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Sample records for intestinal gram-negative bacteria

  1. The role of intestinal colonization with gram-negative bacteria as a source for intensive care unit-acquired bacteremia

    NARCIS (Netherlands)

    Oostdijk, E.A.; Smet, A.M. de; Kesecioglu, J.; Bonten, M.J.; Kalkman, C.J.; Joore, H.C.; Hoeven, J.G. van der; Pickkers, P.; Sturm, P.D.J.; Voss, A.; et al.,

    2011-01-01

    OBJECTIVE: Selective digestive tract decontamination aims to eradicate gram-negative bacteria in both the intestinal tract and respiratory tract and is combined with a 4-day course of intravenous cefotaxime. Selective oropharyngeal decontamination only aims to eradicate respiratory tract

  2. Quorum sensing in gram-negative bacteria

    DEFF Research Database (Denmark)

    Wu, H.; Song, Z.J.; Høiby, N.

    2004-01-01

    Bacteria can communicate with each other by means of signal molecules to coordinate the behavior of the entire community, and the mechanism is referred to as quorum sensing (QS). Signal systems enable bacteria to sense the size of their densities by monitoring the concentration of the signal...... molecules. Among Gram-negative bacteria N-acyl-L-homoserine lactone (acyl-HSL)-dependent quorum sensing systems are particularly widespread. These systems are used to coordinate expression of phenotypes that are fundamental to the interaction of bacteria with each other and with their environment...

  3. Antimicrobial resistance of gram-negative aerobic bacteria isolates ...

    African Journals Online (AJOL)

    The increasing incidence of antimicrobial resistance in pathogenic and commensal Gram-negative bacteria from dogs has continued to raise concerns in veterinary small animal practice and public health. In this study, antimicrobial resistance was investigated in Gram-negative aerobic bacteria isolated from the faeces of ...

  4. Volatile metabolites from some gram-negative bacteria

    DEFF Research Database (Denmark)

    Schöller, Charlotte; Molin, Søren; Wilkins, Ken

    1997-01-01

    A survey of volatile organic compounds (VOCs) excreted from various Gram-negative bacteria (Pseudomonas spp., Serratia spp. and Enterobacter spp.) was carried out. Compounds were identified by gas chromatography-mass spectrometry. VOCs identified included dimethyl disulphide, dimethyl trisulphide...

  5. Silver enhances antibiotic activity against gram-negative bacteria.

    Science.gov (United States)

    Morones-Ramirez, J Ruben; Winkler, Jonathan A; Spina, Catherine S; Collins, James J

    2013-06-19

    A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive-specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.

  6. Differential effect of immune cells on non-pathogenic Gram-negative bacteria-induced nuclear factor-kappaB activation and pro-inflammatory gene expression in intestinal epithelial cells

    DEFF Research Database (Denmark)

    Haller, D.; Holt, L.; Parlesak, Alexandr

    2004-01-01

    We have previously shown that non-pathogenic Gram negative bacteria induce RelA phosphorylation, nuclear factor (NF)-kappaB transcriptional activity and pro-inflammatory gene expression in intestinal epithelial cells (IEC) in vivo and in vitro. In this study, we investigated the molecular mechanism......, PBMC from patients with active ulcerative colitis and Crohn's disease differentially trigger epithelial cell activation in response to E. coli and E. coli-derived LPS. In conclusion, this study provides evidence for a differential regulation of non-pathogenic Gram-negative bacteria-induced NF......-kappaB signalling and IL-8 gene expression in IEC cocultured with immune cells and suggests the presence of mechanisms that assure hyporesponsiveness of the intestinal epithelium to certain commensally enteric bacteria....

  7. Insights into Newer Antimicrobial Agents against Gram-negative Bacteria

    Directory of Open Access Journals (Sweden)

    Neelam Yaneja

    2016-01-01

    Full Text Available Currently, drug resistance, especially against cephalosporins and carbapenems, among gram-negative bacteria is an important challenge, which is further enhanced by the limited availability of drugs against these bugs. There are certain antibiotics (colistin, fosfomycin, temocillin, and rifampicin that have been revived from the past to tackle the menace of superbugs, including members of Enterobacteriaceae, Acinetobacter species, and Pseudomonas species. Very few newer antibiotics have been added to the pool of existing drugs. There are still many antibiotics that are passing through various phases of clinical trials. The initiative of Infectious Disease Society of America to develop 10 novel antibiotics against gram-negative bacilli by 2020 is a step to fill the gap of limited availability of drugs. This review aims to provide insights into the current and newer drugs in pipeline for the treatment of gram-negative bacteria and also discusses the major challenging issues for their management.

  8. NDM 1 Gene Carrying Gram negative Bacteria Isolated from Rats ...

    African Journals Online (AJOL)

    In this study, we screened 56 Gram negative bacteria comprising: 3 isolates of Enterobacter ludwigii, 30 Pseudomonas aeruginosa, 22 Proteus mirabilis, and 1 Aeromonas caviae isolated from oral cavity and rectum of rats captured from commercial poultry houses in Ibadan, Oyo State, Nigeria that were resistant to at least ...

  9. Low prevalence of antibiotic-resistant gram-negative bacteria ...

    African Journals Online (AJOL)

    The objective of this study was to determine antibiotic resistance patterns and specific resistance genes in Gram-negative enteric bacteria recovered from 42 different drinking water sources servicing 2 rural villages in south-western Uganda. These water sites were prone to contamination by both human and cattle activity.

  10. Mechanisms of Antimicrobial Peptide Resistance in Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Victor I. Band

    2014-12-01

    Full Text Available Cationic antimicrobial peptides (CAMPs are important innate immune defenses that inhibit colonization by pathogens and contribute to clearance of infections. Gram-negative bacterial pathogens are a major target, yet many of them have evolved mechanisms to resist these antimicrobials. These resistance mechanisms can be critical contributors to bacterial virulence and are often crucial for survival within the host. Here, we summarize methods used by Gram-negative bacteria to resist CAMPs. Understanding these mechanisms may lead to new therapeutic strategies against pathogens with extensive CAMP resistance.

  11. Multidrug efflux systems in Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Maria Aparecida Scatamburlo Moreira

    2004-06-01

    Full Text Available Multidrug efflux mechanisms in bacteria contribute significantly to intrinsic and acquired resistance to antimicrobial agents. Genome analysis have confirmed the broad distribution of these systems in Gram-negative as well as in Gram-positive bacteria. Among resistance mechanisms, the multidrug efflux system or pump deserves special attention, since a cell that has acquired it can simultaneously diminish or even suppress the susceptibility to a wide range of antimicrobials. The efflux system is mediated by transport proteins which confer resistance to toxic compounds. In Gram-negative bacteria, a tripartite efflux system is necessary to expel the drug to the outer medium: a protein localized in the cytoplasmic membrane; another in the periplasmatic space (membrane fusion protein - MFP; and a third in the outer membrane (outer membrane factor - OMF. The drug transport is active, and depends either on the energy provided by ATP hydrolysis or is directly driven by the proton motive force. The transport proteins are grouped in families, according to the homology of the amino acid sequences and to similarity of mechanisms. Among Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa have most of the hitherto identified and studied multidrug efflux systems.

  12. Extended-spectrum ß-lactamases in gram negative bacteria

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    Deepti Rawat

    2010-01-01

    Full Text Available Extended-spectrum ß-lactamases (ESBLs are a group of plasmid-mediated, diverse, complex and rapidly evolving enzymes that are posing a major therapeutic challenge today in the treatment of hospitalized and community-based patients. Infections due to ESBL producers range from uncomplicated urinary tract infections to life-threatening sepsis. Derived from the older TEM is derived from Temoniera, a patient from whom the strain was first isolated in Greece. ß-lactamases, these enzymes share the ability to hydrolyze third-generation cephalosporins and aztreonam and yet are inhibited by clavulanic acid. In addition, ESBL-producing organisms exhibit co-resistance to many other classes of antibiotics, resulting in limitation of therapeutic option. Because of inoculum effect and substrate specificity, their detection is also a major challenge. At present, however, organizations such as the Clinical and Laboratory Standards Institute (formerly the National Committee for Clinical Laboratory Standards provide guidelines for the detection of ESBLs in Klebsiella pneumoniae, K. oxytoca, Escherichia coli and Proteus mirabilis. In common to all ESBL-detection methods is the general principle that the activity of extended-spectrum cephalosporins against ESBL-producing organisms will be enhanced by the presence of clavulanic acid. Carbapenems are the treatment of choice for serious infections due to ESBL-producing organisms, yet carbapenem-resistant isolates have recently been reported. ESBLs represent an impressive example of the ability of gram-negative bacteria to develop new antibiotic-resistance mechanisms in the face of the introduction of new antimicrobial agents. Thus there is need for efficient infection-control practices for containment of outbreaks; and intervention strategies, e.g., antibiotic rotation to reduce further selection and spread of these increasingly resistant pathogens.

  13. Prediction of lipoprotein signal peptides in Gram-negative bacteria

    DEFF Research Database (Denmark)

    Juncker, Agnieszka; Willenbrock, Hanni; Von Heijne, G.

    2003-01-01

    A method to predict lipoprotein signal peptides in Gram-negative Eubacteria, LipoP, has been developed. The hidden Markov model (HMM) was able to distinguish between lipoproteins (SPaseII-cleaved proteins), SPaseI-cleaved proteins, cytoplasmic proteins, and transmembrane proteins. This predictor...... was able to predict 96.8% of the lipoproteins correctly with only 0.3% false positives in a set of SPaseI-cleaved, cytoplasmic, and transmembrane proteins. The results obtained were significantly better than those of previously developed methods. Even though Gram-positive lipoprotein signal peptides differ...... from Gram-negatives, the HMM was able to identify 92.9% of the lipoproteins included in a Gram-positive test set. A genome search was carried out for 12 Gram-negative genomes and one Gram-positive genome. The results for Escherichia coli K12 were compared with new experimental data, and the predictions...

  14. Predatory bacteria: a potential ally against multidrug-resistant Gram-negative pathogens.

    Directory of Open Access Journals (Sweden)

    Daniel E Kadouri

    Full Text Available Multidrug-resistant (MDR Gram-negative bacteria have emerged as a serious threat to human and animal health. Bdellovibrio spp. and Micavibrio spp. are Gram-negative bacteria that prey on other Gram-negative bacteria. In this study, the ability of Bdellovibrio bacteriovorus and Micavibrio aeruginosavorus to prey on MDR Gram-negative clinical strains was examined. Although the potential use of predatory bacteria to attack MDR pathogens has been suggested, the data supporting these claims is lacking. By conducting predation experiments we have established that predatory bacteria have the capacity to attack clinical strains of a variety of ß-lactamase-producing, MDR Gram-negative bacteria. Our observations indicate that predatory bacteria maintained their ability to prey on MDR bacteria regardless of their antimicrobial resistance, hence, might be used as therapeutic agents where other antimicrobial drugs fail.

  15. Resistance trends in gram-negative bacteria: surveillance results from two Mexican hospitals, 2005–2010

    Directory of Open Access Journals (Sweden)

    Morfin-Otero Rayo

    2012-06-01

    Full Text Available Abstract Background Hospital-acquired infections caused by multiresistant gram-negative bacteria are difficult to treat and cause high rates of morbidity and mortality. The analysis of antimicrobial resistance trends of gram-negative pathogens isolated from hospital-acquired infections is important for the development of antimicrobial stewardship programs. The information obtained from antimicrobial resistant programs from two hospitals from Mexico will be helpful in the selection of empiric therapy for hospital-acquired gram-negative infections. Findings Two thousand one hundred thirty two gram-negative bacteria collected between January 2005 and December 2010 from hospital-acquired infections occurring in two teaching hospitals in Mexico were evaluated. Escherichia coli was the most frequently isolated gram-negative bacteria, with >50% of strains resistant to ciprofloxacin and levofloxacin. Klebsiella spp. showed resistance rates similar to Escherichia coli for ceftazidime (33.1% vs 33.2%, but exhibited lower rates for levofloxacin (18.2% vs 56%. Of the samples collected for the third most common gram-negative bacteria, Pseudomonas aeruginosa, >12.8% were resistant to the carbapenems, imipenem and meropenem. The highest overall resistance was found in Acinetobacter spp. Enterobacter spp. showed high susceptibility to carbapenems. Conclusions E. coli was the most common nosocomial gram-negative bacilli isolated in this study and was found to have the second-highest resistance to fluoroquinolones (>57.9%, after Acinetobacter spp. 81.2%. This finding represents a disturbing development in a common nosocomial and community pathogen.

  16. Widespread Fosfomycin Resistance in Gram-Negative Bacteria Attributable to the Chromosomal fosA Gene

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    Ryota Ito

    2017-08-01

    Full Text Available Fosfomycin is a decades-old antibiotic which is being revisited because of its perceived activity against many extensively drug-resistant Gram-negative pathogens. FosA proteins are Mn2+ and K+-dependent glutathione S-transferases which confer fosfomycin resistance in Gram-negative bacteria by conjugation of glutathione to the antibiotic. Plasmid-borne fosA variants have been reported in fosfomycin-resistant Escherichia coli strains. However, the prevalence and distribution of fosA in other Gram-negative bacteria are not known. We systematically surveyed the presence of fosA in Gram-negative bacteria in over 18,000 published genomes from 18 Gram-negative species and investigated their contribution to fosfomycin resistance. We show that FosA homologues are present in the majority of genomes in some species (e.g., Klebsiella spp., Enterobacter spp., Serratia marcescens, and Pseudomonas aeruginosa, whereas they are largely absent in others (e.g., E. coli, Acinetobacter baumannii, and Burkholderia cepacia. FosA proteins in different bacterial pathogens are highly divergent, but key amino acid residues in the active site are conserved. Chromosomal fosA genes conferred high-level fosfomycin resistance when expressed in E. coli, and deletion of chromosomal fosA in S. marcescens eliminated fosfomycin resistance. Our results indicate that FosA is encoded by clinically relevant Gram-negative species and contributes to intrinsic fosfomycin resistance.

  17. STUDY ON SURGICAL SITE INFECTIONS CAUSED BY ESBL PRODUCING GRAM NEGATIVE BACTERIA

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    Rambabu

    2015-09-01

    Full Text Available Surgical site infections have been a major problem, because of the emergence of drug resistant bacteria, in particular B - lactamase producing bacteria. Extended spectrum beta lactamase producing gram negative organisms pose a great challenge in treatment o f SSI present study is aimed at determining multiple drug resistance in gram negative bacteria & to find out ESBL producers, in correlation with treatment outcome. A total of 120 wound infected cases were studied. Staphylococcus aureus was predominant bact erium - 20.Among gram negative bacteria, Pseudomonas species is predominant (14 followed by Escherichia coli (13 , Klebsiella species (12 , Proteus (9 Citrobacter (4 Providencia (2 & Acinetobacter species (2 . Out of 56 gramnegative bacteria isolated, 20 were i dentified as ESBL producers, which was statistically significant. Delay in wound healing correlated with infection by ESBL producers, which alarms the need of abstinence from antibiotic abuse

  18. Prevalence of AmpC β-lactamase among Gram-negative bacteria ...

    African Journals Online (AJOL)

    Purpose: Infections caused by AmpC-positive bacteria results in high patient morbidity and mortality making their detection clinically important as they cannot be detected in routine susceptibility testing. This study aim to determine the prevalence of AmpC β-lactamase among Gram negative bacteria recovered from clinical ...

  19. [Antimicrobial therapy in severe infections with multidrug-resistant Gram-negative bacterias].

    Science.gov (United States)

    Duszyńska, Wiesława

    2010-01-01

    Multidrug-resistant Gram-negative bacteria pose a serious and rapidly emerging threat to patients in healthcare settings, and are especially prevalent and problematic in intensive therapy units. Recently, the emergence of pandrug-resistance in Gram-negative bacteria poses additional concerns. This review examines the clinical impact and epidemiology of multidrug-resistant Gram-negative bacteria as a cause of increased morbidity and mortality among ITU patients. Beta-lactamases, cephalosporinases and carbapenemases play the most important role in resistance to antibiotics. Despite the tendency to increased resistance, carbapenems administered by continuous infusion remain the most effective drugs in severe sepsis. Drug concentration monitoring, albeit rarely used in practice, is necessary to ensure an effective therapeutic effect.

  20. The antibiotic pipeline for multi-drug resistant gram negative bacteria: what can we expect?

    Science.gov (United States)

    Falagas, Matthew E; Mavroudis, Andreas D; Vardakas, Konstantinos Z

    2016-08-01

    A real concern in the medical community is the increasing resistance of bacteria, especially that of Gram-negative types. New antibiotics are currently under clinical development, promising to tackle severe infections caused, especially, by multi-drug resistant (MDR) bacteria and broaden the armamentarium of clinicians. We searched PUBMED and GOOGLE databases. Combinations of already approved β-lactams or monobactams with new β-lactamase inhibitors [imipenem-cilastatin/MK-7655 (relebactam), meropenem/RPX7009 (vaborbactam), ceftaroline/avibactam, aztreonam/avibactam], new β-lactams (S-649266, BAL30072), aminoglycosides (plazomicin), quinolones (finafloxacin) and tetracyclines (eravacycline) were included in the review. Expert commentary: For the majority of the upcoming antibiotics the currently available data is limited to their microbiology and pharmacokinetics. Their effectiveness and safety against infections due to MDR bacteria remain to be proved. Significant issues are also the impact of these antibiotics on the human intestinal microbiota and their possible co-administration with already-known antimicrobial agents in difficult-to-treat-infections; further studies should be conducted for these objectives.

  1. Loss of outer membrane integrity in Gram-negative bacteria by silver ...

    Indian Academy of Sciences (India)

    Mater. Sci., Vol. 39, No. 7, December 2016, pp. 1871–1878. c Indian Academy of Sciences. DOI 10.1007/s12034-016-1317-5. Loss of outer membrane integrity in Gram-negative bacteria by silver nanoparticles loaded with Camellia sinensis leaf phytochemicals: plausible mechanism of bacterial cell disintegration. M SINGH.

  2. Protamine-induced permeabilization of cell envelopes of gram-positive and gram-negative bacteria

    DEFF Research Database (Denmark)

    Johansen, Charlotte; Verheul, A.; Gram, Lone

    1997-01-01

    carboxyfluorescein and ATP after 2 to 5 min. Maximum antibacterial activity was reached at alkaline pH and in the absence of divalent cations. The efficient permeabilization of cell envelopes of both gram-positive and gram-negative bacteria suggests that protamine causes a general disruption of the cell envelope...

  3. The structures of lipopolysaccharides from plant-associated gram-negative bacteria

    DEFF Research Database (Denmark)

    Molinaro, Antonio; Newman, Mari-Anne; Lanzetta, Rosa

    2009-01-01

    Gram-negative bacterial lipopolysaccharides (LPSs) have multiple roles in plant-microbe interactions. LPSs contribute to the low permeabilities of bacterial outer membranes, which act as barriers to protect bacteria from plant-derived antimicrobial substances. Conversely, perception of LPSs by pl...

  4. Antibacterial activities of β-glucan (laminaran) against gram-negative and gram-positive bacteria

    Science.gov (United States)

    Chamidah, A.; Hardoko, Prihanto, A. A.

    2017-05-01

    This study aimed to determine the antibacterial activity of β-Glucan (laminaran) of LAE and LME extracts from brown algae Sargassum crassifolium using HPMS and Ultrasonication against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Salmonella typhimurium and Escherichia coli). The highest antibacterial activities of LME extract obtained using the HPMS method against Gram-positive bacteria (B. subtilis and S. aureus) were at 18:10 and 18.80 mm. The ultrasonication method showed a lower inhibition trend than the HPMS method, with MIC and MBC values of 250 mg/ml and 2-8 CFU/ml, respectively, in all Gram-negative and Gram-positive bacteria. The results showed that LME extract at a concentration of 250 mg/mL is bacteriostatic against Gram-positive and -negative bacteria.

  5. Quorum-Sensing Signal-Response Systems in Gram-Negative Bacteria

    Science.gov (United States)

    Papenfort, Kai; Bassler, Bonnie

    2016-01-01

    Abstract / Preface Bacteria use quorum sensing to orchestrate gene expression programmes that underlie collective behaviours. Quorum sensing relies on the production, release, detection and group-level response to extracellular signalling molecules, which are called autoinducers. Recent work has discovered new autoinducers in Gram-negative bacteria, shown how these molecules are recognized by cognate receptors, revealed new regulatory components that are embedded in canonical signalling circuits and identified novel regulatory network designs. In this Review we examine how, together, these features of quorum sensing signal–response systems combine to control collective behaviours in Gram-negative bacteria and we discuss the implications for host–microbial associations and antibacterial therapy. PMID:27510864

  6. Nanotransformation of Vancomycin Overcomes the Intrinsic Resistance of Gram-Negative Bacteria.

    Science.gov (United States)

    Fernandes, Margarida M; Ivanova, Kristina; Hoyo, Javier; Pérez-Rafael, Sílvia; Francesko, Antonio; Tzanov, Tzanko

    2017-05-03

    The increased emergence of antibiotic-resistant bacteria is a growing public health concern, and although new drugs are constantly being sought, the pace of development is slow compared with the evolution and spread of multidrug-resistant species. In this study, we developed a novel broad-spectrum antimicrobial agent by simply transforming vancomycin into nanoform using sonochemistry. Vancomycin is a glycopeptide antibiotic largely used for the treatment of infections caused by Gram-positive bacteria but inefficient against Gram-negative species. The nanospherization extended its effect toward Gram-negative Escherichia coli and Pseudomonas aeruginosa, making these bacteria up to 10 and 100 times more sensitive to the antibiotic, respectively. The spheres were able to disrupt the outer membranes of these bacteria, overcoming their intrinsic resistance toward glycopeptides. The penetration of nanospheres into a Langmuir monolayer of bacterial membrane phospholipids confirmed the interaction of the nanoantibiotic with the membrane of E. coli cells, affecting their physical integrity, as further visualized by scanning electron microscopy. Such mechanism of antibacterial action is unlikely to induce mutations in the evolutionary conserved bacterial membrane, therefore reducing the possibility of acquiring resistance. Our results indicated that the nanotransformation of vancomycin could overcome the inherent resistance of Gram-negative bacteria toward this antibiotic and disrupt mature biofilms at antibacterial-effective concentrations.

  7. Exogenous lytic activity of SPN9CC endolysin against gram-negative bacteria.

    Science.gov (United States)

    Lim, Jeong-A; Shin, Hakdong; Heu, Sunggi; Ryu, Sangryeol

    2014-06-28

    Concerns over drug-resistant bacteria have stimulated interest in developing alternative methods to control bacterial infections. Endolysin, a phage-encoded enzyme that breaks down bacterial peptidoglycan at the terminal stage of the phage reproduction cycle, is reported to be effective for the control of bacterial pathogenic bacteria. Bioinformatic analysis of the SPN9CC bacteriophage genome revealed a gene that encodes an endolysin with a domain structure similar to those of the endolysins produced by the P1 and P22 coliphages. The SPN9CC endolysin was purified with a C-terminal oligo-histidine tag. The endolysin was relatively stable and active over a broad temperature range (from 24°C to 65°C). It showed maximal activity at 50°C, and its optimum pH range was from pH 7.5 to 8.5. The SPN9CC endolysin showed antimicrobial activity against only gram-negative bacteria and functioned by cutting the glycosidic bond of peptidoglycan. Interestingly, the SPN9CC endolysin could lyse intact gram-negative bacteria in the absence of EDTA as an outer membrane permeabilizer. The exogenous lytic activity of the SPN9CC endolysin makes it a potential therapeutic agent against gram-negative bacteria.

  8. PVC bacteria: variation of, but not exception to, the Gram-negative cell plan.

    Science.gov (United States)

    Devos, Damien P

    2014-01-01

    Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) bacteria have features that differentiate them from classical Gram-negative (G-) bacteria. One such feature is their complex endomembrane system. Based on the difference of membrane organization and compartment identity, PVC bacteria were proposed to form an exception to the bacterial G- cell plan. Here I argue that all PVC membranes are derived from G- membranes, and that their organization and the compartments they form are similar to those of G- bacteria. I suggest that PVC membrane organization should be evaluated within a G- framework and as a variation of it. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Identification and Determination of Antibiotic Multiresistance of Gram-negative Bacteria Isolated from Hospital Sewage

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    Fatih Matyar

    2016-10-01

    Full Text Available In this study it was aimed to determine the microbial diversity and level of antibiotic resistance patterns of Gram-negative bacterial isolates from the hospital sewages. The 219 Gram-negative bacterial isolates to 16 different antibiotics (belonging 10 classes, was investigated by agar diffusion method. A total of 18 species of bacteria were isolated: the most common strains isolated from all samples were Klebsiella oxytoca (27.4%, Klebsiella pneumoniae (20.5% and Escherichia coli (20.1%. There was a high incidence of resistance to ampicillin (98.6%, streptomycin (95.9% and erythromycin (90.0%, and a low incidence of resistance to cefepim (13.2%, imipenem (5.0% and meropenem (3.2%. 35.6% of all bacteria isolated from hospital sewage were resistant to 9 different antibiotics. The multiple antibiotic resistances (MAR index ranged from 0.25 to 0.94. Results show that hospital sewages have a significant proportion of antibiotic resistant Gram-negative bacteria, and these bacteria constitute a potential risk for public health.

  10. Lipopolysaccharide biogenesis and transport at the outer membrane of Gram-negative bacteria.

    Science.gov (United States)

    Sperandeo, Paola; Martorana, Alessandra M; Polissi, Alessandra

    2017-11-01

    The outer membrane (OM) of Gram-negative bacteria is an asymmetric lipid bilayer containing a unique glycolipid, lipopolysaccharide (LPS) in its outer leaflet. LPS molecules confer to the OM peculiar permeability barrier properties enabling Gram-negative bacteria to exclude many toxic compounds, including clinically useful antibiotics, and to survive harsh environments. Transport of LPS poses several problems to the cells due to the amphipatic nature of this molecule. In this review we summarize the current knowledge on the LPS transport machinery, discuss the challenges associated with this process and present the solutions that bacterial cells have evolved to address the problem of LPS transport and assembly at the cell surface. Finally, we discuss how knowledge on LPS biogenesis can be translated for the development of novel antimicrobial therapies. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016. Published by Elsevier B.V.

  11. Antimicrobial compounds targeting Gram-negative bacteria in food: Their mode of action and combinational effects

    DEFF Research Database (Denmark)

    Hyldgaard, Morten

    2015-01-01

    they interact with bacterial cells to exert their mechanism of inhibition or killing. Furthermore, natural antimicrobials are often not potent enough as single compounds, and may cause unwanted sensory side-effects, which limit the quantities that can be applied to food. These problems might be circumvented......Gram-negative bacteria are a major cause of food spoilage and foodborne illnesses. However, finding effective solutions against Gram-negative bacteria are complicated because of increasing consumer demands for more natural, minimally processed, and fresh high quality food products without...... that isoeugenol permeabilized the cytoplasmic membrane, and probably inhibited intracellular esterases. We proposed that isoeugenol interacted with cytoplasmic membranes of E. coli in a reversible fashion, which destabilized membranes to become leaky in a non-disruptive detergent-like mechanism. In the third...

  12. Intrinsic, adaptive and acquired antimicrobial resistance in Gram-negative bacteria.

    Science.gov (United States)

    Arzanlou, Mohsen; Chai, Wern Chern; Venter, Henrietta

    2017-02-28

    Gram-negative bacteria are responsible for a large proportion of antimicrobial-resistant infections in humans and animals. Among this class of bacteria are also some of the most successful environmental organisms. Part of this success is their adaptability to a variety of different niches, their intrinsic resistance to antimicrobial drugs and their ability to rapidly acquire resistance mechanisms. These mechanisms of resistance are not exclusive and the interplay of several mechanisms causes high levels of resistance. In this review, we explore the molecular mechanisms underlying resistance in Gram-negative organisms and how these different mechanisms enable them to survive many different stress conditions. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  13. Membrane-active macromolecules kill antibiotic-tolerant bacteria and potentiate antibiotics towards Gram-negative bacteria.

    Directory of Open Access Journals (Sweden)

    Divakara S S M Uppu

    Full Text Available Chronic bacterial biofilms place a massive burden on healthcare due to the presence of antibiotic-tolerant dormant bacteria. Some of the conventional antibiotics such as erythromycin, vancomycin, linezolid, rifampicin etc. are inherently ineffective against Gram-negative bacteria, particularly in their biofilms. Here, we report membrane-active macromolecules that kill slow dividing stationary-phase and antibiotic tolerant cells of Gram-negative bacteria. More importantly, these molecules potentiate antibiotics (erythromycin and rifampicin to biofilms of Gram-negative bacteria. These molecules eliminate planktonic bacteria that are liberated after dispersion of biofilms (dispersed cells. The membrane-active mechanism of these molecules forms the key for potentiating the established antibiotics. Further, we demonstrate that the combination of macromolecules and antibiotics significantly reduces bacterial burden in mouse burn and surgical wound infection models caused by Acinetobacter baumannii and Carbapenemase producing Klebsiella pneumoniae (KPC clinical isolate respectively. Colistin, a well-known antibiotic targeting the lipopolysaccharide (LPS of Gram-negative bacteria fails to kill antibiotic tolerant cells and dispersed cells (from biofilms and bacteria develop resistance to it. On the contrary, these macromolecules prevent or delay the development of bacterial resistance to known antibiotics. Our findings emphasize the potential of targeting the bacterial membrane in antibiotic potentiation for disruption of biofilms and suggest a promising strategy towards developing therapies for topical treatment of Gram-negative infections.

  14. Membrane-active macromolecules kill antibiotic-tolerant bacteria and potentiate antibiotics towards Gram-negative bacteria.

    Science.gov (United States)

    Uppu, Divakara S S M; Konai, Mohini M; Sarkar, Paramita; Samaddar, Sandip; Fensterseifer, Isabel C M; Farias-Junior, Celio; Krishnamoorthy, Paramanandam; Shome, Bibek R; Franco, Octávio L; Haldar, Jayanta

    2017-01-01

    Chronic bacterial biofilms place a massive burden on healthcare due to the presence of antibiotic-tolerant dormant bacteria. Some of the conventional antibiotics such as erythromycin, vancomycin, linezolid, rifampicin etc. are inherently ineffective against Gram-negative bacteria, particularly in their biofilms. Here, we report membrane-active macromolecules that kill slow dividing stationary-phase and antibiotic tolerant cells of Gram-negative bacteria. More importantly, these molecules potentiate antibiotics (erythromycin and rifampicin) to biofilms of Gram-negative bacteria. These molecules eliminate planktonic bacteria that are liberated after dispersion of biofilms (dispersed cells). The membrane-active mechanism of these molecules forms the key for potentiating the established antibiotics. Further, we demonstrate that the combination of macromolecules and antibiotics significantly reduces bacterial burden in mouse burn and surgical wound infection models caused by Acinetobacter baumannii and Carbapenemase producing Klebsiella pneumoniae (KPC) clinical isolate respectively. Colistin, a well-known antibiotic targeting the lipopolysaccharide (LPS) of Gram-negative bacteria fails to kill antibiotic tolerant cells and dispersed cells (from biofilms) and bacteria develop resistance to it. On the contrary, these macromolecules prevent or delay the development of bacterial resistance to known antibiotics. Our findings emphasize the potential of targeting the bacterial membrane in antibiotic potentiation for disruption of biofilms and suggest a promising strategy towards developing therapies for topical treatment of Gram-negative infections.

  15. Survival of Gram-Negative Bacteria on Plastic Compounded with Hexachlorophene

    Science.gov (United States)

    Taylor, Gerald F.

    1970-01-01

    Gram-negative bacteria representing nine genera were screened for their ability to survive surface exposure to polyethylene sheet plastic containing chemically compounded hexachlorophene (0.25%). Subcultures were made at hourly intervals over a 6-hr period of time. An exceedingly large drop in viable cells beginning at the 1-hr exposure was noted for each genus except one tested on the hexachlorophene-plastic, whereas most nonadditive controls grew bacterial colonies too numerous to count. PMID:5415208

  16. Chromogenic method for rapid isolation of recA-like mutants of gram-negative bacteria.

    OpenAIRE

    Barbe, J; Fernandez de Henestrosa, A R; Calero, S; Gibert, I

    1991-01-01

    We have devised a rapid and widely applicable color test for detecting recA-like mutants of gram-negative bacteria. The technique depends on decreased expression of an Escherichia coli recA-lacZ fusion in recA mutants and uses a broad-host-range plasmid to transfer the fusion gene into new species. We describe the isolation of a recA-like mutant of Pseudomonas syringae by this technique.

  17. A New Family of Lysozyme Inhibitors Contributing to Lysozyme Tolerance in Gram-Negative Bacteria

    OpenAIRE

    Callewaert, Lien; Aertsen, Abram; Deckers, Daphne; Vanoirbeek, Kristof G. A.; Vanderkelen, Lise; Van Herreweghe, Joris M.; Masschalck, Barbara; Nakimbugwe, Dorothy; Robben, Johan; Michiels, Chris W.

    2008-01-01

    Lysozymes are ancient and important components of the innate immune system of animals that hydrolyze peptidoglycan, the major bacterial cell wall polymer. Bacteria engaging in commensal or pathogenic interactions with an animal host have evolved various strategies to evade this bactericidal enzyme, one recently proposed strategy being the production of lysozyme inhibitors. We here report the discovery of a novel family of bacterial lysozyme inhibitors with widespread homologs in gram-negative...

  18. Rationalizing the permeation of polar antibiotics into Gram-negative bacteria

    International Nuclear Information System (INIS)

    Scorciapino, Mariano Andrea; Acosta-Gutierrez, Silvia; Benkerrou, Dehbia; D’Agostino, Tommaso; Malloci, Giuliano; Samanta, Susruta; Bodrenko, Igor; Ceccarelli, Matteo

    2017-01-01

    The increasing level of antibiotic resistance in Gram-negative bacteria, together with the lack of new potential drug scaffolds in the pipeline, make the problem of infectious diseases a global challenge for modern medicine. The main reason that Gram-negative bacteria are particularly challenging is the presence of an outer cell-protecting membrane, which is not present in Gram-positive species. Such an asymmetric bilayer is a highly effective barrier for polar molecules. Several protein systems are expressed in the outer membrane to control the internal concentration of both nutrients and noxious species, in particular: (i) water-filled channels that modulate the permeation of polar molecules and ions according to concentration gradients, and (ii) efflux pumps to actively expel toxic compounds. Thus, besides expressing specific enzymes for drugs degradation, Gram-negative bacteria can also resist by modulating the influx and efflux of antibiotics, keeping the internal concentration low. However, there are no direct and robust experimental methods capable of measuring the permeability of small molecules, thus severely limiting our knowledge of the molecular mechanisms that ultimately control the permeation of antibiotics through the outer membrane. This is the innovation gap to be filled for Gram-negative bacteria. This review is focused on the permeation of small molecules through porins, considered the main path for the entry of polar antibiotics into Gram-negative bacteria. A fundamental understanding of how these proteins are able to filter small molecules is a prerequisite to design/optimize antibacterials with improved permeation. The level of sophistication of modern molecular modeling algorithms and the advances in new computer hardware has made the simulation of such complex processes possible at the molecular level. In this work we aim to share our experience and perspectives in the context of a multidisciplinary extended collaboration within the IMI

  19. Rationalizing the permeation of polar antibiotics into Gram-negative bacteria

    Science.gov (United States)

    Scorciapino, Mariano Andrea; Acosta-Gutierrez, Silvia; Benkerrou, Dehbia; D'Agostino, Tommaso; Malloci, Giuliano; Samanta, Susruta; Bodrenko, Igor; Ceccarelli, Matteo

    2017-03-01

    The increasing level of antibiotic resistance in Gram-negative bacteria, together with the lack of new potential drug scaffolds in the pipeline, make the problem of infectious diseases a global challenge for modern medicine. The main reason that Gram-negative bacteria are particularly challenging is the presence of an outer cell-protecting membrane, which is not present in Gram-positive species. Such an asymmetric bilayer is a highly effective barrier for polar molecules. Several protein systems are expressed in the outer membrane to control the internal concentration of both nutrients and noxious species, in particular: (i) water-filled channels that modulate the permeation of polar molecules and ions according to concentration gradients, and (ii) efflux pumps to actively expel toxic compounds. Thus, besides expressing specific enzymes for drugs degradation, Gram-negative bacteria can also resist by modulating the influx and efflux of antibiotics, keeping the internal concentration low. However, there are no direct and robust experimental methods capable of measuring the permeability of small molecules, thus severely limiting our knowledge of the molecular mechanisms that ultimately control the permeation of antibiotics through the outer membrane. This is the innovation gap to be filled for Gram-negative bacteria. This review is focused on the permeation of small molecules through porins, considered the main path for the entry of polar antibiotics into Gram-negative bacteria. A fundamental understanding of how these proteins are able to filter small molecules is a prerequisite to design/optimize antibacterials with improved permeation. The level of sophistication of modern molecular modeling algorithms and the advances in new computer hardware has made the simulation of such complex processes possible at the molecular level. In this work we aim to share our experience and perspectives in the context of a multidisciplinary extended collaboration within the IMI

  20. Emergence of Pan-drug resistance amongst gram negative bacteria! The First case series from India

    Directory of Open Access Journals (Sweden)

    Abdul Ghafur

    2014-09-01

    Full Text Available Objective: Increasing prevalence of carbapenem resistant Gram negative bacteria is a serious clinical and public health challenge. Bacteria resistant to all available antibiotics (Pan Drug Resistance herald the onset of post antibiotics era. We hereby report clinical profile of 13 patients with pan drug resistant gram negative isolates. Methods:Retrospective analysis of 13 patients with pan drug resistant gram negative isolates over the last 18 months was done by medical records review. Identification of the isolates and susceptibility testing was done using VITEK auto analyzer in concordance with the corresponding CLSI guidelines. Results:Out of four patients with bacteremic isolates, three patients received colistin based combination therapy. Though two of these patients had microbiologic clearance, all the three died. Out of the 9 patients with non bacteremic isolates, 4 had infection and 5 had colonization. Three (out of four were treated with combination therapy including colistin and one patient received colistin monotherapy. All four patients had microbiological clearance. Three patients had clinical cure and were discharged. One patient later developed bacteremia and died. Conclusion:Infections, particularly blood stream with pan drug resistant organisms has a higher mortality. Urgent studies to reevaluate existing therapeutic options and research into new antibiotic molecules are the need of the hour. J Microbiol Infect Dis 2014; 4(3: 86-91

  1. Gram positive and Gram negative bacteria differ in their sensitivity to cold plasma

    Science.gov (United States)

    Mai-Prochnow, Anne; Clauson, Maryse; Hong, Jungmi; Murphy, Anthony B.

    2016-12-01

    Cold atmospheric-pressure plasma (CAP) is a relatively new method being investigated for antimicrobial activity. However, the exact mode of action is still being explored. Here we report that CAP efficacy is directly correlated to bacterial cell wall thickness in several species. Biofilms of Gram positive Bacillus subtilis, possessing a 55.4 nm cell wall, showed the highest resistance to CAP, with less than one log10 reduction after 10 min treatment. In contrast, biofilms of Gram negative Pseudomonas aeruginosa, possessing only a 2.4 nm cell wall, were almost completely eradicated using the same treatment conditions. Planktonic cultures of Gram negative Pseudomonas libanensis also had a higher log10 reduction than Gram positive Staphylococcus epidermidis. Mixed species biofilms of P. aeruginosa and S. epidermidis showed a similar trend of Gram positive bacteria being more resistant to CAP treatment. However, when grown in co-culture, Gram negative P. aeruginosa was more resistant to CAP overall than as a mono-species biofilm. Emission spectra indicated OH and O, capable of structural cell wall bond breakage, were present in the plasma. This study indicates that cell wall thickness correlates with CAP inactivation times of bacteria, but cell membranes and biofilm matrix are also likely to play a role.

  2. O-antigen protects gram-negative bacteria from histone killing.

    Directory of Open Access Journals (Sweden)

    Catherine Chaput

    Full Text Available Beyond their traditional role of wrapping DNA, histones display antibacterial activity to Gram-negative and -positive bacteria. To identify bacterial components that allow survival to a histone challenge, we selected resistant bacteria from homologous Escherichia coli libraries that harbor plasmids carrying pieces of the chromosome in different sizes. We identified genes required for exopolysaccharide production and for the synthesis of the polysaccharide domain of the lipopolysaccharide, called O-antigen. Indeed, O-antigen and exopolysaccharide conferred further resistance to histones. Notably, O-antigen also conferred resistance to histones in the pathogens Shigella flexneri and Klebsiella pneumoniae.

  3. Mid-infrared spectroscopic assessment of nanotoxicity in gram-negative vs. gram-positive bacteria.

    Science.gov (United States)

    Heys, Kelly A; Riding, Matthew J; Strong, Rebecca J; Shore, Richard F; Pereira, M Glória; Jones, Kevin C; Semple, Kirk T; Martin, Francis L

    2014-03-07

    Nanoparticles appear to induce toxic effects through a variety of mechanisms including generation of reactive oxygen species (ROS), physical contact with the cell membrane and indirect catalysis due to remnants from manufacture. The development and subsequent increasing usage of nanomaterials has highlighted a growing need to characterize and assess the toxicity of nanoparticles, particularly those that may have detrimental health effects such as carbon-based nanomaterials (CBNs). Due to interactions of nanoparticles with some reagents, many traditional toxicity tests are unsuitable for use with CBNs. Infrared (IR) spectroscopy is a non-destructive, high throughput technique, which is unhindered by such problems. We explored the application of IR spectroscopy to investigate the effects of CBNs on Gram-negative (Pseudomonas fluorescens) and Gram-positive (Mycobacterium vanbaalenii PYR-1) bacteria. Two types of IR spectroscopy were compared: attenuated total reflection Fourier-transform infrared (ATR-FTIR) and synchrotron radiation-based FTIR (SR-FTIR) spectroscopy. This showed that Gram-positive and Gram-negative bacteria exhibit differing alterations when exposed to CBNs. Gram-positive bacteria appear more resistant to these agents and this may be due to the protection afforded by their more sturdy cell wall. Markers of exposure also vary according to Gram status; Amide II was consistently altered in Gram-negative bacteria and carbohydrate altered in Gram-positive bacteria. ATR-FTIR and SR-FTIR spectroscopy could both be applied to extract biochemical alterations induced by each CBN that were consistent across the two bacterial species; these may represent potential biomarkers of nanoparticle-induced alterations. Vibrational spectroscopy approaches may provide a novel means of fingerprinting the effects of CBNs in target cells.

  4. Combination antibiotic therapy for multidrug-resistant Gram-negative bacteria.

    Science.gov (United States)

    Tängdén, Thomas

    2014-05-01

    Combination antibiotic therapy for Gram-negative sepsis is controversial. The present review provides a brief summary of the existing knowledge on combination therapy for severe infections with multidrug-resistant Pseudomonas spp., Acinetobacter spp., and Enterobacteriaceae. Empirical combination antibiotic therapy is recommended for severe sepsis and septic shock to reduce mortality related to inappropriate antibiotic treatment. Because definitive combination therapy has not been proven superior to monotherapy in meta-analyses, it is generally advised to de-escalate antibiotic therapy when the antibiotic susceptibility profile is known, although it cannot be excluded that some subgroups of patients might still benefit from continued combination therapy. Definitive combination therapy is recommended for carbapenemase-producing Enterobacteriaceae and should also be considered for severe infections with Pseudomonas and Acinetobacter spp. when beta-lactams cannot be used. Because resistance to broad-spectrum beta-lactams is increasing in Gram-negative bacteria and because no new antibiotics are expected to become available in the near future, the antibacterial potential of combination therapy should be further explored. In vitro data suggest that combinations can be effective even if the bacteria are resistant to the individual antibiotics, although existing evidence is insufficient to support the choice of combinations and explain the synergistic effects observed. In vitro models can be used to screen for effective combinations that can later be validated in animal or clinical studies. Further, in the absence of clinical evidence, in vitro data might be useful in supporting therapeutic decisions for severe infections with multidrug-resistant Gram-negative bacteria.

  5. In Vitro Antibacterial Activity of Several Plant Extracts and Oils against Some Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Ayman Al-Mariri

    2014-01-01

    Full Text Available Background: Medicinal plants are considered new resources for producing agents that could act as alternatives to antibiotics in the treatment of antibiotic-resistant bacteria. The aim of this study was to evaluate the antibacterial activity of 28 plant extracts and oils against four Gram-negative bacterial species. Methods: Experimental, in vitro, evaluation of the activities of 28 plant extracts and oils as well as some antibiotics against E. coli O157:H7, Yersinia enterocolitica O9, Proteus spp., and Klebsiella pneumoniae was performed. The activity against 15 isolates of each bacterium was determined by disc diffusion method at a concentration of 5%. Microdilution susceptibility assay was used in order to determine the minimal inhibitory concentrations (MICs of the plant extracts, oils, and antibiotics. Results: Among the evaluated herbs, only Origanum syriacum L., Thymus syriacus Boiss., Syzygium aromaticum L., Juniperus foetidissima Wild, Allium sativum L., Myristica fragrans Houtt, and Cinnamomum zeylanicum L. essential oils and Laurus nobilis L. plant extract showed anti-bacterial activity. The MIC50 values of these products against the Gram-negative organisms varied from 1.5 (Proteus spp. and K. pneumoniae( and 6.25 µl/ml (Yersinia enterocolitica O9 to 12.5 µl/ml (E. coli O:157. Conclusion: Among the studied essential oils, O. syriacum L., T. syriacus Boiss., C. zeylanicum L., and S. aromaticum L. essential oils were the most effective. Moreover, Cephalosporin and Ciprofloxacin were the most effective antibiotics against almost all the studied bacteria. Therefore, O. syriacum L., T. syriacus Boiss., C. zeylanicum L., and S. aromaticum L. could act as bactericidal agents against Gram-negative bacteria.

  6. An inner membrane platform in the type II secretion machinery of Gram-negative bacteria

    OpenAIRE

    Py, Béatrice; Loiseau, Laurent; Barras, Frédéric

    2001-01-01

    The type II secretion machinery allows most Gram-negative bacteria to deliver virulence factors into their surroundings. We report that in Erwinia chrysanthemi, GspE (the putative NTPase), GspF, GspL and GspM constitute a complex in the inner membrane that is presumably used as a platform for assembling other parts of the secretion machinery. The GspE–GspF–GspL–GspM complex was demonstrated by two methods: (i) co-immunoprecipitation of GspE–GspF–GspL with antibodies raised against either GspE...

  7. Quorum sensing signal molecules (acylated homoserine lactones) in Gram-negative fish pathogenic bacteria

    DEFF Research Database (Denmark)

    Bruhn, Jesper Bartholin; Dalsgaard, Inger; Nielsen, K.F.

    2005-01-01

    The aim of the present study was to investigate the production of quorum sensing signals (specifically acylated homoserine lactones, AHLs) among a selection of strains of Gram-negative fish bacterial pathogens. These signals are involved in the regulation of virulence factors in some human....... In conclusion, the production of quorum sensing signals, AHLs, is common among the strains that we examined. If the AHL molecules regulate the expression of the virulence phenotype in these bacteria, as shown to occur in some bacterial pathogens, novel disease control measures may be developed by blocking AHL...

  8. Positive selection procedure for entrapment of insertion sequence elements in gram-negative bacteria.

    OpenAIRE

    Gay, P; Le Coq, D; Steinmetz, M; Berkelman, T; Kado, C I

    1985-01-01

    We constructed the broad-host-range plasmid pUCD800 containing the sacB gene of Bacillus subtilis for use in the positive selection and isolation of insertion sequence (IS) elements in gram-negative bacteria. Cells containing pUCD800 do not grow on medium containing 5% sucrose unless the sacB gene is inactivated. By using pUCD800, we isolated a 1.4-kilobase putative IS element from Agrobacterium tumefaciens NT1RE by selection for growth on sucrose medium. This putative IS element appears to b...

  9. An optimized staining technique for the detection of Gram positive and Gram negative bacteria within tissue.

    Science.gov (United States)

    Becerra, Sandra C; Roy, Daniel C; Sanchez, Carlos J; Christy, Robert J; Burmeister, David M

    2016-04-12

    Bacterial infections are a common clinical problem in both acute and chronic wounds. With growing concerns over antibiotic resistance, treatment of bacterial infections should only occur after positive diagnosis. Currently, diagnosis is delayed due to lengthy culturing methods which may also fail to identify the presence of bacteria. While newer costly bacterial identification methods are being explored, a simple and inexpensive diagnostic tool would aid in immediate and accurate treatments for bacterial infections. Histologically, hematoxylin and eosin (H&E) and Gram stains have been employed, but are far from optimal when analyzing tissue samples due to non-specific staining. The goal of the current study was to develop a modification of the Gram stain that enhances the contrast between bacteria and host tissue. A modified Gram stain was developed and tested as an alternative to Gram stain that improves the contrast between Gram positive bacteria, Gram negative bacteria and host tissue. Initially, clinically relevant strains of Pseudomonas aeruginosa and Staphylococcus aureus were visualized in vitro and in biopsies of infected, porcine burns using routine Gram stain, and immunohistochemistry techniques involving bacterial strain-specific fluorescent antibodies as validation tools. H&E and Gram stain of serial biopsy sections were then compared to a modification of the Gram stain incorporating a counterstain that highlights collagen found in tissue. The modified Gram stain clearly identified both Gram positive and Gram negative bacteria, and when compared to H&E or Gram stain alone provided excellent contrast between bacteria and non-viable burn eschar. Moreover, when applied to surgical biopsies from patients that underwent burn debridement this technique was able to clearly detect bacterial morphology within host tissue. We describe a modification of the Gram stain that provides improved contrast of Gram positive and Gram negative microorganisms within host

  10. Medicinal plant extracts with efflux inhibitory activity against Gram-negative bacteria.

    Science.gov (United States)

    Garvey, Mark I; Rahman, M Mukhlesur; Gibbons, Simon; Piddock, Laura J V

    2011-02-01

    It was hypothesised that extracts from plants that are used as herbal medicinal products contain inhibitors of efflux in Gram-negative bacteria. Extracts from 21 plants were screened by bioassay for synergy with ciprofloxacin against Salmonella enterica serotype Typhimurium, including mutants in which acrB and tolC had been inactivated. The most active extracts, fractions and purified compounds were further examined by minimum inhibitory concentration testing with five antibiotics for activity against Enterobacteriaceae and Pseudomonas aeruginosa. Efflux activity was determined using the fluorescent dye Hoechst 33342. Eighty-four extracts from 21 plants, 12 fractions thereof and 2 purified molecules were analysed. Of these, 12 plant extracts showed synergy with ciprofloxacin, 2 of which had activity suggesting efflux inhibition. The most active extract, from Levisticum officinale, was fractionated and the two fractions displaying the greatest synergy with the five antibiotics were further analysed. From these two fractions, falcarindiol and the fatty acids oleic acid and linoleic acid were isolated. The fractions and compounds possessed antibacterial activity especially for mutants lacking a component of AcrAB-TolC. However, no synergism was seen with the fractions or purified molecules, suggesting that a combination of compounds is required for efflux inhibition. These data indicate that medicinal plant extracts may provide suitable lead compounds for future development and possible clinical utility as inhibitors of efflux for various Gram-negative bacteria. Copyright © 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  11. Beta-lactamase induction and cell wall metabolism in Gram-negative bacteria

    Science.gov (United States)

    Zeng, Ximin; Lin, Jun

    2013-01-01

    Production of beta-lactamases, the enzymes that degrade beta-lactam antibiotics, is the most widespread and threatening mechanism of antibiotic resistance. In the past, extensive research has focused on the structure, function, and ecology of beta-lactamases while limited efforts were placed on the regulatory mechanisms of beta-lactamases. Recently, increasing evidence demonstrate a direct link between beta-lactamase induction and cell wall metabolism in Gram-negative bacteria. Specifically, expression of beta-lactamase could be induced by the liberated murein fragments, such as muropeptides. This article summarizes current knowledge on cell wall metabolism, beta-lactam antibiotics, and beta-lactamases. In particular, we comprehensively reviewed recent studies on the beta-lactamase induction by muropeptides via two major molecular mechanisms (the AmpG–AmpR–AmpC pathway and BlrAB-like two-component regulatory system) in Gram-negative bacteria. The signaling pathways for beta-lactamase induction offer a broad array of promising targets for the discovery of new antibacterial drugs used for combination therapies. Therefore, to develop effective mitigation strategies against the widespread beta-lactam resistance, examination of the molecular basis of beta-lactamase induction by cell wall fragment is highly warranted. PMID:23734147

  12. Survival and detection of coliforms, Enterobacteriaceae, and gram-negative bacteria in Greek yogurt.

    Science.gov (United States)

    Hervert, C J; Martin, N H; Boor, K J; Wiedmann, M

    2017-02-01

    Despite the widespread use of coliforms as indicator bacteria, increasing evidence suggests that the Enterobacteriaceae (EB) and total gram-negative groups more accurately reflect the hygienic status of high-temperature, short-time pasteurized milk and processing environments. If introduced into milk as postpasteurization contamination, these bacteria may grow to high levels and produce a wide range of sensory-related defects. However, limited information is available on the use and survival of bacterial hygiene indicators in dairy products outside of pasteurized fluid milk and cheese. The goal of this study was to (1) provide information on the survival of a diverse set of bacterial hygiene indicators in the low pH environment of Greek yogurt, (2) compare traditional and alternative detection methods for their ability to detect bacterial hygiene indicators in Greek yogurt, and (3) offer insight into optimal hygiene indicator groups for use in low-pH fermented dairy products. To this end, we screened 64 bacterial isolates, representing 24 dairy-relevant genera, for survival and detection in Greek yogurt using 5 testing methods. Before testing, isolates were inoculated into plain, 0% fat Greek yogurt (pH 4.35 to 4.65), followed by a 12-h hold period at 4 ± 1°C. Yogurts were subsequently tested using Coliform Petrifilm (3M, St. Paul, MN) to detect coliforms; Enterobacteriaceae Petrifilm (3M), violet red bile glucose agar and the D-Count (bioMérieux, Marcy-l'Étoile, France) to detect EB; and crystal violet tetrazolium agar (CVTA) to detect total gram-negative bacteria. Overall, the non-EB gram-negative isolates showed significantly larger log reductions 12 h after inoculation into Greek yogurt (based on bacterial numbers recovered on CVTA) compared with the coliform and noncoliform EB isolates tested. The methods evaluated varied in their ability to detect different microbial hygiene indicators in Greek yogurt. Crystal violet tetrazolium agar detected the highest

  13. Low antibiotic resistance among anaerobic Gram-negative bacteria in periodontitis 5 years following metronidazole therapy.

    Science.gov (United States)

    Dahlen, G; Preus, H R

    2017-02-01

    The objective of this study was to assess antibiotic susceptibility among predominant Gram-negative anaerobic bacteria isolated from periodontitis patients who 5 years prior had been subject to mechanical therapy with or without adjunctive metronidazole. One pooled sample was taken from the 5 deepest sites of each of 161 patients that completed the 5 year follow-up after therapy. The samples were analyzed by culture. A total number of 85 anaerobic strains were isolated from the predominant subgingival flora of 65/161 patient samples, identified, and tested for antibiotic susceptibility by MIC determination. E-tests against metronidazole, penicillin, amoxicillin, amoxicillin + clavulanic acid and clindamycin were employed. The 73/85 strains were Gram-negative rods (21 Porphyromonas spp., 22 Prevotella/Bacteroides spp., 23 Fusobacterium/Filifactor spp., 3 Campylobacter spp. and 4 Tannerella forsythia). These were all isolated from the treated patients irrespective of therapy procedures (+/-metronidazole) 5 years prior. Three strains (Bifidobacterium spp., Propionibacterium propionicum, Parvimonas micra) showed MIC values for metronidazole over the European Committee on Antimicrobial Susceptibility Testing break point of >4 μg/mL. All Porphyromonas and Tannerella strains were highly susceptible. Metronidazole resistant Gram-negative strains were not found, while a few showed resistance against beta-lactam antibiotics. In this population of 161 patients who had been subject to mechanical periodontal therapy with or without adjunct metronidazole 5 years prior, no cultivable antibiotic resistant anaerobes were found in the predominant subgingival microbiota. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Multiparametric Profiling for Identification of Chemosensitizers against Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Vincent Lôme

    2018-02-01

    Full Text Available Antibiotic resistance is now a worldwide therapeutic problem. Since the beginning of anti-infectious treatment bacteria have rapidly shown an incredible ability to develop and transfer resistance mechanisms. In the last decades, the design variation of pioneer bioactive molecules has strongly improved their activity and the pharmaceutical companies partly won the race against the clock. Since the 1980s, the new classes of antibiotics that emerged were mainly directed to Gram-positive bacteria. Thus, we are now facing to multidrug-resistant Gram-negative bacteria, with no therapeutic options to deal with them. These bacteria are mainly resistant because of their double membrane that conjointly impairs antibiotic accumulation and extrudes these molecules when entered. The main challenge is to allow antibiotics to cross the impermeable envelope and reach their targets. One promising solution would be to associate, in a combination therapy, a usual antibiotic with a non-antibiotic chemosensitizer. Nevertheless, for effective drug discovery, there is a prominent lack of tools required to understand the rules of permeation and accumulation into Gram-negative bacteria. By the use of a multidrug-resistant enterobacteria, we introduce a high-content screening procedure for chemosensitizers discovery by quantitative assessment of drug accumulation, alteration of barriers, and deduction of their activity profile. We assembled and analyzed a control chemicals library to perform the proof of concept. The analysis was based on real-time monitoring of the efflux alteration and measure of the influx increase in the presence of studied compounds in an automatized bio-assay. Then, synergistic activity of compounds with an antibiotic was studied and kinetic data reduction was performed which led to the calculation of a score for each barrier to be altered.

  15. The bovine acute phase response to endotoxin and Gram-negative bacteria

    DEFF Research Database (Denmark)

    Jacobsen, Stine

    exposure to LPS were employed: 1) intravenous bolus injection of Escherichia coli (E. coli) LPS inducing systemic inflammation (Papers I-III and Reports I and II), and 2) intramammary inoculation with E. coli inducing infection and local inflammation in the mammary gland (Paper IV). Systemic inflammation...... it appeared in the systemic circulation suggests that extrahepatic synthesis of SAA takes place in the inflamed udder. SAA levels in plasma and milk were very low prior to inoculation, increased rapidly and exponentially after inoculation, and returned quickly to the baseline after the infection was cleared...... aimed at containing infections, eliminating bacteria and restoring homeostasis. However, during infections or disease complexes in which LPS and/or Gram-negative bacteria persist, disease and pathological changes may result from the prolonged inflammatory response. For example, protracted LPS...

  16. Sonodynamic Excitation of Rose Bengal for Eradication of Gram-Positive and Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Faina Nakonechny

    2013-01-01

    Full Text Available Photodynamic antimicrobial chemotherapy based on photosensitizers activated by illumination is limited by poor penetration of visible light through skin and tissues. In order to overcome this problem, Rose Bengal was excited in the dark by 28 kHz ultrasound and was applied for inactivation of bacteria. It is demonstrated, for the first time, that the sonodynamic technique is effective for eradication of Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The net sonodynamic effect was calculated as a 3-4 log10 reduction in bacteria concentration, depending on the cell and the Rose Bengal concentration and the treatment time. Sonodynamic treatment may become a novel and effective form of antimicrobial therapy and can be used for low-temperature sterilization of medical instruments and surgical accessories.

  17. Cell wall elongation mode in Gram-negative bacteria is determined by peptidoglycan architecture.

    Science.gov (United States)

    Turner, Robert D; Hurd, Alexander F; Cadby, Ashley; Hobbs, Jamie K; Foster, Simon J

    2013-01-01

    Cellular integrity and morphology of most bacteria is maintained by cell wall peptidoglycan, the target of antibiotics essential in modern healthcare. It consists of glycan strands, cross-linked by peptides, whose arrangement determines cell shape, prevents lysis due to turgor pressure and yet remains dynamic to allow insertion of new material, and hence growth. The cellular architecture and insertion pattern of peptidoglycan have remained elusive. Here we determine the peptidoglycan architecture and dynamics during growth in rod-shaped Gram-negative bacteria. Peptidoglycan is made up of circumferentially oriented bands of material interspersed with a more porous network. Super-resolution fluorescence microscopy reveals an unexpected discontinuous, patchy synthesis pattern. We present a consolidated model of growth via architecture-regulated insertion, where we propose only the more porous regions of the peptidoglycan network that are permissive for synthesis.

  18. Structural modifications of bacterial lipopolysaccharide that facilitate Gram-negative bacteria evasion of host innate immunity

    Directory of Open Access Journals (Sweden)

    Motohiro eMatsuura

    2013-05-01

    Full Text Available Bacterial lipopolysaccharide (LPS, a cell wall component characteristic of Gram-negative bacteria, is a representative pathogen-associated molecular pattern that allows mammalian cells to recognize bacterial invasion and trigger innate immune responses. The polysaccharide moiety of LPS primary plays protective roles for bacteria such as prevention from complement attacks or camouflage with common host carbohydrate residues. The lipid moiety, termed lipid A, is recognized by the Toll-like receptor 4 (TLR4/MD-2 complex, which transduces signals for activation of host innate immunity. The basic structure of lipid A is a glucosamine disaccharide substituted by phosphate groups and acyl groups. Lipid A with 6 acyl groups (hexa-acylated form has been indicated to be a strong stimulator of the TLR4/MD-2 complex. This type of lipid A is conserved among a wide variety of Gram-negative bacteria, and those bacteria are easily recognized by host cells for activation of defensive innate immune responses. Modifications of the lipid A structure to less-acylated forms have been observed in some bacterial species, and those forms are poor stimulators of the TLR4/MD-2 complex. Such modifications are thought to facilitate bacterial evasion of host innate immunity, thereby enhancing pathogenicity. This hypothesis is supported by studies of Yersinia pestis LPS, which contains hexa-acylated lipid A when the bacterium grows at 27ºC (the temperature of the vector flea, and shifts to contain less-acylated forms when grown at the human body temperature of 37ºC. This alteration of lipid A forms following transmission of Y. pestis from fleas to humans contributes predominantly to the virulence of this bacterium over other virulence factors. A similar role for less-acylated lipid A forms has been indicated in some other bacterial species, such as Francisella tularensis, Helicobacter pylori, and Porphyromonas gingivalis, and further studies to explore this concept are

  19. A new family of lysozyme inhibitors contributing to lysozyme tolerance in gram-negative bacteria.

    Directory of Open Access Journals (Sweden)

    Lien Callewaert

    2008-03-01

    Full Text Available Lysozymes are ancient and important components of the innate immune system of animals that hydrolyze peptidoglycan, the major bacterial cell wall polymer. Bacteria engaging in commensal or pathogenic interactions with an animal host have evolved various strategies to evade this bactericidal enzyme, one recently proposed strategy being the production of lysozyme inhibitors. We here report the discovery of a novel family of bacterial lysozyme inhibitors with widespread homologs in gram-negative bacteria. First, a lysozyme inhibitor was isolated by affinity chromatography from a periplasmic extract of Salmonella Enteritidis, identified by mass spectrometry and correspondingly designated as PliC (periplasmic lysozyme inhibitor of c-type lysozyme. A pliC knock-out mutant no longer produced lysozyme inhibitory activity and showed increased lysozyme sensitivity in the presence of the outer membrane permeabilizing protein lactoferrin. PliC lacks similarity with the previously described Escherichia coli lysozyme inhibitor Ivy, but is related to a group of proteins with a common conserved COG3895 domain, some of them predicted to be lipoproteins. No function has yet been assigned to these proteins, although they are widely spread among the Proteobacteria. We demonstrate that at least two representatives of this group, MliC (membrane bound lysozyme inhibitor of c-type lysozyme of E. coli and Pseudomonas aeruginosa, also possess lysozyme inhibitory activity and confer increased lysozyme tolerance upon expression in E. coli. Interestingly, mliC of Salmonella Typhi was picked up earlier in a screen for genes induced during residence in macrophages, and knockout of mliC was shown to reduce macrophage survival of S. Typhi. Based on these observations, we suggest that the COG3895 domain is a common feature of a novel and widespread family of bacterial lysozyme inhibitors in gram-negative bacteria that may function as colonization or virulence factors in bacteria

  20. A New Family of Lysozyme Inhibitors Contributing to Lysozyme Tolerance in Gram-Negative Bacteria

    Science.gov (United States)

    Callewaert, Lien; Aertsen, Abram; Deckers, Daphne; Vanoirbeek, Kristof G. A.; Vanderkelen, Lise; Van Herreweghe, Joris M.; Masschalck, Barbara; Nakimbugwe, Dorothy; Robben, Johan; Michiels, Chris W.

    2008-01-01

    Lysozymes are ancient and important components of the innate immune system of animals that hydrolyze peptidoglycan, the major bacterial cell wall polymer. Bacteria engaging in commensal or pathogenic interactions with an animal host have evolved various strategies to evade this bactericidal enzyme, one recently proposed strategy being the production of lysozyme inhibitors. We here report the discovery of a novel family of bacterial lysozyme inhibitors with widespread homologs in gram-negative bacteria. First, a lysozyme inhibitor was isolated by affinity chromatography from a periplasmic extract of Salmonella Enteritidis, identified by mass spectrometry and correspondingly designated as PliC (periplasmic lysozyme inhibitor of c-type lysozyme). A pliC knock-out mutant no longer produced lysozyme inhibitory activity and showed increased lysozyme sensitivity in the presence of the outer membrane permeabilizing protein lactoferrin. PliC lacks similarity with the previously described Escherichia coli lysozyme inhibitor Ivy, but is related to a group of proteins with a common conserved COG3895 domain, some of them predicted to be lipoproteins. No function has yet been assigned to these proteins, although they are widely spread among the Proteobacteria. We demonstrate that at least two representatives of this group, MliC (membrane bound lysozyme inhibitor of c-type lysozyme) of E. coli and Pseudomonas aeruginosa, also possess lysozyme inhibitory activity and confer increased lysozyme tolerance upon expression in E. coli. Interestingly, mliC of Salmonella Typhi was picked up earlier in a screen for genes induced during residence in macrophages, and knockout of mliC was shown to reduce macrophage survival of S. Typhi. Based on these observations, we suggest that the COG3895 domain is a common feature of a novel and widespread family of bacterial lysozyme inhibitors in gram-negative bacteria that may function as colonization or virulence factors in bacteria interacting with

  1. Biofilms Formed by Gram-Negative Bacteria Undergo Increased Lipid A Palmitoylation, Enhancing In Vivo Survival

    Science.gov (United States)

    Chalabaev, Sabina; Chauhan, Ashwini; Novikov, Alexey; Iyer, Pavithra; Szczesny, Magdalena; Beloin, Christophe; Caroff, Martine

    2014-01-01

    ABSTRACT Bacterial biofilm communities are associated with profound physiological changes that lead to novel properties compared to the properties of individual (planktonic) bacteria. The study of biofilm-associated phenotypes is an essential step toward control of deleterious effects of pathogenic biofilms. Here we investigated lipopolysaccharide (LPS) structural modifications in Escherichia coli biofilm bacteria, and we showed that all tested commensal and pathogenic E. coli biofilm bacteria display LPS modifications corresponding to an increased level of incorporation of palmitate acyl chain (palmitoylation) into lipid A compared to planktonic bacteria. Genetic analysis showed that lipid A palmitoylation in biofilms is mediated by the PagP enzyme, which is regulated by the histone-like protein repressor H-NS and the SlyA regulator. While lipid A palmitoylation does not influence bacterial adhesion, it weakens inflammatory response and enhances resistance to some antimicrobial peptides. Moreover, we showed that lipid A palmitoylation increases in vivo survival of biofilm bacteria in a clinically relevant model of catheter infection, potentially contributing to biofilm tolerance to host immune defenses. The widespread occurrence of increased lipid A palmitoylation in biofilms formed by all tested bacteria suggests that it constitutes a new biofilm-associated phenotype in Gram-negative bacteria. PMID:25139899

  2. Molecular Structure of Endotoxins from Gram-negative Marine Bacteria: An Update

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    Antonio Molinaro

    2007-09-01

    Full Text Available Marine bacteria are microrganisms that have adapted, through millions of years, to survival in environments often characterized by one or more extreme physical or chemical parameters, namely pressure, temperature and salinity. The main interest in the research on marine bacteria is due to their ability to produce several biologically active molecules, such as antibiotics, toxins and antitoxins, antitumor and antimicrobial agents. Nonetheless, lipopolysaccharides (LPSs, or their portions, from Gram-negative marine bacteria, have often shown low virulence, and represent potential candidates in the development of drugs to prevent septic shock. Besides, the molecular architecture of such molecules is related to the possibility of thriving in marine habitats, shielding the cell from the disrupting action of natural stress factors. Over the last few years, the depiction of a variety of structures of lipids A, core oligosaccharides and O-specific polysaccharides from LPSs of marine microrganisms has been given. In particular, here we will examine the most recently encountered structures for bacteria belonging to the genera Shewanella, Pseudoalteromonas and Alteromonas, of the γ-Proteobacteria phylum, and to the genera Flavobacterium, Cellulophaga, Arenibacter and Chryseobacterium, of the Cytophaga- Flavobacterium-Bacteroides phylum. Particular attention will be paid to the chemical features expressed by these structures (characteristic monosaccharides, non-glycidic appendages, phosphate groups, to the typifying traits of LPSs from marine bacteria and to the possible correlation existing between such features and the adaptation, over years, of bacteria to marine environments.

  3. Molecular structure of endotoxins from Gram-negative marine bacteria: an update.

    Science.gov (United States)

    Leone, Serena; Silipo, Alba; L Nazarenko, Evgeny; Lanzetta, Rosa; Parrilli, Michelangelo; Molinaro, Antonio

    2007-09-19

    Marine bacteria are microrganisms that have adapted, through millions of years, to survival in environments often characterized by one or more extreme physical or chemical parameters, namely pressure, temperature and salinity. The main interest in the research on marine bacteria is due to their ability to produce several biologically active molecules, such as antibiotics, toxins and antitoxins, antitumor and antimicrobial agents. Nonetheless, lipopolysaccharides (LPSs), or their portions, from Gram-negative marine bacteria, have often shown low virulence, and represent potential candidates in the development of drugs to prevent septic shock. Besides, the molecular architecture of such molecules is related to the possibility of thriving in marine habitats, shielding the cell from the disrupting action of natural stress factors. Over the last few years, the depiction of a variety of structures of lipids A, core oligosaccharides and O-specific polysaccharides from LPSs of marine microrganisms has been given. In particular, here we will examine the most recently encountered structures for bacteria belonging to the genera Shewanella, Pseudoalteromonas and Alteromonas, of the gamma-Proteobacteria phylum, and to the genera Flavobacterium, Cellulophaga, Arenibacter and Chryseobacterium, of the Cytophaga-Flavobacterium-Bacteroides phylum. Particular attention will be paid to the chemical features expressed by these structures (characteristic monosaccharides, non-glycidic appendages, phosphate groups), to the typifying traits of LPSs from marine bacteria and to the possible correlation existing between such features and the adaptation, over years, of bacteria to marine environments.

  4. Characterization of carbapenem-resistant Gram-negative bacteria from Tamil Nadu.

    Science.gov (United States)

    Nachimuthu, Ramesh; Subramani, Ramkumar; Maray, Suresh; Gothandam, K M; Sivamangala, Karthikeyan; Manohar, Prasanth; Bozdogan, Bülent

    2016-10-01

    Carbapenem resistance is disseminating worldwide among Gram-negative bacteria. The aim of this study was to identify carbapenem-resistance level and to determine the mechanism of carbapenem resistance among clinical isolates from two centres in Tamil Nadu. In the present study, a total of 93 Gram-negative isolates, which is found to be resistant to carbapenem by disk diffusion test in two centres, were included. All isolates are identified at species level by 16S rRNA sequencing. Minimal inhibitory concentrations (MICs) of isolates for Meropenem were tested by agar dilution method. Presence of blaOXA, blaNDM, blaVIM, blaIMP and blaKPC genes was tested by PCR in all isolates. Amplicons were sequenced for confirmation of the genes. Among 93 isolates, 48 (%52) were Escherichia coli, 10 (%11) Klebsiella pneumoniae, nine (%10) Pseudomonas aeruginosa. Minimal inhibitory concentration results showed that of 93 suspected carbapenem-resistant isolates, 27 had meropenem MICs ≥ 2 μg/ml. The MIC range, MIC50 and MIC90 were 128 μg/ml, 0.12 and 16 μg/ml, respectively. Fig. 1 . Among meropenem-resistant isolates, E. coli were the most common (9/48, 22%), followed by K. pneumoniae (7/9, 77%), P. aeruginosa (6/10, 60%), Acinetobacter baumannii (2/2, 100%), Enterobacter hormaechei (2/3, 67%) and one Providencia rettgeri (1/1, 100%). PCR results showed that 16 of 93 carried blaNDM, three oxa181, and one imp4. Among blaNDM carriers, nine were E. coli, four Klebsiella pneumoniae, two E. hormaechei and one P. rettgeri. Three K. pneumoniae were OXA-181 carriers. The only imp4 carrier was P. aeruginosa. A total of seven carbapenem-resistant isolates were negatives by PCR for the genes studied. All carbapenem-resistance gene-positive isolates had meropenem MICs >2 μg/ml. Our results confirm the dissemination of NDM and emergence of OXA-181 beta-lactamase among Gram-negative bacteria in South India. This study showed the emergence of NDM producer in clinical isolates of E

  5. Evaluation of post-antibiotic effect in Gram-negative and Gram-positive bacteria

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    Elisa Tavella

    2008-03-01

    Full Text Available Although the postantibiotic effect (PAE is a well recognized phenomenon, the mechanism by which it is induced has not fully elucidated yet. It has been suggested that PAE is the time required by bacteria to synthesize proteins or mRNA characterized by a short half-life that are consumed during antibiotic treatment.This phenomenon is widely studied on Gram-positive cocci and Gram-negative rods, while information about Gram-positive rods and Gram-negative cocci are scanty.To gain new insights on the PAE, this study was addressed to evaluated the time required by Moraxella catarrhalis and Lactobacillus planctarum to resume their physiological growth rate after exposure to various antibiotics. Methods PAE was estimated in accordance with the method of Craig and Gudmundsson using the following drugs: penicillin, piperacillin-tazobactam, cefalotin, ceftazidime, imipenem, ciprofloxacin, gentamycin and azithromycin. Log-phase bacteria were exposed to drug at a concentration corresponding to 4 times the MIC value for 1h.The drug was inactivated by 1:1000 dilution. Bacterial counts were determined at time zero, immediately after drug dilution, and at each hour after removal for 6 - 7h by a pour-plate technique. The PAE was defined as the difference in time required by test and control cultures to increase by 1 log in CFU number. Results All drugs tested induced a PAE on the strains studied. M. catarrhalis registered PAE values ranging between 0,5 (gentamycin and 2 (ceftazidime, imipenem and azithromycin.With respect to L. plantarum a PAE between 0,8 (cefalotin and 3 hours (ciprofloxacin were detected. Conclusion. These findings demonstrated that all the drugs tested were able to induce a PAE on the strains tested.This observation differs from that observed on Gram-negative rods characterised by negative PAE values induced by penicillins and cephalosporins.This results might reflect the different target of these compounds on these Gram-positive rods or the

  6. Antiseptic and antibiotic resistance in Gram-negative bacteria causing urinary tract infection.

    Science.gov (United States)

    Stickler, D J; Thomas, B

    1980-01-01

    A collection of 802 isolates of Gram-negative bacteria causing urinary tract infections was made from general practice, antenatal clinics, and local hospitals. The organisms were tested for their sensitivity to chlorhexidine, cetrimide, glutaraldehyde, phenyl mercuric nitrate, a phenolic formulation, and a proprietary antiseptic containing a mixture of picloxydine, octyl phenoxy polyethoxyethanol, and benzalkonium chloride. Escherichia coli, the major species isolated, proved to be uniformly sensitive to these agents. Approximately 10% of the total number of isolates, however, exhibited a degree of resistance to the cationic agents. These resistant organisms were members of the genera Proteus, Providencia, and Pseudomonas; they were also generally resistant to five, six, or seven antibiotics. It is proposed therefore that an antiseptic policy which involves the intensive use of cationic antiseptics might lead to the selection of a flora of notoriously drug-resistant species. PMID:6769972

  7. Motuporamine Derivatives as Antimicrobial Agents and Antibiotic Enhancers against Resistant Gram-Negative Bacteria.

    Science.gov (United States)

    Borselli, Diane; Blanchet, Marine; Bolla, Jean-Michel; Muth, Aaron; Skruber, Kristen; Phanstiel, Otto; Brunel, Jean Michel

    2017-02-01

    Dihydromotuporamine C and its derivatives were evaluated for their in vitro antimicrobial activities and antibiotic enhancement properties against Gram-negative bacteria and clinical isolates. The mechanism of action of one of these derivatives, MOTU-N44, was investigated against Enterobacter aerogenes by using fluorescent dyes to evaluate outer-membrane depolarization and permeabilization. Its efficiency correlated with inhibition of dye transport, thus suggesting that these molecules inhibit drug transporters by de-energization of the efflux pump rather than by direct interaction of the molecule with the pump. This suggests that depowering the efflux pump provides another strategy to address antibiotic resistance. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  8. A survey of gram-negative bacteria survival on hospital fabrics and plastics.

    Science.gov (United States)

    Neely, A N

    2000-01-01

    One critical factor for the transmission of microorganisms from person to person or from the environment to a person (patient or health care worker) is the ability of the microbe to survive on an environmental surface. The purpose of this study was to determine the length of survival of various gram-negative bacteria on fabrics and plastics commonly used in hospitals. Seven materials were tested: smooth cotton (clothing), cotton terry (towels), 60% cotton-40% polyester blend (scrub suits and lab coats), polyester (drapes), 75% nylon-25% spandex (pressure garments), polyvinyl (splash aprons), and polyurethane (keyboard covers). The following bacteria were tested: Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Proteus mirabilis, Acinetobacter species, and Enterobacter species. Swatches of the materials were inoculated with defined amounts of bacteria and assayed at regular intervals. Survival was dependent on the bacterium, its inoculum size, and the material tested. At 102 microorganisms per swatch, bacteria survived from less than 1 hour to 8 days. At 10(4) to 10(5) bacteria per swatch, survival ranged from 2 hours to more than 60 days. These findings emphasize the need for careful disinfection and conscientious contact control procedures in areas that serve immunosuppressed individuals, such as patients with burn injuries.

  9. Epidemiology and molecular characterization of multidrug-resistant Gram-negative bacteria in Southeast Asia

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    Nuntra Suwantarat

    2016-05-01

    Full Text Available Abstract Background Multidrug-resistant Gram-negative bacteria (MDRGN, including extended-spectrum β-lactamases (ESBLs and multidrug-resistant glucose-nonfermenting Gram-negative bacilli (nonfermenters, have emerged and spread throughout Southeast Asia. Methods We reviewed and summarized current critical knowledge on the epidemiology and molecular characterization of MDRGN in Southeast Asia by PubMed searches for publications prior to 10 March 2016 with the term related to “MDRGN definition” combined with specific Southeast Asian country names (Thailand, Singapore, Malaysia, Vietnam, Indonesia, Philippines, Laos, Cambodia, Myanmar, Brunei. Results There were a total of 175 publications from the following countries: Thailand (77, Singapore (35, Malaysia (32, Vietnam (23, Indonesia (6, Philippines (1, Laos (1, and Brunei (1. We did not find any publications on MDRGN from Myanmar and Cambodia. We did not include publications related to Shigella spp., Salmonella spp., and Vibrio spp. and non-human related studies in our review. English language articles and abstracts were included for analysis. After the abstracts were reviewed, data on MDRGN in Southeast Asia from 54 publications were further reviewed and included in this study. Conclusions MDRGNs are a major contributor of antimicrobial-resistant bacteria in Southeast Asia. The high prevalence of ESBLs has been a major problem since 2005 and is possibly related to the development of carbapenem resistant organisms in this region due to the overuse of carbapenem therapy. Carbapenem–resistant Acinetobacter baumannii is the most common pathogen associated with nosocomial infections in this region followed by carbapenem-resistant Pseudomonas aeruginosa. Although Southeast Asia is not an endemic area for carbapenem-resistant Enterobacteriaceae (CRE, recently, the rate of CRE detection has been increasing. Limited infection control measures, lack of antimicrobial control, such as the presence of

  10. Synergistic action of Galleria mellonella apolipophorin III and lysozyme against Gram-negative bacteria.

    Science.gov (United States)

    Zdybicka-Barabas, Agnieszka; Stączek, Sylwia; Mak, Paweł; Skrzypiec, Krzysztof; Mendyk, Ewaryst; Cytryńska, Małgorzata

    2013-06-01

    Insect immune response relies on the humoral and cellular mechanisms of innate immunity. The key factors are the antimicrobial polypeptides that act in concert against invading pathogens. Several such components, e.g. apolipophorin III (apoLp-III), lysozyme, and anionic peptide 2, are present constitutively in the hemolymph of non-challenged Galleria mellonella larvae. In the present study, we demonstrate an evidence for a synergistic action of G. mellonella lysozyme and apoLp-III against Gram-negative bacteria, providing novel insights into the mode of action of these proteins in insect antimicrobial defense. It was found that the muramidase activity of G. mellonella lysozyme considerably increased in the presence of apoLp-III. Moreover, apoLp-III enhanced the permeabilizing activity of lysozyme toward Escherichia coli cells. As shown using non-denaturing PAGE, the proteins did not form intermolecular complexes in vivo and in vitro, indicating that the effect observed was not connected with the intermolecular interactions between the proteins. Analysis of AFM images of E. coli cells exposed to G. mellonella lysozyme and/or apoLp-III revealed evident alterations in the bacterial surface structure accompanied by the changes in their biophysical properties. The bacterial cells demonstrated significant differences in elasticity, reflected by Young's modulus, as well as in adhesive forces and roughness values in comparison to the control ones. The constitutive presence of these two defense molecules in G. mellonella hemolymph and the fact that apoLp-III enhances lysozyme muramidase and perforating activities indicate that they can be regarded as important antibacterial factors acting at the early stage of infection against Gram-negative as well as Gram-positive bacteria. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Antibacterial activities of selected edible plants extracts against multidrug-resistant Gram-negative bacteria.

    Science.gov (United States)

    Djeussi, Doriane E; Noumedem, Jaurès A K; Seukep, Jackson A; Fankam, Aimé G; Voukeng, Igor K; Tankeo, Simplice B; Nkuete, Antoine H L; Kuete, Victor

    2013-07-10

    In response to the propagation of bacteria resistant to many antibiotics also called multi-drug resistant (MDR) bacteria, the discovery of new and more efficient antibacterial agents is primordial. The present study was aimed at evaluating the antibacterial activities of seven Cameroonian dietary plants (Adansonia digitata, Aframomum alboviolaceum, Aframomum polyanthum, Anonidium. mannii, Hibiscus sabdarifa, Ocimum gratissimum and Tamarindus indica). The phytochemical screening of the studied extracts was performed using described methods whilst the liquid broth micro dilution was used for all antimicrobial assays against 27 Gram-negative bacteria. The results of the phytochemical tests indicate that all tested extracts contained phenols and triterpenes, other classes of chemicals being selectively present. The studied extracts displayed various degrees of antibacterial activities. The extracts of A. digitata, H. sabdarifa, A. polyanthum, A. alboviolaceum and O. gratissimum showed the best spectra of activity, their inhibitory effects being recorded against 81.48%, 66.66%, 62.96%, 55.55%, and 55.55% of the 27 tested bacteria respectively. The extract of A. polyanthum was very active against E. aerogenes EA294 with the lowest recorded minimal inhibitory concentration (MIC) of 32 μg/ml. The results of the present work provide useful baseline information for the potential use of the studied edible plants in the fight against both sensitive and MDR phenotypes.

  12. Trends of 9,416 multidrug-resistant Gram-negative bacteria

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    Viviane Decicera Colombo Oliveira

    2015-06-01

    Full Text Available Summary Objective: a resistance of hospital-acquired bacteria to multiple antibiotics is a major concern worldwide. The objective of this study was to investigate multidrugresistant (MDR bacteria, clinical specimens, origin of specimen and trends, and correlate these with bacterial sensitivity and consumption of antimicrobials. Methods: 9,416 bacteria of nosocomial origin were evaluated in a tertiary hospital, from 1999 to 2008. MDR was defined for Gram-negative bacteria (GNB as resistance to two or more classes/groups of antibiotics. Results: GNB MDR increased by 3.7 times over the study period (p<0.001. Acinetobacter baumannii was the most prevalent (36.2%. Over the study period, there were significant 4.8-fold and 14.6-fold increases for A. baumannii and K. pneumoniae (p<0.001, respectively. Sixty-seven percent of isolates of MDR GNB were isolated in intensive care units. The resistance of A. baumannii to carbapenems increased from 7.4 to 57.5% during the study period and concomitant with an increased consumption. Conclusion: that decade showed prevalence of GNB and a gradual increase in MDR GNB. There was an increase in carbapenem resistance of 50.1% during the study.

  13. Emergence of Imipenem-Resistant Gram-Negative Bacilli in Intestinal Flora of Intensive Care Patients

    Science.gov (United States)

    Angebault, Cécile; Barbier, François; Hamelet, Emilie; Defrance, Gilles; Ruppé, Etienne; Bronchard, Régis; Lepeule, Raphaël; Lucet, Jean-Christophe; El Mniai, Assiya; Wolff, Michel; Montravers, Philippe; Plésiat, Patrick; Andremont, Antoine

    2013-01-01

    Intestinal flora contains a reservoir of Gram-negative bacilli (GNB) resistant to cephalosporins, which are potentially pathogenic for intensive care unit (ICU) patients; this has led to increasing use of carbapenems. The emergence of carbapenem resistance is a major concern for ICUs. Therefore, in this study, we aimed to assess the intestinal carriage of imipenem-resistant GNB (IR-GNB) in intensive care patients. For 6 months, 523 consecutive ICU patients were screened for rectal IR-GNB colonization upon admission and weekly thereafter. The phenotypes and genotypes of all isolates were determined, and a case control study was performed to identify risk factors for colonization. The IR-GNB colonization rate increased regularly from 5.6% after 1 week to 58.6% after 6 weeks in the ICU. In all, 56 IR-GNB strains were collected from 50 patients: 36 Pseudomonas aeruginosa strains, 12 Stenotrophomonas maltophilia strains, 6 Enterobacteriaceae strains, and 2 Acinetobacter baumannii strains. In P. aeruginosa, imipenem resistance was due to chromosomally encoded resistance (32 strains) or carbapenemase production (4 strains). In the Enterobacteriaceae strains, resistance was due to AmpC cephalosporinase and/or extended-spectrum β-lactamase production with porin loss. Genomic comparison showed that the strains were highly diverse, with 8 exceptions (4 VIM-2 carbapenemase-producing P. aeruginosa strains, 2 Klebsiella pneumoniae strains, and 2 S. maltophilia strains). The main risk factor for IR-GNB colonization was prior imipenem exposure. The odds ratio for colonization was already as high as 5.9 (95% confidence interval [95% CI], 1.5 to 25.7) after 1 to 3 days of exposure and increased to 7.8 (95% CI, 2.4 to 29.8) thereafter. In conclusion, even brief exposure to imipenem is a major risk factor for IR-GNB carriage. PMID:23318796

  14. Coprinopsis cinerea intracellular lactonases hydrolyze quorum sensing molecules of Gram-negative bacteria.

    Science.gov (United States)

    Stöckli, Martina; Lin, Chia-Wei; Sieber, Ramon; Plaza, David F; Ohm, Robin A; Künzler, Markus

    2017-05-01

    Biofilm formation on fungal hyphae and production of antifungal molecules are strategies of bacteria in their competition with fungi for nutrients. Since these strategies are often coordinated and under control of quorum sensing by the bacteria, interference with this bacterial communication system can be used as a counter-strategy by the fungi in this competition. Hydrolysis of N-acyl-homoserine lactones (HSL), a quorum sensing molecule used by Gram-negative bacteria, by fungal cultures has been demonstrated. However, the enzymes that are responsible for this activity, have not been identified. In this study, we identified and characterized two paralogous HSL hydrolyzing enzymes from the coprophilous fungus Coprinopsis cinerea. The C. cinerea HSL lactonases belong to the metallo-β-lactamase family and show sequence homology to and a similar biochemical activity as the well characterized lactonase AiiA from Bacillus thuringiensis. We show that the fungal lactonases, similar to the bacterial enzymes, are kept intracellularly and act as a sink for the bacterial quorum sensing signals both in C. cinerea and in Saccharomyces cerevisiae expressing C. cinerea lactonases, due to the ability of these signal molecules to diffuse over the fungal cell wall and plasma membrane. The two isogenes coding for the C. cinerea HSL lactonases are arranged in the genome as a tandem repeat and expressed preferentially in vegetative mycelium. The occurrence of orthologous genes in genomes of other basidiomycetes appears to correlate with a saprotrophic lifestyle. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. The Structural Diversity of Carbohydrate Antigens of Selected Gram-Negative Marine Bacteria

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    Elena P. Ivanova

    2011-10-01

    Full Text Available Marine microorganisms have evolved for millions of years to survive in the environments characterized by one or more extreme physical or chemical parameters, e.g., high pressure, low temperature or high salinity. Marine bacteria have the ability to produce a range of biologically active molecules, such as antibiotics, toxins and antitoxins, antitumor and antimicrobial agents, and as a result, they have been a topic of research interest for many years. Among these biologically active molecules, the carbohydrate antigens, lipopolysaccharides (LPSs, O-antigens found in cell walls of Gram-negative marine bacteria, show great potential as candidates in the development of drugs to prevent septic shock due to their low virulence. The structural diversity of LPSs is thought to be a reflection of the ability for these bacteria to adapt to an array of habitats, protecting the cell from being compromised by exposure to harsh environmental stress factors. Over the last few years, the variety of structures of core oligosaccharides and O-specific polysaccharides from LPSs of marine microrganisms has been discovered. In this review, we discuss the most recently encountered structures that have been identified from bacteria belonging to the genera Aeromonas, Alteromonas, Idiomarina, Microbulbifer, Pseudoalteromonas, Plesiomonas and Shewanella of the Gammaproteobacteria phylum; Sulfitobacter and Loktanella of the Alphaproteobactera phylum and to the genera Arenibacter, Cellulophaga, Chryseobacterium, Flavobacterium, Flexibacter of the Cytophaga-Flavobacterium-Bacteroides phylum. Particular attention is paid to the particular chemical features of the LPSs, such as the monosaccharide type, non-sugar substituents and phosphate groups, together with some of the typifying traits of LPSs obtained from marine bacteria. A possible correlation is then made between such features and the environmental adaptations undertaken by marine bacteria.

  16. The structural diversity of carbohydrate antigens of selected gram-negative marine bacteria.

    Science.gov (United States)

    Nazarenko, Evgeny L; Crawford, Russell J; Ivanova, Elena P

    2011-01-01

    Marine microorganisms have evolved for millions of years to survive in the environments characterized by one or more extreme physical or chemical parameters, e.g., high pressure, low temperature or high salinity. Marine bacteria have the ability to produce a range of biologically active molecules, such as antibiotics, toxins and antitoxins, antitumor and antimicrobial agents, and as a result, they have been a topic of research interest for many years. Among these biologically active molecules, the carbohydrate antigens, lipopolysaccharides (LPSs, O-antigens) found in cell walls of gram-negative marine bacteria, show great potential as candidates in the development of drugs to prevent septic shock due to their low virulence. The structural diversity of LPSs is thought to be a reflection of the ability for these bacteria to adapt to an array of habitats, protecting the cell from being compromised by exposure to harsh environmental stress factors. Over the last few years, the variety of structures of core oligosaccharides and O-specific polysaccharides from LPSs of marine microrganisms has been discovered. In this review, we discuss the most recently encountered structures that have been identified from bacteria belonging to the genera Aeromonas, Alteromonas, Idiomarina, Microbulbifer, Pseudoalteromonas, Plesiomonas and Shewanella of the Gammaproteobacteria phylum; Sulfitobacter and Loktanella of the Alphaproteobactera phylum and to the genera Arenibacter, Cellulophaga, Chryseobacterium, Flavobacterium, Flexibacter of the Cytophaga-Flavobacterium-Bacteroides phylum. Particular attention is paid to the particular chemical features of the LPSs, such as the monosaccharide type, non-sugar substituents and phosphate groups, together with some of the typifying traits of LPSs obtained from marine bacteria. A possible correlation is then made between such features and the environmental adaptations undertaken by marine bacteria.

  17. Exploiting Quorum Sensing Interfering Strategies in Gram-Negative Bacteria for the Enhancement of Environmental Applications.

    Science.gov (United States)

    Zhang, Weiwei; Li, Chenghua

    2015-01-01

    Quorum sensing (QS) is a widespread intercellular form of communication to coordinate physiological processes and cooperative activities of bacteria at the population level, and it depends on the production, secretion, and detection of small diffusible autoinducers, such as acyl-homoserine lactones (AHLs), auto-inducing oligo-peptides (AIPs) and autoinducer 2. In this review, the function of QS autoinducers of gram-negative bacteria in different aspects of wastewater treatment systems is examined. Based on research primarily performed over the past 10 years, QS involvement in the formation of biofilm and aerobic granules and changes of the microbial community and degradation/transformation pathways is discussed. In particular, the QS pathway in the role of bacterial infections and disease prevention in aquaculture is addressed. Interference of QS autoinducer-regulated pathways is considered potential treatment for a variety of environmentally related problems. This review is expected to serve as a stepping stone for further study and development strategies based on the mediation of QS-regulated pathways to enhance applications in both wastewater treatment systems and aquaculture.

  18. The Challenge of Efflux-Mediated Antibiotic Resistance in Gram-Negative Bacteria

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    Plésiat, Patrick

    2015-01-01

    SUMMARY The global emergence of multidrug-resistant Gram-negative bacteria is a growing threat to antibiotic therapy. The chromosomally encoded drug efflux mechanisms that are ubiquitous in these bacteria greatly contribute to antibiotic resistance and present a major challenge for antibiotic development. Multidrug pumps, particularly those represented by the clinically relevant AcrAB-TolC and Mex pumps of the resistance-nodulation-division (RND) superfamily, not only mediate intrinsic and acquired multidrug resistance (MDR) but also are involved in other functions, including the bacterial stress response and pathogenicity. Additionally, efflux pumps interact synergistically with other resistance mechanisms (e.g., with the outer membrane permeability barrier) to increase resistance levels. Since the discovery of RND pumps in the early 1990s, remarkable scientific and technological advances have allowed for an in-depth understanding of the structural and biochemical basis, substrate profiles, molecular regulation, and inhibition of MDR pumps. However, the development of clinically useful efflux pump inhibitors and/or new antibiotics that can bypass pump effects continues to be a challenge. Plasmid-borne efflux pump genes (including those for RND pumps) have increasingly been identified. This article highlights the recent progress obtained for organisms of clinical significance, together with methodological considerations for the characterization of MDR pumps. PMID:25788514

  19. Exploiting quorum sensing interfering strategies in gram-negative bacteria for the enhancement of environmental applications

    Directory of Open Access Journals (Sweden)

    Weiwei eZhang

    2016-01-01

    Full Text Available Quorum sensing (QS is a widespread intercellular form of communication to coordinate physiological processes and cooperative activities of bacteria at the population level, and it depends on the production, secretion, and detection of small diffusible autoinducers, such as acyl-homoserine lactones (AHLs, auto-inducing oligo-peptides (AIPs and autoinducer 2. In this review, the function of QS autoinducers of gram-negative bacteria in different aspects of wastewater treatment systems is examined. Based on research primarily performed over the past ten years, QS involvement in the formation of biofilm and aerobic granules and changes of the microbial community and degradation/transformation pathways is discussed. In particular, the QS pathway in the role of bacterial infections and disease prevention in aquaculture is addressed. Interference of QS autoinducer-regulated pathways is considered potential treatment for a variety of environmentally related problems. This review is expected to serve as a stepping stone for further study and development strategies based on the mediation of QS-regulated pathways to enhance applications in both wastewater treatment systems and aquaculture.

  20. Multidrug-resistant Gram-negative bacteria: a product of globalization.

    Science.gov (United States)

    Hawkey, P M

    2015-04-01

    Global trade and mobility of people has increased rapidly over the last 20 years. This has had profound consequences for the evolution and the movement of antibiotic resistance genes. There is increasing exposure of populations all around the world to resistant bacteria arising in the emerging economies. Arguably the most important development of the last two decades in the field of antibiotic resistance is the emergence and spread of extended-spectrum β-lactamases (ESBLs) of the CTX-M group. A consequence of the very high rates of ESBL production among Enterobacteriaceae in Asian countries is that there is a substantial use of carbapenem antibiotics, resulting in the emergence of plasmid-mediated resistance to carbapenems. This article reviews the emergence and spread of multidrug-resistant Gram-negative bacteria, focuses on three particular carbapenemases--imipenem carbapenemases, Klebsiella pneumoniae carbapenemase, and New Delhi metallo-β-lactamase--and highlights the importance of control of antibiotic use. Copyright © 2015. Published by Elsevier Ltd.

  1. Exploiting Quorum Sensing Interfering Strategies in Gram-Negative Bacteria for the Enhancement of Environmental Applications

    Science.gov (United States)

    Zhang, Weiwei; Li, Chenghua

    2016-01-01

    Quorum sensing (QS) is a widespread intercellular form of communication to coordinate physiological processes and cooperative activities of bacteria at the population level, and it depends on the production, secretion, and detection of small diffusible autoinducers, such as acyl-homoserine lactones (AHLs), auto-inducing oligo-peptides (AIPs) and autoinducer 2. In this review, the function of QS autoinducers of gram-negative bacteria in different aspects of wastewater treatment systems is examined. Based on research primarily performed over the past 10 years, QS involvement in the formation of biofilm and aerobic granules and changes of the microbial community and degradation/transformation pathways is discussed. In particular, the QS pathway in the role of bacterial infections and disease prevention in aquaculture is addressed. Interference of QS autoinducer-regulated pathways is considered potential treatment for a variety of environmentally related problems. This review is expected to serve as a stepping stone for further study and development strategies based on the mediation of QS-regulated pathways to enhance applications in both wastewater treatment systems and aquaculture. PMID:26779175

  2. Glyphosate application increased catabolic activity of gram-negative bacteria but impaired soil fungal community.

    Science.gov (United States)

    Liu, Yehao; Li, Yongchun; Hua, Xiaomei; Müller, Karin; Wang, Hailong; Yang, Tongyi; Wang, Qiong; Peng, Xin; Wang, Mengcheng; Pang, Yanjun; Qi, Jinliang; Yang, Yonghua

    2018-03-14

    Glyphosate is a non-selective organophosphate herbicide that is widely used in agriculture, but its effects on soil microbial communities are highly variable and often contradictory, especially for high dose applications. We applied glyphosate at two rates: the recommended rate of 50 mg active ingredient kg -1 soil and 10-fold this rate to simulate multiple glyphosate applications during a growing season. After 6 months, we investigated the effects on the composition of soil microbial community, the catabolic activity and the genetic diversity of the bacterial community using phospholipid fatty acids (PLFAs), community level catabolic profiles (CLCPs), and 16S rRNA denaturing gradient gel electrophoresis (DGGE). Microbial biomass carbon (C mic ) was reduced by 45%, and the numbers of the cultivable bacteria and fungi were decreased by 84 and 63%, respectively, under the higher glyphosate application rate. According to the PLFA analysis, the fungal biomass was reduced by 29% under both application rates. However, the CLCPs showed that the catabolic activity of the gram-negative (G-) bacterial community was significantly increased under the high glyphosate application rate. Furthermore, the DGGE analysis indicated that the bacterial community in the soil that had received the high glyphosate application rate was dominated by G- bacteria. Real-time PCR results suggested that copies of the glyphosate tolerance gene (EPSPS) increased significantly in the treatment with the high glyphosate application rate. Our results indicated that fungi were impaired through glyphosate while G- bacteria played an important role in the tolerance of microbiota to glyphosate applications.

  3. Quantitative Real-time PCR detection of putrescine-producing Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Kristýna Maršálková

    2017-01-01

    Full Text Available Biogenic amines are indispensable components of living cells; nevertheless these compounds could be toxic for human health in higher concentrations. Putrescine is supposed to be the major biogenic amine associated with microbial food spoilage. Development of reliable, fast and culture-independent molecular methods to detect bacteria producing biogenic amines deserves the attention, especially of the food industry in purpose to protect health. The objective of this study was to verify the newly designed primer sets for detection of two inducible genes adiA and speF together in Salmonella enterica and Escherichia coli genome by Real-time PCR. These forenamed genes encode enzymes in the metabolic pathway which leads to production of putrescine in Gram-negative bacteria. Moreover, relative expression of these genes was studied in E. coli CCM 3954 strain using Real-time PCR. In this study, sets of new primers for the detection two inducible genes (speF and adiA in Salmonella enterica and E. coli by Real-time PCR were designed and tested. Amplification efficiency of a Real-time PCR was calculated from the slope of the standard curves (adiA, speF, gapA. An efficiency in a range from 95 to 105 % for all tested reactions was achieved. The gene expression (R of adiA and speF genes in E. coli was varied depending on culture conditions. The highest gene expression of adiA and speF was observed at 6, 24 and 36 h (RadiA ~ 3, 5, 9; RspeF ~11, 10, 9; respectively after initiation of growth of this bacteria in nutrient broth medium enchired with amino acids. The results show that these primers could be used for relative quantification analysis of E. coli.

  4. Bio sorption of some Rare Earth Elements and Yttrium by Gram Positive and Gram Negative Bacteria

    International Nuclear Information System (INIS)

    Ibrahim, H.A.

    2012-01-01

    The separate bio sorption of the REEs La, Sm, Eu and Dy together with yttrium upon the Gram positive bacteria Bacillus subtilis (B.subtilis) and Bacillus Licheniformis (B. Licheniformis),the Gram negative bacterium Escherichia coli (E. coli ) and Saccharomyces cervisiae (Yeast) was studied. The revelant factors of ph 1-6, contact time (30-180 min), the initial rare earth concentration (50-200 mg/l) have been studied. The amount of the accumulated element was strongly affected by its concentration.In addition, bio sorptive fractionation of Y and the studied REEs from a solution containing a mixture of these elements was also studied. From the obtained data, it was found that Langmuir isotherm model for both B.licheniformis and E.coli gives a best fit for the studied elements over the working range of concentration (50-200 mg/I). Transmission electron microscopy exhibited accumulation throughout the bacterial cell with some granular deposits in both the cell periphery and cytoplasm

  5. Investigational drugs for the treatment of infections caused by multidrug-resistant Gram-negative bacteria.

    Science.gov (United States)

    Avery, Lindsay M; Nicolau, David P

    2018-04-01

    Infections caused by multidrug-resistant Gram-negative bacteria (MDR-GNB) are associated with significant mortality and costs. New drugs in development to combat these difficult-to-treat infections primarily target carbapenem-resistant Enterobacteriaceae, MDR Pseudomonas aeruginosa, and MDR Acinetobacter baumannii. Areas covered: The authors summarize in vitro and in vivo efficacy studies, as well as available clinical trial findings, for new agents in development for treatment of infection caused by MDR-GNB. Information regarding dosage regimens utilized in clinical trials and key pharmacokinetic and pharmacodynamic considerations are provided if available. A summary of recently approved agents, delafloxacin and meropenem/vaborbactam, is also included. Expert opinion: The development of multiple novel agents to fight MDR-GNB is promising to help save the lives of patients who acquire infection, and judicious use of these agents is imperative once they come to market to prevent the development of resistance. The other component paramount to this field of research is implementation of effective infection control policies and carbapenem-resistant Enterobacteriaceae (CRE) carrier screening protocols to mitigate the worldwide spread of MDR-GNB. Further investigation of anti-infective synergistic combinations will also be important, as well as support for economic research to reveal the true cost-benefit of utilization of the new agents discussed herein.

  6. The attenuation effect of UVc radiation doses in gram-negative bacteria (Brucella, Yersinia, Escherichia coli)

    International Nuclear Information System (INIS)

    Al-Mariri, A.

    2006-06-01

    The gram-negative bacteria Yersinia enterocolitica sero group O:3 and O:9, and Brucella (Melitensis and abortus) together with Escherichia coli (O:157, DH5α-pEt15b), were investigated to evaluate their susceptibility to UV radiation at 254 nm. If the dose of UVc was 18.7 mW/cm 2 , the time required for inactivation of Y. enterocolitica and E. coli DH5α-pEt15b and O:157 was 240s and 360s in the dark and light respectively; where if the dose was 19.5 mW/cm 2 , the time required was 60s in the dark and 120s in light respectively. The time required for inactivation of Brucella strains (melitensis and abortus) if the dose was 18.7 mW/cm 2 was 240s in both dark and light, whereas it was 120s(dark) and 240s (light) respectively, when the dose was 19.5 mW/cm 2 . Using E. coli O:157 as control, it appears that Y. enterocolitica sero group O:3 and O:9 and vaccinal strains of Brucella (Rev. 1 and S19) are more sensitive to UV than wild Brucella strains. No relation was found between the sensitivity of Y. enterocolitica to UV and the presence or absence of a pYV + virulence plasmid. (author)

  7. Functional characterization of Gram-negative bacteria from different genera as multiplex cadmium biosensors.

    Science.gov (United States)

    Bereza-Malcolm, Lara; Aracic, Sanja; Kannan, Ruban; Mann, Gülay; Franks, Ashley E

    2017-08-15

    Widespread presence of cadmium in soil and water systems is a consequence of industrial and agricultural processes. Subsequent accumulation of cadmium in food and drinking water can result in accidental consumption of dangerous concentrations. As such, cadmium environmental contamination poses a significant threat to human health. Development of microbial biosensors, as a novel alternative method for in situ cadmium detection, may reduce human exposure by complementing traditional analytical methods. In this study, a multiplex cadmium biosensing construct was assembled by cloning a single-output cadmium biosensor element, cadRgfp, and a constitutively expressed mrfp1 onto a broad-host range vector. Incorporation of the duplex fluorescent output [green and red fluorescence proteins] allowed measurement of biosensor functionality and viability. The biosensor construct was tested in several Gram-negative bacteria including Pseudomonas, Shewanella and Enterobacter. The multiplex cadmium biosensors were responsive to cadmium concentrations ranging from 0.01 to 10µgml -1 , as well as several other heavy metals, including arsenic, mercury and lead at similar concentrations. The biosensors were also responsive within 20-40min following exposure to 3µgml -1 cadmium. This study highlights the importance of testing biosensor constructs, developed using synthetic biology principles, in different bacterial genera. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The attenuation effect of UVc radiation doses in gram-negative bacteria (Brucella, Yersinia, Escherichia coli)

    International Nuclear Information System (INIS)

    Al-Mariri, A.

    2007-01-01

    The gram-negative bacteria Yersinia enterocolitica sero group O:3 and O:9, and Brucella (Melitensis and abortus) together with Escherichia coli (O:157, DH5alpha-pEt15b), were investigated to evaluate their susceptibility to UV radiation at 254 nm. If the dose of UVc was 18.7 mW/cm2, the time required for inactivation of Y. enterocolitica and E. coli DH5alpha-pEt15b and O:157 was 240s and 360s in the dark and light respectively. Where if the dose was 19.5 mW/cm2, the time required was 60s in the dark and 120s in light respectively. The time required for inactivation of Brucella strains (melitensis and abortus) if the dose was 18.7 mW/cm2 was 240s in both dark and light, whereas it was 120s (dark) and 240s (light) respectively, when the dose was 19.5 mW/cm2. Using E. coli O:157 as control, it appears that Y. enterocolitica sero group O:3 and O:9 and vaccinal strains of Brucella (Rev. 1 and S19) are more sensitive to UV than wild Brucella strains. No relation was found between the sensitivity of Y. enterocolitica to UV and the presence or absence of a pYV+ virulence plasmid. (author)

  9. Computational prediction of type III and IV secreted effectors in Gram-negative bacteria

    Energy Technology Data Exchange (ETDEWEB)

    McDermott, Jason E.; Corrigan, Abigail L.; Peterson, Elena S.; Oehmen, Christopher S.; Niemann, George; Cambronne, Eric; Sharp, Danna; Adkins, Joshua N.; Samudrala, Ram; Heffron, Fred

    2011-01-01

    In this review, we provide an overview of the methods employed by four recent papers that described novel methods for computational prediction of secreted effectors from type III and IV secretion systems in Gram-negative bacteria. The results of the studies in terms of performance at accurately predicting secreted effectors and similarities found between secretion signals that may reflect biologically relevant features for recognition. We discuss the web-based tools for secreted effector prediction described in these studies and announce the availability of our tool, the SIEVEserver (http://www.biopilot.org). Finally, we assess the accuracy of the three type III effector prediction methods on a small set of proteins not known prior to the development of these tools that we have recently discovered and validated using both experimental and computational approaches. Our comparison shows that all methods use similar approaches and, in general arrive at similar conclusions. We discuss the possibility of an order-dependent motif in the secretion signal, which was a point of disagreement in the studies. Our results show that there may be classes of effectors in which the signal has a loosely defined motif, and others in which secretion is dependent only on compositional biases. Computational prediction of secreted effectors from protein sequences represents an important step toward better understanding the interaction between pathogens and hosts.

  10. Antimicrobial Activity of Ephedra pachyclada Methanol Extract on Some Enteric Gram Negative Bacteria Which Causes Nosocomial Infections by Agar Dilution Method

    Directory of Open Access Journals (Sweden)

    Amin Sadeghi Dosari

    2016-10-01

    Full Text Available Background Past history indicates that plants were served as an important source of medicine. Otherwise, in developing countries people use medicinal plants against infectious disease because they cannot afford expensive drugs. Due to increasing rate of drug-resistant diseases, there is an urgent need to detect novel antimicrobial compounds from medicinal plants. Objectives The aim of the present study was to determine Antimicrobial activity of Ephedra pachyclada methanol extract on some enteric Gram-negative bacteria which causes nosocomial infections by agar dilution method. Methods In this cross-sectional study, in order to examine the antimicrobial effects of Ephedra pachyclada extract on intestinal Gram-negative bacteria, we exposed them to 0/128, 0/25, 0/5, 1, 2, 4 and 8 mg/mL of the extract. Ephedra pachyclada was collected from Jiroft Heights and methanolic extract was prepared with maceration method, during which, 50 gr powder of Ephedra pachyclada was dissolved in 300 mL of 80% methanol. Results In this study, the antibacterial effects of Ephedra pachyclada extract on Gram-negative bacteria such as Pseudomonas aeruginosa, Escherichia coli (PTCC-O157, Escherichia coli (ATCC-25922, Klebsiella pnemoniae, Serratia marcescens was investigated, defining the minimum inhibitory concentration (MIC by agar dilution method. It has been demonstrated that methanolic extract of Ephedra pachyclada affect intestinal Gram-negative bacteria. Conclusions The result showed that, Ephedra pachyclada extract has effective antimicrobial ingredients which are cheap and readily available. It can be used for medicinal purposes in the production of antimicrobial drug.

  11. Removal of bowel aerobic gram-negative bacteria is more effective than immunosuppression with cyclophosphamide and steroids to decrease natural alpha-galactosyl IgG antibodies.

    Science.gov (United States)

    Mañez, R; Blanco, F J; Díaz, I; Centeno, A; Lopez-Pelaez, E; Hermida, M; Davies, H F; Katopodis, A

    2001-02-01

    Natural alpha-Galactosyl (Gal) antibodies play an important role in the rejection of pig xenografts by humans and Old World monkeys. In this study we investigate the efficacy of two different strategies to reduce the serum level of natural anti-Gal antibodies. On the one hand, removal of aerobic gram-negative bacteria from the intestinal flora, because anti-Gal antibodies appear to be produced as a result of the continuous sensitization by these microorganisms. On the other hand, we studied the effect on these antibodies of an immunosuppressive regimen of cyclophosphamide and steroids. Ten baboons were treated for three months with norfloxacin (Nor Group; n=6) or cyclophosphamide and steroids (CyP Group; n=4). A further four baboons did not receive any treatment (Control Group). Aerobic gram-negative bacteria became negative in stools of the Nor Group after two weeks of treatment, and remained undetectable until week 7. Thereafter, a gradual increase on the fecal concentration of aerobic gram-negative bacteria was observed despite the norfloxacin treatment. The mean anti-Gal IgG in the Nor Group gradually declined from week 4 to 9 to a mean of 62.7 +/- 18% of the baseline level, and during this period were significantly lower than in the CyP (Premoval of normal aerobic gram-negative bacteria from the intestinal flora is more effective than immunosuppression with CyP and steroids in reducing the level of natural anti-Gal antibodies, although there is no discernible effect on IgM antibodies.

  12. Bacteriological Assessment of Pneumonia Caused by Gram-Negative Bacteria in Patients Hospitalized in Intensive Care Unit.

    Science.gov (United States)

    Guzek, A; Korzeniewski, K; Tomaszewski, D; Rybicki, Z; Zwolińska, E

    2017-01-01

    The article presents the results of 11-year study (2005-2015) of Gram-negative bacteria responsible for pneumonia in 2033 mechanically ventilated patients hospitalized in Intensive Care Unit. Of 8796 biological samples, consisting mainly of bronchial aspirate (97.9 %), 2056 bacterial strains were isolated and subjected to identification. VITEK 2 was used to determine drug susceptibility (classified according to the EUCAST criteria). ESBL, MBL and KPC-producing strains were identified by means of phenotypic methods using appropriate discs. The findings were that the predominant bacteria responsible for infections consisted of Enterobacteriaceae (42.0 %), Acinetobacter baumannii (37.2 %), Pseudomonas aeruginosa (16.1 %), and Stenotrophomonas maltophila (4.7 %). We observed a rise in the number of bacteria causing pneumonia throughout the study period, especially in S. maltophila and Enterobacteriaceae ESBL (+). Gram-negative bacilli were 100 % susceptible to colistin, apart from naturally resistant strains such as Proteus mirabilis, Serratia marcescens, whereas Enterobacteriaceae ESBL (+) were susceptible to imipenem and meropenem. Acinetobacter baumannii strains exhibited the lowest drug susceptibility. In conclusion, we report an increase in the prevalence of pneumonia associated with Gram-negative bacteria in mechanically ventilated intensive care patients. Colistin remains the most effective drug against the majority of Gram-negative bacteria. Therapeutic problems are common in the course of treatment of Acinetobacter baumannii infections.

  13. Novel touchdown-PCR method for the detection of putrescine producing gram-negative bacteria in food products.

    Science.gov (United States)

    Wunderlichová, Leona; Buňková, Leona; Koutný, Marek; Valenta, Tomáš; Buňka, František

    2013-06-01

    Formation of biogenic amines may occur in food due to metabolic activities of contaminating Gram-negative bacteria. Putrescine is assumed to be the major biogenic amine associated with microbial food spoilage. Gram-negative bacteria can form putrescine by three metabolic pathways that can include eight different enzymes. The objective of this study was to design new sets of primers able to detect all important enzymes involved in the production of putrescine by Gram-negative bacteria. Seven new sets of consensual primers based on gene sequences of different bacteria were designed and used for detection of the speA, adiA, adi, speB, aguA, speC, and speF genes. A newly developed touchdown polymerase chain reaction (PCR) method using these primers was successfully applied on several putrescine-producers. Selected PCR products were sequenced and high similarity of their sequences (99-91%) with known sequences of the corresponding genes confirmed high specificity of the developed sets of primers. Furthermore, all the investigated bacteria produced both putrescine and agmatine, an intermediate of putrescine production, which was confirmed by chemical analysis. The developed new touchdown PCR method could easily be used to detect potential foodborne Gram-negative producers of putrescine. The newly developed sets of primers could also be useful in further research on putrescine metabolism in contaminating microbiota. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Rapid photokilling of gram-negative Escherichia coli bacteria by platinum dispersed titania nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Bonamali, E-mail: bpal@thapar.edu [School of Chemistry and Biochemistry, Thapar University, Patiala 147004 (India); Singh, Isha; Angrish, Kunal; Aminedi, Raghavendra; Das, Niranjan [Department of Biotechnology and Environmental Sciences, Thapar University, Patiala 147004 (India)

    2012-09-14

    Superior antimicrobial activity of 2 wt.% Pt-dispersed TiO{sub 2} thin film was observed in photokilling Gram-negative Escherichia coli bacteria within 5 min irradiation (640 {mu}W cm{sup -2}, {lambda} > 340 nm) from UV torch than bare TiO{sub 2} film. Severe disruption of cell membrane has occurred over illuminated Pt-TiO{sub 2} catalysts films coated with 100-300 {mu}g powders per 5 cm{sup 2} areas over sterilized glass slides. The Pt dispersion onto TiO{sub 2} by impregnation-hydrogen reduction always exhibited better photokilling effect than Pt photodeposition, irrespective of Pt-TiO{sub 2} dose and light exposure time. Similar trend in photoactivity difference between two Pt-TiO{sub 2} catalysts is also observed in aqueous slurry because of the unlike surface structure of TiO{sub 2} due to different annealing temperatures, size and nature of Pt particles dispersion onto TiO{sub 2} photocatalysts. -- Graphical abstract: Platinization of TiO{sub 2} by impregnation-hydrogen reduction method exhibited drastic photoetching and killing of E. coli bacteria over UV-irradiated catalysts films in comparison to Pt photodeposition. Highlights: Black-Right-Pointing-Pointer Remarkable antimicrobial activity of photorradiated Pt-TiO{sub 2} coated thin film. Black-Right-Pointing-Pointer Pt impregnation-exhibits superior photoactivity than Pt photodeposition onto TiO{sub 2}. Black-Right-Pointing-Pointer Photokilling of E. coli cells occur within 10 min of UV (640 {mu}W cm{sup -2}) irradiation. Black-Right-Pointing-Pointer Size and nature of Pt deposition control the bactericidal effect of TiO{sub 2} catalyst. Black-Right-Pointing-Pointer Photodissolution of bacterial surface is occurred on prolong UV light exposure.

  15. Rapid method for the differentiation of gram-positive and gram-negative bacteria on membrane filters.

    OpenAIRE

    Romero, S; Schell, R F; Pennell, D R

    1988-01-01

    Microfiltration has become a popular procedure for the concentration and enumeration of bacteria. We developed a rapid and sensitive method for the differentiation of gram-positive and gram-negative bacteria, utilizing a polycarbonate membrane filter, crystal violet, iodine, 95% ethanol, and 6% carbol fuchsin, that can be completed in 60 to 90 s. Gram reactions of 49 species belonging to 30 genera of bacteria were correctly determined by the filter-Gram stain. The sensitivities of the filter-...

  16. Serum amyloid P component bound to gram-negative bacteria prevents lipopolysaccharide-mediated classical pathway complement activation

    NARCIS (Netherlands)

    de Haas, C. J.; van Leeuwen, E. M.; van Bommel, T.; Verhoef, J.; van Kessel, K. P.; van Strijp, J. A.

    2000-01-01

    Although serum amyloid P component (SAP) is known to bind many ligands, its biological function is not yet clear. Recently, it was demonstrated that SAP binds to lipopolysaccharide (LPS). In the present study, SAP was shown to bind to gram-negative bacteria expressing short types of LPS or

  17. Serum amyloid P component bound to gram-negative bacteria prevents lipopolysaccharide-mediated classical pathway complement activation

    NARCIS (Netherlands)

    de Haas, CJC; van Leeuwen, EMM; van Bommel, T; Verhoef, J; van Kessel, KPM; van Strijp, JAG

    Although serum amyloid P component (SAP) is known to bind many ligands, its biological function is not yet clear. Recently, it was demonstrated that SAP binds to lipopolysaccharide (LPS), In the present study, SAP was shown to bind to gram-negative bacteria expressing short types of LPS or

  18. Comparing the harmful effects of nontuberculous mycobacteria and Gram negative bacteria on lung function in patients with cystic fibrosis

    DEFF Research Database (Denmark)

    Qvist, Tavs; Taylor-Robinson, David; Waldmann, Elisabeth

    2015-01-01

    BACKGROUND: To better understand the relative effects of infection with nontuberculous mycobacteria and Gram negative bacteria on lung function decline in cystic fibrosis, we assessed the impact of each infection in a Danish setting. METHODS: Longitudinal registry study of 432 patients with cystic...

  19. Bloodstream infections in pediatric patients with acute leukemia: Emphasis on gram-negative bacteria infections.

    Science.gov (United States)

    Kuo, Fu-Chun; Wang, Shih-Min; Shen, Ching-Fen; Ma, Yun-Ju; Ho, Tzong-Shiann; Chen, Jiann-Shiuh; Cheng, Chao-Neng; Liu, Ching-Chuan

    2017-08-01

    Acute leukemia is the most common pediatric hematological malignancy. Bloodstream infections (BSIs) are severe complications in these patients during chemotherapy. This study aims to explore clinical features, laboratory, and microbiological characteristics of BSIs in acute leukemic children. Patients aged leukemia or acute lymphocytic leukemia with BSIs from January 2004 to December 2013 were enrolled. BSIs was defined as positive isolate(s) of blood culture and associated with clinical findings. Clinical presentations, demographic features, and microbiological findings were retrospectively reviewed. In total, 126 isolates of 115 episodes of BSIs were identified from 69 patients (acute lymphocytic leukemia 56; acute myeloid leukemia 13). Gram-negative bacteria (GNB), gram-positive cocci, and fungi constituted 56.3%, 42.3%, and 2.4% of the pathogens, respectively. Eighty-three and a half percent of BSIs occurred along with neutropenia, and 73% had severe neutropenia. GNB was the leading pathogen of BSIs. The major GNBs were Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa. White blood cell counts, absolute neutrophil counts, and platelet counts were significantly lower in patients of BSIs caused by GNB than gram-positive cocci. Plasma level of C-reactive protein was significant high in patients of GNB BSIs (179.8 mg/L vs. 127.2 mg/L; p = 0.005). Eighty-two percent of patients of E. coli, K. pneumonia, and P. aeruginosa BSIs had sepsis related organ failure or organ dysfunction. P. aeruginosa BSIs had the highest case-mortality (40%). Neutropenia was the major risk factor of BSIs in pediatric leukemic patients. BSIs of GNB were associated with severe neutropenia, systemic inflammatory responses, and high mortality. Copyright © 2015. Published by Elsevier B.V.

  20. Infections Caused by Antimicrobial Drug-Resistant Saprophytic Gram-Negative Bacteria in the Environment.

    Science.gov (United States)

    Raphael, Eva; Riley, Lee W

    2017-01-01

    Drug-resistance genes found in human bacterial pathogens are increasingly recognized in saprophytic Gram-negative bacteria (GNB) from environmental sources. The clinical implication of such environmental GNBs is unknown. We conducted a systematic review to determine how often such saprophytic GNBs cause human infections. We queried PubMed for articles published in English, Spanish, and French between January 2006 and July 2014 for 20 common environmental saprophytic GNB species, using search terms "infections," "human infections," "hospital infection." We analyzed 251 of 1,275 non-duplicate publications that satisfied our selection criteria. Saprophytes implicated in blood stream infection (BSI), urinary tract infection (UTI), skin and soft tissue infection (SSTI), post-surgical infection (PSI), osteomyelitis (Osteo), and pneumonia (PNA) were quantitatively assessed. Thirteen of the 20 queried GNB saprophytic species were implicated in 674 distinct infection episodes from 45 countries. The most common species included Enterobacter aerogenes, Pantoea agglomerans , and Pseudomonas putida . Of these infections, 443 (66%) had BSI, 48 (7%) had SSTI, 36 (5%) had UTI, 28 (4%) had PSI, 21 (3%) had PNA, 16 (3%) had Osteo, and 82 (12%) had other infections. Nearly all infections occurred in subjects with comorbidities. Resistant strains harbored extended-spectrum beta-lactamase (ESBL), carbapenemase, and metallo-β-lactamase genes recognized in human pathogens. These observations show that saprophytic GNB organisms that harbor recognized drug-resistance genes cause a wide spectrum of infections, especially as opportunistic pathogens. Such GNB saprophytes may become increasingly more common in healthcare settings, as has already been observed with other environmental GNBs such as Acinetobacter baumannii and Pseudomonas aeruginosa .

  1. Infections Caused by Antimicrobial Drug-Resistant Saprophytic Gram-Negative Bacteria in the Environment

    Directory of Open Access Journals (Sweden)

    Eva Raphael

    2017-10-01

    Full Text Available BackgroundDrug-resistance genes found in human bacterial pathogens are increasingly recognized in saprophytic Gram-negative bacteria (GNB from environmental sources. The clinical implication of such environmental GNBs is unknown.ObjectivesWe conducted a systematic review to determine how often such saprophytic GNBs cause human infections.MethodsWe queried PubMed for articles published in English, Spanish, and French between January 2006 and July 2014 for 20 common environmental saprophytic GNB species, using search terms “infections,” “human infections,” “hospital infection.” We analyzed 251 of 1,275 non-duplicate publications that satisfied our selection criteria. Saprophytes implicated in blood stream infection (BSI, urinary tract infection (UTI, skin and soft tissue infection (SSTI, post-surgical infection (PSI, osteomyelitis (Osteo, and pneumonia (PNA were quantitatively assessed.ResultsThirteen of the 20 queried GNB saprophytic species were implicated in 674 distinct infection episodes from 45 countries. The most common species included Enterobacter aerogenes, Pantoea agglomerans, and Pseudomonas putida. Of these infections, 443 (66% had BSI, 48 (7% had SSTI, 36 (5% had UTI, 28 (4% had PSI, 21 (3% had PNA, 16 (3% had Osteo, and 82 (12% had other infections. Nearly all infections occurred in subjects with comorbidities. Resistant strains harbored extended-spectrum beta-lactamase (ESBL, carbapenemase, and metallo-β-lactamase genes recognized in human pathogens.ConclusionThese observations show that saprophytic GNB organisms that harbor recognized drug-resistance genes cause a wide spectrum of infections, especially as opportunistic pathogens. Such GNB saprophytes may become increasingly more common in healthcare settings, as has already been observed with other environmental GNBs such as Acinetobacter baumannii and Pseudomonas aeruginosa.

  2. Role of Gram-Negative Bacteria and Their Endotoxins in Rat Death after Heat Stress,

    Science.gov (United States)

    1981-02-26

    small volume (0.05 ml) of the homogenate on selective ( MacConkey , Difco, Detroit, MI) and non-selective (5% sheep blood agar) plating media. In...homogenates. Gram-negative bacterial count per gram of duodenal sample was determined from colony counts made from 5 replicate MacConkey plates prepared from

  3. Activation of toll-like receptors 2 and 4 by gram-negative periodontal bacteria

    NARCIS (Netherlands)

    Kikkert, R.; Laine, M. L.; Aarden, L. A.; van Winkelhoff, A. J.

    2007-01-01

    BACKGROUND/AIMS: Periodontitis is a chronic infectious disease associated with a gram-negative subgingival microflora. Bacterial components stimulate, among other receptors, Toll-like receptor (TLR) 2 and/or TLR4. Accumulating evidence indicates that both qualitatively and quantitatively distinct

  4. Vitreous System Ag2O –ZnO–B2O3 Action Against Gram Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Razvan Stefan

    2010-05-01

    Full Text Available In this work the ability of the system xAg2O  (100-x [45ZnO55B2O3] oxide glasses to inhibit the growth of bacteria Eschierchia coli, Pseudomonas and Salmonella was investigated. Using the diffusimetric method there were measured the diameters of inhibition, in order to classify the sensitivity of gram negative bacteria to oxide compounds containing silver, for their use as filters. Vitreous samples were processed as powders with grain between 45 and 75 m and less than 45 m for a large of contact area with the microorgansms and to make possible the study of biological effect of grain addiction. Action of the investigated oxide system against the gram negative bacteria is strictly related to the presence of silver oxide in glass composition.

  5. A chromatographic approach to distinguish Gram-positive from Gram-negative bacteria using exogenous volatile organic compound metabolites.

    Science.gov (United States)

    Ramírez-Guízar, Susana; Sykes, Hannah; Perry, John D; Schwalbe, Edward C; Stanforth, Stephen P; Perez-Perez, Ma Cristina I; Dean, John R

    2017-06-09

    This paper utilized L-alanine aminopeptidase activity as a useful approach to distinguish between Gram-negative and Gram-positive bacteria. This was done using two enzyme substrates, specifically 2-amino-N-phenylpropanamide and 2-amino-N-(4-methylphenyl)propanamide which liberated the volatile compounds aniline and p-toluidine, respectively. Two complementary analytical techniques have been used to identify and quantify the VOCs, specifically static headspace multicapillary column gas chromatography ion mobility spectrometry (SHS-MCC-GC-IMS) and headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS). Superior limits of detection were obtained using HS-SPME-GC-MS, typically by a factor of x6 such that the LOD for aniline was 0.02μg/mL and 0.01μg/mL for p-toluidine. In addition, it was also possible to determine indole interference-free by HS-SPME-GC-MS at an LOD of 0.01μg/mL. The approach was applied to a range of selected bacteria: 15 Gram-negative and 7 Gram-positive bacteria. Use of pattern recognition, in the form of Principal Component Analysis, confirmed that it is possible to differentiate between Gram-positive and Gram-negative bacteria using the enzyme generated VOCs, aniline and p-toluidine. The exception was Stenotrophomonas maltophilia which showed negligible VOC concentrations for both aniline and p-toluidine, irrespective of the analytical techniques used and hence was not characteristic of the other Gram-negative bacteria investigated. The developed methodology has the potential to be applied for clinical and food applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Mechanism of decreased susceptibility for Gram-negative bacteria and synergistic effect with ampicillin of indole-3-carbinol.

    Science.gov (United States)

    Sung, Woo Sang; Lee, Dong Gun

    2008-09-01

    Indole-3-carbinol (I3C) is a natural compound found in a wide variety of plant food substances including members of the family Cruciferae with antioxidant and potential chemopreventive properties. In a previous study, I3C exhibited broad spectrum antibacterial activities. Particularly, it showed a more potent antibacterial activity against Gram-positive bacteria than Gram-negative bacteria. To elucidate this disparity of antibacterial activity between Gram-positive and Gram-negative bacteria, we investigated the actions of the efflux pumps and the lipopolysaccharide (LPS) barrier of the outer membrane of Gram-negative bacteria. The results showed that the antibacterial activity of I3C was affected by the barrier action of LPS in the outer membrane rather than by the efflux pumps. To assess its potential for combination therapy in treating bacterial infections, we investigated its synergy effects in combination with conventional antibiotics. The results demonstrated that I3C showed considerable synergistic activity in combination with ampicillin against drug-resistant isolates.

  7. Sensing the enemy within: how macrophages detect intracellular Gram-negative bacteria

    OpenAIRE

    Demon, Dieter; Vande Walle, Lieselotte; Lamkanfi, Mohamed

    2014-01-01

    Caspase-11 contributes to host defense against Gram-negative bacterial pathogens by inducing an inflammatory form of programmed cell death in infected cells. Lipopolysaccharides (LPS) have been identified as the microbial agents that stimulate caspase-11 activation; however, the mechanism of LPS detection has been unknown. In a recent study, Shao and colleagues demonstrate that caspase-11 and its human homologues, caspases -4 and -5, unexpectedly act as direct sensors of cytosolic LPS.

  8. Inhibition of Multidrug-Resistant Gram-Positive and Gram-Negative Bacteria by a Photoactivated Porphyrin.

    Science.gov (United States)

    Bondi, Moreno; Mazzini, Anna; de Niederhäusern, Simona; Iseppi, Ramona; Messi, Patrizia

    2017-12-04

    The authors studied the in vitro antibacterial activity of the photo-activated porphyrin meso-tri(N-methyl-pyridyl), mono(N-tetradecyl-pyridyl)porphine (C14) against four multidrug-resistant bacteria: Staphylococcus aureus, Enterococcus faecalis (Gram-positive), Escherichia coli, Pseudomonas aeruginosa (Gram-negative). Using 10 μg/ml of porphyrin and 60 sec irradiation we observed the remarkable susceptibility of S. aureus and E. faecalis to treatment while, under the same conditions, E. coli and P. aeruginosa showed very low susceptibility. In a later stage, suspensions of Gram-negative bacteria were processed with EDTA before photo-activation, obtaining a significant decrease in viable counts. In view of the results, if the combination of low porphyrin concentrations and short irradiation times will be effective in vivo also, this approach could be a possible alternative to antibiotics, in particular against localized infections due to multidrug-resistant microorganisms.

  9. Gram-negative bacteria account for main differences between faecal microbiota from patients with ulcerative colitis and healthy controls

    DEFF Research Database (Denmark)

    Vigsnæs, Louise Kristine; Brynskov, J.; Steenholdt, C.

    2012-01-01

    Detailed knowledge about the composition of the intestinal microbiota may be critical to unravel the pathogenesis of ulcerative colitis (UC), a human chronic inflammatory bowel disease, since the intestinal microbes are expected to influence some of the key mechanisms involved in the inflammatory...... that the microbiota in UC patients with active disease differ from that in healthy controls. Our findings indicate that alterations in the composition of the Gram-negative bacterial population, as well as reduced numbers of lactobacilli and A. muciniphila may play a role in UC....

  10. Antibacterial activity and interactions of plant essential oil combinations against Gram-positive and Gram-negative bacteria

    OpenAIRE

    Cristina Anamaria Semeniuc; Carmen Rodica Pop; Ancuţa Mihaela Rotar

    2017-01-01

    The aim of this study was to compare the antibacterial effects of several essential oils (EOs) alone and in combination against different Gram-positive and Gram-negative bacteria associated with food products. Parsley, lovage, basil, and thyme EOs, as well as their mixtures (1:1, v/v), were tested against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhimurium. The inhibitory effects ranged from strong (thyme EO against E. coli) to no inhib...

  11. Distribution of plasmid-mediated quinolone resistance in Gram-negative bacteria from a tertiary hospital in Nigeria.

    Science.gov (United States)

    Ogbolu, David Olusoga; Alli, Armstrong Oyebode; Anorue, Michael C; Daini, Oluwole Adebayo; Oluwadun, Afolabi

    2016-01-01

    Until recently, mechanisms of resistance to quinolones in Gram-negative bacteria were believed to be only chromosome encoded. However, emergence of plasmid-mediated quinolone resistance (PMQR) has been reported worldwide. This study investigated distribution of PMQR in Gram-negative bacteria from a tertiary hospital in eastern part of Nigeria. Seventy-one nonduplicate Gram-negative bacterial isolates of eight species were analyzed for antimicrobial susceptibility, genotypic detection of various PMQRs, typed by random amplified polymorphic DNA (RAPD) and analysis of plasmids present, including replicon typing. The minimum inhibitory concentrations showed MIC90values as high as 256 μg/ml for fluoroquinolones. Carriage of PMQR was found to be 35.2%. Twenty (28.2%) isolates carried various qnr genes, of which seven (9.9%) qnrA1; four (5.6%) qnrB1; eight (11.3%) qnrS1 while one (1.4%) encoded qnrD1. Eighteen (25.4%) isolates were positive for aac(6')-Ib-cr while carriage of multiple genes exists in some strains. Similarly, 13 isolates (18.7%) were found to carry PMQR efflux pump gene, qepA. Conjugation experiments revealed that the plasmids once transferred coded for fluoroquinolone resistance. The transconjugant strains carried a common plasmid estimated to be 65 kb. These plasmids were untypable for replicon/incompatibility. Typing revealed high diversity among all species tested with no identical RAPD pattern seen. This study further confirms high level resistance to many antimicrobials in different species of Gram-negative bacteria including fluoroquinolones and spread of PMQR genes in Southern Nigeria.

  12. Sensing the enemy within: how macrophages detect intracellular Gram-negative bacteria.

    Science.gov (United States)

    Demon, Dieter; Vande Walle, Lieselotte; Lamkanfi, Mohamed

    2014-12-01

    Caspase-11 contributes to host defense against Gram-negative bacterial pathogens by inducing an inflammatory form of programmed cell death in infected cells. Lipopolysaccharides (LPS) have been identified as the microbial agents that stimulate caspase-11 activation; however, the mechanism of LPS detection has been unknown. In a recent study, Shao and colleagues demonstrate that caspase-11 and its human homologues, caspases -4 and -5, unexpectedly act as direct sensors of cytosolic LPS. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria

    Science.gov (United States)

    Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Yadav, Anand

    2013-01-01

    Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50 μL leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3 mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0 mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties. PMID:24223039

  14. Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria.

    Science.gov (United States)

    Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Daniels, Dwayne; Yadav, Anand

    2013-01-01

    Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50  μ L leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3 mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0 mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties.

  15. Gram negative bacteria are associated with the early stages of necrotizing enterocolitis.

    Directory of Open Access Journals (Sweden)

    Erica M Carlisle

    Full Text Available INTRODUCTION: Necrotizing enterocolitis (NEC affects 5-10% of infants born weighing less than 1500 g. Most models of NEC recapitulate late-stage disease with gut necrosis and elevated inflammatory mediators. Evaluation of NEC at earlier, less lethal stages of disease will allow investigation of initial disease triggers and may advance our understanding of temporal relationships between factors implicated in NEC pathogenesis. In this manuscript, we describe our investigation of early NEC and test the hypothesis that bacteria and inflammatory mediators differ between animals with early NEC and disease free animals. METHODS: On DOL7 C3HeB/FeJ pups were fed liquid formula with 1×10(4 Streptococcus thoraltensis, Serratia marcescens, and Pseudomonas aeruginosa every 3 h. To initiate NEC, pups underwent asphyxia (100% N(2 for 90 s and hypothermia (4°C for 10 min after feeding. Pups were euthanized at 72 h. Intestines were collected for histologic NEC scoring and DNA/RNA extraction. Bacterial populations were identified by 16S rRNA pyrosequencing and principal component analysis (PCA. RNA isolates underwent QRT-PCR for Toll-like Receptor 4 (TLR4 and inducible nitric oxide synthase (iNOS. RESULTS: Despite histologic, intestinal damage in mice with NEC, no gross necrosis was observed suggesting early disease. QRT-PCR yielded no difference between groups in TLR4 or iNOS mRNA levels. PCA demonstrated relative clustering of microbial communities based on presence or absence of NEC. 16S pyrosequencing demonstrated similar phyla between groups (Firmicutes and Proteobacteria predominated in all animals. However, the colonic microbiota of animals with NEC had more Citrobacter (p<0.01, Klebsiella (p<0.05, and Tatumella (p<0.05, while that of animals without NEC had more Streptococcus (p<0.01 and Enterococcus (p<0.01. CONCLUSION: Citrobacter, Klebsiella, and Tatumella are associated with NEC. Differential colonic bacteria were identified despite the lack of

  16. Dynamics of Gram-negative bacteria population density in a soil in the course of the succession initiated by chitin and cellulose

    Science.gov (United States)

    Konstantin, Ivanov; Lubov, Polyanskaya

    2014-05-01

    The functions of actinomycetes in polymer destruction in soil traditionally considered as the dominant, compare to another groups of bacteria. Gram-positive bacteria also have ecological functions in destruction of soil organic matter. The role of Gram-negative bacteria has been researched in the microbial succession in terms of polymers destruction, which are widely spreads in soils: chitin and cellulose. The method with nalidixic acid as an inhibitor of DNA division of Gram-negative bacteria was modified. By modified method microbial succession of Gram-negative bacteria in the different horizons of a chernozem under aerobic and anaerobic conditions was researched. Chitin and cellulose as the source of nutrients with moistening was used in experiments. The introduction of chitin had no positive effect on the population density of Gram-negative bacteria in a chernozem, but it advanced the date of their appearance in microbial succession: the maximum of Gram-negative bacteria population density was registered on the 3rd- 7th day of the experiment with adding chitin. Compare to the control, which one was without any nutrient adding this dynamics registered much earlier. Consequently, the introduction of chitin as an additional source of nutrition promoted revealing of the Gram-negative bacteria in soil already at the early stages of the succession. In the course of the succession, when the fungal mycelium begins to die off, the actinomycetic mycelium increases in length, i.e., Gram-negative bacteria are replaced at this stage with Gram-positive ones, the leading role among which belongs to actinomycetes. The growth rate of Gram-negative bacteria is higher than that of actinomycetes, so they start chitin utilization at the early stages of the succession, whereas actinomycetes dominate at the late stages. The population density of Gram-negative bacteria was lower under the anaerobic conditions as compared with that in the aerobic ones. The population density of Gram-negative

  17. Associations of Eu(III) with Gram-negative bacteria, Alcaligenes faecalis, Shewanella putrefaciens, and Paracoccus denitrificans

    International Nuclear Information System (INIS)

    Ozaki, Takuo; Ohnuki, Toshihiko; Kimura, Takaumi; Francis, Arokiasamy J.

    2005-01-01

    We studied the association of Eu(III) with Gram-negative bacteria, Alcaligenes faecalis, Shewanella putrefaciens, and Paracoccus denitrificans by a batch method and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The kinetics study showed that the Eu(III) adsorption on the bacteria rapidly proceeded. The Eu(III) adsorption on A. faecalis and P. denitrificans at pHs 3, 4, and 5, and that on S.putrefaciens at pHs 4 and 5 reached a maximum within 5 minutes after contact. For P. denitrificans, the percent adsorption of Eu(III) decreased after the maximum percent adsorption was attained, which suggests the existence of exudates with an affinity with Eu(III). TRLFS showed that the coordination of Eu(III) on these bacteria is multidentate through an inner-spherical process. The ligand field of Eu(III) on P. denitrificans was as strong as the ones observed for halophilic microorganisms, while that of A. faecalis and S. putrefaciens was the typical one observed for non-halophilic microorganisms. The coordination environment of Eu(III) on the bacteria differed from each other, though they are categorized as Gram-negative bacteria with the similar cell wall components. (author)

  18. Silver resistance in Gram-negative bacteria: a dissection of endogenous and exogenous mechanisms

    Science.gov (United States)

    Randall, Christopher P.; Gupta, Arya; Jackson, Nicole; Busse, David; O'Neill, Alex J.

    2015-01-01

    Objectives To gain a more detailed understanding of endogenous (mutational) and exogenous (horizontally acquired) resistance to silver in Gram-negative pathogens, with an emphasis on clarifying the genetic bases for resistance. Methods A suite of microbiological and molecular genetic techniques was employed to select and characterize endogenous and exogenous silver resistance in several Gram-negative species. Results In Escherichia coli, endogenous resistance arose after 6 days of exposure to silver, a consequence of two point mutations that were both necessary and sufficient for the phenotype. These mutations, in ompR and cusS, respectively conferred loss of the OmpC/F porins and derepression of the CusCFBA efflux transporter, both phenotypic changes previously linked to reduced intracellular accumulation of silver. Exogenous resistance involved derepression of the SilCFBA efflux transporter as a consequence of mutation in silS, but was additionally contingent on expression of the periplasmic silver-sequestration protein SilE. Silver resistance could be selected at high frequency (>10−9) from Enterobacteriaceae lacking OmpC/F porins or harbouring the sil operon and both endogenous and exogenous resistance were associated with modest fitness costs in vitro. Conclusions Both endogenous and exogenous silver resistance are dependent on the derepressed expression of closely related efflux transporters and are therefore mechanistically similar phenotypes. The ease with which silver resistance can become selected in some bacterial pathogens in vitro suggests that there would be benefit in improved surveillance for silver-resistant isolates in the clinic, along with greater control over use of silver-containing products, in order to best preserve the clinical utility of silver. PMID:25567964

  19. Benzyl isothiocyanate, a major component from the roots of Salvadora persica is highly active against Gram-negative bacteria.

    Directory of Open Access Journals (Sweden)

    Abier Sofrata

    Full Text Available Plants produce a number of antimicrobial substances and the roots of the shrub Salvadora persica have been demonstrated to possess antimicrobial activity. Sticks from the roots of S. persica, Miswak sticks, have been used for centuries as a traditional method of cleaning teeth. Diverging reports on the chemical nature and antimicrobial repertoire of the chewing sticks from S. persica led us to explore its antibacterial properties against a panel of pathogenic or commensal bacteria and to identify the antibacterial component/s by methodical chemical characterization. S. persica root essential oil was prepared by steam distillation and solid-phase microextraction was used to sample volatiles released from fresh root. The active compound was identified by gas chromatography-mass spectrometry and antibacterial assays. The antibacterial compound was isolated using medium-pressure liquid chromatography. Transmission electron microscopy was used to visualize the effect on bacterial cells. The main antibacterial component of both S. persica root extracts and volatiles was benzyl isothiocyanate. Root extracts as well as commercial synthetic benzyl isothiocyanate exhibited rapid and strong bactericidal effect against oral pathogens involved in periodontal disease as well as against other Gram-negative bacteria, while Gram-positive bacteria mainly displayed growth inhibition or remained unaffected. The short exposure needed to obtain bactericidal effect implies that the chewing sticks and the essential oil may have a specific role in treatment of periodontal disease in reducing Gram-negative periodontal pathogens. Our results indicate the need for further investigation into the mechanism of the specific killing of Gram-negative bacteria by S. persica root stick extracts and its active component benzyl isothiocyanate.

  20. Scavengers for bacteria: Rainbow trout have two functional variants of MARCO that bind to gram-negative and -positive bacteria.

    Science.gov (United States)

    Poynter, Sarah J; Monjo, Andrea L; Micheli, Gabriella; DeWitte-Orr, Stephanie J

    2017-12-01

    Class A scavenger receptors (SR-As) are a family of surface-expressed receptors who bind a wide range of polyanionic ligands including bacterial components and nucleic acids and play a role in innate immunity. Macrophage receptor with collagenous structure (MARCO) is a SR-A family member that has been studied in mammals largely for its role in binding bacteria. To date there is little information about SR-As in general and MARCO specifically in fish, particularly what ligands individual SR-A family members bind remains largely unknown. In the present study two novel rainbow trout MARCO transcript variants have been identified and their sequence and putative protein domains have been analyzed. When overexpressed in CHSE-214, a cell line that appears to lack functional scavenger receptors, GFP-tagged rtMARCO-1 and rtMARCO-2 were able to bind gram-positive, and gram-negative bacteria of both mammalian and aquatic sources. rtMARCO appears to bind bacteria via its scavenger receptor cysteine-rich (SRCR) domain, because SRCR deleted rtMARCO-1 and -2 were unable to bind bacteria. rtMARCO did not show any binding to the yeast cell wall component zymosan or to double-stranded (ds)RNA. This is the first time rainbow trout MARCO sequences have been identified and the first in-depth study exploring their ligand binding profile. This study provides novel insight into the role of rainbow trout MARCO in bacterial innate immunity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. How bacterial cell division might cheat turgor pressure - a unified mechanism of septal division in Gram-positive and Gram-negative bacteria.

    Science.gov (United States)

    Erickson, Harold P

    2017-08-01

    An important question for bacterial cell division is how the invaginating septum can overcome the turgor force generated by the high osmolarity of the cytoplasm. I suggest that it may not need to. Several studies in Gram-negative bacteria have shown that the periplasm is isoosmolar with the cytoplasm. Indirect evidence suggests that this is also true for Gram-positive bacteria. In this case the invagination of the septum takes place within the uniformly high osmotic pressure environment, and does not have to fight turgor pressure. A related question is how the V-shaped constriction of Gram-negative bacteria relates to the plate-like septum of Gram-positive bacteria. I collected evidence that Gram-negative bacteria have a latent capability of forming plate-like septa, and present a model in which septal division is the basic mechanism in both Gram-positive and Gram-negative bacteria. © 2017 WILEY Periodicals, Inc.

  2. Automated annotation of mobile antibiotic resistance in Gram-negative bacteria: the Multiple Antibiotic Resistance Annotator (MARA) and database.

    Science.gov (United States)

    Partridge, Sally R; Tsafnat, Guy

    2018-04-01

    Multiresistance in Gram-negative bacteria is often due to acquisition of several different antibiotic resistance genes, each associated with a different mobile genetic element, that tend to cluster together in complex conglomerations. Accurate, consistent annotation of resistance genes, the boundaries and fragments of mobile elements, and signatures of insertion, such as DR, facilitates comparative analysis of complex multiresistance regions and plasmids to better understand their evolution and how resistance genes spread. To extend the Repository of Antibiotic resistance Cassettes (RAC) web site, which includes a database of 'features', and the Attacca automatic DNA annotation system, to encompass additional resistance genes and all types of associated mobile elements. Antibiotic resistance genes and mobile elements were added to RAC, from existing registries where possible. Attacca grammars were extended to accommodate the expanded database, to allow overlapping features to be annotated and to identify and annotate features such as composite transposons and DR. The Multiple Antibiotic Resistance Annotator (MARA) database includes antibiotic resistance genes and selected mobile elements from Gram-negative bacteria, distinguishing important variants. Sequences can be submitted to the MARA web site for annotation. A list of positions and orientations of annotated features, indicating those that are truncated, DR and potential composite transposons is provided for each sequence, as well as a diagram showing annotated features approximately to scale. The MARA web site (http://mara.spokade.com) provides a comprehensive database for mobile antibiotic resistance in Gram-negative bacteria and accurately annotates resistance genes and associated mobile elements in submitted sequences to facilitate comparative analysis.

  3. Dynamics of mono- and dual-species biofilm formation and interactions between Staphylococcus aureus and Gram-negative bacteria.

    Science.gov (United States)

    Makovcova, Jitka; Babak, Vladimir; Kulich, Pavel; Masek, Josef; Slany, Michal; Cincarova, Lenka

    2017-07-01

    Microorganisms are not commonly found in the planktonic state but predominantly form dual- and multispecies biofilms in almost all natural environments. Bacteria in multispecies biofilms cooperate, compete or have neutral interactions according to the involved species. Here, the development of mono- and dual-species biofilms formed by Staphylococcus aureus and other foodborne pathogens such as Salmonella enterica subsp. enterica serovar Enteritidis, potentially pathogenic Raoultella planticola and non-pathogenic Escherichia coli over the course of 24, 48 and 72 h was studied. Biofilm formation was evaluated by the crystal violet assay (CV), enumeration of colony-forming units (CFU cm -2 ) and visualization using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). In general, Gram-negative bacterial species and S. aureus interacted in a competitive manner. The tested Gram-negative bacteria grew better in mixed dual-species biofilms than in their mono-species biofilms as determined using the CV assay, CFU ml -2 enumeration, and CLSM and SEM visualization. In contrast, the growth of S. aureus biofilms was reduced when cultured in dual-species biofilms. CLSM images revealed grape-like clusters of S. aureus and monolayers of Gram-negative bacteria in both mono- and dual-species biofilms. S. aureus clusters in dual-species biofilms were significantly smaller than clusters in S. aureus mono-species biofilms. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  4. Mechanics of membrane bulging during cell-wall disruption in Gram-negative bacteria

    Science.gov (United States)

    Daly, Kristopher E.; Huang, Kerwyn Casey; Wingreen, Ned S.; Mukhopadhyay, Ranjan

    2011-04-01

    The bacterial cell wall is a network of sugar strands crosslinked by peptides that serve as the primary structure for bearing osmotic stress. Despite its importance in cellular survival, the robustness of the cell wall to network defects has been relatively unexplored. Treatment of the Gram-negative bacterium Escherichia coli with the antibiotic vancomycin, which disrupts the crosslinking of new material during growth, leads to the development of pronounced bulges and eventually of cell lysis. Here, we model the mechanics of the bulging of the cytoplasmic membrane through pores in the cell wall. We find that the membrane undergoes a transition between a nearly flat state and a spherical bulge at a critical pore radius of ~20 nm. This critical pore size is large compared to the typical distance between neighboring peptides and glycan strands, and hence pore size acts as a constraint on network integrity. We also discuss the general implications of our model to membrane deformations in eukaryotic blebbing and vesiculation in red blood cells.

  5. Expression levels of matrix metalloproteinase-9 and gram-negative bacteria in symptomatic and asymptomatic periapical lesions.

    Science.gov (United States)

    Ahmed, Geraldine M; El-Baz, Alaa A; Hashem, Ahmed Abdel Rahman; Shalaan, Abeer K

    2013-04-01

    The aim of this study was to test the hypothesis that the expression of matrix metalloproteinase (MMP)-9 is significantly elevated in patients with symptomatic apical periodontitis and to correlate this with the detected amount of gram-negative bacteria. Twenty-six patients with periapical lesions involving at least 2 teeth were included in this study. The patients were divided into 2 groups: the symptomatic (SYM) group included 13 patients expressing pain with periapical lesions, and the asymptomatic (ASYM) group included 13 patients expressing no pain. Root canal treatment was performed followed by endodontic surgery and periapical lesion collection. Periapical lesions were serially cut into 4-μ sections. Some sections were processed for histologic examination using hematoxylin-eosin stain. Other sections were processed for immunohistochemical examination. For MMP-9, the area fraction of the positive cells was measured, and the percentage of the MMP-9-immunopositive area to the total area of the microscopic field was calculated. For gram-negative stain cells, the number of cells showing the pink-red color was counted per microscopic field. The Student's t test was used to compare the SYM and ASYM groups. The Pearson correlation coefficient was used to determine a significant correlation between the number of cells and the MMP-9 level. The significance level was set at P ≤ .05. The SYM group showed a statistically significantly higher mean number of gram-negative cells (P = .001) and MMP-9 area percent (P negative cells and the MMP-9 area percent (Pnegative bacteria and MMP-9 in symptomatic periapical lesions. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  6. Screening of antibiotic susceptibility to β-lactam-induced elongation of Gram-negative bacteria based on dielectrophoresis.

    Science.gov (United States)

    Chung, Cheng-Che; Cheng, I-Fang; Chen, Hung-Mo; Kan, Heng-Chuan; Yang, Wen-Horng; Chang, Hsien-Chang

    2012-04-03

    We demonstrate a rapid antibiotic susceptibility test (AST) based on the changes in dielectrophoretic (DEP) behaviors related to the β-lactam-induced elongation of Gram-negative bacteria (GNB) on a quadruple electrode array (QEA). The minimum inhibitory concentration (MIC) can be determined within 2 h by observing the changes in the positive-DEP frequency (pdf) and cell length of GNB under the cefazolin (CEZ) treatment. Escherichia coli and Klebsiella pneumoniae and the CEZ are used as the sample bacteria and antibiotic respectively. The bacteria became filamentous due to the inhibition of cell wall synthesis and cell division and cell lysis occurred for the higher antibiotic dose. According to the results, the pdfs of wild type bacteria decrease to hundreds of kHz and the cell length is more than 10 μm when the bacterial growth is inhibited by the CEZ treatment. In addition, the growth of wild type bacteria and drug resistant bacteria differ significantly. There is an obvious decrease in the number of wild type bacteria but not in the number of drug resistant bacteria. Thus, the drug resistance of GNB to β-lactam antibiotics can be rapidly assessed. Furthermore, the MIC determined using dielectrophoresis-based AST (d-AST) was consistent with the results of the broth dilution method. Utilizing this approach could reduce the time needed for bacteria growth from days to hours, help physicians to administer appropriate antibiotic dosages, and reduce the possibility of the occurrence of multidrug resistant (MDR) bacteria.

  7. Glycosaminoglycans are involved in pathogen adherence to corneal epithelial cells differently for Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Beatriz García

    2016-11-01

    Full Text Available The epithelium of the cornea is continuously exposed to pathogens, and adhesion to epithelial cells is regarded as an essential first step in bacterial pathogenesis. In this article, the involvement of glycosaminoglycans in the adhesion of various pathogenic bacteria to corneal epithelial cells is analyzed. All microorganisms use glycosaminoglycans as receptors, but arranged in different patterns depending on the Gram-type of the bacterium. The heparan sulfate chains of syndecans are the main receptors, though other molecular species also seem to be involved, particularly in Gram-negative bacteria. Adherence is inhibited differentially by peptides, including heparin binding sequences, indicating the participation of various groups of Gram-positive and -negative adhesins. The length of the saccharides produces a major effect, and low molecular weight chains inhibit the binding of Gram-negative microorganisms but increase the adherence of Gram-positives. Pathogen adhesion appears to occur preferentially through sulfated domains, and is very dependent on N- and 6-O-sulfation of the glucosamine residue and, to a lesser extent, 2-O sulfation of uronic acid. These data show the differential use of corneal receptors, which could facilitate the development of new anti-infective strategies.

  8. Antibacterial Activity of Stenotrophomonas maltophilia Endolysin P28 against both Gram-positive and Gram-negative Bacteria.

    Science.gov (United States)

    Dong, Hongling; Zhu, Chaoyang; Chen, Jingyi; Ye, Xing; Huang, Yu-Ping

    2015-01-01

    Maltocin P28 is a phage-tail like bacteriocin produced by Stenotrophomonas maltophilia P28. The ORF8 of maltocin P28 gene cluster is predicted to encode an endolysin and we name it endolysin P28. Sequence analysis revealed that it contains the lysozyme_like superfamily conserved domain. Endolysin P28 has the four consensus motifs as that of Escherichia coli phage lambda gpR. In this study, endolysin P28 was expressed in E. coli BL21 (DE3) and purified with a C-terminal oligo-histidine tag. The antibacterial activity of endolysin P28 increased as the temperature rose from 25 to 45°C. Thermostability assays showed that endolysin P28 was stable up to 50°C, while its residual activity was reduced by 55% after treatment at 70°C for 30 min. Acidity and high salinity could enhance its antibacterial activity. Endolysin P28 exhibited a broad antibacterial activity against 14 out of 16 tested Gram-positive and Gram-negative bacteria besides S. maltophilia. Moreover, it could effectively lyse intact Gram-negative bacteria in the absence of ethylenediaminetetraacetic acid as an outer membrane permeabilizer. Therefore, the characteristics of endolysin P28 make it a potential therapeutic agent against multi-drug-resistant pathogens.

  9. Antibacterial activity of Stenotrophomonas maltophilia endolysin P28 against both Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Hongling eDong

    2015-11-01

    Full Text Available Maltocin P28 is a phage-tail like bacteriocin produced by Stenotrophomonas maltophilia P28. The ORF8 of maltocin P28 gene cluster is predicted to encode an endolysin and we name it endolysin P28. Sequence analysis revealed that it contains the lysozyme_like superfamily conserved domain. Endolysin P28 has the four consensus motifs as that of Escherichia coli phage lambda gpR. In this study endolysin P28 was expressed in E. coli BL21 (DE3 and purified with a C-terminal oligo-histidine tag. The antibacterial activity of endolysin P28 increased as the temperature rose from 25°C to 45°C. Thermostability assays showed that endolysin P28 was stable up to 50°C, while its residual activity was reduced by 55% after treatment at 70°C for 30 min. Acidity and high salinity could enhance its antibacterial activity. Endolysin P28 exhibited a broad antibacterial activity against 14 out of 16 tested Gram-positive and Gram-negative bacteria besides S. maltophilia. Moreover, it could effectively lyse intact Gram-negative bacteria in the absence of ethylenediaminetetraacetic acid (EDTA as an outer membrane permeabilizer. Therefore, the characteristics of endolysin P28 make it a potential therapeutic agent against multi-drug-resistant pathogens.

  10. EFFECT OF AEROSOLIZATION ON CULTURABILITY AND VIABILITY OF GRAM-NEGATIVE BACTERIA

    Science.gov (United States)

    Estimations of the bacterial content of air can be more easily made now than a decade ago, with colony formation the method of choice for enumeration of airborne bacteria.However, plate counts are subject to error because bacteria exposed to the air may remain viable yet lose the...

  11. Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study

    Directory of Open Access Journals (Sweden)

    Azam A

    2012-12-01

    Full Text Available Ameer Azam,1,2 Arham S Ahmed,2 Mohammad Oves,3 Mohammad S Khan,3 Sami S Habib,1 Adnan Memic11Centre of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia; 2Centre of Excellence in Materials Science (Nanomaterials, 3Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh, IndiaBackground: Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria.Methods and results: Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3 were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa and Gram-positive (Staphylococcus aureus and Bacillus subtilis bacteria.Conclusion: Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3

  12. Fluctuations in the population density of Gram-negative bacteria in a chernozem in the course of a succession initiated by moistening and chitin and cellulose introduction

    Science.gov (United States)

    Polyanskaya, L. M.; Ivanov, K. E.; Zvyagintsev, D. G.

    2012-10-01

    The role has been studied of Gram-negative bacteria in the destruction of polymers widely spread in soils: chitin and cellulose. The introduction of chitin had no positive effect on the population density of Gram-negative bacteria, but it advanced the date of their appearance: the maximum population density of Gram-negative bacteria was recorded not on the 7th-15th day as in the control but much earlier, on the 3rd-7th day of the experiment. Consequently, the introduction of chitin as an additional source of nutrition promoted revealing of the Gram-negative bacteria already at the early stages of the succession. In the course of the succession, when the fungal mycelium begins to die off, the actinomycetic mycelium increases in length, i.e., Gram-negative bacteria are replaced at this stage with Gram-positive ones, the leading role among which belongs to actinomycetes. The growth rate of Gram-negative bacteria is higher than that of actinomycetes, so they start chitin utilization at the early stages of the succession, whereas actinomycetes dominate at the late stages. The population density of Gram-negative bacteria was lower under the anaerobic conditions as compared with that in the aerobic ones. The population density of Gram-negative bacteria in the lower layer of the A horizon and in the B horizon was slightly higher only in the case of the chitin introduction. When cellulose was introduced into the soil under aerobic conditions, the population density of Gram-negative bacteria in all the layers of the A horizon was maximal from the 14th to the 22nd day of the experiment. Cellulose was utilized in the soil mostly by fungi, and this was suggested by the increase of the length of the fungal mycelium. Simultaneously, an increase in the length of the actinomycetal mycelium was observed, as these organisms also perform cellulose hydrolysis in soils. The Gram-negative bacteria began to develop at the stage of the fungal mycelium destruction, which indirectly

  13. Quorum sensing signal molecules (acylated homoserine lactones) in Gram-negative fish pathogenic bacteria

    DEFF Research Database (Denmark)

    Bruhn, Jesper Bartholin; Dalsgaard, Inger; Nielsen, K.F.

    2005-01-01

    and plant-pathogenic bacteria. A total of 59 strains, representing 9 different fish pathogenic species, were tested against 2 AHL monitor bacteria (Agrobacterium tumefaciens NT1 [pZLR4] and Chromobacterium violaceum CV026) in a well diffusion assay and by thin-layer chromatography (TLC). Representative...... samples were further characterized by high performance liquid chromatography-high resolution mass spectrometry (HPLC-HR-MS). AHLs were produced by all strains of Aeromonas salmonicida, Aeromonas hydrophila, Yersinia ruckeri, Vibrio salmonicida, and Vibrio vulnificus. Some strains of atypical Aeromonas...

  14. Loss of outer membrane integrity in gram negative bacteria by silver ...

    Indian Academy of Sciences (India)

    9

    due to rise of Multiple Drug Resistant (MDR) strains2-4. The importance and increasing incidence of infections .... (1998)19. In the presence of viable bacteria, TTC is reduced to red formazan and thus the change from colorless to red color indicates the viability of the bacterial cells. All bacterial strains were grown in 10 ml.

  15. Genome mining reveals unlocked bioactive potential of marine Gram-negative bacteria

    DEFF Research Database (Denmark)

    Machado, Henrique; Sonnenschein, Eva; Melchiorsen, Jette

    2015-01-01

    - and Gammaproteobacteria collected during the Galathea 3 expedition were sequenced and mined for natural product encoding gene clusters. Results: Independently of genome size, bacteria of all tested genera carried a large number of clusters encoding different potential bioactivities, especially within the Vibrionaceae...... that will facilitate natural product discovery in the future....

  16. Classification of gram-positive and gram-negative foodborne pathogenic bacteria with hyperspectral microscope imaging

    Science.gov (United States)

    Optical method with hyperspectral microscope imaging (HMI) has potential for identification of foodborne pathogenic bacteria from microcolonies rapidly with a cell level. A HMI system that provides both spatial and spectral information could be an effective tool for analyzing spectral characteristic...

  17. Hyperspectral microscope imaging methods to classify gram-positive and gram-negative foodborne pathogenic bacteria

    Science.gov (United States)

    An acousto-optic tunable filter-based hyperspectral microscope imaging method has potential for identification of foodborne pathogenic bacteria from microcolony rapidly with a single cell level. We have successfully developed the method to acquire quality hyperspectral microscopic images from variou...

  18. Metallo- β-lactamases among Multidrug Resistant (MDR Gram Negative Bacteria Isolated from Clinical Specimens during 2009 in Sanandaj, Kurdistan Province

    Directory of Open Access Journals (Sweden)

    Himen Salimizand

    2012-08-01

    Full Text Available Background: Today, there are numerous reports about emerging multi drug resistant gram negative bacteria all around the world, especially in ICUs. Rarely, Metallo-β-lactamase (MBL enzymes are responsible for these cases. Study of MBLs for diagnosing and preventing distribution of the origin of infection are critical issues. In addition, we would like to compare the efficacy of Iranian and foreign- made antibiotic disks. Materials and Methods: During 2009 all entered clinical specimens to the laboratory tested for detecting gram negative bacteria. Isolated bacteria were tested by Kirby-Bauer method to antibiotic susceptibility test by Iranian and foreign (MAST disks. For gram negative carbapenem resistant isolates, PCR technique used to detect VIM, GIM, and SIM variants of MBLs.Results: During one year, 17890 clinical specimens referred Besat laboratory. The most specimen was Urine (8172 followed by blood culture (5190 that in which 1110 gram negative and positives isolated. Out of which, 778 (70% of isolates were gram negatives. MDR gram negatives were 157 (20.2%. Imipenem and meropenem were the most efficient antibiotics (all susceptible and ceftriaxone was the least (19 % susceptible. E. coli was the most prevalent isolate. 79 Gram negative isolates (10.1% were resistant to Iranian-made discs but all susceptible for foreign ones. All 79 isolates were tested by PCR for MBL genes, that, all were negative. Besides, Iranian imipenem and cefepime disks have had distinguishable difference in susceptibility of isolates.Conclusion: Fortunately, none of gram negative isolates were MBL producer, which revealed no colonization of MBL producing bacteria. Iranian-made disks appear efficient except for imipenem and cefepime.

  19. Amplifiable DNA from Gram-negative and Gram-positive bacteria by a low strength pulsed electric field method

    Science.gov (United States)

    Vitzthum, Frank; Geiger, Georg; Bisswanger, Hans; Elkine, Bentsian; Brunner, Herwig; Bernhagen, Jürgen

    2000-01-01

    An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of Pulses had an exponential decay waveform with a time constant of 3.4 µs. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and electrophoresis were minimal. The lysates contained non-fragmented DNA which was readily amplifiable by PCR. As the method was not limited to samples of high specific resistance, it should be applicable to physiological fluids and be useful for genomic and DNA diagnostic applications. PMID:10734214

  20. European and Russian physician awareness of best management approaches for infections due to antibiotic-resistant Gram-negative bacteria.

    Science.gov (United States)

    Irani, Paurus; Salimi, Tehseen; Epstein, Robert; Leone-Perkins, Megan; Aubert, Ronald; Khalid, Mona; Epstein, Emma; Teagarden, J Russell

    2017-08-01

    The rapid spread of infections due to antibiotic-resistant, Gram-negative bacteria in Europe and surrounding regions requires a heightened level of awareness among physicians within their practice settings. We surveyed 800 physicians who treat these infections across France, Germany, Spain, Italy, and Russia to assess their awareness of best management approaches. We found that more than two-thirds do not consider themselves highly aware of best management practices. The respondents are facing these resistant infections as evidenced by the antibiotics they report using and their stated interest in newer agents. Respondents indicated that precious time is lost waiting for culture results, but also said they will need more information about accuracy, use, and costs for adopting rapid molecular testing. The survey further identified the need for treatment guidelines and clinical decision support tools that can be applied at the bedside.

  1. Inhibition of various gram-positive and gram-negative bacteria growth on selenium nanoparticle coated paper towels.

    Science.gov (United States)

    Wang, Qi; Larese-Casanova, Philip; Webster, Thomas J

    2015-01-01

    There are wide spread bacterial contamination issues on various paper products, such as paper towels hanging in sink splash zones or those used to clean surfaces, filter papers used in water and air purifying systems, and wrappings used in the food industry; such contamination may lead to the potential spread of bacteria and consequent severe health concerns. In this study, selenium nanoparticles were coated on normal paper towel surfaces through a quick precipitation method, introducing antibacterial properties to the paper towels in a healthy way. Their effectiveness at preventing biofilm formation was tested in bacterial assays involving Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus epidermidis. The results showed significant and continuous bacteria inhibition with about a 90% reduction from 24 to 72 hours for gram-positive bacteria including S. aureus and S. epidermidis. The selenium coated paper towels also showed significant inhibition of gram-negative bacteria like P. aeruginosa and E. coli growth at about 57% and 84%, respectively, after 72 hours of treatment. Therefore, this study established a promising selenium-based antibacterial strategy to prevent bacterial growth on paper products, which may lead to the avoidance of bacteria spreading and consequent severe health concerns.

  2. Susceptibility of Colistin-Resistant, Gram-Negative Bacteria to Antimicrobial Peptides and Ceragenins.

    Science.gov (United States)

    Hashemi, Marjan M; Rovig, John; Weber, Scott; Hilton, Brian; Forouzan, Mehdi M; Savage, Paul B

    2017-08-01

    The susceptibility of colistin-resistant clinical isolates of Klebsiella pneumoniae to ceragenins and antimicrobial peptides (AMPs) suggests that there is little to no cross-resistance between colistin and ceragenins/AMPs and that lipid A modifications are found in bacteria with modest changes in susceptibility to ceragenins and with high levels of resistance to colistin. These results suggest that there are differences in the resistance mechanisms to colistin and ceragenins/AMPs. Copyright © 2017 Hashemi et al.

  3. Nanotransformation of vancomycin overcomes the intrinsic resistance of Gram-negative bacteria

    OpenAIRE

    Ivanova, Kristina Dimitrova; Hoyo Pérez, Javier; Francesko, Antonio; Tzanov, Tzanko

    2017-01-01

    The increased emergence of antibiotic-resistant bacteria is a growing public health concern, and although new drugs are constantly being sought, the pace of development is slow compared with the evolution and spread of multidrug- resistant species. In this study, we developed a novel broad-spectrum antimicrobial agent by simply transforming vancomycin into nanoform using sonochemistry. Vancomycin is a glycopeptide antibiotic largely used for the treatment of infections caused by Gram-positive...

  4. Activity of siderophores against drug-resistant Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Gokarn K

    2018-01-01

    Full Text Available Karuna Gokarn,1,2 Ramprasad B Pal1 1Department of Microbiology, Sir Hurkisondas Nurrotumdas Medical Research Society, 2Caius Research Laboratory, St Xavier’s College, Mumbai, India Abstract: Infections by drug-resistant bacteria are life-threatening. As iron is a vital element for the growth of bacteria, iron-chelating agents (siderophores can be used to arrest their multiplication. Exogenous siderophores – exochelin-MS and deferoxamine-B – were evaluated for their inhibitory activity against methicillin-resistant Staphylococcus aureus and metallo-β-lactamase producers – Pseudomonas aeruginosa and Acinetobacter baumannii – by disc diffusion, micro-broth dilution, and turbidimetric growth assays. The drug-resistant isolates were inhibited by the synergistic activity of siderophores and antibiotics. Minimum inhibitory concentration of exochelin-MS+ampicillin for different isolates was between 0.05 and 0.5 mg/mL. Minimum inhibitory concentration of deferoxamine-B+ampicillin was 1.0 mg/mL and greater. Iron-chelation therapy could provide a complementary approach to overcome drug resistance in pathogenic bacteria. Keywords: iron-chelation, xenosiderophores, exochelin MS, deferoxamine B

  5. Antibacterial activity of sphingoid bases and fatty acids against Gram-positive and Gram-negative bacteria.

    Science.gov (United States)

    Fischer, Carol L; Drake, David R; Dawson, Deborah V; Blanchette, Derek R; Brogden, Kim A; Wertz, Philip W

    2012-03-01

    There is growing evidence that the role of lipids in innate immunity is more important than previously realized. How lipids interact with bacteria to achieve a level of protection, however, is still poorly understood. To begin to address the mechanisms of antibacterial activity, we determined MICs and minimum bactericidal concentrations (MBCs) of lipids common to the skin and oral cavity--the sphingoid bases D-sphingosine, phytosphingosine, and dihydrosphingosine and the fatty acids sapienic acid and lauric acid--against four Gram-negative bacteria and seven Gram-positive bacteria. Exact Kruskal-Wallis tests of these values showed differences among lipid treatments (P 500 μg/ml). Sapienic acid (MBC range, 31.3 to 375.0 μg/ml) was active against Streptococcus sanguinis, Streptococcus mitis, and Fusobacterium nucleatum but not active against Escherichia coli, Staphylococcus aureus, S. marcescens, P. aeruginosa, Corynebacterium bovis, Corynebacterium striatum, and Corynebacterium jeikeium (MBC > 500 μg/ml). Lauric acid (MBC range, 6.8 to 375.0 μg/ml) was active against all bacteria except E. coli, S. marcescens, and P. aeruginosa (MBC > 500 μg/ml). Complete killing was achieved as early as 0.5 h for some lipids but took as long as 24 h for others. Hence, sphingoid bases and fatty acids have different antibacterial activities and may have potential for prophylactic or therapeutic intervention in infection.

  6. Chemical resistance of the gram-negative bacteria to different sanitizers in a water purification system

    Directory of Open Access Journals (Sweden)

    Penna Thereza CV

    2006-08-01

    Full Text Available Abstract Background Purified water for pharmaceutical purposes must be free of microbial contamination and pyrogens. Even with the additional sanitary and disinfecting treatments applied to the system (sequential operational stages, Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas alcaligenes, Pseudomonas picketti, Flavobacterium aureum, Acinetobacter lowffi and Pseudomonas diminuta were isolated and identified from a thirteen-stage purification system. To evaluate the efficacy of the chemical agents used in the disinfecting process along with those used to adjust chemical characteristics of the system, over the identified bacteria, the kinetic parameter of killing time (D-value necessary to inactivate 90% of the initial bioburden (decimal reduction time was experimentally determined. Methods Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas alcaligenes, Pseudomonas picketti, Flavobacterium aureum, Acinetobacter lowffi and Pseudomonas diminuta were called in house (wild bacteria. Pseudomonas diminuta ATCC 11568, Pseudomonas alcaligenes INCQS , Pseudomonas aeruginosa ATCC 15442, Pseudomonas fluorescens ATCC 3178, Pseudomonas picketti ATCC 5031, Bacillus subtilis ATCC 937 and Escherichia coli ATCC 25922 were used as 'standard' bacteria to evaluate resistance at 25°C against either 0.5% citric acid, 0.5% hydrochloric acid, 70% ethanol, 0.5% sodium bisulfite, 0.4% sodium hydroxide, 0.5% sodium hypochlorite, or a mixture of 2.2% hydrogen peroxide (H2O2 and 0.45% peracetic acid. Results The efficacy of the sanitizers varied with concentration and contact time to reduce decimal logarithmic (log10 population (n cycles. To kill 90% of the initial population (or one log10 cycle, the necessary time (D-value was for P. aeruginosa into: (i 0.5% citric acid, D = 3.8 min; (ii 0.5% hydrochloric acid, D = 6.9 min; (iii 70% ethanol, D = 9.7 min; (iv 0.5% sodium bisulfite, D = 5.3 min; (v 0.4% sodium hydroxide, D = 14.2 min; (vi 0.5% sodium

  7. Prevalence and risk factors for CTX-M gram-negative bacteria in hospitalized patients at a tertiary care hospital in Kilimanjaro, Tanzania

    DEFF Research Database (Denmark)

    Sonda, Tolbert; Kumburu, Happiness; van Zwetselaar, Marco

    2018-01-01

    Emergence and spread of extended spectrum beta-lactamase (ESBL)-producing gram-negative bacteria, mainly due to CTX-M, is a major global public health problem. Patients infected with ESBL-producing gram-negative bacteria have an increased risk of treatment failure and death. We investigated...... 2015 were fully genome sequenced. The prevalence of ESBL-producing gram-negative bacteria was determined based on the presence of blaCTX-M. The odds ratio (OR) and risk factors for ESBL-producing gram-negative bacteria due to CTX-M were assessed using logistic regression models. The overall CTX.......14 (0.04–0.46), p = 0.001; and the OR for patients with wound infections was 0.24 (0.09–0.61), p = 0.003. The prevalence of ESBL-producing gram-negative bacteria due to CTX-M in this setting is relatively low compared to other previous reports in similar settings. However, to properly stop further...

  8. An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria

    Science.gov (United States)

    Cox, Georgina; Koteva, Kalinka; Wright, Gerard D.

    2014-01-01

    Objectives An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. Methods E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. Results The anthracycline Antibiotic 301A1 was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure–activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A1 abolishes activity. Conclusions Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. PMID:24627312

  9. Cigarette smoke inhibits macrophage sensing of Gram-negative bacteria and lipopolysaccharide: relative roles of nicotine and oxidant stress.

    Science.gov (United States)

    McMaster, S K; Paul-Clark, M J; Walters, M; Fleet, M; Anandarajah, J; Sriskandan, S; Mitchell, J A

    2008-02-01

    Smoking cigarettes is a major risk factor for the development of cardiovascular and respiratory disease. Moreover, smokers are more prone to infections. This has been associated with a suppression of the immune system by smoke. However, it is not clear how cigarette smoke affects the ability of immune cells to sense pathogens. Cigarette smoke contains a large number of molecules which may mediate responses on immune cells and of these, nicotine and oxidants have both been identified as inhibitory for the sensing of bacterial lipopolysaccharide (LPS). Nitric oxide synthase (NOS) and tumour necrosis factor (TNF)-alpha are both induced in macrophages on stimulation with Gram negative bacteria or LPS. We used murine macrophages stimulated with whole heat-killed bacteria or LPS. We measured output of NO (as nitrite) and TNFalpha, NOS protein by Western blotting and cellular oxidant stress. Cigarette smoke extract suppressed the ability of murine macrophages to release NO, but not TNFalpha in response to whole bacteria. Cigarette smoke extract also inhibited nitric oxide synthase II protein expression in response to LPS. The effects of cigarette smoke extract on nitrite formation stimulated by LPS were unaffected by inhibition of nicotinic receptors with alpha-bungarotoxin (100 units ml(-1)). However, the effects of cigarette smoke extract on LPS-induced nitrite formation were mimicked by hydrogen peroxide and reversed by the anti-oxidants N-acetyl cysteine and glutathione. We suggest that cigarette smoke exerts its immunosuppressive effects through an oxidant-dependent and not a nicotine-dependent mechanism.

  10. Nanoparticle targeting of Gram-positive and Gram-negative bacteria for magnetic-based separations of bacterial pathogens

    Science.gov (United States)

    Lu, Hoang D.; Yang, Shirley S.; Wilson, Brian K.; McManus, Simon A.; Chen, Christopher V. H.-H.; Prud'homme, Robert K.

    2017-04-01

    Antimicrobial resistance is a healthcare problem of increasing significance, and there is increasing interest in developing new tools to address bacterial infections. Bacteria-targeting nanoparticles hold promise to improve drug efficacy, compliance, and safety. In addition, nanoparticles can also be used for novel applications, such as bacterial imaging or bioseperations. We here present the use of a scalable block-copolymer-directed self-assembly process, Flash NanoPrecipitation, to form zinc(II)-bis(dipicolylamine) modified nanoparticles that bind to both Gram-positive and Gram-negative bacteria with specificity. Particles have tunable surface ligand densities that change particle avidity and binding efficacy. A variety of materials can be encapsulated into the core of the particles, such as optical dyes or iron oxide colloids, to produce imageable and magnetically active bacterial targeting constructs. As a proof-of-concept, these particles are used to bind and separate bacteria from solution in a magnetic column. Magnetic manipulation and separation would translate to a platform for pathogen identification or removal. These magnetic and targeted nanoparticles enable new methods to address bacterial infections.

  11. Identification of a novel storage glycine-rich peptide from guava (Psidium guajava) seeds with activity against Gram-negative bacteria.

    Science.gov (United States)

    Pelegrini, Patricia B; Murad, André M; Silva, Luciano P; Dos Santos, Rachel C P; Costa, Fabio T; Tagliari, Paula D; Bloch, Carlos; Noronha, Eliane F; Miller, Robert N G; Franco, Octavio L

    2008-08-01

    Bacterial pathogens cause an expressive negative impact worldwide on human health, with ever increasing treatment costs. A significant rise in resistance to commercial antibiotics has been observed in pathogenic bacteria responsible for urinary and gastro-intestinal infections. Towards the development of novel approaches to control such common infections, a number of defense peptides with antibacterial activities have been characterized. In this report, the peptide Pg-AMP1 was isolated from guava seeds (Psidium guajava) and purified using a Red-Sepharose Cl-6B affinity column followed by a reversed-phase HPLC (Vydac C18-TP). Pg-AMP1 showed no inhibitory activity against fungi, but resulted in a clear growth reduction in Klebsiella sp. and Proteus sp., which are the principal pathogens involved in urinary and gastro-intestinal hospital infections. SDS-PAGE and mass spectrometry (MALDI-ToF) characterized Pg-AMP1 a monomer with a molecular mass of 6029.34Da and small quantities of a homodimer. Amino acid sequencing revealed clear identity to the plant glycine-rich protein family, with Pg-AMP1 the first such protein with activity towards Gram-negative bacteria. Furthermore, Pg-AMP1 showed a 3D structural homology to an enterotoxin from Escherichia coli, and other antibacterial proteins, revealing that it might act by formation of a dimer. Pg-AMP1 shows potential, in a near future, to contribute to development of novel antibiotics from natural sources.

  12. Tn5/7-lux: a versatile tool for the identification and capture of promoters in gram-negative bacteria.

    Science.gov (United States)

    Bruckbauer, Steven T; Kvitko, Brian H; Karkhoff-Schweizer, RoxAnn R; Schweizer, Herbert P

    2015-02-04

    The combination of imaging technologies and luciferase-based bioluminescent bacterial reporter strains provide a sensitive and simple non-invasive detection method (photonic bioimaging) for the study of diverse biological processes, as well as efficacy of therapeutic interventions, in live animal models of disease. The engineering of bioluminescent bacteria required for photonic bioimaging is frequently hampered by lack of promoters suitable for strong, yet stable luciferase gene expression. We devised a novel method for identification of constitutive native promoters in Gram-negative bacteria. The method is based on a Tn5/7 transposon that exploits the unique features of Tn5 (random transposition) and Tn7 (site-specific transposition). The transposons are designed such that Tn5 transposition will allow insertion of a promoter-less bacterial luxCDABE operon downstream of a bacterial gene promoter. Cloning of DNA fragments from luminescent isolates results in a plasmid that replicates in pir (+) hosts. Sequencing of the lux-chromosomal DNA junctions on the plasmid reveals transposon insertion sites within genes or operons. The plasmid is also a mini-Tn7-lux delivery vector that can be used to introduce the promoter-lux operon fusion into other derivatives of the bacterium of interest in an isogenic fashion. Alternatively, promoter-containing sequences can be PCR-amplified from plasmid or chromosomal DNA and cloned into a series of accompanying mini-Tn7-lux vectors. The mini-Tn5/7-lux and mini-Tn7-lux vectors are equipped with diverse selection markers and thus applicable in numerous Gram-negative bacteria. Various mini-Tn5/7-lux vectors were successfully tested for transposition and promoter identification by imaging in Acinetobacter baumannii, Escherichia coli, and Burkholderia pseudomallei. Strong promoters were captured for lux expression in E. coli and A. baumannii. Some mini-Tn7-lux vectors are also equipped with attB sites for swapping of the lux operon with

  13. Bacillus pumilus of Palk Bay origin inhibits quorum-sensing-mediated virulence factors in Gram-negative bacteria.

    Science.gov (United States)

    Nithya, Chari; Aravindraja, Chairman; Pandian, Shunmugiah Karutha

    2010-05-01

    The aim of the current study was to inhibit quoring-sensing(QS)-mediated virulence factors of representative Gram-negative bacteria by marine bacterial isolates. Bacteria isolated from Palk Bay sediments were screened for anti-QS activity. Eleven strains inhibited QS signals in Chromobacterium violaceum (ATCC 12472) and C. violaceum CV026. The marine bacterial strain S8-07 reduced the accumulation of N-acyl homoserine lactone (AHLs) and showed significant inhibition of LasA protease(76%), LasB elastase(84%), caseinase(70%), pyocyanin (84%), pyoverdin and biofilm formation(87%) in Pseudomonas aeruginosa PAO1. Strain S8-07 also showed highly significant reduction (90%) in prodigiosin, secreted casienase (92%), hemolytic activity (73%) and biofilm formation (61%) in Serratia marcescens. Strain S8-07, identified as Bacillus pumilus (accession number FJ584416), showed distinct profiles of inhibition against the virulence factors of both P. aeruginosa PAO1 (las, rhl) and S. marcescens (shl). Polar extraction and proteinase K treatment of the culture supernatant confirmed that the anti-QS activity of S8-07 was indeed due to a protein molecule. Acidification assay and HPLC analysis revealed that the degradation of AHL was not due to lactonase activity, but rather, was due to acylase activity of S8-07. Thus, novel anti-QS acylase activity is reported for the first time from a B. pumilus strain of marine origin. (c) 2010 Elsevier Masson SAS. All rights reserved.

  14. Cerium oxide and iron oxide nanoparticles abolish the antibacterial activity of ciprofloxacin against gram positive and gram negative biofilm bacteria.

    Science.gov (United States)

    Masadeh, Majed M; Karasneh, Ghadah A; Al-Akhras, Mohammad A; Albiss, Borhan A; Aljarah, Khaled M; Al-Azzam, Sayer I; Alzoubi, Karem H

    2015-05-01

    Metal oxide nanoparticles have been suggested as good candidates for the development of antibacterial agents. Cerium oxide (CeO2) and iron oxide (Fe2O3) nanoparticles have been utilized in a number of biomedical applications. Here, the antibacterial activity of CeO2 and Fe2O3 nanoparticles were evaluated on a panel of gram positive and gram negative bacteria in both the planktonic and biofilm cultures. Additionally, the effect of combining CeO2 and Fe2O3 nanoparticles with the broad spectrum antibiotic ciprofloxacin on tested bacteria was investigated. Thus, minimum inhibitory concentrations (MICs) of CeO2 and Fe2O3 nanoparticles that are required to inhibit bacterial planktonic growth and bacterial biofilm, were evaluated, and were compared to the MICs of the broad spectrum antibiotic ciprofloxacin alone or in the presence of CeO2 and Fe2O3 nanoparticles. Results of this study show that both CeO2 and Fe2O3 nanoparticles fail to inhibit bacterial growth and biofilm biomass for all the bacterial strains tested. Moreover, adding CeO2 or Fe2O3 nanoparticles to the broad spectrum antibiotic ciprofloxacin almost abolished its antibacterial activity. Results of this study suggest that CeO2 and Fe2O3 nanoparticles are not good candidates as antibacterial agents, and they could interfere with the activity of important antibiotics.

  15. Carbapenem Resistance in Gram-Negative Bacteria: The Not-So-Little Problem in the Little Red Dot

    Directory of Open Access Journals (Sweden)

    Jocelyn Qi Min Teo

    2016-02-01

    Full Text Available Singapore is an international travel and medical hub and faces a genuine threat for import and dissemination of bacteria with broad-spectrum resistance. In this review, we described the current landscape and management of carbapenem resistance in Gram-negative bacteria (GNB in Singapore. Notably, the number of carbapenem-resistant Enterobacteriaceae has exponentially increased in the past two years. Resistance is largely mediated by a variety of mechanisms. Polymyxin resistance has also emerged. Interestingly, two Escherichia coli isolates with plasmid-mediated mcr-1 genes have been detected. Evidently, surveillance and infection control becomes critical in the local setting where resistance is commonly related to plasmid-mediated mechanisms, such as carbapenemases. Combination antibiotic therapy has been proposed as a last-resort strategy in the treatment of extensively drug-resistant (XDR GNB infections, and is widely adopted in Singapore. The diversity of carbapenemases encountered, however, presents complexities in both carbapenemase detection and the selection of optimal antibiotic combinations. One unique strategy introduced in Singapore is a prospective in vitro combination testing service, which aids physicians in the selection of individualized combinations. The outcome of this treatment strategy has been promising. Unlike countries with a predominant carbapenemase type, Singapore has to adopt management strategies which accounts for diversity in resistance mechanisms.

  16. Effect of pH and time on the accumulation of heavy metals in Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Yamina Benmalek

    2014-07-01

    Full Text Available The release of heavy metals into our environment is very important and causes an environmental pollution problem. Contamination of the aquatic environment by toxic heavy metals is a serious pollution problem because they can reach water-courses either naturally through a variety of geochemical processes or by direct discharge of municipal, agricultural and industrial wastewater. The bioremediation of heavy metals using microorganisms has received a great deal of attention in recent years because their potential application in industry. Microorganisms uptake metal either actively (bioaccumulation and passively (biosorption. Some bacteria have developed chromosomally or extra-chromosomally controlled detoxification mechanisms to overcome the detrimental effects of heavy metals. In the present work, we have studied resistance to heavy metals and the capacity of a Gram-negative bacteria to accumulate lead and zinc. Results obtained indicated that the bacterial strain exhibited high Minimal Inhibitory Concentration (MIC values for metal ions tested ranging from 75 mg/l to 500 mg/l and it was able to accumulate more than 90% of lead and zinc during the active growth cycle. Effect of pH and time on heavy metal removal was also studied properly.

  17. Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria

    Science.gov (United States)

    Gurunathan, Sangiliyandi; Han, Jae Woong; Kwon, Deug-Nam; Kim, Jin-Hoi

    2014-07-01

    Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results

  18. Antibacterial activity and interactions of plant essential oil combinations against Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Cristina Anamaria Semeniuc

    2017-04-01

    Full Text Available The aim of this study was to compare the antibacterial effects of several essential oils (EOs alone and in combination against different Gram-positive and Gram-negative bacteria associated with food products. Parsley, lovage, basil, and thyme EOs, as well as their mixtures (1:1, v/v, were tested against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhimurium. The inhibitory effects ranged from strong (thyme EO against E. coli to no inhibition (parsley EO against P. aeruginosa. Thyme EO exhibited strong (against E. coli, moderate (against S. typhimurium and B. cereus, or mild inhibitory effects (against P. aeruginosa and S. aureus, and basil EO showed mild (against E. coli and B. cereus or no inhibitory effects (against S. typhimurium, P. aeruginosa, and S. aureus. Parsley and lovage EOs revealed no inhibitory effects against all tested strains. Combinations of lovage/thyme and basil/thyme EOs displayed antagonistic effects against all bacteria, parsley/thyme EOs against B. cereus, S. aureus, P. aeruginosa, and E. coli, and lovage/basil EOs against B. cereus and E. coli. Combinations of parsley/lovage and parsley/basil EOs exhibited indifferent effects against all bacteria. The combination of lovage/basil EO showed indifferent effect against S. aureus, P. aeruginosa, and S. typhimurium, and the combination parsley/thyme EO against S. typhimurium. Thyme EO has the highest percentage yield and antibacterial potential from all tested formulations; its combination with parsley, lovage, and basil EOs determines a reduction of its antibacterial activity. Hence, it is recommended to be used alone as the antibacterial agent.

  19. Antibacterial activity and interactions of plant essential oil combinations against Gram-positive and Gram-negative bacteria.

    Science.gov (United States)

    Semeniuc, Cristina Anamaria; Pop, Carmen Rodica; Rotar, Ancuţa Mihaela

    2017-04-01

    The aim of this study was to compare the antibacterial effects of several essential oils (EOs) alone and in combination against different Gram-positive and Gram-negative bacteria associated with food products. Parsley, lovage, basil, and thyme EOs, as well as their mixtures (1:1, v/v), were tested against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhimurium. The inhibitory effects ranged from strong (thyme EO against E. coli) to no inhibition (parsley EO against P. aeruginosa). Thyme EO exhibited strong (against E. coli), moderate (against S. typhimurium and B. cereus), or mild inhibitory effects (against P. aeruginosa and S. aureus), and basil EO showed mild (against E. coli and B. cereus) or no inhibitory effects (against S. typhimurium, P. aeruginosa, and S. aureus). Parsley and lovage EOs revealed no inhibitory effects against all tested strains. Combinations of lovage/thyme and basil/thyme EOs displayed antagonistic effects against all bacteria, parsley/thyme EOs against B. cereus, S. aureus, P. aeruginosa, and E. coli, and lovage/basil EOs against B. cereus and E. coli. Combinations of parsley/lovage and parsley/basil EOs exhibited indifferent effects against all bacteria. The combination of lovage/basil EO showed indifferent effect against S. aureus, P. aeruginosa, and S. typhimurium, and the combination parsley/thyme EO against S. typhimurium. Thyme EO has the highest percentage yield and antibacterial potential from all tested formulations; its combination with parsley, lovage, and basil EOs determines a reduction of its antibacterial activity. Hence, it is recommended to be used alone as the antibacterial agent. Copyright © 2016. Published by Elsevier B.V.

  20. Evaluating the resistance pattern of gram-negative bacteria during three years at the nephrology ward of a referral hospital in southwest of Iran.

    Science.gov (United States)

    Karimzadeh, Iman; Sadeghimanesh, Niloofar; Mirzaee, Mona; Sagheb, Mohammad Mahdi

    2017-07-01

    Gram-negative bacteria are associated with an increase in rates of antibacterial resistance. In most low- and middle-income countries such as Iran, there is no continuous surveillance system for antibiotic resistance. The purpose of this survey was to determine the pattern of antimicrobial sensitivity of gram-negative bacteria within 3 consecutive years at a nephrology ward of Nemazee hospital in Shiraz. During a 3-year period from 2013 to 2015 at the adult nephrology ward, bacteriological data of all biological samples of hospitalized patients in favor of gram-negative microorganisms were analyzed retrospectively. Antimicrobial susceptibility was performed by the Kirby-Bauer disc diffusion method. The most common gram negative bacterium isolated from biological samples was Escherichia coli (43.9%). The highest (86.3%-94.1%) antibacterial resistance rate was associated with Acinetobacter spp. The most frequent resistance was seen with cephalosporins. In contrast to ceftriaxone, ciprofloxacin, and trimethoprim/sulfamethoxazole, nitrofurantoin and aminoglycosides remained their acceptable activity against E. coli. At least three-fourths (75%) of Acinetobacter spp. isolates was resistant to either aminoglycosides or imipenem. All (100%) isolated Acinetobacter spp. and Pseudomonas aeruginosa species were susceptible to colistin. The rate of Acinetobacter spp. and P. aeruginosa resistant to three or more drugs was 81.7% and 74.6%, respectively. The resistant rate of gram negative pathogens to different tested antibacterial agents was considerably high and has increased during the recent three years in our center.

  1. Rapid Detection of Antibiotic Resistance in Gram-Negative Bacteria Through Assessment of Changes in Cellular Morphology.

    Science.gov (United States)

    Otero, Fátima; Santiso, Rebeca; Tamayo, Maria; Fernández, José Luis; Bou, Germán; Lepe, José Antonio; McConnell, Michael J; Gosálvez, Jaime; Cisneros, José Miguel

    2017-03-01

    Rapid antimicrobial susceptibility testing has the potential to improve patient outcomes and reduce healthcare-associated costs. In this study, a novel assay based on bacterial cell elongation after exposure to an antibiotic (ceftazidime) was evaluated for its ability to rapidly detect resistance in Gram-negative bacteria. The assay was used to detect resistance in a large collection of strains containing 320 clinical isolates of Acinetobacter baumannii, 171 clinical isolates of Klebsiella pneumoniae, and 212 clinical isolates of Pseudomonas aeruginosa, and the results were compared to those obtained using standard antimicrobial susceptibility testing methods. The assay identified ceftazidime-resistant strains with 100% sensitivity and 100% specificity for A. baumannii, 100% sensitivity and 97.2% specificity for K. pneumoniae, and with 82.3% sensitivity and 100% specificity for P. aeruginosa. Importantly, results were obtained in 1 hour 15 minutes from exponentially growing cultures. This study demonstrates that changes in cell length are highly correlated with phenotypic antibiotic susceptibility determined using standard susceptibility testing methods. This study therefore provides proof-of-concept that changes in cell morphology can be used as the basis for rapid detection of antibiotic resistance and provides the basis for the development of novel rapid diagnostics for the detection of antibiotic resistance.

  2. Endonuclease from Gram-Negative Bacteria Serratia marcescens Is as Effective as Pulmozyme in the Hydrolysis of DNA in Sputum

    Science.gov (United States)

    Vafina, Gulnaz; Zainutdinova, Elmira; Bulatov, Emil; Filimonova, Maria N.

    2018-01-01

    One of the approaches to effective airway cleansing is the degradation of DNA into smaller fragments. For this purpose Pulmozyme® is used with high efficacy because it contains recombinant DNase I as its active component. The aim of the study was to comparatively analyze DNase activity of Pulmozyme® and the nuclease from gram-negative bacteria Serratia marcescens, because at optimal conditions the catalytic efficiency of the nuclease is much higher than the efficiency of DNase I. Highly polymerized DNA and purulent-mucous sputum were used as substrates. The examination showed that both S. marcescens nuclease and Pulmozyme® hydrolyzed DNA in sputum. Also S. marcescens nuclease was found capable of hydrolyzing DNA in conditions that are standard for Pulmozyme® and suitable for its therapeutic application. For manifesting the similar hydrolytic activity the nuclease amount in the assay mixture containing highly polymerized DNA or the sonicated sputum and NaCl together with calcium- or magnesium- cations can be about 10- time lower than that of the recombinant DNase I. In the presence of magnesium cations the DNase activity of both S. marcescens nuclease and Pulmozyme® was higher than in the presence of calcium cations. PMID:29503617

  3. Controlled Synthesis of Gold Nanoparticles Using Aspergillus terreus IF0 and Its Antibacterial Potential against Gram Negative Pathogenic Bacteria

    International Nuclear Information System (INIS)

    Priyadarshini, E.; Pradhan, N.; Sukla, L.B.; Panda, P.K.; Pradhan, N.

    2014-01-01

    Biosynthesis of monodispersed nanoparticles, along with determination of potential responsible biomolecules, is the major bottleneck in the area of bio nano technology research. The present study focuses on an eco friendly, ambient temperature protocol for size controlled synthesis of gold nanoparticles, using the fungus Aspergillus terreus IF0. Gold nanoparticles were formed immediately, with the addition of chloroauric acid to the aqueous fungal extract. Synthesized nanoparticles were characterized by UV-Vis spectroscopy, TEM-EDX, and XRD analysis. Particle diameter and dispersity of nanoparticles were controlled by varying the ph of the fungal extract. At ph 10, the average size of the synthesized particles was in the range of 10–19 nm. Dialysis to obtain high and low molecular weight fraction followed by FTIR analysis revealed that biomolecules larger than 12 kDa and having –CH, –NH, and –SH functional groups were responsible for bioreduction and stabilization. In addition, the synthesized gold nanoparticles were found to be selectively bactericidal against the pathogenic gram negative bacteria, Escherichia coli.

  4. Preparation and evaluation of antibacterial potential of Pithecellobium dulce root extract against Gram positive and Gram negative bacteria.

    Science.gov (United States)

    Bhat, Muneer Ahmad; Malik, Rayees Ahmad; Prakash, Poonam; Lone, Ali Mohd

    2018-03-01

    In the present study hexane, benzene, ethyl acetate and ethanol extracts of Pithecellobium dulce root were prepared using soxhlet extractor. The extracts were evaluated for antibacterial activity against one Gram positive (Staphylococcus aureus) and three Gram negative (Acetobacter aceti, Acetobacter aceti, Klebsiella pneumoniae) strains. Disc diffusion method revealed promising antibacterial activity of the extracts prepared in polar solvents (ethyl acetate and ethanol) compared to non-polar solvents (hexane and benzene). Ethanolic root extract was found to be most active against Acetobacter aceti, Staphylococcus aureus, Klebsiella pneumonia and Enterobacter aerogenes bacterial strains. The zone of inhibition of ethanolic root extract against Acetobacter aceti, Staphylococcus aureus, Klebsiella pneumonia and Enterobacter aerogenes bacterial strains was 15.4, 11.0, 19.0 and 13.0 mm, respectively at 100 mg concentration. Ethyl acetate extract also exhibited good antibacterial activity against Entrobacter aerogenes, Klebsiella pneumonia and Acetobacter aceti. The zone of inhibition of ethyl acetate root extracts against Entrobacter aerogenes, Acetobacter aceti and Klebsiella pneumonia was 10.5, 18.0 and 10.0 mm, respectively. The benzene extract showed some activity against Acetobacter aceti with the zone of inhibition 10.0 mm. The antibacterial activity of Pithecellobium dulce root hexane extract was found to be negligible against all the four tested strains of bacteria. These findings suggest that ethanolic and ethyl acetate root extracts of Pithecellobium dulce has potential as effective anti-bacterial agent. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Co-selection of antibiotic and metal(loid) resistance in gram-negative epiphytic bacteria from contaminated salt marshes.

    Science.gov (United States)

    Henriques, Isabel; Tacão, Marta; Leite, Laura; Fidalgo, Cátia; Araújo, Susana; Oliveira, Cláudia; Alves, Artur

    2016-08-15

    The goal of this study was to investigate co-selection of antibiotic resistance in gram-negative epiphytic bacteria. Halimione portulacoides samples were collected from metal(loid)-contaminated and non-contaminated salt marshes. Bacterial isolates (n=137) affiliated with Vibrio, Pseudomonas, Shewanella, Comamonas, Aeromonas and with Enterobacteriaceae. Vibrio isolates were more frequent in control site while Pseudomonas was common in contaminated sites. Metal(loid) and antibiotic resistance phenotypes varied significantly according to site contamination, and multiresistance was more frequent in contaminated sites. However, differences among sites were not observed in terms of prevalence or diversity of acquired antibiotic resistance genes, integrons and plasmids. Gene merA, encoding mercury resistance, was only detected in isolates from contaminated sites, most of which were multiresistant to antibiotics. Results indicate that metal(loid) contamination selects for antibiotic resistance in plant surfaces. In salt marshes, antibiotic resistance may be subsequently transferred to other environmental compartments, such as estuarine water or animals, with potential human health risks. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Dose-Dependent Antimicrobial Activity of Silver Nanoparticles on Polycaprolactone Fibers against Gram-Positive and Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Erick Pazos-Ortiz

    2017-01-01

    Full Text Available The adhesion ability and adaptability of bacteria, coupled with constant use of the same bactericides, have made the increase in the diversity of treatments against infections necessary. Nanotechnology has played an important role in the search for new ways to prevent and treat infections, including the use of metallic nanoparticles with antibacterial properties. In this study, we worked on the design of a composite of silver nanoparticles (AgNPS embedded in poly-epsilon-caprolactone nanofibers and evaluated its antimicrobial properties against various Gram-positive and Gram-negative microorganisms associated with drug-resistant infections. Polycaprolactone-silver composites (PCL-AgNPs were prepared in two steps. The first step consisted in the reduction in situ of Ag+ ions using N,N-dimethylformamide (DMF in tetrahydrofuran (THF solution, and the second step involved the simple addition of polycaprolactone before electrospinning process. Antibacterial activity of PCL-AgNPs nanofibers against E. coli, S. mutans, K. pneumoniae, S. aureus, P. aeruginosa, and B. subtilis was evaluated. Results showed sensibility of E. coli, K. pneumoniae, S. aureus, and P. aeruginosa, but not for B. subtilis and S. mutans. This antimicrobial activity of PCL-AgNPs showed significant positive correlations associated with the dose-dependent effect. The antibacterial property of the PCL/Ag nanofibers might have high potential medical applications in drug-resistant infections.

  7. A new class of quorum quenching molecules from Staphylococcus species affects communication and growth of gram-negative bacteria.

    Directory of Open Access Journals (Sweden)

    Ya-Yun Chu

    Full Text Available The knowledge that many pathogens rely on cell-to-cell communication mechanisms known as quorum sensing, opens a new disease control strategy: quorum quenching. Here we report on one of the rare examples where Gram-positive bacteria, the 'Staphylococcus intermedius group' of zoonotic pathogens, excrete two compounds in millimolar concentrations that suppress the quorum sensing signaling and inhibit the growth of a broad spectrum of Gram-negative beta- and gamma-proteobacteria. These compounds were isolated from Staphylococcus delphini. They represent a new class of quorum quenchers with the chemical formula N-[2-(1H-indol-3-ylethyl]-urea and N-(2-phenethyl-urea, which we named yayurea A and B, respectively. In vitro studies with the N-acyl homoserine lactone (AHL responding receptor LuxN of V. harveyi indicated that both compounds caused opposite effects on phosphorylation to those caused by AHL. This explains the quorum quenching activity. Staphylococcal strains producing yayurea A and B clearly benefit from an increased competitiveness in a mixed community.

  8. Rapid discrimination of Gram-positive and Gram-negative bacteria in liquid samples by using NaOH-sodium dodecyl sulfate solution and flow cytometry.

    Directory of Open Access Journals (Sweden)

    Atsushi Wada

    Full Text Available BACKGROUND: For precise diagnosis of urinary tract infections (UTI, and selection of the appropriate prescriptions for their treatment, we explored a simple and rapid method of discriminating gram-positive and gram-negative bacteria in liquid samples. METHODOLOGY/PRINCIPAL FINDINGS: We employed the NaOH-sodium dodecyl sulfate (SDS solution conventionally used for plasmid extraction from Escherichia coli and the automated urine particle analyzer UF-1000i (Sysmex Corporation for our novel method. The NaOH-SDS solution was used to determine differences in the cell wall structures between gram-positive and gram-negative bacteria, since the tolerance to such chemicals reflects the thickness and structural differences of bacterial cell walls. The UF-1000i instrument was used as a quantitative bacterial counter. We found that gram-negative bacteria, including E. coli, in liquid culture could easily be lysed by direct addition of equal volumes of NaOH-SDS solution. In contrast, Enterococcus faecalis, which is a gram-positive bacterium, could not be completely lysed by the solution. We then optimized the reaction time of the NaOH-SDS treatment at room temperature by using 3 gram-positive and 4 gram-negative bacterial strains and determined that the optimum reaction time was 5 min. Finally, in order to evaluate the generalizability of this method, we treated 8 gram-positive strains and 8 gram-negative strains, or 4 gram-positive and 4 gram-negative strains incubated in voluntary urine from healthy volunteers in the same way and demonstrated that all the gram-positive bacteria were discriminated quantitatively from gram negative bacteria using this method. CONCLUSIONS/SIGNIFICANCE: Using our new method, we could easily discriminate gram-positive and gram-negative bacteria in liquid culture media within 10 min. This simple and rapid method may be useful for determining the treatment course of patients with UTIs, especially for those without a prior history

  9. Battacin (Octapeptin B5), a new cyclic lipopeptide antibiotic from Paenibacillus tianmuensis active against multidrug-resistant Gram-negative bacteria.

    Science.gov (United States)

    Qian, Chao-Dong; Wu, Xue-Chang; Teng, Yi; Zhao, Wen-Peng; Li, Ou; Fang, Sheng-Guo; Huang, Zhao-Hui; Gao, Hai-Chun

    2012-03-01

    Hospital-acquired infections caused by drug-resistant bacteria are a significant challenge to patient safety. Numerous clinical isolates resistant to almost all commercially available antibiotics have emerged. Thus, novel antimicrobial agents, specifically those for multidrug-resistant Gram-negative bacteria, are urgently needed. In the current study, we report the isolation, structure elucidation, and preliminary biological characterization of a new cationic lipopeptide antibiotic, battacin or octapeptin B5, produced from a Paenibacillus tianmuensis soil isolate. Battacin kills bacteria in vitro and has potent activity against Gram-negative bacteria, including multidrug-resistant and extremely drug-resistant clinical isolates. Hospital strains of Escherichia coli and Pseudomonas aeruginosa are the pathogens most sensitive to battacin, with MICs of 2 to 4 μg/ml. The ability of battacin to disrupt the outer membrane of Gram-negative bacteria is comparable to that of polymyxin B, the last-line therapy for infections caused by antibiotic-resistant Gram-negative bacteria. However, the capacity of battacin to permeate bacterial plasma membranes is less extensive than that of polymyxin B. The bactericidal kinetics of battacin correlate with the depolarization of the cell membrane, suggesting that battacin kills bacteria by disrupting the cytoplasmic membrane. Other studies indicate that battacin is less acutely toxic than polymyxin B and has potent in vivo biological activity against E. coli. Based on the findings of the current study, battacin may be considered a potential therapeutic agent for the treatment of infections caused by antibiotic-resistant Gram-negative bacteria.

  10. Architecture of class 1, 2 and 3 integrons from Gram negative bacteria recovered among fruits and vegetables.

    Directory of Open Access Journals (Sweden)

    Daniela Jones-Dias

    2016-09-01

    Full Text Available The spread of antibiotic resistant bacteria throughout the food chain constitutes a public health concern. To understand the contribution of fresh produce in shaping antibiotic resistance bacteria and integron prevalence in the food chain, 333 antibiotic resistance Gram negative isolates were collected from organic and conventionally produced fruits (pears, apples and strawberries and vegetables (lettuces, tomatoes and carrots. Although low levels of resistance have been detected, the bacterial genera identified in the assessed fresh produce are often described not only as environmental, but mostly as commensals and opportunistic pathogens. The genomic characterization of integron-harboring isolates revealed a high number of mobile genetic elements and clinically relevant antibiotic resistance genes, of which we highlight the presence of as mcr-1, qnrA1, blaGES-11, mphA and oqxAB. The study of class 1 (n=8, class 2 (n=3 and class 3 (n=1 integrons, harbored by species such as Morganella morganii, Escherichia coli, Klebsiella pneumoniae, led to the identification of different integron promoters (PcW, PcH1, PcS and PcWTNG-10 and cassette arrays (containing drfA, aadA, cmlA, estX, sat and blaGES. In fact, the diverse integron backbones were associated with transposable elements (e.g. Tn402, Tn7, ISCR1, Tn2*, IS26, IS1326 and IS3 that conferred greater mobility. This is also the first appearance of In1258, In1259 and In3-13, which should be monitored to prevent their establishment as successfully dispersed mobile resistance integrons. These results underscore the growing concern about the dissemination of acquired resistance genes by mobile elements in the food chain.

  11. Flow cytometric evaluation of physico-chemical impact on Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Antje eFröhling

    2015-09-01

    Full Text Available Since heat sensitivity of fruits and vegetables limits the application of thermal inactivation processes, new emerging inactivation technologies have to be established to fulfil the requirements of food safety without affecting the produce quality. The efficiency of inactivation treatments has to be ensured and monitored. Monitoring of inactivation effects is commonly performed using traditional cultivation methods which have the disadvantage of the time span needed to obtain results.The aim of this study was to compare the inactivation effects of peracetic acid (PAA, ozonated water (O3 and cold atmospheric pressure plasma (CAPP on Gram-positive and Gram-negative bacteria using flow cytometric methods. E. coli cells were completely depolarized after treatment (15 s with 0.25 % PAA at 10 °C, and after treatment (10 s with 3.8 mg l-1 O3 at 12°C. The membrane potential of CAPP treated cells remained almost constant at an operating power of 20 W over a time period of 3 min, and subsequently decreased within 30 s of further treatment. Complete membrane permeabilization was observed after 10 s O3 treatment, but treatment with PAA and CAPP did not completely permeabilize the cells within 2 min and 4 min, respectively. Similar results were obtained for esterase activity. O3 inactivates cellular esterase but esterase activity was detected after 4 min CAPP treatment and 2 min PAA treatment. L. innocua cells and P. carotovorum cells were also permeabilized instantaneously by O3 treatment at concentrations of 3.8 ± 1 mg l-1. However, higher membrane permeabilization of L. innocua and P. carotovorum than of E. coli was observed at CAPP treatment of 20 W. The degree of bacterial damage due to the inactivation processes is highly dependent on treatment parameters as well as on treated bacteria. Important information regarding the inactivation mechanisms can be obtained by flow cytometric measurements and this enables the definition of critical process

  12. Development of a miniaturised microarray-based assay for the rapid identification of antimicrobial resistance genes in Gram-negative bacteria

    NARCIS (Netherlands)

    Batchelor, M.; Hopkins, K.L.; Liebana, E.; Slickers, P.; Ehricht, R.; Mafura, M.; Aerestrup, F.; Mevius, D.J.; Clifton-Hadley, F.A.; Woodward, M.; Davies, R.; Threlfall, J.; Anjum, F.M.

    2008-01-01

    We describe the development of a miniaturised microarray for the detection of antimicrobial resistance genes in Gram-negative bacteria. Included on the array are genes encoding resistance to aminoglycosides, trimethoprim, sulphonamides, tetracyclines and ß-lactams, including extended-spectrum

  13. Methods for detecting acylated homoserine lactones produced by Gram-negative bacteria and their application in studies of AHL- production kinetics

    DEFF Research Database (Denmark)

    Ravn, L.; Christensen, Allan Beck; Molin, Søren

    2001-01-01

    In the process of evaluating the role of acylated homoserine lactones (AHLs) in food-spoiling Gram-negative bacteria, we have combined a range of bacterial AHL monitor systems to determine the AHL-profile and the kinetics of AHL-production. AHL production from 148 strains of Enterobacteriaceae is...

  14. Photocatalytic degradation of methylene blue and inactivation of gram-negative bacteria by TiO2 nanoparticles in aqueous suspension

    Science.gov (United States)

    The photocatalytic degradation of methylene blue (MB) and inactivation of Gram-negative bacteria E. coli K12 and P. aeruginosa by TiO2 nanoparticles in aqueous suspension were studied. TiO2 resulted in significant reduction in MB absorption and a shift of MB absorption peak from 664 nm to 658 nm aft...

  15. Comparative activity of tigecycline and tetracycline on Gram-negative and Gram-positive bacteria revealed by a multicentre study in four North European countries

    DEFF Research Database (Denmark)

    Nilsson, Lennart E; Frimodt-Møller, Niels; Vaara, Martti

    2011-01-01

    This study involves a multicentre surveillance of tigecycline and tetracycline activity against Gram-negative and Gram-positive bacteria from primary care centres (PCCs), general hospital wards (GHWs) and intensive care units (ICUs) in Denmark (n = 9), Finland (n = 10), Norway (n = 7) and Sweden (n...

  16. Array based detection of antibiotic resistance genes in Gram negative bacteria isolated from retail poultry meat in the UK and Ireland.

    Science.gov (United States)

    McNeece, Grainne; Naughton, Violetta; Woodward, Martin J; Dooley, James S G; Naughton, Patrick J

    2014-06-02

    The use of antibiotics in birds and animals intended for human consumption within the European Union (EU) and elsewhere has been subject to regulation prohibiting the use of antimicrobials as growth promoters and the use of last resort antibiotics in an attempt to reduce the spread of multi-resistant Gram negative bacteria. Given the inexorable spread of antibiotic resistance there is an increasing need for improved monitoring of our food. Using selective media, Gram negative bacteria were isolated from retail chicken of UK-Intensively reared (n=27), Irish-Intensively reared (n=19) and UK-Free range (n=30) origin and subjected to an oligonucleotide based array system for the detection of 47 clinically relevant antibiotic resistance genes (ARGs) and two integrase genes. High incidences of β-lactamase genes were noted in all sample types, acc (67%), cmy (80%), fox (55%) and tem (40%) while chloramphenicol resistant determinants were detected in bacteria from the UK poultry portions and were absent in bacteria from the Irish samples. Denaturing Gradient Gel Electrophoresis (DGGE) was used to qualitatively analyse the Gram negative population in the samples and showed the expected diversity based on band stabbing and DNA sequencing. The array system proved to be a quick method for the detection of antibiotic resistance gene (ARG) burden within a mixed Gram negative bacterial population. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. A New Take on an Old Remedy: Generating Antibodies against Multidrug-Resistant Gram-Negative Bacteria in a Postantibiotic World.

    Science.gov (United States)

    Motley, Michael P; Fries, Bettina C

    2017-01-01

    With the problem of multidrug-resistant Gram-negative pathogens becoming increasingly dire, new strategies are needed to protect and treat infected patients. Though abandoned in the past, monoclonal antibody therapy against Gram-negative bacteria remains a potential solution and has potential advantages over the broad-spectrum antibiotics they were once replaced by. This Perspective reviews the prospect of utilizing monoclonal antibody therapy against these pathogens, as well as the challenges of doing so and the current therapy targets under investigation.

  18. Studies on reproductive stress caused by candidate Gram positive and Gram negative bacteria using model organism, Caenorhabditis elegans.

    Science.gov (United States)

    Sharika, Rajasekharan; Subbaiah, Priya; Balamurugan, Krishnaswamy

    2018-04-05

    Microbial association with a host using model system C. elegans have been widely studied based on factors such as host survival, the mode of infection, disease pathogenesis and the role of various players regulated during infection. The influence of pathogenic microorganism on reproduction and associated issues has not been explored fully. The present study focuses on the impact of bacterial infection on male reproductive parameters such as spermatogenesis and spermiogenesis, including physiological aspects like tail morphology defect and underlying molecular mechanisms that have been perturbed. In order to compare the consequence of infection caused by Gram positive and negative bacteria, Staphylococcus aureus and Vibrio alginolyticus were chosen as candidate pathogens, respectively. Microscopic observations revealed notable changes in tail morphology during 24 h of infection, as along with change in sperm size and activation. The Real Time-PCR results suggest the plausible down regulation of DBL-1/TGF-β pathway suggesting the morphological change in the tail. Shotgun proteomics further lead to the identification of MAG-1, Magonashi Protein a candidate regulatory player that affects spermatogenesis and HIF-1 that regulate during stress in both Gram positive and Gram negative infection. The protein-protein interaction with detected proteins revealed RACK-1 protein and mTOR pathway in S. aureus and V. alginolyticus respectively interacting with MAG-1 protein, which plays an important role in spermatogenesis termination in hermaphrodites during L4 to adult switch. This study paves a way to understand the candidate players that regulate reproduction during bacterial infection. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Antimicrobial Activity of Carbon Nanoparticles Isolated from Natural Sources against Pathogenic Gram-Negative and Gram-Positive Bacteria

    Directory of Open Access Journals (Sweden)

    Sheena Varghese

    2013-01-01

    Full Text Available This paper describes the isolation of carbon nanoparticles (CNPs from kitchen soot, characterization of the CNPs by UV/visible spectroscopy, SEM and XRD, and their antimicrobial action. The antibacterial activity of the isolated carbon nanoparticles was tested against various pathogenic bacterial strains such as Gram-negative Proteus refrigere and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus and Streptococcus haemolyticus. The inhibition zones were measured, and it was found that the carbon nanoparticles isolated from natural sources are active against these Gram-negative and Gram-positive bacterial strains.

  20. Bactérias gram negativas resistentes a antimicrobianos em alimentos Gram-negative bacteria resistant to antibiotics in foods

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    José Cavalcante de Albuquerque Ribeiro Dias

    1985-12-01

    Full Text Available A partir de 154 espécimens de alimentos, representados por hortaliças (alface, leite e merenda escolar, obteve-se o isolamento e identificação de 400 amostras de bacilos Gram negativos. Esta amostragem se distribuiu em 339 enterobactérias (Escherichia, Shigella, Citrobacter, Klebsiella, Enterobacter, Serratia e Proteus e 61 de gêneros afins (Acinetobacter, Flavobacterium, Aeromonas e Pseudomonas. Submetendo-se as culturas aos antimicrobianos: sulfadiazina (Su, estreptomicina (Sm, tetraciclina (Tc, cloranfenicol (Cm, canamicina (Km, ampicilina (Ap, ácido nalidíxico (Nal e gentamicina (Gm, observou-se apenas seis estirpes sensíveis a todas as drogas e sensibilidade absoluta à Gm. A predominância dos modelos Su (27,6% e Su-Ap (39,6% incidiu nas enterobactérias, enquanto que, 18,0% para Ap e 9,8% para Su-Ap foram detectados nos gêneros afins. Para caracterização da resistência foram realizados testes de conjugação e a totalidade das culturas não revelou transferência para o gene que confere resistência ao ácido nalidíxico. Relevantes são as taxas de amostras R+ observadas nos bacilos entéricos, oscilando em torno de 90% (leite e merenda escolar e alface, em torno de 70%From 154 food samples, including vegetables (lettuce, milk and meals served at school it was possible to isolate and identify 400 Gram negative bacilli distributed among 339 enteric bacteria (Escherichia, Shigella, Citrobacter, Klebsiella, Enterobacter, Serratia and Proteus and other 61 non enteric bacilli (Acinetobacter, Flavobacterium, Aeromonas and Pseudomonas. Submitting this cultures to the drugs sulfadiazine (Su, streptomycin (Sm, tetracycline (Tc, chloramphenicol (Cm, kanamycin (Km, ampicillin (Ap, nalidixic acid (Nal and gentamycin (Gm it was observed only six stocks susceptible to all drugs and total sensibility to Gm. Among enteric bacteria the profiles Su (27,6% and Su-Ap (39,6% predominated, while for the non enteric bacilli percentages of 18.0 for

  1. Monomicrobial necrotizing fasciitis in a single center: the emergence of Gram-negative bacteria as a common pathogen

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    D. Yahav

    2014-11-01

    Conclusions: In our center, 42% of monomicrobial necrotizing fasciitis cases were found to be caused by Gram-negative organisms, mostly E. coli. These infections usually appeared in immunocompromised or postoperative patients, often presented with normal CPK levels, and were associated with high mortality rates.

  2. Prevalence and antibacterial resistance patterns of extended-spectrum beta-lactamase producing Gram-negative bacteria isolated from ocular infections

    Directory of Open Access Journals (Sweden)

    G Rameshkumar

    2016-01-01

    Full Text Available Purpose: Extended-spectrum beta-lactamases (ESBLs mediated resistance is more prevalent worldwide, especially among Gram-negative bacterial isolates, conferring resistance to the expanded spectrum cephalosporins. As limited data were available on the prevalence of ESBLs in this area, the current study was undertaken to determine the prevalence, antibacterial resistance patterns, and molecular detection and characterization of ESBL encoding resistance genes among ocular Gram-negative bacterial isolates from ocular infections. Materials and Methods: A prospective study was done on 252 ocular Gram-negative bacterial isolates recovered from ocular infections during a study period from February 2011 to January 2014. All isolates were subjected to detection of ESBLs by cephalosporin/clavulanate combination disc test and their antibacterial resistance pattern was studied. Molecular detection and characterization of ESBL encoding blaTEM -, blaSHV , blaOXA -, and blaCTX-M (phylogenetic groups 1, 2, 9, and 8/25 resistance genes by multiplex polymerase chain reaction and DNA sequence analysis. Results: Of all Gram-negative bacteria, Pseudomonas aeruginosa (44% was the most common strain, followed by Enterobacter agglomerans and Klebsiella pneumoniae each (10%. Among the 252, 42 (17% were ESBL producers. The major source of ESBL producers were corneal scraping specimens, highest ESBL production was observed in P. aeruginosa 16 (38% and Escherichia coli 7 (16.6%. Among ESBL-producing genes, the prevalence of blaTEM -gene was the highest (83% followed by blaOXA -gene (35%, blaSHV -gene (18.5%, and blaCTX-M-1 -gene (18.5% alone or together. Conclusion: The higher rate of prevalence of ESBLs-encoding genes among ocular Gram-negative bacteria is of great concern, as it causes limitation to therapeutic options. This regional knowledge will help in guiding appropriate antibiotic use which is highly warranted.

  3. Antagonistic activity of isolated lactic acid bacteria from Pliek U against gram-negative bacteria Escherichia coli ATCC 25922

    Science.gov (United States)

    Kiti, A. A.; Jamilah, I.; Rusmarilin, H.

    2017-09-01

    Lactic acid bacteria (LAB) is one group of microbes that has many benefits, notably in food and health industries sector. LAB plays an important role in food fermentation and it has bacteriostatic effect against the growth of pathogenic microorganisms. The research related LAB continued to be done to increase the diversity of potential isolates derived from nature which is indigenous bacteria for biotechnological purposes. This study was aimed to isolate and characterize LAB derived from pliek u sample and to examine the potency to inhibits Escherichia coli ATCC 25922 bacteria growth. A total of 5 isolates were isolated and based on morphological and physiological characteristics of the fifth bacteria, they are allegedly belonging to the genus Bacillus. Result of antagonistic test showed that the five isolates could inhibits the growth of E. coli ATCC 25922. The highest inhibition zone is 8.5 mm was shown by isolates NQ2, while the lowest inhibition is 1.5 mm was shown by isolates NQ3.

  4. Screening of antibiotic resistant gram negative bacteria and plasmid profiling of multi-drug resistant isolates present in sewage associated with health care centers

    OpenAIRE

    Khan Md. Anik Ashfaq, Sutradhar Pijush, Islam Mohammad Majharul, Ojha Ravi Kant, Biswas Gokul Chandra

    2013-01-01

    Background: Healthcare effluent acts as the store house of harmful infectious agents such as the pathogens and microorganisms possessing multiple drug resistant genes. Potential health risk includes spreading of diseases by these pathogens and wide dissemination of antimicrobial resistance genes. Gram-negative bacteria are particularly important for causing most of the hospital and community acquired infections. Aim: This study was carried out to highlight the incidence of antibiotic resistan...

  5. Detection and Antibiotic Susceptibility Pattern of Biofilm Producing Gram Positive and Gram Negative Bacteria Isolated From a Tertiary Care Hospital of Pakistan

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    Iqbal, M.

    2011-01-01

    Full Text Available Microorganisms adhere to non-living material or living tissue, and form biofilms made up of extracellular polymers/slime. Biofilm-associated microorganisms behave differently from free-floating bacteria with respect to growth rates and ability to resist antimicrobial treatments and therefore pose a public health problem. The objective of this study is to detect the prevalence of biofilm producers among Gram positive and Gram negative bacteria isolated from clinical specimens, and to study their antimicrobial susceptibility pattern. The study was carried out from October 2009 to March 2010, at the Department of Microbiology, Army Medical College/ National University of Sciences and Technology (NUST, Rawalpindi, Pakistan. Clinical specimens were received from various wards of a tertiary care hospital. These were dealt by standard microbiological procedures. Gram positive and Gram negative bacteria isolated were subjected to biofilm detection by congo red agar method (CRA. Antimicrobial susceptibility testing of those isolates, which showed positive results (slime production, was done according to the Kirby-Bauer disc diffusion technique. A total of 150 isolates were tested for the production of biofilm/slime. Among them, 81 isolates showed positive results. From these 81, 51 were Gram positive and 30 were Gram negative. All the 81(54% slime producers showed reduced susceptibility to majority of antibiotics. Bacterial biofilms are an important virulence factor associated with chronic nosocomial infection. Detection of biofilm forming organisms can help in appropriate antibiotic choice.

  6. MALDI-TOF identification of Gram-negative bacteria directly from blood culture bottles containing charcoal: Sepsityper® kits versus centrifugation-filtration method.

    Science.gov (United States)

    Riederer, Kathleen; Cruz, Kristian; Shemes, Stephen; Szpunar, Susan; Fishbain, Joel T

    2015-06-01

    Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry has dramatically altered the way microbiology laboratories identify clinical isolates. Direct blood culture (BC) detection may be hampered, however, by the presence of charcoal in BC bottles currently in clinical use. This study evaluates an in-house process for extraction and MALDI-TOF identification of Gram-negative bacteria directly from BC bottles containing charcoal. Three hundred BC aliquots were extracted by a centrifugation-filtration method developed in our research laboratory with the first 96 samples processed in parallel using Sepsityper® kits. Controls were colonies from solid media with standard phenotypic and MALDI-TOF identification. The identification of Gram-negative bacteria was successful more often via the in-house method compared to Sepsityper® kits (94.7% versus 78.1%, P≤0.0001). Our in-house centrifugation-filtration method was further validated for isolation and identification of Gram-negative bacteria (95%; n=300) directly from BC bottles containing charcoal. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Identification of gram-negative bacteria from critical control points of raw and pasteurized cow milk consumed at Gondar town and its suburbs, Ethiopia.

    Science.gov (United States)

    Garedew, Legesse; Berhanu, Ayalew; Mengesha, Desalegne; Tsegay, Getachew

    2012-11-06

    Milk is highly prone to contamination and can serve as an efficient vehicle for human transmission of foodborne pathogens, especially gram-negative bacteria, as these are widely distributed in the environment. This cross-sectional study of gram-negative staining bacterial contamination of milk meant for human consumption was carried out from October 2010 to May 2011 in Gondar town, Ethiopia. Milk samples were collected from critical control points, from production to consumption, that were hypothesized to be a source of potential contamination. Milk sampling points included smallholder's milk producers, dairy co-operatives, a milk processing plant, and supermarkets. The hygienic procedures applied during milking, milk collection, transportation, pasteurization, and postpasteurization storage conditions at these specified critical control points were evaluated. Standard bacteriological cultivation and biochemical assays were used to isolate and identify bacterial pathogens in the milk samples. The results of the current study showed that conditions for contamination of raw milk at different critical points were due to less hygienic practices in pre-milking udder preparation, sub-optimal hygiene of milk handlers, and poor sanitation practices associated with milking and storage equipments. Among all critical control points considered, transportation containers at milk collection centers and at processing plants were found to be the most heavily contaminated with gram-negative staining bacterial species. Overall, 54 different bacterial species were indentified, and Escherichia coli (29.6%), Pseudomonas aeruginosa (18.5%), and Klebsiella pneumoniae (16.7%), were the most commonly identified gram-negative staining bacterial pathogens. Of particular interest was that no gram-negative staining bacteria were isolated from pasteurized milk samples with varying shelf life. This study showed the presence of diverse pathogenic gram-negative staining bacterial species in raw

  8. Identification of gram-negative bacteria from critical control points of raw and pasteurized cow milk consumed at Gondar town and its suburbs, Ethiopia

    Directory of Open Access Journals (Sweden)

    Garedew Legesse

    2012-11-01

    Full Text Available Abstract Background Milk is highly prone to contamination and can serve as an efficient vehicle for human transmission of foodborne pathogens, especially gram-negative bacteria, as these are widely distributed in the environment. Methods This cross-sectional study of gram-negative staining bacterial contamination of milk meant for human consumption was carried out from October 2010 to May 2011 in Gondar town, Ethiopia. Milk samples were collected from critical control points, from production to consumption, that were hypothesized to be a source of potential contamination. Milk sampling points included smallholder’s milk producers, dairy co-operatives, a milk processing plant, and supermarkets. The hygienic procedures applied during milking, milk collection, transportation, pasteurization, and postpasteurization storage conditions at these specified critical control points were evaluated. Standard bacteriological cultivation and biochemical assays were used to isolate and identify bacterial pathogens in the milk samples. Results The results of the current study showed that conditions for contamination of raw milk at different critical points were due to less hygienic practices in pre-milking udder preparation, sub-optimal hygiene of milk handlers, and poor sanitation practices associated with milking and storage equipments. Among all critical control points considered, transportation containers at milk collection centers and at processing plants were found to be the most heavily contaminated with gram-negative staining bacterial species. Overall, 54 different bacterial species were indentified, and Escherichia coli (29.6%, Pseudomonas aeruginosa (18.5%, and Klebsiella pneumoniae (16.7%, were the most commonly identified gram-negative staining bacterial pathogens. Of particular interest was that no gram-negative staining bacteria were isolated from pasteurized milk samples with varying shelf life. Conclusion This study showed the presence of

  9. Retrospective Analysis of Blood Stream Infections and Antibiotic Susceptibility Pattern of Gram Negative Bacteria in a Tertiary Care Cancer Hospital

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    Radha Rani D

    2017-12-01

    Full Text Available Background: Bacterial bloodstream infections are important causes of morbidity and mortality globally. The aim of the present study was to determine the bacterial profile of bloodstream infections and their antibiotic susceptibility pattern among the clinically diagnosed cases of sepsis in cancer patients. Methods: In the present study, etiological and antimicrobial susceptibility profile of blood cultures over a period of 1 year at a tertiary cancer care hospital was done. Blood culture positive isolates were identified using standard microbiological methods and by Fully automated BD Phoenix 100. The antibiotic susceptibility pattern of the organisms was performed by Kirby-Bauer disc diffusion method and MIC (Minimum inhibitory concentration was done by Fully automated BD Phoenix 100. Results: There were 1178 blood culture samples, of which 327 (27.7% were identified to be culture positive. Out of 327 positive cultures, 299 (91.4% showed bacterial growth, Gram negative were 161 (53.8% and Gram positive were 138 (46.1%. Candida species were isolated from 13 (3.97% of positive samples and 15 samples showed contamination. The most common Gram-negative isolate was. Escherichia coli (37.80% and Gram-positive isolate was coagulasenegative staphylococci (52.80%. Escherichia coli showed highest sensitivity to amikacin (83.60% and sensitivity to piperacillin+ tazobactum and cefaperazone+sulbactam was 54.09% and 52.45% respectively. High degree of resistance was found to cephalosporins and levofloxacin. Conclusion: The results indicate high level of antimicrobial resistance among Gram negative bacilli in septicemic patients. The results warrant continuous monitoring of antimicrobial pattern so as to build geographical epidemiological data.

  10. Transferable integrons of Gram-negative bacteria isolated from the gut of a wild boar in the buffer zone of a national park.

    Science.gov (United States)

    Mokracka, Joanna; Koczura, Ryszard; Kaznowski, Adam

    2012-06-01

    The aim of this study was to determine the presence of integron-bearing Gram-negative bacteria in the gut of a wild boar (Sus scrofa L.) shot in the buffer zone of a national park. Five Gram-negative strains of Escherichia coli, Serratia odorifera, Hafnia alvei and Pseudomonas sp. were isolated. Four of these strains had class 2 integrase (intI2), and one harbored class 1 integrase (intI1). The integron-positive strains were multiresistant, i.e., resistant to at least three unrelated antibiotics. All of the integrons were transferred to E. coli J-53 (Rif(R)) in a conjugation assay. The results showed that a number of multiresistant, integron-containing bacterial strains of different genera may inhabit a single individual of a wild animal, allowing the possibility of transfer of antimicrobial resistance genes.

  11. The Impact of Efflux Pump Inhibitors on the Activity of Selected Non-Antibiotic Medicinal Products against Gram-Negative Bacteria

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    Agnieszka E. Laudy

    2017-01-01

    Full Text Available The potential role of non-antibiotic medicinal products in the treatment of multidrug-resistant Gram-negative bacteria has recently been investigated. It is highly likely that the presence of efflux pumps may be one of the reasons for the weak activity of non-antibiotics, as in the case of some non-steroidal anti-inflammatory drugs (NSAIDs, against Gram-negative rods. The activity of eight drugs of potential non-antibiotic activity, active substance standards, and relevant medicinal products were analysed with and without of efflux pump inhibitors against 180 strains of five Gram-negative rod species by minimum inhibitory concentration (MIC value determination in the presence of 1 mM MgSO4. Furthermore, the influence of non-antibiotics on the susceptibility of clinical strains to quinolones with or without PAβN (Phe-Arg-β-naphthylamide was investigated. The impacts of PAβN on the susceptibility of bacteria to non-antibiotics suggests that amitriptyline, alendronate, nicergoline, and ticlopidine are substrates of efflux pumps in Gram-negative rods. Amitriptyline/Amitriptylinum showed the highest direct antibacterial activity, with MICs ranging 100–800 mg/L against all studied species. Significant decreases in the MIC values of other active substances (acyclovir, atorvastatin, and famotidine tested with pump inhibitors were not observed. The investigated non-antibiotic medicinal products did not alter the MICs of quinolones in the absence and in the presence of PAβN to the studied clinical strains of five groups of species.

  12. Oral Gram-negative anaerobic bacilli as a reservoir of β-lactam resistance genes facilitating infections with multiresistant bacteria.

    Science.gov (United States)

    Dupin, Clarisse; Tamanai-Shacoori, Zohreh; Ehrmann, Elodie; Dupont, Anais; Barloy-Hubler, Frédérique; Bousarghin, Latifa; Bonnaure-Mallet, Martine; Jolivet-Gougeon, Anne

    2015-02-01

    Many β-lactamases have been described in various Gram-negative bacilli (Capnocytophaga, Prevotella, Fusobacterium, etc.) of the oral cavity, belonging to class A of the Ambler classification (CepA, CblA, CfxA, CSP-1 and TEM), class B (CfiA) or class D in Fusobacterium nucleatum (FUS-1). The minimum inhibitory concentrations of β-lactams are variable and this variation is often related to the presence of plasmids or other mobile genetic elements (MGEs) that modulate the expression of resistance genes. DNA persistence and bacterial promiscuity in oral biofilms also contribute to genetic transformation and conjugation in this particular microcosm. Overexpression of efflux pumps is facilitated because the encoding genes are located on MGEs, in some multidrug-resistant clinical isolates, similar to conjugative transposons harbouring genes encoding β-lactamases. All these facts lead us to consider the oral cavity as an important reservoir of β-lactam resistance genes and a privileged place for genetic exchange, especially in commensal strictly anaerobic Gram-negative bacilli. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  13. Top-Down LESA Mass Spectrometry Protein Analysis of Gram-Positive and Gram-Negative Bacteria

    Science.gov (United States)

    Kocurek, Klaudia I.; Stones, Leanne; Bunch, Josephine; May, Robin C.; Cooper, Helen J.

    2017-10-01

    We have previously shown that liquid extraction surface analysis (LESA) mass spectrometry (MS) is a technique suitable for the top-down analysis of proteins directly from intact colonies of the Gram-negative bacterium Escherichia coli K-12. Here we extend the application of LESA MS to Gram-negative Pseudomonas aeruginosa PS1054 and Gram-positive Staphylococcus aureus MSSA476, as well as two strains of E. coli (K-12 and BL21 mCherry) and an unknown species of Staphylococcus. Moreover, we demonstrate the discrimination between three species of Gram-positive Streptococcus ( Streptococcus pneumoniae D39, and the viridans group Streptococcus oralis ATCC 35037 and Streptococcus gordonii ATCC35105), a recognized challenge for matrix-assisted laser desorption ionization time-of-flight MS. A range of the proteins detected were selected for top-down LESA MS/MS. Thirty-nine proteins were identified by top-down LESA MS/MS, including 16 proteins that have not previously been observed by any other technique. The potential of LESA MS for classification and characterization of novel species is illustrated by the de novo sequencing of a new protein from the unknown species of Staphylococcus. [Figure not available: see fulltext.

  14. Trends of Bloodstream Infections in a University Greek Hospital during a Three-Year Period: Incidence of Multidrug-Resistant Bacteria and Seasonality in Gram-negative Predominance.

    Science.gov (United States)

    Kolonitsiou, Fevronia; Papadimitriou-Olivgeris, Matthaios; Spiliopoulou, Anastasia; Stamouli, Vasiliki; Papakostas, Vasileios; Apostolopoulou, Eleni; Panagiotopoulos, Christos; Marangos, Markos; Anastassiou, Evangelos D; Christofidou, Myrto; Spiliopoulou, Iris

    2017-07-06

    The aim of the study was to assess the epidemiology, the incidence of multidrug-resistant bacteria and bloodstream infections' (BSIs) seasonality in a university hospital. This retrospective study was carried out in the University General Hospital of Patras, Greece, during 2011-13 y. Blood cultures from patients with clinical presentation suggestive of bloodstream infection were performed by the BacT/ALERT System. Isolates were identified by Vitek 2 Advanced Expert System. Antibiotic susceptibility testing was performed by the disk diffusion method and E-test. Resistance genes (mecA in staphylococci; vanA/vanB/vanC in enterococci; bla KPC /bla VIM /bla NDM in Klebsiella spp.) were detected by PCR. In total, 4607 (9.7%) blood cultures were positive from 47451 sets sent to Department of Microbiology, representing 1732 BSIs. Gram-negative bacteria (52.3%) were the most commonly isolated, followed by Gram-positive (39.5%), fungi (6.6%) and anaerobes bacteria (1.8%). The highest contamination rate was observed among Gram-positive bacteria (42.3%). Among 330 CNS and 150 Staphylococcus aureus, 281 (85.2%) and 60 (40.0%) were mecA-positive, respectively. From 113 enterococci, eight were vanA, two vanB and two vanC-positives. Of the total 207 carbapenem-resistant Klebsiella pneumoniae (73.4%), 202 carried bla KPC , four bla KPC and bla VIM and one bla VIM . A significant increase in monthly BSIs' incidence was shown (R2: 0.449), which may be attributed to a rise of Gram-positive BSIs (R2: 0.337). Gram-positive BSIs were less frequent in spring (P period. The increasing incidence of BSIs can be attributed to an increase of Gram-positive BSI incidence, even though Gram-negative bacteria remained the predominant ones. Seasonality may play a role in the predominance of Gram-negative's BSI.

  15. Lactic Acid Bacteria Inducing a Weak Interleukin-12 and Tumor Necrosis Alpha Response in Human Dendritic Cells Inhibit Strongly Stimulating Lactic Acid Bacteria but Act Synergistically with Gram-Negative Bacteria

    DEFF Research Database (Denmark)

    Zeuthen, Louise Hjerrild; Christensen, Hanne Risager; Frøkiær, Hanne

    2006-01-01

    The development and maintenance of immune homeostasis indispensably depend on signals from the gut flora. Lactic acid bacteria (LAB), which are gram-positive (G+) organisms, are plausible significant players and have received much attention. Gram-negative (G-) commensals, such as members...

  16. Antimicrobial susceptibility of Gram-negative bacteria causing intra-abdominal infections in China: SMART China 2011.

    Science.gov (United States)

    Zhang, Hui; Yang, Qiwen; Xiao, Meng; Chen, Minjun; Badal, Robert E; Xu, Yingchun

    2014-01-01

    The Study for Monitoring Antimicrobial Resistance Trends program monitors the activity of antibiotics against aerobic and facultative Gram-negative bacilli (GNBs) from intra-abdominal infections (IAIs) in patients worldwide. In 2011, 1 929 aerobic and facultative GNBs from 21 hospitals in 16 cities in China were collected. All isolates were tested using a panel of 12 antimicrobial agents, and susceptibility was determined following the Clinical Laboratory Standards Institute guidelines. Among the Gram-negative pathogens causing IAIs, Escherichia coli (47.3%) was the most commonly isolated, followed by Klebsiella pneumoniae (17.2%), Pseudomonas aeruginosa (10.1%), and Acinetobacter baumannii (8.3%). Enterobacteriaceae comprised 78.8% (1521/1929) of the total isolates. Among the antimicrobial agents tested, ertapenem and imipenem were the most active agents against Enterobacteriaceae, with susceptibility rates of 95.1% and 94.4%, followed by amikacin (93.9%) and piperacillin/tazobactam (87.7%). Susceptibility rates of ceftriaxone, cefotaxime, ceftazidime, and cefepime against Enterobacteriaceae were 38.3%, 38.3%, 61.1%, and 50.8%, respectively. The leastactive agent against Enterobacteriaceae was ampicillin/sulbactam (25.9%). The extended-spectrum β-lactamase (ESBL) rates among E. coli, K. pneumoniae, Klebsiella oxytoca, and Proteus mirabilis were 68.8%, 38.1%, 41.2%, and 57.7%, respectively. Enterobacteriaceae were the major pathogens causing IAIs, and the most active agents against the study isolates (including those producing ESBLs) were ertapenem, imipenem, and amikacin. Including the carbapenems, most agents exhibited reduced susceptibility against ESBL-positive and multidrug-resistant isolates.

  17. Horizontal transfer of antibiotic resistance genes among gram negative bacteria in sewage and lake water and influence of some physico-chemical parameters of water on conjugation process.

    Science.gov (United States)

    Shakibaie, M R; Jalilzadeh, K A; Yamakanamardi, S M

    2009-01-01

    Transfer of antibiotic resistance genes among gram negative bacteria in sewage and lake water and easy access of these bacteria to the community are major environmental and public health concern. The aim of this study was to determine transfer of the antimicrobial resistance genes from resistant to susceptible gram negative bacteria in the sewage and lake water by conjugation process and to determine the influence of some physico-chemical parameters of sewage and lake water on the transfer of these resistance genes. For this reason, we isolated 20 liter of each sewage and lake water from coconut area within university campus and Lingambudi lake respectively in Mysore city, India, during monsoon season and studied different physical parameters of the water samples like pH, temperature, conductivity turbidity and color as well as chemical parameters like BOD, COD, field DO and total chloride ion. The gram negative bacteria were isolated and identified from the above water samples using microbiological and biochemical methods and their sensitivity to different antibiotics was determined by disc diffusion break point assay. Conjugation between two multiple antibiotic resistant isolates Pseudomonas aeuginosa and E. coli as donor and E. coli Rif(r) (sensitive to antibiotics) as recipient were carried out in 5ml sterile sewage and lake water. All isolates were resistant to Am, moderately resistant to Te and E, while majority were sensitive to Cip, Gm and CAZ antibiotics. Horizontal transfer of antibiotic resistance genes by conjugation process revealed transfer of Gm, Te and E resistant genes from Ps. aeruginosa to E. coli Rif(r) recipient with mean frequency of +/- 2.3 x 10(-4) in sewage and +/- 2.6 x 10(-6) in lake water respectively Frequency of conjugation in sewage was two fold more as compared to lake water (pbacteria by conjugation. Physico-chemical parameters of water may play role in this process.

  18. Evaluation of the in vitro growth of urinary tract infection-causing gram-negative and gram-positive bacteria in a proposed synthetic human urine (SHU) medium.

    Science.gov (United States)

    Ipe, Deepak S; Ulett, Glen C

    2016-08-01

    Bacteriuria is a hallmark of urinary tract infection (UTI) and asymptomatic bacteriuria (ABU), which are among the most frequent infections in humans. A variety of gram-negative and gram-positive bacteria are associated with these infections but Escherichia coli contributes up to 80% of cases. Multiple bacterial species including E. coli can grow in human urine as a means to maintain colonization during infections. In vitro bacteriuria studies aimed at modeling microbial growth in urine have utilized various compositions of synthetic human urine (SHU) and a Composite SHU formulation was recently proposed. In this study, we sought to validate the recently proposed Composite SHU as a medium that supports the growth of several bacterial species that are known to grow in normal human urine and/or artificial urine. Comparative growth assays of gram-negative and gram-positive bacteria E. coli, Pseudomonas aeruginosa, Proteus mirabilis, Streptococcus agalactiae, Staphylococcus saprophyticus and Enterococcus faecalis were undertaken using viable bacterial count and optical density measurements over a 48h culture period. Three different SHU formulations were tested in various culture vessels, shaking conditions and volumes and showed that Composite SHU can support the robust growth of gram-negative bacteria but requires supplementation with 0.2% yeast extract to support the growth of gram-positive bacteria. Experiments are also presented that show an unexpected but major influence of P. mirabilis towards the ability to measure bacterial growth in generally accepted multiwell assays using absorbance readings, predicted to have a basis in the release of volatile organic compound(s) from P. mirabilis during growth in Composite SHU medium. This study represents an essential methodological validation of a more chemically defined type of synthetic urine that can be applied to study mechanisms of bacteriuria and we conclude will offer a useful in vitro model to investigate the

  19. Bactericidal Efficacy of Hydrogen Peroxide-Based Disinfectants Against Gram-Positive and Gram-Negative Bacteria on Stainless Steel Surfaces.

    Science.gov (United States)

    Ríos-Castillo, Abel G; González-Rivas, Fabián; Rodríguez-Jerez, José J

    2017-10-01

    In order to develop disinfectant formulations that leverage the effectiveness of hydrogen peroxide (H 2 O 2 ), this study evaluated the bactericidal efficacy of hydrogen peroxide-based disinfectants against Gram-positive and Gram-negative bacteria on stainless steel surfaces. Low concentration of hydrogen peroxide as 0.5% with a cationic polymer, ethoxylated fatty alcohol, and ethyl alcohol had bactericidal efficacy (reductions ≥ 4 log 10 CFU/mL) against Escherichia coli, Staphylococcus aureus, Enterococcus hirae, and Pseudomonas aeruginosa. Hydrogen peroxide-based disinfectants were more effective against E. hirae and P. aeruginosa than to S. aureus. However, the efficacy of hydrogen peroxide against catalase positive bacteria such as S. aureus was increased when this compound was formulated with low concentrations of benzalkonium chloride or ethyl alcohol, lactic acid, sodium benzoate, cationic polymer, and salicylic acid. This study demonstrates that the use of hydrogen peroxide with other antimicrobial products, in adequate concentrations, had bactericidal efficacy in Gram-positive and Gram-negative bacteria on stainless steel surfaces, enabling to reduce the effective concentration of hydrogen peroxide. In the same way, the use of hydrogen peroxide-based disinfectants could reduce the concentrations of traditional disinfectants as quaternary ammonium compounds and therefore a reduction of their chemical residues in the environment after being used. The study of the bactericidal properties of environmentally nontoxic disinfectants such as hydrogen peroxide, sole or in formulations with other disinfectants against Gram-positive and Gram-negative bacteria can enhance the efficacy of various commonly used disinfectant formulations with the hygiene benefits that it entails. Also, the use of hydrogen peroxide formulations can reduce the concentration levels of products that generate environmental residues. © 2017 Institute of Food Technologists®.

  20. Prevalence of Gram-negative bacteria in ventilator-associated pneumonia in neonatal intensive care units: a systematic review and meta-analysis protocol.

    Science.gov (United States)

    Erfani, Yousef; Rasti, Arezoo; Janani, Leila

    2016-10-11

    Ventilator-associated pneumonia (VAP) is a common and potentially lethal problem among mechanically ventilated neonates in neonatal intensive care units (NICUs). The main pathogenic bacteria of VAP in NICUs are Gram-negative pathogens, which show a general decline in sensitivities to commonly used antibiotics, but their true prevalence is not known. We aim to provide a systematic review of studies measuring the prevalence of Gram-negative bacteria in VAP in NICUs. We will search PubMed, SCOPUS, EMBASE and the ISI Web of Science, as well as the Google Scholar search engine with no restriction on language. Full copies of articles will be identified by a defined search strategy and will be considered for inclusion against predefined criteria. Study selection and data extraction will be performed by 2 independent reviewers. Statistical analysis will include the identification of data sources and documentation of estimates, as well as the application of the random-effects and fixed-effects meta-analysis models. This will allow us to aggregate prevalence estimates and account for between-study variability in calculating the overall pooled estimates and 95% CI for the prevalence of Gram-negative bacteria in VAP in NICUs. Heterogeneity will be evaluated using the I 2 and χ 2 statistical tests to determine the extent of variation in effect estimates due to heterogeneity rather than chance. Publication bias and data synthesis will be assessed by funnel plots and Begg's and Egger's tests using STATA software V.13. This systematic review protocol was prepared according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses Protocols (PRISMA-P) 2015 Statement. No ethical issues are predicted. These findings will be published in a peer-reviewed journal and presented at national and international conferences. CRD42016036048. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  1. Physico-Chemical-Managed Killing of Penicillin-Resistant Static and Growing Gram-Positive and Gram-Negative Vegetative Bacteria

    Science.gov (United States)

    Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor); Farris, III, Alex F. (Inventor)

    2012-01-01

    Systems and methods for the use of compounds from the Hofmeister series coupled with specific pH and temperature to provide rapid physico-chemical-managed killing of penicillin-resistant static and growing Gram-positive and Gram-negative vegetative bacteria. The systems and methods represent the more general physico-chemical enhancement of susceptibility for a wide range of pathological macromolecular targets to clinical management by establishing the reactivity of those targets to topically applied drugs or anti-toxins.

  2. Discrepancy in MALDI-TOF MS identification of uncommon Gram-negative bacteria from lower respiratory secretions in patients with cystic fibrosis

    Directory of Open Access Journals (Sweden)

    AbdulWahab A

    2015-04-01

    Full Text Available Atqah AbdulWahab,1,2 Saad J Taj-Aldeen,3 Emad Bashir Ibrahim,3 Eman Talaq,4 Marawan Abu-Madi,4 Rashmi Fotedar5 1Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar; 2Department of Pediatrics, Weill Cornell Medical College, Doha, Qatar; 3Microbiology Division, Department of Laboratory Medicine and Pathology, Hamad Medical Corporation, Doha, Qatar; 4Department of Health Sciences, College of Arts and Sciences, Qatar University, Doha, Qatar; 5Biotechnology Center, Ministry of Environment, Doha, Qatar Introduction: Early identification of microbial organisms from respiratory secretions of patients with cystic fibrosis (CF is important to guide therapeutic decisions. The objective was to compare the accuracy of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS relative to the conventional phenotypic method in identifying common bacterial isolates, including nonfermenting Gram-negative bacteria, in a cohort of patients with CF. Methods: A total of 123 isolates from 50 patients with CF representing 14 bacterial species from respiratory specimens were identified using MALDI-TOF MS in parallel with conventional phenotypic methods. Discrepancies were confirmed by 16S ribosomal RNA (rRNA gene sequencing in five Gram-negative isolates. Results: The MALDI-TOF MS managed to identify 122/123 (99.2% bacterial isolates to the genus level and 118/123 (95.9% were identified to the species level. The MALDI-TOF MS results were 100% consistent to the species level with conventional phenotypic identification for isolates of Staphylococcus aureus, Pseudomonas aeruginosa, Haemophilus influenzae, Streptococcus pyogenes, Achromobacter xylosoxidans, Stenotrophomonas maltophilia, and other uncommon organisms such as Chryseobacterium gleum and Enterobacter cloacae. The 5/123 (4.6% isolates misidentified were all Gram-negative bacteria. The isolation of E. cloacae and Haemophilus paraphrohaemolyticus may extend the

  3. Adaptation of the Yeast URA3 Selection System to Gram-Negative Bacteria and Generation of a ΔbetCDE Pseudomonas putida Strain

    OpenAIRE

    Galvão, Teca Calcagno; de Lorenzo, Víctor

    2005-01-01

    A general procedure for efficient generation of gene knockouts in gram-negative bacteria by the adaptation of the Saccharomyces cerevisiae URA3 selection system is described. A Pseudomonas putida strain lacking the URA3 homolog pyrF (encoding orotidine-5′-phosphate decarboxylase) was constructed, allowing the use of a plasmid-borne copy of the gene as the target of selection. The delivery vector pTEC contains the pyrF gene and promoter, a conditional origin of replication (oriR6K), an origin ...

  4. The Bactericidal Activity of the C-type Lectin RegIIIβ against Gram-negative Bacteria involves Binding to Lipid A*

    Science.gov (United States)

    Miki, Tsuyoshi; Holst, Otto; Hardt, Wolf-Dietrich

    2012-01-01

    RegIIIβ is a member of the C-type lectin family called RegIII. It is known to bind peptidoglycan, and its bactericidal activity shapes the interactions with commensal and pathogenic gut bacteria. However, little is known about its carbohydrate recognition specificity and the bactericidal mechanism, particularly against Gram-negative bacteria. Here, we show that RegIIIβ can bind directly to LPS by recognizing the carbohydrate moiety of lipid A via a novel motif that is indispensable for its bactericidal activity. This bactericidal activity of RegIIIβ could be inhibited by preincubation with LPS, lipid A, or gentiobiose. The latter is a disaccharide composed of two units of β-(1→6)-linked d-glucose and resembles the carbohydrate moiety of lipid A. Therefore, this structural element may form a key target site recognized by RegIIIβ. Using point-mutated RegIIIβ proteins, we found that amino acid residues in two structural motifs termed “loop 1” and “loop 2,” are important for peptidoglycan and lipid A binding (Arg-135, Asp-142) and for the bactericidal activity (Glu-134, Asn-136, Asp-142). Thus, the ERN motif and residue Asp-142 in the loop 2 are of critical importance for RegIIIβ function. This provides novel insights into the carbohydrate recognition specificity of RegIIIβ and explains its bactericidal activity against Gram-negative bacteria. PMID:22896700

  5. Functional synergy of α-helical antimicrobial peptides and traditional antibiotics against Gram-negative and Gram-positive bacteria in vitro and in vivo.

    Science.gov (United States)

    Feng, Q; Huang, Y; Chen, M; Li, G; Chen, Y

    2015-01-01

    In this study, the antimicrobial activities based on the synergistic effects of traditional antibiotics (imipenem, cefepime, levofloxacin hydrochloride and vancomycin) and antimicrobial peptides (AMPs; PL-5, PL-31, PL-32, PL-18, PL-29 and PL-26), alone or in combination, against three Gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae and Staphylococcus epidermidis) and three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) were investigated. In addition, the antimicrobial activity that was based on the synergistic effects of levofloxacin hydrochloride and PL-5 against Staphylococcus aureus in vivo was explored in a mouse infection model. Traditional antibiotics and AMPs showed significant synergistic effects on the antibacterial activities against the different Gram-positive and Gram-negative bacteria in vitro. A strong synergistic effect in the PL-5 and levofloxacin hydrochloride combination against Staphylococcus aureus was observed in the mouse infection model in vivo. The mechanism of synergistic action was due to the different targets of AMPs and traditional antibiotics. The combination of AMPs and traditional antibiotics can dramatically enhance antimicrobial activity and may help prevent or delay the emergence of antibiotic resistance. Thus, this combination therapy could be a promising approach to treat bacterial infections, particularly mixed infections and multi-antibiotic-resistant infections, in the clinics.

  6. Minimum inhibitory concentrations of herbal essential oils and monolaurin for gram-positive and gram-negative bacteria.

    Science.gov (United States)

    Preuss, Harry G; Echard, Bobby; Enig, Mary; Brook, Itzhak; Elliott, Thomas B

    2005-04-01

    New, safe antimicrobial agents are needed to prevent and overcome severe bacterial, viral, and fungal infections. Based on our previous experience and that of others, we postulated that herbal essential oils, such as those of origanum, and monolaurin offer such possibilities. We examined in vitro the cidal and/or static effects of oil of origanum, several other essential oils, and monolaurin on Staphylococcus aureus, Bacillus anthracis Sterne, Escherichia coli, Klebsiella pneumoniae, Helicobacter pylori, and Mycobacterium terrae. Origanum proved cidal to all tested organisms with the exception of B. anthracis Sterne in which it was static. Monolaurin was cidal to S. aureus and M. terrae but not to E. coli and K. pneumoniae. Unlike the other two gram-negative organisms, H. pylori were extremely sensitive to monolaurin. Similar to origanum, monolaurin was static to B. anthracis Sterne. Because of their longstanding safety record, origanum and/or monolaurin, alone or combined with antibiotics, might prove useful in the prevention and treatment of severe bacterial infections, especially those that are difficult to treat and/or are antibiotic resistant.

  7. Biocompatible Fe3O4 Increases the Efficacy of Amoxicillin Delivery against Gram-Positive and Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Alexandru Mihai Grumezescu

    2014-04-01

    Full Text Available This paper reports the synthesis and characterization of amoxicillin- functionalized magnetite nanostructures (Fe3O4@AMO, revealing and discussing several biomedical applications of these nanomaterials. Our results proved that 10 nm Fe3O4@AMO nanoparticles does not alter the normal cell cycle progression of cultured diploid cells, and an in vivo murine model confirms that the nanostructures disperse through the host body and tend to localize in particular sites and organs. The nanoparticles were found clustered especially in the lungs, kidneys and spleen, next to the blood vessels at this level, while being totally absent in the brain and liver, suggesting that they are circulated through the blood flow and have low toxicity. Fe3O4@AMO has the ability to be easily circulated through the body and optimizations may be done so these nanostructures cluster to a specific target region. Functionalized magnetite nanostructures proved a great antimicrobial effect, being active against both the Gram positive pathogen S. aureus and the Gram negative pathogen E. coli. The fabricated nanostructures significantly reduced the minimum inhibitory concentration (MIC of the active drug. This result has a great practical relevance, since the functionalized nanostructures may be used for decreasing the therapeutic doses which usually manifest great severe side effects, when administrated in high doses. Fe3O4@AMO represents also a suitable approach for the development of new alternative strategies for improving the activity of therapeutic agents by targeted delivery and controlled release.

  8. Biocompatible Fe3O4 increases the efficacy of amoxicillin delivery against Gram-positive and Gram-negative bacteria.

    Science.gov (United States)

    Grumezescu, Alexandru Mihai; Gestal, Monica Cartelle; Holban, Alina Maria; Grumezescu, Valentina; Vasile, Bogdan Stefan; Mogoantă, Laurențiu; Iordache, Florin; Bleotu, Coralia; Mogoșanu, George Dan

    2014-04-22

    This paper reports the synthesis and characterization of amoxicillin- functionalized magnetite nanostructures (Fe3O4@AMO), revealing and discussing several biomedical applications of these nanomaterials. Our results proved that 10 nm Fe3O4@AMO nanoparticles does not alter the normal cell cycle progression of cultured diploid cells, and an in vivo murine model confirms that the nanostructures disperse through the host body and tend to localize in particular sites and organs. The nanoparticles were found clustered especially in the lungs, kidneys and spleen, next to the blood vessels at this level, while being totally absent in the brain and liver, suggesting that they are circulated through the blood flow and have low toxicity. Fe3O4@AMO has the ability to be easily circulated through the body and optimizations may be done so these nanostructures cluster to a specific target region. Functionalized magnetite nanostructures proved a great antimicrobial effect, being active against both the Gram positive pathogen S. aureus and the Gram negative pathogen E. coli. The fabricated nanostructures significantly reduced the minimum inhibitory concentration (MIC) of the active drug. This result has a great practical relevance, since the functionalized nanostructures may be used for decreasing the therapeutic doses which usually manifest great severe side effects, when administrated in high doses. Fe3O4@AMO represents also a suitable approach for the development of new alternative strategies for improving the activity of therapeutic agents by targeted delivery and controlled release.

  9. A large family of antivirulence regulators modulates the effects of transcriptional activators in Gram-negative pathogenic bacteria.

    Directory of Open Access Journals (Sweden)

    Araceli E Santiago

    2014-05-01

    Full Text Available We have reported that transcription of a hypothetical small open reading frame (orf60 in enteroaggregative E. coli (EAEC strain 042 is impaired after mutation of aggR, which encodes a global virulence activator. We have also reported that the cryptic orf60 locus was linked to protection against EAEC diarrhea in two epidemiologic studies. Here, we report that the orf60 product acts as a negative regulator of aggR itself. The orf60 protein product lacks homology to known repressors, but displays 44-100% similarity to at least fifty previously undescribed small (<10 kDa hypothetical proteins found in many gram negative pathogen genomes. Expression of orf60 homologs from enterotoxigenic E. coli (ETEC repressed the expression of the AraC-transcriptional ETEC regulator CfaD/Rns and its regulon in ETEC strain H10407. Complementation in trans of EAEC 042orf60 by orf60 homologs from ETEC and the mouse pathogen Citrobacter rodentium resulted in dramatic suppression of aggR. A C. rodentium orf60 homolog mutant showed increased levels of activator RegA and increased colonization of the adult mouse. We propose the name Aar (AggR-activated regulator for the clinically and epidemiologically important orf60 product in EAEC, and postulate the existence of a large family of homologs among pathogenic Enterobacteriaceae and Pasteurellaceae. We propose the name ANR (AraC Negative Regulators for this family.

  10. From Farms to Markets: Gram-Negative Bacteria Resistant to Third-Generation Cephalosporins in Fruits and Vegetables in a Region of North Africa

    Directory of Open Access Journals (Sweden)

    Ferielle Mesbah Zekar

    2017-08-01

    Full Text Available The role of food in human exposure to antimicrobial-resistant bacteria is a growing food safety issue. The contribution of fruits and vegetables eaten raw to this exposure is still unclear. The evaluation of contamination levels of fruits, vegetables and the agricultural environment by third-generation cephalosporin (3GC-resistant Gram-negative bacteria was performed by analyzing 491 samples of fruits and vegetables collected from 5 markets and 7 farms in Bejaia area, north-eastern Mediterranean coast of Algeria. Ninety soil samples and 45 irrigation water samples were also sampled in farms in order to assess them as potential inoculum sources. All samples were investigated at the same time on ceftazidime-containing selective media for 3GC-resistant Gram-negative bacteria detection and on Hektoen media, for Salmonella spp. presence. The bacteria isolated (n = 30 from fruits and vegetables, soil and irrigation water collected in the farms were almost all non-fermenting bacterial species (Stenotrophomonas, Acinetobacter, Pseudomonas, Ochrobactrum except one strain of Enterobacter cloacae and two strains of Citrobacter murliniae, isolated on one cucumber and two tomato samples in the same farm. Greater diversity in bacterial species and antimicrobial resistance profiles was observed at markets: Enterobacteriaceae (n = 41 were as strongly represented as non-fermenting bacteria (n = 37. Among Enterobacteriaceae, E. cloacae (n = 21, and Klebsiella pneumoniae (n = 13 were the most common isolates. Most of the K. pneumoniae isolates were extended-spectrum beta-lactamase (ESBL producers (n = 11. No Salmonella spp. was recovered in any sample. This study showed that fruits and vegetables including those which may be eaten up raw constitute a reservoir of 3GC-resistant Gram-negative bacteria and multi-drug resistant-bacteria in general that can be transferred to humans through food. The general public should be informed of this hazard for health in order

  11. Infection with multidrug-resistant gram-negative bacteria in a pediatric oncology intensive care unit: risk factors and outcomes.

    Science.gov (United States)

    Costa, Patrícia de Oliveira; Atta, Elias Hallack; Silva, André Ricardo Araújo da

    2015-01-01

    This study aimed at evaluating the predictors and outcomes associated with multidrug-resistant gram-negative bacterial (MDR-GNB) infections in an oncology pediatric intensive care unit (PICU). Data were collected relating to all episodes of GNB infection that occurred in a PICU between January of 2009 and December of 2012. GNB infections were divided into two groups for comparison: (1) infections attributed to MDR-GNB and (2) infections attributed to non-MDR-GNB. Variables of interest included age, gender, presence of solid tumor or hematologic disease, cancer status, central venous catheter use, previous Pseudomonas aeruginosa infection, healthcare-associated infection, neutropenia in the preceding 7 days, duration of neutropenia, length of hospital stay before ICU admission, length of ICU stay, and the use of any of the following in the previous 30 days: antimicrobial agents, corticosteroids, chemotherapy, or radiation therapy. Other variables included initial appropriate antimicrobial treatment, definitive inadequate antimicrobial treatment, duration of appropriate antibiotic use, time to initiate adequate antibiotic therapy, and the 7- and 30-day mortality. Multivariate logistic regression analyses showed significant relationships between MDR-GNB and hematologic diseases (odds ratio [OR] 5.262; 95% confidence interval [95% CI] 1.282-21.594; p=0.021) and healthcare-associated infection (OR 18.360; 95% CI 1.778-189.560; p=0.015). There were significant differences between MDR-GNB and non-MDR-GNB patients for the following variables: inadequate initial empirical antibiotic therapy, time to initiate adequate antibiotic treatment, and inappropriate antibiotic therapy. Hematologic malignancy and healthcare-associated infection were significantly associated with MDR-GNB infection in this sample of pediatric oncology patients. Copyright © 2015 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  12. Risk factors for hospital-acquired pneumonia caused by carbapenem-resistant Gram-negative bacteria in critically ill patients: a multicenter study in Korea.

    Science.gov (United States)

    Kim, Tark; Chong, Yong Pil; Park, Seong Yeon; Jeon, Min-Hyok; Choo, Eun Joo; Chung, Jin-Won; Lee, Hyun Kyung; Moon, Chisook; Kim, Dong-Min; Peck, Kyong Ran; Kim, Yang Soo

    2014-04-01

    We performed a case-control study to identify risk factors of carbapenem-resistant Gram-negative bacteria (CRGNB) as an increasing cause of hospital-acquired pneumonia (HAP). The study included critically ill adult patients with HAP whose microbial etiology was identified at eight tertiary centers in Korea between June 2008 and December 2009. Eighty two patients with 86 isolates of CRGNB (62 Acinetobacter baumannii, 14 Pseudomonas aeruginosa, and 10 Stenotrophomonas maltophilia) were included in the case group, and 122 patients with carbapenem-susceptible Gram-negative bacteria were included in the control group. Diabetes mellitus (adjusted odds ratio [aOR] 2.82, 95% confidence interval [95% CI] 1.25-6.38), radiologic score ≥5 (aOR 4.56, 95% CI 2.36-8.81), prior fluoroquinolone (aOR 2.39. 95% CI = 1.07-5.35), or carbapenem usage (aOR 2.82, 95% CI 1.75-17.83) were found to be independent risk factors. Fluoroquinolone and carbapenem should be cautiously used to avoid HAP caused by CRGNB. © 2014.

  13. Specific Clinical Profile and Risk Factors for Mortality in General Surgery Patients with Infections by Multi-Drug-Resistant Gram-Negative Bacteria.

    Science.gov (United States)

    Rubio-Perez, Ines; Martin-Perez, Elena; Domingo-García, Diego; Garcia-Olmo, Damian

    2017-07-01

    The incidence of gram-negative multi-drug-resistant (MDR) infections is increasing worldwide. This study sought to determine the incidence, clinical profiles, risk factors, and mortality of these infections in general surgery patients. All general surgery patients with a clinical infection by gram-negative MDR bacteria were studied prospectively for a period of five years (2007-2011). Clinical, surgical, and microbiologic parameters were recorded, with a focus on the identification of risk factors for MDR infection and mortality. Incidence of MDR infections increased (5.6% to 15.2%) during the study period; 106 patients were included, 69.8% presented nosocomial infections. Mean age was 65 ± 15 years, 61% male. Extended-spectrum β-lactamases (ESBL) Escherichia coli was the most frequent MDR bacteria. Surgical site infections and abscesses were the most common culture locations. The patients presented multiple pre-admission risk factors and invasive measures during hospitalization. Mortality was 15%, and related to older age (odds ratio [OR] 1.07), malnutrition (OR 13.5), chronic digestive conditions (OR 4.7), chronic obstructive pulmonary disease (OR 3.9), and surgical re-intervention (OR 9.2). Multi-drug resistant infections in the surgical population are increasing. The most common clinical profile is a 65-year-old male, with previous comorbidities, who has undergone a surgical intervention, intensive care unit (ICU) admission, and invasive procedures and who has acquired the MDR infection in the nosocomial setting.

  14. [Antimicrobial susceptibility patterns of Gram-negative bacteria isolated in urinary tract infections in Venezuela: Results of the SMART study 2009-2012].

    Science.gov (United States)

    Guevara, Napoleón; Guzmán, Manuel; Merentes, Altagracia; Rizzi, Adele; Papaptzikos, Juana; Rivero, Narlesky; Oranges, Carmela; Vlllarroel, Héctor; Limas, Yoxsivell

    2015-12-01

    Antimicrobial resistance of pathogens causing urinary tract infection (UTI) is a growing problem, which complicates their effective treatment. Surveillance is needed to guide appropriate empiric therapy. to describe the susceptibility patterns of Gram-negative bacteria isolated of patients with UTI to twelve antibiotics as part of the Study for Monitoring Antimicrobial Resistance Trends in Venezuela. Between 2009-2012 a total of 472 Gram-negative bacteria were isolated from hospitalized patients with UTI. The isolates were sent to Central Laboratory (Central Laboratory of International Health Management Associates) to confirm their identification, and to make susceptibility testing as recommended by the Clinical and Laboratory Standards Institute. Enterobacteriacea comprised 96.6% of the total, where Escherichia coli (76.9%) and Klebsiella pneumoniae (10.6%) were the most frequent. Extended-spectrum β-lactamases (ESBL) was detected in 21.6% of isolates. Top antimicrobial activity were ertapenem, imipenem, and amikacin (> 90.0%), slightly lower for amikacin (85.1%) in ESBL-producing strains. Resistance rates to fluoroquinolones and ampicillin/sulbactam were high (40 y 64%, respectively). These data suggest a necessary revision of the therapeutic regimens for the empirical treatment of UTI in Venezuela.

  15. Comparison of killing of gram-negative and gram-positive bacteria by pure singlet oxygen. [Salmonella typhimurium; Escherichia coli; Sarcina lutea; Staphylococcus aureus; Streptococcus lactis; Streptococcus faecalis

    Energy Technology Data Exchange (ETDEWEB)

    Dahl, T.A.; Midden, W.R. (Bowling Green State Univ., OH (USA)); Hartman, P.E. (Johns Hopkins Univ., Baltimore, MD (USA))

    1989-04-01

    Gram-negative and gram-positive bacteria were found to display different sensitivities to pure singlet oxygen generated outside of cells. Killing curves for Salmonella typhimurium and Escherichia coli strains were indicative of multihit killing, whereas curves for Sarcina lutea, Staphylococcus aureus, Streptococcus lactis, and Streptococcus faecalis exhibited single-hit kinetics. The S. typhimurium deep rough strain TA1975, which lacks nearly all of the cell wall lipopolysaccharide coat and manifests concomitant enhancement of penetration by some exogenous substances, responded to singlet oxygen with initially faster inactivation than did the S. typhimurium wild-type strain, although the maximum rates of killing appeared to be quite similar. The structure of the cell wall thus plays an important role in susceptibility to singlet oxygen. The outer membrane-lipopolysaccharide portion of the gram-negative cell wall initially protects the bacteria from extracellular singlet oxygen, although it may also serve as a source for secondary reaction products which accentuate the rates of cell killing. S. typhimurium and E. coli strains lacking the cellular antioxidant, glutathione, showed no difference from strains containing glutathione in response to the toxic effects of singlet oxygen. Strains of Sarcina lutea and Staphylococcus aureus that contained carotenoids, however, were far more resistant to singlet oxygen lethality than were both carotenoidless mutants of the same species and other gram-positive species lacking high levels of protective carotenoids.

  16. Identification of UBact, a ubiquitin-like protein, along with other homologous components of a conjugation system and the proteasome in different gram-negative bacteria.

    Science.gov (United States)

    Lehmann, Gilad; Udasin, Ronald G; Livneh, Ido; Ciechanover, Aaron

    2017-02-12

    Systems analogous to the eukaryotic ubiquitin-proteasome system have been previously identified in Archaea, and Actinobacteria (gram-positive), but not in gram-negative bacteria. Here, we report the bioinformatic identification of a novel prokaryotic ubiquitin-like protein, which we name UBact. The phyletic distribution of UBact covers at least five gram-negative bacterial phyla, including Nitrospirae, Armatimonadetes, Verrucomicroba, Nitrospinae, and Planctomycetes. Additionally, it was identified in seven candidate (uncultured) phyla and one Archaeon. UBact might have been overlooked because only few species in the phyla where it is found have been sequenced. In most of the species where we identified UBact, its neighbors in the genome code for proteins homologous to those involved in conjugation and/or degradation of Pup and Pup-tagged substrates. Among them are PafA-, Dop-, Mpa- and proteasome-homologous proteins. This gene association as well as UBact's size and conserved C-terminal G[E/Q] motif, strongly suggest that UBact is used as a conjugatable tag for degradation. With regard to its C-terminus, UBact differs from ubiquitin and most ubiquitin-like proteins (including the mycobacterial Pup) in that it lacks the characteristic C-terminal di-glycine motif, and it usually ends with the sequence R[T/S]G[E/Q]. The phyla that contain UBact are thought to have diverged over 3000 million years ago, indicating that either this ubiquitin-like conjugation system evolved early in evolution or that its occurrence in distant gram-negative phyla is due to multiple instances of horizontal gene transfer. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Antibacterial agents and heavy metal resistance in Gram-negative bacteria isolated from seawater, shrimp and sediment in Iskenderun Bay, Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Matyar, Fatih [Cukurova University, Faculty of Education, Department of Science and Technology Education, 01330 Balcali, Adana (Turkey)], E-mail: fmatyar@cu.edu.tr; Kaya, Aysenur; Dincer, Sadik [Cukurova University, Faculty of Science and Letters, Department of Biology, 01330 Balcali, Adana (Turkey)

    2008-12-15

    The aim of the present study was to determine the level of antibiotic resistance patterns and distribution of heavy metal resistance of bacterial isolates from seawater, sediment and shrimps, and to determine if there is a relationship between antibiotic and heavy metal resistance. We undertook studies in 2007 in the industrially polluted Iskenderun Bay, on the south coast of Turkey. The resistance of 236 Gram-negative bacterial isolates (49 from seawater, 90 from sediment and 97 from shrimp) to 16 different antibiotics, and to 5 heavy metals, was investigated by agar diffusion and agar dilution methods, respectively. A total of 31 species of bacteria were isolated: the most common strains isolated from all samples were Escherichia coli (11.4%), Aeromonas hydrophila (9.7%) and Stenotrophomonas maltophilia (9.3%). There was a high incidence of resistance to ampicillin (93.2%), streptomycin (90.2%) and cefazolin (81.3%), and a low incidence of resistance to imipenem (16.5%), meropenem (13.9%) and cefepime (8.0%). Some 56.8% of all bacteria isolated from seawater, sediment and shrimp were resistant to 7 or more antibiotics. Most isolates showed tolerance to different concentrations of heavy metals, and minimal inhibition concentrations ranged from 12.5 {mu}g/ml to > 3200 {mu}g/ml. The bacteria from seawater, sediment and shrimp showed high resistance to cadmium of 69.4%, 88.9%, and 81.1% respectively, and low resistance to manganese of 2%, 6.7% and 11.3% respectively. The seawater and sediment isolates which were metal resistant also showed a high resistance to three antibiotics: streptomycin, ampicillin and trimethoprim-sulphamethoxazole. In contrast, the shrimp isolates which were metal resistant were resistant to four antibiotics: cefazolin, nitrofurantoin, cefuroxime and ampicillin. Our results show that Iskenderun Bay has a significant proportion of antibiotic and heavy metal resistant Gram-negative bacteria, and these bacteria constitute a potential risk for

  18. Antibacterial agents and heavy metal resistance in Gram-negative bacteria isolated from seawater, shrimp and sediment in Iskenderun Bay, Turkey

    International Nuclear Information System (INIS)

    Matyar, Fatih; Kaya, Aysenur; Dincer, Sadik

    2008-01-01

    The aim of the present study was to determine the level of antibiotic resistance patterns and distribution of heavy metal resistance of bacterial isolates from seawater, sediment and shrimps, and to determine if there is a relationship between antibiotic and heavy metal resistance. We undertook studies in 2007 in the industrially polluted Iskenderun Bay, on the south coast of Turkey. The resistance of 236 Gram-negative bacterial isolates (49 from seawater, 90 from sediment and 97 from shrimp) to 16 different antibiotics, and to 5 heavy metals, was investigated by agar diffusion and agar dilution methods, respectively. A total of 31 species of bacteria were isolated: the most common strains isolated from all samples were Escherichia coli (11.4%), Aeromonas hydrophila (9.7%) and Stenotrophomonas maltophilia (9.3%). There was a high incidence of resistance to ampicillin (93.2%), streptomycin (90.2%) and cefazolin (81.3%), and a low incidence of resistance to imipenem (16.5%), meropenem (13.9%) and cefepime (8.0%). Some 56.8% of all bacteria isolated from seawater, sediment and shrimp were resistant to 7 or more antibiotics. Most isolates showed tolerance to different concentrations of heavy metals, and minimal inhibition concentrations ranged from 12.5 μg/ml to > 3200 μg/ml. The bacteria from seawater, sediment and shrimp showed high resistance to cadmium of 69.4%, 88.9%, and 81.1% respectively, and low resistance to manganese of 2%, 6.7% and 11.3% respectively. The seawater and sediment isolates which were metal resistant also showed a high resistance to three antibiotics: streptomycin, ampicillin and trimethoprim-sulphamethoxazole. In contrast, the shrimp isolates which were metal resistant were resistant to four antibiotics: cefazolin, nitrofurantoin, cefuroxime and ampicillin. Our results show that Iskenderun Bay has a significant proportion of antibiotic and heavy metal resistant Gram-negative bacteria, and these bacteria constitute a potential risk for public

  19. A 980nm driven photothermal ablation of virulent and antibiotic resistant Gram-positive and Gram-negative bacteria strains using Prussian blue nanoparticles.

    Science.gov (United States)

    Maaoui, Houcem; Jijie, Roxana; Pan, Guo-Hui; Drider, Djamel; Caly, Delphine; Bouckaert, Julie; Dumitrascu, Nicoleta; Chtourou, Radouane; Szunerits, Sabine; Boukherroub, Rabah

    2016-10-15

    A 980nm laser-driven antimicrobial photothermal therapy using poly(vinylpyrrolidone) -coated Prussian Blue nanoparticles (PVP/PB NPs) is demonstrated. This approach allows an efficient eradication of a virulent strain of Gram-negative Escherichia coli (E. coli) associated with urinary tract infection as well as for the ablation of antibiotic resistant pathogens such as methicillin resistant Staphylococcus aureus (MRSA) and extended spectrum β-lactamase (ESBL) E. coli. Interestingly the 980nm irradiation exhibits minimal effect on mammalian cells up to a PVP/PB NPs concentration of 50μgmL(-1), while at this concentration bacteria are completely eradicated. This feature is certainly very promising for the selective targeting of bacteria over mammalian cells. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Extracellular vesicles, especially derived from Gram-negative bacteria, in indoor dust induce neutrophilic pulmonary inflammation associated with both Th1 and Th17 cell responses.

    Science.gov (United States)

    Kim, Y-S; Choi, E-J; Lee, W-H; Choi, S-J; Roh, T-Y; Park, J; Jee, Y-K; Zhu, Z; Koh, Y-Y; Gho, Y S; Kim, Y-K

    2013-04-01

    Many bacterial components in indoor dust can evoke inflammatory pulmonary diseases. Bacteria secrete nanometre-sized vesicles into the extracellular milieu, but it remains to be determined whether bacteria-derived extracellular vesicles in indoor dust are pathophysiologically related to inflammatory pulmonary diseases. To evaluate whether extracellular vesicles (EV) in indoor air are related to the pathogenesis of pulmonary inflammation and/or asthma. Indoor dust was collected from a bed mattress in an apartment. EV were prepared by sequential ultrafiltration and ultracentrifugation. Innate and adaptive immune responses were evaluated after airway exposure of EV. Repeated intranasal application of indoor-dust-induced neutrophilic pulmonary inflammation accompanied by lung infiltration of both Th1 and Th17 cells. EV 50-200 nm in diameter were present (102.5 μg protein concentration/g dust) in indoor dust. These vesicles were internalized by airway epithelial cells and alveolar macrophages, and this process was blocked by treatment of polymyxin B (an antagonist of lipopolysaccharide, an outer-membrane component of Gram-negative bacteria). Intranasal application of 0.1 or 1 μg of these vesicles for 4 weeks elicited neutrophilic pulmonary inflammation. This phenotype was accompanied by lung infiltration of both Th1 and Th17 cells, which were reversed by treatment of polymyxin B. Serum dust EV-reactive IgG1 levels were significantly higher in atopic children with asthma than in atopic healthy children and those with rhinitis or dermatitis. Indoor dust EV, especially derived from Gram-negative bacteria, is a possible causative agent of neutrophilic airway diseases. © 2013 Blackwell Publishing Ltd.

  1. Dissemination of Trimethoprim-Sulfamethoxazole Drug Resistance Genes Associated with Class 1 and Class 2 Integrons Among Gram-Negative Bacteria from HIV Patients in South India.

    Science.gov (United States)

    Ramesh Kumar, Marimuthu Ragavan; Arunagirinathan, Narasingam; Srivani, Seetharaman; Dhanasezhian, Aridoss; Vijaykanth, Nallusamy; Manikandan, Natesan; Balakrishnan, Sethuramalingam; Vignesh, Ramachandran; Balakrishnan, Pachamuthu; Solomon, Suniti; Solomon, Sunil S

    2017-07-01

    The antibiotic, trimethoprim-sulfamethoxazole (TMP-SMX), is generally used for prophylaxis in HIV individuals to protect them from Pneumocystis jiroveci infection. Long-term use of TMP-SMX develops drug resistance among bacteria in HIV patients. The study was aimed to detect the TMP-SMX resistance genes among gram-negative bacteria from HIV patients. TMP-SMX-resistant isolates were detected by the Kirby-Bauer disc diffusion method. While TMP resistance genes such as dfrA1, dfrA5, dfrA7, and dfrA17 and SMX resistance genes such as sul1 and sul2 were detected by multiplex PCR, class 1 and class 2 integrons were detected by standard monoplex PCR. Of the 151 TMP-SMX-resistant bacterial isolates, 3 were positive for sul1 alone, 48 for sul2 alone, 11 for dfrA7 alone, 21 for sul1 and sul2, 1 for sul1 and dfrA7, 23 for sul2 and dfrA7, 2 for sul2 and dfrA5, 41 for sul1, sul2, and dfrA7, and 1 for sul2, dfrA5, and dfrA7. Of 60 TMP-SMX-resistant isolates positive for integrons, 44 had class 1 and 16 had class 2 integrons. It was found that the prevalence of sul genes (n = 202; p genes (n = 80; p resistant isolates also were positive for β-lactamase production. This type of study is reported for the first time from HIV patients in India. Therefore, this study indicates that dissemination of TMP-SMX resistance genes and class 1 and class 2 integrons along with β-lactamase production among gram-negative bacteria in HIV patients will certainly make their treatment to bacterial infections more complicated in clinical settings.

  2. An Eye to a Kill: Using Predatory Bacteria to Control Gram-Negative Pathogens Associated with Ocular Infections.

    Directory of Open Access Journals (Sweden)

    Robert M Q Shanks

    Full Text Available Ocular infections are a leading cause of vision loss. It has been previously suggested that predatory prokaryotes might be used as live antibiotics to control infections. In this study, Pseudomonas aeruginosa and Serratia marcescens ocular isolates were exposed to the predatory bacteria Micavibrio aeruginosavorus and Bdellovibrio bacteriovorus. All tested S. marcescens isolates were susceptible to predation by B. bacteriovorus strains 109J and HD100. Seven of the 10 P. aeruginosa isolates were susceptible to predation by B. bacteriovorus 109J with 80% being attacked by M. aeruginosavorus. All of the 19 tested isolates were found to be sensitive to at least one predator. To further investigate the effect of the predators on eukaryotic cells, human corneal-limbal epithelial (HCLE cells were exposed to high concentrations of the predators. Cytotoxicity assays demonstrated that predatory bacteria do not damage ocular surface cells in vitro whereas the P. aeruginosa used as a positive control was highly toxic. Furthermore, no increase in the production of the proinflammatory cytokines IL-8 and TNF-alpha was measured in HCLE cells after exposure to the predators. Finally, injection of high concentration of predatory bacteria into the hemocoel of Galleria mellonella, an established model system used to study microbial pathogenesis, did not result in any measurable negative effect to the host. Our results suggest that predatory bacteria could be considered in the near future as a safe topical bio-control agent to treat ocular infections.

  3. Effects of single amino acid substitution on the biophysical properties and biological activities of an amphipathic α-helical antibacterial peptide against Gram-negative bacteria.

    Science.gov (United States)

    Tan, Juanjuan; Huang, Jinfeng; Huang, Yibing; Chen, Yuxin

    2014-07-24

    An antimicrobial peptide, known as V13K, was utilized as the framework to study the effects of charge, hydrophobicity and helicity on the biophysical properties and biological activities of α-helical peptides. Six amino acids (Lys, Glu, Gly, Ser, Ala, and Leu) were individually used to substitute the original hydrophobic valine at the selected sixteenth location on the non-polar face of V13K. The results showed that the single amino acid substitutions changed the hydrophobicity of peptide analogs as monitored by RP-HPLC, but did not cause significant changes on peptide secondary structures both in a benign buffer and in a hydrophobic environment. The biological activities of the analogs exhibited a hydrophobicity-dependent behavior. The mechanism of peptide interaction with the outer membrane and cytoplasmic membrane of Gram-negative bacteria was investigated. We demonstrated that this single amino acid substitution method has valuable potential for the rational design of antimicrobial peptides with enhanced activities.

  4. Discovery and development of new antibacterial agents targeting Gram-negative bacteria in the era of pandrug resistance: is the future promising?

    Science.gov (United States)

    Page, Malcolm G P; Bush, Karen

    2014-10-01

    Multidrug-resistant Gram-negative bacteria continue to pose a threat, with many infections caused by these pathogens being virtually untreatable. A number of new antibacterial agents are in late stage clinical development to treat these infections. Drugs in known classes such as new quinolones, aminoglycosides, tetracyclines, and β-lactams have been designed to evade many of the known resistance mechanisms, whereas newer drug classes include novel β-lactamase inhibitors in combination with new or approved β-lactams, and a peptidomimetic that have entered full clinical development. The establishment of public-private partnerships and an increase in pharmaceutical interest in antibacterial R&D are encouraging signs for the future. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Geraldine Asencio

    2014-01-01

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

  6. Multidrug-Resistant Gram-Negative Bacteria Colonization of Healthy US Military Personnel in the US and Afghanistan

    Science.gov (United States)

    2013-02-05

    returning from leisure travel [2], the identification of novel resistance genes in patients seeking medical care in other countries [3], the finding of... travel , medical tourism , and military casualty movement is concerning [2-4]. For military personnel, one proposed source of MDR bacteria has been...were excluded if they had recent overseas travel (within 6 months), overseas deployment (within 6 months), or antibiotic use (within 30 days). The

  7. Radical scavenging and antibacterial activity of caffemides against gram positive, gram negative and clinical drug resistance bacteria.

    Science.gov (United States)

    Misra, Kaushik; Maity, Himadri Sekhar; Nag, Ahindra; Sonawane, Avinash

    2016-12-15

    A new series of caffemide were synthesized and their antioxidant and antibacterial activities were explored. Antioxidant and antibacterial activities were measured of different structures of caffemide containing different functional groups. Anti-oxidative caffemides 1b and 1g showed significantly higher activity against different bacteria with MIC values less than 50μg/ml. These anti-oxidative and antibacterial properties of caffemides might be helpful for the treatment of secondary infections and discovery of new antibiotics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Antibacterial and antibiotic resistance modulatory activities of leaves and bark extracts of Recinodindron heudelotii (Euphorbiaceae) against multidrug-resistant Gram-negative bacteria.

    Science.gov (United States)

    Fankam, Aimé Gabriel; Kuiate, Jules-Roger; Kuete, Victor

    2017-03-24

    Recinodindron heudelotii (Euphorbiaceae) is a plant used in Africa, particularly in Cameroon to treat various ailments including bacterial infections. In this study, we evaluated the extracts of the leaves (RHL) and bark (RHB) of R. heudelotii for their antibacterial and antibiotic resistance modulating activities against 29 Gram-negative bacteria, including multidrug-resistant (MDR) phenotypes. The broth micro-dilution assay was used to evaluate the antibacterial activity, and the antibiotic resistance modulating effects of the plant extracts. RHL displayed the most important spectrum of activity with minimal inhibitory concentrations (MICs) values ranging from 256 to 1024 μg/mL against 75.86% of the 29 tested bacteria strains while RHB was not active. RHL also showed killing effects with minimal bactericidal concentrations (MBCs) ranging from 256 to 1024 μg/mL. The activities of tetracycline and kanamycin associated with RHL were improved on 88.89% and 77.78% of the tested MDR bacteria, at MIC/2 at MIC/4 respectively, with 2 to 16-folds decreasing of MIC. This suggests the antibiotic resistance modulating effects of these antibiotics. The present study provides data indicating a possible use of the leaves extract of Recinodindron heudelotii alone or in association with common antibiotics in the fight against bacterial infections including those involving MDR bacteria.

  9. Efficient Photodynamic Therapy against Gram-Positive and Gram-Negative Bacteria Using THPTS, a Cationic Photosensitizer Excited by Infrared Wavelength

    Science.gov (United States)

    Schastak, Stanislaw; Ziganshyna, Svitlana; Gitter, Burkhard; Wiedemann, Peter; Claudepierre, Thomas

    2010-01-01

    The worldwide rise in the rates of antibiotic resistance of bacteria underlines the need for alternative antibacterial agents. A promising approach to kill antibiotic-resistant bacteria uses light in combination with a photosensitizer to induce a phototoxic reaction. Concentrations of 1, 10 and 100µM of tetrahydroporphyrin-tetratosylat (THPTS) and different incubation times (30, 90 and 180min) were used to measure photodynamic efficiency against two Gram-positive strains of S.aureus (MSSA and MRSA), and two Gram-negative strains of E.coli and P.aeruginosa. We found that phototoxicity of the drug is independent of the antibiotic resistance pattern when incubated in PBS for the investigated strains. Also, an incubation with 100µM THPTS followed by illumination, yielded a 6lg (≥99.999%) decrease in the viable numbers of all bacteria strains tested, indicating that the THPTS drug has a high degree of photodynamic inactivation. We then modulated incubation time, photosensitizer concentration and monitored the effect of serum on the THPTS activity. In doing so, we established the conditions to obtain the strongest bactericidal effect. Our results suggest that this new and highly pure synthetic compound should improve the efficiency of photodynamic therapy against multiresistant bacteria and has a significant potential for clinical applications in the treatment of nosocomial infections. PMID:20652031

  10. Charge effect on the photoinactivation of Gram-negative and Gram-positive bacteria by cationic meso-substituted porphyrins

    Directory of Open Access Journals (Sweden)

    Tomé Augusto C

    2009-04-01

    Full Text Available Abstract Background In recent times photodynamic antimicrobial therapy has been used to efficiently destroy Gram (+ and Gram (- bacteria using cationic porphyrins as photosensitizers. There is an increasing interest in this approach, namely in the search of photosensitizers with adequate structural features for an efficient photoinactivation process. In this study we propose to compare the efficiency of seven cationic porphyrins differing in meso-substituent groups, charge number and charge distribution, on the photodynamic inactivation of a Gram (+ bacterium (Enterococcus faecalis and of a Gram (- bacterium (Escherichia coli. The present study complements our previous work on the search for photosensitizers that might be considered good candidates for the photoinactivation of a large spectrum of environmental microorganisms. Results Bacterial suspension (107 CFU mL-1 treated with different photosensitizers concentrations (0.5, 1.0 and 5.0 μM were exposed to white light (40 W m-2 for a total light dose of 64.8 J cm-2. The most effective photosensitizers against both bacterial strains were the Tri-Py+-Me-PF and Tri-Py+-Me-CO2Me at 5.0 μM with a light fluence of 64.8 J cm-2, leading to > 7.0 log (> 99,999% of photoinactivation. The tetracationic porphyrin also proved to be a good photosensitizer against both bacterial strains. Both di-cationic and the monocationic porphyrins were the least effective ones. Conclusion The number of positive charges, the charge distribution in the porphyrins' structure and the meso-substituent groups seem to have different effects on the photoinactivation of both bacteria. As the Tri-Py+-Me-PF porphyrin provides the highest log reduction using lower light doses, this photosensitizer can efficiently photoinactivate a large spectrum of environmental bacteria. The complete inactivation of both bacterial strains with low light fluence (40 W m-2 means that the photodynamic approach can be applied to wastewater treatment

  11. [i]Legionella spp[/i]., amoebae and not-fermenting Gram negative bacteria in an Italian university hospital water system

    Directory of Open Access Journals (Sweden)

    Pasqualina Laganà

    2014-09-01

    Full Text Available [b]Introduction. [/b]In hospital and other health care facilities, contamination of water systems by potentially infectious microorganisms, such as bacteria, viruses and protozoa, is a source of nosocomial infections, which may originate fromcolonization of water pipes, cooling towers, spa pools, taps, showers and water supplies. [b]Objective. [/b]The study focuses on the occurrence of [i]Legionella spp.[/i], free-living amoebae and non-fermenting Gram-negative microorganisms in a University hospital water system located in the town of Messina (Sicily, Italy, which had never been examined previously. Materials and Methods. From January 2008 – March 2009, hot tap water samples were collected from 10 wards.[i] Legionella spp[/i]. recovered on selective culture medium were identified by microagglutination latex test; free-living amoebae were cultured using [i]Escherichia coli [/i]as a food source. Non-fermenting Gram negative microorganisms were identified by API 20 NE strips. [b]Results.[/b] [i]Legionella spp.[/i] were found in 33.33% of the samples. [i]L. pneumophila[/i] serogroup 1 was recovered from the Laboratory Diagnostic and Anaesthesia-Neurology Wards, with a peak of 3.5 × 10[sup]4[/sup] cfu/L in May 2008. [i]L. pneumophila[/i] serogroups 2–14 were found in the Othorhinolaryngology, Pathologic Anatomy, Paediatrics and Surgery Wards, and peaked (4 × 10[sup]4[/sup] cfu/L in April 2008. Pseudomonadaceae and Hyphomycetes were also detected. Legionella spp. were recovered from samples positive for non-pathogenic amoebae [i]Hartmannella spp[/i]. [b]Conclusion.[/b] This first study of a Messina hospital water system suggested potential health risks related to the detection of [i]Hartmannella spp[/i]., as reservoirs for[i] Legionella spp.[/i], and Pseudomonas aeruginosa, a Gram negative non-fermenting bacterium frequently causing nosocomial pneumonia. The urgent need for monitoring programmes and prevention measures to ensure hospital water

  12. Green synthesis of capped gold nanoparticles and their effect on Gram-positive and Gram-negative bacteria

    Science.gov (United States)

    Rao, Yashvant; Inwati, Gajendra K; Singh, Man

    2017-01-01

    Aim: We report synthesis of capped gold nanoparticles (C-AuNPs) of ≈20–30 nm by reducing HAuCl4 with flower and leaf extracts of Ocimum tenuiflorum, leaves of Azadirachta indica and Mentha spicata and peel of Citrus sinensis plants. Methods: Atomic force microscopy (AFM) and transmission electron microscopy (TEM) determined their size, shape and topographical structures. The C-AuNPs with UV-Vis spectrophotometer produced a maximum absorption within 530–535 nm wavelengths. Their Fourier transform IR stretching frequencies, from 450 to 4000 cm-1, have inferred HAuCl4 reduction to Au. Results: The 512 and 600 μgml-1 C-AuNP MICs were expressed on antimicrobial strains Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae, respectively. Conclusion: The chosen plant extracts have reduced the Au3+ to Au0 with simultaneous in situ capping with bacteria inhibiting activities. Green routes for C-AuNP synthesis could be an asset for several other biomedical and bioengineering applications. PMID:29134123

  13. Enumeration and identification of gram negative bacteria present in soil underlying urban waste-sites in southwestern Nigeria.

    Science.gov (United States)

    Achudume, A C; Olawale, J T

    2010-09-01

    Samples of soils underlying wastes were collected from four sites representing four demographic regions of a medium sized town in southwestern Nigeria. Standard methods and reference strains of isolated bacteria were employed for identification. Evaluation of the enzymatic and biochemical reactions showed that all isolated and identified microbes were non-fermenting heterotrophic (HTB). For example, Klebsiella pnemuniae may be involved in wound infections, particularly following bowel surgery. Similarly Pseudomonas aeruginosa can produce serious nosocomial infections if it gains access to the body through wounds or intravenous lines. From the 15 culure plates, 88 colonies with various characteristics were enumerated. They differed in aspect of viscosity and color. The bacterial species were identified by percent positive reactions while oxidative and sugar fermentation tests revealed various characteristics among the isolated strains. All of the isolates were negative for citrate utilization, gelatin liquefaction, nitrate reduction, methyl red and Voges Proskaur, motility and hydrogen sulphate production. The quantity of HTB present in an area serves as an index of the general sanitary conditions of that area. The presence of a large number of HTB, in an ecological area may be considered a liability as it can enhance the spread of diseases and on a larger scale may enable epidemics to arise. Therefore, there is need for control of waste sites by recovery and regular germicidal sanitation.

  14. LiF Reduces MICs of Antibiotics against Clinical Isolates of Gram-Positive and Gram-Negative Bacteria

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    H. C. Syed

    2012-01-01

    Full Text Available Antibiotic resistance is an ever-growing problem yet the development of new antibiotics has slowed to a trickle, giving rise to the use of combination therapy to eradicate infections. The purpose of this study was to evaluate the combined inhibitory effect of lithium fluoride (LiF and commonly used antimicrobials on the growth of the following bacteria: Enterococcus faecalis, Staphyloccoccus aureus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Serratia marcescens, and Streptococcus pneumoniae. The in vitro activities of ceftazidime, sulfamethoxazole-trimethoprim, streptomycin, erythromycin, amoxicillin, and ciprofloxacin, doxycycline, alone or combined with LiF were performed by microdilution method. MICs were determined visually following 18–20 h of incubation at 37°C. We observed reduced MICs of antibiotics associated with LiF ranging from two-fold to sixteen-fold. The strongest decreases of MICs observed were for streptomycin and erythromycin associated with LiF against Acinetobacter baumannii and Streptococcus pneumoniae. An eight-fold reduction was recorded for streptomycin against S. pneumoniae whereas an eight-fold and a sixteen-fold reduction were obtained for erythromycin against A. baumannii and S. pneumoniae. This suggests that LiF exhibits a synergistic effect with a wide range of antibiotics and is indicative of its potential as an adjuvant in antibiotic therapy.

  15. An overview of antimicrobial susceptibility patterns for gram-negative bacteria from the National Antimicrobial Resistance Surveillance Thailand (NARST) program from 2000 to 2005.

    Science.gov (United States)

    Apisarnthanarak, Anucha; Buppunharun, Wanchai; Tiengrim, Surapee; Sawanpanyalert, Pathom; Aswapokee, Nalinee

    2009-08-01

    The National Antimicrobial Resistance Surveillance Thailand (NARST) has been initiated since 1998 to strengthen the surveillance program for antimicrobial-resistant pathogens as well as to standardize the laboratory practices in Thailand. This collaborative network was funded by the World Health Organization, and involved 33 hospitals throughout Thailand at the first phase. Nevertheless, no prior effort has been made to share the antimicrobial resistance data in the national level. In this overview, the authors provide an update on the status of antimicrobial resistance from 2000 to 2005 among important Gram-negative pathogens as well as the implication of these findings. The most striking finding appears to be the emergence of pandrug-resistant (PDR) Acinetobacter baumannii. Carbapenem-resistant A. baumannii has been dramatically increasing from 2.1% in 2000 to 46.7% in 2005. There is a trend towards the increasing incidence rates of ESBL-producing Escherichia coli from 2000 to 2005, but the incidence rates of ESBL-producing Klebseilla pneumoniae remain constant during the same period. The susceptibility of Burkholderia pseudomallei to various antibiotics, particularly ceftazidime and carbapenems, approached 100%. In conclusions, to help strengthen the future surveillance system, NARST needs to develop the data collection tools that include some important patient characteristics and the information that can help distinguish colonizations and infections as well as community-acquired infections and hospital-acquired infections. In addition, an appropriate test for antimicrobial susceptibility including the minimal inhibitory concentration determination should be implemented and carried out for all important pathogens. The NARST data emphasized a need to strengthen the antimicrobial stewardship as well as the infection control measures at the hospital level to help reduce the transmission of antimicrobial-resistant Gram-negative bacteria in Thailand.

  16. Revisiting the gram-negative lipoprotein paradigm

    Science.gov (United States)

    The processing of lipoproteins (lpps) in Gram-negative bacteria is generally considered to be an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein n-acyltransferase. The mature lipoproteins are then sorted...

  17. Detection of AmpC β-lactamase-producing Gram-negative bacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Li, C; Ding, S; Huang, Y; Wang, Z; Shen, J; Ling, H; Xu, Y

    2017-11-22

    Rapid detection of AmpC-producing strains of Gram-negative bacteria is beneficial for patient care. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a novel method that has demonstrated the resistance of a strain to β-lactam antibiotics by determining the molecular structure of an antibiotic and its degradation products. To study the detection of AmpC-producing Gram-negative bacteria by MALDI-TOF MS and to determine whether the method can be used in clinical practice. A total of 105 strains were detected by determining their phenotypes and sequence analysis. Sixty-nine well-characterized AmpC-producing and 36 non-AmpC-producing strains were studied. The bacteria were incubated in different reaction buffer solutions (10 mM NH 4 HCO 3 /0.005% sodium dodecyl sulphate at pH 8.0) containing cefotaxime (0.50 mg/mL), ceftazidime (0.25 mg/mL), ceftriaxone (0.50 mg/mL), cefepime (0.50 mg/mL), and cefoxitin (0.25 and 0.50 mg/mL), respectively. The mixture was centrifuged at 13,000 g for 2 min, and the supernatant analysed by MALDI-TOF MS after incubation for 30, 60, 90, 120, and 240 min. Antibiotic hydrolysed and decarboxylated peaks were identified. When incubated for 90 min, hydrolysed cefotaxime formed peaks at 434 and 494 Da, and the sensitivity and specificity for detection of AmpC-producing strains were 85.5% (59/69) and 88.9% (32/36). When incubated for 4 h, hydrolysed ceftazidime formed peaks at 563 and 587 Da, and the sensitivity and specificity were 89.9% (62/69) and 94.5% (34/36), respectively. For hydrolysed ceftriaxone (0.5 mg/mL), cefepime (0.5 mg/mL) and two concentrations of cefoxitin (0.25 and 0.5 mg/mL), no peaks amenable to analysis were identified. This study demonstrated that MALDI-TOF MS can rapidly detect AmpC-producing strains. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Disinfection of Escherichia coli Gram negative bacteria using surface modified TiO2: optimization of Ag metallization and depiction of charge transfer mechanism.

    Science.gov (United States)

    Gomathi Devi, LakshmipathiNaik; Nagaraj, Basavalingaiah

    2014-01-01

    The antibacterial activity of silver deposited TiO2 (Ag-TiO2 ) against Gram negative Escherichia coli bacteria was investigated by varying the Ag metal content from 0.10 to 0.50% on the surface of TiO2 . Ag depositions by the photoreduction method were found to be stable. Surface silver metallization was confirmed by EDAX and XPS studies. Photoluminescence studies show that the charge carrier recombination is less for 0.1% Ag-TiO2 and this catalyst shows superior bactericidal activity under solar light irradiation compared to Sol gel TiO2 (SG-TiO2 ) due to the surface plasmon effect. The energy levels of deposited Ag are dependent on the Ag content and it varies from -4.64 eV to -1.30 eV with respect to the vacuum energy level based on atomic silver to bulk silver deposits. The ability of electron transfer from Ag deposit to O2 depends on the position of the energy levels. The 0.25% and 0.50% Ag depositions showed detrimental effect on bactericidal activity due to the mismatch of energy levels. The effect of the EROS (External generation of the Reactive Oxygen Species by 0.1% Ag-TiO2 ) and IROS (Interior generation of Reactive Oxygen Species within the bacteria) on the bactericidal inactivation is discussed in detail. © 2014 The American Society of Photobiology.

  19. Investigation of antifouling and disinfection potential of chitosan coated iron oxide-PAN hollow fiber membrane using Gram-positive and Gram-negative bacteria.

    Science.gov (United States)

    Mukherjee, Munmun; De, Sirshendu

    2017-06-01

    Chitosan coated iron oxide nanoparticles were impregnated into polyacrylonitrile based hollow fiber membrane. The molecular weight cut off was varied in the range of 120 to 145kDa with the concentration of nanoparticles. Incorporation of nanoparticles improved the permeability, mechanical property and hydrophilicity of the membrane. The contact angle of the membrane decreased from 80° to 51° and the permeability increased by 31% at 0.5wt% nanoparticles concentration. The antibacterial and antifouling property of the membrane were investigated with two biofilm causing Gram positive and Gram negative bacteria. The damage of cell membrane was directly confirmed by release of cellular constituent absorbing in 260nm. The cellular deformation on the membrane surface was evident by direct microscopic observation in FESEM. This damage was likely caused by electrostatic interaction between NH 3 + group of nanoparticles and anionic components of phosphoryl group of bacteria. The hollow fiber membrane shows promising antibiofouling property even after long experimental run as evident by 95% flux recovery ratio. The effect of operating conditions on rejection and flux profile was investigated during long experimental run. The result indicated that there was no detectable iron in the permeate sample that could impose adverse health hazard. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. ALPK1 controls TIFA/TRAF6-dependent innate immunity against heptose-1,7-bisphosphate of gram-negative bacteria.

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    Milica Milivojevic

    2017-02-01

    Full Text Available During infection by invasive bacteria, epithelial cells contribute to innate immunity via the local secretion of inflammatory cytokines. These are directly produced by infected cells or by uninfected bystanders via connexin-dependent cell-cell communication. However, the cellular pathways underlying this process remain largely unknown. Here we perform a genome-wide RNA interference screen and identify TIFA and TRAF6 as central players of Shigella flexneri and Salmonella typhimurium-induced interleukin-8 expression. We show that threonine 9 and the forkhead-associated domain of TIFA are necessary for the oligomerization of TIFA in both infected and bystander cells. Subsequently, this process triggers TRAF6 oligomerization and NF-κB activation. We demonstrate that TIFA/TRAF6-dependent cytokine expression is induced by the bacterial metabolite heptose-1,7-bisphosphate (HBP. In addition, we identify alpha-kinase 1 (ALPK1 as the critical kinase responsible for TIFA oligomerization and IL-8 expression in response to infection with S. flexneri and S. typhimurium but also to Neisseria meningitidis. Altogether, these results clearly show that ALPK1 is a master regulator of innate immunity against both invasive and extracellular gram-negative bacteria.

  1. The Effect of Charge at the Surface of Silver Nanoparticles on Antimicrobial Activity against Gram-Positive and Gram-Negative Bacteria: A Preliminary Study

    International Nuclear Information System (INIS)

    Abbaszadegan, A.; Ghahramani, Y.; Nabavizadeh, M.; Gholami, A.; Hemmateenejad, I.; Dorostkar, S.; Sharghi, H.

    2014-01-01

    The bactericidal efficiency of various positively and negatively charged silver nanoparticles has been extensively evaluated in literature, but there is no report on efficacy of neutrally charged silver nanoparticles. The goal of this study is to evaluate the role of electrical charge at the surface of silver nanoparticles on antibacterial activity against a panel of microorganisms. Three different silver nanoparticles were synthesized by different methods, providing three different electrical surface charges (positive, neutral, and negative). The antibacterial activity of these nanoparticles was tested against gram-positive (i.e., Staphylococcus aureus, Streptococcus mutans, and Streptococcus pyogenes) and gram-negative (i.e., Escherichia coli and Proteus vulgaris) bacteria. Well diffusion and micro-dilution tests were used to evaluate the bactericidal activity of the nanoparticles. According to the obtained results, the positively-charged silver nanoparticles showed the highest bactericidal activity against all microorganisms tested. The negatively charged silver nanoparticles had the least and the neutral nanoparticles had intermediate antibacterial activity. The most resistant bacteria were Proteus vulgaris. We found that the surface charge of the silver nanoparticles was a significant factor affecting bactericidal activity on these surfaces. Although the positively charged nanoparticles showed the highest level of effectiveness against the organisms tested, the neutrally charged particles were also potent against most bacterial species.

  2. Differential regulation of polysaccharide-specific antibody responses to isolated polysaccharides, conjugate vaccines, and intact Gram-positive versus Gram-negative extracellular bacteria.

    Science.gov (United States)

    Snapper, Clifford M

    2016-06-24

    Bacterial capsular polysaccharides are major virulence factors and are key targets in a number of licensed anti-bacterial vaccines. Their major characteristics are their large molecular weight and expression of repeating antigenic epitopes that mediate multivalent B cell receptor cross-linking. In addition, since the majority of these antigens cannot associate with MHC-II they fail to recruit CD4+ T cell help and are referred to as T cell-independent antigens. In this review I will discuss a series of studies from my laboratory that have underscored the importance of understanding polysaccharide-specific antibody responses within the context in which the PS is expressed (i.e. in isolation, as a component of conjugate vaccines, and expressed naturally by intact bacteria). We have shown that multivalent B cell receptor crosslinking, as mediated by polysaccharides, uniquely determines the qualitative response of the B cell to subsequent stimuli, but by itself is insufficient to induce antibody secretion or class switching. For these latter events to occur, second signals must act in concert with primary signals derived from the B cell receptor. The co-expression of polysaccharide and protein within intact bacteria promotes recruitment of CD4+ T cell help for the associated PS-specific IgG response, in contrast to isolated polysaccharides. Further, the particulate nature of extracellular bacteria confers properties to the polysaccharide-specific IgG response that makes it distinct immunologically from soluble conjugate vaccines. Finally, the underlying biochemical and/or structural differences that distinguish Gram-positive and Gram-negative bacteria appear to play critical roles in differentially regulating the associated polysaccharide-specific IgG responses to these groups of pathogens. These studies have a number of implications for the understanding and future design of polysaccharide-based vaccines. Published by Elsevier Ltd.

  3. Effects of Single Amino Acid Substitution on the Biophysical Properties and Biological Activities of an Amphipathic α-Helical Antibacterial Peptide Against Gram-Negative Bacteria

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    Juanjuan Tan

    2014-07-01

    Full Text Available An antimicrobial peptide, known as V13K, was utilized as the framework to study the effects of charge, hydrophobicity and helicity on the biophysical properties and biological activities of α-helical peptides. Six amino acids (Lys, Glu, Gly, Ser, Ala, and Leu were individually used to substitute the original hydrophobic valine at the selected sixteenth location on the non-polar face of V13K. The results showed that the single amino acid substitutions changed the hydrophobicity of peptide analogs as monitored by RP-HPLC, but did not cause significant changes on peptide secondary structures both in a benign buffer and in a hydrophobic environment. The biological activities of the analogs exhibited a hydrophobicity-dependent behavior. The mechanism of peptide interaction with the outer membrane and cytoplasmic membrane of Gram-negative bacteria was investigated. We demonstrated that this single amino acid substitution method has valuable potential for the rational design of antimicrobial peptides with enhanced activities.

  4. A family of promoter probe vectors incorporating autofluorescent and chromogenic reporter proteins for studying gene expression in Gram-negative bacteria.

    Science.gov (United States)

    Karunakaran, R; Mauchline, T H; Hosie, A H F; Poole, P S

    2005-10-01

    A series of promoter probe vectors for use in Gram-negative bacteria has been made in two broad-host-range vectors, pOT (pBBR replicon) and pJP2 (incP replicon). Reporter fusions can be made to gfpUV, gfpmut3.1, unstable gfpmut3.1 variants (LAA, LVA, AAV and ASV), gfp+, dsRed2, dsRedT.3, dsRedT.4, mRFP1, gusA or lacZ. The two vector families, pOT and pJP2, are compatible with one another and share the same polylinker for facile interchange of promoter regions. Vectors based on pJP2 have the advantage of being ultra-stable in the environment due to the presence of the parABCDE genes. As a confirmation of their usefulness, the dicarboxylic acid transport system promoter (dctA(p)) was cloned into a pOT (pRU1097)- and a pJP2 (pRU1156)-based vector and shown to be expressed by Rhizobium leguminosarum in infection threads of vetch. This indicates the presence of dicarboxylates at the earliest stages of nodule formation.

  5. An original deal for new molecule: reversal of efflux pump activity, a rational strategy to combat gram-negative resistant bacteria.

    Science.gov (United States)

    Pagès, J-M; Amaral, L; Fanning, S

    2011-01-01

    The worldwide dissemination of «multi-drug resistant» (MDR) pathogens has severely reduced the efficacy of our antibiotic arsenal and increased the frequency of therapeutic failure. MDR bacteria over-express efflux pumps and this active mechanism can extrude all classes of antibiotics from the cell. It is necessary to clearly decipher the genetic, structural and functional aspects of this transport system in order to combat this polyselective mechanism. By understanding how efflux pumps work we may be able to develop a new group of antibacterial agents, collectively termed efflux reversals, including membrane permeabilisers, efflux pump inhibitors and flux-competitive agents, specific blockers, energy poisons, etc. Several chemical families of efflux pump inhibitors have been described and characterized. Among them several inhibitor compounds demonstrate efficient blocking of the efflux pump activity involved in the MDR phenotype as observed in many Gram-negative clinical isolates. This new family of molecules represents the first antibacterial class of compound specifically targeting active transport in the bacterial cell.

  6. Serum procalcitonin elevation in critically ill patients at the onset of bacteremia caused by either Gram negative or Gram positive bacteria.

    Science.gov (United States)

    Charles, Pierre Emmanuel; Ladoire, Sylvain; Aho, Serge; Quenot, Jean-Pierre; Doise, Jean-Marc; Prin, Sébastien; Olsson, Niels-Olivier; Blettery, Bernard

    2008-03-26

    In the ICU, bacteremia is a life-threatening infection whose prognosis is highly dependent on early recognition and treatment with appropriate antibiotics. Procalcitonin levels have been shown to distinguish between bacteremia and noninfectious inflammatory states accurately and quickly in critically ill patients. However, we still do not know to what extent the magnitude of PCT elevation at the onset of bacteremia varies according to the Gram stain result. Review of the medical records of every patient treated between May, 2004 and December, 2006 who had bacteremia caused by either Gram positive (GP) or Gram negative (GN) bacteria, and whose PCT dosage at the onset of infection was available. 97 episodes of either GN bacteremia (n = 52) or GP bacteremia (n = 45) were included. Procalcitonin levels were found to be markedly higher in patients with GN bacteremia than in those with GP bacteremia, whereas the SOFA score value in the two groups was similar. Moreover, in the study population, a high PCT value was found to be independently associated with GN bacteremia. A PCT level of 16.0 ng/mL yielded an 83.0% positive predictive value and a 74.0% negative predictive value for GN-related bacteremia in the study cohort (AUROCC = 0.79; 95% CI, 0.71-0.88). In a critically ill patient with clinical sepsis, GN bacteremia could be associated with higher PCT values than those found in GP bacteremia, regardless of the severity of the disease.

  7. Antimicrobial Activity of Ceftazidime-Avibactam against Gram-Negative Bacteria Isolated from Patients Hospitalized with Pneumonia in U.S. Medical Centers, 2011 to 2015.

    Science.gov (United States)

    Sader, Helio S; Castanheira, Mariana; Flamm, Robert K

    2017-04-01

    Bacterial isolates were collected from patients hospitalized with pneumonia (PHP), including ventilator-associated pneumonia (VAP), from 76 U.S. medical centers in 2011 to 2015. The Gram-negative organisms ( n = 11,185, including 1,097 from VAP) were tested for susceptibility to ceftazidime-avibactam and comparators by the broth microdilution method. β-Lactamase-encoding genes were screened using a microarray-based assay on selected isolates. Pseudomonas aeruginosa and Klebsiella spp. were the most common Gram-negative bacteria isolated from PHP and VAP. Ceftazidime-avibactam was very active against P. aeruginosa ( n = 3,402; MIC 50 /MIC 90 , 2 and 4 μg/ml; 96.6% susceptible), including isolates nonsusceptible to meropenem (86.3% susceptible to ceftazidime-avibactam), piperacillin-tazobactam (85.6% susceptible), or ceftazidime (80.6% susceptible). Ceftazidime-avibactam was also highly active against Enterobacteriaceae (MIC 50 /MIC 90 , 0.12 and 0.5 μg/ml; 99.9% susceptible), including carbapenem-resistant Enterobacteriaceae (CRE) ( n = 189; MIC 50 /MIC 90 , 0.5 and 2 μg/ml; 98.0% susceptible) and multidrug-resistant (MDR) ( n = 674; MIC 50 /MIC 90 , 0.25 and 1 μg/ml; 98.8% susceptible) and extensively drug-resistant (XDR) ( n = 156; MIC 50 /MIC 90 , 0.5 and 2 μg/ml; 98.1% susceptible) Enterobacteriaceae isolates, as well as Klebsiella species isolates showing an extended-spectrum β-lactamase (ESBL) screening-positive phenotype ( n = 433; MIC 50 /MIC 90 , 0.25 and 1 μg/ml; 99.5% susceptible). Among Enterobacter spp. (24.8% ceftazidime nonsusceptible), 99.8% of the isolates, including 99.4% of ceftazidime-nonsusceptible isolates, were susceptible to ceftazidime-avibactam. The most common β-lactamases detected among Klebsiella pneumoniae and E. coli isolates were K. pneumoniae carbapenemase (KPC)-like and CTX-M-15, respectively. Only 8 of 6,209 Enterobacteriaceae isolates (0.1%) were ceftazidime-avibactam nonsusceptible, three NDM-1-producing strains with

  8. A functional MSBBA cyltransferaseof photorhabdus luminescens, required for secondary lipid aacylation in gram-negative bacteria,confers resistance to anti-microbial peptides

    International Nuclear Information System (INIS)

    Abi Khattar, Z.; Gaudriault, S.; Givaudan, A.

    2016-01-01

    Lipid A is a potent endotoxin, and its fatty acids (lauric, myristic, and sometimes palmitic acid) anchors lipopolysaccharide (LPS) into the outer leaflet of the outer membrane of most Gram-negative bacteria. The highly anionic charge of the glucosamine lipid A moiety makes the LPS a powerful attractant for cationic antimicrobial peptides (AMPs). AMPs are major component of innate immunity that kill bacteria by permeabilization of lipid bilayers. Secondary lipid A acylation of Klebsiella pneumoniae, involving the acyltransferase LpxM (formally, msbBor WaaN) that acylates (KDO)2-(lauroyl)-lipid IV-A with myristate during lipid A biosynthesis, has been associated with bacterial resistanceto AMPs contributing to virulence in animal models. We investigated here the role of the msbB gene of the entomopathogenic bacterium Photorhabdus luminescens in AMP resistance, by functional complementation of the AMP susceptible K. pneumoniae lpxM mutant with the P. luminescens msbB gene. We showed that msbB (lpxM) gene of P. luminescensis able to enhance polymyxin B, colistin and cecropin A resistance of K. pneumoniae lpxM mutant, compared to the non-complemented mutant. However, we could not obtain any msbB mutant of Photorhabdus by performing allelic exchange experiments based on positive selection of sucrose highly resistant mutants.We thus suggest that msbB-mediated Photorhabdus lipid A acylation is essential for outer membrane low-permeability and thatmodification of lipid A composition, fluidity and osmosis-resistance have an important role in the ability of Photorhabdus to grow in sucrose at high concentrations. (author)

  9. Antibacterial activities of the methanol extracts of Canarium schweinfurthii and four other Cameroonian dietary plants against multi-drug resistant Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Joachim K. Dzotam

    2016-09-01

    Full Text Available Bacterial infections are among the major cause of morbidity and mortality worldwide. The present study was designed to evaluate the in vitro antibacterial activities of the methanol extracts of five Cameroonian edible plants namely Colocasia esculenta, Triumfetta pentandra, Hibiscus esculentus, Canarium schweinfurthii and Annona muricata against a panel of 19 multidrug resistant Gram-negative bacterial strains. The liquid broth microdilution was used to determine the minimal inhibitory concentration (MIC and minimal bactericidal concentration (MBC of the extracts. The preliminary phytochemical screening of the extracts was conducted according to the standard phytochemical methods. Results showed that all extracts contained compounds belonging to the classes of polyphenols, triterpenes and steroids, other classes of chemicals being selectively distributed. Canarium schweinfurthii extract showed the best activity with MIC values ranging from 64 to 1024 μg/mL against 89.5% of the 19 tested bacteria strains. MIC values below or equal to 1024 μg/mL were also recorded with Triumfetta pentandra, Annona muricata, Colocasia esculenta and Hibiscus esculentus extracts respectively against 15/19 (78.9%, 11/19 (57.9%, 10/19 (52.6% and 10/19 (52.6% tested bacteria. Extract from C. schweinfurthii displayed the lowest MIC value (64 μg/mL against Escherichia coli AG100ATet. Finally, the results of this work provide baseline information for the use of C. esculenta, T. pentandra, H. esculentus, C. schweinfurthii and A. muricata in the treatment of bacterial infections including multidrug resistant phenotypes.

  10. Silver nanocrystallites: Facile biofabrication using Shewanella oneidensis, and an evaluation of their comparative toxicity on Gram-negative and Gram-positive bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, Anil K [ORNL; Wang, Wei [ORNL; Pelletier, Dale A [ORNL; Moon, Ji Won [ORNL; Gu, Baohua [ORNL; Mortensen, Ninell P [ORNL; Allison, David P [ORNL; Joy, David Charles [ORNL; Phelps, Tommy Joe [ORNL; Doktycz, Mitchel John [ORNL

    2010-01-01

    Microorganisms have long been known to develop resistance to metal ions either by sequestering metals inside the cell or by effluxing them into the extracellular media. Here we report the biosynthesis of extracellular silver based single nanocrystallites of well-defined composition and homogeneous morphology utilizing the -proteobacterium, Shewanella oneidensis strain MR-1, upon incubation with an aqueous solution of silver nitrate. Further characterization of these particles revealed that the crystals consist of small, reasonably monodispersed spheres in the size range 2 11 nm (with an average of 4 1.5 nm). The bactericidal effect of these biologically synthesized silver nanoparticles (biogenic-Ag) are compared to similar chemically synthesized nanoparticles (colloidal silver [colloidal-Ag] and oleate capped silver [oleate-Ag]). The determination of the bactericidal effect of these different silver nanoparticles was assessed using both Gram-negative (E. coli) and Gram-positive (B. subtilis) bacteria and based on the diameter of the inhibition zone in disc diffusion tests, minimum inhibitory concentrations, Live/Dead staining assays, and atomic force microscopy. From a toxicity perspective, a clear synthesis procedure, and a surface coat- and strain-dependent inhibition were observed for silver nanoparticles. Biogenic-Ag was found to be of higher toxicity when compared to colloidal-Ag for both E. coli and B. subtilis. E. coli was found to be more resistant to either of these nanoparticles than B. subtilis. In contrast, Oleate-Ag was not toxic to either of the bacteria. These findings have important implications for the potential uses of Ag nanomaterials and for their fate in biological and environmental systems.

  11. Revisiting the Gram-negative lipoprotein paradigm.

    Science.gov (United States)

    LoVullo, Eric D; Wright, Lori F; Isabella, Vincent; Huntley, Jason F; Pavelka, Martin S

    2015-05-01

    The processing of lipoproteins (Lpps) in Gram-negative bacteria is generally considered an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein N-acyltransferase. The mature lipoproteins are then sorted by the Lol system, with most Lpps inserted into the outer membrane (OM). We demonstrate here that the lnt gene is not essential to the Gram-negative pathogen Francisella tularensis subsp. tularensis strain Schu or to the live vaccine strain LVS. An LVS Δlnt mutant has a small-colony phenotype on sucrose medium and increased susceptibility to globomycin and rifampin. We provide data indicating that the OM lipoprotein Tul4A (LpnA) is diacylated but that it, and its paralog Tul4B (LpnB), still sort to the OM in the Δlnt mutant. We present a model in which the Lol sorting pathway of Francisella has a modified ABC transporter system that is capable of recognizing and sorting both triacylated and diacylated lipoproteins, and we show that this modified system is present in many other Gram-negative bacteria. We examined this model using Neisseria gonorrhoeae, which has the same Lol architecture as that of Francisella, and found that the lnt gene is not essential in this organism. This work suggests that Gram-negative bacteria fall into two groups, one in which full lipoprotein processing is essential and one in which the final acylation step is not essential, potentially due to the ability of the Lol sorting pathway in these bacteria to sort immature apolipoproteins to the OM. This paper describes the novel finding that the final stage in lipoprotein processing (normally considered an essential process) is not required by Francisella tularensis or Neisseria gonorrhoeae. The paper provides a potential reason for this and shows that it may be widespread in other Gram-negative bacteria. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  12. Prevalence of Device-associated Nosocomial Infections Caused By Gram-negative Bacteria in a Trauma Intensive Care Unit in Libya

    Directory of Open Access Journals (Sweden)

    Abdulaziz Zorgani

    2015-07-01

    Full Text Available Objectives: Device-associated nosocomial infections (DANIs have a major impact on patient morbidity and mortality. Our study aimed to determine the distribution rate of DANIs and causative agents and patterns of antibiotic resistance in the trauma-surgical intensive care unit (ICU. Methods: Our study was conducted at Abusalim Trauma Hospital in Tripoli, Libya. All devices associated with nosocomial infections, including central venous catheters (CVC, endotracheal tubes (ETT, Foley’s urinary catheters, chest tubes, nasogastric tubes (NGT, and tracheostomy tubes, were removed aseptically and examined for Gram-negative bacteria (GNB. Results: During a one-year study period, 363 patients were hospitalized; the overall mortality rate was 29%. A total of 79 DANIs were identified, the most common site of infection was ETT (39.2%, followed by urinary catheters (19%, NGTs (18%, tracheostomy tubes (11%, CVCs (10%, and chest tubes (3%. The most frequently isolated organisms were Klebsiella pneumonia, Acinetobacter baumannii, and Pseudomonas aeruginosa (30%, 20%, and 14%, respectively. Extremely high resistance rates were observed among GNB to ampicillin (99%, cefuroxime (95%, amoxicillin-clavulante (92%, and nitrofurantoin (91%. Lower levels of resistance were exhibited to amikacin (38%, imipenem (38%, and colistin (29%. About 39% of the isolates were defined as multi-drug resistant (MDR. Overall, extended spectrum β-lactmase producers were expressed in 39% of isolates mainly among K. pneumonia (88%. A. baumannii isolates exhibited extremely high levels of resistance to all antibiotics except colistin (100% sensitive. In addition, 56.3% of A. baumannii isolates were found to be MDR. P. aeruginosa isolates showed 46%–55% effectiveness to anti-pseudomonas antibiotics. Conclusion: High rates of DANI’s and the emergence of MDR organisms poses a serious threat to patients. There is a need to strengthen infection control within the ICU environment

  13. Extracellular vesicles derived from Gram-negative bacteria, such as Escherichia coli, induce emphysema mainly via IL-17A-mediated neutrophilic inflammation.

    Science.gov (United States)

    Kim, You-Sun; Lee, Won-Hee; Choi, Eun-Jeong; Choi, Jun-Pyo; Heo, Young Joo; Gho, Yong Song; Jee, Young-Koo; Oh, Yeon-Mok; Kim, Yoon-Keun

    2015-04-01

    Recent evidence indicates that Gram-negative bacteria-derived extracellular vesicles (EVs) in indoor dust can evoke neutrophilic pulmonary inflammation, which is a key pathology of chronic obstructive pulmonary disease (COPD). Escherichia coli is a ubiquitous bacterium present in indoor dust and secretes nanometer-sized vesicles into the extracellular milieu. In the current study, we evaluated the role of E. coli-derived EVs on the development of COPD, such as emphysema. E. coli EVs were prepared by sequential ultrafiltration and ultracentrifugation. COPD phenotypes and immune responses were evaluated in C57BL/6 wild-type (WT), IFN-γ-deficient, or IL-17A-deficient mice after airway exposure to E. coli EVs. The present study showed that indoor dust from a bed mattress harbors E. coli EVs. Airway exposure to E. coli EVs increased the production of proinflammatory cytokines, such as TNF-α and IL-6. In addition, the repeated inhalation of E. coli EVs for 4 wk induced neutrophilic inflammation and emphysema, which are associated with enhanced elastase activity. Emphysema and elastase activity enhanced by E. coli EVs were reversed by the absence of IFN-γ or IL-17A genes. In addition, during the early period, lung inflammation is dependent on IL-17A and TNF-α, but not on IFN-γ, and also on TLR4. Moreover, the production of IFN-γ is eliminated by the absence of IL-17A, whereas IL-17A production is not abolished by IFN-γ absence. Taken together, the present data suggest that E. coli-derived EVs induce IL-17A-dependent neutrophilic inflammation and thereby emphysema, possibly via upregulation of elastase activity. Copyright © 2015 by The American Association of Immunologists, Inc.

  14. Colistin for the treatment of ventilator-associated pneumonia caused by multidrug-resistant Gram-negative bacteria: a systematic review and meta-analysis.

    Science.gov (United States)

    Gu, Wan-Jie; Wang, Fei; Tang, Lu; Bakker, Jan; Liu, Jing-Chen

    2014-12-01

    Ventilator-associated pneumonia (VAP) caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) has emerged as an important and intractable clinical problem. This review assessed the efficacy and safety of colistin for treatment of MDR GNB VAP. PubMed and Embase were searched for controlled studies of colistin for treatment of MDR GNB VAP. The Mantel-Haenszel random-effects model was used to pool odds ratios (ORs) with 95% confidence intervals (CIs). The primary outcome was clinical cure; secondary outcomes were microbiological eradication, ICU mortality, hospital mortality, length of ICU stay and nephrotoxicity. Fourteen controlled studies involving 1167 patients were identified, including six reporting colistin versus β-lactam antibiotics, three reporting aerosolised (AS) plus intravenous (IV) colistin versus IV colistin alone and five reporting colistin combined therapy versus colistin monotherapy. The clinical cure rate of colistin was comparable with that of β-lactam antibiotics (OR=1.00, 95% CI 0.68-1.47). Compared with IV colistin alone, AS plus IV colistin exhibited a better clinical cure (OR=2.12, 95% CI 1.40-3.20). Compared with colistin monotherapy, colistin combined therapy did not appear to provide a better clinical cure (OR=1.38, 95% CI 0.81-2.33). There was no significant difference in nephrotoxicity and other secondary outcomes between the treatment groups. Colistin appears as effective and safe as β-lactam antibiotics for the treatment of MDR GNB VAP. AS colistin may be a beneficial adjunct to IV colistin in the management of MDR GNB VAP. Colistin combined therapy does not appear to provide better outcomes compared with colistin monotherapy. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  15. Burdock (Arctium lappa Leaf Extracts Increase the In Vitro Antimicrobial Efficacy of Common Antibiotics on Gram-positive and Gram-negative Bacteria

    Directory of Open Access Journals (Sweden)

    Pirvu Lucia

    2017-04-01

    Full Text Available This work aimed to study the potential effects of four Arctii folium extracts, 5 mg gallic [GAE] acid equivalents per 1 mL sample, on six antibiotics (Ampicillin/AM, Tetracycline/TE, Ciprofloxacin/CIP, Sulfamethoxazole-Trimethoprim/SXT, Chloramphenicol/C and Gentamicin/CN tested on four Gram-positive (Staphylococcus aureus ATCC 6538, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, and Staphylococcus epidermidis ATCC 12228 and five Gram-negative (Proteus mirabilis ATCC 29245, Escherichia coli ATCC 35218, E. coli ATCC 11229, E. coli ATCC 8739, and Bacillus cereus ATCC 11778 bacteria. Arctii folium extracts were the whole ethanol extract/W and subsequent ethyl acetate/EA, aqueous/AQ, and chloroform/CHL fractions. Chemical qualitative analysis (HPTLC method emphasized five main polyphenol compounds in Arctii folium polar extracts: chlorogenic acid (Rf≈0.52/0.55 and its isomer, 1,5-di-O-caffeoylquinic acid (Rf≈0.90/0.92, plus cynarin (Rf≈0.77, hyperoside (Rf≈0.68/0.64 and isoquercitrin (Rf≈0.69/0.71. Microbiological screening indicated Arctii folium polar extracts (AQ and W efficacy on S. epidermidis ATCC 12228; the MIC values were in the range of common antibiotics, being 32 and 128 μg GAE per mL sample respectively. The unpredictable effects (stimulatory or inhibitory of Arctii folium extracts in combination with typical antibiotics as well as a potential use of the whole ethanol extract/W for restoring the antimicrobial potency of susceptible antibiotics have also been evidenced.

  16. Serum procalcitonin elevation in critically ill patients at the onset of bacteremia caused by either gram negative or gram positive bacteria

    Directory of Open Access Journals (Sweden)

    Prin Sébastien

    2008-03-01

    Full Text Available Abstract Background In the ICU, bacteremia is a life-threatening infection whose prognosis is highly dependent on early recognition and treatment with appropriate antibiotics. Procalcitonin levels have been shown to distinguish between bacteremia and noninfectious inflammatory states accurately and quickly in critically ill patients. However, we still do not know to what extent the magnitude of PCT elevation at the onset of bacteremia varies according to the Gram stain result. Methods Review of the medical records of every patient treated between May, 2004 and December, 2006 who had bacteremia caused by either Gram positive (GP or Gram negative (GN bacteria, and whose PCT dosage at the onset of infection was available. Results 97 episodes of either GN bacteremia (n = 52 or GP bacteremia (n = 45 were included. Procalcitonin levels were found to be markedly higher in patients with GN bacteremia than in those with GP bacteremia, whereas the SOFA score value in the two groups was similar. Moreover, in the study population, a high PCT value was found to be independently associated with GN bacteremia. A PCT level of 16.0 ng/mL yielded an 83.0% positive predictive value and a 74.0% negative predictive value for GN-related bacteremia in the study cohort (AUROCC = 0.79; 95% CI, 0.71–0.88. Conclusion In a critically ill patient with clinical sepsis, GN bacteremia could be associated with higher PCT values than those found in GP bacteremia, regardless of the severity of the disease.

  17. Prevention and Control of Multidrug-Resistant Gram-Negative Bacteria in Adult Intensive Care Units: A Systematic Review and Network Meta-analysis.

    Science.gov (United States)

    Teerawattanapong, Nattawat; Kengkla, Kirati; Dilokthornsakul, Piyameth; Saokaew, Surasak; Apisarnthanarak, Anucha; Chaiyakunapruk, Nathorn

    2017-05-15

    This study evaluated the relative efficacy of strategies for the prevention of multidrug-resistant gram-negative bacteria (MDR-GNB) in adult intensive care units (ICUs). A systematic review and network meta-analysis was performed; searches of the Cochrane Library, PubMed, Embase, and CINAHL (Cumulative Index to Nursing and Allied Health Literature) included all randomized controlled trials and observational studies conducted in adult patients hospitalized in ICUs and evaluating standard care (STD), antimicrobial stewardship program (ASP), environmental cleaning (ENV), decolonization methods (DCL), or source control (SCT), simultaneously. The primary outcomes were MDR-GNB acquisition, colonization, and infection; secondary outcome was ICU mortality. Of 3805 publications retrieved, 42 met inclusion criteria (5 randomized controlled trials and 37 observational studies), involving 62068 patients (median age, 58.8 years; median APACHE [Acute Physiology and Chronic Health Evaluation] II score, 18.9). The majority of studies reported extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and MDR Acinetobacter baumannii. Compared with STD, a 4-component strategy composed of STD, ASP, ENV, and SCT was the most effective intervention (rate ratio [RR], 0.05 [95% confidence interval {CI}, .01-.38]). When ENV was added to STD+ASP or SCT was added to STD+ENV, there was a significant reduction in the acquisition of MDR A. baumannii (RR, 0.28 [95% CI, .18-.43] and 0.48 [95% CI, .35-.66], respectively). Strategies with ASP as a core component showed a statistically significant reduction the acquisition of ESBL-producing Enterobacteriaceae (RR, 0.28 [95% CI, .11-.69] for STD+ASP+ENV and 0.23 [95% CI, .07-.80] for STD+ASP+DCL). A 4-component strategy was the most effective intervention to prevent MDR-GNB acquisition. As some strategies were differential for certain bacteria, our study highlighted the need for further evaluation of the most effective prevention strategies

  18. Emergence and Acquisition of Fluoroquinolone-Resistant Gram-Negative Bacilli in the Intestinal Tracts of Mice Treated with Fluoroquinolone Antimicrobial Agents▿

    OpenAIRE

    Pultz, Michael J.; Nerandzic, Michelle M.; Stiefel, Usha; Donskey, Curtis J.

    2008-01-01

    After mice received orogastric administration of a fluoroquinolone-resistant Klebsiella pneumoniae strain, subcutaneous treatment with ciprofloxacin, levofloxacin, and moxifloxacin promoted persistent low-density colonization in 10% to 40% of the mice, whereas treatment with clindamycin consistently promoted high-density colonization. No emergence of fluoroquinolone-resistant gram-negative bacilli was detected in the mice during or after treatment with the fluoroquinolone antimicrobial agents.

  19. Tigecycline Therapy for Nosocomial Pneumonia due to Carbapenem-Resistant Gram-Negative Bacteria in Critically Ill Patients Who Received Inappropriate Initial Antibiotic Treatment: A Retrospective Case Study.

    Science.gov (United States)

    Wu, Xiaomai; Zhu, Yefei; Chen, Qiuying; Gong, Liuyang; Lin, Jian; Lv, Dongqing; Feng, Jiaxi

    2016-01-01

    Background . Nosocomial pneumonia due to carbapenem-resistant Gram-negative bacteria (CRGNB) is a growing concern because treatment options are limited and the mortality rate is high. The effect of tigecycline (TGC) on nosocomial pneumonia due to CRGNB in patients who have received inappropriate initial empiric antibiotic treatment (IIAT) is unclear. Therefore, this study aimed to examine the effect of TGC on nosocomial pneumonia due to CRGNB in critically ill patients who had received IIAT. Methods . A retrospective study was conducted in an adult respiratory intensive care unit. Data were obtained and analyzed for all patients who were treated with TGC ≥ 3 days for microbiologically confirmed nosocomial pneumonia due to CRGNB and had experienced initial antibiotic failure. Clinical and microbiological outcomes were investigated. Results . Thirty-one patients with hospital-acquired pneumonia or ventilator-associated pneumonia were included in the study. The majority of the responsible organisms were carbapenem-resistant Acinetobacter baumannii (67.7%), followed by Klebsiella pneumoniae (16.1%) and Escherichia coli (9.7%). Twenty patients were treated with high-dose TGC therapy (100 mg every 12 h after a 200 mg loading dose), and the others received a standard-dose therapy (50 mg every 12 h after a 100 mg loading dose). The duration of TGC therapy was 14.3 ± 2.8 days. The global clinical cure rate and the microbiological eradication rate were 48.4% and 61.3%, respectively. The overall ICU mortality rate was 45.2%. A higher score on the Acute Physiology and Chronic Health Evaluation II and a longer duration of IIAT were associated with clinical failure. High-dose TGC therapy had a higher clinical success rate [65.0% (13/20) versus 18.2% (2/11), P = 0.023] and a lower ICU mortality rate [30.0% (6/20) versus 72.7% (8/11), P = 0.031] than the standard-dose therapy. Conclusions . TGC, especially a high-dose regimen, might be a justifiable option for

  20. In vitro susceptibility of gram-negative bacterial isolates to ...

    African Journals Online (AJOL)

    In vitro susceptibility of gram-negative bacterial isolates to chlorhexidine gluconate. Y Mengistu, W Erge, B Bellete. Abstract. Objective: To investigate the susceptibility of clinical isolates of gram-negative bacteria to chlorhexidine gluconate. Design: Prospective laboratory study. Setting: Tikur Anbessa Hospital, Addis Ababa, ...

  1. Effect of silver/copper and copper oxide nanoparticle powder on growth of Gram-negative and Gram-positive bacteria and their toxicity against the normal human dermal fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Peszke, Jerzy; Nowak, Anna, E-mail: ana.maria.nowak@gmail.com; Szade, Jacek; Szurko, Agnieszka; Zygadło, Dorota; Michałowska, Marlena [University of Silesia, A. Chelkowski Institute of Physics (Poland); Krzyściak, Paweł [Jagiellonian University Medical College, Department of Mycology Chair of Microbiology (Poland); Zygoń, Patrycja [Czestochowa University of Technology, Institute of Materials Engineering (Poland); Ratuszna, Alicja [University of Silesia, A. Chelkowski Institute of Physics (Poland); Ostafin, Marek M. [Department of Microbiology University of Agriculture (Poland)

    2016-12-15

    Engineered nanomaterials, especially metallic nanoparticles, are the most popular system applied in daily life products. The study of their biological and toxicity properties seems to be indispensable. In this paper, we present results of biological activity of Ag/Cu nanoparticles. These nanoparticles show more promising killing/inhibiting properties on Gram-negative bacteria than for Gram-positive ones. The Gram-negative bacteria show strong effect already at the concentration of 1 ppm after 15 min of incubation. Moreover, in vitro tests of toxicity made on normal human dermal fibroblast cultures showed that after 72 h of incubation with Ag/Cu nanoparticles, they are less toxic then Cu{sub 2}O/CuO nanoparticles.

  2. Effect of silver/copper and copper oxide nanoparticle powder on growth of Gram-negative and Gram-positive bacteria and their toxicity against the normal human dermal fibroblasts

    International Nuclear Information System (INIS)

    Peszke, Jerzy; Nowak, Anna; Szade, Jacek; Szurko, Agnieszka; Zygadło, Dorota; Michałowska, Marlena; Krzyściak, Paweł; Zygoń, Patrycja; Ratuszna, Alicja; Ostafin, Marek M.

    2016-01-01

    Engineered nanomaterials, especially metallic nanoparticles, are the most popular system applied in daily life products. The study of their biological and toxicity properties seems to be indispensable. In this paper, we present results of biological activity of Ag/Cu nanoparticles. These nanoparticles show more promising killing/inhibiting properties on Gram-negative bacteria than for Gram-positive ones. The Gram-negative bacteria show strong effect already at the concentration of 1 ppm after 15 min of incubation. Moreover, in vitro tests of toxicity made on normal human dermal fibroblast cultures showed that after 72 h of incubation with Ag/Cu nanoparticles, they are less toxic then Cu 2 O/CuO nanoparticles.

  3. Optimization of routine identification of clinically relevant Gram-negative bacteria by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry and the Bruker Biotyper.

    Science.gov (United States)

    Ford, Bradley A; Burnham, Carey-Ann D

    2013-05-01

    Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) might complement and one day replace phenotypic identification of bacteria in the clinical microbiology laboratory, but there is no consensus standard regarding the requirements for its validation prior to clinical use in the United States. The objective of this study was to assess the preanalytical variables influencing Gram-negative identification by use of the Bruker Biotyper MALDI-TOF MS system, including density of organism spotting on a stainless steel target plate and the direct overlay of organisms with formic acid. A heavy smear with formic acid overlay was either superior or equivalent to alternative smear conditions. Microbiological preanalytical variables were also assayed, such as culture medium, growth temperature, and use of serial subculture. Postanalytical analysis included the application of modified species-level identification acceptance criteria. Biotyper identifications were compared with those using traditional phenotypic methods, and discrepancies were resolved with 16S rRNA gene sequencing. Compared to the recommended score cutoffs of the manufacturer, the application of optimized Biotyper score cutoffs for species-level identification increased the rate of identification by 6.75% for the enteric Gram-negative bacteria and 4.25% for the nonfermenting Gram-negative bacteria. Various incubation temperatures, growth medium types, and repeat subcultures did not result in misidentification. We conclude that the Bruker MALDI Biotyper is a robust system for the identification of Gram-negative organisms in the clinical laboratory and that meaningful performance improvements can be made by implementing simple pre- and postanalytical techniques.

  4. Extended-spectrum beta-lactamase producing gram negative ...

    African Journals Online (AJOL)

    ESBL)-producing Gram- negative bacteria (GNB), particularly in Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas aeruginosa, have increased all over the world. ESBLs are characterized by their ability to hydrolyze β-lactams, ...

  5. Competitive binding of polyethyleneimine-coated gold nanoparticles to enzymes and bacteria: a key mechanism for low-level colorimetric detection of gram-positive and gram-negative bacteria

    International Nuclear Information System (INIS)

    Thiramanas, Raweewan; Laocharoensuk, Rawiwan

    2016-01-01

    The article describes a simple and rapid method for colorimetric detection of bacteria. It is based on competitive binding of positively charged polyethyleneimine-coated gold nanoparticles (PEI-AuNPs) to negatively charged enzymes and bacteria. The PEI-AuNPs are electrostatically attracted by both the bacterial surface and the enzyme β-galactosidase (β-Gal). Binding to the latter results in the inhibition of enzyme activity. However, in the presence of a large number of bacteria, the PEI-AuNPs preferentially bind to bacteria. Hence, the enzyme will not be inhibited and its activity can be colorimetrically determined via hydrolysis of the chromogenic substrate chlorophenol red β-D-galactopyranoside (CPRG). The detection limit of this assay is as low as 10 cfu·mL −1 , and the linear range extends from 10 6 to 10 8 cfu·mL −1 . The assay is applicable to both Gram-negative (such as enterotoxigenic Escherichia coli; ETEC) and Gram-positive (Staphylococcus aureus; S. aureus) bacteria. Results are obtained within 10 min using an optical reader, and within 2–3 h by bare-eye detection. The method was applied to the identification of ETEC contamination at a level of 10 cfu·mL −1 in spiked drinking water. Given its low detection limit and rapidity (sample preconcentration is not required), this method holds great promise for on-site detection of total bacterial contamination. (author)

  6. Microbial Adhesion to Processing Lines for Fish Fillets and Cooked Shrimp: Influence of Stainless Steel Surface Finish and Presence of Gram-Negative Bacteria on the Attachment of Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Hjörleifur Einarsson

    2005-01-01

    Full Text Available Microflora adhering to surfaces of processing lines in a shrimp factory and a fish processing plant was identified in situ and adhesion of mixed culture of Listeria monocytogenes and Gram-negative bacteria on stainless steel surfaces (untreated, polished and glass beaded was studied ex situ. The predominant genus attached to the surfaces was Pseudomonas spp. (66 % in the shrimp factory and Enterobacteriaceae (27 % in the fish factory. Shrimp juice was used as an enrichment broth during the study of adhered bacteria. Three different Gram-negative strains and a mixture of Pseudomonas spp. were selected to study their attachment together with L. monocytogenes to stainless steel surfaces. Highest numbers of the attached bacteria were obtained after the contamination with a mixed culture of L. monocytogenes and Serratia liquefaciens. A lower number of bacteria adhered to stainless steel surfaces when mixed cultures of L. monocytogenes and Pseudomonas fluorescens or Aeromonas spp. were tested. No significant differences (p<0.05 were observed in the bacteria attached to differently treated steel surfaces with different roughness (Ra=0.1–0.8 m. Bacterial adhesion increased with longer contact time. Colonisation of L. monocytogenes on stainless steel surfaces was significantly enhanced only in the presence of mixed Pseudomonas spp. These results indicate that smooth surfaces do not necessarily provide hygiene benefits over rougher surfaces.

  7. Lipoprotein Transport: Greasing the Machines of Outer Membrane Biogenesis: Re-Examining Lipoprotein Transport Mechanisms Among Diverse Gram-Negative Bacteria While Exploring New Discoveries and Questions.

    Science.gov (United States)

    Grabowicz, Marcin

    2018-04-01

    The Gram-negative outer membrane (OM) is a potent permeability barrier against antibiotics, limiting clinical options amid mounting rates of resistance. The Lol transport pathway delivers lipoproteins to the OM. All the OM assembly machines require one or more OM lipoprotein to function, making the Lol pathway central for all aspects of OM biogenesis. The Lol pathways of many medically important species clearly deviate from the Escherichia coli paradigm, perhaps with implications for efforts to develop novel antibiotics. Moreover, recent work reveals the existence of an undiscovered alternate route for bringing lipoproteins to the OM. Here, lipoprotein transport mechanisms, and the quality control systems that underpin them, is re-examined in context of their diversity. © 2018 WILEY Periodicals, Inc.

  8. Hiding in Plain Sight: Contaminated Ice Machines Are a Potential Source for Dissemination of Gram-Negative Bacteria and Candida Species in Healthcare Facilities.

    Science.gov (United States)

    Kanwar, Anubhav; Cadnum, Jennifer L; Xu, Dongyan; Jencson, Annette L; Donskey, Curtis J

    2018-03-01

    BACKGROUND Contaminated ice machines have been linked to transmission of pathogens in healthcare facilities. OBJECTIVE To determine the frequency and sites of contamination of ice machines in multiple healthcare facilities and to investigate potential mechanisms of microorganism dispersal from contaminated ice machines to patients. DESIGN Multicenter culture survey and simulation study. SETTING The study took place in 5 hospitals and 2 nursing homes in northeastern Ohio. METHODS We cultured multiple sites on ice machines from patient care areas. To investigate potential mechanisms of microbial dispersal from contaminated ice machines, we observed the use of ice machines and conducted simulations using a fluorescent tracer and cultures. RESULTS Samples from 64 ice machines in the 5 hospitals and 2 nursing homes (range, 3-16 per facility) were cultured. Gram-negative bacilli and/or Candida spp were recovered from 100% of drain pans, 52% of ice and/or water chutes, and 72% of drain-pan grilles. During the operation of ice machines, ice often fell through the grille, resulting in splattering, with dispersal of contaminated water from the drain pan to the drain-pan grille, cups, and the hands of those using the ice machine. Contamination of the inner surface of the ice chute resulted in contamination of ice cubes exiting the chute. CONCLUSIONS Our findings demonstrate that ice machines in healthcare facilities are often contaminated with gram-negative bacilli and Candida species, and provide a potential mechanism by which these organisms may be dispersed. Effective interventions are needed to reduce the risk of dissemination of pathogenic organisms from ice machines. Infect Control Hosp Epidemiol 2018;39:253-258.

  9. Ceftazidime/avibactam activity tested against Gram-negative bacteria isolated from bloodstream, pneumonia, intra-abdominal and urinary tract infections in US medical centres (2012).

    Science.gov (United States)

    Flamm, Robert K; Farrell, David J; Sader, Helio S; Jones, Ronald N

    2014-06-01

    The activity of ceftazidime/avibactam and comparator agents was monitored at 73 medical centres across all nine US census bureau regions during 2012. Bacterial isolates were collected from patients hospitalized with pneumonia, urinary tract infections (UTI), intra-abdominal infections (IAI) and bloodstream infections (BSI). The study protocol predetermined the target numbers of strains for each of the requested bacterial species that sites were to collect. Isolates were determined to be clinically relevant at the medical centre and only one isolate per patient episode was collected. There were 1466 Gram-negative isolates from BSI, 3245 from pneumonia patients, 501 from IAI and 2356 from UTI. Ceftazidime/avibactam was active against Enterobacteriaceae from each infection type. The MIC90 values for ceftazidime/avibactam against Enterobacteriaceae isolates from BSI, pneumonia patients, IAI or UTI were 0.25 mg/L. The extended-spectrum cephalosporin resistance rates for Escherichia coli were 8.5% (UTI), 10.4% (IAI), 12.7% (BSI) and 17.5% (pneumonia patients). The extended-spectrum cephalosporin resistance rates for Klebsiella spp. were 13.0% (UTI), 13.9% (BSI), 16.3% (IAI) and 19.3% (pneumonia patients). A total of 96.5% of the Pseudomonas aeruginosa isolates from BSI, 95.8% from pneumonia patients, 96.3% from IAI and 98.7% from UTI exhibited a ceftazidime/avibactam MIC of ≤8 mg/L (CLSI susceptible breakpoint for ceftazidime when tested alone against P. aeruginosa). Most tested agents showed limited activity against Acinetobacter baumannii, except for colistin. A total of 31.2% of A. baumannii displayed ceftazidime/avibactam MIC values of ≤8 mg/L. Ceftazidime/avibactam demonstrated potent broad-spectrum activity against Gram-negative pathogens collected in the USA during 2012 from BSI, pneumonia patients, IAI and UTI. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For

  10. Broad-Host-Range Expression Reveals Native and Host Regulatory Elements That Influence Heterologous Antibiotic Production in Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Jia Jia Zhang

    2017-09-01

    Full Text Available Heterologous expression has become a powerful tool for studying microbial biosynthetic gene clusters (BGCs. Here, we extend the transformation-associated recombination cloning and heterologous expression platform for microbial BGCs to include Gram-negative proteobacterial expression hosts. Using a broad-host-range expression platform, we test the implicit assumption that biosynthetic pathways are more successfully expressed in more closely related heterologous hosts. Cloning and expression of the violacein BGC from Pseudoalteromonas luteoviolacea 2ta16 revealed robust production in two proteobacterial hosts, Pseudomonas putida KT2440 and Agrobacterium tumefaciens LBA4404, but very little production of the antibiotic in various laboratory strains of Escherichia coli, despite their closer phylogenetic relationship. We identified a nonclustered LuxR-type quorum-sensing receptor from P. luteoviolacea 2ta16, PviR, that increases pathway transcription and violacein production in E. coli by ∼60-fold independently of acyl-homoserine lactone autoinducers. Although E. coli harbors the most similar homolog of PviR identified from all of the hosts tested, overexpression of various E. coli transcription factors did not result in a statistically significant increase in violacein production, while overexpression of two A. tumefaciens PviR homologs significantly increased production. Thus, this work not only introduces a new genetic platform for the heterologous expression of microbial BGCs, it also challenges the assumption that host phylogeny is an accurate predictor of host compatibility.

  11. Multi-functional characteristics of the Pseudomonas aeruginosa type III needle-tip protein, PcrV; comparison to orthologs in other gram negative bacteria

    Directory of Open Access Journals (Sweden)

    Hiromi eSato

    2011-07-01

    Full Text Available Pseudomonas aeruginosa possesses a type III secretion system (T3SS to intoxicate host cells and evade innate immunity. This virulence-related machinery consists of a molecular syringe and needle assembled on the bacterial surface, which allows delivery of T3 effector proteins into infected cells. To accomplish a one-step effector translocation, a tip protein is required at the top end of the T3 needle structure. Strains lacking expression of the functional tip protein fail to intoxicate host cells.P. aeruginosa encodes a T3S that is highly homologous to the proteins encoded by Yersinia species. The needle tip proteins of Yersinia, LcrV, and P. aeruginosa, PcrV, share 37% identity and 65% similarity. Other known tip proteins are AcrV (Aeromonas, IpaD (Shigella, SipD (Salmonella, BipD (Burkholderia, EspA (EPEC, EHEC, Bsp22 (Bordetella, with additional proteins identified from various Gram negative species, such as Vibrio and Bordetella. The tip proteins can serve as a protective antigen or may be critical for sensing host cells and evading innate immune responses. Recognition of the host microenvironment transcriptionally activates synthesis of T3SS components. The machinery appears to be mechanically controlled by the assemblage of specific junctions within the apparatus. These junctions include the tip and base of the T3 apparatus, the needle proteins and components within the bacterial cytoplasm. The tip proteins likely have chaperone functions for translocon proteins, allowing the proper assembly of translocation channels in the host membrane and completing vectorial delivery of effector proteins into the host cytoplasm. Multifunctional features of the needle-tip proteins appear to be intricately controlled. In this review, we highlight the functional aspects and complex controls of T3 needle-tip proteins with particular emphasis on PcrV and LcrV.

  12. Gram-negative and Gram-positive bacterial extracellular vesicles.

    Science.gov (United States)

    Kim, Ji Hyun; Lee, Jaewook; Park, Jaesung; Gho, Yong Song

    2015-04-01

    Like mammalian cells, Gram-negative and Gram-positive bacteria release nano-sized membrane vesicles into the extracellular environment either in a constitutive manner or in a regulated manner. These bacterial extracellular vesicles are spherical bilayered proteolipids enriched with bioactive proteins, lipids, nucleic acids, and virulence factors. Recent progress in this field supports the critical pathophysiological functions of these vesicles in both bacteria-bacteria and bacteria-host interactions. This review provides an overview of the current understanding on Gram-negative and Gram-positive bacterial extracellular vesicles, especially regarding the biogenesis, components, and functions in poly-species communities. We hope that this review will stimulate additional research in this emerging field of bacterial extracellular vesicles and contribute to the development of extracellular vesicle-based diagnostic tools and effective vaccines against pathogenic Gram-negative and Gram-positive bacteria. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Significance of postgrowth processing of ZnO nanostructures on antibacterial activity against gram-positive and gram-negative bacteria.

    Science.gov (United States)

    Mehmood, Shahid; Rehman, Malik A; Ismail, Hammad; Mirza, Bushra; Bhatti, Arshad S

    2015-01-01

    In this work, we highlighted the effect of surface modifications of one-dimensional (1D) ZnO nanostructures (NSs) grown by the vapor-solid mechanism on their antibacterial activity. Two sets of ZnO NSs were modified separately - one set was modified by annealing in an Ar environment, and the second set was modified in O2 plasma. Annealing in Ar below 800°C resulted in a compressed lattice, which was due to removal of Zn interstitials and increased O vacancies. Annealing above 1,000°C caused the formation of a new prominent phase, Zn2SiO4. Plasma oxidation of the ZnO NSs caused an expansion in the lattice due to the removal of O vacancies and incorporation of excess O. Photoluminescence (PL) spectroscopy was employed for the quantification of defects associated with Zn and O in the as-grown and processed ZnO NS. Two distinct bands were observed, one in the ultraviolet (UV) region, due to interband transitions, and other in the visible region, due to defects associated with Zn and O. PL confirmed the surface modification of ZnO NS, as substantial decrease in intensities of visible band was observed. Antibacterial activity of the modified ZnO NSs demonstrated that the surface modifications by Ar annealing limited the antibacterial characteristics of ZnO NS against Staphylococcus aureus. However, ZnO NSs annealed at 1,000°C or higher showed a remarkable antibacterial activity against Escherichia coli. O2 plasma-treated NS showed appreciable antibacterial activity against both E. coli and S. aureus. The minimum inhibition concentration was determined to be 0.5 mg/mL and 1 mg/mL for Ar-annealed and plasma-oxidized ZnO NS, respectively. It was thus proved that the O content at the surface of the ZnO NS was crucial to tune the antibacterial activity against both selected gram-negative (E. coli) and gram-positive (S. aureus) bacterial species.

  14. Effects of Gram-negative Bacteria, E.coli and Cold Exposure on Free Radicals Production, Lactate Dehydrogenase and Glutathione Peroxidase Activity in the Lungs of Rats, Rattus norvigicus

    International Nuclear Information System (INIS)

    AlSaid, A Haffor

    2007-01-01

    The purpose of this study was to explore the effects of LPS-gram negative bacteria and low ambient temperature on free radicals (FR) production, the activities of lactate dehydrogenase (LDH) and glutathione peroxidase (GPx) in the lungs of rats, Rattus norvigisu. Twenty four male rats, matched with age and weigh, were divided randomly into four groups namely control (C), Bacteria (B), cold temperature (T), and bacteria plus cold (BT). The T group was exposed to 10-12degree C ambient temperature for 3 days. Animals of the BT was injected LPS bacteria (IP, 500 micron g/kg) during the last five hour of cold exposure to 10-12 degree C for 3 days. In comparison with C group FR increased significantly (p<0.05) in the experimental groups, indicating high rate of reactive oxygen species (ROS) accumulation. The activity of LDH increased significantly (p<0.05) in the T and BT groups, which demonstrated that bacteria and exposure to cold are causes for cellular injury in the lungs. The synergetic effect of both bacteria and cold on LDH was more intense, as compared with the single effect. The activity of GPx increased significantly (p<0.05) in the B and BT, as compared with the C group. The results of the present study is the first worldwide report to demonstrate that both cold exposure and bacteria infection are mediated by elevation in FR generation. (author)

  15. Evaluation of Inhibitory and Lethal Effects of Aqueous, Ethanolic and Hydroalcoholic Extracts of Aerial Parts of Salvia chorassanica against Some Gram-negative and Gram-positive Bacteria in Vitro

    Directory of Open Access Journals (Sweden)

    Azam Mehraban

    2016-05-01

    Full Text Available Abstract Background and Objectives: Development of bacterial resistance to antibiotics has led to an increased tendency to development of new more effective and non-toxic antimicrobial compounds. In this study, the inhibitory and lethal effects of aqueous, ethanolic, and hydroalcoholic extracts of aerial parts of Salvia chorassanica were evaluated against Listeria monocytogenes, Bacillus cereus, Salmonella typhi, and Escherichia coli O:157. Methods: In this study, Kirby–Bauer disk diffusion method was used to evaluate antimicrobial activity. In this method, bacteria were cultivated as grass culture in Mueller Hinton Agar (MHA media. To determine the minimum inhibitory concentration and minimum bactericidal concentration, micro-dilution method with ELISA and addition of phenyl tetrazolium chloride reagent, were used. Data were analyzed using one-way ANOVA and Duncan’s test at the significance level of p<0.05. Results: The highest diameter of inhibition in agar diffusion method was related to hydroalcoholic extract of aerial parts of Salvia chorassanica against Gram-positive bacteria Bacillus cereus. The amount of calculated MIC of hydro-alcoholic extract for Gram-positive bacteria was 30mg/ml. This amount was the lowest among other measured MIC. Conclusion: Based on the results of this study, Gram-negative bacteria showed more resistance to different extracts of aerial parts of Salvia chorassanica as compared to Gram-positive bacteria, so that Salmonella typhi was found to be the most resistant bacterium among the tested bacteria.

  16. Effects of reducing beta-lactam antibiotic pressure on intestinal colonization of antibiotic-resistant gram-negative bacteria

    NARCIS (Netherlands)

    S. Nijssen (Saskia); A.C. Fluit (Ad); D.A.M.C. van de Vijver (David); J. Top (Janetta); R.J.L. Willems (Rob); M.J.M. Bonten (Marc)

    2010-01-01

    textabstractBackground: We determined the effects of two antibiotic policies (predominance of either β-lactam antibiotics or fluroquinolones) on acquisition with third-generation cephalosporin-resistant Enterobacteriaceae (CRE) and fluoroquinolone-resistant CRE (FCRE) in two ICUs, with monitoring of

  17. Distribution and Antimicrobial Susceptibility Pattern of Gram Negative Bacteria Causing Urinary Tract Infection (UTI and Detection New Delhi Metallo-beta-lactamase-1 (NDM-1 Producing Isolates in Ahwaz

    Directory of Open Access Journals (Sweden)

    Parviz Afrugh

    2016-04-01

    Full Text Available Background: Urinary tract infection (UTI is the commonest bacterial infectious disease in worldwide (especially in developing countries with a high rate of morbidity and financial cost. The management of UTI infections has been jeopardized by increase in immergence of antimicrobial drug resistance. Knowledge of the local bacterial etiology and susceptibility patterns is required to trace any change that might have occurred in time so that updated recommendation for optimal empirical therapy of UTI can be made. The aim of this investigation was distribution and antimicrobial susceptibility pattern of gram negative bacteria causing urinary tract infection (UTI and detection NDM-1 (new-delhi-metallo-beta-lactamase-1 producing isolates in Ahwaz. Materials and Methods: This cross-sectional study was done during a period of one year from April 2013 to March 2014. Clean catch midstream urine samples were collected from suspected patients to UTI. The isolates were identified based on morphological and biochemical testes. Culture was performed on routine microbiological media. Susceptibility testing was performed according CLSI (2013 guidelines. Detection of carbapenemase producing isolates was performed by modified hodge test (MHT. Metallo-beta-lactamase isolates were detected by imipenem-EDTA combined disc test (CDT. Results: In this study 708 gram negative organisms were isolated from urine samples. E.coli was the most common isolated bacteria (67% followed by Klebsiella spp. (26.5% and Enterobacter spp. (2.5%. In antibiotic susceptibility testing more than 90% of isolates were sensitive to tetracycline, ceftazidime, meropenem, amikacin, cefotaxime, imipenem, and cefepime. Isolates were more resistant to cephalothin (32%, co-trimoxazol (30.5%, and nalidixic acid (25%. Conclusion: In our results isolated organisms from outpatients showed very high sensitivity to common antibiotics. Continuous and regular monitoring of susceptibility pattern of

  18. Anticancer and antibacterial secondary metabolites from the endophytic fungus Penicillium sp. CAM64 against multi-drug resistant Gram-negative bacteria.

    Science.gov (United States)

    Jouda, Jean-Bosco; Tamokou, Jean-de-Dieu; Mbazoa, Céline Djama; Sarkar, Prodipta; Bag, Prasanta Kumar; Wandji, Jean

    2016-09-01

    The emergence of multiple-drug resistance bacteria has become a major threat and thus calls for an urgent need to search for new effective and safe anti-bacterial agents. This study aims to evaluate the anticancer and antibacterial activities of secondary metabolites from Penicillium sp., an endophytic fungus associated with leaves of Garcinia nobilis. The culture filtrate from the fermentation of Penicillium sp. was extracted and analyzed by liquid chromatography-mass spectrometry, and the major metabolites were isolated and identified by spectroscopic analyses and by comparison with published data. The antibacterial activity of the compounds was assessed by broth microdilution method while the anticancer activity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The fractionation of the crude extract afforded penialidin A-C (1-3), citromycetin (4), p-hydroxyphenylglyoxalaldoxime (5) and brefelfin A (6). All of the compounds tested here showed antibacterial activity (MIC = 0.50 - 128 µg/mL) against Gramnegative multi-drug resistance bacteria, Vibrio cholerae (causative agent of dreadful disease cholera) and Shigella flexneri (causative agent of shigellosis), as well as the significant anticancer activity (LC 50 = 0.88 - 9.21 µg/mL) against HeLa cells. The results obtained indicate that compounds 1-6 showed good antibacterial and anticancer activities with no toxicity to human red blood cells and normal Vero cells.

  19. Adhesion and inactivation of Gram-negative and Gram-positive bacteria on photoreactive TiO2/polymer and Ag-TiO2/polymer nanohybrid films

    Science.gov (United States)

    Tallósy, Szabolcs Péter; Janovák, László; Nagy, Elisabeth; Deák, Ágota; Juhász, Ádám; Csapó, Edit; Buzás, Norbert; Dékány, Imre

    2016-05-01

    The aim of this study was to develop photoreactive surface coatings, possessing antibacterial properties and can be activated under visible light illumination (λmax = 405 nm) using LED-light source. The photocatalytically active titanium dioxide (TiO2) was functionalized with silver nanoparticles (Ag NPs) and immobilized in polyacrylate based nanohybrid thin film in order to facilitate visible light activity (λAg/TiO2,max = 500 nm). First, the photocatalytic activity was modelled by following ethanol vapor degradation. The plasmonic functionalization resulted in 15% enhancement of the activity compared to pure TiO2. The photoreactive antimicrobial (5 log reduction of cfu in 2 h) surface coatings are able to inactivate clinically relevant pathogen strains (methicillin resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa) within short time (60-120 min) due to the formed and quantified reactive oxygen species (ROS). The existence of electrostatic interactions between the negatively charged bacteria (from -0.89 to -3.19 μeq/109 cfu) and positively charged photocatalyst particles (in the range of +0.38 and +12.3 meq/100 g) was also proven by charge titration measurements. The surface inactivation of the bacteria and the photocatalytic degradation of the cell wall component were also confirmed by fluorescence and transmission electron microscopic observations, respectively. According to the results an effective sterilizing system and prevention strategy can be developed and carried out against dangerous microorganisms in health care.

  20. Inactivation of Gram-Negative Bacteria by Low-Pressure RF Remote Plasma Excited in N2-O2 Mixture and SF6 Gases

    Directory of Open Access Journals (Sweden)

    Ayman Al-Mariri

    2013-12-01

    Full Text Available The role of low-pressure RF plasma in the inactivation of Escherichia coli O157, Klebsiella pneumoniae, Proteus mirabilis, and Enterobacter sakazakii using N2-O2 and SF6 gases was assessed. 1×109 colony-forming units (CFUs of each bacterial isolate were placed on three polymer foils. The effects of pressure, power, distance from the source, and exposure time to plasma gases were optimized. The best conditions to inactivate the four bacteria were a 91%N2-9%O2 mixture and a 30-minute exposure time. SF6 gas was more efficient for all the tested isolates in as much as the treatment time was reduced to only three minutes. Therefore, low-pressure plasma could be used to sterilize heat and/or moisture-sensitive medical instruments.

  1. Chemical constituents of Helichrysum italicum (Roth G. Don essential oil and their antimicrobial activity against Gram-positive and Gram-negative bacteria, filamentous fungi and Candida albicans

    Directory of Open Access Journals (Sweden)

    Bouzid Djihane

    2017-07-01

    Full Text Available The aerial parts of Helichrysum italicum (Roth G. Don were subjected to hydrodistillation to obtain essential oils which had been analyzed by gas chromatography and gas chromatography coupled with mass spectrometry and tested for antimicrobial activity against 12 bacteria, two yeasts and four fungi by agar diffusion method. The essential oil yielded 0.44% (v/w and 67 compounds accounting for 99.24% of the oil were identified with a high content of oxygenated sesquiterpenes (61.42%. The most oxygenated sesquiterpene compounds were α-Cedrene (13.61%, α-Curcumene (11.41%, Geranyl acetate (10.05%, Limonene (6.07%, Nerol (5.04%, Neryl acetate (4.91% and α-Pinene (3.78%. The antimicrobial activity of the essential oil was assayed by using the disk diffusion method on Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, Micrococcus luteus ATCC 4698, Klebsiella pneumonia ATCC 4352, Enterococcus cereus ATCC 2035, Bacillus cereus ATCC 10876, Staphylococcus epidermidis ATCC 12228, Bacillus subtilis ATCC 9372, Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATCC 49452, Proteus mirabilis ATCC 35659, Listeria monocytogenes ATCC 15313 and yeasts Candida albicans ATCC 10231, Saccharomyces cerevisiae ATCC 9763 and fungi, Fusarium solani var. coeruleum, Aspergillus niger, Alternaria alternata, Ascochyta rabiei. H. italicum inhibited the growth of all the tested microorganisms except three bacteria, E. coli ATCC 25922, K. pneumonia ATCC 4352 and L. monocytogenes ATCC 15313. The most sensitive bacterium was E. cereus ATCC 2035 with minimum inhibitory and bactericidal concentrations of 0.79 μg ml−1. A minimum fungistatic and fungicide concentration of 6.325 μg ml−1 and 12.65 μg ml−1 respectively was obtained with C. albicans ATCC 10231 and S. cerevisiae ATCC 9763. However the four fungi were more resistant with fungistatic minimum concentration ranging from 6.325 μg ml−1 to 50.6 μg ml−1 and a fungicide minimum

  2. A multidisciplinary intervention to reduce infections of ESBL- and AmpC-producing, gram-negative bacteria at a University Hospital.

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    Jenny Dahl Knudsen

    Full Text Available In response to a considerable increase in the infections caused by ESBL/AmpC-producing Klebsiella pneumonia in 2008, a multidisciplinary intervention, with a main focus on antimicrobial stewardship, was carried out at one university hospital. Four other hospitals were used as controls. Stringent guidelines for antimicrobial treatment and prophylaxis were disseminated throughout the intervention hospital; cephalosporins were restricted for prophylaxis use only, fluoroquinolones for empiric use in septic shock only, and carbapenems were selected for penicillin-allergic patients, infections due to ESBL/AmpC-producing and other resistant bacteria, in addition to their use in severe sepsis/septic shock. Piperacillin-tazobactam ± gentamicin was recommended for empiric treatments of most febrile conditions. The intervention also included education and guidance on infection control, as well as various other surveillances. Two year follow-up data on the incidence rates of patients with selected bacterial infections, outcomes, and antibiotic consumption were assessed, employing before-and-after analysis and segmented regression analysis of interrupted time series, using the other hospitals as controls. The intervention led to a sustained change in antimicrobial consumption, and the incidence of patients infected with ESBL-producing K. pneumoniae decreased significantly (p<0.001. The incidences of other hospital-associated infections also declined (p's<0.02, but piperacillin-tazobactam-resistant Pseudomonas aeruginosa and Enterococcus faecium infections increased (p's<0.033. In wards with high antimicrobial consumption, the patient gut carrier rate of ESBL-producing bacteria significantly decreased (p = 0.023. The unadjusted, all-cause 30-day mortality rates of K. pneumoniae and E. coli were unchanged over the four-year period, with similar results in all five hospitals. Although not statistically significant, the 30-day mortality rate of patients

  3. Strategies for the empirical management of infection in cancer patients with emphasis on the emergence of resistant gram-negative bacteria.

    Science.gov (United States)

    Klastersky, Jean; Georgala, Aspasia

    2014-12-01

    Combinations of antibiotics (namely penicillins and aminoglycosides) have been advocated in the 1970s for the empirical therapy of FN in cancer patients in order to take advantage of the possible synergism between these agents and to extend the potential antimicrobial spectrum of empirical therapy. Later, with the development of potent broad spectrum antibiotics, the need for combinations became less obvious as monotherapy with these new agents appeared as effective and less toxic than previously used combinations. However, today we are facing a major challenge through the emergence of multi-resistant microrganisms. With such bacteria, we might be coming back to the pre-antibiotic era when no active agents were available. This situation is due, in part, by the excessive use of antibiotics, namely as a prophylaxis for infection, and is complicated by the fact that very few new effective antibiotics are being developed by the pharmaceutical industry. Under these circumstances, it is likely that we will have to resort to "old timers" such as the polymyxins. It is also possible that combination therapy will come back in favor to take advantage of the synergism and extend the spectrum of coverage, just as it has been the case for the management of resistant tuberculosis. At the same time, the development of multidisciplinary antimicrobial stewardship is mandatory for efficient infection control and minimizing emergence of antimicrobial resistance. Copyright © 2014. Published by Elsevier Ireland Ltd.

  4. Extended-Spectrum β-Lactamase, AmpC, and MBL-Producing Gram-Negative Bacteria on Fresh Vegetables and Ready-to-Eat Salads Sold in Local Markets.

    Science.gov (United States)

    Iseppi, Ramona; de Niederhäusern, Simona; Bondi, Moreno; Messi, Patrizia; Sabia, Carla

    2018-02-16

    We investigated the occurrence of extended-spectrum β-lactamase (ESBL), AmpC, and carbapenemase-producing Gram-negative bacteria isolated from 160 samples of fresh vegetables (n = 80) and ready-to-eat (RTE) prepacked salads (n = 80). Phenotypic and genotypic analyses were carried out on the isolates in terms of the species present and relative resistance. Resistance to β-lactam antibiotics was found in only 44 (24 from fresh vegetables and 20 from RTE salads) of a total of 312 Gram-negative strains (14.1%). The prevalence of ESBL-producing strains from fresh vegetables was 83.3% (20/24) and 16.7% (4/24) for AmpC. Among the 20 bacterial isolates from RTE salads, 80% (16/20) were identified as ESBL-producing strains and the remaining 20% (4/20) as MBL-producing strains. PCR and sequencing confirmed the presence of bla SHV-12 , bla CTX-M-1 , bla CTX-M-15, bla RHAN -1 , bla ACC-1 , bla DHA-1 , bla VIM-1 , and bla IMP-1 . Seven different replicons were identified, where IncHI1, FIA, and I1 were the most representative types; when compared with the Inc types, isolates from fresh vegetables and RTE salads were similar. The location of genes on a conjugative plasmid was confirmed by positive results obtained with conjugation assays. Our study has demonstrated the occurrence and distribution of ESBL/AmpC and MBL strains in fresh vegetables and RTE salads in Italy and possible public health risks associated with consumption of these fresh products.

  5. Veillonella, Firmicutes: Microbes disguised as Gram negatives

    DEFF Research Database (Denmark)

    Vesth, Tammi Camilla; Ozen, Asli; Andersen, Sandra Christine

    2013-01-01

    related to Gram-negative species. Though the Negativicutes stain Gram-negative and possess two membranes, the genome and proteome analysis presented here confirm their place within the (mainly) Gram positive phylum of the Firmicutes. Further studies are required to unveil the evolutionary history...

  6. Sinus surgery postpones chronic gram-negative lung infection

    DEFF Research Database (Denmark)

    Alanin, M C; Aanaes, K; Høiby, N

    2016-01-01

    Background: In patients with cystic fibrosis (CF) the sinuses are a bacterial reservoir for Gram-negative bacteria (GNB). From the sinuses the GNB can repeatedly migrate to the lungs. In a one-year follow-up study, endoscopic sinus surgery (ESS) with adjuvant therapy reduced the frequency...

  7. Occurrence of unusual non-fermentative gram negative bacilli in ...

    African Journals Online (AJOL)

    Non-fermentative Gram-negative bacilli (NFGNB) other than Pseudomonas and Acinetobacter species have emerged as nosocomial pathogens. No much data is currently available concerning the occurrence of these types of bacteria in Zagazig University Hospitals (ZUHs). In this study, the occurrence as well as the ...

  8. Detection of Extended Spectrum Beta-Lactamases in Gram Negative ...

    African Journals Online (AJOL)

    Antimicrobial drug resistance seen among many gram-negative bacteria, especially those expressing the extended-spectrum β-lactamase (ESBL) enzymes that hydrolyze the expandedspectrum cephalosporins has been on the increase. This has compromised treatment options and thus a threat to the containment of ...

  9. Establishment of tolerance to commensal bacteria requires a complex microbiota and is accompanied by decreased intestinal chemokine expression

    DEFF Research Database (Denmark)

    Fink, Lisbeth Nielsen; Metzdorff, S. B.; Zeuthen, Louise

    2012-01-01

    Intricate regulation of tolerance to the intestinal commensal microbiota acquired at birth is critical. We hypothesized that epithelial cell tolerance toward early gram-positive and gram-negative colonizing bacteria is established immediately after birth, as has previously been shown for endotoxin...

  10. Third generation cephalosporin resistant Enterobacteriaceae and multidrug resistant gram-negative bacteria causing bacteremia in febrile neutropenia adult cancer patients in Lebanon, broad spectrum antibiotics use as a major risk factor, and correlation with poor prognosis

    Directory of Open Access Journals (Sweden)

    Rima eMoghnieh

    2015-02-01

    Full Text Available Bacteremia remains a major cause of life-threatening complications in patients receiving anticancer chemotherapy. The spectrum and susceptibility profiles of causative microorganisms differ with time and place. Data from Lebanon are scarce. We aim at evaluating the epidemiology of bacteremia in cancer patients in a university hospital in Lebanon, emphasizing antibiotic resistance and risk factors of multi-drug resistant organism (MDRO-associated bacteremia.This is a retrospective study of 75 episodes of bacteremia occurring in febrile neutropenic patients admitted to the hematology-oncology unit at Makassed General Hospital, Lebanon, from October 2009-January 2012.It corresponds to epidemiological data on bacteremia episodes in febrile neutropenic cancer patients including antimicrobial resistance and identification of risk factors associated with third generation cephalosporin resistance (3GCR and MDRO-associated bacteremia. Out of 75 bacteremias, 42.7% were gram-positive (GP, and 57.3% were gram-negative (GN. GP bacteremias were mostly due to methicillin-resistant coagulase negative staphylococci (28% of total bacteremias and 66% of GP bacteremias. Among the GN bacteremias, Escherichia coli (22.7% of total, 39.5% of GN organisms and Klebsiellapneumoniae(13.3% of total, 23.3% of GN organisms were the most important causative agents. GN bacteremia due to 3GC sensitive (3GCS bacteria represented 28% of total bacteremias, while 29% were due to 3GCR bacteria and 9% were due to carbapenem-resistant organisms. There was a significant correlation between bacteremia with MDRO and subsequent intubation, sepsis and mortality. Among potential risk factors, only broad spectrum antibiotic intake >4 days before bacteremia was found to be statistically significant for acquisition of 3GCR bacteria. Using carbapenems or piperacillin/ tazobactam>4 days before bacteremia was significantly associated with the emergence of MDRO (p value<0.05.

  11. Comparison of TiO2 and ZnO nanoparticles for photocatalytic degradation of methylene blue and the correlated inactivation of gram-positive and gram-negative bacteria

    International Nuclear Information System (INIS)

    Barnes, Robert J.; Molina, Rodrigo; Xu Jianbin; Dobson, Peter J.; Thompson, Ian P.

    2013-01-01

    Titanium dioxide (TiO 2 ) and zinc oxide (ZnO) nanoparticles are important photocatalysts and as such have been extensively studied for the removal of organic compounds from contaminated air and water and for microbial disinfection. Despite much research on the effect of TiO 2 and ZnO nanoparticles on different bacterial species, uncertainties remain about which bacteria are more sensitive to these compounds. Very few studies have directly compared the toxicity of ZnO to TiO 2 under both light and dark conditions. In addition, authors investigating the photocatalytic inactivation of TiO 2 and ZnO nanoparticles on bacteria have failed to investigate the reactive oxygen species (ROS) generation of the nanoparticles, making it difficult to correlate killing action with the generation of ROS. In this study, three types of metal nanoparticle (ZnO 2 ) have been characterised and ROS production assessed through the degradation of methylene blue (MB). The photocatalytic killing potential of three nanoparticle concentrations (0.01, 0.1 and 1 g/L) was then assessed on four representative bacteria: two gram-positive (S. aureus and B. subtilis) and two gram-negative (E. coli and P. aeruginosa). Results showed that out of the three nanoparticles tested, the TiO 2 nanoparticles generated more ROS than the ZnO nanoparticles, corresponding to a greater photocatalytic inactivation of three of the four species of bacteria examined. The MB decomposition results correlated well with the bacterial inactivation results with higher TiO 2 nanoparticle concentrations leading to greater ROS production and increased loss of cell viability. Although producing less ROS than the TiO 2 nanoparticles under ultraviolet light, the ZnO nanoparticles were toxic to two of the bacterial species even under dark conditions. In this study, no correlation between cell wall type and bacterial inactivation was observed for any of the nanoparticles tested although both gram-positive bacteria were sensitive to

  12. Comparison of TiO2 and ZnO nanoparticles for photocatalytic degradation of methylene blue and the correlated inactivation of gram-positive and gram-negative bacteria

    Science.gov (United States)

    Barnes, Robert J.; Molina, Rodrigo; Xu, Jianbin; Dobson, Peter J.; Thompson, Ian P.

    2013-02-01

    Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles are important photocatalysts and as such have been extensively studied for the removal of organic compounds from contaminated air and water and for microbial disinfection. Despite much research on the effect of TiO2 and ZnO nanoparticles on different bacterial species, uncertainties remain about which bacteria are more sensitive to these compounds. Very few studies have directly compared the toxicity of ZnO to TiO2 under both light and dark conditions. In addition, authors investigating the photocatalytic inactivation of TiO2 and ZnO nanoparticles on bacteria have failed to investigate the reactive oxygen species (ROS) generation of the nanoparticles, making it difficult to correlate killing action with the generation of ROS. In this study, three types of metal nanoparticle (ZnO killing potential of three nanoparticle concentrations (0.01, 0.1 and 1 g/L) was then assessed on four representative bacteria: two gram-positive ( S. aureus and B. subtilis) and two gram-negative ( E. coli and P. aeruginosa). Results showed that out of the three nanoparticles tested, the TiO2 nanoparticles generated more ROS than the ZnO nanoparticles, corresponding to a greater photocatalytic inactivation of three of the four species of bacteria examined. The MB decomposition results correlated well with the bacterial inactivation results with higher TiO2 nanoparticle concentrations leading to greater ROS production and increased loss of cell viability. Although producing less ROS than the TiO2 nanoparticles under ultraviolet light, the ZnO nanoparticles were toxic to two of the bacterial species even under dark conditions. In this study, no correlation between cell wall type and bacterial inactivation was observed for any of the nanoparticles tested although both gram-positive bacteria were sensitive to ROS production. P. aeruginosa cells were resistant to all types of treatment and highlight a potential limitation to the

  13. Carbapenem susceptibilities and non-susceptibility concordance to different carbapenems amongst clinically important Gram-negative bacteria isolated from intensive care units in Taiwan: results from the Surveillance of Multicentre Antimicrobial Resistance in Taiwan (SMART) in 2009.

    Science.gov (United States)

    Jean, Shio-Shin; Hsueh, Po-Ren; Lee, Wen-Sen; Yu, Kwok-Woon; Liao, Chun-Hsing; Chang, Feng-Yi; Ko, Wen-Chien; Wu, Jiunn-Jong; Chen, Yen-Hsu; Chen, Yao-Shen; Liu, Jien-Wei; Lu, Min-Chi; Liu, Cheng-Yi; Lam, Carlos; Chen, Ray-Jade

    2013-05-01

    To investigate the in vitro susceptibilities to various carbapenems amongst clinical Gram-negative bacteria isolated from patients in intensive care units of ten major teaching hospitals in Taiwan in 2009, a survey was conducted to determine the minimum inhibitory concentrations (MICs) of ertapenem, imipenem, meropenem and doripenem against isolates of Enterobacteriaceae (n = 594), Pseudomonas aeruginosa (n = 185), Acinetobacter baumannii (n = 192) and Burkholderia cepacia (n = 23) using the agar dilution method. Susceptibilities were determined according to 2009, 2011 and 2012 MIC breakpoints recommended by the CLSI as well as 2012 MIC breakpoints recommended by EUCAST. Based on CLSI 2012 criteria, the ertapenem susceptible rate was 93%, 81%, 68% and 92% for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae and Serratia marcescens, respectively. All Proteus mirabilis and Morganella morganii isolates were susceptible to ertapenem; however, 64% of P. mirabilis and all M. morganii isolates were non-susceptible to imipenem. Meropenem and doripenem had better activities than imipenem against ertapenem-non-susceptible Enterobacteriaceae isolates. E. coli, K. pneumoniae and E. cloacae with ertapenem MICs≥4 mg/L were synchronously not susceptible to imipenem, meropenem and doripenem. Imipenem susceptibility was 65% and 29% for P. aeruginosa and A. baumannii, respectively. Additionally, P. aeruginosa and A. baumannii isolates with imipenem MICs≥8 mg/L were also not susceptible to meropenem and doripenem. These data provide a better understanding of choosing appropriate carbapenem agents to treat infections caused by ertapenem-non-susceptible Enterobacteriaceae as well as P. aeruginosa and A. baumannii isolates with imipenem MICs≥4 mg/L. Copyright © 2013 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  14. Emerging quinolones resistant transfer genes among gram-negative bacteria, isolated from faeces of HIV/AIDS patients attending some Clinics and Hospitals in the City of Benin, Edo State, Nigeria

    Directory of Open Access Journals (Sweden)

    Enabulele IO

    2006-12-01

    Full Text Available A survey of 1431 gram-negative bacilli from June 2001 to September 2005 were obtained from the faeces of 920 HIV/AIDS patients attending some Clinics and Hospitals in Benin City, Nigeria, were screened for quinolones resistance gene. The HIV/AIDS patients CD4 cells range was ≤14/mm3 ≥800/mm3 of blood. Out of the 1431 isolates, 343 (23.9% were resistance to quinolones with a MIC ≥4μg/ml for norfloxacin, ciprofloxacin and pefloxacin while a MIC of ≥32 µg/ml for nalidixic acid. The screened isolates include Pseudomonas aeruginosa 64(18.7%, E coli 92(26.8%, Klebsiella pneumoniae 53(15.4%, Salmonella typhi 39(11.4%, Shigella dysenteriae 36(10.5%, Proteus mirabilis 34(9.9% and Serratia marcescens 25(7.3%. The average resistance of the isolates to the various quinolones ranged from 42.7% to 66.7%. Klebsiella were the most resistant isolates with a mean resistance of 66.7% while Proteus were the less resistant isolates with a mean resistance of 42.7%. Most isolates were resistant to Nalidixic acid followed by norfloxacin while the less resistant were to the pefloxacin. The frequency of qnr genes transfer to EJRifr as recipient ranged from 2 x 10-2 to 6 x 10-6 with an average of 2 plasmids per cell. The molecular weight of the plasmids ranged from <2.9kbp to <5.5 kbp. This indicated that plasmids allowed the movement of genetic materials including qnr resistant genes between bacteria species and genera in Benin City, Nigeria.

  15. Third generation cephalosporin resistant Enterobacteriaceae and multidrug resistant gram-negative bacteria causing bacteremia in febrile neutropenia adult cancer patients in Lebanon, broad spectrum antibiotics use as a major risk factor, and correlation with poor prognosis.

    Science.gov (United States)

    Moghnieh, Rima; Estaitieh, Nour; Mugharbil, Anas; Jisr, Tamima; Abdallah, Dania I; Ziade, Fouad; Sinno, Loubna; Ibrahim, Ahmad

    2015-01-01

    Bacteremia remains a major cause of life-threatening complications in patients receiving anticancer chemotherapy. The spectrum and susceptibility profiles of causative microorganisms differ with time and place. Data from Lebanon are scarce. We aim at evaluating the epidemiology of bacteremia in cancer patients in a university hospital in Lebanon, emphasizing antibiotic resistance and risk factors of multi-drug resistant organism (MDRO)-associated bacteremia. This is a retrospective study of 75 episodes of bacteremia occurring in febrile neutropenic patients admitted to the hematology-oncology unit at Makassed General Hospital, Lebanon, from October 2009-January 2012. It corresponds to epidemiological data on bacteremia episodes in febrile neutropenic cancer patients including antimicrobial resistance and identification of risk factors associated with third generation cephalosporin resistance (3GCR) and MDRO-associated bacteremia. Out of 75 bacteremias, 42.7% were gram-positive (GP), and 57.3% were gram-negative (GN). GP bacteremias were mostly due to methicillin-resistant coagulase negative staphylococci (28% of total bacteremias and 66% of GP bacteremias). Among the GN bacteremias, Escherichia coli (22.7% of total, 39.5% of GN organisms) and Klebsiella pneumoniae(13.3% of total, 23.3% of GN organisms) were the most important causative agents. GN bacteremia due to 3GC sensitive (3GCS) bacteria represented 28% of total bacteremias, while 29% were due to 3GCR bacteria and 9% were due to carbapenem-resistant organisms. There was a significant correlation between bacteremia with MDRO and subsequent intubation, sepsis and mortality. Among potential risk factors, only broad spectrum antibiotic intake >4 days before bacteremia was found to be statistically significant for acquisition of 3GCR bacteria. Using carbapenems or piperacillin/tazobactam>4 days before bacteremia was significantly associated with the emergence of MDRO (p < 0.05). Our findings have major

  16. Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions

    Science.gov (United States)

    Amachawadi, Raghavendra G.; Renter, David G.; Volkova, Victoriya V.

    2016-01-01

    Antimicrobial treatments result in the host’s enteric bacteria being exposed to the antimicrobials. Pharmacodynamic models can describe how this exposure affects the enteric bacteria and their antimicrobial resistance. The models utilize measurements of bacterial antimicrobial susceptibility traditionally obtained in vitro in aerobic conditions. However, in vivo enteric bacteria are exposed to antimicrobials in anaerobic conditions of the lower intestine. Some of enteric bacteria of food animals are potential foodborne pathogens, e.g., Gram-negative bacilli Escherichia coli and Salmonella enterica. These are facultative anaerobes; their physiology and growth rates change in anaerobic conditions. We hypothesized that their antimicrobial susceptibility also changes, and evaluated differences in the susceptibility in aerobic vs. anaerobic conditions of generic E. coli and Salmonella enterica of diverse serovars isolated from cattle feces. Susceptibility of an isolate was evaluated as its minimum inhibitory concentration (MIC) measured by E-Test® following 24 hours of adaptation to the conditions on Mueller-Hinton agar, and on a more complex tryptic soy agar with 5% sheep blood (BAP) media. We considered all major antimicrobial drug classes used in the U.S. to treat cattle: β-lactams (specifically, ampicillin and ceftriaxone E-Test®), aminoglycosides (gentamicin and kanamycin), fluoroquinolones (enrofloxacin), classical macrolides (erythromycin), azalides (azithromycin), sulfanomides (sulfamethoxazole/trimethoprim), and tetracyclines (tetracycline). Statistical analyses were conducted for the isolates (n≥30) interpreted as susceptible to the antimicrobials based on the clinical breakpoint interpretation for human infection. Bacterial susceptibility to every antimicrobial tested was statistically significantly different in anaerobic vs. aerobic conditions on both media, except for no difference in susceptibility to ceftriaxone on BAP agar. A satellite experiment

  17. IgA/IgM Responses to Gram-Negative Bacteria are not Associated with Perinatal Depression, but with Physio-Somatic Symptoms and Activation of the Tryptophan Catabolite Pathway at the End of Term and Postnatal Anxiety.

    Science.gov (United States)

    Roomruangwong, Chutima; Kanchanatawan, Buranee; Sirivichayakul, Sunee; Anderson, George; Carvalho, André F; Duleu, Sebastien; Geffard, Michel; Maes, Michael

    2017-04-07

    Evidence has implicated the translocation of commensal Gram-negative bacteria (Gram-B) due to leaky gut in the pathophysiology of depression and physio-somatic symptoms (e.g. fatigue, pain, irritable bowel syndrome, malaise, etc.). In addition, the leaky gut may contribute to immune-inflammatory activation and oxidative stress. This study investigated whether bacterial translocation is associated with perinatal depression and anxiety scores and with prenatal physio-somatic symptoms and immune-inflammatory biomarkers, including the tryptophan catabolite (TRYCAT) pathway. Data were collected in pregnant women at the end of term (T1) and 4-6 weeks after delivery (T2) as well as in non-pregnant controls. We examined the associations between serum IgM/IgA responses to Gram-B at the end of term and depression (Edinburgh Postnatal Depression Scale -EPDS) and anxiety (Spielberger's State Anxiety Inventory -STAI) symptoms. Levels of C-reactive protein, zinc, haptoglobin, hematocrit and IgA/IgM responses to 9 TRYCATs were also measured. No significant associations of the IgA/IgM responses to Gram-B with prenatal depression and anxiety were observed. Increased IgA/IgM responses to Gram-B predict higher levels of haptoglobin, hematocrit and TRYCATs, in particular quinolinic acid and the quinolinic acid / kynurenic acid ratio. IgA responses to Gram-B were significantly lowered in pregnant women compared to age-matched non-pregnant women, while IgM responses were significantly elevated in participants with alcohol consumption. Physio-somatic symptoms at the end of term were significantly associated with IgM responses to Klebsiella pneumonia. Postnatal anxiety was significantly predicted by IgA responses to Pseudomonas aeruginosa. In conclusion, our findings suggest that pregnancy may protect against bacterial translocation, while alcohol use may increase bacterial translocation. The results suggest that end of term mucosa-derived immune responses to Gram-B contribute to immune

  18. From Bench-Top to Bedside: A Prospective In Vitro Antibiotic Combination Testing (iACT) Service to Guide the Selection of Rationally Optimized Antimicrobial Combinations against Extensively Drug Resistant (XDR) Gram Negative Bacteria (GNB).

    Science.gov (United States)

    Cai, Yiying; Chua, Nathalie Grace; Lim, Tze-Peng; Teo, Jocelyn Qi-Min; Lee, Winnie; Kurup, Asok; Koh, Tse-Hsien; Tan, Thuan-Tong; Kwa, Andrea L

    2016-01-01

    Combination therapy is increasingly utilized against extensively-drug resistant (XDR) Gram negative bacteria (GNB). However, choosing a combination can be problematic as effective combinations are often strain-specific. An in vitro antibiotic combination testing (iACT) service, aimed to guide the selection of individualized and rationally optimized combination regimens within 48 hours, was developed. We described the role and feasibility of the iACT service in guiding individualized antibiotic combination selection in patients with XDR-GNB infections. A retrospective case review was performed in two Singapore hospitals from April 2009-June 2014. All patients with XDR-GNB and antibiotic regimen guided by iACT for clinical management were included. The feasibility and role of the prospective iACT service was evaluated. The following patient outcomes were described: (i) 30-day in-hospital all-cause and infection-related mortality, (ii) clinical response, and (iii) microbiological eradication in patients with bloodstream infections. From 2009-2014, the iACT service was requested by Infectious Disease physicians for 39 cases (20 P. aeruginosa, 13 A. baumannii and 6 K. pneumoniae). Bloodstream infection was the predominant infection (36%), followed by pneumonia (31%). All iACT recommendations were provided within 48h from request for the service. Prior to iACT-guided therapy, most cases were prescribed combination antibiotics empirically (90%). Changes in the empiric antibiotic regimens were recommended in 21 (54%) cases; in 14 (36%) cases, changes were recommended as the empiric regimens were found to be non-bactericidal in vitro. In 7 (18%) cases, the number of antibiotics used in combination empirically was reduced by the iACT service. Overall, low 30-day infection-related mortality (15%) and high clinical response (82%) were observed. Microbiological eradication was observed in 79% of all bloodstream infections. The iACT service can be feasibly employed to guide the

  19. Gram-negative folliculitis. A rare problem or is it underdiagnosed? Case report and literature review

    Directory of Open Access Journals (Sweden)

    Sierra-Téllez Daniela, Ponce-Olivera Rosa María, Tirado-Sánchez Andrés

    2011-07-01

    Full Text Available AbstractGram-negative folliculitis may be the result of prolonged antibacterial treatments in patients with acne and rosacea. It is caused by alteration of facial skin flora and the nasal mucous, a decrease of Gram-positive bacteria and a proliferation of Gram-negative bacteria (for example Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Klebsiella sp. and Proteus mirabilis. It should be considered in patients with acne who have not had a clinical improvement after 3-6 months of treatment with tetracyclines. The disease is underestimated, probably because bacteriological studies are rarely requested and the increased use of oral isotretinoin for acne management. One of the most effective treatments for Gram-negative folliculitis is oral isotretinoin (0.5-1 mg / kg / day for 4-5 months. We report the case of Gram negative folliculitis successfully treated with oral isotretinoin.

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

    Directory of Open Access Journals (Sweden)

    Tonny Loho

    2016-05-01

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

  1. [Diagnostic and therapeutic management of Gram-negative infections].

    Science.gov (United States)

    Bassetti, Matteo; Repetto, Ernestina

    2008-04-01

    Among Gram negative bacteria, Pseudomonas aeruginosa, the extended spectrum beta-lactamases (ESBL)-producing strains, Acinetobacter spp, in particular the multiresistant Acinetobacter baumannii, and Stenotrophomonas maltophilia are the most implicated micrororganisms in the ever more increasing problem of bacterial resistance. Possible solutions have to be searched, on one hand, in the use of new drugs but, on the other hand, in the re-evaluation of those already available drugs, possibly considering a new role for old drugs such as colistine and fosfomycin. Concerning ESBL-producing strains, the most recent data provided by EARSS report, in Italy, an incidence rate of 10-25 percent. The insurgence of an infection sustained by an ESBL+ve strain is strictly related to some well known risk factors, like the hospital stay itself, the disease severity, the length of stay in ICU, intubation and mechanical ventilation, catheterization, urinary or artery, and the past exposure to antibiotics. The raise in ESBL producing strains is closely related to the increasing use of cephalosporins. In the setting of a Gram negative infection, the combination therapy guarantees a higher coverage by reducing insurgence of possible resistance mechanisms, possibly resulting synergistic, and allowing a de-escalation therapy, although to this latter other problems, such as tolerability, costs and compliance, can be related. Another basic aspect to take into account of, in order to achieve the maximal efficacy of the antibiotic treatment, is the right dosage. In the idea to look for the best approach for the antibiotic treatment of a severe infection in a hospital setting, when a Gram negative aetiology is implicated, it can be possibly presumed that the right way consists in avoiding inappropriate antibiotic therapies, making therapeutic choices based on guidelines resulted from local epidemiological data, initiating the therapy promptly, avoiding excessive use of antibiotics, possibly

  2. The friendly bacteria within us Commensal bacteria of the intestine ...

    Indian Academy of Sciences (India)

    The friendly bacteria within us Commensal bacteria of the intestine: Roles in health and disease B.S. Ramakrishna Professor & Head Gastroenterology & Hepatology Christian Medical College Vellore · Slide 2 · Intestinal bacteria: the hidden organ · Slide 4 · Slide 5 · The normal bacterial flora prevents GI disease · Slide 7.

  3. Prior colonization is associated with increased risk of antibiotic-resistant Gram-negative bacteremia in cancer patients.

    Science.gov (United States)

    Hess, Aaron S; Kleinberg, Michael; Sorkin, John D; Netzer, Giora; Johnson, Jennifer K; Shardell, Michelle; Thom, Kerri A; Harris, Anthony D; Roghmann, Mary-Claire

    2014-05-01

    We hypothesized that prior colonization with antibiotic-resistant Gram-negative bacteria is associated with increased risk of subsequent antibiotic-resistant Gram-negative bacteremia among cancer patients. We performed a matched case-control study. Cases were cancer patients with a blood culture positive for antibiotic-resistant Gram-negative bacteria. Controls were cancer patients with a blood culture not positive for antibiotic-resistant Gram-negative bacteria. Prior colonization was defined as any antibiotic-resistant Gram-negative bacteria in surveillance or non-sterile-site cultures obtained 2-365 days before the bacteremia. Thirty-two (37%) of 86 cases and 27 (8%) of 323 matched controls were previously colonized by any antibiotic-resistant Gram-negative bacteria. Prior colonization was strongly associated with antibiotic-resistant Gram-negative bacteremia (odds ratio [OR] 7.2, 95% confidence interval [CI] 3.5-14.7) after controlling for recent treatment with piperacillin-tazobactam (OR 2.5, 95% CI 1.3-4.8). In these patients with suspected bacteremia, prior cultures may predict increased risk of antibiotic-resistant Gram-negative bacteremia. Copyright © 2014 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    Loho, Tonny; Dharmayanti, Anti

    2015-04-01

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

  5. Evaluation of the Staphylococcus aureus class C nonspecific acid phosphatase (SapS) as a reporter for gene expression and protein secretion in gram-negative and gram-positive bacteria.

    Science.gov (United States)

    du Plessis, Erika; Theron, Jacques; Berger, Eldie; Louw, Maureen

    2007-11-01

    A phosphatase secreted by Staphylococcus aureus strain 154 has previously been characterized and classified as a new member of the bacterial class C family of nonspecific acid phosphatases. As the acid phosphatase activity can be easily detected with a cost-effective plate screen assay, quantitatively measured by a simple enzyme assay, and detected by zymography, its potential use as a reporter system was investigated. The S. aureus acid phosphatase (sapS) gene has been cloned and expressed from its own regulatory sequences in Escherichia coli, Bacillus subtilis, and Bacillus halodurans. Transcriptional and translational fusions of the sapS gene with selected heterologous promoters and signal sequences were constructed and expressed in all three of the host strains. From the range of promoters evaluated, the strongest promoter for heterologous protein production in each of the host strains was identified, i.e., the E. coli lacZ promoter in E. coli, the B. halodurans alkaline protease promoter in B. subtilis, and the B. halodurans sigma(D) promoter in B. halodurans. This is the first report on the development of a class C acid phosphatase gene as a reporter gene with the advantage of being able to function in both gram-positive and gram-negative host strains.

  6. The gram-negative bacterial periplasm: Size matters.

    Directory of Open Access Journals (Sweden)

    Samuel I Miller

    2018-01-01

    Full Text Available Gram-negative bacteria are surrounded by two membrane bilayers separated by a space termed the periplasm. The periplasm is a multipurpose compartment separate from the cytoplasm whose distinct reducing environment allows more efficient and diverse mechanisms of protein oxidation, folding, and quality control. The periplasm also contains structural elements and important environmental sensing modules, and it allows complex nanomachines to span the cell envelope. Recent work indicates that the size or intermembrane distance of the periplasm is controlled by periplasmic lipoproteins that anchor the outer membrane to the periplasmic peptidoglycan polymer. This periplasm intermembrane distance is critical for sensing outer membrane damage and dictates length of the flagellar periplasmic rotor, which controls motility. These exciting results resolve longstanding debates about whether the periplasmic distance has a biological function and raise the possibility that the mechanisms for maintenance of periplasmic size could be exploited for antibiotic development.

  7. Marine Compounds with Therapeutic Potential in Gram-Negative Sepsis

    Directory of Open Access Journals (Sweden)

    Irina Yermak

    2013-06-01

    Full Text Available This paper concerns the potential use of compounds, including lipid A, chitosan, and carrageenan, from marine sources as agents for treating endotoxemic complications from Gram-negative infections, such as sepsis and endotoxic shock. Lipid A, which can be isolated from various species of marine bacteria, is a potential antagonist of bacterial endotoxins (lipopolysaccharide (LPSs. Chitosan is a widespread marine polysaccharide that is derived from chitin, the major component of crustacean shells. The potential of chitosan as an LPS-binding and endotoxin-neutralizing agent is also examined in this paper, including a discussion on the generation of hydrophobic chitosan derivatives to increase the binding affinity of chitosan to LPS. In addition, the ability of carrageenan, which is the polysaccharide of red alga, to decrease the toxicity of LPS is discussed. We also review data obtained using animal models that demonstrate the potency of carrageenan and chitosan as antiendotoxin agents.

  8. In vitro antibacterial activity of AZD0914, a new spiropyrimidinetrione DNA gyrase/topoisomerase inhibitor with potent activity against Gram-positive, fastidious Gram-Negative, and atypical bacteria.

    Science.gov (United States)

    Huband, Michael D; Bradford, Patricia A; Otterson, Linda G; Basarab, Gregory S; Kutschke, Amy C; Giacobbe, Robert A; Patey, Sara A; Alm, Richard A; Johnstone, Michele R; Potter, Marie E; Miller, Paul F; Mueller, John P

    2015-01-01

    AZD0914 is a new spiropyrimidinetrione bacterial DNA gyrase/topoisomerase inhibitor with potent in vitro antibacterial activity against key Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae), fastidious Gram-negative (Haemophilus influenzae and Neisseria gonorrhoeae), atypical (Legionella pneumophila), and anaerobic (Clostridium difficile) bacterial species, including isolates with known resistance to fluoroquinolones. AZD0914 works via inhibition of DNA biosynthesis and accumulation of double-strand cleavages; this mechanism of inhibition differs from those of other marketed antibacterial compounds. AZD0914 stabilizes and arrests the cleaved covalent complex of gyrase with double-strand broken DNA under permissive conditions and thus blocks religation of the double-strand cleaved DNA to form fused circular DNA. Whereas this mechanism is similar to that seen with fluoroquinolones, it is mechanistically distinct. AZD0914 exhibited low frequencies of spontaneous resistance in S. aureus, and if mutants were obtained, the mutations mapped to gyrB. Additionally, no cross-resistance was observed for AZD0914 against recent bacterial clinical isolates demonstrating resistance to fluoroquinolones or other drug classes, including macrolides, β-lactams, glycopeptides, and oxazolidinones. AZD0914 was bactericidal in both minimum bactericidal concentration and in vitro time-kill studies. In in vitro checkerboard/synergy testing with 17 comparator antibacterials, only additivity/indifference was observed. The potent in vitro antibacterial activity (including activity against fluoroquinolone-resistant isolates), low frequency of resistance, lack of cross-resistance, and bactericidal activity of AZD0914 support its continued development. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  9. The friendly bacteria within us Commensal bacteria of the intestine ...

    Indian Academy of Sciences (India)

    Short chain fatty acids (SCFA) are main source of energy for colonic epithelial cells · SCFA – role in colonic disease · SCFA prevent mucosal inflammation · Immunoregulation by gut bacteria · Balance of bacterial species in the gut · Immunosensory detection of intestinal bacteria · Pathogenic bacteria release interleukin-8 ...

  10. In vitro susceptibility of gram-negative bacterial isolates to chlorhexidine gluconate.

    Science.gov (United States)

    Mengistu, Y; Erge, W; Bellete, B

    1999-05-01

    To investigate the susceptibility of clinical isolates of gram-negative bacteria to chlorhexidine gluconate. Prospective laboratory study. Tikur Anbessa Hospital, Addis Ababa, Ethiopia. Clinical specimens from 443 hospital patients. Significant number of gram negative bacteria were not inhibited by chlorhexidine gluconate (0.02-0.05%) used for antisepsis. Four hundred and forty three strains of gram-negative bacteria were isolated from Tikur Anbessa Hospital patients. Escherichia coli (31.6%) and Klebsiella pneumoniae (23%) were the most frequently isolated bacteria followed by Proteus species (13.3%), Pseudomonas species (9.2%), and Citrobacter species (6.1%). Each organism was tested to chlorhexidine gluconate (CHG), minimum inhibitory concentration (MIC) ranging from 0.0001% to 1%w/v. All Salmonella species and E. coli were inhibited by CHG, MIC or = 0.1%). Our results showed that a significant number of the gram-negative bacterial isolates were not inhibited by CHG at the concentration used for disinfection of wounds or instruments (MIC 0.02-0.05% w/v). It is therefore important to select appropriate concentration of this disinfectant and rationally use it for disinfection and hospital hygiene. Continuing follow up and surveillance is also needed to detect resistant bacteria to chlorhexidine or other disinfectants in time.

  11. In-vitro activity of solithromycin against anaerobic bacteria from the normal intestinal microbiota.

    Science.gov (United States)

    Weintraub, Andrej; Rashid, Mamun-Ur; Nord, Carl Erik

    2016-12-01

    Solithromycin is a novel fluoroketolide with high activity against bacteria associated with community-acquired respiratory tract infections as well as gonorrhea. However, data on the activity of solithromycin against anaerobic bacteria from the normal intestinal microbiota are scarce. In this study, 1024 Gram-positive and Gram-negative anaerobic isolates from the normal intestinal microbiota were analyzed for in-vitro susceptibility against solithromycin and compared to azithromycin, amoxicillin/clavulanic acid, ceftriaxone, metronidazole and levofloxacin by determining the minimum inhibitory concentration (MIC). Solithromycin was active against Bifidobacteria (MIC 50 , 0.008 mg/L) and Lactobacilli (MIC 50 , 0.008 mg/L). The MIC 50 for Clostridia, Bacteroides, Prevotella and Veillonella were 0.5, 0.5, 0.125 and 0.016 mg/L, respectively. Gram-positive anaerobes were more susceptible to solithromycin as compared to the other antimicrobials tested. The activity of solithromycin against Gram-negative anaerobes was equal or higher as compared to other tested agents. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Adhesion and inactivation of Gram-negative and Gram-positive bacteria on photoreactive TiO{sub 2}/polymer and Ag–TiO{sub 2}/polymer nanohybrid films

    Energy Technology Data Exchange (ETDEWEB)

    Tallósy, Szabolcs Péter [Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, H-6725 Szeged, Semmelweis u. 6 (Hungary); Department of Physical Chemistry and Materials Sciences, University of Szeged, H-6720 Szeged, Aradi v.t.1 (Hungary); Janovák, László [Department of Physical Chemistry and Materials Sciences, University of Szeged, H-6720 Szeged, Aradi v.t.1 (Hungary); Nagy, Elisabeth [Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, H-6725 Szeged, Semmelweis u. 6 (Hungary); Deák, Ágota [Department of Physical Chemistry and Materials Sciences, University of Szeged, H-6720 Szeged, Aradi v.t.1 (Hungary); Juhász, Ádám; Csapó, Edit [MTA-SZTE Supramolecular and Nanostructured Materials Research Group, Department of Medical Chemistry, Faculty of Medicine, H-6720 Szeged, Dóm tér 8 (Hungary); Buzás, Norbert [Department of Health Economics, Faculty of Medicine, University of Szeged, H-6720 Szeged, Szőkefalvi-Nagy Béla u. 6 (Hungary); Dékány, Imre, E-mail: i.dekany@chem.u-szeged.hu [MTA-SZTE Supramolecular and Nanostructured Materials Research Group, Department of Medical Chemistry, Faculty of Medicine, H-6720 Szeged, Dóm tér 8 (Hungary)

    2016-05-15

    Highlights: • Surface reactivity of TiO{sub 2} and Ag–TiO{sub 2} nanohybrid films were tested by photooxidation. • Photocatalyst–bacteria interactions were defined by surface charge determination. • Higher surface charge induces stronger adhesion between the bacteria and the NPs. • Inactivation of GR+/GR− bacteria by hydroxyl radicals depends on cell wall structure. • The cell wall degradation of bacteria was proven with TEM and fluorescence studies - Abstract: The aim of this study was to develop photoreactive surface coatings, possessing antibacterial properties and can be activated under visible light illumination (λ{sub max} = 405 nm) using LED-light source. The photocatalytically active titanium dioxide (TiO{sub 2}) was functionalized with silver nanoparticles (Ag NPs) and immobilized in polyacrylate based nanohybrid thin film in order to facilitate visible light activity (λ{sub Ag/TiO2,max} = 500 nm). First, the photocatalytic activity was modelled by following ethanol vapor degradation. The plasmonic functionalization resulted in 15% enhancement of the activity compared to pure TiO{sub 2}. The photoreactive antimicrobial (5 log reduction of cfu in 2 h) surface coatings are able to inactivate clinically relevant pathogen strains (methicillin resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa) within short time (60–120 min) due to the formed and quantified reactive oxygen species (ROS). The existence of electrostatic interactions between the negatively charged bacteria (from −0.89 to −3.19 μeq/10{sup 9} cfu) and positively charged photocatalyst particles (in the range of +0.38 and +12.3 meq/100 g) was also proven by charge titration measurements. The surface inactivation of the bacteria and the photocatalytic degradation of the cell wall component were also confirmed by fluorescence and transmission electron microscopic observations, respectively. According to the results an effective sterilizing system and

  13. Fermentative bacteria from estuarine mud : phylogenetic position of Acidaminobacter hydrogenoformans and description of a new type of Gram-negative, propionigenic bacterium as Propionibacter pelophilus gen, nov., sp nov.

    NARCIS (Netherlands)

    Meijer, WG; Nienhuis-Kuiper, ME; Hansen, TA

    The phylogenetic positions of two strains of fermentative bacteria that had been isolated from the highest positive tubes inoculated with serial dilutions of estuarine mud in agar media with either glutamate or aspartate as substrate were determined by comparative sequence analysis of their 16S rRNA

  14. Coexpression of ESBL, Amp C and MBL in gram negative bacilli

    OpenAIRE

    Ruturaj M. Kolhapure; Ashwin Kumar; HRV Rajkumar

    2015-01-01

    Background: Resistant bacteria are emerging worldwide as a threat to the favourable outcome of common infections in community and hospital settings. Extended Spectrum Beta-Lactamases (ESBLs), AmpC beta lactamases and Metallo-beta Lactamases (MBL) are the three important mechanism of resistance to beta lactam drugs in the bacteria. The objective of the study was to screen gram negative isolates for co-expression of extended spectrum beta-lactamase, Amp C beta-lactamase and Metallo beta-lactama...

  15. A Gestalt approach to Gram-negative entry.

    Science.gov (United States)

    Silver, Lynn L

    2016-12-15

    A major obstacle confronting the discovery and development of new antibacterial agents to combat resistant Gram-negative (GN) organisms is the lack of a rational process for endowing compounds with properties that allow (or promote) entry into the bacterial cytoplasm. The major permeability difference between GN and Gram-positive (GP) bacteria is the GN outer membrane (OM) which is a permeability barrier itself and potentiates efflux pumps that expel compounds. Based on the fact that OM-permeable and efflux-deleted GNs are sensitive to many anti-GP drugs, recent efforts to approach the GN entry problem have focused on ways of avoiding efflux and transiting or compromising the OM, with the tacit assumption that this could allow entry of compounds into the GN cytoplasm. But bypassing the OM and efflux obstacles does not take into account the additional requirement of penetrating the cytoplasmic membrane (CM) whose sieving properties appear to be orthogonal to that of the OM. That is, tailoring compounds to transit the OM may well compromise their ability to enter the cytoplasm. Thus, a Gestalt approach to understanding the chemical requirements for GN entry seems a useful adjunct. This might consist of characterizing compounds which reach the cytoplasm, grouping (or binning) by routes of entry and formulating chemical 'rules' for those bins. This will require acquisition of data on large numbers of compounds, using non-activity-dependent methods of measuring accumulation in the cytoplasm. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. [Characteristics of epidemiology and antimicrobial resistance of gram-negative bacterial bloodstream infections in children].

    Science.gov (United States)

    Dong, L; Zhang, X Y; Li, C C; Li, Z; Xia, Y Q

    2017-09-02

    Objective: To study the epidemiology and antimicrobial resistance of Gram-negative bacterial bloodstream infections in children, and to guide the choice of antimicrobials and the control of nosocomial infection. Method: Clinical data, bacteriology and antimicrobial susceptibility test results were collected retrospectively in hospitalized children who were diagnosed with gram-negative bacterial bloodstream infections in Yuying Children's Hospital of Wenzhou Medical University from January, 2010 to December, 2015. Result: A total of 399 cases (253 male and 146 female) were identified. The age ranged from 16 hours to 16 years (median age 10.1 months). The majority of cases were collected from division of neonatology ( n =261, 65.4%), followed by 31 cases (7.8%) from pediatric intensive care unit and 29 cases (7.3%) from Gastroenterology Department; 275 cases (68.9%) had underlying diseases, mainly including preterm birth( n =172), neonatal respiratory distress syndrome( n =67) and newborn asphyxia( n =53). Eighty cases had received invasive procedures and 20 had surgical operation; 149 cases (37.3%) were community-acquired and 250 cases (62.7%) were hospital acquired. Fifty cases had complications, among those, 40 cases had septic shock, 32 cases had multiple organ dysfunction syndrome and 7 cases had disseminated intravascular coagulation; 288 cases were cured, 48 improved, 17 gave up treatment and discharged, and 46 died; totally 408 strains were isolated from 399 children, including Enterobacteriaceae (346, 84.8%), non-fermentative Gram-negative bacteria (49, 12.0%) and other gram-negative bacteria (13, 3.2%). The resistance rates of Escherichia coli ( n =175) and Klebsiella pneumoniae ( n =106) to carbapenems, β-lactams enzyme and its inhibitors, amikacin and cefoxitin were all lower than 10%. Totally 245 multi-drug resistant strains (60.1%) were isolated, including 225 strains of Enterobacteriaceae and 18 strains of non-fermentative Gram-negative bacteria ( P

  17. Pulmonary infiltrates during community acquired Gram-negative bacteremia

    DEFF Research Database (Denmark)

    Fjeldsøe-Nielsen, Hans; Gjeraa, Kirsten; Berthelsen, Birgitte G

    2013-01-01

    The primary aim of this study was to describe the frequency of pulmonary infiltrates on chest X-ray (CXR) during community acquired Gram-negative bacteremia at a single centre in Denmark.......The primary aim of this study was to describe the frequency of pulmonary infiltrates on chest X-ray (CXR) during community acquired Gram-negative bacteremia at a single centre in Denmark....

  18. Appraising contemporary strategies to combat multidrug resistant gram-negative bacterial infections--proceedings and data from the Gram-Negative Resistance Summit.

    Science.gov (United States)

    Kollef, Marin H; Golan, Yoav; Micek, Scott T; Shorr, Andrew F; Restrepo, Marcos I

    2011-09-01

    The emerging problem of antibiotic resistance, especially among Gram-negative bacteria (GNB), has become a serious threat to global public health. Very few new antibacterial classes with activity against antibiotic-resistant GNB have been brought to market. Renewed and growing attention to the development of novel compounds targeting antibiotic-resistant GNB, as well as a better understanding of strategies aimed at preventing the spread of resistant bacterial strains and preserving the efficacy of existing antibiotic agents, has occurred. The Gram-Negative Resistance Summit convened national opinion leaders for the purpose of analyzing current literature, epidemiologic trends, clinical trial data, therapeutic options, and treatment guidelines related to the management of antibiotic-resistant GNB infections. After an in-depth analysis, the Summit investigators were surveyed with regard to 4 clinical practice statements. The results then were compared with the same survey completed by 138 infectious disease and critical care physicians and are the basis of this article.

  19. Variations in the Produce-Associated Microbiota and the Occurrence Frequency of Extended-Spectrum Beta-Lactamase Gram-Negative Bacteria Result in Different Level of Ingestion Risks

    KAUST Repository

    Bokhari, Osama

    2016-04-01

    A monitoring effort that spanned across one and a half years was conducted to examine three types of produce-associated microbiota. Produce type was determined to be the predominant factor affecting the microbial communities. Other significant factors that resulted in differences in the microbial populations were the origin and sampling date. Specifically, produce-associated microbiota among lettuce and tomatoes clustered based on the sampling period. Through molecular and cultivation-based approaches, sporadic presence of extended spectrum beta-lactamase (ESBL)-positive Klebsiella pneumoniae and Acinetobacter baumannii was detected on lettuce and cucumbers during certain periods of sampling. Quantitative microbial risk assessment denoted varying levels of ingestion risks associated with different types of produce. In particular, the risks arising from ESBL-positive K. pneumoniae in the lettuce were higher than the acceptable annual risk of 10-4. Commonly used approaches to clean and wash the produce were insufficient in removing majority of the produce-associated microbiota. More invasive cleaning approaches or thorough cooking of the produce would be required to mitigate the associated risks. Most of the current reports of ESBL-positive bacterial isolates were identified in nosocomial environment. However, the carriage of such drug-resistant bacteria in food that is consumed daily

  20. Testing of the bactericidal action of products based on the "hydronic" technology ("informed glass") on ATCC strains of pathogenic Gram-positive and Gram-negative bacteria and yeasts (Staphylococcus aureus, Escherichia coli, and Candida albicans).

    Science.gov (United States)

    Racz, Aleksandar; Cipriŝ, Josip

    2010-04-01

    Scientific experiments were conducted with drinking water kept in "ordinary, everyday-use" glasses (drinking tumblers) and the so-called "informed" glasses (drinking tumblers), a patent-protected product supposed to have an effect on the "structure, vitality and memory of water," for which the manufacturer claims to have a wide range of positive effects on the health of patients with chronic medical problems, especially a "revitalizing" effect on water and the body (blue informed glass), additional metabolic effects such as facilitating weight loss (green informed glass), and a stress-relieving action (red informed glass). According to the claims of the patent owner, a Slovenian inventor Vili Poznik, by the use of the "orgone methodology," various transcendental, vitalizing information is purportedly coded and inscribed into the glass; this action is additionally enforced by the addition of the "magic life" symbol--a specially designed energy condenser which, together with the selected information, is permanently introduced into the liquid contained in the glass. The process of selection and transfer of information is a production secret known only to the inventors of the original "hydronic technology" for the discovery of which they have been awarded numerous prizes at innovation fairs, among others, a gold medal and a Crystal Globe at INPEX XVI exhibition in Pittsburgh, PA, in 2000. The aim of this research was to test the claims for informed glasses with respect to the bacteriocidal actions that have been claimed for these products. Given that the manufacturer attributes to the products produced by the "hydronic" technology--besides the effects on organoleptic properties of the drinking water consumed (which are subjective and liable to suggestion)--a broad bactericidal action against bacteria, yeasts, and molds but does not state a single scientific proof, the efficacy and bactericidal action of the products based on the hydronic technology were tested using

  1. Colonization of the oropharynx with Gram-negative bacilli in children with severe protein-calorie malnutrition.

    Science.gov (United States)

    Gilman, R H; Brown, K H; Gilman, J B; Gaffar, A; Alamgir, S M; Kibriya, A K; Sack, R B

    1982-08-01

    Oral pharyngeal isolation of Gram-negative bacteria was compared in four groups of Bengali children; acutely ill, severely malnourished outpatients swabbed on hospital admission; ill but less severely malnourished outpatients from the same area as the malnourished children; orphans also less severely malnourished but not acutely ill; and well controls drawn from a priviledged socioeconomic group. The expected weight for height percentage (National Center Health Statistics/Center for Disease Control median) of the four groups was respectively 67, 91, 97, and 97%. Isolation of Gram-negative bacteria from 74 of 87 (85%) severely malnourished children was significantly greater (p less than 0.01) compared to 43 of 113 (38%) outpatients, to 20 of 93 (22%) orphans, and to five of 51 (10%) controls. A total of 71 malnourished children under 5 yr of age (90%) had higher rates of Gram-negative throat colonization than did 16 older children (63%) (p less than 0.01). Thus there was an increased rate of Gram-negative colonization in severely malnourished children especially among the younger age group. In the subset of ill children, Gram-negative pharyngeal colonization was significantly associated inversely with nutritional indices and age. The high rate of such carriage may be partly responsible for the increased susceptibility of Gram-negative infection demonstrated in these children.

  2. Curative Treatment of Severe Gram-Negative Bacterial Infections by a New Class of Antibiotics Targeting LpxC

    Directory of Open Access Journals (Sweden)

    Nadine Lemaître

    2017-07-01

    Full Text Available The infectious diseases caused by multidrug-resistant bacteria pose serious threats to humankind. It has been suggested that an antibiotic targeting LpxC of the lipid A biosynthetic pathway in Gram-negative bacteria is a promising strategy for curing Gram-negative bacterial infections. However, experimental proof of this concept is lacking. Here, we describe our discovery and characterization of a biphenylacetylene-based inhibitor of LpxC, an essential enzyme in the biosynthesis of the lipid A component of the outer membrane of Gram-negative bacteria. The compound LPC-069 has no known adverse effects in mice and is effective in vitro against a broad panel of Gram-negative clinical isolates, including several multiresistant and extremely drug-resistant strains involved in nosocomial infections. Furthermore, LPC-069 is curative in a murine model of one of the most severe human diseases, bubonic plague, which is caused by the Gram-negative bacterium Yersinia pestis. Our results demonstrate the safety and efficacy of LpxC inhibitors as a new class of antibiotic against fatal infections caused by extremely virulent pathogens. The present findings also highlight the potential of LpxC inhibitors for clinical development as therapeutics for infections caused by multidrug-resistant bacteria.

  3. Direct common gram-negative bacterial identification from positive blood culture bottles by SELDI-TOF MS.

    Science.gov (United States)

    Xiao, Daiwen; Yang, Yongchang; Jiang, Wei; Zhang, Hangfeng; Liu, Hua; Yu, Hua; Xie, Chunbao; Zhong, Min; Chen, Liang; Huang, Wenfang

    2014-10-01

    A protein database was constructed and validated with identification rate over 90% for the 4 most common Gram-negative bacteria on agar plates. By protein masses comparison, 120 bacteria of the 4 species from blood culture bottles were identified. The concordance was high (Kappa=0.906) between our method and conventional approach. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Host susceptibility to gram-negative pneumonia after lung contusion.

    Science.gov (United States)

    Dolgachev, Vladislav A; Yu, Bi; Reinke, Julia M; Raghavendran, Krishnan; Hemmila, Mark R

    2012-03-01

    Lung contusion (LC) induces inflammation with high local concentrations of proinflammatory mediators stimulating chemotaxis and activation of neutrophils. LC is also a risk factor for development of pneumonia; however, the reason for this increased susceptibility is not clearly identified. We hypothesize that LC creates acute changes in the host pulmonary innate immune system that leads to vulnerability from a "second" hit bacterial infection. Female C57Bl/6 mice underwent LC injury at time -6 hours. At 0 hours, these mice were inoculated intratracheally with 1,000 colony forming unit (CFU) of Klebsiella pneumoniae (LC+Pneu) or vehicle (LC). Control animals underwent a sham LC injury followed by pneumonia (Sham+Pneu). Bronchoalveolar lavage (BAL) fluid and lung tissue specimens were collected. Lung bacteria levels were quantified by serial dilution, plating, and counting CFUs. Cytokine levels were assayed by ELISA. Cell type identification and quantification was performed using flow cytometry. Survival at 72 hours was markedly different for the LC, Sham+Pneu, and LC+Pneu groups (100%, 80%, 20%, p Pneu vs. LC+Pneu). LC+Pneu animals had decreased pulmonary bacterial clearance at 24 hours compared with the Sham+Pneu group (4 × 10(7) vs. 8 × 10(6) CFUs, p Pneu mice compared with the Sham+Pneu group at 24 hours. Conversely, the Sham+Pneu mice had increased levels of macrophage inflammatory protein-2, total cells, macrophages, and neutrophils in BAL compared with the LC+Pneu group at 24 hours. LC+Pneu animals demonstrated changes in macrophage apoptosis and necrosis in BAL samples obtained 2 hours after induction of pneumonia when compared with the Sham+Pneu group. Both Sham+Pneu and LC+Pneu animals demonstrated an increase in the level of IL-10 in BAL fluid compared with LC animals. Acute inflammation after LC acts to modulate the presence of inflammatory cells necessary to combat gram-negative bacteria. This results in decreased bacterial clearance and increased

  5. Prevalence of Gram-negative Pathogens and their antimicrobial ...

    African Journals Online (AJOL)

    The present study was conducted to find out the prevalence and spectrum of Gram negative pathogens causing bacterial meningitis and their antimicrobial susceptibility pattern in a tertiary care hospital. The cerebrospinal fluid (CSF) (3-5 ml) was collected from 638 admitted children clinically suspected of septic meningitis.

  6. Quinolones resistance and R-plasmids of some gram negative ...

    African Journals Online (AJOL)

    The isolated gram-negative enteric bacilli consist of Escherichia coli (22), Klebsiella species (65), Proteus species (20), Salmonella typhi (2), Pseudomonas aeruginosa (39) and Pseudomonas species (18). Among the antimicrobial agents tested, high resistance was found with ofloxacin 44.0%, followed by pefloxacin 30.1% ...

  7. Curative Treatment of Severe Gram-Negative Bacterial Infections by a New Class of Antibiotics Targeting LpxC

    Energy Technology Data Exchange (ETDEWEB)

    Lemaître, Nadine; Liang, Xiaofei; Najeeb, Javaria; Lee, Chul-Jin; Titecat, Marie; Leteurtre, Emmanuelle; Simonet, Michel; Toone, Eric J.; Zhou, Pei; Sebbane, Florent; Nacy, Carol A.

    2017-07-25

    ABSTRACT

    The infectious diseases caused by multidrug-resistant bacteria pose serious threats to humankind. It has been suggested that an antibiotic targeting LpxC of the lipid A biosynthetic pathway in Gram-negative bacteria is a promising strategy for curing Gram-negative bacterial infections. However, experimental proof of this concept is lacking. Here, we describe our discovery and characterization of a biphenylacetylene-based inhibitor of LpxC, an essential enzyme in the biosynthesis of the lipid A component of the outer membrane of Gram-negative bacteria. The compound LPC-069 has no known adverse effects in mice and is effectivein vitroagainst a broad panel of Gram-negative clinical isolates, including several multiresistant and extremely drug-resistant strains involved in nosocomial infections. Furthermore, LPC-069 is curative in a murine model of one of the most severe human diseases, bubonic plague, which is caused by the Gram-negative bacteriumYersinia pestis. Our results demonstrate the safety and efficacy of LpxC inhibitors as a new class of antibiotic against fatal infections caused by extremely virulent pathogens. The present findings also highlight the potential of LpxC inhibitors for clinical development as therapeutics for infections caused by multidrug-resistant bacteria.

    IMPORTANCEThe rapid spread of antimicrobial resistance among Gram-negative bacilli highlights the urgent need for new antibiotics. Here, we describe a new class of antibiotics lacking cross-resistance with conventional antibiotics. The compounds inhibit LpxC, a key enzyme in the lipid A biosynthetic pathway in Gram-negative bacteria, and are activein vitroagainst a broad panel of clinical isolates of Gram-negative bacilli involved in nosocomial and community infections. The present study also constitutes the first demonstration of the curative treatment of bubonic plague by a novel, broad

  8. Community-acquired multidrug-resistant Gram-negative bacterial infective endocarditis.

    Science.gov (United States)

    Naha, Sowjanya; Naha, Kushal; Acharya, Vasudev; Hande, H Manjunath; Vivek, G

    2014-08-05

    We describe two cases of bacterial endocarditis secondary to multidrug-resistant Gram-negative organisms. In both cases, the diagnosis was made in accordance with the modified Duke's criteria and confirmed by histopathological analysis. Furthermore, in both instances there were no identifiable sources of bacteraemia and no history of contact with hospital or other medical services prior to the onset of symptoms. The patients were managed in similar fashion with prolonged broad-spectrum antibiotic therapy and surgical intervention and made complete recoveries. These cases highlight Gram-negative organisms as potential agents for endocarditis, as well as expose the dissemination of such multidrug-resistant bacteria into the community. The application of an integrated medical and surgical approach and therapeutic dilemmas encountered in managing these cases are described. 2014 BMJ Publishing Group Ltd.

  9. Transmission dynamics of gram-negative bacterial pathogens in the anesthesia work area.

    Science.gov (United States)

    Loftus, Randy W; Brown, Jeremiah R; Patel, Hetal M; Koff, Matthew D; Jensen, Jens T; Reddy, Sundara; Ruoff, Kathryn L; Heard, Stephen O; Dodds, Thomas M; Beach, Michael L; Yeager, Mark P

    2015-04-01

    Gram-negative organisms are a major health care concern with increasing prevalence of infection and community spread. Our primary aim was to characterize the transmission dynamics of frequently encountered gram-negative bacteria in the anesthesia work area environment (AWE). Our secondary aim was to examine links between these transmission events and 30-day postoperative health care-associated infections (HCAIs). Gram-negative isolates obtained from the AWE (patient nasopharynx and axilla, anesthesia provider hands, and the adjustable pressure-limiting valve and agent dial of the anesthesia machine) at 3 major academic medical centers were identified as possible intraoperative bacterial transmission events by class of pathogen, temporal association, and phenotypic analysis (analytical profile indexing). The top 5 frequently encountered genera were subjected to antibiotic disk diffusion sensitivity to identify epidemiologically related transmission events. Complete multivariable logistic regression analysis and binomial tests of proportion were then used to examine the relative contributions of reservoirs of origin and within- and between-case modes of transmission, respectively, to epidemiologically related transmission events. Analyses were conducted with and without the inclusion of duplicate transmission events of the same genera occurring in a given study unit (first and second case of the day in each operating room observed) to examine the potential effect of statistical dependency. Transmitted isolates were compared by pulsed-field gel electrophoresis to disease-causing bacteria for 30-day postoperative HCAIs. The top 5 frequently encountered gram-negative genera included Acinetobacter, Pseudomonas, Brevundimonas, Enterobacter, and Moraxella that together accounted for 81% (767/945) of possible transmission events. For all isolates, 22% (167/767) of possible transmission events were identified by antibiotic susceptibility patterns as epidemiologically related

  10. Gram-Negative Infections in Adult Intensive Care Units of Latin America and the Caribbean

    Directory of Open Access Journals (Sweden)

    Carlos M. Luna

    2014-01-01

    Full Text Available This review summarizes recent epidemiology of Gram-negative infections in selected countries from Latin American and Caribbean adult intensive care units (ICUs. A systematic search of the biomedical literature (PubMed was performed to identify articles published over the last decade. Where appropriate, data also were collected from the reference list of published articles, health departments of specific countries, and registries. Independent cohort data from all countries (Argentina, Brazil, Chile, Colombia, Cuba, Mexico, Trinidad and Tobago, and Venezuela signified a high rate of ICU infections (prevalence: Argentina, 24%; Brazil, 57%. Gram-negative pathogens, predominantly Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli, accounted for >50% of ICU infections, which were often complicated by the presence of multidrug-resistant strains and clonal outbreaks. Empirical use of antimicrobial agents was identified as a strong risk factor for resistance development and excessive mortality. Infection control strategies utilizing hygiene measures and antimicrobial stewardship programs reduced the rate of device-associated infections. To mitigate the poor health outcomes associated with infections by multidrug-resistant Gram-negative bacteria, urgent focus must be placed on infection control strategies and local surveillance programs.

  11. Viruses and Gram-negative bacilli dominate the etiology of community-acquired pneumonia in Indonesia, a cohort study

    Directory of Open Access Journals (Sweden)

    Helmia Farida

    2015-09-01

    Conclusions: Viruses and Gram-negative bacilli are dominant causes of CAP in this region, more so than S. pneumoniae. Most of the bacteria have wild type susceptibility to antimicrobial agents. Patients with severe disease and those with unknown etiology have a higher mortality risk.

  12. Lifesaving pericardiocentesis due to purulent pericarditis with growth of Gram-negative rods in an immune-competent Inuit male

    DEFF Research Database (Denmark)

    Simonÿ, Carl Frederik Brandt; Malham, Mikkel; Kanstrup, Jacob

    2014-01-01

    Polymicrobial Gram-negative pericarditis is a rare entity in the immune-competent patient, and purulent pericarditis due to bacteria complicated by tamponade is a life-threatening condition with high mortality rates. A prompt diagnosis and treatment is, as in this case, lifesaving and facilitated...

  13. BacPP: a web-based tool for Gram-negative bacterial promoter prediction.

    Science.gov (United States)

    de Avila E Silva, S; Notari, D L; Neis, F A; Ribeiro, H G; Echeverrigaray, S

    2016-04-04

    Bacterial Promoter Prediction (BacPP) is a tool used to predict given sequences as promoters of Gram-negative bacteria according to the σ factor that recognizes it. The first version of BacPP was implemented in Python language in a desktop version without a friendly interface. For this reason, a web version of BacPP is now available with the purpose of improving its usability and availability. The present paper describes the implementation of the web version of this tool, focusing on its software architecture and user functionalities. The software is available at www.bacpp.bioinfoucs.com/home.

  14. Paracoccus marcusii sp. nov., an orange gram-negative coccus.

    Science.gov (United States)

    Harker, M; Hirschberg, J; Oren, A

    1998-04-01

    Phenotypic, chemotaxonomic and 16S rDNA sequence analysis of an orange Gram-negative coccus that appeared as a contaminant on a nutrient agar plate delineated a new species of the genus Paracoccus. Phenotypic features of the strain that differ from all or most of the previously described Paracoccus species include its bright orange colour, caused by the synthesis of large amounts of carotenoids (mainly astaxanthin), and its inability to use nitrate as an electron acceptor in respiration. The name Paracoccus marcusii is proposed for this organism. The type strain is DSM 11574T.

  15. [Metabolism of mangiferin by human intestinal bacteria in vitro].

    Science.gov (United States)

    Huang, Huixue; Tan, Zhenyuan; Deng, Jiagang; Liang, Qiuyun; Nong, Yumei; Song, Nianmei

    2011-02-01

    To study the metabolism of mangiferin by human intestinal bacteria in vitro. Human intestinal bacteria and mangiferin were incubated under anaerobic conditions in vitro. The metabolite was separated and purified by D101 macroporous resin column and preparation high performance liquid chromatography, and its structure was identified by MS and NMR. After 12 h incubation with human intestinal bacteria, the content of mangiferin metabolite reached the maximum, and it was determined as 1, 3, 6, 7-tetrahydroxyxanthen by MS and NMR. Mangiferin can be metabolized in vitro by human intestinal bacteria into its aglycone (1, 3, 6, 7-tetrahydroxyxanthen).

  16. Membrane-active macromolecules resensitize NDM-1 gram-negative clinical isolates to tetracycline antibiotics.

    Directory of Open Access Journals (Sweden)

    Divakara S S M Uppu

    Full Text Available Gram-negative 'superbugs' such as New Delhi metallo-beta-lactamase-1 (blaNDM-1 producing pathogens have become world's major public health threats. Development of molecular strategies that can rehabilitate the 'old antibiotics' and halt the antibiotic resistance is a promising approach to target them. We report membrane-active macromolecules (MAMs that restore the antibacterial efficacy (enhancement by >80-1250 fold of tetracycline antibiotics towards blaNDM-1 Klebsiella pneumonia and blaNDM-1 Escherichia coli clinical isolates. Organismic studies showed that bacteria had an increased and faster uptake of tetracycline in the presence of MAMs which is attributed to the mechanism of re-sensitization. Moreover, bacteria did not develop resistance to MAMs and MAMs stalled the development of bacterial resistance to tetracycline. MAMs displayed membrane-active properties such as dissipation of membrane potential and membrane-permeabilization that enabled higher uptake of tetracycline in bacteria. In-vivo toxicity studies displayed good safety profiles and preliminary in-vivo antibacterial efficacy studies showed that mice treated with MAMs in combination with antibiotics had significantly decreased bacterial burden compared to the untreated mice. This report of re-instating the efficacy of the antibiotics towards blaNDM-1 pathogens using membrane-active molecules advocates their potential for synergistic co-delivery of antibiotics to combat Gram-negative superbugs.

  17. Correction: Membrane-active macromolecules resensitize NDM-1 gram-negative clinical isolates to tetracycline antibiotics.

    Directory of Open Access Journals (Sweden)

    Divakara S S M Uppu

    Full Text Available Gram-negative 'superbugs' such as New Delhi metallo-beta-lactamase-1 (blaNDM-1 producing pathogens have become world's major public health threats. Development of molecular strategies that can rehabilitate the 'old antibiotics' and halt the antibiotic resistance is a promising approach to target them. We report membrane-active macromolecules (MAMsthat restore the antibacterial efficacy (enhancement by >80-1250 fold of tetracycline antibiotics towards blaNDM-1 Klebsiella pneumonia and blaNDM-1 Escherichia coli clinical isolates.Organismic studies showed that bacteria had an increased and faster uptake of tetracyclinein the presence of MAMs which is attributed to the mechanism of re-sensitization. Moreover,bacteria did not develop resistance to MAMs and MAMs stalled the development of bacterial resistance to tetracycline. MAMs displayed membrane-active properties such as dissipation of membrane potential and membrane-permeabilization that enabled higher uptake of tetracycline in bacteria. In-vivo toxicity studies displayed good safety profiles and preliminary in-vivo antibacterial efficacy studies showed that mice treated with MAMs in combination with antibiotics had significantly decreased bacterial burden compared to the untreated mice. This report of re-instating the efficacy of the antibiotics towards blaNDM-1 pathogens using membrane-active molecules advocates their potential for synergistic co-delivery of antibiotics to combat Gram-negative superbugs.

  18. Inhaled Antibiotics for Gram-Negative Respiratory Infections

    Science.gov (United States)

    Fraidenburg, Dustin R.; Scardina, Tonya

    2016-01-01

    SUMMARY Gram-negative organisms comprise a large portion of the pathogens responsible for lower respiratory tract infections, especially those that are nosocomially acquired, and the rate of antibiotic resistance among these organisms continues to rise. Systemically administered antibiotics used to treat these infections often have poor penetration into the lung parenchyma and narrow therapeutic windows between efficacy and toxicity. The use of inhaled antibiotics allows for maximization of target site concentrations and optimization of pharmacokinetic/pharmacodynamic indices while minimizing systemic exposure and toxicity. This review is a comprehensive discussion of formulation and drug delivery aspects, in vitro and microbiological considerations, pharmacokinetics, and clinical outcomes with inhaled antibiotics as they apply to disease states other than cystic fibrosis. In reviewing the literature surrounding the use of inhaled antibiotics, we also highlight the complexities related to this route of administration and the shortcomings in the available evidence. The lack of novel anti-Gram-negative antibiotics in the developmental pipeline will encourage the innovative use of our existing agents, and the inhaled route is one that deserves to be further studied and adopted in the clinical arena. PMID:27226088

  19. Clinical impact of delayed catheter removal for patients with central-venous-catheter-related Gram-negative bacteraemia.

    Science.gov (United States)

    Lee, Y-M; Moon, C; Kim, Y J; Lee, H J; Lee, M S; Park, K-H

    2018-01-10

    Gram-negative bacteria are increasingly the cause of catheter-related bloodstream infection (CRBSI), and the prevalence of multi-drug-resistant strains is rising rapidly. This study evaluated the impact of delayed central venous catheter (CVC) removal on clinical outcomes in patients with Gram-negative CRBSI. Between January 2007 and December 2016, patients with Gram-negative bacteraemia and CVC placement, from two tertiary care hospitals, were included retrospectively. Cases with CVC removal more than three days after onset of bacteraemia or without CVC removal were classified as having delayed CVC removal. In total, 112 patients were included. Of these, 78 had CRBSI (43 definite and 35 probable) and 34 had Gram-negative bacteraemia from another source (non-CRBSI). Enterobacteriaceae were less common pathogens in patients with CRBSI than in patients with non-CRBSI (11.5% vs 41.3%; P0.99). Delayed CVC removal [odds ratio (OR) 6.8], multi-drug-resistant (MDR) Gram-negative bacteraemia (OR 6.3) and chronic renal failure (OR 11.1) were associated with 30-day mortality in patients with CRBSI. The protective effect of early CVC removal on mortality was evident in the MDR group (48.3% vs 18.2%; P=0.03), but not in the non-MDR group (11.1% vs 0%; P=0.43). CVCs should be removed early to improve clinical outcomes in patients with Gram-negative CRBSI, especially in settings where MDR isolates are prevalent. Copyright © 2018 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  20. Detection of Extended Spectrum Beta-Lactamases Among Gram Negative Bacilli Recovered from Cattle Feces In Benin City, Nigeria

    Directory of Open Access Journals (Sweden)

    Helen Oroboghae OGEFERE

    2017-06-01

    Full Text Available This study was carried out to determine the prevalence of extended spectrum beta-lactamase (ESBL among Gram negative bacteria isolated from cattle feces in Benin City, Nigeria. A total of 250 Gram negative bacteria isolates were recovered from cattle feces and were processed microbiologically using standard techniques. Emergent colonies were identified and antibacterial susceptibility tests were determined using Kirby-Bauer disk diffusion method. All bacterial isolates were screened for the presence of ESBL using the double-disc synergy method. A total of 37 (14.8% isolates were positive for ESBL, with 33 (13.2% indicated by ceftazidime, while only 4 (1.6% were indicated by both ceftazidime and cefotaxime (P < 0.0001. Of the Gram negative bacterial isolates recovered, Salmonella species was the most prevalent ESBL-producer with 55.0% prevalence (P = 0.0092, while no isolate of Pseudomonas aeruginosa produced ESBL. ESBL-positive isolates showed poor susceptibility to the tested antibacterial agents in comparison with non-ESBL-producers and imipenem was the most active antibiotic. The prevalence of ESBL among Gram negative bacilli recovered from cattle feces was 14.8%. The study advises prudent use of antibiotics in the treatment of cattle and harps on improved hygiene in managing cattle, as they are potential reservoirs of ESBL-producing organisms.

  1. Prevalence of intestinal parasites and bacteria among food handlers ...

    African Journals Online (AJOL)

    No intestinal parasites were detected from fingernail contents. Forty six (23%) stool specimens were positive for intestinal para¬sites. Giardia lamblia 18 (9%) was most frequent among the 10 different types of detected intestinal parasites followed by Entamoeba histolytica 9 (4.5%). No pathogenic bacteria were detected in ...

  2. Engineered Endolysin-Based “Artilysins” To Combat Multidrug-Resistant Gram-Negative Pathogens

    Science.gov (United States)

    Briers, Yves; Walmagh, Maarten; Van Puyenbroeck, Victor; Cornelissen, Anneleen; Cenens, William; Aertsen, Abram; Oliveira, Hugo; Azeredo, Joana; Verween, Gunther; Pirnay, Jean-Paul; Miller, Stefan; Volckaert, Guido

    2014-01-01

    ABSTRACT The global threat to public health posed by emerging multidrug-resistant bacteria in the past few years necessitates the development of novel approaches to combat bacterial infections. Endolysins encoded by bacterial viruses (or phages) represent one promising avenue of investigation. These enzyme-based antibacterials efficiently kill Gram-positive bacteria upon contact by specific cell wall hydrolysis. However, a major hurdle in their exploitation as antibacterials against Gram-negative pathogens is the impermeable lipopolysaccharide layer surrounding their cell wall. Therefore, we developed and optimized an approach to engineer these enzymes as outer membrane-penetrating endolysins (Artilysins), rendering them highly bactericidal against Gram-negative pathogens, including Pseudomonas aeruginosa and Acinetobacter baumannii. Artilysins combining a polycationic nonapeptide and a modular endolysin are able to kill these (multidrug-resistant) strains in vitro with a 4 to 5 log reduction within 30 min. We show that the activity of Artilysins can be further enhanced by the presence of a linker of increasing length between the peptide and endolysin or by a combination of both polycationic and hydrophobic/amphipathic peptides. Time-lapse microscopy confirmed the mode of action of polycationic Artilysins, showing that they pass the outer membrane to degrade the peptidoglycan with subsequent cell lysis. Artilysins are effective in vitro (human keratinocytes) and in vivo (Caenorhabditis elegans). PMID:24987094

  3. Inhaled antibiotics for gram-negative respiratory infections.

    Science.gov (United States)

    Hudson, Ryan; Olson Blair, Brooke

    2011-10-01

    Several disease states create conditions that lead to opportunistic Gram-negative respiratory infections. Inhalation is the most direct and, until recently, underutilized means of antimicrobial drug targeting for respiratory tract infections. All approved antimicrobial agents for administration by inhalation are indicated for Pseudomonas aeruginosa infections in patients with cystic fibrosis. These inhaled therapies have directly contributed to a significant reduction in exacerbations and hospitalizations in this patient population over the last few decades. The relentless adaptation of pathogenic organisms to current treatment options demands that the pharmaceutical industry continue designing next-generation antimicrobial agents over 70 years after they were first introduced. Recent technological advances in inhalation devices and drug formulation techniques have broadened the scope of antimicrobial structural classes that can be investigated by inhalation; however, there is an urgent need to discover novel compounds with improved resistance profiles relative to those drugs that are already marketed.

  4. Pulmonary and systemic inflammatory responses in rabbits with gram-negative pneumonia.

    Science.gov (United States)

    Fox-Dewhurst, R; Alberts, M K; Kajikawa, O; Caldwell, E; Johnson, M C; Skerrett, S J; Goodman, R B; Ruzinski, J T; Wong, V A; Chi, E Y; Martin, T R

    1997-06-01

    The major goals of this study were to define the relationships between intrapulmonary and systemic inflammatory responses in animals with gram-negative pneumonia. We treated rabbits with intrapulmonary Escherichia coli (1 x 10(7) to 1 x 10(10) cfu/ml), and then measured physiologic, cellular, and molecular events in the lungs and systemic circulation for 24 h. The treatment protocols resulted in groups of animals that mimicked the stages of the septic inflammatory response in humans. Animals treated with low inocula had systemic changes consistent with systemic inflammatory response syndrome and cleared the bacteria and inflammatory products from the lungs. Animals treated with high inocula failed to clear bacteria from the lungs, had severe intrapulmonary inflammatory responses, and developed septic shock. Intrapulmonary leukocyte recruitment was directly related to the size of the bacterial inoculum, but lung protein accumulation was not. Tumor neurosis factor-alpha (TNF-alpha), interleukin-8 (IL-8), and GRO were detectable in lung lavage fluid at 4 h and declined by 24 h in animals that cleared intrapulmonary E. coli. In contrast, lavage TNF-alpha, IL-8, and GRO increased over 24 h in animals that failed to clear intrapulmonary bacteria. MCP-1 increased between 4 h and 24 h in the lungs of all of the animals as the histologic response evolved from neutrophilic to mononuclear cell predominance. Thus, the intensity of systemic inflammatory and physiologic responses to intrapulmonary gram-negative infection depends on the inoculum size and whether the bacteria are cleared from or proliferate in the lungs. The results provide experimental support for the recently proposed classification of septic responses in humans.

  5. Resistant gram-negative bacilli and antibiotic consumption in zarqa, jordan

    International Nuclear Information System (INIS)

    Bataineh, H.A.; Alrashed, K.M.

    2007-01-01

    To investigate the prevalence of antibiotic resistance among gram-negative bacteria in relation to antibiotic use in Prince Hashem Hospital (PHH), Jordan. One hundred consecutive gram-negative bacterial isolates from different sites were collected from patients admitted to the ICU at PHH. The susceptibilities of the strains to 12 antibiotics were performed and interpreted. The quantities and the numbers of the patients discharged on antibiotics and the quantities consumed were obtained from the hospital pharmacy records. The most common isolate was P. aeruginosa (n=21) The most common site of isolation was the respiratory tract (65%), The highest susceptibility was to piperacillin/ tazobactam(78%), and the lowest was to cefuroxime(34%). The aminoglycosides gentamicin and amikacin were active against 71% and 73% of the isolates respectively, Ciprofloxacin was active against 75% of the isolates. The most frequently used antibiotics were the third-generation cephalosporins ceftriaxone and ceftazidime, followed by imipenem and amikacin. Antibiotic resistance surveillance programs associated with registration of antibiotic consumption are necessary to promote optimal use of antibiotics. Rational prescribing of antibiotics should be encouraged through educational programs, surveillance and audit. Proper infection control measures should be practiced to prevent horizontal transfer of drug-resistant organisms. (author)

  6. Antibacterial activity of crude extract of Punica granatum pericarp on pathogenic Gram-negative bacilli.

    Directory of Open Access Journals (Sweden)

    Voravuthikunchai, S.

    2005-08-01

    Full Text Available The objective of this study was to investigate the effect of crude extracts of Punica granatum Linn. pericarp with 3 different solvents against pathogenic Gram-negative bacilli. Ethanolic extracts showed the antibacterial activity against all strains tested including enterohaemorrhagic Escherichia coli 4 strains (E. coli O157: H7, E. coli O26: H11, E. coli O111: NM, E. coli O22, Pseudomonas aeruginosa, Shigella boydii and Salmonella london. Inhibition zones ranged from 10.02 to 19.15 mm. Minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC ranged from 0.09 to 3.13 mg/ml and 3.13 to 25 mg/ml, respectively. Aqueous extract had low antibacterial activity while crude chloroform extracts had no effect on the growth of these strains. Ethyl acetate and n-butanol fractions of P. granatum pericarp demonstrated high activity with the best MIC and MBC values of 0.02 to 0.78 mg/ml and 0.19 to 6.25 mg/ml, respectively. As ethanolic extract of P. granatum was very effective against these pathogenic bacteria, further investigation on this plant species may provide alternative, but bioactive, medicines for the treatment of Gram-negative bacterial infection.

  7. Engineered endolysin-based "Artilysins" to combat multidrug-resistant gram-negative pathogens.

    Science.gov (United States)

    Briers, Yves; Walmagh, Maarten; Van Puyenbroeck, Victor; Cornelissen, Anneleen; Cenens, William; Aertsen, Abram; Oliveira, Hugo; Azeredo, Joana; Verween, Gunther; Pirnay, Jean-Paul; Miller, Stefan; Volckaert, Guido; Lavigne, Rob

    2014-07-01

    The global threat to public health posed by emerging multidrug-resistant bacteria in the past few years necessitates the development of novel approaches to combat bacterial infections. Endolysins encoded by bacterial viruses (or phages) represent one promising avenue of investigation. These enzyme-based antibacterials efficiently kill Gram-positive bacteria upon contact by specific cell wall hydrolysis. However, a major hurdle in their exploitation as antibacterials against Gram-negative pathogens is the impermeable lipopolysaccharide layer surrounding their cell wall. Therefore, we developed and optimized an approach to engineer these enzymes as outer membrane-penetrating endolysins (Artilysins), rendering them highly bactericidal against Gram-negative pathogens, including Pseudomonas aeruginosa and Acinetobacter baumannii. Artilysins combining a polycationic nonapeptide and a modular endolysin are able to kill these (multidrug-resistant) strains in vitro with a 4 to 5 log reduction within 30 min. We show that the activity of Artilysins can be further enhanced by the presence of a linker of increasing length between the peptide and endolysin or by a combination of both polycationic and hydrophobic/amphipathic peptides. Time-lapse microscopy confirmed the mode of action of polycationic Artilysins, showing that they pass the outer membrane to degrade the peptidoglycan with subsequent cell lysis. Artilysins are effective in vitro (human keratinocytes) and in vivo (Caenorhabditis elegans). Importance: Bacterial resistance to most commonly used antibiotics is a major challenge of the 21st century. Infections that cannot be treated by first-line antibiotics lead to increasing morbidity and mortality, while millions of dollars are spent each year by health care systems in trying to control antibiotic-resistant bacteria and to prevent cross-transmission of resistance. Endolysins--enzymes derived from bacterial viruses--represent a completely novel, promising class of

  8. New transposon tools tailored for metabolic engineering of Gram-negative microbial cell factories

    Directory of Open Access Journals (Sweden)

    Esteban eMartínez-García

    2014-10-01

    Full Text Available Re-programming microorganisms to modify their existing functions and/or to bestow bacteria with entirely new-to-Nature tasks have largely relied so far on specialized molecular biology tools. Such endeavors are not only relevant in the burgeoning metabolic engineering arena, but also instrumental to explore the functioning of complex regulatory networks from a fundamental point of view. À la carte modification of bacterial genomes thus calls for novel tools to make genetic manipulations easier. We propose the use of a series of new broad-host-range mini-Tn5 vectors, termed pBAMDs, for the delivery of gene(s into the chromosome of Gram-negative bacteria and for generating saturated mutagenesis libraries in gene function studies. These delivery vectors endow the user with the possibility of easy cloning and subsequent insertion of functional cargoes with three different antibiotic resistance markers (kanamycin, streptomycin, and gentamicin. After validating the pBAMD vectors in the environmental bacterium Pseudomonas putida KT2440, their use was also illustrated by inserting the entire poly(3-hydroxybutyrate (PHB synthesis pathway from Cupriavidus necator in the chromosome of a phosphotransacetylase mutant of Escherichia coli. PHB is a completely biodegradable polyester with a number of industrial applications that make it attractive as a potential replacement of oil-based plastics. The non-selective nature of chromosomal insertions of the biosynthetic genes was evidenced by a large landscape of PHB synthesis levels in independent clones. One clone was selected and further characterized as a microbial cell factory for PHB accumulation, and it achieved polymer accumulation levels comparable to those of a plasmid-bearing recombinant. Taken together, our results demonstrate that the new mini-Tn5 vectors can be used to confer interesting phenotypes in Gram-negative bacteria that would be very difficult to engineer through direct manipulation of the

  9. New Transposon Tools Tailored for Metabolic Engineering of Gram-Negative Microbial Cell Factories

    International Nuclear Information System (INIS)

    Martínez-García, Esteban; Aparicio, Tomás; Lorenzo, Víctor de; Nikel, Pablo I.

    2014-01-01

    Re-programming microorganisms to modify their existing functions and/or to bestow bacteria with entirely new-to-Nature tasks have largely relied so far on specialized molecular biology tools. Such endeavors are not only relevant in the burgeoning metabolic engineering arena but also instrumental to explore the functioning of complex regulatory networks from a fundamental point of view. À la carte modification of bacterial genomes thus calls for novel tools to make genetic manipulations easier. We propose the use of a series of new broad-host-range mini-Tn5-vectors, termed pBAMDs, for the delivery of gene(s) into the chromosome of Gram-negative bacteria and for generating saturated mutagenesis libraries in gene function studies. These delivery vectors endow the user with the possibility of easy cloning and subsequent insertion of functional cargoes with three different antibiotic-resistance markers (kanamycin, streptomycin, and gentamicin). After validating the pBAMD vectors in the environmental bacterium Pseudomonas putida KT2440, their use was also illustrated by inserting the entire poly(3-hydroxybutyrate) (PHB) synthesis pathway from Cupriavidus necator in the chromosome of a phosphotransacetylase mutant of Escherichia coli. PHB is a completely biodegradable polyester with a number of industrial applications that make it attractive as a potential replacement of oil-based plastics. The non-selective nature of chromosomal insertions of the biosynthetic genes was evidenced by a large landscape of PHB synthesis levels in independent clones. One clone was selected and further characterized as a microbial cell factory for PHB accumulation, and it achieved polymer accumulation levels comparable to those of a plasmid-bearing recombinant. Taken together, our results demonstrate that the new mini-Tn5-vectors can be used to confer interesting phenotypes in Gram-negative bacteria that would be very difficult to engineer through direct manipulation of the structural genes.

  10. Antimicrobial Peptide Potency is Facilitated by Greater Conformational Flexibility when Binding to Gram-negative Bacterial Inner Membranes

    Science.gov (United States)

    Amos, Sarah-Beth T. A.; Vermeer, Louic S.; Ferguson, Philip M.; Kozlowska, Justyna; Davy, Matthew; Bui, Tam T.; Drake, Alex F.; Lorenz, Christian D.; Mason, A. James

    2016-11-01

    The interaction of antimicrobial peptides (AMPs) with the inner membrane of Gram-negative bacteria is a key determinant of their abilities to exert diverse bactericidal effects. Here we present a molecular level understanding of the initial target membrane interaction for two cationic α-helical AMPs that share structural similarities but have a ten-fold difference in antibacterial potency towards Gram-negative bacteria. The binding and insertion from solution of pleurocidin or magainin 2 to membranes representing the inner membrane of Gram-negative bacteria, comprising a mixture of 128 anionic and 384 zwitterionic lipids, is monitored over 100 ns in all atom molecular dynamics simulations. The effects of the membrane interaction on both the peptide and lipid constituents are considered and compared with new and published experimental data obtained in the steady state. While both magainin 2 and pleurocidin are capable of disrupting bacterial membranes, the greater potency of pleurocidin is linked to its ability to penetrate within the bacterial cell. We show that pleurocidin displays much greater conformational flexibility when compared with magainin 2, resists self-association at the membrane surface and penetrates further into the hydrophobic core of the lipid bilayer. Conformational flexibility is therefore revealed as a key feature required of apparently α-helical cationic AMPs for enhanced antibacterial potency.

  11. LPS-binding protein-deficient mice have an impaired defense against Gram-negative but not Gram-positive pneumonia

    NARCIS (Netherlands)

    Branger, Judith; Florquin, Sandrine; Knapp, Sylvia; Leemans, Jaklien C.; Pater, Jennie M.; Speelman, Peter; Golenbock, Douglas T.; van der Poll, Tom

    2004-01-01

    LPS-binding protein (LBP) can facilitate the transfer of cell wall components of both Gram-negative bacteria (LPS) and Gram-positive bacteria (lipoteichoic acid) to inflammatory cells. Although LBP is predominantly produced in the liver, recent studies have indicated that this protein is also

  12. Nonfermenting Gram-negative Bacilli other than Pseudomonas aeruginosa and Acinetobacter Spp. Causing Respiratory Tract Infections in a Tertiary Care Center

    Directory of Open Access Journals (Sweden)

    Kisumu Chawla

    2013-01-01

    Full Text Available Background: Nonfermenting gram-negative bacilli have emerged as important healthcare-associated pathogens. It is important to correctly identify all clinically significant nonfermenting gram-negative bacilli considering the intrinsic multidrug resistance exhibited by these bacteria. Materials and Methods: A retrospective study was undertaken to identify the various nonfermenting gram-negative bacilli other than Pseudomonas aeruginosa and Acinetobacter spp. isolated from respiratory samples (n = 9363, to understand their clinical relevance and to analyze their antibiotic susceptibility pattern. Results: Nonfermenting gram-negative bacilli were isolated from 830 (16.4% samples showing significant growth. Thirty-three (4% isolates constituted nonfermenting gram-negative bacilli other than P. aeruginosa and Acinetobacter spp. Stenotrophomonas maltophilia (15, 45.5% was the most common isolate followed by Burkholderia cepacia (4, 12.1%, Sphingomonas paucimobilis (3, 9.1%, and Achromobacter xylosoxidans (3, 9.1%. On the basis of clinicomicrobiological correlation, pathogenicity was observed in 69.7% (n = 23 isolates. Timely and correct treatment resulted in clinical improvement in 87.9% cases. Conclusion: Any nonfermenting gram-negative bacilli isolated from respiratory tract infection should not be ignored as mere contaminant, but correlated clinically for its pathogenic potential and identified using standard methods so as to institute appropriate and timely antibiotic coverage.

  13. Development of Quorum-Based Anti-Virulence Therapeutics Targeting Gram-Negative Bacterial Pathogens

    Directory of Open Access Journals (Sweden)

    Wen Shan Yew

    2013-08-01

    Full Text Available Quorum sensing is a cell density-dependent signaling phenomenon used by bacteria for coordination of population-wide phenotypes, such as expression of virulence genes, antibiotic resistance and biofilm formation. Lately, disruption of bacterial communication has emerged as an anti-virulence strategy with enormous therapeutic potential given the increasing incidences of drug resistance in pathogenic bacteria. The quorum quenching therapeutic approach promises a lower risk of resistance development, since interference with virulence generally does not affect the growth and fitness of the bacteria and, hence, does not exert an associated selection pressure for drug-resistant strains. With better understanding of bacterial communication networks and mechanisms, many quorum quenching methods have been developed against various clinically significant bacterial pathogens. In particular, Gram-negative bacteria are an important group of pathogens, because, collectively, they are responsible for the majority of hospital-acquired infections. Here, we discuss the current understanding of existing quorum sensing mechanisms and present important inhibitory strategies that have been developed against this group of pathogenic bacteria.

  14. Phenotypic and Genotypic Detection of Metallo-beta-lactamases among Imipenem-Resistant Gram Negative Isolates

    Directory of Open Access Journals (Sweden)

    Mohammad Mohammadzadeh

    2016-08-01

    Full Text Available Background:   Imipenem-resistant gram negative bacteria, resulting from metallo-beta-lactamase (MBLs-producing strains have been reported to be among the important causes of nosocomial infections and of serious therapeutic problem worldwide. Because of their broad range, potent carbapenemase activity and resistance to inhibitors, these enzymes can confer resistance to almost all beta-lactams. The prevalence of metallo-beta-lactamase among imipenem-resistant Acinetobacter spp., Pseudomonas spp. and Enerobacteriaceae isolates is determined.Methods:   In this descriptive study 864 clinical isolates of Acinetobacter spp., Pseudomonas spp. and Enterobacteriaceae, were initially tested for imipenem susceptibility. The metallo-beta-lactamase production was detected using combined disk diffusion, double disk synergy test, and Hodge test. Then all imipenem resistant isolates were tested by PCR for imp, vim and ndm genes. Results:   Among 864 isolates, 62 (7.17 % were imipenem-resistant. Positive phonetypic test for metallo-beta-lactamase was 40 (64.5%, of which 24 (17.1% and 16 (9.2% isolates were Acinetobacter spp. and Pseudomonas spp., respectively. By PCR method 30 (48.4% of imipenem resistant Acinetobacter, and Pseudomonas isolates were positive for MBL-producing genes. None of the Enterobacteriaceae isolates were positive for metallo-beta-lactamase activity. Conclusion:   The results of this study are indicative of the growing number of nosocomial infections associated with multidrug-resistant gram negative bacteria in this region leading to difficulties in antibiotic therapy. Thereby, using of phenotypic methods can be helpful for management of this problem.

  15. Intrathecal or intraventricular therapy for post-neurosurgical Gram-negative meningitis: matched cohort study.

    Science.gov (United States)

    Shofty, B; Neuberger, A; Naffaa, M E; Binawi, T; Babitch, T; Rappaport, Z H; Zaaroor, M; Sviri, G; Paul, M

    2016-01-01

    Gram-negative post-operative meningitis due to carbapenem-resistant bacteria (CR-GNPOM) is a dire complication of neurosurgical procedures. We performed a nested propensity-matched historical cohort study aimed at examining the possible benefit of intrathecal or intraventricular (IT/IV) antibiotic treatment for CR-GNPOM. We included consecutive adults with GNPOM in two centres between 2005 and 2014. Patients receiving combined systemic and IT/IV treatment were matched to patients receiving systemic treatment only. Matching was done based on the propensity of the patients to receive IT/IV treatment. We compared patient groups with 30-day mortality defined as the primary outcome. The cohort included 95 patients with GNPOM. Of them, 37 received IT/IV therapy in addition to systemic treatment (22 with colistin and 15 with amikacin), mostly as initial therapy, through indwelling cerebrospinal fluid drains. Variables associated with IT/IV therapy in the propensity score included no previous neurosurgery, time from admission to meningitis, presence of a urinary catheter and GNPOM caused by carbapenem-resistant Gram-negative bacteria. Following propensity matching, 23 patients given IT/IV therapy and 27 controls were analysed. Mortality was significantly lower with IT/IV therapy: 2/23 (8.7%) versus 9/27 (33.3%), propensity-adjusted OR 0.19, 95% CI 0.04-0.99. Death or neurological deterioration at 30 days, 14-day and in-hospital mortality were lower with IT/IV therapy (OR <0.4 for all) without statistically significant differences. Among patients discharged alive, those receiving IT/IV therapy did not experience more neurological deterioration. Serious adverse events with IT/IV therapy were not documented. Our results support the early use of IT antibiotic treatment for CR-GNPOM when a delivery method is available. Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  16. Isolation and Characterization of Gram Negative Obligate and ...

    African Journals Online (AJOL)

    Gamal Ebrahium Haridy Osman

    2012-05-22

    May 22, 2012 ... from a variety of ecosystems including soil (Guffanti et al., 1986). There are only a few reports on alkalophilic bacteria isolated from Saudi Arabia (Salama et al., 1993). The objectives of this study were to isolate, characterize and identify alkalophilic bacteria from the western region of Kingdom of Saudi ...

  17. Raman Spectroscopy of Xylitol Uptake and Metabolism in Gram-Positive and Gram-Negative Bacteria▿

    Science.gov (United States)

    Palchaudhuri, Sunil; Rehse, Steven J.; Hamasha, Khozima; Syed, Talha; Kurtovic, Eldar; Kurtovic, Emir; Stenger, James

    2011-01-01

    Visible-wavelength Raman spectroscopy was used to investigate the uptake and metabolism of the five-carbon sugar alcohol xylitol by Gram-positive viridans group streptococcus and the two extensively used strains of Gram-negative Escherichia coli, E. coli C and E. coli K-12. E. coli C, but not E. coli K-12, contains a complete xylitol operon, and the viridans group streptococcus contains an incomplete xylitol operon used to metabolize the xylitol. Raman spectra from xylitol-exposed viridans group streptococcus exhibited significant changes that persisted even in progeny grown from the xylitol-exposed mother cells in a xylitol-free medium for 24 h. This behavior was not observed in the E. coli K-12. In both viridans group streptococcus and the E. coli C derivative HF4714, the metabolic intermediates are stably formed to create an anomaly in bacterial normal survival. The uptake of xylitol by Gram-positive and Gram-negative pathogens occurs even in the presence of other high-calorie sugars, and its stable integration within the bacterial cell wall may discontinue bacterial multiplication. This could be a contributing factor for the known efficacy of xylitol when taken as a prophylactic measure to prevent or reduce occurrences of persistent infection. Specifically, these bacteria are causative agents for several important diseases of children such as pneumonia, otitis media, meningitis, and dental caries. If properly explored, such an inexpensive and harmless sugar-alcohol, alone or used in conjunction with fluoride, would pave the way to an alternative preventive therapy for these childhood diseases when the causative pathogens have become resistant to modern medicines such as antibiotics and vaccine immunotherapy. PMID:21037297

  18. Antibiotic Resistance Patterns of Common Gram-negative Uropathogens in St. Paul's Hospital Millennium Medical College.

    Science.gov (United States)

    Mamuye, Yeshwondm

    2016-03-01

    The resistance of bacteria causing urinary tract infection (UTI) to commonly prescribed antibiotics is increasing both in developing and developed countries. Resistance has emerged even to more potent antimicrobial agents. This study was undertaken to determine the current antibiotic resistance pattern among common bacterial uropathogens in St.paul's Hospital Millennium Medical College. Using cross sectional study design, a total of 217 female and 207 male participants were consecutively recruited. Mid-urine samples were collected from all patients using wide mouthed urine cup. Inoculation was performed onto blood agar and MacConkey agar symoultaniously, and isolated organisms were identified by conventional methods. Antibiotic susceptibility was done by Kirby Bauer disk diffusion method. Thirteen different antibiotics representing different families of antibiotics were tested on all isolated organisms. Of the total 424 samples, 95(22.4%) showed significant growth. Gram negative organisms totaled 85(20.05%), and 10(2.4%) isolates were gram positive. The most frequently isolated gram negative bacterium was E. coli followed by Protues and Klebsiella spp. 53(12.5%), 8(8.4%), and 7(7.4%) respectively. Resistance to Tetracyclin, Ampicilin, Amoxycilin and Nalidixic Acid was more than 70% of all isolates of E.coli strains. There was relatively low resistance rate to Nitrofurantoin, Gentamycin and Trimethoprim-Sulfamethoxazole. However, there was emerging resistance to Ciprofloxacilin and Ceftriaxone especially for common bacteruria. In this study setting, resistant rates to Tetracyclin, Ampicilin, Amoxycilin and Nalidixic Acid were high. Since most isolates were sensitive for Nitrofurantoin, Gentamycin and Trimethoprim-Sulfamethoxazole, they are considered as appropriate antimicrobials for empirical treatment for urinary tract infections with the absence of culture and sensitivity setting. Increasing antibiotic resistance trends indicate that it is imperative to

  19. Effect of antigens from gram-positive and gram-negative bacteria, and of ŕ-gliadin on the intestinal epithelial cell lines HT-29, SW-480 and Caco-2

    Czech Academy of Sciences Publication Activity Database

    Funda, David P.; Farré, Maria Antionette; Horáková, Dana; Kolínská, Jiřina; Ceska, M.; Barot, R.; Tučková, Ludmila; Tlaskalová, Helena

    1997-01-01

    Roč. 75, č. 1 (1997), s. 52 ISSN 0818-9641. [International Congress of Mucosal Immunology /9./. 27.01.1997-31.01.1997, Sydney] R&D Projects: GA AV ČR IAA7020716; GA ČR GA310/96/1366; GA MZd IZ3761

  20. Does the empiric use of vancomycin in pediatrics increase the risk for Gram-negative bacteremia?

    NARCIS (Netherlands)

    Cuno, SPMU; Heesen, GJM; Arends, JP; Kimpen, JLL; van Houten, M.A.

    Background, Gram-negative bacteremia in children, a major cause of morbidity and mortality, may in part be induced by intensive treatment procedures and nonspecific use of antibiotics. Our primary objective was to study the causal relationship between the use of vancomycin and Gram-negative

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

    Directory of Open Access Journals (Sweden)

    Erika Coppo

    2011-06-01

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

  2. RECOVERY OF MURINE MYELOPOIESIS AFTER CYTOSTATIC REDUCTION BY ARA-C - EFFECT OF BACITRACIN-INDUCED CHANGES IN THE INTESTINAL MICROFLORA AND INFLUENCE OF TIMING

    NARCIS (Netherlands)

    DAENEN, S; GORIS, H; DEBOER, F; HALIE, MR; VANDERWAAIJ, D

    1991-01-01

    The influence of intestinal flora modulation by oral bacitracin on the recovery of myelopoiesis after Ara-C was studied in C3H/Law mice. Bacitracin resulted in a 3-5 log increase of Gram-negative bacteria and a 10-fold increase of the intestinal endotoxin concentration. Initiation of bacitracin

  3. Bacteria, bile salts, and intestinal monosaccharide malabsorption

    Science.gov (United States)

    Gracey, Michael; Burke, Valerie; Oshin, Ademola; Barker, Judith; Glasgow, Eric F.

    1971-01-01

    Intestinal monosaccharide transport was studied in a series of rats with a self-filling jejunal blind loop using 3mM arbutin (p-hydroxyphenyl-B-glucoside) or 1mM D-fructose as substrate in vitro and 10 mM arbutin or 5mM D-fructose in vivo. These results were compared with changes in the bacterial flora and state of conjugation of intraluminal bile salts in those animals. Observations were also made of the microscopic and ultrastructural appearances of the small-intestinal epithelium. In the small intestine of blind-loop rats intestinal monosaccharide transport is impaired, and in vitro is most marked in the blind loop, less so in the efferent jejunum, and not significantly altered in the afferent jejunum. A similar pattern of disturbed monosaccharide absorption was demonstrated by perfusions in vivo. The degree of the transport defect correlates closely with the luxuriance of the anaerobic flora, which averaged 108 per millilitre in the blind loop, 107 in the efferent jejunum, and 106 in the afferent jejunum. A similar pattern of abnormality of bile salt conjugation occurred. In the blind loop the ratio of free to conjugated bile salts was grossly abnormal; this disturbance was somewhat less marked in the efferent jejunum and considerably less in the intraluminal contents of the afferent jejunum. An irregularly distributed lesion, consisting of swelling and vacuolation of microvilli and intracellular organelles, was demonstrated in the small-intestinal epithelium of blind-loop animals. Impaired absorption of monosaccharides is a further consequence of bacterial contamination of the upper gut. It is suggested that this defect is caused by the presence of high levels of deconjugated bile salts produced by an abnormal anaerobic bacterial flora in the small intestine. ImagesFig. 3Fig. 4 PMID:4329096

  4. Intestinal bacteria and the regulation of immune cell homeostasis.

    Science.gov (United States)

    Hill, David A; Artis, David

    2010-01-01

    The human intestine is colonized by an estimated 100 trillion bacteria. Some of these bacteria are essential for normal physiology, whereas others have been implicated in the pathogenesis of multiple inflammatory diseases including IBD and asthma. This review examines the influence of signals from intestinal bacteria on the homeostasis of the mammalian immune system in the context of health and disease. We review the bacterial composition of the mammalian intestine, known bacterial-derived immunoregulatory molecules, and the mammalian innate immune receptors that recognize them. We discuss the influence of bacterial-derived signals on immune cell function and the mechanisms by which these signals modulate the development and progression of inflammatory disease. We conclude with an examination of successes and future challenges in using bacterial communities or their products in the prevention or treatment of human disease.

  5. IN VZTRO SUSCEPTIBILITY OF GRAM-NEGATIVE BACTERIAL ...

    African Journals Online (AJOL)

    respiratory infection and nonprophylactic systemic antibiotic use in patients undergoing heart surgery. Chest. 1996; 109: 1556-1561. 25. Wilson, M., Bansal, G., Stanley, A. and Newman, H.N.. Susceptibility of oral bacteria to phenoxyethanol and phenoxyethanol/chlorhexidine. J. Periodontol. 1990;. 61: 536-541.

  6. Antibiotic Resistance Patterns of Common Gram-negative ...

    African Journals Online (AJOL)

    Background: The resistance of bacteria causing urinary tract infection (UTI) to commonly prescribed antibiotics is increasing both in developing and developed countries. Resistance has emerged even to more potent antimicrobial agents. This study was undertaken to determine the current antibiotic resistance pattern ...

  7. Antagonistic effect of brevicin on Gram positive and Gram negative ...

    African Journals Online (AJOL)

    A new low molecular weight brevicin produced by Lactobacillus brevis NS01 has greater antimicrobial activity on Gram positive and negative food borne bacteria. This is stable at high temperature acidic to neutral pH, non proteolytic enzymes and organic solvents. The synergistic effect of brevicin with ...

  8. Infection-related hemolysis and susceptibility to Gram-negative bacterial co-infection

    Directory of Open Access Journals (Sweden)

    Katharine eOrf

    2015-06-01

    Full Text Available Increased susceptibility to co-infection with enteric Gram-negative bacteria, particularly non-typhoidal Salmonella, is reported in malaria and Oroya fever (Bartonella bacilliformis infection, and can lead to increased mortality. Accumulating epidemiological evidence indicates a causal association with risk of bacterial co-infection, rather than just co-incidence of common risk factors. Both malaria and Oroya fever are characterised by hemolysis, and observations in humans and animal models suggest that hemolysis causes the susceptibility to bacterial co-infection. Evidence from animal models implicates hemolysis in the impairment of a variety of host defence mechanisms, including macrophage dysfunction, neutrophil dysfunction and impairment of adaptive immune responses. One mechanism supported by evidence from animal models and human data, is the induction of heme oxygenase-1 in bone marrow, which impairs the ability of developing neutrophils to mount a competent oxidative burst. As a result, dysfunctional neutrophils become a new niche for replication of intracellular bacteria. Here we critically appraise and summarize the key evidence for mechanisms which may contribute to these very specific combinations of co-infections, and propose interventions to ameliorate this risk.

  9. Emergence of integron borne PER-1 mediated extended spectrum cephalosporin resistance among nosocomial isolates of Gram-negative bacilli

    Science.gov (United States)

    Maurya, Anand Prakash; Choudhury, Debarati; Talukdar, Anupam Das; Dhar (Chanda), Debadatta; Chakravarty, Atanu; Bhattacharjee, Amitabha

    2015-01-01

    Background & objectives: Pseudomonas extended resistant (PER) enzymes are rare type of extended-spectrum beta lactamases (ESBLs) that confer third generation cephalosporin resistance. These are often integron borne and laterally transmitted. The aim of the present study was to investigate the emergence of integron borne cephalosporin resistant PER-1 gene in diverse incompatibility (Inc) group plasmids among Gram-negative bacteria. Methods: A total of 613 consecutive, non-duplicate, Gram-negative bacteria of Enterobacteriaceae family and non-fermenting Gram-negative bacteria were isolated from different clinical specimens during a period of 18 months. For amplification and detection of blaPER, multiplex PCR was done. For understanding the genetic environment of blaPER-1, integrase gene PCR and cassette PCR (59 be) was performed. Gene transferability experiment was carried out and PCR based replicon typing was performed for incompatibility group typing of plasmids using 18 pairs of primers. An inhibitor based method was used for phenotypic detection of intrinsic resistance. Results: Multiplex PCR and sequencing confirmed that 45 isolates were harbouring blaPER-1. Both class 1 and class 2 integrons were observed among them. Integrase and cassette PCR (59 be) PCR results confirmed that the resistant determinant was located within class 1 integron. Transformation and conjugation experiments revealed that PER-1 was laterally transferable and disseminated through diverse Inc plasmid type. Efflux pump mediated carbapenem resistance was observed in all isolates. All isolates belonged to heterogenous groups. Interpretation & conclusions: This study demonstrates the dissemination of cephalosporins resistant, integron borne blaPER-1 in hospital setting in this part of the country and emphasizes on the rational use of third generation cephalosporins to slow down the expansion of this rare type of ESBL gene. PMID:26205025

  10. Emergence of integron borne PER-1 mediated extended spectrum cephalosporin resistance among nosocomial isolates of Gram-negative bacilli.

    Science.gov (United States)

    Maurya, Anand Prakash; Choudhury, Debarati; Talukdar, Anupam Das; Dhar Chanda, Debadatta; Chakravarty, Atanu; Bhattacharjee, Amitabha

    2015-06-01

    Pseudomonas extended resistant (PER) enzymes are rare type of extended-spectrum beta lactamases (ESBLs) that confer third generation cephalosporin resistance. These are often integron borne and laterally transmitted. The aim of the present study was to investigate the emergence of integron borne cephalosporin resistant PER-1 gene in diverse incompatibility (Inc) group plasmids among Gram-negative bacteria. A total of 613 consecutive, non-duplicate, Gram-negative bacteria of Enterobacteriaceae family and non-fermenting Gram-negative bacteria were isolated from different clinical specimens during a period of 18 months. For amplification and detection of blaPER, multiplex PCR was done. For understanding the genetic environment of blaPER-1, integrase gene PCR and cassette PCR (59 be) was performed. Gene transferability experiment was carried out and PCR based replicon typing was performed for incompatibility group typing of plasmids using 18 pairs of primers. An inhibitor based method was used for phenotypic detection of intrinsic resistance. Multiplex PCR and sequencing confirmed that 45 isolates were harbouring blaPER-1. Both class 1 and class 2 integrons were observed among them. Integrase and cassette PCR (59 be) PCR results confirmed that the resistant determinant was located within class 1 integron. Transformation and conjugation experiments revealed that PER-1 was laterally transferable and disseminated through diverse Inc plasmid type. Efflux pump mediated carbapenem resistance was observed in all isolates. All isolates belonged to heterogenous groups. This study demonstrates the dissemination of cephalosporins resistant, integron borne blaPER-1 in hospital setting in this part of the country and emphasizes on the rational use of third generation cephalosporins to slow down the expansion of this rare type of ESBL gene.

  11. Emergence of integron borne PER-1 mediated extended spectrum cephalosporin resistance among nosocomial isolates of Gram-negative bacilli

    Directory of Open Access Journals (Sweden)

    Anand Prakash Maurya

    2015-01-01

    Full Text Available Background & objectives: Pseudomonas extended resistant (PER enzymes are rare type of extended-spectrum beta lactamases (ESBLs that confer third generation cephalosporin resistance. These are often integron borne and laterally transmitted. The aim of the present study was to investigate the emergence of integron borne cephalosporin resistant PER-1 gene in diverse incompatibility (Inc group plasmids among Gram-negative bacteria. Methods: A total of 613 consecutive, non-duplicate, Gram-negative bacteria of Enterobacteriaceae family and non-fermenting Gram-negative bacteria were isolated from different clinical specimens during a period of 18 months. For amplification and detection of blaPER, multiplex PCR was done. For understanding the genetic environment of blaPER-1, integrase gene PCR and cassette PCR (59 be was performed. Gene transferability experiment was carried out and PCR based replicon typing was performed for incompatibility group typing of plasmids using 18 pairs of primers. An inhibitor based method was used for phenotypic detection of intrinsic resistance. Results: Multiplex PCR and sequencing confirmed that 45 isolates were harbouring blaPER-1. Both class 1 and class 2 integrons were observed among them. Integrase and cassette PCR (59 be PCR results confirmed that the resistant determinant was located within class 1 integron. Transformation and conjugation experiments revealed that PER-1 was laterally transferable and disseminated through diverse Inc plasmid type. Efflux pump mediated carbapenem resistance was observed in all isolates. All isolates belonged to heterogenous groups. Interpretation & conclusions: This study demonstrates the dissemination of cephalosporins resistant, integron borne blaPER-1 in hospital setting in this part of the country and emphasizes on the rational use of third generation cephalosporins to slow down the expansion of this rare type of ESBL gene.

  12. Fermentative Degradation of Polyethylene Glycol by a Strictly Anaerobic, Gram-Negative, Nonsporeforming Bacterium, Pelobacter venetianus sp. nov

    OpenAIRE

    1983-01-01

    The synthetic polyether polyethylene glycol (PEG) with a molecular weight of 20,000 was anaerobically degraded in enrichment cultures inoculated with mud of limnic and marine origins. Three strains (Gra PEG 1, Gra PEG 2, and Ko PEG 2) of rod-shaped, gram-negative, nonsporeforming, strictly anaerobic bacteria were isolated in mineral medium with PEG as the sole source of carbon and energy. All strains degraded dimers, oligomers, and polymers of PEG up to a molecular weight of 20,000 completely...

  13. Potential role of non-antibiotics (helper compounds) in the treatment of multidrug-resistant Gram-negative infections

    DEFF Research Database (Denmark)

    Martins, Marta; Dastidar, Sujata G; Fanning, Seamus

    2008-01-01

    Multidrug resistance in Gram-negative bacteria is now known to be primarily caused by overexpression of efflux pumps that extrude unrelated antibiotics from the periplasm or cytoplasm of the bacterium prior to their reaching their intended target. This review focuses on a variety of agents...... that have been shown to be efflux pump inhibitors (EPIs) and which, if used as 'helper compounds' in combination with antibiotics to which the organism is initially resistant, may produce the required cure. Although not all of the EPIs may serve a helper role owing to their toxicity, they may nevertheless...

  14. Incidence of carbapenem resistant nonfermenting gram negative bacilli from patients with respiratory infections in the intensive care units

    Directory of Open Access Journals (Sweden)

    Gladstone P

    2005-01-01

    Full Text Available Resistance to carbapenems is commonly seen in nonfermenting gram negative bacilli (NFGNB. We document herein the prevalence of carbapenem resistance in NFGNB isolated from patients with respiratory tract infections in the intensive care units (ICUs. A total of 460 NFGNB were isolated from 606 endotracheal aspirate specimens during January through December 2003, of which 56 (12.2% were found to be resistant to imipenem and meropenem. Of these, 24 (42.8% were Pseudomonas aeruginosa , 8 (14.2% were Acinetobacter spp. and 24 (42.8% were other NFGNB. Stringent protocols such as antibiotic policies and resistance surveillance programs are mandatory to curb these bacteria in ICU settings.

  15. Evaluation of an expanded microarray for detecting antibiotic resistance genes in a broad range of gram-negative bacterial pathogens.

    Science.gov (United States)

    Card, Roderick; Zhang, Jiancheng; Das, Priya; Cook, Charlotte; Woodford, Neil; Anjum, Muna F

    2013-01-01

    A microarray capable of detecting genes for resistance to 75 clinically relevant antibiotics encompassing 19 different antimicrobial classes was tested on 132 Gram-negative bacteria. Microarray-positive results correlated >91% with antimicrobial resistance phenotypes, assessed using British Society for Antimicrobial Chemotherapy clinical breakpoints; the overall test specificity was >83%. Microarray-positive results without a corresponding resistance phenotype matched 94% with PCR results, indicating accurate detection of genes present in the respective bacteria by microarray when expression was low or absent and, hence, undetectable by susceptibility testing. The low sensitivity and negative predictive values of the microarray results for identifying resistance to some antimicrobial resistance classes are likely due to the limited number of resistance genes present on the current microarray for those antimicrobial agents or to mutation-based resistance mechanisms. With regular updates, this microarray can be used for clinical diagnostics to help accurate therapeutic options to be taken following infection with multiple-antibiotic-resistant Gram-negative bacteria and prevent treatment failure.

  16. First detection of bla TEM, SHV and CTX-M among Gram negative ...

    African Journals Online (AJOL)

    First detection of bla TEM, SHV and CTX-M among Gram negative bacilli exhibiting extended spectrum β- lactamase phenotype isolated at University Hospital Center, Yalgado Ouedraogo, Ouagadougou, Burkina Faso.

  17. Gram-negative rod bacteremia after cardiovascular surgery: Clinical features and prognostic factors

    Directory of Open Access Journals (Sweden)

    Sayaka Tago

    2017-06-01

    Conclusion: Graft replacement was the most common surgical procedure in patients with GNRB after CVS. Empirical antibiotics covering Gram-negative rods including P. aeruginosa should be considered if bacteremia is suspected in unstable patients after CVS.

  18. Interleukin 10 overexpression alters survival in the setting of gram-negative pneumonia following lung contusion.

    Science.gov (United States)

    Dolgachev, Vladislav A; Yu, Bi; Sun, Lei; Shanley, Thomas P; Raghavendran, Krishnan; Hemmila, Mark R

    2014-04-01

    Lung contusion injury produces a vulnerable window within the inflammatory defenses of the lung that predisposes the patient to pneumonia. Interleukin 10 (IL-10) is a known anti-inflammatory mediator produced by macrophages and capable of downregulating acute lung inflammation. We investigated the impact of increased levels of IL-10 within the lung on survival and the host response to trauma in the setting of lung contusion (LC) and gram-negative pneumonia. A bitransgenic, tetracycline-inducible, lung-specific human IL-10 overexpression (IL-10 OE) mouse model and single transgenic (TG-) control mice were used. Mice underwent LC injury or sham injury (sham) at time -6 h. At time 0, animals were inoculated intratracheally with 500 colony-forming units of Klebsiella pneumoniae (pneu). Bronchoalveolar lavage fluid, lung tissue specimens, or purified macrophages were collected. Lung tissue and blood bacteria levels were quantified. Cytokine levels were assayed by enzyme-linked immunosorbent assay, and gene expression levels were evaluated by real-time polymerase chain reaction. Cell-type identification and quantification were done using real-time polymerase chain reaction and flow cytometry. Interleukin 10 OE mice demonstrated decreased 5-day survival compared with TG- mice following LC + pneu (0 vs. 30%, P pneu animals (P < 0.05). Lung-specific IL-10 overexpression induces alternative activation of alveolar macrophages. This shift in macrophage phenotype decreases intracellular bacterial killing, resulting in a more pronounced bacteremia and accelerated mortality in a model of LC and pneumonia.

  19. IL-10 Overexpression Alters Survival in the Setting of Gram Negative Pneumonia Following Lung Contusion

    Science.gov (United States)

    Dolgachev, Vladislav A.; Yu, Bi; Sun, Lei; Shanley, Thomas P.; Raghavendran, Krishnan; Hemmila, Mark R.

    2014-01-01

    Objective Lung contusion injury produces a vulnerable window within the inflammatory defenses of the lung that predisposes the patient to pneumonia. IL-10 is a known anti-inflammatory mediator produced by macrophages and capable of down-regulating acute lung inflammation. We investigated the impact of increased levels of IL-10 within the lung on survival and the host response to trauma in the setting of lung contusion and Gram-negative pneumonia. Design A bi-transgenic, tetracycline inducible, lung specific human IL-10 overexpression (IL-10 OE) mouse model and single transgenic (TG-) control mice were used. Mice underwent lung contusion injury (LC) or sham injury (Sham) at time -6 hrs. At time 0 animals were inoculated intratracheally with 500 CFU of Klebsiella pneumoniae (Pneu). Bronchoalveolar lavage fluid (BAL), lung tissue specimens, or purified macrophages were collected. Lung tissue and blood bacteria levels were quantified. Cytokine levels were assayed by ELISA and gene expression levels were evaluated by real time PCR. Cell type identification and quantification was done using real time PCR and flow cytometry. Main Results IL-10 OE mice demonstrated decreased 5 day survival compared to TG-mice following LC+Pneu (0 vs. 30%, pPneu animals (p<0.05). Conclusions Lung specific IL-10 over expression induces alternative activation of alveolar macrophages. This shift in macrophage phenotype decreases intracellular bacterial killing, resulting in a more pronounced bacteremia and accelerated mortality in a model of lung contusion and pneumonia. PMID:24430542

  20. Membrane permeabilization of colistin toward pan-drug resistant Gram-negative isolates.

    Science.gov (United States)

    Mohamed, Yasmine Fathy; Abou-Shleib, Hamida Moustafa; Khalil, Amal Mohamed; El-Guink, Nadia Mohamed; El-Nakeeb, Moustafa Ahmed

    2016-01-01

    Pan-drug resistant Gram-negative bacteria, being resistant to most available antibiotics, represent a huge threat to the medical community. Colistin is considered the last therapeutic option for patients in hospital settings. Thus, we were concerned in this study to demonstrate the membrane permeabilizing activity of colistin focusing on investigating its efficiency toward those pan-drug resistant isolates which represent a critical situation. We determined the killing dynamics of colistin against pan-drug resistant isolates. The permeability alteration was confirmed by different techniques as: leakage, electron microscopy and construction of an artificial membrane model; liposomes. Moreover, selectivity of colistin against microbial cells was also elucidated. Colistin was proved to be rapid bactericidal against pan-drug resistant isolates. It interacts with the outer bacterial membrane leading to deformation of its outline, pore formation, leakage of internal contents, cell lysis and finally death. Furthermore, variations in membrane composition of eukaryotic and microbial cells provide a key for colistin selectivity toward bacterial cells. Colistin selectively alters membrane permeability of pan-drug resistant isolates which leads to cell lysis. Colistin was proved to be an efficient last line treatment for pan-drug resistant infections which are hard to treat. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  1. CXC Chemokines Exhibit Bactericidal Activity against Multidrug-Resistant Gram-Negative Pathogens

    Directory of Open Access Journals (Sweden)

    Matthew A. Crawford

    2017-11-01

    Full Text Available The continued rise and spread of antimicrobial resistance among bacterial pathogens pose a serious challenge to global health. Countering antimicrobial-resistant pathogens requires a multifaceted effort that includes the discovery of novel therapeutic approaches. Here, we establish the capacity of the human CXC chemokines CXCL9 and CXCL10 to kill multidrug-resistant Gram-negative bacteria, including New Delhi metallo-beta-lactamase-1-producing Klebsiella pneumoniae and colistin-resistant members of the family Enterobacteriaceae that harbor the mobile colistin resistance protein MCR-1 and thus possess phosphoethanolamine-modified lipid A. Colistin-resistant K. pneumoniae isolates affected by genetic mutation of the PmrA/PmrB two-component system, a chromosomally encoded regulator of lipopolysaccharide modification, and containing 4-amino-4-deoxy-l-arabinose-modified lipid A were also found to be susceptible to chemokine-mediated antimicrobial activity. However, loss of PhoP/PhoQ autoregulatory control, caused by disruption of the gene encoding the negative regulator MgrB, limited the bactericidal effects of CXCL9 and CXCL10 in a variable, strain-specific manner. Cumulatively, these findings provide mechanistic insight into chemokine-mediated antimicrobial activity, highlight disparities amongst determinants of colistin resistance, and suggest that chemokine-mediated bactericidal effects merit additional investigation as a therapeutic avenue for treating infections caused by multidrug-resistant pathogens.

  2. Small-Molecule Inhibitors of Gram-Negative Lipoprotein Trafficking Discovered by Phenotypic Screening

    Science.gov (United States)

    Fleming, Paul R.; MacCormack, Kathleen; McLaughlin, Robert E.; Whiteaker, James D.; Narita, Shin-ichiro; Mori, Makiko; Tokuda, Hajime; Miller, Alita A.

    2015-01-01

    In Gram-negative bacteria, lipoproteins are transported to the outer membrane by the Lol system. In this process, lipoproteins are released from the inner membrane by the ABC transporter LolCDE and passed to LolA, a diffusible periplasmic molecular chaperone. Lipoproteins are then transferred to the outer membrane receptor protein, LolB, for insertion in the outer membrane. Here we describe the discovery and characterization of novel pyridineimidazole compounds that inhibit this process. Escherichia coli mutants resistant to the pyridineimidazoles show no cross-resistance to other classes of antibiotics and map to either the LolC or LolE protein of the LolCDE transporter complex. The pyridineimidazoles were shown to inhibit the LolA-dependent release of the lipoprotein Lpp from E. coli spheroplasts. These results combined with bacterial cytological profiling are consistent with LolCDE-mediated disruption of lipoprotein targeting to the outer membrane as the mode of action of these pyridineimidazoles. The pyridineimidazoles are the first reported inhibitors of the LolCDE complex, a target which has never been exploited for therapeutic intervention. These compounds open the door to further interrogation of the outer membrane lipoprotein transport pathway as a target for antimicrobial therapy. PMID:25583975

  3. Toll-like receptor 4 decoy, TOY, attenuates gram-negative bacterial sepsis.

    Directory of Open Access Journals (Sweden)

    Keehoon Jung

    Full Text Available Lipopolysaccharide (LPS, the Gram-negative bacterial outer membrane glycolipid, induces sepsis through its interaction with myeloid differentiation protein-2 (MD-2 and Toll-like receptor 4 (TLR4. To block interaction between LPS/MD-2 complex and TLR4, we designed and generated soluble fusion proteins capable of binding MD-2, dubbed TLR4 decoy receptor (TOY using 'the Hybrid leucine-rich repeats (LRR technique'. TOY contains the MD-2 binding ectodomain of TLR4, the LRR motif of hagfish variable lymphocyte receptor (VLR, and the Fc domain of IgG1 to make it soluble, productive, and functional. TOY exhibited strong binding to MD-2, but not to the extracellular matrix (ECM, resulting in a favorable pharmacokinetic profile in vivo. TOY significantly extended the lifespan, when administered in either preventive or therapeutic manners, in both the LPS- and cecal ligation/puncture-induced sepsis models in mice. TOY markedly attenuated LPS-triggered NF-kappaB activation, secretion of proinflammatory cytokines, and thrombus formation in multiple organs. Taken together, the targeting strategy for sequestration of LPS/MD-2 complex using the decoy receptor TOY is effective in treating LPS- and bacteria-induced sepsis; furthermore, the strategy used in TOY development can be applied to the generation of other novel decoy receptor proteins.

  4. Gram-negative trimeric porins have specific LPS binding sites that are essential for porin biogenesis

    Science.gov (United States)

    Arunmanee, Wanatchaporn; Pathania, Monisha; Solovyova, Alexandra S.; Le Brun, Anton P.; Ridley, Helen; Baslé, Arnaud; van den Berg, Bert; Lakey, Jeremy H.

    2016-01-01

    The outer membrane (OM) of gram-negative bacteria is an unusual asymmetric bilayer with an external monolayer of lipopolysaccharide (LPS) and an inner layer of phospholipids. The LPS layer is rigid and stabilized by divalent cation cross-links between phosphate groups on the core oligosaccharide regions. This means that the OM is robust and highly impermeable to toxins and antibiotics. During their biogenesis, OM proteins (OMPs), which function as transporters and receptors, must integrate into this ordered monolayer while preserving its impermeability. Here we reveal the specific interactions between the trimeric porins of Enterobacteriaceae and LPS. Isolated porins form complexes with variable numbers of LPS molecules, which are stabilized by calcium ions. In earlier studies, two high-affinity sites were predicted to contain groups of positively charged side chains. Mutation of these residues led to the loss of LPS binding and, in one site, also prevented trimerization of the porin, explaining the previously observed effect of LPS mutants on porin folding. The high-resolution X-ray crystal structure of a trimeric porin–LPS complex not only helps to explain the mutagenesis results but also reveals more complex, subtle porin–LPS interactions and a bridging calcium ion. PMID:27493217

  5. Small-molecule inhibitors of gram-negative lipoprotein trafficking discovered by phenotypic screening.

    Science.gov (United States)

    McLeod, Sarah M; Fleming, Paul R; MacCormack, Kathleen; McLaughlin, Robert E; Whiteaker, James D; Narita, Shin-Ichiro; Mori, Makiko; Tokuda, Hajime; Miller, Alita A

    2015-03-01

    In Gram-negative bacteria, lipoproteins are transported to the outer membrane by the Lol system. In this process, lipoproteins are released from the inner membrane by the ABC transporter LolCDE and passed to LolA, a diffusible periplasmic molecular chaperone. Lipoproteins are then transferred to the outer membrane receptor protein, LolB, for insertion in the outer membrane. Here we describe the discovery and characterization of novel pyridineimidazole compounds that inhibit this process. Escherichia coli mutants resistant to the pyridineimidazoles show no cross-resistance to other classes of antibiotics and map to either the LolC or LolE protein of the LolCDE transporter complex. The pyridineimidazoles were shown to inhibit the LolA-dependent release of the lipoprotein Lpp from E. coli spheroplasts. These results combined with bacterial cytological profiling are consistent with LolCDE-mediated disruption of lipoprotein targeting to the outer membrane as the mode of action of these pyridineimidazoles. The pyridineimidazoles are the first reported inhibitors of the LolCDE complex, a target which has never been exploited for therapeutic intervention. These compounds open the door to further interrogation of the outer membrane lipoprotein transport pathway as a target for antimicrobial therapy. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  6. Epidemiology and genetics of VIM-type metallo-β-lactamases in Gram-negative bacilli.

    Science.gov (United States)

    Zhao, Wei-Hua; Hu, Zhi-Qing

    2011-03-01

    Metallo-β-lactamases (MBLs) are a rapidly evolving group of β-lactamases, which hydrolyze most β-lactams including the carbapenems. Of the known MBLs, VIMs are one of the most common families, with 27 variants detected in at least 23 species of Gram-negative bacilli from more than 40 countries/regions. The amino acid similarities of VIM variants range from 72.9 to 99.6% with 1-72 different residues. Most of the bla (VIM)s are harbored by a class 1 integron, a genetic platform able to acquire and express gene cassettes. The integrons are usually embedded in transposons and, in turn, accommodated on plasmids, making them highly mobile. Integrons display considerable diversity, with at least 110 different structures associated with the gain and spread of the bla (VIM)s. In most instances, the bla (VIM)s co-exist with one or more other resistance genes. The processes for the identification of bacteria harboring bla (VIM)s are also discussed in this article.

  7. The horseshoe crab: a model for gram-negative sepsis in marine organisms and humans.

    Science.gov (United States)

    Levin, J

    1988-01-01

    The roles of the amebocyte in providing hemostasis and controlling infection, and its reaction to endotoxin, suggest that the response of platelets and the blood coagulation system in various mammals to gram-negative infection or endotoxin is an evolutionary remnant of this ancient mechanism. In humans, this mechanism occasionally subverts its presumed protective function by overresponding in a manner that results in pathophysiologic thrombosis or hemorrhage. (In this regard, it is interesting that human platelets are much more resistant to the effects of bacterial endotoxins than are other species.) Similarly, the rudimentary ability of mammalian platelets to phagocytose particles and kill bacteria may be another remnant of functions that are more important in amebocytes (or the thrombocytes of other invertebrates). Thus, these two cells, one from an ancient invertebrate and the other from mammals, have remarkably similar characteristics, although the relative importance of their various functions has changed as evolution has taken place. Nevertheless, after at least 400,000,000 years of evolution, coagulation and anti-bacterial mechanisms remain at least partially linked.

  8. Gram-Negative Bacterial Lipopolysaccharide Stimulates Activin A Secretion from Human Amniotic Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Yumiko Abe

    2013-01-01

    Full Text Available Activin A is involved in inflammation. The present study was performed to clarify if lipopolysaccharide, a component of Gram-negative bacteria, stimulates activin A secretion from human amniotic epithelial cells and to determine if activin A plays a role in amnionitis. Fetal membranes were obtained during elective cesarean sections performed in full-term pregnancies of patients without systemic disease, signs of premature delivery, or fetal complications. Amniotic epithelial cells were isolated by trypsinization. The activin A concentrations in the culture media were measured by enzyme-linked immunosorbent assay, and cell proliferation was assessed by 5-bromo-2′-deoxyuridine incorporation. Amniotic epithelial cells secreted activin A in a cell density-dependent manner, and lipopolysaccharide (10 μg/mL enhanced the secretion at each cell density. Lipopolysaccharide (10–50 μg/mL also stimulated activin A secretion in a dose-dependent manner. Contrary to the effect of activin A secretion, lipopolysaccharide inhibited cell proliferation in amniotic epithelial cells. The present study suggests that lipopolysaccharide stimulation of activin A secretion may be a mechanism in the pathogenesis of amnionitis.

  9. The resveratrol tetramer (--hopeaphenol inhibits type III secretion in the gram-negative pathogens Yersinia pseudotuberculosis and Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Caroline E Zetterström

    Full Text Available Society faces huge challenges, as a large number of bacteria have developed resistance towards many or all of the antibiotics currently available. Novel strategies that can help solve this problem are urgently needed. One such strategy is to target bacterial virulence, the ability to cause disease e.g., by inhibition of type III secretion systems (T3SSs utilized by many clinically relevant gram-negative pathogens. Many of the antibiotics used today originate from natural sources. In contrast, most virulence-blocking compounds towards the T3SS identified so far are small organic molecules. A recent high-throughput screening of a prefractionated natural product library identified the resveratrol tetramer (--hopeaphenol as an inhibitor of the T3SS in Yersinia pseudotuberculosis. In this study we have investigated the virulence blocking properties of (--hopeaphenol in three different gram-negative bacteria. (--Hopeaphenol was found to have micromolar activity towards the T3SSs in Yersinia pseudotuberculosis and Pseudomonas aeruginosa in cell-based infection models. In addition (--hopeaphenol reduced cell entry and subsequent intracellular growth of Chlamydia trachomatis.

  10. Comparison of E-test with other conventional susceptibility testing methods for ciprofloxacin and gentamicin against gram negative enteric bacilli.

    Science.gov (United States)

    Ogbolu, D O; Terry-Alli, O A; Daini, O A; Olabiyi, F A; Igharo, E A

    2012-06-01

    Increasing antibiotic resistance in Gram negative bacteria has led to the need for a faster and reliable method for determining antimicrobial susceptibility testing. In a resource poor setting like ours, it's also important to look for methods that will be clinically and economically beneficial to the patient. This study was aimed at evaluating the Epsilometer test (E-test) and conventional methods for determining antimicrobial susceptibility of isolates of Gram-negative enteric bacteria to ciprofloxacin and gentamicin. Disc diffusion, E-test, broth dilution and agar dilution methods were performed on 54 bacterial isolates. Using the E-test, 88.9% of bacterial isolates were resistant to ciprofloxacin, 92.6% were resistant using broth microdilution, 96.3% were resistant using agar dilution and 72.2% were resistant using disc diffusion. Minimum inhibitory concentration (MIC50) of isolates for gentamicin showed significant difference for all the techniques (p 0.05). Both E-test and broth dilution methods showed high levels of agreement (p > 0.05), there were low levels of agreement between E-test and agar dilution method (p < 0.05), especially at MIC50. The E-test can therefore be considered a reliable method to determine antimicrobial susceptibility testing and it gives results which are at least as accurate as those obtained by the broth dilution method.

  11. Trichokonins from Trichoderma pseudokoningii SMF2 induce resistance against Gram-negative Pectobacterium carotovorum subsp. carotovorum in Chinese cabbage.

    Science.gov (United States)

    Li, Hai-Yun; Luo, Yan; Zhang, Xiu-Sheng; Shi, Wei-Ling; Gong, Zhi-Ting; Shi, Mei; Chen, Lei-Lei; Chen, Xiu-Lan; Zhang, Yu-Zhong; Song, Xiao-Yan

    2014-05-01

    Peptaibols, mainly produced by Trichoderma, play a pivotal role in controlling plant disease caused by fungi, virus, and Gram-positive bacteria. In the current study, we evaluated the control effect of Trichokonins, antimicrobial peptaibols from Trichoderma pseudokoningii SMF2, on soft rot disease of Chinese cabbage caused by a Gram-negative bacterium Pectobacterium carotovorum subsp. carotovorum and analyzed the mechanism involved. Trichokonins treatment (0.3 mg L(-1) ) enhanced the resistance of Chinese cabbage against Pcc infection. However, Trichokonins could hardly inhibit the growth of Pcc in vitro, even at high concentration (500 mg L(-1) ). Therefore, the direct effect of Trichokonins on Pcc may not the main reason why Trichokonins could control soft rot of Chinese cabbage. Trichokonin treatment led to an obvious increase in the production of reactive oxygen species hydrogen peroxide and superoxide radical, a significant enhance of the activities of pathogenesis-related enzymes catalase, polyphenoloxidase and peroxidase, and upregulation of the expression of salicylic acid - responsive pathogenesis-related protein gene acidic PR-1a in Chinese cabbage. These results indicate that Trichokonins induce resistance in Chinese cabbage against Pcc infection through the activation of salicylic acid signaling pathway, which imply the potential of Trichoderma and peptaibols in controlling plant disease caused by Gram-negative bacteria. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  12. Modulation of the Interaction of Enteric Bacteria with Intestinal Mucosa by Stress-Related Catecholamines.

    Science.gov (United States)

    Stevens, Mark P

    2016-01-01

    Stress associated with parturition, transport or mixing has long been correlated with enhanced faecal excretion of diarrhoeal zoonotic pathogens in animals such as Salmonella enterica and Escherichia coli. It may also predispose humans to infection and/or be associated with more severe outcomes. One possible explanation for this phenomenon is the ability of enteric bacterial pathogens to sense and respond to host stress-related catecholamines. This article reviews evidence of the ability of catecholamine hormones to modulate interactions between Gram-negative diarrhoeal pathogens and intestinal mucosa, as well as the molecular mechanisms that may be at work.

  13. Analysis of surface protein expression reveals the growth pattern of the gram-negative outer membrane.

    Directory of Open Access Journals (Sweden)

    Tristan S Ursell

    Full Text Available The outer membrane (OM of Gram-negative bacteria is a complex bilayer composed of proteins, phospholipids, lipoproteins, and lipopolysaccharides. Despite recent advances revealing the molecular pathways underlying protein and lipopolysaccharide incorporation into the OM, the spatial distribution and dynamic regulation of these processes remain poorly understood. Here, we used sequence-specific fluorescent labeling to map the incorporation patterns of an OM-porin protein, LamB, by labeling proteins only after epitope exposure on the cell surface. Newly synthesized LamB appeared in discrete puncta, rather than evenly distributed over the cell surface. Further growth of bacteria after labeling resulted in divergence of labeled LamB puncta, consistent with a spatial pattern of OM growth in which new, unlabeled material was also inserted in patches. At the poles, puncta remained relatively stationary through several rounds of division, a salient characteristic of the OM protein population as a whole. We propose a biophysical model of growth in which patches of new OM material are added in discrete bursts that evolve in time according to Stokes flow and are randomly distributed over the cell surface. Simulations based on this model demonstrate that our experimental observations are consistent with a bursty insertion pattern without spatial bias across the cylindrical cell surface, with approximately one burst of ≈ 10(-2 µm(2 of OM material per two minutes per µm(2. Growth by insertion of discrete patches suggests that stochasticity plays a major role in patterning and material organization in the OM.

  14. Isolation and identification of intestinal bacteria from Japanese tree frog (Hlya japonica) with the special reference to anaerobic bacteria.

    Science.gov (United States)

    Benno, Y; Izumi-Kurotani, A; Yamashita, M

    1992-08-01

    The bacteria in the large intestines of eight Japanese tree frogs (Hlya japonica) were enumerated by using an anaerobic culture system. The microorganisms at approximately 3.1 x 10(9) bacteria per g (wet weight) of intestinal contents were present in the intestine of all the frogs tested. No difference of the total bacteria in the frog intestine was observed between two different incubation-temperatures (room temperature and 37 degrees C). Eleven genera and 16 species were isolated from the frog intestine. In most frogs, Bacteroides (B.) caccae and B. vulgatus were detected as the predominant organisms. Escherichia coli was also present in greater numbers in the intestine. Other bacteria isolated at high dilutions were strict anaerobes, including Fusobacterium and Clostridium. Enterococcus faecalis was frequently isolated from the frog intestine. However, four genera of Bifidobacterium, Eubacterium, Peptostreptococcus, and Lactobacillus were not isolated from the frog intestine.

  15. Gram-Negative Bacterial Infections: Research Priorities, Accomplishments, and Future Directions of the Antibacterial Resistance Leadership Group.

    Science.gov (United States)

    Doi, Yohei; Bonomo, Robert A; Hooper, David C; Kaye, Keith S; Johnson, James R; Clancy, Cornelius J; Thaden, Joshua T; Stryjewski, Martin E; van Duin, David

    2017-03-15

    Antimicrobial resistance in pathogenic gram-negative bacteria is one of the most pressing challenges in the field of infectious diseases and is one of 4 key areas of unmet medical need identified by the Antibacterial Resistance Leadership Group (ARLG). The mission of the Gram-Negative Committee is to advance our knowledge of these challenging infections and implement studies to improve patient outcomes. Studies have fallen primarily into 2 broad categories: prospective cohort studies and interventional trials. Among the observational studies, CRACKLE (Consortium on Resistance Against Carbapenems in Klebsiella pneumoniae and Other Enterobacteriaceae) has contributed seminal multicenter data describing risk factors and clinical outcomes of carbapenem-resistant Enterobacteriaceae (CRE) in sentinel US hospitals. Building on this success, CRACKLE II will expand the network to hospitals across the United States and Colombia. Similar protocols have been proposed to include Acinetobacter baumannii and Pseudomonas aeruginosa (SNAP and POP studies). In addition, the CREST study (Carbapenem-Resistant Enterobacteriaceae in Solid Organ Transplant Patients) has provided pivotal data on extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and CRE carriage among solid organ transplant recipients to inform management of this vulnerable patient population. Two clinical trials to define novel ways of using an existing antibiotic, fosfomycin, to treat ESBL-producing Enterobacteriaceae (one that has completed enrollment and the other in late protocol development) will determine the clinical efficacy of fosfomycin as step-down oral therapy to treat complicated urinary tract infections. Additional clinical studies and trials using immunotherapeutic or newly approved agents are also in the planning stage, with the main goals of generating actionable data that will inform clinical decision making and facilitate development of new treatment options for highly resistant gram-negative

  16. Screening of the novel colicinogenic gram-negative rods against pathogenic Escherichia coli O157:H7

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    H Mushtaq

    2015-01-01

    Full Text Available Purpose: Escherichia coli (E. coli O157:H7 is gram-negative enteric pathogen producing different types of Shiga toxin. This bacterium is the most corporate cause of haemorrhagic colitis in human. Administration of antibiotics (particularly sulfa drugs against this pathogen is a debatable topic as this may increase the risk of uremic syndrome; especially in children and aged people. Around the world, microbiologists are in search of alternative therapeutic methods specially probiotics against this pathogen. In the present study, we have focused on the investigation of alternate bio-therapeutics (probiotics for the treatment of patients infected with E. coli O157:H7. This study is based on the identification of colicin-producing gram-negative bacteria (particularly enterobacteriaceae which can competently exclude E. coli O157:H7 from the gut of the infected individual. Materials and Methods: Hundred samples from human, animal faeces and septic tank water were analysed for nonpathogenic gram-negative rods (GNRs. Results: Out of these samples, 175 isolates of GNRs were checked for their activity against E. coli O157:H7. Only 47 isolates inhibited the growth of E. coli O157:H7, among which majority were identified as E. coli. These E. coli strains were found to be the efficient producers of colicin. Some of the closely related species i. e., Citrobacter sp, Pantoea sp. and Kluyvera sp. also showed considerable colicinogenic activity. Moreover, colicinogenic species were found to be nonhaemolytic, tolerant to acidic environment (pH 3 and sensitive to commonly used antibiotics. Conclusion: Nonhaemolytic, acid tolerant and sensitive to antibiotics suggests the possible use of these circulating endothelial cells (CEC as inexpensive and inoffensive therapeutic agent (probiotics in E. coli O157:H7 infections.

  17. Probing interaction of Gram-positive and Gram-negative bacterial cells with ZnO nanorods

    International Nuclear Information System (INIS)

    Jain, Aanchal; Bhargava, Richa; Poddar, Pankaj

    2013-01-01

    In the present work, the physiological effects of the ZnO nanorods on the Gram positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Aerobacter aerogenes) bacterial cells have been studied. The analysis of bacterial growth curves for various concentrations of ZnO nanorods indicates that Gram positive and Gram negative bacterial cells show inhibition at concentrations of ∼ 64 and ∼ 256 μg/mL respectively. The marked difference in susceptibility towards nanorods was also validated by spread plate and disk diffusion methods. In addition, the scanning electron micrographs show a clear damage to the cells via changed morphology of the cells from rod to coccoid etc. The confocal optical microscopy images of these cells also demonstrate the reduction in live cell count in the presence of ZnO nanorods. These, results clearly indicate that the antibacterial activity of ZnO nanorods is higher towards Gram positive bacterium than Gram negative bacterium which indicates that the structure of the cell wall might play a major role in the interaction with nanostructured materials and shows high sensitivity to the particle concentration. Highlights: ► Effect of ZnO nanorods on the growth cycles of four bacterial strains. ► A relation has been established between growth rate of bacteria and concentration. ► Serious damage in the morphology of bacterial cells in the presence of ZnO nanorods. ► Microscopic studies to see the time dependent effect on bacterial cells

  18. Antibiotic resistance of gram-negative bacilli isolated from pediatric patients with nosocomial bloodstream infections in a Mexican tertiary care hospital.

    Science.gov (United States)

    Ares, Miguel Ángel; Alcántar-Curiel, Maria Dolores; Jiménez-Galicia, César; Rios-Sarabia, Nora; Pacheco, Sabino; De la Cruz, Miguel Ángel

    2013-01-01

    Gram-negative bacilli are the most common bacteria causing nosocomial bloodstream infections (NBSIs) in Latin American countries. The antibiotic resistance profiles of Gram-negative bacilli isolated from blood cultures in pediatric patients with NBSIs over a 3-year period in a tertiary care pediatric hospital in Mexico City were determined using the VITEK-2 system. Sixteen antibiotics were tested to ascertain the resistance rate and the minimum inhibitory concentration using the Clinical Laboratory Standards Institute (CLSI) broth micro-dilution method as a reference. A total of 931 isolates were recovered from 847 clinically significant episodes of NBSI. Of these, 477 (51.2%) were caused by Gram-negative bacilli. The most common Gram-negative bacilli found were Klebsiella pneumoniae (30.4%), Escherichia coli (18.9%), Enterobacter cloacae (15.1%), Pseudomonas aeruginosa (9.9%), and Acinetobacter baumannii (4.6%). More than 45 and 60% of the K. pneumoniae and E. coli isolates, respectively, were resistant to cephalosporins, and 64% of the E. coli isolates were resistant to fluoroquinolones. A. baumannii exhibited low rates of resistance to antibiotics tested. In the E. cloacae and P. aeruginosa isolates, no rates of resistance higher than 38% were observed. In this study, we found that the proportion of NBSIs due to antibiotic-resistant organisms is increasing in a tertiary care pediatric hospital of Mexico.

  19. Different phenotypic and molecular mechanisms associated with multidrug resistance in Gram-negative clinical isolates from Egypt

    Directory of Open Access Journals (Sweden)

    Helmy OM

    2017-12-01

    , accompanied by blaTEM-1, blaCTX-M-15, blaCTX-M-14, aac(6’-Ib-cr, qnrS, and multidrug efflux-mediated resistance.Conclusion: MDR phenotypes are predominant among third-generation cephalosporin-resistant Gram-negative bacteria in Egypt and mediated by different mechanisms, with an increased role of efflux pumps in Enterobacteriaceae. Keywords: multidrug resistance, efflux pump, Egypt, Gram-negative bacilli, RAPD typing

  20. Antibiotic Resistance and Regulation of the Gram-Negative Bacterial Outer Membrane Barrier by Host Innate Immune Molecules

    Directory of Open Access Journals (Sweden)

    Samuel I. Miller

    2016-09-01

    Full Text Available The Gram-negative outer membrane is an important barrier that provides protection against toxic compounds, which include antibiotics and host innate immune molecules such as cationic antimicrobial peptides. Recently, significant research progress has been made in understanding the biogenesis, regulation, and functioning of the outer membrane, including a recent paper from the laboratory of Dr. Brett Finlay at the University of British Columbia (J. van der Heijden et al., mBio 7:e01238-16, 2016, http://dx.doi.org/10.1128/mBio.01541-16. These investigators demonstrate that toxic oxygen radicals, such as those found in host tissues, regulate outer membrane permeability by altering the outer membrane porin protein channels to regulate the influx of oxygen radicals as well as β-lactam antibiotics. This commentary provides context about this interesting paper and discusses the prospects of utilizing increased knowledge of outer membrane biology to develop new antibiotics for antibiotic-resistant Gram-negative bacteria.

  1. Novel insights in preventing Gram-negative bacterial infection in cirrhotic patients: review on the effects of GM-CSF in maintaining homeostasis of the immune system.

    Science.gov (United States)

    Xu, Dong; Zhao, Manzhi; Song, Yuhu; Song, Jianxin; Huang, Yuancheng; Wang, Junshuai

    2015-01-01

    Cirrhotic patients with dysfunctional and/or low numbers of leukocytes are often infected with bacteria, especially Gram-negative bacteria, which is characterized by producing lipopolysaccharide (LPS). Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic cytokine that influences the production, maturation, function, and survival of various immune cells. In this paper, we reviewed not only Toll-like receptors 4 (TLR4) signaling pathway and its immunological effect, but also the specific stimulating function and autocrine performance of GM-CSF on hematopoietic cells, as well as the recent discovery of innate response activator-B cells in protection against microbial sepsis and the direct LPS-TLR4 signaling on hematopoiesis. Thus we concluded that GM-CSF might play important roles in preventing Gram-negative bacterial infections in cirrhotic patients through maintaining immune system functions and homeostasis.

  2. What's on the Outside Matters: The Role of the Extracellular Polymeric Substance of Gram-negative Biofilms in Evading Host Immunity and as a Target for Therapeutic Intervention*

    OpenAIRE

    Gunn, John S.; Bakaletz, Lauren O.; Wozniak, Daniel J.

    2016-01-01

    Biofilms are organized multicellular communities encased in an extracellular polymeric substance (EPS). Biofilm-resident bacteria resist immunity and antimicrobials. The EPS provides structural stability and presents a barrier; however, a complete understanding of how EPS structure relates to biological function is lacking. This review focuses on the EPS of three Gram-negative pathogens: Pseudomonas aeruginosa, nontypeable Haemophilus influenzae, and Salmonella enterica serovar Typhi/Typhimur...

  3. A thermostable Salmonella phage endolysin, Lys68, with broad bactericidal properties against gram-negative pathogens in presence of weak acids.

    Directory of Open Access Journals (Sweden)

    Hugo Oliveira

    Full Text Available Resistance rates are increasing among several problematic Gram-negative pathogens, a fact that has encouraged the development of new antimicrobial agents. This paper characterizes a Salmonella phage endolysin (Lys68 and demonstrates its potential antimicrobial effectiveness when combined with organic acids towards Gram-negative pathogens. Biochemical characterization reveals that Lys68 is more active at pH 7.0, maintaining 76.7% of its activity when stored at 4°C for two months. Thermostability tests showed that Lys68 is only completely inactivated upon exposure to 100°C for 30 min, and circular dichroism analysis demonstrated the ability to refold into its original conformation upon thermal denaturation. It was shown that Lys68 is able to lyse a wide panel of Gram-negative bacteria (13 different species in combination with the outer membrane permeabilizers EDTA, citric and malic acid. While the EDTA/Lys68 combination only inactivated Pseudomonas strains, the use of citric or malic acid broadened Lys68 antibacterial effect to other Gram-negative pathogens (lytic activity against 9 and 11 species, respectively. Particularly against Salmonella Typhimurium LT2, the combinatory effect of malic or citric acid with Lys68 led to approximately 3 to 5 log reductions in bacterial load/CFUs after 2 hours, respectively, and was also able to reduce stationary-phase cells and bacterial biofilms by approximately 1 log. The broad killing capacity of malic/citric acid-Lys68 is explained by the destabilization and major disruptions of the cell outer membrane integrity due to the acidity caused by the organic acids and a relatively high muralytic activity of Lys68 at low pH. Lys68 demonstrates good (thermostability properties that combined with different outer membrane permeabilizers, could become useful to combat Gram-negative pathogens in agricultural, food and medical industry.

  4. A thermostable Salmonella phage endolysin, Lys68, with broad bactericidal properties against gram-negative pathogens in presence of weak acids.

    Science.gov (United States)

    Oliveira, Hugo; Thiagarajan, Viruthachalam; Walmagh, Maarten; Sillankorva, Sanna; Lavigne, Rob; Neves-Petersen, Maria Teresa; Kluskens, Leon D; Azeredo, Joana

    2014-01-01

    Resistance rates are increasing among several problematic Gram-negative pathogens, a fact that has encouraged the development of new antimicrobial agents. This paper characterizes a Salmonella phage endolysin (Lys68) and demonstrates its potential antimicrobial effectiveness when combined with organic acids towards Gram-negative pathogens. Biochemical characterization reveals that Lys68 is more active at pH 7.0, maintaining 76.7% of its activity when stored at 4°C for two months. Thermostability tests showed that Lys68 is only completely inactivated upon exposure to 100°C for 30 min, and circular dichroism analysis demonstrated the ability to refold into its original conformation upon thermal denaturation. It was shown that Lys68 is able to lyse a wide panel of Gram-negative bacteria (13 different species) in combination with the outer membrane permeabilizers EDTA, citric and malic acid. While the EDTA/Lys68 combination only inactivated Pseudomonas strains, the use of citric or malic acid broadened Lys68 antibacterial effect to other Gram-negative pathogens (lytic activity against 9 and 11 species, respectively). Particularly against Salmonella Typhimurium LT2, the combinatory effect of malic or citric acid with Lys68 led to approximately 3 to 5 log reductions in bacterial load/CFUs after 2 hours, respectively, and was also able to reduce stationary-phase cells and bacterial biofilms by approximately 1 log. The broad killing capacity of malic/citric acid-Lys68 is explained by the destabilization and major disruptions of the cell outer membrane integrity due to the acidity caused by the organic acids and a relatively high muralytic activity of Lys68 at low pH. Lys68 demonstrates good (thermo)stability properties that combined with different outer membrane permeabilizers, could become useful to combat Gram-negative pathogens in agricultural, food and medical industry.

  5. Adhesion Properties of Lactic Acid Bacteria on Intestinal Mucin

    Directory of Open Access Journals (Sweden)

    Keita Nishiyama

    2016-09-01

    Full Text Available Lactic acid bacteria (LAB are Gram-positive bacteria that are natural inhabitants of the gastrointestinal (GI tracts of mammals, including humans. Since Mechnikov first proposed that yogurt could prevent intestinal putrefaction and aging, the beneficial effects of LAB have been widely demonstrated. The region between the duodenum and the terminal of the ileum is the primary region colonized by LAB, particularly the Lactobacillus species, and this region is covered by a mucus layer composed mainly of mucin-type glycoproteins. The mucus layer plays a role in protecting the intestinal epithelial cells against damage, but is also considered to be critical for the adhesion of Lactobacillus in the GI tract. Consequently, the adhesion exhibited by lactobacilli on mucin has attracted attention as one of the critical factors contributing to the persistent beneficial effects of Lactobacillus in a constantly changing intestinal environment. Thus, understanding the interactions between Lactobacillus and mucin is crucial for elucidating the survival strategies of LAB in the GI tract. This review highlights the properties of the interactions between Lactobacillus and mucin, while concomitantly considering the structure of the GI tract from a histochemical perspective.

  6. Re-interpretation of the evidence for the PVC cell plan supports a Gram-negative origin.

    Science.gov (United States)

    Devos, Damien P

    2014-02-01

    The PVC superphylum consists of the core phyla Planctomycetes, Verrucomicrobia and Chlamydiae, together with additional ones. Historically, the cell plan of PVC bacteria has been interpreted as an 'exception' to the classical Gram-negative (Gneg) one (Fuerst Antonie van Leeuwenhoek 104:451-466, 2013). However recent genomic and electron-microscopy data have argued against this exceptional status and suggested the need for a reinterpretation of the data in a more classical framework. In this perspective, I evaluate the arguments that have recently been presented by Fuerst as supporting the PVC cell plan as an 'exception' and present an alternative interpretation that is based on proposed evolutionary events that may have shaped the PVC genomes and proteomes. This interpretation supports the alternative proposal that the PVC cell plan is derived from a Gneg one.

  7. Candidatus Renichlamydia lutjani, a Gram-negative bacterium in internal organs of blue striped snapper Lutjanus kasmira from Hawaii

    Science.gov (United States)

    Corsaro, Daniele; Work, Thierry M.

    2012-01-01

    The blue-striped snapper Lutjanus kasmira (Perciformes, Lutjanidae) are cosmopolitan in the Indo-Pacific but were introduced into Oahu, Hawaii, USA, in the 1950s and have since colonized most of the archipelago. Studies of microparasites in blue-striped snappers from Hawaii revealed chlamydia-like organisms (CLO) infecting the spleen and kidney, characterized by intracellular basophilic granular inclusions containing Gram-negative and Gimenez-positive bacteria similar in appearance to epitheliocysts when seen under light microscopy. We provide molecular evidence that CLO are a new member of Chlamydiae, i.e. Candidatus Renichlamydia lutjani, that represents the first reported case of chlamydial infection in organs other than the gill in fishes.

  8. Pyridone Methylsulfone Hydroxamate LpxC Inhibitors for the Treatment of Serious Gram-Negative Infections

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, Justin I.; Brown, Matthew F.; Reilly, Usa; Price, Loren M.; Abramite, Joseph A.; Arcari, Joel; Barham, Rose; Che, Ye; Chen, Jinshan Michael; Chung, Seung Won; Collantes, Elizabeth M.; Desbonnet, Charlene; Doroski, Matthew; Doty, Jonathan; Engtrakul, Juntyma J.; Harris, Thomas M.; Huband, Michael; Knafels, John D.; Leach, Karen L.; Liu, Shenping; Marfat, Anthony; McAllister, Laura; McElroy, Eric; Menard, Carol A.; Mitton-Fry, Mark; Mullins, Lisa; Noe, Mark C.; O’Donnell, John; Oliver, Robert; Penzien, Joseph; Plummer, Mark; Shanmugasundaram, Veerabahu; Thoma, Christy; Tomaras, Andrew P.; Uccello, Daniel P.; Vaz, Alfin; Wishka, Donn G. (Pfizer)

    2012-11-09

    The synthesis and biological activity of a new series of LpxC inhibitors represented by pyridone methylsulfone hydroxamate 2a is presented. Members of this series have improved solubility and free fraction when compared to compounds in the previously described biphenyl methylsulfone hydroxamate series, and they maintain superior Gram-negative antibacterial activity to comparator agents.

  9. Non-oral gram-negative facultative rods in chronic periodontitis microbiota

    NARCIS (Netherlands)

    van Winkelhoff, Arie J; Rurenga, Patrick; Wekema-Mulder, Gepke J; Singadji, Zadnach; Rams, Thomas E

    OBJECTIVE: The subgingival prevalence of gram-negative facultative rods not usually inhabiting or indigenous to the oral cavity (non-oral GNFR), as well as selected periodontal bacterial pathogens, were evaluated by culture in untreated and treated chronic periodontitis patients. METHODS:

  10. Clinical outcomes and safety of colistin in treatment of gram negative infections: A prospective observational study

    Directory of Open Access Journals (Sweden)

    Kinnari Desai

    2016-08-01

    Conclusion: Colistin is effective in treatment of gram negative infections and its use should be reappraised. However since colistin is the last resort it is imperative to make its best use to ensure that it remains as a safe and effective mode of treatment when need be.

  11. Detection of irradiated chicken and fish meats by the determination of Gram negative bacterial count and bacterial endotoxins

    International Nuclear Information System (INIS)

    Badr, H.M.

    2010-01-01

    The aim of this investigation was to study the possibility of detecting irradiated chicken and fish meats by the determination of Gram negative bacteria combined with the determination of endotoxin concentrations. Samples of chicken breast with skin, skinless chicken breast and eviscerated Bolti fish (Tilabia nilotica) were irradiated at room temperature at doses of 0, 1.5 and 3 kGy followed by storage at refrigeration temperature (4 ± 1 degree C) for 12 days or frozen storage at -18 degree C for 60 days. Furthermore, other samples of chicken and Bolti fish were irradiated in the frozen sate at doses of 0, 3, and 7 kGy followed by frozen storage at - 18 degree C for 60 days. Then the enumeration of Gram negative bacteria in conjunction with the determination of endotoxin concentrations were carried out for both irradiated and non-irradiated samples post treatments and during storage in addition to the discovery of Pseudomonas spp. The obtained results showed that chicken and fish samples irradiated at dose of 1.5 kGy could be identified during refrigerated storage for 6 and 9 days, respectively, while all samples irradiated at dose of 3 kGy were identifiable during 12 days of refrigerated storage. Moreover, all irradiated and frozen stored samples were identifiable during their frozen storage (- 18 degree C). The absence of Pseudomonads in all irradiated samples may aid in the differentiation of irradiated and non-irradiated samples especially during refrigerated storage. This method can be applied as a general screening method to predict the possible treatment of chicken and fish meats by ionizing radiation

  12. Organo-Selenium Coatings Inhibit Gram-Negative and Gram-Positive Bacterial Attachment to Ophthalmic Scleral Buckle Material.

    Science.gov (United States)

    Tran, Phat; Arnett, Avery; Jarvis, Courtney; Mosley, Thomas; Tran, Khien; Hanes, Rob; Webster, Dan; Mitchell, Kelly; Dominguez, Leo; Hamood, Abdul; Reid, Ted W

    2017-09-01

    Biofilm formation is a problem for solid and sponge-type scleral buckles. This can lead to complications that require removal of the buckle, and result in vision loss due to related ocular morbidity, primarily infection, or recurrent retinal detachment. We investigate the ability of a covalent organo-selenium coating to inhibit biofilm formation on a scleral buckle. Sponge and solid Labtican brand scleral buckles were coated with organo-selenium coupled to a silyation reagent. Staphylococcus aureus biofilm formation was monitored by a standard colony-forming unit assay and the confocal laser scanning microscopy, while Pseudomonas aeruginosa biofilm formation was examined by scanning electron microscopy. Stability studies were done, by soaking in phosphate buffer saline (PBS) at room temperature for 2 months. Toxicity against human corneal epithelial cell was examined by growing the cells in the presence of organo-selenium-coated scleral buckles. The organo-selenium coating inhibited biofilm formation by gram-negative and gram-positive bacteria. The buckle coatings also were shown to be fully active after soaking in PBS for 2 months. The organo-selenium coatings had no effect on the viability of human corneal epithelial cells. Organo-selenium can be used to covalently coat a scleral buckle, which is stable and inhibits biofilm formation for gram-negative and gram-positive bacteria. The organo-selenium buckle coating was stable and nontoxic to cell culture. This technology provides a means to inhibit bacterial attachment to devices attached to the eye, without damage to ocular cells.

  13. Effectiveness of oral antibiotics for definitive therapy of Gram-negative bloodstream infections.

    Science.gov (United States)

    Kutob, Leila F; Justo, Julie Ann; Bookstaver, P Brandon; Kohn, Joseph; Albrecht, Helmut; Al-Hasan, Majdi N

    2016-11-01

    There is paucity of data evaluating intravenous-to-oral antibiotic switch options for Gram-negative bloodstream infections (BSIs). This retrospective cohort study examined the effectiveness of oral antibiotics for definitive treatment of Gram-negative BSI. Patients with Gram-negative BSI hospitalised for antibiotics were included in this study. The cohort was stratified into three groups based on bioavailability of oral antibiotics prescribed (high, ≥95%; moderate, 75-94%; and low, antibiotics were prescribed to 106, 179 and 77 patients, respectively, for definitive therapy of Gram-negative BSI. Mean patient age was 63 years, 217 (59.9%) were women and 254 (70.2%) had a urinary source of infection. Treatment failure rates were 2%, 12% and 14% in patients receiving oral antibiotics with high, moderate and low bioavailability, respectively (P = 0.02). Risk of treatment failure in the multivariate Cox model was higher in patients receiving antibiotics with moderate [adjusted hazard ratio (aHR) = 5.9, 95% CI 1.6-38.5; P = 0.005] and low bioavailability (aHR = 7.7, 95% CI 1.9-51.5; P = 0.003) compared with those receiving oral antimicrobial agents with high bioavailability. These data demonstrate the effectiveness of oral antibiotics with high bioavailability for definitive therapy of Gram-negative BSI. Risk of treatment failure increases as bioavailability of the oral regimen declines. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  14. Relationship between Gram negative enteric rods, Aggregatibacter actinomycetemcomitans, and clinical parameters in periodontal disease

    Directory of Open Access Journals (Sweden)

    Carlos M Ardila

    2012-01-01

    Full Text Available Background: The association between Gram negative enteric rods and Aggregatibacter actinomycetemcomitans in periodontal diseases has received little attention in the literature. The objective of this study was to explore the relationship between these organisms and clinical parameters of periodontal disease. Materials and Methods: Clinical parameters and occurrence of Gram-negative enteric rods and A. actinomycetemcomitans were examined in 76 patients with chronic periodontitis. Chi-square and Mann-Whitney tests were used to determine differences in clinical variables versus the presence or absence of both microorganisms. Correlation among both organisms and clinical data were determined using Spearman rank correlation coefficient. Results: Gram-negative enteric rods and A. actinomycetemcomitans were detected in 20 (26.3% and 18 (23.7% individuals, respectively. A total of 14 (18.4% patients harbored both microorganisms studied. There were significantly positive correlations between enteric rods and presence of A. actinomycetemcomitans (r=0.652, P<0.0001. Both microorganisms were significant and positively correlated with probing depth (PD, clinical attachment level, and bleeding on probing (P<0.0001. The mean PD (mm of the sampled sites was significantly deeper in patients with presence of A. actinomycetemcomitans and Gram-negative enteric rods. Conclusion: The results of the present study suggest a strong positive correlation between Gram-negative enteric rods and A. actinomycetemcomitans in the population studied. This finding must be taken into account when considering the best therapeutic approach, including the utilization of antimicrobials. The adverse clinical outcomes observed in presence of these microorganisms could have implications in the pathogenesis of periodontal disease and a possible impact on outcomes after treatment.

  15. A Thermostable Salmonella Phage Endolysin, Lys68, with Broad Bactericidal Properties against Gram-Negative Pathogens in Presence of Weak Acids

    DEFF Research Database (Denmark)

    Oliveira, Hugo; Thiagarajan, Viruthachalam; Walmagh, Maarten

    2014-01-01

    , and circular dichroism analysis demonstrated the ability to refold into its original conformation upon thermal denaturation. It was shown that Lys68 is able to lyse a wide panel of Gram-negative bacteria (13 different species) in combination with the outer membrane permeabilizers EDTA, citric and malic acid....... While the EDTA/Lys68 combination only inactivated Pseudomonas strains, the use of citric or malic acid broadened Lys68 antibacterial effect to other Gram-negative pathogens (lytic activity against 9 and 11 species, respectively). Particularly against Salmonella Typhimurium LT2, the combinatory effect...... of malic or citric acid with Lys68 led to approximately 3 to 5 log reductions in bacterial load/CFUs after 2 hours, respectively, and was also able to reduce stationary-phase cells and bacterial biofilms by approximately 1 log. The broad killing capacity of malic/citric acid-Lys68 is explained...

  16. An evaluation of the New Roche Diagnostics Kit for the rapid identification of clinically important non-dextrose, non-fastidious gram-negative rods.

    Science.gov (United States)

    Elegbe, I A

    1980-01-01

    The evaluation of the new Roche Diagnostics Commercial kit (Roche Diagnostics, 1975) for the identification of non-dextrose fermenting, non-fastidious gram-negative rods has been compared with conventional methods in the recognition and identification of these non-dextrose, non-fastidious gram-negative bacteria. This new kit has definite advantages over and above the conventional methods in a number of ways. It is cheaper to run, and above all it is less cumbersome, less time consuming and it is accurate. Apart from all these, the new method makes use of the odour test (Roche Diagnostics, 1975) and other additional conventional tests recommended by the Oxi/ferm manufacturer.

  17. [Identification of anaerobic gram-negative bacilli isolated from various clinical specimens and determination of antibiotic resistance profiles with E-test methods].

    Science.gov (United States)

    Demir, Cengiz; Keşli, Recep

    2018-01-01

    The aim of this study was to identify gram-negative anaerobic bacilli isolated from various clinical specimens that were obtained from patients with suspected anaerobic infections and to determine the antibiotic resistance profiles by using the antibiotic concentration gradient method. The study was performed in Afyon Kocatepe University Ahmet Necdet Sezer Research and Practice Hospital, Medical Microbiology Laboratory between 1 November 2014 and 30 October 2015. Two hundred and seventyeight clinical specimens accepted for anaerobic culture were enrolled in the study. All the samples were cultivated anaerobically by using Schaedler agar with 5% defibrinated sheep blood and Schaedler broth. The isolated anaerobic gram-negative bacilli were identified by using both the conventional methods and automated identification system (VITEK 2, bioMerieux, France). Antibiotic susceptibility tests were performed with antibiotic concentration gradient method (E-test, bioMerieux, France); against penicillin G, clindamycin, cefoxitin, metronidazole, moxifloxacin, imipenem, meropenem, ertapenem and doripenem for each isolate. Of the 28 isolated anaerobic gram-negative bacilli; 14 were identified as Bacteroides fragilis group, 9 were Prevotella spp., and 5 were Fusobacterium spp. The highest resistance rate was found against penicillin (78.5%) and resistance rates against clindamycin and cefoxitin were found as 17.8% and 21.4%, respectively. No resistance was found against metronidazole, moxifloxacin, imipenem, meropenem, ertapenem and doripenem. As a result, isolation and identification of anaerobic bacteria are difficult, time-consuming and more expensive when compared with the cost of aerobic culture. The rate of anaerobic bacteria isolation may be increased by obtaining the appropriate clinical specimen and appropriate transportation of these specimens. We believe that the data obtained from the study in our center may offer benefits for the follow up and treatment of infections

  18. Presence and antimicrobial profile of gram-negative facultative anaerobe rods in patients with chronic periodontitis and gingivitis.

    Science.gov (United States)

    Gamboa, Fredy; García, Dabeiba-Adriana; Acosta, Adriana; Mizrahi, Deborah; Paz, Andreína; Martínez, Diana; Arévalo, Azucena; Aristizabal, Fabio; Abba, Martín

    2013-01-01

    Chronic periodontitis is a multifactorial infectious disease associated with Gram-negative anaerobes which are part of the subgingival microflora. In recent years, studies have been conducted to assess the presence of Gram-negative facultative anaerobes (Enterobacteriaceae) and their participation in the development and progression of chronic periodontitis. The aim of this study was to determine the presence of Enterobacteriaceae in patients with chronic periodontitis and gingivitis and to assess antimicrobial susceptibility of clinical isolates. A descriptive, observational study was performed including 64 patients with chronic periodontitis and 22 patients with gingivitis. Microbiological samples were taken from the gingival sulcus using paper points, which then were placed in thioglycollate broth. Samples were incubated for 4 hours at 37 degrees C and finally replated on MacConkey agar Bacteria were identified using the API-20E system (Biomerieux, France) and antimicrobial susceptibility was determined using the disk diffusion method. The evaluation of samples showed presence of 29 enterobacterial species distributed as follows: 7 in the group with gingivitis and 22 in the group with chronic periodontitis. In the chronic periodontitis group the most common species were: K. oxytoca n = 5, S. liquefaciens n = 4 and K. pneumoniae and E. coli with n = 3. The gingivitis group had the highest frequency of Erwinia sp. (n = 2). Clinical isolates showed very low sensitivity levels to beta-lactam ampicillin and amoxicillin/ clavulanic acid, 17.2% and 27.6% respectively, and higher sensitivity levels to ciprofloxacin (96.6%), amikacin (79.3%), gentamicin (68.9%) and ceftazidime, ceftriaxone, kanamycin and trimethoprimsulfa (65.5%). In conclusion, the existence of a high frequency of enterobacteria in patients with chronic periodontitis and gingivitis shows that periodontologists should pay greater attention to prevention protocols, and develop mechanical and antimicrobial

  19. The Influence of Efflux Pump Inhibitors on the Activity of Non-Antibiotic NSAIDS against Gram-Negative Rods.

    Directory of Open Access Journals (Sweden)

    Agnieszka E Laudy

    Full Text Available Most patients with bacterial infections suffer from fever and various pains that require complex treatments with antibiotics, antipyretics, and analgaesics. The most common drugs used to relieve these symptoms are non-steroidal anti-inflammatory drugs (NSAIDs, which are not typically considered antibiotics. Here, we investigate the effects of NSAIDs on bacterial susceptibility to antibiotics and the modulation of bacterial efflux pumps.The activity of 12 NSAID active substances, paracetamol (acetaminophen, and eight relevant medicinal products was analyzed with or without pump inhibitors against 89 strains of Gram-negative rods by determining the MICs. Furthermore, the effects of NSAIDs on the susceptibility of clinical strains to antimicrobial agents with or without PAβN (Phe-Arg-β-naphtylamide were measured.The MICs of diclofenac, mefenamic acid, ibuprofen, and naproxen, in the presence of PAβN, were significantly (≥4-fold reduced, decreasing to 25-1600 mg/L, against the majority of the studied strains. In the case of acetylsalicylic acid only for 5 and 7 out of 12 strains of P. mirabilis and E. coli, respectively, a 4-fold increase in susceptibility in the presence of PAβN was observed. The presence of Aspirin resulted in a 4-fold increase in the MIC of ofloxacin against only two strains of E. coli among 48 tested clinical strains, which included species such as E. coli, K. pneumoniae, P. aeruginosa, and S. maltophilia. Besides, the medicinal products containing the following NSAIDs, diclofenac, mefenamic acid, ibuprofen, and naproxen, did not cause the decrease of clinical strains' susceptibility to antibiotics.The effects of PAβN on the susceptibility of bacteria to NSAIDs indicate that some NSAIDs are substrates for efflux pumps in Gram-negative rods. Morever, Aspirin probably induced efflux-mediated resistance to fluoroquinolones in a few E. coli strains.

  20. Exploring the hidden potential of fosfomycin for the fight against severe Gram-negative infections.

    Science.gov (United States)

    Saiprasad, P V; Krishnaprasad, K

    2016-01-01

    Gram-negative resistance is a serious global crisis putting the world on the cusp of 'pre-antibiotic era'. This serious crisis has been catalysed by the rapid increase in carbapenem-resistant Enterobacteriaceae (CRE). Spurge in colistin usage to combat CRE infections leads to the reports of (colistin and carbapenem resistant enterobacteriaceae) CCRE (resistance to colistin in isolates of CRE) infections further jeopardising our last defence. The antibacterial apocalypse imposed by global resistance crisis requires urgent alternative therapeutic options. Interest in the use of fosfomycin renewed recently for serious systemic infections caused by multidrug-resistant Enterobacteriaceae. This review aimed at analysing the recent evidence on intravenous fosfomycin to explore its hidden potential, especially when fosfomycin disodium is going to be available in India. Although a number of promising evidence are coming up for fosfomycin, there are still areas where more work is required to establish intravenous fosfomycin as the last resort antibacterial for severe Gram-negative infections.

  1. Tachypleus lysate test for endotoxin in patients with Gram negative bacterial infections.

    Science.gov (United States)

    Usawattanakul, W; Tharavanij, S; Limsuwan, A

    1979-03-01

    Amoebocyte lysate from the horseshoe crabs (Tachypleus gigas) which abounds in the Gulf of Thailand was used to detect endotoxin in patients with Gram-negative bacteremia, in patients with Gram-positive bacterial infections as well as in the control. The Tachypleus lysate test (TLT) was positive in 94.4% of 36 patients with Gram-negative bacteremia before initiation of antibiotic therapy. Only 4% of 50 healthy individuals were positive and all 7 patients with Gram-positive bacterial infections were negative. The threshold sensitivity of TLT was 0.625 micrograms endotoxin per ml of the plasma. In comparison with the commercial Limulus lysate test (LLT), the TLT was slightly more sensitive in exhibiting higher grade of reaction, eventhough the threshold sensitivity was the same.

  2. Molecular studies on bacteriophage endolysins and their potential to control gram-negative bacteria

    OpenAIRE

    Oliveira, Hugo Alexandre Mendes

    2014-01-01

    Thesis for PhD degree in Chemical and Biological Engineeering Bacteriophages are viruses that specifically infect bacterial hosts to reproduce. At the end of the infection cycle, progeny virions are confronted with a rigid cell wall that impedes their release into the environment. Consequently, bacteriophages encode hydrolytic enzymes, called endolysins, to digest the peptidoglycan and cause bacteriolysis. In contrast to their extensively studied counterparts, active against Gram-positi...

  3. Metallo-beta-lactamases in Gram-negative bacteria: introducing the era of pan-resistance?

    Science.gov (United States)

    Maltezou, Helen C

    2009-05-01

    Metallo-beta-lactamases (MBLs) are being reported with increasing frequency and from several countries worldwide and are becoming the prevalent and most clinically significant determinants of carbapenem resistance. Furthermore, MBL-producing strains that exhibit a pan-resistant phenotype are increasingly detected. Initially MBLs were detected in Pseudomonas aeruginosa, however nowadays they are frequently found in Acinetobacter baumannii, Klebsiella pneumoniae and other Enterobacteriaceae. MBLs spread easily on plasmids and cause nosocomial infections and outbreaks with excess mortality. Such infections mainly concern patients admitted to Intensive Care Units with several co-morbidities and a history of prolonged administration of antibiotics. MBL-producing strains exhibit resistance to almost all currently available antibiotics. In vitro studies reveal that tigecycline and colistin are the only antibacterial agents with consistent activity against MBL-producing strains. Randomised controlled trials are required in order to evaluate the available therapeutic regimens, including treatment combinations. Tigecycline and colistin should be used under appropriate prescribing practices. Surveillance to monitor the emergence of resistance to these agents as well as implementation of infection control measures should be strengthened. MBL inhibitors are urgently needed, however, none is in late pre-clinical development.

  4. The bovine acute phase response to endotoxin and Gram-negative bacteria

    DEFF Research Database (Denmark)

    Jacobsen, Stine

    -induced anorexia and ruminal hypomotility may be detrimental for lactating dairy cows, since these cows are highly dependent on continuous feed intake to avoid severe metabolic disturbances. Furthermore, depression of the cytokine-producing capacity of circulating PBMCs may result in aberrant innate immune...... not undermine this concept as such, but given the significant individual variation in APP response, caution is certainly warranted when absolute concentrations of SAA and haptoglobin are used to interpret disease status in individual cows. In the experimental mastitis model, SAA concentrations in plasma...

  5. Genome-wide protein localization prediction strategies for gram negative bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Romine, Margaret F.

    2011-06-15

    Genome-wide prediction of protein subcellular localization is an important type of evidence used for inferring protein function. While a variety of computational tools have been developed for this purpose, errors in the gene models and use of protein sorting signals that are not recognized by the more commonly accepted tools can diminish the accuracy of their output. As part of an effort to manually curate the annotations of 19 strains of Shewanella, numerous insights were gained regarding the use of computational tools and proteomics data to predict protein localization. Identification of the suite of secretion systems present in each strain at the start of the process made it possible to tailor-fit the subsequent localization prediction strategies to each strain for improved accuracy. Comparisons of the computational predictions among orthologous proteins revealed inconsistencies in the computational outputs, which could often be resolved by adjusting the gene models or ortholog group memberships. While proteomic data was useful for verifying start site predictions and post-translational proteolytic cleavage, care was needed to distinguish cellular versus sample processing-mediated cleavage events. Searches for lipoprotein signal peptides revealed that neither TatP nor LipoP are designed for identification of lipoprotein substrates of the twin arginine translocation system and that the +2 rule for lipoprotein sorting does not apply to this Genus. Analysis of the relationships between domain occurrence and protein localization prediction enabled identification of numerous location-informative domains which could then be used to refine or increase confidence in location predictions. This collective knowledge was used to develop a general strategy for predicting protein localization that could be adapted to other organisms.

  6. Genome-wide protein localization prediction strategies for gram negative bacteria

    Directory of Open Access Journals (Sweden)

    Romine Margaret F

    2011-06-01

    Full Text Available Abstract Background Genome-wide prediction of protein subcellular localization is an important type of evidence used for inferring protein function. While a variety of computational tools have been developed for this purpose, errors in the gene models and use of protein sorting signals that are not recognized by the more commonly accepted tools can diminish the accuracy of their output. Results As part of an effort to manually curate the annotations of 19 strains of Shewanella, numerous insights were gained regarding the use of computational tools and proteomics data to predict protein localization. Identification of the suite of secretion systems present in each strain at the start of the process made it possible to tailor-fit the subsequent localization prediction strategies to each strain for improved accuracy. Comparisons of the computational predictions among orthologous proteins revealed inconsistencies in the computational outputs, which could often be resolved by adjusting the gene models or ortholog group memberships. While proteomic data was useful for verifying start site predictions and post-translational proteolytic cleavage, care was needed to distinguish cellular versus sample processing-mediated cleavage events. Searches for lipoprotein signal peptides revealed that neither TatP nor LipoP are designed for identification of lipoprotein substrates of the twin arginine translocation system and that the +2 rule for lipoprotein sorting does not apply to this Genus. Analysis of the relationships between domain occurrence and protein localization prediction enabled identification of numerous location-informative domains which could then be used to refine or increase confidence in location predictions. This collective knowledge was used to develop a general strategy for predicting protein localization that could be adapted to other organisms. Conclusion Improved localization prediction accuracy is not simply a matter of developing better computational algorithms. It also entails gathering key knowledge regarding the host architecture and translocation machinery and associated substrate recognition via experimentation and integration of diverse computational analyses from many proteins and, where possible, that are derived from different species within the same genus.

  7. Genome-wide protein localization prediction strategies for gram negative bacteria

    Science.gov (United States)

    2011-01-01

    Background Genome-wide prediction of protein subcellular localization is an important type of evidence used for inferring protein function. While a variety of computational tools have been developed for this purpose, errors in the gene models and use of protein sorting signals that are not recognized by the more commonly accepted tools can diminish the accuracy of their output. Results As part of an effort to manually curate the annotations of 19 strains of Shewanella, numerous insights were gained regarding the use of computational tools and proteomics data to predict protein localization. Identification of the suite of secretion systems present in each strain at the start of the process made it possible to tailor-fit the subsequent localization prediction strategies to each strain for improved accuracy. Comparisons of the computational predictions among orthologous proteins revealed inconsistencies in the computational outputs, which could often be resolved by adjusting the gene models or ortholog group memberships. While proteomic data was useful for verifying start site predictions and post-translational proteolytic cleavage, care was needed to distinguish cellular versus sample processing-mediated cleavage events. Searches for lipoprotein signal peptides revealed that neither TatP nor LipoP are designed for identification of lipoprotein substrates of the twin arginine translocation system and that the +2 rule for lipoprotein sorting does not apply to this Genus. Analysis of the relationships between domain occurrence and protein localization prediction enabled identification of numerous location-informative domains which could then be used to refine or increase confidence in location predictions. This collective knowledge was used to develop a general strategy for predicting protein localization that could be adapted to other organisms. Conclusion Improved localization prediction accuracy is not simply a matter of developing better computational algorithms. It also entails gathering key knowledge regarding the host architecture and translocation machinery and associated substrate recognition via experimentation and integration of diverse computational analyses from many proteins and, where possible, that are derived from different species within the same genus. PMID:21810203

  8. Loss of outer membrane integrity in Gram-negative bacteria by silver ...

    Indian Academy of Sciences (India)

    New generation antimicrobial and smart drugs are the needs of the present era in fighting microbial infection and various chronic diseases. Nowadays nanoparticles (NPs) are widely applied in biomedical fields by virtue of their surface modification, which enhances both target selectivity and function. This study is a ...

  9. Characterizations and performance evaluations of thin film interdigital sensors for Gram-negative bacteria detection

    KAUST Repository

    Mohd. Syaifudin, A. R.

    2011-11-01

    Thin film interdigital sensors have been designed and fabricated. The sensors were fabricated using different substrates and using different fabrication technology. The initial design was fabricated on glass slide and fabricated using IDT (Intergrated Device Technology). The new sensors were fabricated on silicon/silicon dioxide wafer. All sensors were coated with APTES, a cross-linker bind to certain bio-molecules and then were immobilized with Polymyxin B, a specific bio-molecules that bind to endotoxin (Lipopolysaccharide, LPS). Sensors were tested for different concentrations of LPS. The impedance characteristics were presented using Impedance Spectroscopy method. A principle component analysis (PCA) was used for better data classification method. © 2011 IEEE.

  10. Loss of outer membrane integrity in Gram-negative bacteria by silver ...

    Indian Academy of Sciences (India)

    negative organisms (Goswami et al, 2015). Silver NPs were synthesized using tea leaves (Camellia sinensis) decoction and were characterized ... strated on account of NP treatment. The particles demonstrated good biocompatibility. ..... Healthy patients were selected as donors who had no history of smoking, obesity and ...

  11. Systems and methods for the secretion of recombinant proteins in gram negative bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Withers, III, Sydnor T.; Dominguez, Miguel A.; DeLisa, Matthew P.; Haitjema, Charles H.

    2017-02-21

    Disclosed herein are systems and methods for producing recombinant proteins utilizing mutant E. coli strains containing expression vectors carrying nucleic acids encoding the proteins, and secretory signal sequences to direct the secretion of the proteins to the culture medium. Host cells transformed with the expression vectors are also provided.

  12. Colistin resistance in gram-negative bacteria during prophylactic topical colistin use in intensive care units

    NARCIS (Netherlands)

    Oostdijk, Evelien A. N.; Smits, Loek; de Smet, Anne Marie G. A.; Leverstein-van Hall, Maurine A.; Kesecioglu, Jozef; Bonten, Marc J. M.

    Topical use of colistin as part of selective digestive decontamination (SDD) and selective oropharyngeal decontamination (SOD) has been associated with improved patient outcome in intensive care units (ICU), yet little is known about the risks of colistin resistance. We quantified effects of

  13. Metallo beta lactamase mediated resistance in Carbapenem resistant gram-negative bacilli: A cause for concern

    Directory of Open Access Journals (Sweden)

    Malini Jagannatha Rao, Shruti A Harle, Padmavathy M, Umapathy BL, Navaneeth BV

    2014-04-01

    Full Text Available Introduction: The emergence of acquired metallo-β-lactamases (MBL in Gram-negative bacilli is becoming a therapeutic challenge, as these enzymes usually possess a broad hydrolysis profile that includes carbapenems, extended-spectrum β-lactams. Aim: To detect Extended spectrum β-lactamases and metallo-β-lactamase in carbapenem resistant Gram negative clinical isolates from various clinical specimens and to evaluate their antibiotic susceptibility patterns. Material and Methods: A total of 100 non duplicates imipenem resistant isolates were tested for the presence of extended spectrum β-lactamases by phenotypic confirmatory test, metallo-β-lactamases by Double disk synergy test with various distances from edge to edge (10mm,15mm,20mm, between the IPM and EDTA and combined disc test. Result: Of the 100 IMP resistant isolates screened 30 (30% were MBL positive by phenotypic methods, i.e., double disk synergy test and combined disc test. Co-existence of Extended spectrum β-lactamases and MBL were detected in 3 (30%. All the 30 MBL positive isolates had shown synergy at (100% at 10 mm distance, 27 (90% isolates had shown synergy at 15 mm distance and 13 (43.4% isolates were shown synergy at 20 mm distance. All the 30 MBLs producers were multidrug resistant and 27 (90% were sensitive to colistin (CL. All MBL positive Pseudomonas aeruginosa were sensitive to polymyxin B (100µg. Conclusion: Microbiologists are now facing a challenge of drug resistance due to MBL production. Although CLSI guidelines do not quote about the ESBL detection in Pseudomonas aeruginosa MBLs and ESBL have to be detected in them. The use of combination tests would increase the sensitivity to detect the presence of MBL among the clinical isolates of Gram-negative bacilli. The spread of MBL producing Gram negative organism can be prevented if they are detected in all isolates and routinely adopted in all laboratories.

  14. Antimicrobial consumption and resistance in five Gram-negative bacterial species in a hospital from 2003 to 2011.

    Science.gov (United States)

    Lee, Heng-Sim; Loh, Yue-Xia; Lee, Jen-Jain; Liu, Chang-Shee; Chu, Chishih

    2015-12-01

    The misuse of antimicrobial agents increases drug resistance in bacteria. The correlation between antimicrobial agent consumption and related resistance in the Gram-negative bacteria Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Proteus mirabilis was analyzed during the period 2003-2011. Among these five bacteria, overall E. coli and K. pneumoniae were more commonly isolated from bloodstream than the other species. Regarding Enterobacteriaceae, E. coli and K. pneumoniae showed annual increases of resistance to the tested antimicrobial agents; conversely, P. mirabilis exhibited reduced resistance to cefuroxime, ceftriaxone and cefepime. In contrast to the relatively low antimicrobial resistance in P. aeruginosa, A. baumannii revealed high resistance, which was over 85% resistant rate to the tested antimicrobial agents and over 80% carbapenem resistance in 2011. E. coli, K. pneumoniae, and P. mirabilis differed in development of antimicrobial resistance after consumption of the antimicrobial agents. K. pneumoniae developed resistance to all antimicrobial groups, whereas resistance in P. mirabilis was not related to any antimicrobial consumption. P. aeruginosa developed resistance to β-lactam antimicrobials and aminoglycosides, whereas A. baumanii developed resistance to carbapenems after their use. The development of antimicrobial resistance was related to antimicrobial agents and bacterial species. Copyright © 2014. Published by Elsevier B.V.

  15. Prognostic factors and monomicrobial necrotizing fasciitis: gram-positive versus gram-negative pathogens

    Directory of Open Access Journals (Sweden)

    Hsu Wei-Hsiu

    2011-01-01

    Full Text Available Abstract Background Monomicrobial necrotizing fasciitis is rapidly progressive and life-threatening. This study was undertaken to ascertain whether the clinical presentation and outcome for patients with this disease differ for those infected with a gram-positive as compared to gram-negative pathogen. Methods Forty-six patients with monomicrobial necrotizing fasciitis were examined retrospectively from November 2002 to January 2008. All patients received adequate broad-spectrum antibiotic therapy, aggressive resuscitation, prompt radical debridement and adjuvant hyperbaric oxygen therapy. Eleven patients were infected with a gram-positive pathogen (Group 1 and 35 patients with a gram-negative pathogen (Group 2. Results Group 2 was characterized by a higher incidence of hemorrhagic bullae and septic shock, higher APACHE II scores at 24 h post-admission, a higher rate of thrombocytopenia, and a higher prevalence of chronic liver dysfunction. Gouty arthritis was more prevalent in Group 1. For non-survivors, the incidences of chronic liver dysfunction, chronic renal failure and thrombocytopenia were higher in comparison with those for survivors. Lower level of serum albumin was also demonstrated in the non-survivors as compared to those in survivors. Conclusions Pre-existing chronic liver dysfunction, chronic renal failure, thrombocytopenia and hypoalbuminemia, and post-operative dependence on mechanical ventilation represent poor prognostic factors in monomicrobial necrotizing fasciitis. Patients with gram-negative monobacterial necrotizing fasciitis present with more fulminant sepsis.

  16. DMPD: Gram-negative endotoxin: an extraordinary lipid with profound effects oneukaryotic signal transduction. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 1916089 Gram-negative endotoxin: an extraordinary lipid with profound effects oneuk...ep;5(12):2652-60. (.png) (.svg) (.html) (.csml) Show Gram-negative endotoxin: an extraordinary lipid with pr...tive endotoxin: an extraordinary lipid with profound effects oneukaryotic signal transduction. Authors Raetz

  17. Fate and Enumeration Problems of Fecal Coliform Bacteria in Runoff Waters from Terrestrial Ecosystems.

    Science.gov (United States)

    1980-09-01

    1914. Thus, total coliform tests, which enumerate coliform bacteria that grow at 35*C, were developed. European researchers were * Gram-negative...compared with the enteric virus, Poliovirus 1. Removal effi- ciencies for the coliphage and enterovirus ranged from 30 to 60 percent and 65 to 85...selective for an obligate microorganism of the intestinal tract of most warm- blooded animals, namely, E. coli. However, other bacteria can grow and

  18. Cefepime restriction improves gram-negative overall resistance patterns in neonatal intensive care unit

    Directory of Open Access Journals (Sweden)

    Orlei Ribeiro de Araujo

    Full Text Available Antibiotic restriction can be useful in maintaining bacterial susceptibility. The objective of this study was verify if restriction of cefepime, the most frequently used cephalosporin in our neonatal intensive care unit (NICU, would ameliorate broad-spectrum susceptibility of Gram-negative isolates. Nine hundred and ninety-five premature and term newborns were divided into 3 cohorts, according to the prevalence of cefepime use in the unit: Group 1 (n=396 comprised patients admitted from January 2002 to December 2003, period in which cefepime was the most used broad-spectrum antibiotic. Patients in Group 2 (n=349 were admitted when piperacillin/tazobactam replaced cefepime (January to December 2004 and in Group 3 (n=250 when cefepime was reintroduced (January to September 2005. Meropenem was the alternative third-line antibiotic for all groups. Multiresistance was defined as resistance to 2 or more unrelated antibiotics, including necessarily a third or fourth generation cephalosporin, piperacillin/tazobactam or meropenem. Statistics involved Kruskal-Wallis, Mann-Whitney and logrank tests, Kaplan-Meier analysis. Groups were comparable in length of stay, time of mechanical ventilation, gestational age and birth weight. Ninety-eight Gram-negative isolates were analyzed. Patients were more likely to remain free of multiresistant isolates by Kaplan-Meier analysis in Group 2 when compared to Group 1 (p=0.017 and Group 3 (p=0.003. There was also a significant difference in meropenem resistance rates. Cefepime has a greater propensity to select multiresistant Gram-negative pathogens than piperacillin/tazobactam and should not be used extensively in neonatal intensive care.

  19. Prevalence of Gram-negative Pathogens and their antimicrobial susceptibility in bacterial meningitis in pediatric cases

    Directory of Open Access Journals (Sweden)

    Yash Pal Chugh

    2012-07-01

    Full Text Available The present study was conducted to find out the prevalence and spectrum of Gram negative pathogens causing bacterial meningitis and their antimicrobial susceptibility pattern in a tertiary care hospital. The cerebrospinal fluid (CSF (3-5 ml was collected from 638 admitted children clinically suspected of septic meningitis. Bacterial isolates were identified and antimicrobial susceptibility was assessed by the Kirby-Bauer disk diffusion method. Of the 638 samples tested 102 (15.99% were culture positive. Male to female (M:F ratio was 1.62:1. The maximum incidence of 45 (44.12% cases was found in children (1-12 yrs; in institutional deliveries the incidence was 58 (56.86% cases. Further, the incidence of 51 cases was found from May to August. Escherichia coli (E. coli were commonest, seen in 9 (25% cases followed by Acinetobacter spp., Citrobacter spp. and Klebsiella spp. with 6 (16.67% cases each. Enterobacter spp., Neisseria spp. and Pseudomonas aeruginosa were isolated in 3 (8.33% cases each. E. coli, Acinetobacter spp, Citrobacter spp and Klebsiella spp isolates were 100% susceptible to meropenem, piperacillin-tazobactam and cefoperazone-sulbactam and 100% resistant to cotrimoxazole and tetracycline. All strains of Neisseria spp, Enterobacter spp and Pseudomonas spp. were 100% susceptible to meropenem followed by gatifloxacin. These were 100% resistant to tetracycline and cotrimoxazole. Neisseria spp. were also 100% susceptible to pristinamycin. In septic meningitis Gram negative organisms are less common (35.29%. Of the isolates, more common Gram negative isolates included E. coli, Acinetobacter Spp., Citrobacter Spp., and Klebsiella spp. and these isolates were 100% susceptible to meropenem, piperacillin-tazobacatam and cefoperazone-sulbactam. Hence, empirical therapy should be formulated according to antimicrobial susceptibility patterns.

  20. Prevalence and Characterization of Multi-Drug-Resistant Gram-Negative Bacilli Isolated From Lebanese Poultry: A Nationwide Study

    Directory of Open Access Journals (Sweden)

    Iman Dandachi

    2018-03-01

    Full Text Available Currently, antimicrobial resistance is one of the most prominent public health issues. In fact, there is increasing evidence that animals constitute a reservoir of antimicrobial resistance. In collaboration with the Lebanese Ministry of Agriculture, the aim of this study was to determine the prevalence of intestinal carriage of multi-drug-resistant Gram-negative Bacilli in poultry farms at the national level. Between August and December 2015, 981 fecal swabs were obtained from 49 poultry farms distributed across Lebanon. The swabs were subcultured on MacConkey agar supplemented with cefotaxime (2 μg/ml. Isolated strains were identified using MALDI-TOF mass spectrometry. Multilocus sequence typing analysis was performed for Escherichia coli. Phenotypic detection of extended spectrum β-lactamases (ESBL and AmpC production was performed using double disk synergy and the ampC disk test, respectively. β-lactamase encoding genes blaCTX-M, blaTEM, blaSHV, blaFOX, blaMOX, blaEBC, blaACC, blaDHA, and blaCMY using PCR amplification. Out of 981 fecal swabs obtained, 203 (20.6% showed bacterial growth on the selective medium. Of the 235 strains isolated, 217 were identified as E. coli (92%, eight as Klebsiella pneumoniae (3%, three as Proteus mirabilis (1% and three as Enterobacter cloacae (1%. MLST analysis of E. coli isolates showed the presence of ST156, ST5470, ST354, ST155, and ST3224. The phenotypic tests revealed that 43.5, 28.5, and 20.5% of the strains were ampC, ESBL, and ampC/ESBL producers, respectively. The putative TEM gene was detected in 83% of the isolates, SHV in 20%, CTX-M in 53% and CMY ampC β-lactamase gene in 65%. Our study showed that chicken farms in Lebanon are reservoirs of ESBL and AmpC producing Gram-negative bacilli. The level of antibiotic consumption in the Lebanese veterinary medicine should be evaluated. Future studies should focus on the risk factors associated with the acquisition of multi-drug-resistant organisms in

  1. Gram-negative rod bacteremia after cardiovascular surgery: Clinical features and prognostic factors

    OpenAIRE

    田子, さやか

    2016-01-01

    博士(医学) 乙第2895号(主論文の要旨、要約、本文),著者名:Sayaka Tago・Yuji Hirai・Yusuke Ainoda・Takahiro Fujita・Ken Kikuchi,タイトル:Gram-negative rod bacteremia after cardiovascular surgery: Clinical features and prognostic factors,掲載誌:Journal of microbiology(1684-1182), immunology and infection,著作権関連情報:ℂ2015, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. All rights reserved.DOI: 10.1016/j.jmii.2015.07.008

  2. Toll-Like Receptor 4 Decoy, TOY, Attenuates Gram-Negative Bacterial Sepsis

    OpenAIRE

    Jung, Keehoon; Lee, Jung-Eun; Kim, Hak-Zoo; Kim, Ho Min; Park, Beom Seok; Hwang, Seong-Ik; Lee, Jie-Oh; Kim, Sun Chang; Koh, Gou Young

    2009-01-01

    Lipopolysaccharide (LPS), the Gram-negative bacterial outer membrane glycolipid, induces sepsis through its interaction with myeloid differentiation protein-2 (MD-2) and Toll-like receptor 4 (TLR4). To block interaction between LPS/MD-2 complex and TLR4, we designed and generated soluble fusion proteins capable of binding MD-2, dubbed TLR4 decoy receptor (TOY) using 'the Hybrid leucine-rich repeats (LRR) technique'. TOY contains the MD-2 binding ectodomain of TLR4, the LRR motif of hagfish va...

  3. One year trends in the gram-negative bacterial antibiotic susceptibility patterns in a medical intensive care unit in South India

    Directory of Open Access Journals (Sweden)

    Kaul S

    2007-01-01

    Full Text Available Purpose : To describe the changes in antibiotic susceptibility patterns of common intensive care unit pathogens with time from the medical intensive care unit of a tertiary care hospital. Methods : A prospective observational study was conducted in the medical intensive care unit (MICU of a 2100 bed tertiary care hospital in South India. All data regarding patient characteristics, disease characteristics, infective agents, identified along with their antibiotic sensitivity patterns and patient outcomes were prospectively recorded in MICU data base. Various bacterial pathogen antibiotic sensitivity patterns from August 2004 to May 2005 were prospectively documented. During this period 491 patients were admitted to the MICU. Data were analyzed using excel spreadsheets. Results : Ceftazidime resistance reduced in Klebsiella spp. while cefotaxime resistance increased. In E. coli however, ceftazidime and cefotaxime resistance increased. Klebsiella resistance to cefotaxime and ceftazidime ranged from 25-50% and 14-91%, while E. coli resistance to these antibiotics ranged from 50-70% and 50 to 80% respectively. In Pseudomonas and the non-fermenting gram-negative bacteria (NFGNB ceftazidime resistance decreased. Third generation cephalosporin resistance seemed to be reducing in the NFGNB, however, carbapenem resistance appeared to be increasing, possibly due to their increasing use. Conclusions : This study demonstrates the trend in antibiotic susceptibility pattern (AST of common gram negative infections seen in intensive care units. It demonstrates the changes seen especially after a change in the protocol antibiotic. Changes in the AST patterns of Klebsiella, E. coli, Pseudomonas and non-fermenting gram negative bacteria were seen. The data on the changing antibiotic susceptibility trends we believe is an important pillar in our efforts at infection control especially in intensive care settings.

  4. [Predictive factors for hospital infections caused by Gram-positive and Gram-negative organisms].

    Science.gov (United States)

    Domínguez-Castellano, A; Cerro, R; Bueno, C; Bringas, M J; Balonga, B; Royo, J L

    1995-12-01

    Knowing the bacterian map and clinical profile of nosocomial infections (NI) in Spain may aid the better planning of empiric antimicrobian treatment. A prospective incidence study carried out over 9 months was performed. Data collection out with the use of an EPINE project file. The chi square test and comparison of independent sample percentages were used for statistical analysis. During the study period 156 cases of NI (rate (5.5%) were detected: 65 patients with gram-negative bacilli infection (GNB), 34 by gram-positive cocci (GPC), 20 with mixed infection and 13 by Candida. The most frequent localization was urinary infection (63%) followed by surgical wound infection, pressure ulcers and respiratory infection. Of the 203 isolations, 57% corresponded to GNB, with E. coli being the most frequent microorganism. Staphylococcus aureus was the GPC most often found (95% methycilline sensitive). The profile of a patient with nosocomial infection in a hospital such as that in which the autors work would be as follows: if the patient were admitted in the department of internal medicine, was dementia or coma, denutrition, urinary catheter or neurologic disease and has NI (overall urinary infection) the infection would most likely be a caused by a gram-negative microorganism. If the patient has an i.v. line or is in a surgical ward, or has deep surgical wound infection the microorganism isolated would most likely be gram-positive.

  5. Exploring the hidden potential of fosfomycin for the fight against severe Gram-negative infections

    Directory of Open Access Journals (Sweden)

    P V Saiprasad

    2016-01-01

    Full Text Available Gram-negative resistance is a serious global crisis putting the world on the cusp of 'pre-antibiotic era'. This serious crisis has been catalysed by the rapid increase in carbapenem-resistant Enterobacteriaceae (CRE. Spurge in colistin usage to combat CRE infections leads to the reports of (colistin and carbapenem resistant enterobacteriaceae CCRE (resistance to colistin in isolates of CRE infections further jeopardising our last defence. The antibacterial apocalypse imposed by global resistance crisis requires urgent alternative therapeutic options. Interest in the use of fosfomycin renewed recently for serious systemic infections caused by multidrug-resistant Enterobacteriaceae. This review aimed at analysing the recent evidence on intravenous fosfomycin to explore its hidden potential, especially when fosfomycin disodium is going to be available in India. Although a number of promising evidence are coming up for fosfomycin, there are still areas where more work is required to establish intravenous fosfomycin as the last resort antibacterial for severe Gram-negative infections.

  6. Commensal Bacteria and Epithelial Cross Talk in the Developing Intestine

    OpenAIRE

    Rautava, Samuli; Walker, W. Allan

    2007-01-01

    Indigenous intestinal microbes have co-evolved with the intestinal immune system to form a symbiotic ecosystem. In the postnatal period, intestinal microbes provide the developing gut with stimuli that are necessary for healthy maturation of the intestinal immune system. Cross talk between the host and commensal microbes is an essential component of gut homeostasis mechanisms also in later life. During recent years, innovative research has shed light on the molecular mechanisms of these inter...

  7. In Vitro antibacterial and antibiotic-potentiation activities of four edible plants against multidrug-resistant gram-negative species

    Science.gov (United States)

    2013-01-01

    Background The present study was designed to investigate the antibacterial activities of the methanol extracts of four Cameroonian edible plants, locally used to treat microbial infections, and their synergistic effects with antibiotics against a panel of twenty nine Gram-negative bacteria including Multi-drug resistant (MDR) phenotypes expressing active efflux pumps. Methods The broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) of the extracts [alone and in the presence of the efflux pumps inhibitor (EPI) Phenylalanine-Arginine β-Naphtylamide (PAβN)], and those of antibiotics in association with the two of the most active ones, Piper nigrum and Telfairia occidentalis. The preliminary phytochemical screening of the extracts was conducted according to the standard phytochemical methods. Results Phytochemical analysis showed the presence of alkaloids and flavonoids in all studied extracts. Other chemical classes of secondary metabolites were selectively present in the extracts. The results of the MIC determination indicated that the crude extracts from P. nigrum and V. amygdalina were able to inhibit the growth of all the twenty nine studied bacteria within a concentration range of 32 to 1024 μg/mL. At a similar concentration range (32 to 1024 μg/mL) the extract from T. occidentalis inhibited the growth of 93.1% of the tested microorganisms. At MIC/2 and MIC/5, synergistic effects were noted between the extracts from P. nigrum and T. occidentalis and seven of the tested antibiotics on more than 70% of the tested bacteria. Conclusion The overall results of the present study provide information for the possible use of the studied edible plants extracts in the control of bacterial infections including MDR phenotypes. PMID:23885762

  8. Phototherapeutic spectrum expansion through synergistic effect of mesoporous silica trio-nanohybrids against antibiotic-resistant gram-negative bacterium.

    Science.gov (United States)

    Kuthati, Yaswanth; Kankala, Ranjith Kumar; Busa, Prabhakar; Lin, Shi-Xiang; Deng, Jin-Pei; Mou, Chung-Yuan; Lee, Chia-Hung

    2017-04-01

    The extensive impact of antibiotic resistance has led to the exploration of new anti-bacterial modalities. We designed copper impregnated mesoporous silica nanoparticles (Cu-MSN) with immobilizing silver nanoparticles (SNPs) to apply photodynamic inactivation (PDI) of antibiotic-resistant E. coli. SNPs were decorated over the Cu-MSN surfaces by coordination of silver ions on diamine-functionalized Cu-MSN and further reduced to silver nanoparticles with formalin. We demonstrate that silver is capable of sensitizing the gram-negative bacteria E. coli to a gram-positive specific phototherapeutic agent in vitro; thereby expanding curcumin's phototherapeutic spectrum. The mesoporous structure of Cu-MSN remains intact after the exterior decoration with silver nanoparticles and subsequent curcumin loading through an enhanced effect from copper metal-curcumin affinity interaction. The synthesis, as well as successful assembly of the functional nanomaterials, was confirmed by various physical characterization techniques. Curcumin is capable of producing high amounts of reactive oxygen species (ROS) under light irradiation, which can further improve the silver ion release kinetics for antibacterial activity. In addition, the positive charged modified surfaces of Cu-MSN facilitate antimicrobial response through electrostatic attractions towards negatively charged bacterial cell membranes. The antibacterial action of the synthesized nanocomposites can be activated through a synergistic mechanism of energy transfer of the absorbed light from SNP to curcumin. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Fermentative degradation of polyethylene glycol by a strictly anaerobic, gram-negative, nonsporeforming bacterium, Pelobacter venetianus sp. nov.

    Science.gov (United States)

    Schink, B; Stieb, M

    1983-06-01

    The synthetic polyether polyethylene glycol (PEG) with a molecular weight of 20,000 was anaerobically degraded in enrichment cultures inoculated with mud of limnic and marine origins. Three strains (Gra PEG 1, Gra PEG 2, and Ko PEG 2) of rod-shaped, gram-negative, nonsporeforming, strictly anaerobic bacteria were isolated in mineral medium with PEG as the sole source of carbon and energy. All strains degraded dimers, oligomers, and polymers of PEG up to a molecular weight of 20,000 completely by fermentation to nearly equal amounts of acetate and ethanol. The monomer ethylene glycol was not degraded. An ethylene glycol-fermenting anaerobe (strain Gra EG 12) isolated from the same enrichments was identified as Acetobacterium woodii. The PEG-fermenting strains did not excrete extracellular depolymerizing enzymes and were inhibited by ethylene glycol, probably owing to a blocking of the cellular uptake system. PEG, some PEG-containing nonionic detergents, 1,2-propanediol, 1,2-butanediol, glycerol, and acetoin were the only growth substrates utilized of a broad variety of sugars, organic acids, and alcohols. The isolates did not reduce sulfate, sulfur, thiosulfate, or nitrate and were independent of growth factors. In coculture with A. woodii or Methanospirillum hungatei, PEGs and ethanol were completely fermented to acetate (and methane). A marine isolate is described as the type strain of a new species, Pelobacter venetianus sp. nov. Its physiology and ecological significance, as well as the importance and possible mechanism of anaerobic polyether degradation, are discussed.

  10. Pentaclethra macroloba tannins fractions active against methicillin-resistant staphylococcal and Gram-negative strains showing selective toxicity

    Directory of Open Access Journals (Sweden)

    Ivana Correa Ramos Leal

    2011-12-01

    Full Text Available The ethanol extract of the vegetal species Pentaclethra macroloba (Willd. Kuntze, Fabaceae, was fractioned and the antibacterial activity was determined. The active ethyl acetate (ea fraction showed activity against Gram-positive (Staphylococcus spp. and Enterococcus spp. and Gram-negative (Pseudomonas aeruginosa, Acinetobacter spp. and Klebsiella pneumoniae multiresistant bacteria. Gallic acid derivatives were identified as the main compounds in inactive subfractions from the ea fraction, while the active one afforded ellagic acid as the major constituent when submitted to acid hydrolysis reaction, which suggests the presence of hydrolysable tannins. The minimum bactericidal concentration analysis showed a bactericide mechanism of action for the tannin subfraction found. The antibacterial mechanism of action of the active tannin subfraction against S. aureus reference strains (ATCC 29213 e 33591 was proposed adopting an in vitro assay of protein synthesis inhibition. For this, bacterial cells were labeled with [35S] methionine in the presence of the subfraction. The protein synthesis inhibition was observed at 256 µg/mL of this subfraction. At this concentration it did not present cytotoxicity in eukaryotic cells by the neutral red technique, suggesting selective toxicity. The present study is the first in vitro investigation of the antibacterial properties of tannin fractions obtained from a polar extract of P. macroloba.

  11. Pentaclethra macroloba tannins fractions active against methicillin-resistant staphylococcal and Gram-negative strains showing selective toxicity

    Directory of Open Access Journals (Sweden)

    Ivana Correa Ramos Leal

    2011-08-01

    Full Text Available The ethanol extract of the vegetal species Pentaclethra macroloba (Willd. Kuntze, Fabaceae, was fractioned and the antibacterial activity was determined. The active ethyl acetate (ea fraction showed activity against Gram-positive (Staphylococcus spp. and Enterococcus spp. and Gram-negative (Pseudomonas aeruginosa, Acinetobacter spp. and Klebsiella pneumoniae multiresistant bacteria. Gallic acid derivatives were identified as the main compounds in inactive subfractions from the ea fraction, while the active one afforded ellagic acid as the major constituent when submitted to acid hydrolysis reaction, which suggests the presence of hydrolysable tannins. The minimum bactericidal concentration analysis showed a bactericide mechanism of action for the tannin subfraction found. The antibacterial mechanism of action of the active tannin subfraction against S. aureus reference strains (ATCC 29213 e 33591 was proposed adopting an in vitro assay of protein synthesis inhibition. For this, bacterial cells were labeled with [35S] methionine in the presence of the subfraction. The protein synthesis inhibition was observed at 256 µg/mL of this subfraction. At this concentration it did not present cytotoxicity in eukaryotic cells by the neutral red technique, suggesting selective toxicity. The present study is the first in vitro investigation of the antibacterial properties of tannin fractions obtained from a polar extract of P. macroloba.

  12. Is the C-terminal insertional signal in Gram-negative bacterial outer membrane proteins species-specific or not?

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    Paramasivam Nagarajan

    2012-09-01

    Full Text Available Abstract Background In Gram-negative bacteria, the outer membrane is composed of an asymmetric lipid bilayer of phopspholipids and lipopolysaccharides, and the transmembrane proteins that reside in this membrane are almost exclusively β-barrel proteins. These proteins are inserted into the membrane by a highly conserved and essential machinery, the BAM complex. It recognizes its substrates, unfolded outer membrane proteins (OMPs, through a C-terminal motif that has been speculated to be species-specific, based on theoretical and experimental results from only two species, Escherichia coli and Neisseria meningitidis, where it was shown on the basis of individual sequences and motifs that OMPs from the one cannot easily be over expressed in the other, unless the C-terminal motif was adapted. In order to determine whether this species specificity is a general phenomenon, we undertook a large-scale bioinformatics study on all predicted OMPs from 437 fully sequenced proteobacterial strains. Results We were able to verify the incompatibility reported between Escherichia coli and Neisseria meningitidis, using clustering techniques based on the pairwise Hellinger distance between sequence spaces for the C-terminal motifs of individual organisms. We noticed that the amino acid position reported to be responsible for this incompatibility between Escherichia coli and Neisseria meningitidis does not play a major role for determining species specificity of OMP recognition by the BAM complex. Instead, we found that the signal is more diffuse, and that for most organism pairs, the difference between the signals is hard to detect. Notable exceptions are the Neisseriales, and Helicobacter spp. For both of these organism groups, we describe the specific sequence requirements that are at the basis of the observed difference. Conclusions Based on the finding that the differences between the recognition motifs of almost all organisms are small, we assume that

  13. Appropriateness of gram-negative agent use at a tertiary care hospital in the setting of significant antimicrobial resistance.

    Science.gov (United States)

    Vora, Neil M; Kubin, Christine J; Furuya, E Yoko

    2015-01-01

    Background.  Practicing antimicrobial stewardship in the setting of widespread antimicrobial resistance among gram-negative bacilli, particularly in urban areas, is challenging. Methods.  We conducted a retrospective cross-sectional study at a tertiary care hospital with an established antimicrobial stewardship program in New York, New York to determine appropriateness of use of gram-negative antimicrobials and to identify factors associated with suboptimal antimicrobial use. Adult inpatients who received gram-negative agents on 2 dates, 1 June 2010 or 1 December 2010, were identified through pharmacy records. Clinical data were collected for each patient. Use of gram-negative agents was deemed optimal or suboptimal through chart review and according to hospital guidelines. Data were compared using χ(2) or Fischer's exact test for categorical variables and Student t test or Mann-Whitney U test for continuous variables. Results.  A total of 356 patients were included who received 422 gram-negative agents. Administration was deemed suboptimal in 26% of instances, with the most common reason being spectrum of activity too broad. In multivariable analysis, being in an intensive care unit (adjusted odds ratio [aOR], .49; 95% confidence interval [CI], .29-.84), having an infectious diseases consultation within the previous 7 days (aOR, .52; 95% CI, .28-.98), and having a history of multidrug-resistant gram-negative bacilli within the past year (aOR, .24; 95% CI, .09-.65) were associated with optimal gram-negative agent use. Beta-lactam/beta-lactamase inhibitor combination drug use (aOR, 2.6; 95% CI, 1.35-5.16) was associated with suboptimal use. Conclusions.  Gram-negative agents were used too broadly despite numerous antimicrobial stewardship program activities.

  14. Bacterial antigens alone can influence intestinal barrier integrity, but live bacteria are required for initiation of intestinal inflammation and injury.

    Science.gov (United States)

    Sydora, Beate C; Martin, Sarah M; Lupicki, Maryla; Dieleman, Levinus A; Doyle, Jason; Walker, John W; Fedorak, Richard N

    2006-06-01

    Intestinal flora plays a critical role in the initiation and perpetuation of inflammatory bowel disease. This study examined whether live fecal bacteria were necessary for the initiation of this inflammatory response or whether sterile fecal material would provoke a similar response. Three preparations of fecal material were prepared: (1) a slurry of live fecal bacteria, (2) a sterile lysate of bacterial antigens, and (3) a sterile filtrate of fecal water. Each preparation was introduced via gastric gavage into the intestines of axenic interleukin-10 gene-deficient mice genetically predisposed to develop inflammatory bowel disease. Intestinal barrier integrity and degrees of mucosal and systemic inflammations were determined for each preparation group. Intestinal barrier integrity, as determined by mannitol transmural flux, was altered by both live fecal bacterial and sterile lysates of bacterial antigens, although it was not altered by sterile filtrates of fecal water. However, only live fecal bacteria initiated mucosal inflammation and injury and a systemic immune response. Fecal bacterial antigens in the presence of live bacteria and sterile fecal bacterial antigens have different effects on the initiation and perpetuation of intestinal inflammation.

  15. Molecular epidemiology of carbapenem resistant gram-negative bacilli from infected pediatric population in tertiary - care hospitals in Medellín, Colombia: an increasing problem.

    Science.gov (United States)

    Vanegas, Johanna M; Parra, O Lorena; Jiménez, J Natalia

    2016-09-01

    Gram-negative bacilli are a cause of serious infections in the pediatric population. Carbapenem are the treatment of choice for infections caused by multidrug-resistant Gram-negative bacilli, but the emergence of carbapenem resistance has substantially reduced access to effective antimicrobial regimens. Children are a population vulnerable to bacterial infections and the emergence of resistance can worsen prognosis. The aim of this study is to describe the clinical and molecular characteristics of infections caused by carbapenem-resistant Gram-negative bacilli in pediatric patients from five tertiary-care hospitals in Medellín, Colombia. A cross-sectional study was conducted in five tertiary-care hospitals from June 2012 to June 2014. All pediatric patients infected by carbapenem-resistant Gram-negative bacilli were included. Clinical information for each patient was obtained from medical records. Molecular analyses included PCR for detection of bla VIM, bla IMP bla NDM, bla OXA-48 and bla KPC genes and PFGE and MLST for molecular typing. A total of 59 patients were enrolled, most of them less than 1 year old (40.7 % n = 24), with a previous history of antibiotic use (94.9 %; n = 56) and healthcare-associated infections - predominately urinary tract infections (31.0 %; n = 18). Klebsiella pneumoniae was the most frequent bacteria (47.4 %), followed by Enterobacter cloacae (40.7 %) and Pseudomonas aeruginosa (11.9 %). For K. pneumoniae, KPC was the predominant resistance mechanism (85.7 %; n = 24) and ST14 was the most common clone (39.3 % n = 11), which included strains closely related by PFGE. In contrast, E. cloacae and P. aeruginosa were prevailing non-carbapenemase-producing isolates (only KPC and VIM were detected in 1 and 3 isolates, respectively) and high genetic diversity according to PFGE and MLST was found in the majority of the cases. In recent years, increasing carbapenem-resistant bacilli in children has become in a matter

  16. Zonulin Regulates Intestinal Permeability and Facilitates Enteric Bacteria Permeation in Coronary Artery Disease

    OpenAIRE

    Li, Chuanwei; Gao, Min; Zhang, Wen; Chen, Caiyu; Zhou, Faying; Hu, Zhangxu; Zeng, Chunyu

    2016-01-01

    Several studies have reported an association between enteric bacteria and atherosclerosis. Bacterial 16S ribosomal RNA (rRNA) gene belong to Enterobacteriaceae have been detected in atherosclerotic plaques. How intestinal bacteria go into blood is not known. Zonulin reversibly modulate intestinal permeability (IP), the circulating zonulin levels were increased in diabetes, obesity, all of which are risk factors for atherosclerosis. It is unclear whether the circulating zonulin levels were cha...

  17. Comparative Activity of Several Antimicrobial Agents against Nosocomial Gram-Negative Rods Isolated across Canada

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    Shelley R Scriver

    1995-01-01

    Full Text Available In 1992, a surveillance study was performed in Canada to determine the susceptibility of nosocomial Gram-negative rods to several wide spectrum antimicrobials. Consecutive isolates from 10 institutions, as well as additional strains of selected species of Enterobacteriaceae that are known to possess the Bush group 1 beta-lactamase, were tested for susceptibility to 12 antimicrobials. Third-generation cephalosporin resistance was found to be as high as 29% in Enterobacter cloacae that possesses the Bush group 1 beta-lactamase and less than 4% in those isolates not possessing this enzyme. Cefepime equalled or exceeded the activity of the third-generation cephalosporins against the species of Enterobacteriaceae that demonstrated resistance to the third-generation cephalosporins.

  18. Stenotrophomonas maltophilia: A Gram-Negative Bacterium Useful for Transformations of Flavanone and Chalcone

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    Edyta Kostrzewa-Susłow

    2017-10-01

    Full Text Available A group of flavones, isoflavones, flavanones, and chalcones was subjected to small-scale biotransformation studies with the Gram-negative Stenotrophomonas maltophilia KB2 strain in order to evaluate the capability of this strain to transform flavonoid compounds and to investigate the relationship between compound structure and transformation type. The tested strain transformed flavanones and chalcones. The main type of transformation of compounds with a flavanone moiety was central heterocyclic C ring cleavage, leading to chalcone and dihydrochalcone structures, whereas chalcones underwent reduction to dihydrochalcones and cyclisation to a benzo-γ-pyrone moiety. Substrates with a C-2–C-3 double bond (flavones and isoflavones were not transformed by Stenotrophomonas maltophilia KB2.

  19. High Prevalence of Antimicrobial-resistant Gram-negative Colonization in Hospitalized Cambodian Infants.

    Science.gov (United States)

    Turner, Paul; Pol, Sreymom; Soeng, Sona; Sar, Poda; Neou, Leakhena; Chea, Phal; Day, Nicholas Pj; Cooper, Ben S; Turner, Claudia

    2016-08-01

    Antimicrobial-resistant Gram-negative infections are a significant cause of mortality in young infants. We aimed to determine characteristics of, and risk factors for, colonization and invasive infection caused by 3rd generation cephalosporin (3GC) or carbapenem-resistant organisms in outborn infants admitted to a neonatal unit (NU) in Cambodia. During the first year of operation, patients admitted to the Angkor Hospital for Children NU, Siem Reap, Cambodia, underwent rectal swabbing on admission and twice weekly until discharge. Swabs were taken also from 7 environmental sites. Swabs were cultured to identify 3GC or carbapenem-resistant Acinetobacter sp., Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. The study included 333 infants with a median age at NU admission of 10 days (range, 0-43). Colonization by ≥1 3GC-resistant organism was detected in 85.9% (286/333). Admission swabs were collected in 289 infants: 61.9% were colonized by a 3GC-resistant organism at the time of admission, and a further 23.2% were colonized during hospitalization, at a median of 4 days [95% confidence interval: 3-5]. Probiotic treatment (hazard ratio: 0.58; 95% confidence interval: 0.35-0.98) was associated with delayed colonization. Colonization by a carbapenem-resistant organism occurred in 25 (7.5%) infants. Six infants had NU-associated K. pneumoniae bacteremia; phenotypically identical colonizing strains were found in 3 infants. Environmental colonization occurred early. Colonization by antimicrobial-resistant Gram-negative organisms occurred early in hospitalized Cambodian infants and was associated with subsequent invasive infection. Trials of potential interventions such as probiotics are needed.

  20. Rectal carriage of extended-spectrum beta-lactamase-producing gram-negative bacilli in community settings in Madagascar.

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    Perlinot Herindrainy

    Full Text Available BACKGROUND: Extended-spectrum ß-lactamase-producing Enterobacteria (ESBL-PE emerged at the end of the 1980s, causing nosocomial outbreaks and/or hyperendemic situations in hospitals and long-term care facilities. In recent years, community-acquired infections due to ESBL-PE have spread worldwide, especially across developing countries including Madagascar. OBJECTIVES: This study aimed to determine the prevalence and risk factors of intestinal carriage of ESBL-PE in the community of Antananarivo. METHODS: Non-hospitalized patients were recruited in three health centers in different socio economic settings. Fresh stool collected were immediately plated on Drigalski agar containing 3 mg/liter of ceftriaxone. Gram-negative bacilli species were identified and ESBL production was tested by a double disk diffusion (cefotaxime and ceftazidime +/- clavulanate assay. Characterization of ESBLs were perfomed by PCR and direct sequencing. Molecular epidemiology was analysed by Rep-PCR and ERIC-PCR. RESULTS: 484 patients were screened (sex ratio  =  1.03, median age 28 years. 53 ESBL-PE were isolated from 49 patients (carrier rate 10.1%. The isolates included Escherichia coli (31, Klebsiella pneumoniae (14, Enterobacter cloacae (3, Citrobacter freundii (3, Kluyvera spp. (1 and Pantoae sp. (1. In multivariate analysis, only the socioeconomic status of the head of household was independently associated with ESBL-PE carriage, poverty being the predominant risk factor. CONCLUSIONS: The prevalence of carriage of ESBL in the community of Antananarivo is one of the highest reported worldwide. This alarming spread of resistance genes should be stopped urgently by improving hygiene and streamlining the distribution and consumption of antibiotics.

  1. [Interaction between humans and intestinal bacteria as a determinant for intestinal health : intestinal microbiome and inflammatory bowel diseases].

    Science.gov (United States)

    Haller, Dirk; Hörmannsperger, G

    2015-02-01

    Recent scientific results underline the importance of the intestinal microbiome, the totality of all intestinal microbes and their genes, for the health of the host organism. The intestinal microbiome can therefore be considered as a kind of "external organ". It has been shown that the intestinal microbiota is a complex and dynamic ecosystem that influences host immunity and metabolism beyond the intestine. The composition and functionality of the intestinal microbiota is of major importance for the development and maintenance of intestinal functions. Inflammatory bowel diseases (IBD) are characterized by dysregulated interactions between the host and its microbiota.The present contribution summarizes current knowledge of the composition and development of the intestinal microbiome and gives an overview of the bidirectional interaction between host and microbiota. The contribution informs about insights regarding the role of the intestinal microbiota in IBD and finally discusses the protective potential of microbial therapies in the context of IBD.

  2. Lactic Acid Bacteria and the Human Intestinal Microbiome

    NARCIS (Netherlands)

    Douillard, F.P.; Vos, de W.M.

    2015-01-01

    The great interest in the human microbiome has revived attention paid to LAB presence in the human intestine. This chapter first discusses the LAB associated with the human intestinal microbiota and their potential roles in health and diseases. It then addresses recent metagenomic studies that

  3. Woody forages effect the intestinal bacteria diversity of golden pompano Trachinotus ovatus.

    Science.gov (United States)

    Chen, Biao; Gao, Liu-Ling; Pan, Qing

    2018-02-27

    To understand the effect of woody forages on golden pompano (Trachinotus ovatus) intestinal bacteria diversity and exploit new aquafeed ingredients, the diets of Moringa oleifera Lam (MOL), Broussonetia papyrifera (BP), Neolamarckia cadamba (NC) and Folium mori (FM) formulated with 70% of reference (Ref) diet and 30% of the four woody plants leaves were fed to golden pompano with initial body weight of 34.4 ± 0.5 g for 56 days, respectively. Bacteria diversity of golden pompano intestine and tank water (W) samples were analyzed using high-throughput illumina sequencing and the result indicated that the dominate phyla of golden pompano intestine were Proteobacteria, Bacteroidetes, Firmicutes and Fusobacteria. Proteobacteria in BP was significantly higher than those in NC (P forages and Ref diet presented higher similarity and the bacteria community of golden pompano intestine were clearly distinguished from those of W. Phylogenetic investigation of communities by reconstruction of unobserved states showed that the intestinal bacteria dominant metabolism pathways of golden pompano fed with woody forages and Ref diet were biosynthesis of amino acids and carbon metabolism. Overall, the present study first successfully characterized the intestinal bacteria diversity of golden pompano.

  4. Antibacterial and antibiotic-resistance modifying activity of the extracts and compounds from Nauclea pobeguinii against Gram-negative multi-drug resistant phenotypes.

    Science.gov (United States)

    Seukep, Jackson A; Sandjo, Louis P; Ngadjui, Bonaventure T; Kuete, Victor

    2016-07-07

    Multi-drug resistance of Gram-negative bacteria constitutes a major obstacle in the antibacterial fight worldwide. The discovery of new and effective antimicrobials and/or resistance modulators is necessary to combat the spread of resistance or to reverse the multi-drug resistance. In this study, we investigated the antibacterial and antibiotic-resistance modifying activities against 29 Gram-negative bacteria including multi-drug resistant (MDR) phenotypes of the methanol extracts from Nauclea pobeguiinii leaves (NPL), Nauclea pobeguiinii bark (NPB) and six compounds from the bark extract, identified as 3-acetoxy-11-oxo-urs-12-ene (1), p-coumaric acid (2), citric acid trimethyl ester (3), resveratrol (4), resveratrol β- D -glucopyranoside (5) and strictosamide (6). The broth microdilution method was used to determine the minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of crude extracts and compounds as well as the antibiotic-resistance modifying effects of MPB and 4. MIC determinations indicate values ranging from 32-1024 μg/mL for NPB and NPL on 89.7 % and 69.0 % of the tested bacterial strains respectively. MIC values below 100 μg/mL were obtained with NPB against Escherichia coli ATCC10536, AG100 and Enterobacter aerogenes CM64 strains. The lowest MIC value for crude extracts of 32 μg/mL was obtained with NPB against E. coli ATCC10536. Compound 4 was active all tested bacteria, whilst 1, 3 and 6 displayed weak and selective inhibitory effects. The corresponding MIC value (16 μg/mL) was obtained with 4 against Klebsiella pneumoniae KP55 strain. Synergistic effects of the combination of NPB with chloramphenicol (CHL), kanamycin (KAN) as well as that of compound 4 with streptomycin (STR) and ciprofloxacin (CIP) were observed. The present study provides information on the possible use of Nauclea pobeguinii and compound 4 in the control of Gram-negative bacterial infections including MDR phenotypes. It also indicates

  5. Insights into the extremotolerance of Acinetobacter radioresistens 50v1, a gram-negative bacterium isolated from the Mars Odyssey spacecraft.

    Science.gov (United States)

    McCoy, K B; Derecho, I; Wong, T; Tran, H M; Huynh, T D; La Duc, M T; Venkateswaran, K; Mogul, R

    2012-09-01

    The microbiology of the spacecraft assembly process is of paramount importance to planetary exploration, as the biological contamination that can result from remote-enabled spacecraft carries the potential to impact both life-detection experiments and extraterrestrial evolution. Accordingly, insights into the mechanisms and range of extremotolerance of Acinetobacter radioresistens 50v1, a Gram-negative bacterium isolated from the surface of the preflight Mars Odyssey orbiter, were gained by using a combination of microbiological, enzymatic, and proteomic methods. In summary, A. radioresistens 50v1 displayed a remarkable range of survival against hydrogen peroxide and the sequential exposures of desiccation, vapor and plasma phase hydrogen peroxide, and ultraviolet irradiation. The survival is among the highest reported for non-spore-forming and Gram-negative bacteria and is based upon contributions from the enzyme-based degradation of H(2)O(2) (catalase and alkyl hydroperoxide reductase), energy management (ATP synthase and alcohol dehydrogenase), and modulation of the membrane composition. Together, the biochemical and survival features of A. radioresistens 50v1 support a potential persistence on Mars (given an unintended or planned surface landing of the Mars Odyssey orbiter), which in turn may compromise the scientific integrity of future life-detection missions.

  6. Species-Level Discrimination of Psychrotrophic Pathogenic and Spoilage Gram-Negative Raw Milk Isolates Using a Combined MALDI-TOF MS Proteomics-Bioinformatics-based Approach.

    Science.gov (United States)

    Vithanage, Nuwan R; Bhongir, Jeevana; Jadhav, Snehal R; Ranadheera, Chaminda S; Palombo, Enzo A; Yeager, Thomas R; Datta, Nivedita

    2017-06-02

    Identification of psychrotrophic pathogenic and spoilage Gram-negative bacteria using rapid and reliable techniques is important in commercial milk processing, as these bacteria can produce heat-resistant proteases and act as postprocessing contaminants in pasteurized milk. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is a proven technology for identification of bacteria in food, however, may require optimization for identification of pathogenic and spoilage bacteria in milk and dairy products. The current study evaluated the effects of various culture conditions and sample preparation methods on assigning of raw milk isolates to the species level by MALDI-TOF MS. The results indicated that culture media, incubation conditions (temperature and time), and sample preparation significantly affected the identification rates of bacteria to the species level. Nevertheless, the development of spectral libraries of isolates grown on different media using a web tool for hierarchical clustering of peptide mass spectra (SPECLUST) followed by a ribosomal protein based bioinformatics approach significantly enhanced the assigning of bacteria, with at least one unique candidate biomarker peak identified for each species. Phyloproteomic relationships based on spectral profiles were compared to phylogenetic analysis using 16S rRNA gene sequences and demonstrated similar clustering patterns with significant discriminatory power. Thus, with appropriate optimization, MALDI-TOF MS is a valuable tool for species-level discrimination of pathogenic and milk spoilage bacteria.

  7. Treatment and Outcome of Carbapenem-Resistant Gram-Negative Bacilli Blood-Stream Infections in a Tertiary Care Hospital.

    Science.gov (United States)

    Shah, Pooja G; Shah, Sweta R

    2015-07-01

    Infections caused by carbapenem-resistant bacteria constitute a major challenge for current medical practice. To describe treatment and outcome of carbapenem-resistant Gram-negative bacilli (GNB) blood-stream infection (BSI) caused by these organisms at a tertiary care hospital in Mumbai. Carbapenem-resistant isolates from blood cultures were collected from January 2013 to April 2013. Identification and antimicrobial susceptibility testing were performed using Vitek 2 analyzer (Biomerieux Ltd.). Carbapenemase production was detected by modified Hodge's test (MHT). Patient's medical history, treatment and co-morbid conditions were noted. Outcomes of BSIs were evaluated. Forty-two isolates of carbapenem-resistant GNB isolated from BSIs were Enterobacteriaceae spp. (19), Acinetobacter baumannii (15), and Pseudomonas aeruginosa (8). Colistin had maximum in vitro activity with 97% against Enterobacteriaceae, 100% against Acinetobacter, and 100% activity against Pseudomonas aeruginosa isolates. Positivity of MHT was 92.9%. Outcome of colistin mono and combination therapy was comparable with 83% and 79%, respectively. Outcome of colistin and carbapenem combination therapy was found to be 100 percent. High incidences of bacteremia by carbapenem-resistant GNB including Enterobacteriaceae is a worrisome trend. Treatment options are compromised and only available option is colistin which has its own limitation. Colistin monotherapy may be non-inferior compared to combination therapy for treating BSIs caused by isolates with minimum inhibitory concentration (MIC) for colistin as ≤0.5 mg/l. Combined use of the colistin and carbapenem may provide good therapeutic options for BSI caused by carbapenem-resistant GNB and warrants further investigations.

  8. Rz/Rz1 lysis gene equivalents in phages of Gram-negative hosts.

    Science.gov (United States)

    Summer, Elizabeth J; Berry, Joel; Tran, Tram Anh T; Niu, Lili; Struck, Douglas K; Young, Ry

    2007-11-09

    Under usual laboratory conditions, lysis by bacteriophage lambda requires only the holin and endolysin genes, but not the Rz and Rz1 genes, of the lysis cassette. Defects in Rz or Rz1 block lysis only in the presence of high concentrations of divalent cations. The lambda Rz and Rz1 lysis genes are remarkable in that Rz1, encoding an outer membrane lipoprotein, is completely embedded in the +1 register within Rz, which itself encodes an integral inner membrane protein. While Rz and Rz1 equivalents have been identified in T7 and P2, most phages, including such well-studied classic phages as T4, P1, T1, Mu and SP6, lack annotated Rz/Rz1 equivalents. Here we report that a search strategy based primarily on gene arrangement and membrane localization signals rather than sequence similarity has revealed that Rz/Rz1 equivalents are nearly ubiquitous among phages of Gram-negative hosts, with 120 of 137 phages possessing genes that fit the search criteria. In the case of T4, a deletion of a non-overlapping gene pair pseT.2 and pseT.3 identified as Rz/Rz1 equivalents resulted in the same divalent cation-dependent lysis phenotype. Remarkably, in T1 and six other phages, Rz/Rz1 pairs were not found but a single gene encoding an outer membrane lipoprotein with a C-terminal transmembrane domain capable of integration into the inner membrane was identified. These proteins were named "spanins," since their protein products are predicted to span the periplasm providing a physical connection between the inner and outer membranes. The T1 spanin gene was shown to complement the lambda Rz-Rz1- lysis defect, indicating that spanins function as Rz/Rz1 equivalents. The widespread presence of Rz/Rz1 or their spanin equivalents in phages of Gram-negative hosts suggests a strong selective advantage and that their role in the ecology of these phages is greater than that inferred from the mild laboratory phenotype.

  9. Carbapenem-Resistant Non-Glucose-Fermenting Gram-Negative Bacilli: the Missing Piece to the Puzzle

    Science.gov (United States)

    Gniadek, Thomas J.; Carroll, Karen C.

    2016-01-01

    The non-glucose-fermenting Gram-negative bacilli Pseudomonas aeruginosa and Acinetobacter baumannii are increasingly acquiring carbapenem resistance. Given their intrinsic antibiotic resistance, this can cause extremely difficult-to-treat infections. Additionally, resistance gene transfer can occur between Gram-negative species, regardless of their ability to ferment glucose. Thus, the acquisition of carbapenemase genes by these organisms increases the risk of carbapenemase spread in general. Ultimately, infection control practitioners and clinical microbiologists need to work together to determine the risk carried by carbapenem-resistant non-glucose-fermenting Gram-negative bacilli (CR-NF) in their institution and what methods should be considered for surveillance and detection of CR-NF. PMID:26912753

  10. Risk factors for carbapenem resistant bacteraemia and mortality due to gram negative bacteraemia in a developing country

    International Nuclear Information System (INIS)

    Kalam, K.; Kumar, S.; Ali, S.; Baqi, S.; Qamar, F.

    2014-01-01

    Objective: To identify the risk factors for carbapenem resistant bacteraemia and mortality due to gram negative bacteraemia in a developing country. Methods: A prospective cohort study was conducted at the Sindh Institute of Urology and Transplantation (SIUT) from June to October 2012. Hospitalized patients > 15 years of age with gram negative bacteraemia were included and followed for a period of 2 weeks for in hospital mortality. Data was collected and analyzed for 243 subjects. Multivariate analysis was used to determine the risk factors for carbapenem resistant bacteraemia and mortality due to gram negative bacteraemia. Crude and adjusted odds ratio and 95% CI are reported. Results: A total of 729 out of 1535 (47.5%) cultures were positive for gram negative isolates. Out of 243 subjects, 117 (48%) had an MDR isolate. Having an MDR isolate on culture (AOR, 2.33; 95% CI, 1.35 -4.0), having multiple positive cultures (AOR, 1.8; 95% CI, 0.94 -3.4) and stay in ICU >48 hours (AOR, 2.0 ; 95% CI, 1.12 -3.78) were identified as significant risk factors for mortality due to gram negative organisms. Risk factors for carbapenem resistant bacteraemia were age >50 years (AOR, 1.83; 95% CI, 1.0-3.5), septic shock on presentation (AOR 2.53; 95% CI, 1.03 -6.2) , ICU stay of >72 hours (AOR 2.40; 95% CI, 1.14-5.0) and receiving immunosuppressant medications (AOR 2.23; 95% CI, 0.74 - 6.7). Conclusion: There is a high burden of MDR and carbapenem resistant gram negative bacteraemia, with a high mortality rate. (author)

  11. Altered glucose kinetics in diabetic rats during Gram-negative infection

    International Nuclear Information System (INIS)

    Lang, C.H.; Dobrescu, C.; Bagby, G.J.; Spitzer, J.J.

    1987-01-01

    The present study examined the purported exacerbating effect of sepsis on glucose metabolism in diabetes. Diabetes was induced in rats by an intravenous injection of 70 or 45 mg/kg streptozotocin. The higher dose produced severe diabetes, whereas the lower dose of streptozotocin produced a miler, latent diabetes. After a chronic diabetic state had developed for 4 wk, rats had catheters implanted and sepsis induced by intraperitoneal injections of live Escherichia coli. After 24 h of sepsis the blood glucose concentration was unchanged in nondiabetics and latent diabetics, but glucose decreased from 15 to 8 mM in the septic severe diabetic group. This decrease in blood glucose was not accompanied by alterations in the plasma insulin concentration. Glucose turnover, assessed by the constant intravenous infusion of [6- 3 H]- and [U- 14 C]glucose, was elevated in the severe diabetic group, compared with either latent diabetics or nondiabetics. Sepsis increased the rate of glucose disappearance in nondiabetic rats but had no effect in either group of diabetic animals. Sepsis also failed to alter the insulinogenic index, used to estimate the insulin secretory capacity, in diabetic rats. Thus the present study suggests that the imposition of nonlethal Gram-negative sepsis on severe diabetic animals does not further impair glucose homeostasis and that the milder latent diabetes was not converted to a more severe diabetic state by the septic challenge

  12. Evaluation of pyrrolidonyl arylamidase for the identification of nonfermenting Gram-negative rods.

    Science.gov (United States)

    Bombicino, Karina A; Almuzara, Marisa N; Famiglietti, Angela M R; Vay, Carlos

    2007-01-01

    To evaluate the activity of pyrrolidonyl arylamidase (PYR) for the differentiation and identification of nonfermenting gram negative rods (NFGNR), 293 isolates were tested. A 24 h culture of each test organism was prepared. From this a 108-109 cfu/mL suspension was added to 0.25 mL of sterile physiologic solution. A PYR disk was then added and the test was incubated for 30 minutes at 35-37 degrees C, at environmental atmosphere. Reading was done by adding 1 drop of cinnamaldehyde reagent. Strains of Acinetobacter baumannii, Acinetobacter haemolyticus, Alcaligenes faecalis, Bergeyella zoohelcum, Bordetella bronchiseptica, Bordetella hinzii, Brevundimonas diminuta, Brevundimonas vesicularis, Brucella ovis, Brucella spp., Brucella suis, Burkholderia cepacia complex, Moraxella catarrhalis, Moraxella lacunata, Moraxella nonliquefaciens, Moraxella osloensis, Oligella ureolytica, Pseudomonas alcaligenes, Pseudomonas mendocina, Pseudomonas pseudoalcaligenes, Pseudomonas putida, Pseudomonas stutzeri, Pseudomonas Vb3, Psychrobacter phenylpyruvicus, and Stenotrophomonas maltophilia were PYR negative. On the other hand Achromobacter piechaudii, Achromobacter denitrificans, Achromobacter xylosoxidans, Burkholderia gladioli, Chryseobacterium gleum-indologenes, Comamonas testosroni, Cupriavidus pauculus, Delftia acidovorans, Elizabethkingia meningoseptica, Myroides spp., Ochrobactrum anthropi, Pseudomonas oryzihabitans, Ralstonia pickettii, Rhizobium radiobacter, Shewanella spp., Sphingobacterium multivorum, Sphingobacterium spiritivorum, and Weeksella virosa were PYR positive. Finally, Acinetobacter lwoffii, Pseudomonas aeruginosa, Pseudomonas fluorescens, Roseomonas spp., and Sphingomonas paucimobilis-parapaucimobilis were PYR variable. PYR testing should be considered as a useful tool to facilitate the identification of NFGNR.

  13. In vitro susceptibility pattern of extended spectrum ?-lactamase producing gram negative bacilli against tetracyclines

    International Nuclear Information System (INIS)

    Gill, M.M.

    2015-01-01

    Extended Spectrum beta-lactamases (ESBLs) are emerging as common nosocomial pathogens and important cause of mortality and morbidity, if not treated properly. The need of the hour is to find effective treatment options for dealing with ESBL producing organisms. This study was aimed to evaluate in vitro susceptibility pattern of extended spectrum beta-lactamase producers against tetracyclines. Methods: This descriptive cross-sectional study was carried out in the department of Microbiology, Army Medical College, Rawalpindi, National University of Sciences and Technology over a period of 6 months. Seventy eight non-duplicate isolates were included in the study. ESBL detection was done using Jarlier et al method. In vitro susceptibility of tetracyclines like tetracycline, doxycycline, minocycline and tigecycline was then tested using Modified Kirby Bauer disc diffusion method. The zones of inhibition were measured after completion of incubation period and interpreted as per CLSI and FDA guidelines. Results: Approximately 56.4% of the isolates were Escherichia coli, 28.2% were Klebsiella pneumoniae, 10.26% were Enterobacter species, and 2.6% were each Klebsiella oxytoca and Acinetobacter species. ESBLs were found to be most sensitive to tigecycline, intermediate in susceptibility to minocycline while least sensitive to doxycycline and tetracycline. Conclusion: Among tetracyclines, tigecycline has best in vitro susceptibility against ESBL producing Gram negative rods. (author)

  14. [News of antibiotic resistance among Gram-negative bacilli in Algeria].

    Science.gov (United States)

    Baba Ahmed-Kazi Tani, Z; Arlet, G

    2014-06-01

    Antibiotic resistance has become a major public health problem in Algeria. Indeed the past decade, we have seen a significant increase in resistance to antibiotics especially in Gram-negative bacilli. Resistance to β-lactams in enterobacteria is dominated by the production of ESBL CTX-M-3 and CTX-M-15. The strains producing these enzymes are often the cause of potentially serious infections in both hospital and community settings. Identified plasmid cephalosporinases are CMY-2, CMY-12 and DHA-1. The isolation of strains of Enterobacteriaceae and Pseudomonas aeruginosa producing carbapenemases