQUN
The aim of the present study was to determine the prevalence and related drug resistance of AmpC β-lactamases in Acinetobacter baumannii in tertiary-level hospitals in the Xuzhou region in China. A total of 134 clinical isolates of non-repetitive Acinetobacter baumannii were collected from different hospitals in the Xuzhou region, and multiplex polymerase chain reaction (PCR) was employed to determine the genotype of AmpC. The PCR products were purified and sequenced. The susceptibility to an...
Ying, Chunmei; Li, Yongli; Wang, Yaping; Zheng, Bing; Yang, Chengde
The objective of this work was to investigate correlations between Acinetobacter baumannii isolates from neurosurgical intensive care unit patients and its environment. This is a prospective, observational study. The minimal inhibitory concentrations of antimicrobial agents against 27 clinical and 28 environmental isolates were determined by the agar dilution method. Molecular genotyping was performed by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR), pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The presence of carbapenemase and metallo-β-lactamase genes were analyzed by specific PCRs and DNA sequencing. From the clinical A. baumannii isolates, 25.9% were found resistant to minocycline, 51.9% to cefoperazone-sulbactam, 59.3% to imipenem and 70% resistant to other antimicrobial agents. Environmental isolates were more sensitive compared with clinical isolates (P<0.05). Twenty-seven clinical isolates comprised three ERIC-PCR genotypes, four major PFGE pulsotypes and five distinct MLST sequence types (STs) (ST208, ST368, ST191, ST195, ST540), all belonging to CC92 with only one locus (gpi) difference among them. Twenty-eight environmental isolates showed more diverse genetic types than clinical isolates and comprised six ERIC-PCR groups, nine PFGE groups and two main STs (ST208, ST229). Four clinical and 15 environmental isolates could not be identified by MLST and were assigned to non-clonal STs. We identified the presence of the blaOXA-23 carbapenemase encoding gene in most of the clinical (21/27) but fewer in the environmental isolates (3/28). The A. baumannii strains isolated from patients were genetically similar to the environmental strains, with CC92 members as the major fraction but with different antibiotic susceptibilities. PMID:25873322
Dai, Tianhong; Tegos, George P.; Lu, Zongshun; Zhiyentayev, Timur; Huang, Liyi; Franklin, Michael J.; Baer, David G.; Hamblin, Michael R.
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.
Full Text Available Aim – In recent years, the incidence of nosocomial infections due to A.baumannii has increased to a point of concern. Rapid spread of multidrug and extremely drug resistant A.baumannii in clinical settings has made treatment options difficult for clinician. It has also in creased the morbidity and mortality in immunocompromised patients. The aim of this study was to investigate the ef ficacy of essential oil of a traditional medicinal plant, Cymbopogon flexuosus (lemon grass against the problematic multidrug resistant A.baumannii . Methodology – Essential oil of lemon grass was distilled by Neo-Clav enger’s method and the antibacterial activity was tested against 102 multidrug resistant A.baumannii clinical isolates by punch-well and disc diffusion methods. The minimum inhibitory concentration of lemon grass oil was determined by Macrobroth dilution method. Results – Majority of A.baumannii isolates were inhibited by lemon grass oil, inhibition zone ranging from 13mm to 33mm, mean inhibition zone being 23mm and the minimum inhib itory concentration of lemon grass oil was 6.25μl/ml. Conclusion – essential oil lemon grass showed good antibacterial activity against A.baumannii and might be considered as an alternative treatment option against multi-drug resistant A.baumannii infections. However, further pharmacokinetic and pharmacodynamic studies are needed for routine clinical use.
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.
Hadeel K. Musafer
Full Text Available Collecting samples of Acinetobacter baumannii taken from different clinical cases of wounds, septicemia, and urinary tract infections. That was accomplished by taking (296 samples from Baghdad educational hospital and Ibn-al-Baladi hospital. Samples were cultured on solid media (McConkey and blood agars, and according to microscopical, cultural, and biochemical identification, in addition to using API 20-E system, (21 isolates of A. baumannii were identified and in percentage of 47.619, 9.523, 14.285, and 28.571 for wound, blood, sputum, and urine samples, respectively. Methods: detection of fimbriated bacterial isolates among 21 isolates, and all those isolated were fimbriae forming isolates; isolate number (9 was selected as an effective isolate in formation of fimbriae. Non-forming fimbriae isolate of Shigella flexneri is used as negative control. Results and Conclusion: the average of adherence of fimbriated bacterial cell with human epithelial cells was reached (50 adherent bacterial cell per epithelial cell compared with the average of adherence of control isolate (12 adherent bacterial cell per epithelial cell, the inhibition processes are performed: Inhibition of bacterial adherence by specific antibodies of fimbriae antigen showed inhibition effect of adherence in respect to fimbriated isolate A. baumannii 9 also the subminimum inhibitory concentration for four antibiotics (Gentamicin, Tobramycin, Cefepime, and Amikacin inhibit the adherence of fimbriated isolate. The isolates (used in the study have the ability to agglutinate Saccharomyces cerevisiae and human red blood corpuscles (RBCs. The study of effect of different fimbriae extract concentrations (25, 50, 100 μg/ml on immune cells; consequently, reached to the following results: Concentrations of (25, 50, 100 μg/ml showed a negative effect on lymphocyte and PMNs viability which increased significantly (P≤0.05 with increasing of fimbriae extract concentration. On the other hand
Gáfaro Montejo, Alexis
Se analizaron 129 aislamientos de Acinetobacter baumannii obtenidos de hospitales colombianos de tercer nivel con el objetivo de detectar y caracterizar integrones de tipo I (elementos genéticos importantes por la capacidad de adquirir determinantes genéticos de resistencia a los antibióticos) y su relación con el fenotipo de resistencia antibiótica. De los aislamientos estudiados el 24% fueron positivos para la presencia del integrón de tipo I. La caracterización de estos últimos demostró...
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)
Bassett, B A [Institute of Cosmology and Gravitation, University of Portsmouth (United Kingdom)
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
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, .
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
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...
Japoni-Nejad, Alireza; Farshad, Shohreh; van Belkum, Alex; Ghaznavi-Rad, Ehsanollah
Antibiotic resistance in Acinetobacter baumannii is a major problem in the hospital and outbreaks caused by this organism have been reported frequently. The present study aimed at determining the antibiotic susceptibility patterns, the prevalence of different classes of integrons and the characterization of integron class 1 gene cassettes in Iranian A. baumannii isolates. A total of 63 non-duplicate A. baumannii isolates were collected from clinical and environmental specimens in the Vali-Asr hospital in the central province of Iran (March to September, 2011). The antimicrobial susceptibility for 15 antibiotics which are used conventionally was determined by disk diffusion. The presence of different integron classes was investigated by PCR and the size of gene cassettes in class 1 integrons was then determined by PCR as well. Moreover, integron cassette arrays of isolates were delineated by RFLP and sequencing amplicons with different lengths. Of 63 isolates 62 (98.4%) carried a class 1 integron. The prevalence of IntI2 was 15.9% and the length of the amplicons ranged from 500 bp to 3 kb. Sequencing of integrons of class 1 revealed the presence of many resistance genes (aadA, aacA, aacC, dfrA, bla(GES) and bla(IMP)). We identified a completely new gene cassette which contained aacA7-qacF-aadA5-bla(IMP), this cassette has not been reported previously in A. baumannii. PMID:24161711
Denise von Dolinger de Brito
Full Text Available We studied an outbreak of two multi-drug resistant clones of Acinetobacter baumannii in the Neonatal Intensive Care Unit of the Uberlândia Federal University Hospital in Minas Gerais state, Brazil, and we analyzed the contribution of cross-transmission in the rise in infection rates. Eleven neonates who developed multi-drug resistant A. baumannii nosocomial infection were matched to 22 neonates who were admitted to the same unit and did not develop an infection during the outbreak period, in order to identify risk factors for infection. Three out of the 11 neonates died. Epidemiological investigation included molecular typing, using pulsed field gel electrophoresis. Prior to the outbreak, from December 2001 to March 2002, no case of infection by this microorganism was diagnosed. Environmental and healthcare worker hand cultures were negative. Nine isolates had similar pulsed field gel electrophoresis patterns and two had another clone. The first clone was brought into the unit by an infected patient who was transferred from another hospital without a history of antibiotic use. The second clone did have its origin clearly defined. Both infected groups led us to conclude that several factors contributed to infection with A. baumannii. These factors were: exposure to antibiotics and invasive devices, birth weight 7 days. Based on logistic regression, infected neonates were more exposed to carbapenem and mechanical ventilation than the control group. Cross transmission between infants contributed to the rise in the rates of multi-drug resistant A. baumannii infection.
Liu, Xu; Yin, Hong; Weng, Chun-Xiao; Cai, Yun
Acinetobacter baumannii biofilms in catheters are very difficult to treat. Low-frequency ultrasound (LFU) may improve bactericidal or bacteriostatic activity. However, no previous studies have been reported on its efficacy against pan-resistant biofilms of A. baumannii. This study was designed to investigate whether LFU can enhance the activity of colistin, vancomycin and colistin-vancomycin combinations against pan-resistant biofilms of A. baumannii. The efficacy of colistin combinations was determined using the fractional inhibitory concentration index (FICI). The antibacterial effect was determined from bacteria counts in biofilms and the establishment of 24-h time-kill curves. A significantly synergistic effect was detected between colistin and vancomycin (FICI colistin in the combination treatments resulted in a better ultrasound-enhanced antibacterial effect. In 24-h time-kill curves, the combination of colistin (8 μg/mL) plus vancomycin (4 μg/mL) with LFU caused a significant reduction in bacteria counts in biofilms after 8 h and a continuing decline until 24 h. Bacterial counts were reduced by 3.77 log(CFU/mL) by LFU plus combinations, compared with combinations without LFU at 24 h. Our results indicate that LFU in combination with colistin plus vancomycin may be useful in treating pan-resistant A. baumannii infections. PMID:27131840
Full Text Available Multidrug resistant A. baumannii has emerged as an important and problematic human pathogen as it is the causative agent of several types of infections especially in neonates and immunocompromised patients because they have least capacity to fight against infections. Carbapenems are used as last resort antibiotics for treating these infections but currently resistance against carbapenems due to MBL production is on the rise. The objective of this study was to determine the frequency of antibiotic resistance in A. baumannii and also to compare the efficacy of combined disk test and double disk synergy test for detection of metallo-beta-lactamases. A total of 112 A. baumannii were identified from various clinical samples and antibiotic susceptibility profile was determined by Kirby-Bauer Disk Diffusion method. Out of 112, 66 (58.9% isolates were resistant to both imipenem and meropenem (OXOID. These resistant isolates were tested for carbapenemase production, and 55 (83.3% were carbapenemase producers by Modified Hodge Test. These isolates were further tested for MBL production by combined disk test and double disk synergy test. Out of 66, 49 isolates were positive by both methods, CDT and DDST, and only one isolate was detected as negative (with kappa value = 0.038. All MBL producing strains showed remarkable resistance to cephalosporins, fluoroquinolones, aminoglycosides, and piperacillin/tazobactam (OXOID. The antibiotic resistance was very high in A. baumannii which were isolated from children in Pakistan specially attending a nephrology unit.
Anwar, Muneeza; Ejaz, Hassan; Zafar, Aizza; Hamid, Hamdan
Multidrug resistant A. baumannii has emerged as an important and problematic human pathogen as it is the causative agent of several types of infections especially in neonates and immunocompromised patients because they have least capacity to fight against infections. Carbapenems are used as last resort antibiotics for treating these infections but currently resistance against carbapenems due to MBL production is on the rise. The objective of this study was to determine the frequency of antibiotic resistance in A. baumannii and also to compare the efficacy of combined disk test and double disk synergy test for detection of metallo-beta-lactamases. A total of 112 A. baumannii were identified from various clinical samples and antibiotic susceptibility profile was determined by Kirby-Bauer Disk Diffusion method. Out of 112, 66 (58.9%) isolates were resistant to both imipenem and meropenem (OXOID). These resistant isolates were tested for carbapenemase production, and 55 (83.3%) were carbapenemase producers by Modified Hodge Test. These isolates were further tested for MBL production by combined disk test and double disk synergy test. Out of 66, 49 isolates were positive by both methods, CDT and DDST, and only one isolate was detected as negative (with kappa value = 0.038). All MBL producing strains showed remarkable resistance to cephalosporins, fluoroquinolones, aminoglycosides, and piperacillin/tazobactam (OXOID). The antibiotic resistance was very high in A. baumannii which were isolated from children in Pakistan specially attending a nephrology unit. PMID:27123345
Full Text Available Difficulties involved in treating drug-resistant pathogens have created a need for new therapies. In this study, we investigated the possibility of using oleanolic acid (OA, a natural pentacyclic triterpenoid, as a natural adjuvant for antibiotics against Acinetobacter baumannii. High concentrations of OA can kill cells, partly because it generates reactive oxygen species. Measurement of the fractional inhibitory concentration (FIC for OA and time-kill experiments demonstrated that it only synergizes with aminoglycoside antibiotics (e.g., gentamicin, kanamycin. Other classes of antibiotics (e.g., ampicillin, rifampicin, norfloxacin, chloramphenicol, and tetracycline have no interactions with OA. Microarray and quantitative reverse transcription-PCR analysis indicated that genes involved in ATP synthesis and cell membrane permeability, the gene encoding glycosyltransferase, peptidoglycan-related genes, phage-related genes, and DNA repair genes were upregulated under OA. OA highly induces the expression of adk, which encodes an adenylate kinase, and des6, which encodes a linoleoyl-CoA desaturase, and deletion of these genes increased FICs; these observations indicate that adk and des6 are involved in the synergism of OA with aminoglycosides. Data obtained using 8-anilino-1-naphthalenesulfonic acid, fluorescence-conjugated gentamicin, and membrane fatty acid analysis indicates that adk and des6 are involved in changes in membrane permeability. Proton-motive force and ATP synthesis tests show that those genes are also involved in energy metabolism. Taken together, our data show that OA boosts aminoglycoside uptake by changing membrane permeability and energy metabolism in A. baumannii.
Full Text Available 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 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 blaOXA-23-like (88% and blaPER-1 (54% were detected. ISAba1 was detected upstream of blaADC, blaOXA-23-like and blaOXA51-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 6 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