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Sample records for gram-negative bacterial infection

  1. Gram-Negative Bacterial Wound Infections

    Science.gov (United States)

    2016-07-01

    32). In the case of the latter infective agents, miltefosine proved to be an effective antibacterial agent against P. aeruginosa; its administration ...neutropenic via intraperitoneal administration of 150 mg/kg and 100 mg/kg cyclophosphamide in sterile saline on day 4 and day 1 prior to infection (day...319 putative nicotinate -nucleotide diphosphorylase is located downstream of plc1 and transcribed in 320 the opposite direction. The plc1 gene

  2. [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

  3. 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.

  4. Infection-related hemolysis and susceptibility to Gram-negative bacterial co-infection

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    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.

  5. 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.

  6. 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.

  7. Curative Treatment of Severe Gram-Negative Bacterial Infections by a New Class of Antibiotics Targeting LpxC

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    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. 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.

  9. 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

  10. 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.

  11. Pleural effusion adenosine deaminase: a candidate biomarker to discriminate between Gram-negative and Gram-positive bacterial infections of the pleural space

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    Ruolin Li

    2016-05-01

    Full Text Available OBJECTIVES: Delay in the treatment of pleural infection may contribute to its high mortality. In this retrospective study, we aimed to evaluate the diagnostic accuracy of pleural adenosine deaminase in discrimination between Gram-negative and Gram-positive bacterial infections of the pleural space prior to selecting antibiotics. METHODS: A total of 76 patients were enrolled and grouped into subgroups according to Gram staining: 1 patients with Gram-negative bacterial infections, aged 53.2±18.6 years old, of whom 44.7% had empyemas and 2 patients with Gram-positive bacterial infections, aged 53.5±21.5 years old, of whom 63.1% had empyemas. The pleural effusion was sampled by thoracocentesis and then sent for adenosine deaminase testing, biochemical testing and microbiological culture. The Mann-Whitney U test was used to examine the differences in adenosine deaminase levels between the groups. Correlations between adenosine deaminase and specified variables were also quantified using Spearman’s correlation coefficient. Moreover, receiver operator characteristic analysis was performed to evaluate the diagnostic accuracy of pleural effusion adenosine deaminase. RESULTS: Mean pleural adenosine deaminase levels differed significantly between Gram-negative and Gram-positive bacterial infections of the pleural space (191.8±32.1 U/L vs 81.0±16.9 U/L, p<0.01. The area under the receiver operator characteristic curve was 0.689 (95% confidence interval: 0.570, 0.792, p<0.01 at the cutoff value of 86 U/L. Additionally, pleural adenosine deaminase had a sensitivity of 63.2% (46.0-78.2%; a specificity of 73.7% (56.9-86.6%; positive and negative likelihood ratios of 2.18 and 0.50, respectively; and positive and negative predictive values of 70.6% and 66.7%, respectively. CONCLUSIONS: Pleural effusion adenosine deaminase is a helpful alternative biomarker for early and quick discrimination of Gram-negative from Gram-positive bacterial infections of the

  12. 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, ...

  13. Myeloid cell sirtuin-1 expression does not alter host immune responses to Gram-negative endotoxemia or Gram-positive bacterial infection.

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    Laura E Crotty Alexander

    Full Text Available The role of sirtuin-1 (SIRT1 in innate immunity, and in particular the influence of SIRT1 on antimicrobial defense against infection, has yet to be reported but is important to define since SIRT1 inhibitors are being investigated as therapeutic agents in the treatment of cancer, Huntington's disease, and autoimmune diseases. Given the therapeutic potential of SIRT1 suppression, we sought to characterize the role of SIRT1 in host defense. Utilizing both pharmacologic methods and a genetic knockout, we demonstrate that SIRT1 expression has little influence on macrophage and neutrophil antimicrobial functions. Myeloid SIRT1 expression does not change mortality in gram-negative toxin-induced shock or gram-positive bacteremia, suggesting that therapeutic suppression of SIRT1 may be done safely without suppression of myeloid cell-specific immune responses to severe bacterial infections.

  14. 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.

  15. Globally dispersed mobile drug-resistance genes in gram-negative bacterial isolates from patients with bloodstream infections in a US urban general hospital.

    Science.gov (United States)

    Adams-Sapper, S; Sergeevna-Selezneva, J; Tartof, S; Raphael, E; Diep, B An; Perdreau-Remington, F; Riley, L W

    2012-07-01

    Mobile drug-resistance genes with identical nucleic acid sequences carried by multidrug-resistant Escherichia coli strains that cause community-acquired infections are becomingly increasingly dispersed worldwide. Over a 2-year period, we analysed gram-negative bacterial (GNB) pathogens from the blood of inpatients at an urban public hospital to determine what proportion of these isolates carried such globally dispersed drug-resistance genes. Of 376 GNB isolates, 167 (44 %) were Escherichia coli, 50 (13 %) were Klebsiella pneumoniae, 25 (7 %) were Pseudomonas aeruginosa, 25 (7 %) were Proteus mirabilis and 20 (5 %) were Enterobacter cloacae; the remainder (24 %) comprised 26 different GNB species. Among E. coli isolates, class 1 integrons were detected in 64 (38 %). The most common integron gene cassette configuration was dfrA17-aadA5, found in 30 (25 %) of 119 drug-resistant E. coli isolates and in one isolate of Moraxella morganii. Extended-spectrum β-lactamase (ESBL) genes were found in 16 E. coli isolates (10 %). These genes with identical sequences were found in nearly 40 % of bloodstream E. coli isolates in the study hospital, as well as in a variety of bacterial species from clinical and non-clinical sources worldwide. Thus, a substantial proportion of bloodstream infections among hospitalized patients were caused by E. coli strains carrying drug-resistance genes that are dispersed globally in a wide variety of bacterial species.

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

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    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

  17. 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...

  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. Inhaled antibiotics for gram-negative respiratory infections.

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    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.

  20. 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

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

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    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.

  2. Surface display of proteins by Gram-negative bacterial autotransporters

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    Mourez Michael

    2006-06-01

    Full Text Available Abstract Expressing proteins of interest as fusions to proteins of the bacterial envelope is a powerful technique with many biotechnological and medical applications. Autotransporters have recently emerged as a good tool for bacterial surface display. These proteins are composed of an N-terminal signal peptide, followed by a passenger domain and a translocator domain that mediates the outer membrane translocation of the passenger. The natural passenger domain of autotransporters can be replaced by heterologous proteins that become displayed at the bacterial surface by the translocator domain. The simplicity and versatility of this system has made it very attractive and it has been used to display functional enzymes, vaccine antigens as well as polypeptides libraries. The recent advances in the study of the translocation mechanism of autotransporters have raised several controversial issues with implications for their use as display systems. These issues include the requirement for the displayed polypeptides to remain in a translocation-competent state in the periplasm, the requirement for specific signal sequences and "autochaperone" domains, and the influence of the genetic background of the expression host strain. It is therefore important to better understand the mechanism of translocation of autotransporters in order to employ them to their full potential. This review will focus on the recent advances in the study of the translocation mechanism of autotransporters and describe practical considerations regarding their use for bacterial surface display.

  3. 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.

  4. Gram-Negative Bacterial Wound Infections

    Science.gov (United States)

    2014-05-01

    Associated with Bovine Brucellosis in Pakistan S. Ali1, H. Neubauer2 , F. Melzer2, I. Khan’, Q. Ali’, E. N. Abatih’, N. Ullah1, M. W. Akbar’, S...Pasteurellosis in Bovine Animals in the Lori Province, Armenia A. Abrahamyan; State Food Safety Services, Armenia 503 African Swine Fever Detection... Bovine Tuberculosis in Cattle Farms in Zaria and Kaduna and Possible Transmission Through Milk P. N. Mbianga, V. J. Umoh, A. I. 0, K. C. A; Ahmadu

  5. Development of Quorum-Based Anti-Virulence Therapeutics Targeting Gram-Negative Bacterial Pathogens

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    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.

  6. Monotherapy versus Combination Therapy against Nonbacteremic Carbapenem-resistant Gram-negative Infections: A Retrospective Observational Study

    OpenAIRE

    Ghafur, Abdul; Devarajan, Vidyalakshmi; Raja, T.; Easow, Jose; Raja, M. A.; Sreenivas, Sankar; Ramakrishnan, Balasubramaniam; Raman, S. G.; Devaprasad, Dedeepiya; Venkatachalam, Balaji; Nimmagadda, Ramesh

    2017-01-01

    Background: Superiority of colistin–carbapenem combination therapy (CCCT) over colistin monotherapy (CMT) against carbapenem-resistant Gram-negative bacterial (CRGNB) infections is not conclusively proven. Aim: The aim of the current study was to analyze the effectiveness of both strategies against CRGNB nonbacteremic infections. Design: This was a retrospective observational cohort study. Subjects and Methods: Case record analysis of patients who had CRGNB nonbacteremic infections identified...

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

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    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.

  8. 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.

  9. Sinus surgery postpones chronic Gram-negative lung infection

    DEFF Research Database (Denmark)

    Alanin, M C; Aanaes, K; Høiby, N

    2016-01-01

    of pulmonary samples positive for GNB. We investigated whether the effect is sustained. METHODOLOGY: We report the effect of ESS and adjuvant therapy three years postoperatively in a CF cohort participating in this prospective clinical follow-up study. The primary endpoint was the lung infection status defined...

  10. 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.

  11. 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

  12. 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 .

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. Prevalence of Gram-negative Pathogens and their antimicrobial susceptibility in bacterial meningitis in pediatric cases

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    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.

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

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    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. 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.

  20. Gram-Negative Infections in Adult Intensive Care Units of Latin America and the Caribbean

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    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.

  1. 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.

  2. In Vivo Biofilm Formation, Gram-Negative Infections and TAS2R38 Polymorphisms in CRSw NP Patients.

    Science.gov (United States)

    Cantone, Elena; Negri, Rossella; Roscetto, Emanuela; Grassia, Rossella; Catania, Maria Rosaria; Capasso, Pasquale; Maffei, Marianna; Soriano, Amata Amy; Leone, Carlo Antonio; Iengo, Maurizio; Greco, Luigi

    2018-03-23

    Among the predisposing factors implicated in the immune response to airway bacterial infections, genetic variations of the bitter taste receptor TAS2R38, which is expressed in the cilia of the human sinonasal epithelial cells, seem to be associated with susceptibility to chronic rhinosinusitis (CRS) and in vitro biofilm formation. Polymorphisms in TAS2R38 generate two common haplotypes: the nonfunctional AVI (Alanine, Valine, Isoleucine) and the functional PAV (Proline, Alanine, Valine) alleles, with the latter protecting against gram-negative sinonasal infections. The aim of this study is to investigate for the first time the relevance of TAS2R38 genetic variants in the susceptibility to bacterial infections associated with in vivo biofilm formation in chronic rhinosinusitis with nasal polyps (CRSwNP) patients. A prospective study on 100 adult patients undergoing functional endoscopic sinus surgery (FESS) for CRSwNP. Propylthiouracile (PROP) testing and TAS2R38 genotyping were applied to characterize patients for receptor functionality. Sinonasal mucosa samples were processed for microbiological examination and biofilm detection. The nonfunctional genotype is more frequent among CRS patients than in the general population (25% vs. 18.4%, P = 0.034). Airway gram-negative infections are primarily associated with the AVI haplotype (88.9% vs. 11.1% PAV/PAV-functional genotype, P = 0.023). Biofilm formation is prevalent in CRS patients with the AVI nontaster phenotype (62.5% vs. 33.3% PAV taster or supertaster phenotype, P = 0.05). Our findings confirm an inverse correlation between TAS2R38 functionality and gram-negative infections in Italian patients with CRSwNP. In addition, for the first time we demonstrated a relationship between in vivo microbial biofilm and TAS2R38 receptor variants. 2b. Laryngoscope, 2018. © 2018 The American Laryngological, Rhinological and Otological Society, Inc.

  3. [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.

  4. 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.

  5. 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.

  6. 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.

  7. Predicting subcellular localization of gram-negative bacterial proteins by linear dimensionality reduction method.

    Science.gov (United States)

    Wang, Tong; Yang, Jie

    2010-01-01

    With the rapid increase of protein sequences in the post-genomic age, the need for an automated and accurate tool to predict protein subcellular localization becomes increasingly important. Many efforts have been tried. Most of them aim to find the optimal classification scheme and less of them take the simplifying the complexity of biological system into consideration. This work shows how to decrease the complexity of biological system with linear DR (Dimensionality Reduction) method by transforming the original high-dimensional feature vectors into the low-dimensional feature vectors. A powerful sequence encoding scheme by fusing PSSM (Position-Specific Score Matrix) and Chou's PseAA (Pseudo Amino Acid) composition is proposed to represent the protein samples. Then, the K-NN (K-Nearest Neighbor) classifier is employed to identify the subcellular localization based on their reduced low-dimensional feature vectors. Experimental results thus obtained are quite encouraging, indicating that the aforementioned linear DR method is quite promising in dealing with complicated biological problems, such as predicting the subcellular localization of Gram-negative bacterial proteins.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Using the nonlinear dimensionality reduction method for the prediction of subcellular localization of Gram-negative bacterial proteins.

    Science.gov (United States)

    Wang, Tong; Yang, Jie

    2009-11-01

    One of the central problems in computational biology is protein function identification in an automated fashion. A key step to achieve this is predicting to which subcellular location the protein belongs, since protein localization correlates closely with its function. A wide variety of methods for protein subcellular localization prediction have been proposed over recent years. Linear dimensionality reduction (DR) methods have been introduced to address the high-dimensionality problem by transforming the representation of protein sequences. However, this approach is not suitable for some complex biological systems that have nonlinear characteristics. Herein, we use nonlinear DR methods such as the kernel DR method to capture the nonlinear characteristics of a high-dimensional space. Then, the K-nearest-neighbor (K-NN) classifier is employed to identify the subcellular localization of Gram-negative bacterial proteins based on their reduced low-dimensional features. Experimental results thus obtained are quite encouraging, indicating that the applied nonlinear DR method is effective to deal with this complicated problem of predicting subcellular localization of Gram-negative bacterial proteins. An online web server for predicting subcellular location of Gram-negative bacterial proteins is available at (http://202.120.37.185:8080/).

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

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    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.

  15. 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.

  16. 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

  17. Structural and enzymatic characterization of ABgp46, a novel phage endolysin with broad anti-Gram-negative bacterial activity

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    Hugo eOliveira

    2016-02-01

    Full Text Available The present study demonstrates the antibacterial potential of a phage endolysin against Gram-negative pathogens, particularly on A. baumannii multidrug resistant strains. We have cloned, heterologously expressed and characterized a novel endolysin (ABgp46 from Acinetobacter phage vb_AbaP_CEB1 and tested its antibacterial activity against several multidrug-resistant A. baumannii strains. LC-MS revealed ABgp46 is an N-acetylmuramidase, that is also active at a broad pH range (4.0-10.0 and up to 50°C. Interestingly, ABgp46 has intrinsic and specific anti-A. baumannii activity, reducing up to 2 logs of multidrug resistant strains, in a 2 hour-time frame. By combining ABgp46 with several organic acids that act as outer membrane permeabilizing agents, it is possible to increase and broaden its antibacterial activity to other Gram-negative bacterial pathogens. Especially in the presence of citric and malic acid, ABgp46 reduces A. baumannii below detection limit (> 5 log and more than 4 logs P. aeruginosa and Salmonella Typhimurium strains. Overall, this globular endolysin presents a broad and high activity against Gram-negative pathogens, that can be enhanced in presence of citric and malic acid, and be used in human and veterinary medicine.

  18. Structural and Enzymatic Characterization of ABgp46, a Novel Phage Endolysin with Broad Anti-Gram-Negative Bacterial Activity.

    Science.gov (United States)

    Oliveira, Hugo; Vilas Boas, Diana; Mesnage, Stéphane; Kluskens, Leon D; Lavigne, Rob; Sillankorva, Sanna; Secundo, Francesco; Azeredo, Joana

    2016-01-01

    The present study demonstrates the antibacterial potential of a phage endolysin against Gram-negative pathogens, particularly against multidrug resistant strains of Acinetobacter baumannii. We have cloned, heterologously expressed and characterized a novel endolysin (ABgp46) from Acinetobacter phage vb_AbaP_CEB1 and tested its antibacterial activity against several multidrug-resistant A. baumannii strains. LC-MS revealed that ABgp46 is an N-acetylmuramidase, that is also active over a broad pH range (4.0-10.0) and temperatures up to 50°C. Interestingly, ABgp46 has intrinsic and specific anti-A. baumannii activity, reducing multidrug resistant strains by up to 2 logs within 2 h. By combining ABgp46 with several organic acids that act as outer membrane permeabilizing agents, it is possible to increase and broaden antibacterial activity to include other Gram-negative bacterial pathogens. In the presence of citric and malic acid, ABgp46 reduces A. baumannii below the detection limit (>5 log) and more than 4 logs Pseudomonas aeruginosa and Salmonella typhimurium strains. Overall, this globular endolysin exhibits a broad and high activity against Gram-negative pathogens, that can be enhanced in presence of citric and malic acid, and be used in human and veterinary medicine.

  19. 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.

  20. Infective endocarditis due to multidrug resistant gram-negative bacilli: single centre experience over 5 years.

    Science.gov (United States)

    Durante-Mangoni, Emanuele; Andini, Roberto; Agrusta, Federica; Iossa, Domenico; Mattucci, Irene; Bernardo, Mariano; Utili, Riccardo

    2014-09-01

    Infective endocarditis (IE) due to gram-negative (GN) bacilli is uncommon. Although multi- and extensively-drug resistant (MDR/XDR) GN infections are emerging, very few data are available on IE due to these microrganisms. In this study, we describe the clinical characteristics, course and outcome of five contemporary, definite, MDR/XDR GNIE cases seen at our centre. All patients had been admitted to a hospital during the 6months before IE onset, 2 were on hemodialysis and 3 on intravenous medications. Three of the 5 cases were hospital-acquired. Intracardiac prosthetic devices were present in all cases (3 central venous lines, 2 prosthetic heart valves, 2 pacemakers). Mean Charlson comorbidity index was 5.8. Causative pathogens were XDR Pseudomonas aeruginosa (2 cases), XDR Acinetobacter baumannii, MDR Burkolderia cepacia and MDR Escherichia coli (1 case each). Concomitant pathogens with a MDR/XDR phenotype were isolated in 4 patients. Both valves and intracardiac devices and left and right sides of the heart were involved. The rate of complications was high. Antibiotic treatment hinged on the use of colistin, a carbapenem or both. Cardiovascular surgical procedures were performed in 3 patients. Despite aggressive therapeutic regimens, outcomes were poor. Clearance of bacteremia was obtained in 3 patients, in-hospital death occurred in 3 patients, only 1 patient survived during follow up. MDR/XDR GN are emerging as a cause of IE in carriers of intracardiac prostheses with extensive healthcare contacts and multiple comorbidities. Resistant GNIE has a complicated course and shows a dismal prognosis. Copyright © 2014 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  1. [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.

  2. Intravenous Colistin Use for Multidrug-Resistant Gram-Negative Infections in Pediatric Patients

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    Ayşe Karaaslan

    2016-12-01

    Full Text Available Background: The emergence of infections due to multidrug-resistant Gram-negative bacilli (MDR-GNB has led to the resurrection of colistin use. The data on colistin use and drug-related adverse effects in children are scarce. Aims: In this study, we aimed to evaluate the clinical efficacy and safety of colistin use in critically ill pediatric patients. Study Design: This study has a retrospective study design. Methods: Sixty-one critically ill children were identified through the department’s patient files archive during the period from January 2011 to November 2014. Results: Twenty-nine females and thirty-two males with a mean±standard deviation (SD age of 61±9 months (range 0-216, median 12 months received IV colistin due to MDR-GNB infections. Bacteremia (n=23, 37.7% was the leading diagnosis, followed by pneumonia (n=19, 31%, clinical sepsis (n=7, 11.4%, wound infection (n=6, 9.8%, urinary tract infection (n=5, 8.1% and meningitis (n=1, 1.6%. All of the isolates were resistant to carbapenems; however, all were susceptible to colistin. The isolated microorganisms in decreasing order of frequency were: Acinetobacter baumanni (n=27, 44.2%, Pseudomonas aeruginosa (n=17, 27.8%, Klebsiella pneumoniae (n=6, 9.8%, K. pneumoniae and Stenotrophomonas maltophilia (n=1, 1.6%, K. pneumoniae and A. baumanni (n=1, 1.6%, K. oxytoca (n=1, 1.6% and Enterobacter cloacae (n=1, 1.6%. In seven patients, no microorganisms were detected; however, five of these patients were colonized by carbapenem-resistant K. pneumoniae. The mean duration of colistin therapy was 12 days (range 3-45. Colistin was administered concomitantly with one of the following antibiotics: carbapenem (n=50, %82, ampicillin-sulbactam (n=5, 8%, quinolones (n=5, 8%, rifampicin (n=1, 1.6%. Carbapenem was the most frequently used antibiotic. Nephrotoxicity was observed in only 1 patient, and we did not observe neurotoxicity in this study. All the patients received intravenous colistin

  3. Monotherapy versus Combination Therapy against Nonbacteremic Carbapenem-resistant Gram-negative Infections: A Retrospective Observational Study.

    Science.gov (United States)

    Ghafur, Abdul; Devarajan, Vidyalakshmi; Raja, T; Easow, Jose; Raja, M A; Sreenivas, Sankar; Ramakrishnan, Balasubramaniam; Raman, S G; Devaprasad, Dedeepiya; Venkatachalam, Balaji; Nimmagadda, Ramesh

    2017-12-01

    Superiority of colistin-carbapenem combination therapy (CCCT) over colistin monotherapy (CMT) against carbapenem-resistant Gram-negative bacterial (CRGNB) infections is not conclusively proven. The aim of the current study was to analyze the effectiveness of both strategies against CRGNB nonbacteremic infections. This was a retrospective observational cohort study. Case record analysis of patients who had CRGNB nonbacteremic infections identified over a period of 4 years (January 2012-December 2015) was done by medical record review at a tertiary care center in India. P Multivariate analysis was performed using Cox regression. Out of 153 patients (pneumonia 115, urinary tract infection 17, complicated skin and soft-tissue infection 18, intra-abdominal infection 1, and meningitis 2), 92 patients received CCCT and 61 received CMT. Univariate analysis revealed higher Acute Physiology and Chronic Health Evaluation II (APACHE II) score, pneumonia as the diagnosis, and Klebsiella as the causative organism to be the risk factors for higher 28-day mortality ( P = 0.036, 0.006, 0.016, respectively). Combination therapy had no significant impact on mortality (odds ratio [OR] = 0.91, 95% confidence interval [CI] = 0.327-2.535, P = 0.857). Multivariate analysis revealed that higher APACHE II score and infection due to Klebsiella were found to be independent risk factors for higher mortality (OR = 3.16 and 4.9, 95% CI = 1.34-7.4 and 2.19-11.2, P = 0.008 and 0.0001, respectively). In our retrospective single-center series of CRGNB nonbacteremic infections, CCCT was not superior to CMT. Multicenter large observational studies or prospective randomized clinical trials are the need of the hour.

  4. Gram-Negative Bacterial Lipopolysaccharide Stimulates Activin A Secretion from Human Amniotic Epithelial Cells

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    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.

  5. 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.

  6. 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

  7. One year trends in the gram-negative bacterial antibiotic susceptibility patterns in a medical intensive care unit in South India

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    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.

  8. 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.

  9. 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.

  10. Innate immunity against Granulibacter bethesdensis, an emerging gram-negative bacterial pathogen.

    Science.gov (United States)

    Zarember, Kol A; Marshall-Batty, Kimberly R; Cruz, Anna R; Chu, Jessica; Fenster, Michael E; Shoffner, Adam R; Rogge, Larissa S; Whitney, Adeline R; Czapiga, Meggan; Song, Helen H; Shaw, Pamela A; Nagashima, Kunio; Malech, Harry L; DeLeo, Frank R; Holland, Steven M; Gallin, John I; Greenberg, David E

    2012-03-01

    Acetic acid bacteria were previously considered nonpathogenic in humans. However, over the past decade, five genera of Acetobacteraceae have been isolated from patients with inborn or iatrogenic immunodeficiencies. Here, we describe the first studies of the interactions of the human innate immune system with a member of this bacterial family, Granulibacter bethesdensis, an emerging pathogen in patients with chronic granulomatous disease (CGD). Efficient phagocytosis of G. bethesdensis by normal and CGD polymorphonuclear leukocytes (CGD PMN) required heat-labile serum components (e.g., C3), and binding of C3 and C9 to G. bethesdensis was detected by immunoblotting. However, this organism survived in human serum concentrations of ≥90%, indicating a high degree of serum resistance. Consistent with the clinical host tropism of G. bethesdensis, CGD PMN were unable to kill this organism, while normal PMN, in the presence of serum, reduced the number of CFU by about 50% after a 24-h coculture. This finding, together with the observations that G. bethesdensis was sensitive to H(2)O(2) but resistant to LL-37, a human cationic antimicrobial peptide, suggests an inherent resistance to O(2)-independent killing. Interestingly, 10 to 100 times greater numbers of G. bethesdensis were required to achieve the same level of reactive oxygen species (ROS) production induced by Escherichia coli in normal PMN. In addition to the relative inability of the organism to elicit production of PMN ROS, G. bethesdensis inhibited both constitutive and FAS-induced PMN apoptosis. These properties of reduced PMN activation and resistance to nonoxidative killing mechanisms likely play an important role in G. bethesdensis pathogenesis.

  11. 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

  12. 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

  13. Incidence of carbapenem resistant nonfermenting gram negative bacilli from patients with respiratory infections in the intensive care units

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    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.

  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. 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

    heterologous overexpression of almost all OMPs should be feasible in E. coli and other Gram-negative bacterial model organisms. This is relevant especially for biotechnology applications, where recombinant OMPs are used e.g. for the development of vaccines. For the species in which the motif is significantly different, we identify the residues mainly responsible for this difference that can now be changed in heterologous expression experiments to yield functional proteins.

  16. 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

  17. 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.

  18. HdhCTL1 is a novel C-type lectin of abalone Haliotis discus hannai that agglutinates Gram-negative bacterial pathogens.

    Science.gov (United States)

    Zhang, Jian; Qiu, Reng; Hu, Yong-hua

    2014-12-01

    C-type lectins (CTLs) are Ca(2+)-dependent carbohydrate recognition proteins, which play important roles in the innate immunity of both vertebrates and invertebrates. In this study, we identified and characterized a C-type lectin (named HdhCTL1) from Pacific abalone, Haliotis discus hannai. HdhCTL1 is composed of 176 amino acid residues and shares low (23.9%) identity with the known CTL of abalone. HdhCTL1 possesses a putative signal peptide and a carbohydrate-recognition domain (CRD) typical of CTLs. The CRD of HdhCTL1 contains four disulfide bond-forming cysteine residues that are highly conserved in CTLs. HdhCTL1 mRNA was detected in a wide range of tissues and expressed abundantly in the digestive gland. Experimental infection with the bacterial pathogen Vibrio anguillarum significantly upregulated HdhCTL1 expression in a time-dependent manner. Recombinant HdhCTL1 (rHdhCTL1) purified from Escherichia coli was able to agglutinate Gram-negative bacterial pathogens. The agglutinating ability of rHdhCTL1 was abolished in the presence of mannose. These results suggest that HdhCTL1 is a novel CTL which is likely to be involved in host defense against bacterial infection. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. 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.

  20. A prediction tool for nosocomial multi-drug Resistant Gram-Negative Bacilli infections in critically ill patients - prospective observational study.

    Science.gov (United States)

    Vasudevan, Anupama; Mukhopadhyay, Amartya; Li, Jialiang; Yuen, Eugene Goh Yu; Tambyah, Paul Ananth

    2014-11-25

    The widespread use of empiric broad spectrum antibiotics has contributed to the global increase of Resistant Gram-Negative Bacilli (RGNB) infections in intensive care units (ICU). The aim of this study was to develop a tool to predict nosocomial RGNB infections among ICU patients for targeted therapy. We conducted a prospective observational study from August'07 to December'11. All adult patients who were admitted and stayed for more than 24 hours at the medical and surgical ICU's were included. All patients who developed nosocomial RGNB infections 48 hours after ICU admission were identified. A prediction score was formulated by using independent risk factors obtained from logistic regression analysis. This was prospectively validated with a subsequent cohort of patients admitted to the ICUs during the following time period of January-September 2012. Seventy-six patients with nosocomial RGNB Infection (31bacteremia) were compared with 1398 patients with Systemic Inflammatory Response Syndrome (SIRS) without any gram negative bacterial infection/colonization admitted to the ICUs during the study period. The following independent risk factors were obtained by a multivariable logistic regression analysis - prior isolation of Gram negative organism (coeff: 1.1, 95% CI 0.5-1.7); Surgery during current admission (coeff: 0.69, 95% CI 0.2-1.2); prior Dialysis with end stage renal disease (coeff: 0.7, 95% CI 0.1-1.1); prior use of Carbapenems (coeff: 1.3, 95% CI 0.3-2.3) and Stay in the ICU for more than 5 days (coeff: 2.4, 95% CI 1.6-3.2). It was validated prospectively in a subsequent cohort (n = 408) and the area-under-the-curve (AUC) of the GSDCS score for predicting nosocomial ICU acquired RGNB infection and bacteremia was 0.77 (95% CI 0.68-0.89 and 0.78 (95% CI 0.69-0.89) respectively. The GSDCS (0-4.3) score clearly differentiated the low (0-1.3), medium (1.4-2.3) and high (2.4-4.3) risk patients, both for RGNB infection (p:0.003) and bacteremia (p:0

  1. Nonfermenting gram-negative bacilli infections in a tertiary care hospital in Kolar, Karnataka

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    A Malini

    2009-01-01

    Conclusion : P. aeruginosa and A. baumannii were the common NFGNB isolated in our study from patients of, urinary tract infection, bacteremia, surgical site infections, and ventilator associated pneumonia. P. aeruginosa showed good sensitivity to imipenem, amikacin, and cefoperazone while A. baumannii showed good sensitivity to imipenem and piperacillin.

  2. 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.

  3. 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.

  4. Nonfermenting Gram-negative Bacilli other than Pseudomonas aeruginosa and Acinetobacter Spp. Causing Respiratory Tract Infections in a Tertiary Care Center

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    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.

  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. Antibiotic Resistance and Regulation of the Gram-Negative Bacterial Outer Membrane Barrier by Host Innate Immune Molecules

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    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.

  7. Purification and characterization of tenecin 4, a new anti-Gram-negative bacterial peptide, from the beetle Tenebrio molitor.

    Science.gov (United States)

    Chae, Jun-Ho; Kurokawa, Kenji; So, Young-In; Hwang, Hyun Ok; Kim, Min-Su; Park, Ji-Won; Jo, Yong-Hun; Lee, Yong Seok; Lee, Bok Luel

    2012-03-01

    The biochemical characterization of novel antimicrobial peptides (AMPs) and the determination of ligand molecules that induce AMP production are essential for understanding the host innate immune response in insects. Here, we purified a new 14-kDa AMP, named tenecin 4, from the larval hemolymph of the beetle Tenebrio molitor. Tenecin 4 contains 14% glycine residues and has moderate similarities both to the C-terminal region of Drosophila attacin and to silk-moth gloverin proteins. Purified tenecin 4 showed bactericidal activity against Gram-negative Escherichia coli but not against Gram-positive Bacillus subtilis or the fungus Candida albicans. Tenecin 4 production was induced by Toll cascade-activating ligands, such as β-1,3-glucan, lysine-type peptidoglycan and active Spätzle, and by the probable Imd pathway-activating ligand monomeric meso-diaminopimelic acid-type peptidoglycan. Taken together, these data show that tenecin 4 is a defense protein against Gram-negative pathogens and is induced by multiple ligands in Tenebrio larvae. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

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    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.

  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. Genome analysis of Cronobacter phage vB_CsaP_Ss1 reveals an endolysin with potential for biocontrol of Gram-negative bacterial pathogens.

    Science.gov (United States)

    Endersen, Lorraine; Guinane, Caitriona M; Johnston, Christopher; Neve, Horst; Coffey, Aidan; Ross, R Paul; McAuliffe, Olivia; O'Mahony, Jim

    2015-02-01

    Bacteriophages and their derivatives are continuously gaining impetus as viable alternative therapeutic agents to control harmful multidrug-resistant bacterial pathogens, particularly in the food industry. The reduced efficacy of conventional antibiotics has resulted in a quest to find novel alternatives in the war against infectious disease. This study describes the full-genome sequence of Cronobacter phage vB_CsaP_Ss1, with subsequent cloning and expression of its endolysin, capable of hydrolysing Gram-negative peptidoglycan. Cronobacter phage vB_CsaP_Ss1 is composed of 42 205 bp of dsDNA with a G+C content of 46.1 mol%. A total of 57 ORFs were identified of which 18 could be assigned a putative function based on similarity to characterized proteins. The genome of Cronobacter phage vB_CsaP_Ss1 showed little similarity to any other bacteriophage genomes available in the database and thus was considered unique. In addition, functional analysis of the predicted endolysin (LysSs1) was also investigated. Zymographic experiments demonstrated the hydrolytic activity of LysSs1 against Gram-negative peptidoglycan, and this endolysin thus represents a novel candidate with potential for use against Gram-negative pathogens. © 2015 The Authors.

  11. Beta-lactams in continuous infusion for Gram-negative bacilli osteoarticular infections: an easy method for clinical use.

    Science.gov (United States)

    Ribera, Alba; Soldevila, Laura; Rigo-Bonnin, Raul; Tubau, Fe; Padullés, Ariadna; Gómez-Junyent, Joan; Ariza, Javier; Murillo, Oscar

    2018-01-23

    Continuous infusion (CI) of beta-lactams could optimize their pharmacokinetic/pharmacodynamic indices, especially in difficult-to-treat infections. To validate an easy-to-use method to guide beta-lactams dosage in CI (formula). A retrospective analysis was conducted of a prospectively collected cohort (n = 24 patients) with osteoarticular infections caused by Gram-negative bacilli (GNB) managed with beta-lactams in CI. Beta-lactams dose was calculated using a described formula (daily dose = 24 h × beta-lactam clearance × target "steady-state" concentration) to achieve concentrations above the MIC. We correlated the predicted concentration (C pred  = daily dose/24 h × beta-lactam clearance) with the patient's observed concentration (C obs ) measured by UPLC-MS/MS (Spearman's coefficient). The most frequent microorganism treated was P. aeruginosa (21 cases; 9 MDR). Beta-lactams in CI were ceftazidime (n = 14), aztreonam (7), and piperacillin/tazobactam (3), mainly used in combination (12 with colistin, 5 with ciprofloxacin) and administered without notable side effects. The plasma C obs was higher overall than C pred ; the Spearman correlation between both concentrations was rho = 0.6 (IC 95%: 0.2-0.8) for all beta-lactams, and rho = 0.8 (IC 95%: 0.4-1) for those treated with ceftazidime. The formula may be useful in clinical practice for planning the initial dosage of beta-lactams in CI, while we await a systematic therapeutic drug monitoring. The use of beta-lactams in CI was safe.

  12. 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.

  13. Detection of endotoxin in the plasma of patients with gram-negative bacterial sepsis by the Limulus amoebocyte lysate assay.

    Science.gov (United States)

    Pearson, F C; Dubczak, J; Weary, M; Bruszer, G; Donohue, G

    1985-01-01

    A total of 120 Limulus amoebocyte lysate (LAL) determinations were made on plasma obtained from normal, healthy human blood donors. Results demonstrated a mean endotoxin level in blood of 0.02 to 1.57 pg/ml. The amount of Escherichia coli endotoxin added to human plasma samples can be quantitated by both nephelometry and turbidimetry. Endotoxin-spiked samples were shown to be significantly different from unspiked samples. When plasma samples were collected from 45 patients hospitalized at three centers, a strong association was demonstrated between a positive Limulus amoebocyte lysate assay and a septic condition. Sensitivity, specificity, and false-positive and false-negative rates for the Limulus amoebocyte lysate assay as a diagnostic test for gram-negative bacteremia were estimated. PMID:4008617

  14. Resistance among Gram-negative ESKAPE pathogens isolated from hospitalized patients with intra-abdominal and urinary tract infections in Latin American countries: SMART 2013–2015

    Directory of Open Access Journals (Sweden)

    James A. Karlowsky

    2017-05-01

    Full Text Available Gram-negative ESKAPE pathogens (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species are important etiologic agents of nosocomial infection that are frequently resistant to broad-spectrum antimicrobial agents. Gram-negative ESKAPE pathogens were collected from hospitalized patients in 11 Latin American countries from 2013 to 2015 as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART global surveillance program. In total, 2113 isolates from intra-abdominal infections (IAI and 970 isolates from urinary tract infections (UTI were tested against antimicrobial agents using standardized CLSI broth microdilution methodology. Of the agents tested, amikacin demonstrated the highest rates of susceptibility (% for K. pneumoniae (92.2, 92.3, Enterobacter spp. (97.5, 92.1, and P. aeruginosa (85.3, 75.2 isolates from both IAI and UTI, respectively. Ertapenem (68.5, 62.6 and imipenem (79.2, 75.9 showed substantially higher rates of susceptibility (% than other β-lactams, including piperacillin-tazobactam (35.9, 37.4 against ESBL-positive isolates of K. pneumoniae from IAI and UTI, respectively. Rates of susceptibility to all agents tested against A. baumannii were ≤30.9%. Gram-negative ESKAPE pathogens isolated from Latin America demonstrated compromised in vitro susceptibility to commonly prescribed broad-spectrum, parenteral antimicrobial agents. Continued surveillance is warranted. New antimicrobial agents with potent activity against Gram-negative ESKAPE pathogens are urgently needed.

  15. 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.

  16. Is colistin effective in the treatment of infections caused by multidrug-resistant (MDR) or extremely drug-resistant (XDR) gram-negative microorganisms in children?

    Science.gov (United States)

    Ozsurekci, Yasemin; Aykac, Kubra; Cengiz, Ali Bulent; Bayhan, Cihangul; Sancak, Banu; Karadag Oncel, Eda; Kara, Ates; Ceyhan, Mehmet

    2016-06-01

    The increasing incidence of infections caused by multidrug-resistant (MDR) or extremely drug-resistant (XDR) gram-negative organisms has led to the reemergence of colistin use. Clinical and demographic data were collected on 94 pediatric patients diagnosed with MDR or XDR gram-negative infections and treated with either a colistin-containing regimen (colistin group) or at least one antimicrobial agent other than colistin (noncolistin group). The overall clinical response rates were 65.8% in the colistin group and 70.0% in the noncolistin group (P = 0.33). The infection-related mortality rates were 11% in the colistin group and 13.3% in the noncolistin group (P = 0.74). There was no statistically significant difference in nephrotoxicity in the colistin and noncolistin groups. Colistin therapy was at least as effective and as safe as beta-lactam antibiotics or quinolones, with or without aminoglycosides, in the treatment of infections caused by gram-negative organisms and may be a therapeutic option in children. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. 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...

  18. CD44 Deficiency Is Associated with Increased Bacterial Clearance but Enhanced Lung Inflammation During Gram-Negative Pneumonia

    NARCIS (Netherlands)

    van der Windt, Gerritje J. W.; Florquin, Sandrine; de Vos, Alex F.; van't Veer, Cornelis; Queiroz, Karla C. S.; Liang, Jiurong; Jiang, Dianhua; Noble, Paul W.; van der Poll, Tom

    2010-01-01

    Klebsiella pneumoniae is a frequently isolated causative pathogen in respiratory tract infections. CD44 is a transmembrane adhesion molecule that has been implicated in several immunological processes. To determine the role of CD44 during Klebsiella pneumonia, we intranasally infected wild-type and

  19. Effects of Photodynamic Therapy on Gram-Positive and Gram-Negative Bacterial Biofilms by Bioluminescence Imaging and Scanning Electron Microscopic Analysis

    Science.gov (United States)

    Núñez, Silvia C.; Azambuja, Nilton; Fregnani, Eduardo R.; Rodriguez, Helena M.H.; Hamblin, Michael R.; Suzuki, Hideo; Ribeiro, Martha S.

    2013-01-01

    Abstract Objective: The aim of this study was to test photodynamic therapy (PDT) as an alternative approach to biofilm disruption on dental hard tissue, We evaluated the effect of methylene blue and a 660 nm diode laser on the viability and architecture of Gram-positive and Gram-negative bacterial biofilms. Materials and methods: Ten human teeth were inoculated with bioluminescent Pseudomonas aeruginosa or Enterococcus faecalis to form 3 day biofilms in prepared root canals. Bioluminescence imaging was used to serially quantify and evaluate the bacterial viability, and scanning electron microscopic (SEM) imaging was used to assess architecture and morphology of bacterial biofilm before and after PDT employing methylene blue and 40 mW, 660 nm diode laser light delivered into the root canal via a 300 μm fiber for 240 sec, resulting in a total energy of 9.6 J. The data were statistically analyzed with analysis of variance (ANOVA) followed by Tukey test. Results: The bacterial reduction showed a dose dependence; as the light energy increased, the bioluminescence decreased in both planktonic suspension and in biofilms. The SEM analysis showed a significant reduction of biofilm on the surface. PDT promoted disruption of the biofilm and the number of adherent bacteria was reduced. Conclusions: The photodynamic effect seems to disrupt the biofilm by acting both on bacterial cells and on the extracellular matrix. PMID:23822168

  20. 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.

  1. 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.

  2. Evaluation of the Limulus amoebocyte lysate test in conjunction with a gram negative bacterial plate count for detecting irradiation of chicken

    International Nuclear Information System (INIS)

    Scotter, S.L.; Wood, R.; McWeeny, D.J.

    1990-01-01

    A study to evaluate the potential of the Limulus amoebocyte lysate (LAL) test in conjunction with a Gram negative bacterial (GNB) plate count for detecting the irradiation of chicken is described. Preliminary studies demonstrated that chickens irradiated at an absorbed dose of 2.5 kGy could be differentiated from unirradiated birds by measuring levels of endotoxin and of numbers of GNB on chicken skin. Irradiated birds were found to have endotoxin levels similar to those found in unirradiated birds but significantly lower numbers of GNB. In a limited study the test was found to be applicable to birds from different processors. The effect of temperature abuse on the microbiological profile, and thus the efficacy of the test, was also investigated. After temperature abuse, the irradiated birds were identifiable at worst up to 3 days after irradiation treatment at the 2.5 kGy level and at best some 13 days after irradiation. Temperature abuse at 15 0 C resulted in rapid recovery of surviving micro-organisms which made differentiation of irradiated and unirradiated birds using this test unreliable. The microbiological quality of the bird prior to irradiation treatment also affected the test as large numbers of GNB present on the bird prior to irradiation treatment resulted in larger numbers of survivors. In addition, monitoring the developing flora after irradiation treatment amd during subsequent chilled storage also aided differentiation of irradiated and unirradiated birds. Large numbers of yeast and Gram positive cocci were isolated from irradiated carcasses whereas Gram negative oxidative rods were the predominant spoilage flora on unirradiated birds. (author)

  3. Evaluation of the Limulus amoebocyte lysate test in conjunction with a gram negative bacterial plate count for detecting irradiation of chicken

    Energy Technology Data Exchange (ETDEWEB)

    Scotter, S.L.; Wood, R.; McWeeny, D.J. (Ministry of Agriculture, Fisheries and Food, Norwich (UK). Food Science Lab.)

    1990-01-01

    A study to evaluate the potential of the Limulus amoebocyte lysate (LAL) test in conjunction with a Gram negative bacterial (GNB) plate count for detecting the irradiation of chicken is described. Preliminary studies demonstrated that chickens irradiated at an absorbed dose of 2.5 kGy could be differentiated from unirradiated birds by measuring levels of endotoxin and of numbers of GNB on chicken skin. Irradiated birds were found to have endotoxin levels similar to those found in unirradiated birds but significantly lower numbers of GNB. In a limited study the test was found to be applicable to birds from different processors. The effect of temperature abuse on the microbiological profile, and thus the efficacy of the test, was also investigated. After temperature abuse, the irradiated birds were identifiable at worst up to 3 days after irradiation treatment at the 2.5 kGy level and at best some 13 days after irradiation. Temperature abuse at 15{sup 0}C resulted in rapid recovery of surviving micro-organisms which made differentiation of irradiated and unirradiated birds using this test unreliable. The microbiological quality of the bird prior to irradiation treatment also affected the test as large numbers of GNB present on the bird prior to irradiation treatment resulted in larger numbers of survivors. In addition, monitoring the developing flora after irradiation treatment amd during subsequent chilled storage also aided differentiation of irradiated and unirradiated birds. Large numbers of yeast and Gram positive cocci were isolated from irradiated carcasses whereas Gram negative oxidative rods were the predominant spoilage flora on unirradiated birds. (author).

  4. Comparison of in-house and commercial real time-PCR based carbapenemase gene detection methods in Enterobacteriaceae and non-fermenting gram-negative bacterial isolates.

    Science.gov (United States)

    Smiljanic, M; Kaase, M; Ahmad-Nejad, P; Ghebremedhin, B

    2017-07-10

    Carbapenemase-producing gram-negative bacteria are increasing globally and have been associated with outbreaks in hospital settings. Thus, the accurate detection of these bacteria in infections is mandatory for administering the adequate therapy and infection control measures. This study aimed to establish and evaluate a multiplex real-time PCR assay for the simultaneous detection of carbapenemase gene variants in gram-negative rods and to compare the performance with a commercial RT-PCR assay (Check-Direct CPE). 116 carbapenem-resistant Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii isolates were genotyped for carbapenemase genes by PCR and sequencing. The defined isolates were used for the validation of the in-house RT-PCR by use of designed primer pairs and probes. Among the carbapenem-resistant isolates the genes bla KPC , bla VIM , bla NDM or bla OXA were detected. Both RT-PCR assays detected all bla KPC , bla VIM and bla NDM in the isolates. The in-house RT-PCR detected 53 of 67 (79.0%) whereas the commercial assay detected only 29 (43.3%) of the OXA genes. The in-house sufficiently distinguished the most prevalent OXA types (23-like and 48-like) in the melting curve analysis and direct detection of the genes from positive blood culture vials. The Check-Direct CPE and the in-house RT-PCR assay detected the carbapenem resistance from solid culture isolates. Moreover, the in-house assay enabled the identification of carbapenemase genes directly from positive blood-culture vials. However, we observed insufficient detection of various OXA genes in both assays. Nevertheless, the in-house RT-PCR detected the majority of the OXA type genes in Enterobacteriaceae and A. baumannii.

  5. 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.

  6. [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.

  7. CHROMagar COL-APSE: a selective bacterial culture medium for the isolation and differentiation of colistin-resistant Gram-negative pathogens.

    Science.gov (United States)

    Abdul Momin, Muhd Haziq F; Bean, David C; Hendriksen, Rene S; Haenni, Marisa; Phee, Lynette M; Wareham, David W

    2017-11-01

    A selective chromogenic culture medium for the laboratory isolation and differentiation of colistin resistant Acinetobacter, Pseudomonas, Stenotrophomonas and Enterobacteriaceae spp. (CHROMagar COL-APSE) was developed, evaluated and compared to an existing selective bacterial culture medium (SuperPolymyxin). The medium was challenged with 84 isolates, including polymyxin B (POL B)-susceptible and -resistant type strains and colistin (COL)-resistant organisms recovered from human and animal samples. Susceptibility to COL and POL B was determined by agar dilution and broth microtitre dilution. The lower limit for the detection of COL-resistant organisms was also calculated for both CHROMagar COL-APSE and SuperPolymyxin media. The ability to isolate and correctly differentiate COL-resistant organisms within mixed cultures was also assessed and compared using both media. Using CHROMagar COL-APSE, Gram-negative pathogens (n=71) with intrinsic (n=8) or acquired COL (n=63) resistance were recovered with 100 % specificity down to the lower limit of detection of 10 1 colony-forming units (c.f.u.). The growth on SuperPolymyxin was similar, but notably weaker for COL-resistant non-fermentative bacteria (Acinetobacter, Pseudomonas and Stenotrophomonas). CHROMagar COL-APSE was also more sensitive in supporting the growth of Enterobacteriaceae with COL resistance associated with the carriage of mcr-1. CHROMagar COL-APSE is a sensitive and specific medium for the growth of COL-resistant bacterial pathogens. Due to the low limit of detection (10 1  c.f.u.), it may be useful as a primary isolation medium in the surveillance and recovery of COL-resistant bacteria from complex human, veterinary and environmental samples, especially those with plasmid-mediated MCR-1 or novel mechanisms of polymyxin resistance.

  8. Protecting Gram-negative bacterial cell envelopes from human lysozyme: Interactions with Ivy inhibitor proteins from Escherichia coli and Pseudomonas aeruginosa.

    Science.gov (United States)

    Liu, Zhihong; García-Díaz, Beatriz; Catacchio, Bruno; Chiancone, Emilia; Vogel, Hans J

    2015-11-01

    Lysozymes play an important role in host defense by degrading peptidoglycan in the cell envelopes of pathogenic bacteria. Several Gram-negative bacteria can evade this mechanism by producing periplasmic proteins that inhibit the enzymatic activity of lysozyme. The Escherichia coli inhibitor of vertebrate lysozyme, Ivyc and its Pseudomonas aeruginosa homolog, Ivyp1 have been shown to be potent inhibitors of hen egg white lysozyme (HEWL). Since human lysozyme (HL) plays an important role in the innate immune response, we have examined the binding of HL to Ivyc and Ivyp1. Our results show that Ivyp1 is a weaker inhibitor of HL than Ivyc even though they inhibit HEWL with similar potency. Calorimetry experiments confirm that Ivyp1 interacts more weakly with HL than HEWL. Analytical ultracentrifugation studies revealed that Ivyp1 in solution is a monomer and forms a 30kDa heterodimer with both HL and HEWL, while Ivyc is a homodimer that forms a tetramer with both enzymes. The interaction of Ivyp1 with HL was further characterized by NMR chemical shift perturbation experiments. In addition to the characteristic His-containing Ivy inhibitory loop that binds into the active site of lysozyme, an extended loop (P2) between the final two beta-strands also participates in forming protein-protein interactions. The P2 loop is not conserved in Ivyc and it constitutes a flexible region in Ivyp1 that becomes more rigid in the complex with HL. We conclude that differences in the electrostatic interactions at the binding interface between Ivy inhibitors and distinct lysozymes determine the strength of this interaction. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. 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

  10. 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.

  11. A multi-label classifier for predicting the subcellular localization of gram-negative bacterial proteins with both single and multiple sites.

    Directory of Open Access Journals (Sweden)

    Xuan Xiao

    Full Text Available Prediction of protein subcellular localization is a challenging problem, particularly when the system concerned contains both singleplex and multiplex proteins. In this paper, by introducing the "multi-label scale" and hybridizing the information of gene ontology with the sequential evolution information, a novel predictor called iLoc-Gneg is developed for predicting the subcellular localization of gram-positive bacterial proteins with both single-location and multiple-location sites. For facilitating comparison, the same stringent benchmark dataset used to estimate the accuracy of Gneg-mPLoc was adopted to demonstrate the power of iLoc-Gneg. The dataset contains 1,392 gram-negative bacterial proteins classified into the following eight locations: (1 cytoplasm, (2 extracellular, (3 fimbrium, (4 flagellum, (5 inner membrane, (6 nucleoid, (7 outer membrane, and (8 periplasm. Of the 1,392 proteins, 1,328 are each with only one subcellular location and the other 64 are each with two subcellular locations, but none of the proteins included has pairwise sequence identity to any other in a same subset (subcellular location. It was observed that the overall success rate by jackknife test on such a stringent benchmark dataset by iLoc-Gneg was over 91%, which is about 6% higher than that by Gneg-mPLoc. As a user-friendly web-server, iLoc-Gneg is freely accessible to the public at http://icpr.jci.edu.cn/bioinfo/iLoc-Gneg. Meanwhile, a step-by-step guide is provided on how to use the web-server to get the desired results. Furthermore, for the user's convenience, the iLoc-Gneg web-server also has the function to accept the batch job submission, which is not available in the existing version of Gneg-mPLoc web-server. It is anticipated that iLoc-Gneg may become a useful high throughput tool for Molecular Cell Biology, Proteomics, System Biology, and Drug Development.

  12. Prevalence of carbapenem-resistant organisms and other Gram-negative MDRO in German ICUs: first results from the national nosocomial infection surveillance system (KISS).

    Science.gov (United States)

    Maechler, F; Peña Diaz, L A; Schröder, C; Geffers, C; Behnke, M; Gastmeier, P

    2015-04-01

    Standardized prevalence and incidence data on carbapenem-resistant organisms (CRO) and, as a relevant subgroup, carbapenem-resistant Enterobacteriaceae (CRE) are scarce. CRO-surveillance within the German nosocomial infection surveillance system (KISS) aims to provide epidemiological surveillance data on CRO colonizations and infections. CRO-surveillance is part of a KISS-module for the surveillance of multidrug-resistant organisms (MDRO). MDRO-KISS methods require surveillance of all patients admitted to the ward and standardized documentation of imported and ICU-acquired cases. Data on all MDRO-carriers including colonization and infection with MDRO are collected. All presented data were routine data collected from January 1st 2013 until December 1st 2013 in accordance with the German Protection against Infection Act (IfSG). 341 ICUs submitted data on MDRO during the first year. In total, 5,171 cases of multidrug-resistant Gram-negative bacteria (MRGN) were identified. 848 were CRO (16%). 325 CRO-cases were acquired within the ICU (38%), and 373 CRO-patients had an infection (44%). CRO-prevalence was 0.29 per 100 patients. Acquisition rate of MRGN was 1.32 per 1,000 patient days. This rate is more than doubled the acquisition rates of other MDRO under surveillance within MDRO-KISS (0.57 MRSA, 0.49 VRE). CRO-acquisition rate was 0.3 per 1,000 patient days. Incidence density of MRGN infections bacteria was 0.58 per 1,000 patient days (CRO 0.15/1,000 patient days). To date, CRO are common in German ICUs and the relatively large proportions of ICU-acquired CRO and infections emphasize their potential to cause outbreaks. High MRGN infection rates and high ESBL prevalence data from clinical studies suggest a lack of MRGN identification in asymptomatic carriers.

  13. High Rate of Multidrug-Resistant Gram-Negative Bacilli Carriage and Infection in Hospitalized Returning Travelers: A Cross-Sectional Cohort Study.

    Science.gov (United States)

    Epelboin, Loïc; Robert, Jérôme; Tsyrina-Kouyoumdjian, Ellina; Laouira, Sonia; Meyssonnier, Vanina; Caumes, Eric

    2015-01-01

    Carriage of and infection with multidrug-resistant Gram-negative bacilli (MDR-GNB) are a potential cause of concern in travelers with no history of hospitalization abroad. All consecutive returning travelers hospitalized in our department between February 2012 and January 2013 were prospectively screened for MDR-GNB gastrointestinal tract carriage or infection. We compared the prevalence of MDR-GNB in travelers to a non-travelers nonexposed group. Then among the travelers, MDR-GNB carriers were compared to noncarriers to determine risk factors of acquisition of MDR-GNB. Overall, 359 patients (191 travelers, 168 non-travelers) were included, and 25 (6.4%), including 23 travelers, harbored MDR-GNB. Five travelers had an MDR-GNB infection while 18 were asymptomatic enteric carriers. MDR-GNB carriage or infection was significantly more frequent in travelers (11.0% vs 1.2% for non-travelers, odds ratio (OR) = 11.3, p < 0.001) and in patients born outside France (OR = 1.67; p = 0.03). Among travelers, in multivariate analysis, factors independently associated with MDR-GNB carriage or infection were traveling to Asia (OR = 3.1; p = 0.01) and visiting friends and relatives (VFR) or migrants (OR=3.6; p = 0.01). The 10-fold higher prevalence rate of MDR-GNB in travelers raises the issues of systematic screening of all travelers, and of the choice of first line antibiotic therapy when treating urinary tract infections in travelers, especially those VFR, migrants, and those returning from Asia. © 2015 International Society of Travel Medicine.

  14. 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

  15. Rapid Identification of Bacterial Antibiotic Resistance by qPCR in Infants with Gram-Negative Septicaemia: A Proof-of-Concept Study.

    Science.gov (United States)

    Lam, Hugh Simon; Chan, Kathy Y Y; Ip, Margaret; Leung, Kam Tong; Lo, Norman W S; Wong, Raymond P O; Li, Karen; Ng, Pak Cheung

    2017-01-01

    Neonatal sepsis remains an important cause of neonatal morbidity and mortality. Tools to rapidly predict antibiotic resistance in neonatal sepsis would be extremely valuable. To develop quantitative polymerase chain reaction (qPCR) primer/probe sets that can rapidly detect antibiotic resistance genes common to a neonatal unit, and to investigate the feasibility of direct detection of antibiotic resistance genes in whole blood of infants with Gram-negative septicaemia without first isolating the organism. Primer/probe sets were designed to detect genes that produce aminoglycoside-modifying enzymes or extended-spectrum β-lactamase. In phase 1, Gram-negative organisms isolated from neonatal clinical specimens within a 12-month period were analysed by qPCR to detect preselected genes. In phase 2, blood specimens of infants with Gram-negative septicaemia were subjected to qPCR analysis to detect antibiotic resistance genes for comparison against conventional antibiotic resistance profile results. Two primer/probe sets showed promising diagnostic utilities for the prediction of antibiotic resistance; the diagnostic utilities (sensitivity, specificity, positive predictive value and negative predictive value) were 90.9, 96.4, 92.6 and 95.5%, respectively, for AAC3-2 [aac(3')-IIa/aacC3/aacC2, aac(3')-IIc/aacC2] to detect gentamicin resistance, and 59.3, 99.3, 94.1 and 92.6%, respectively, for BLA-C1 (blaCTX-M-9, blaCTX-M-14, blaCTX-M-24, blaCTX-M-27) to detect cephalosporin resistance. Twenty-six infants were tested in phase 2, and both gentamicin and cephalosporin resistance patterns were predicted with 100% sensitivity and 100% specificity by AAC3-2 and BLA-C1, respectively. qPCR with appropriately designed primer/probe sets can predict antibiotic resistance directly from neonatal blood, and it can substantially reduce the turnaround time for antibiotic resistance results. © 2016 S. Karger AG, Basel.

  16. Respiratory bacterial infections in cystic fibrosis

    DEFF Research Database (Denmark)

    Ciofu, Oana; Hansen, Christine R; Høiby, Niels

    2013-01-01

    PURPOSE OF REVIEW: Bacterial respiratory infections are the main cause of morbidity and mortality in patients with cystic fibrosis (CF). Pseudomonas aeruginosa remains the main pathogen in adults, but other Gram-negative bacteria such as Achromobacter xylosoxidans and Stenotrophomonas maltophilia...

  17. Caprolactam-silica network, a strong potentiator of the antimicrobial activity of kanamycin against gram-positive and gram-negative bacterial strains.

    Science.gov (United States)

    Voicu, Georgeta; Grumezescu, Valentina; Andronescu, Ecaterina; Grumezescu, Alexandru Mihai; Ficai, Anton; Ficai, Denisa; Ghitulica, Cristina Daniela; Gheorghe, Irina; Chifiriuc, Mariana Carmen

    2013-03-25

    Here, we report the fabrication of a novel ε-caprolactam-silica (ε-SiO2) network and assessed its biocompatibility and ability to improve the antimicrobial activity of kanamycin. The results of the quantitative antimicrobial assay demonstrate that the obtained ε-SiO2 network has efficiently improved the kanamycin activity on Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 strains, with a significant decrease of the minimum inhibitory concentration. The ε-SiO2 network could be feasibly obtained and represents an alternative for the design of new antibiotic drug carriers or delivery systems to control bacterial infections. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Growth of Ag-nanoparticles in an aqueous solution and their antimicrobial activities against Gram positive, Gram negative bacterial strains and Candida fungus.

    Science.gov (United States)

    Aazam, Elham Shafik; Zaheer, Zoya

    2016-04-01

    Silver nanoparticles (AgNPs) were synthesized using Ocimum sanctum (Tulsi) leaves aqueous extract as reducing as well as a capping agent in absence and presence of cetyltrimethylammonium bromide (CTAB). The resulting nanomaterials were characterized by UV-visible spectrophotometer, and transmission electron microscope. The UV-Vis spectroscopy revealed the formation of AgNPs at 400-450 nm. TEM photographs indicate that the truncated triangular silver nanoplates and/or spherical morphology of the AgNPs with an average diameter of 25 nm have been distorted markedly in presence of CTAB. The AgNPs were almost mono disperse in nature. Antimicrobial activities of AgNPs were determined by using two bacteria (Gram positive Staphylococcus aureus MTCC-3160), Gram negative Escherichia coli MTCC-450) and one species of Candida fungus (Candida albicans ATCC 90030) with Kirby-Bauer or disc diffusion method. The zone of inhibition seems extremely good showing a relatively large zone of inhibition in both Staphylococcus aureus, Escherichia coli, and Candida albicans strains.

  19. 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.

  20. 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.

  1. In vivo metabolism of 2,2'-diaminopimelic acid from gram-positive and gram-negative bacterial cells by ruminal microorganisms and ruminants and its use as a marker of bacterial biomass

    International Nuclear Information System (INIS)

    Masson, H.A.; Denholm, A.M.; Ling, J.R.

    1991-01-01

    Cells of Bacillus megaterium GW1 and Escherichia coli W7-M5 were specifically radiolabeled with 2,2'-diamino [G- 3 H] pimelic acid ([ 3 H]DAP) as models of gram-positive and gram-negative bacteria, respectively. Two experiments were conducted to study the in vivo metabolism of 2,2'-diaminopimelic acid (DAP) in sheep. In experiment 1, cells of [ 3 H]DAP-labeled B. megaterium GW1 were infused into the rumen of one sheep and the radiolabel was traced within microbial samples, digesta, and the whole animal. Bacterially bound [ 3 H]DAP was extensively metabolized, primarily (up to 70% after 8 h) via decarboxylation to [ 3 H]lysine by both ruminal protozoa and ruminal bacteria. Recovery of infused radiolabel in urine and feces was low (42% after 96 h) and perhaps indicative of further metabolism by the host animal. In experiment 2, [ 3 H]DAP-labeled B. megaterium GW1 was infused into the rumens of three sheep and [ 3 H]DAP-labeled E. coli W7-W5 was infused into the rumen of another sheep. The radioactivity contents of these mutant bacteria were insufficient to use as tracers, but the metabolism of DAP was monitored in the total, free, and peptidyl forms. Free DAP, as a proportion of total DPA in duodenal digesta, varied from 0 to 9.5%, whereas peptidyl DAP accounted for 8.3 to 99.2%

  2. CHROMagar COL-APSE: a selective bacterial culture medium for the isolation and differentiation of colistin-resistant Gram-negative pathogens

    DEFF Research Database (Denmark)

    Abdul Momin, Muhd Haziq F; Bean, David C; Hendriksen, Rene S.

    2017-01-01

    Purpose. A selective chromogenic culture medium for the laboratory isolation and differentiation of colistin resistant Acinetobacter, Pseudomonas, Stenotrophomonas and Enterobacteriaceae spp. (CHROMagar COL-APSE) was developed, evaluated and compared to an existing selective bacterial culture...

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  5. 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.

  6. CHROMagar COL-APSE: a selective bacterial culture medium for the isolation and differentiation of colistin-resistant Gram-negative pathogens

    DEFF Research Database (Denmark)

    Abdul Momin, Muhd Haziq F; Bean, David C; Hendriksen, Rene S.

    2017-01-01

    Purpose. A selective chromogenic culture medium for the laboratory isolation and differentiation of colistin resistant Acinetobacter, Pseudomonas, Stenotrophomonas and Enterobacteriaceae spp. (CHROMagar COL-APSE) was developed, evaluated and compared to an existing selective bacterial culture...... for the growth of COL-resistant bacterial pathogens. Due to the low limit of detection (101 c.f.u.), it may be useful as a primary isolation medium in the surveillance and recovery of COL-resistant bacteria from complex human, veterinary and environmental samples, especially those with plasmid-mediated MCR-1...... medium (SuperPolymyxin). Methodology. The medium was challenged with 84 isolates, including polymyxin B (POL B)-susceptible and -resistant type strains and colistin (COL)-resistant organisms recovered from human and animal samples. Susceptibility to COL and POL B was determined by agar dilution and broth...

  7. 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...

  8. 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.

  9. 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.

  10. 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.

  11. Results of the national surveillance of antimicrobial resistance of Enterobacteriaceae and Gram negative bacilli in health care-associated infections in Colombia, 2012-2014

    Directory of Open Access Journals (Sweden)

    María Victoria Ovalle

    2017-12-01

    Conclusion: The data from the surveillance of healthcare-associated infections revealed significant carbapenem resistance profiles and antimicrobial resistance mechanisms circulating in Colombian healthcare institutions.

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

    DEFF Research Database (Denmark)

    Knudsen, Inge Jenny Dahl; Andersen, Stig Ejdrup

    2014-01-01

    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...

  13. High prevalence of hospital-acquired infections caused by gram-negative carbapenem resistant strains in Vietnamese pediatric ICUs: A multi-centre point prevalence survey

    NARCIS (Netherlands)

    Le, N.K.; Wertheim, H.F.L.; Vu, P.D.; Khu, D.T.; Le, H.T.; Hoang, B.T.; Vo, V.T.; Lam, Y.M.; Vu, D.T.; Nguyen, Thanh Son; Thai, T.Q.; Nilsson, L.E.; Rydell, U.; Nguyen, K.V.; Nadjm, B.; Clarkson, L.; Hanberger, H.; Larsson, M.

    2016-01-01

    There is scarce information regarding hospital-acquired infections (HAIs) among children in resource-constrained settings. This study aims to measure prevalence of HAIs in Vietnamese pediatric hospitals.Monthly point prevalence surveys (PPSs) in 6 pediatric intensive care units (ICUs) in 3 referral

  14. 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...

  15. In vitro activity of aminoglycosides against clinical isolates of Acinetobacter baumannii complex and other nonfermentative Gram-negative bacilli causing healthcare-associated bloodstream infections in Taiwan.

    Science.gov (United States)

    Liu, Jyh-You; Wang, Fu-Der; Ho, Mao-Wang; Lee, Chen-Hsiang; Liu, Jien-Wei; Wang, Jann-Tay; Sheng, Wang-Huei; Hseuh, Po-Ren; Chang, Shan-Chwen

    2016-12-01

    Aminoglycosides possess in vitro activity against aerobic and facultative Gram-negative bacilli. However, nationwide surveillance on susceptibility data of Acinetobacter baumannii complex and Pseudomonas aeruginosa to aminoglycosides was limited, and aminoglycoside resistance has emerged in the past decade. We study the in vitro susceptibility of A. baumannii complex and other nonfermentative Gram-negative bacilli (NFGNB) to aminoglycosides. A total of 378 NFGNB blood isolates causing healthcare-associated bloodstream infections during 2008 and 2013 at four medical centers in Taiwan were tested for their susceptibilities to four aminoglycosides using the agar dilution method (gentamicin, amikacin, tobramycin, and isepamicin) and disc diffusion method (isepamicin). A. baumannii was highly resistant to all four aminoglycosides (range of susceptibility, 0-4%), whereas >80% of Acinetobacter nosocomialis and Acinetobacter pittii blood isolates were susceptible to amikacin (susceptibility: 96% and 91%, respectively), tobramycin (susceptibility: 92% and 80%, respectively), and isepamicin (susceptibility: 96% and 80%, respectively). All aminoglycosides except gentamicin possessed good in vitro activity (>94%) against P. aeruginosa. Amikacin has the best in vitro activity against P. aeruginosa (susceptibility, 98%), followed by A. nosocomialis (96%), and A. pittii (91%), whereas tobramycin and isepamicin were less potent against A. pittii (both 80%). Aminoglycoside resistances were prevalent in Stenotrophomonas maltophilia and Burkholderia cepacia complex blood isolates in Taiwan. Genospecies among the A. baumannii complex had heterogeneous susceptibility profiles to aminoglycosides. Aminoglycosides, except gentamicin, remained good in vitro antimicrobial activity against P. aeruginosa. Further in vivo clinical data and continuous resistance monitoring are warranted for clinical practice guidance. Copyright © 2015. Published by Elsevier B.V.

  16. 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.

  17. 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.

  18. 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.

  19. Characteristics of gram-negative urinary tract infections caused by extended spectrum beta lactamases: pivmecillinam as a treatment option within South Dublin, Ireland

    Directory of Open Access Journals (Sweden)

    Fardod O’Kelly

    2016-11-01

    Full Text Available Abstract Background The prevalence of urinary tract infections (UTIs caused by extended-spectrum β-lactamase (ESBL-producing Enterobacteriaceae is increasing and the therapeutic options are limited, especially in primary care. Recent indications have suggested pivmecillinam to be a suitable option. This pilot study aimed to assess the viability of pivmecillinam as a therapeutic option in a Dublin cohort of mixed community and healthcare origin. Methods A prospective measurement of mean and fractional inhibitory concentrations of antibiotic use in 95 patients diagnosed with UTI caused by ESBL-producing Enterobacteriaceae was carried out. 36 % patients were from general practice, 40 % were admitted to hospital within south Dublin, and 25 % samples arose from nursing homes. EUCAST breakpoints were used to determine if an isolate was sensitive or resistant to antibiotic agents. Results Sixty-nine percent of patients (N = 66 with urinary ESBL isolates were female. The mean age of females was 66 years compared with a mean age of 74 years for males. Thirty-six percent of isolates originated from primary care, hospital inpatients (26 %, and nursing homes (24 %. The vast majority of ESBL isolates were E. coli (80 %. The E tests for mecillinam and co-amoxiclav had concentration ranges from 0.16 mg/L up to 256 mg/L. The mean inhibitory concentration (MIC of mecillinam ranged from 0.25 to 256 mg/L, while co-amoxiclav MICs ranged from 6 to 256 mg/L. The percentage of isolates resistant to mecillinam and co-amoxiclav was found to be 5.26 and 94.74 % respectively. Conclusions This is the first study exploring the use of pivmecillinam in an Irish cohort and has demonstrated that its use in conjunction with or without co-amoxiclav is an appropriate and useful treatment for urinary tract infections caused by ESBL-producing organisms.

  20. 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.

  1. Comprehensive Evaluation of the MBT STAR-BL Module for Simultaneous Bacterial Identification and β-Lactamase-Mediated Resistance Detection in Gram-Negative Rods from Cultured Isolates and Positive Blood Cultures.

    Science.gov (United States)

    Lee, Annie W T; Lam, Johnson K S; Lam, Ricky K W; Ng, Wan H; Lee, Ella N L; Lee, Vicky T Y; Sze, Po P; Rajwani, Rahim; Fung, Kitty S C; To, Wing K; Lee, Rodney A; Tsang, Dominic N C; Siu, Gilman K H

    2018-01-01

    Objective: This study evaluated the capability of a MALDI Biotyper system equipped with the newly introduced MBT STAR-BL module to simultaneously perform species identification and β-lactamase-mediated resistance detection in bacteremia -causing bacteria isolated from cultured isolates and patient-derived blood cultures (BCs). Methods: Two hundred retrospective cultured isolates and 153 prospective BCs containing Gram-negative rods (GNR) were collected and subjected to direct bacterial identification, followed by the measurement of β-lactamase activities against ampicillin, piperacillin, cefotaxime, ceftazidime, and meropenem using the MBT STAR-BL module. The results and turnaround times were compared with those of routine microbiological processing. All strains were also characterized by beta-lactamase PCR and sequencing. Results: Using the saponin-based extraction method, MALDI-TOF MS correctly identified bacteria in 116/134 (86.6%) monomicrobial BCs. The detection sensitivities for β-lactamase activities against ampicillin, piperacillin, third-generation cephalosporin and meropenem were 91.3, 100, 97.9, and 100% for cultured isolates, and 80.4, 100, 68.8, and 40% for monomicrobial BCs ( n = 134) respectively. The overall specificities ranged from 91.5 to 100%. Furthermore, the MBT STAR-BL and conventional drug susceptibility test results were concordant in 14/19 (73.7%) polymicrobial cultures. Reducing the logRQ cut-off value from 0.4 to 0.2 increased the direct detection sensitivities for β-lactamase activities against ampicillin, cefotaxime and meropenem in BCs to 85.7, 87.5, and 100% respectively. The MBT STAR-BL test enabled the reporting of β-lactamase-producing GNR at 14.16 and 47.64 h before the interim and final reports of routine BCs processing, respectively, were available. Conclusion: The MALDI Biotyper system equipped with the MBT STAR-BL module enables the simultaneous rapid identification of bacterial species and

  2. Multicentre open-label randomised controlled trial to compare colistin alone with colistin plus meropenem for the treatment of severe infections caused by carbapenem-resistant Gram-negative infections (AIDA): a study protocol.

    Science.gov (United States)

    Dickstein, Yaakov; Leibovici, Leonard; Yahav, Dafna; Eliakim-Raz, Noa; Daikos, George L; Skiada, Anna; Antoniadou, Anastasia; Carmeli, Yehuda; Nutman, Amir; Levi, Inbar; Adler, Amos; Durante-Mangoni, Emanuele; Andini, Roberto; Cavezza, Giusi; Mouton, Johan W; Wijma, Rixt A; Theuretzbacher, Ursula; Friberg, Lena E; Kristoffersson, Anders N; Zusman, Oren; Koppel, Fidi; Dishon Benattar, Yael; Altunin, Sergey; Paul, Mical

    2016-04-20

    The emergence of antibiotic-resistant bacteria has driven renewed interest in older antibacterials, including colistin. Previous studies have shown that colistin is less effective and more toxic than modern antibiotics. In vitro synergy studies and clinical observational studies suggest a benefit of combining colistin with a carbapenem. A randomised controlled study is necessary for clarification. This is a multicentre, investigator-initiated, open-label, randomised controlled superiority 1:1 study comparing colistin monotherapy with colistin-meropenem combination therapy for infections caused by carbapenem-resistant Gram-negative bacteria. The study is being conducted in 6 centres in 3 countries (Italy, Greece and Israel). We include patients with hospital-associated and ventilator-associated pneumonia, bloodstream infections and urosepsis. The primary outcome is treatment success at day 14, defined as survival, haemodynamic stability, stable or improved respiratory status for patients with pneumonia, microbiological cure for patients with bacteraemia and stability or improvement of the Sequential Organ Failure Assessment (SOFA) score. Secondary outcomes include 14-day and 28-day mortality as well as other clinical end points and safety outcomes. A sample size of 360 patients was calculated on the basis of an absolute improvement in clinical success of 15% with combination therapy. Outcomes will be assessed by intention to treat. Serum colistin samples are obtained from all patients to obtain population pharmacokinetic models. Microbiological sampling includes weekly surveillance samples with analysis of resistance mechanisms and synergy. An observational trial is evaluating patients who met eligibility requirements but were not randomised in order to assess generalisability of findings. The study was approved by ethics committees at each centre and informed consent will be obtained for all patients. The trial is being performed under the auspices of an

  3. An In-Vitro Investigation of the Antibacterial Effects of the Acetone and Ethanol Extracts and the Supernatant of the Algae Chlorella vulgaris CCATM- 210-1 on Some of the Gram-Negative Bacterial Foodborne Pathogens

    OpenAIRE

    Yasaman Asadi; Monir Doudi; Behrouz Zarei Darki

    2016-01-01

    Algae are rich sources of amino acids, terpenoids, florentines, alkanes, halogenated ketones, steroidal compounds, fatty acids, and phenols that can be used in the pharmaceutical industry. The acetone and ethanol extracts, and the supernatant of the algae Chlorella vulgaris CCATM- 210-1, were used in this study. After culturing the Algae, and preparing the supernatant and extracts, the antibacterial effects of the extracts and supernatant of this algae against some of the gram-negative bacter...

  4. 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

  5. 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.

  6. 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...

  7. Tenebrio molitor Gram-negative-binding protein 3 (TmGNBP3) is essential for inducing downstream antifungal Tenecin 1 gene expression against infection with Beauveria bassiana JEF-007.

    Science.gov (United States)

    Yang, Yi-Ting; Lee, Mi Rong; Lee, Se Jin; Kim, Sihyeon; Nai, Yu-Shin; Kim, Jae Su

    2017-05-23

    The Toll signaling pathway is responsible for defense against both Gram-positive bacteria and fungi. Gram-negative binding protein 3 (GNBP3) has a strong affinity for the fungal cell wall component, β-1,3-glucan, which can activate the prophenoloxidase (proPO) cascade and induce the Toll signaling pathway. Myeloid differentiation factor 88 (MyD88) is an intracellular adaptor protein involved in the Toll signaling pathway. In this study, we monitored the response of 5 key genes (TmGNBP3, TmMyD88, and Tenecin 1, 2, and 3) in the Toll pathway of the mealworm Tenebrio molitor immune system against the fungus Beauveria bassiana JEF-007 using RT-PCR. TmGNBP3, Tenecin 1, and Tenecin 2 were significantly upregulated after fungal infection. To better understand the roles of the Toll signaling pathway in the mealworm immune system, TmGNBP3 and TmMyD88 were knocked down by RNAi silencing. Target gene expression levels decreased at 2 d postknockdown and were dramatically reduced at 6 d post-dsRNA injection. Therefore, mealworms were compromised by B. bassiana JEF-007 at 6 d post-dsRNA injection. Silencing of TmMyD88 and TmGNBP3 resulted in reduced resistance of the host to fungal infection. Particularly, reducing TmGNBP3 levels obviously downregulated Tenecin 1 and Tenecin 2 expression levels, whereas silencing TmMyD88 expression resulted in decreased Tenecin 2 expression. These results indicate that TmGNBP3 is essential to induce downstream antifungal peptide Tenecin 1 expression against B. bassiana JEF-007. © 2017 Institute of Zoology, Chinese Academy of Sciences.

  8. 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

  9. 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

  10. Surveillance of antimicrobial susceptibility of aerobic and facultative Gram-negative bacilli isolated from patients with intra-abdominal infections in China: the 2002-2009 Study for Monitoring Antimicrobial Resistance Trends (SMART).

    Science.gov (United States)

    Yang, Qiwen; Wang, Hui; Chen, Minjun; Ni, Yuxing; Yu, Yunsong; Hu, Bijie; Sun, Ziyong; Huang, Wenxiang; Hu, Yunjian; Ye, Huifen; Badal, Robert E; Xu, Yingchun

    2010-12-01

    The objective of this study was to investigate the distribution and susceptibility of aerobic and facultative Gram-negative bacilli (GNB) isolated from patients with intra-abdominal infections (IAIs) in China. From 2002 to 2009, minimum inhibitory concentrations of 14 antibiotics for 3420 aerobic and facultative GNB from up to eight hospitals in six cities were determined by the broth microdilution method. Enterobacteriaceae comprised 82.9% (2834/3420) of the total isolates, with Escherichia coli (49.2%) being the most commonly isolated species followed by Klebsiella pneumoniae (17.0%), Enterobacter cloacae (5.8%) and Citrobacter freundii (2.3%). Amongst the antimicrobial agents tested, the three carbapenems (ertapenem, imipenem and meropenem) were the most active agents against Enterobacteriaceae, with susceptibility rates of 96.1-99.6% (2002-2009), 98.2-100% (2002-2009) and 99.6-100% (2002-2004), respectively, followed by amikacin (86.8-95.1%) and piperacillin/tazobactam (84.5-94.3%). Susceptibility rates of all tested third- and fourth-generation cephalosporins against Enterobacteriaceae declined by nearly 30%, with susceptibility rates of 40.2%, 39.1%, 56.3% and 51.8% in 2009 for ceftriaxone, cefotaxime, ceftazidime and cefepime, respectively. The occurrence of extended-spectrum β-lactamases increased rapidly, especially for E. coli (from 20.8% in 2002 to 64.9% in 2009). Susceptibility of E. coli to ciprofloxacin decreased from 57.6% in 2002 to 24.2% in 2009. The least active agent against Enterobacteriaceae was ampicillin/sulbactam (SAM) (25.3-44.3%). In conclusion, Enterobacteriaceae were the major pathogens causing IAIs, and carbapenems retained the highest susceptibility rates over the 8-year study period. Third- and fourth-generation cephalosporins, fluoroquinolones and SAM may not be ideal choices for empirical therapy of IAIs in China. Copyright © 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  11. 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

  12. Antimicrobial susceptibility of gram-negative pathogens isolated from patients with complicated intra-abdominal infections in South African hospitals (SMART Study 2004-2009): impact of the new carbapenem breakpoints.

    Science.gov (United States)

    Brink, Adrian J; Botha, Roelof F; Poswa, Xoliswa; Senekal, Marthinus; Badal, Robert E; Grolman, David C; Richards, Guy A; Feldman, Charles; Boffard, Kenneth D; Veller, Martin; Joubert, Ivan; Pretorius, Jan

    2012-02-01

    The Study for Monitoring Antimicrobial Resistance Trends (SMART) follows trends in resistance among aerobic and facultative anaerobic gram-negative bacilli (GNB) isolated from complicated intra-abdominal infections (cIAIs) in patients around the world. During 2004-2009, three centralized clinical microbiology laboratories serving 59 private hospitals in three large South African cities collected 1,218 GNB from complicated intra-abdominal infections (cIAIs) and tested them for susceptibility to 12 antibiotics according to the 2011 Clinical Laboratory Standards Institute (CLSI) guidelines. Enterobacteriaceae comprised 83.7% of the isolates. Escherichia coli was the species isolated most commonly (46.4%), and 7.6% of these were extended-spectrum β-lactamase (ESBL)-positive. The highest ESBL rate was documented for Klebsiella pneumoniae (41.2%). Overall, ertapenem was the antibiotic most active against susceptible species for which it has breakpoints (94.6%) followed by amikacin (91.9%), piperacillin-tazobactam (89.3%), and imipenem-cilastatin (87.1%), whereas rates of resistance to ceftriaxone, cefotaxime, ciprofloxacin, and levofloxacin were documented to be 29.7%, 28.7%, 22.5%, and 21.1%, respectively. Multi-drug resistance (MDR), defined as resistance to three or more antibiotic classes, was significantly more common in K. pneumoniae (27.9%) than in E. coli (4.9%; p<0.0001) or Proteus mirabilis (4.1%; p<0.05). Applying the new CLSI breakpoints for carbapenems, susceptibility to ertapenem was reduced significantly in ESBL-positive E. coli compared with ESBL-negative isolates (91% vs. 98%; p<0.05), but this did not apply to imipenem-cilastatin (95% vs. 99%; p=0.0928). A large disparity between imipenem-cilastatin and ertapenem susceptibility in P. mirabilis and Morganella morganii was documented (24% vs. 96% and 15% vs. 92%, respectively), as most isolates of these two species had imipenem-cilastatin minimum inhibitory concentrations in the 2-4 mcg/mL range, which

  13. 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)

  14. 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.

  15. 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

  16. Role of quorum sensing in bacterial infections

    Science.gov (United States)

    Castillo-Juárez, Israel; Maeda, Toshinari; Mandujano-Tinoco, Edna Ayerim; Tomás, María; Pérez-Eretza, Berenice; García-Contreras, Silvia Julieta; Wood, Thomas K; García-Contreras, Rodolfo

    2015-01-01

    Quorum sensing (QS) is cell communication that is widely used by bacterial pathogens to coordinate the expression of several collective traits, including the production of multiple virulence factors, biofilm formation, and swarming motility once a population threshold is reached. Several lines of evidence indicate that QS enhances virulence of bacterial pathogens in animal models as well as in human infections; however, its relative importance for bacterial pathogenesis is still incomplete. In this review, we discuss the present evidence from in vitro and in vivo experiments in animal models, as well as from clinical studies, that link QS systems with human infections. We focus on two major QS bacterial models, the opportunistic Gram negative bacteria Pseudomonas aeruginosa and the Gram positive Staphylococcus aureus, which are also two of the main agents responsible of nosocomial and wound infections. In addition, QS communication systems in other bacterial, eukaryotic pathogens, and even immune and cancer cells are also reviewed, and finally, the new approaches proposed to combat bacterial infections by the attenuation of their QS communication systems and virulence are also discussed. PMID:26244150

  17. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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 ...

  5. 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

  6. 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

  7. 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:

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. 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.

  14. 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...

  15. 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, ...

  16. 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....

  17. 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 ...

  18. 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

  19. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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...

  6. 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

  7. Multidrug-Resistant Gram-Negative Bacterial and Carbapenem-Resistant Enterobacteriaceae Infections in the Department of the Navy: Annual Report 2013

    Science.gov (United States)

    2015-03-19

    as well, resulting in a wide range of resistance patterns including extensively drug -resistant (XDR) organisms, which are described below. 6 The...least three different antimicrobial categories deemed pertinent to a given species. Extensively drug -resistant isolates are non-susceptible to at least...presented by MDR organisms, which have the ability to confer resistance to other bacteria within and outside their respective genus to control the

  8. DMPD: Lipopolysaccharide sensing an important factor in the innate immune response toGram-negative bacterial infections: benefits and hazards of LPShypersensitivity. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available chet S, Keck S, Fejer G, Huber M, Schutze N, Beutler B,Galanos C. Immunobiology. 2008;213(3-4):193-203. Epub...ersensitivity. Authors Freudenberg MA, Tchaptchet S, Keck S, Fejer G, Huber M, Schutze N, Beutler B,Galanos C. Publication Immunobiol...ogy. 2008;213(3-4):193-203. Epub 2007 Dec 27. Pathway - PNG File (.png) SVG File (.

  9. Prevalence of Bacterial Vaginosis and Associated Risk Factors among Women Complaining of Genital Tract Infection

    Directory of Open Access Journals (Sweden)

    Adane Bitew

    2017-01-01

    Full Text Available Background. Bacterial vaginosis is a global concern due to the increased risk of acquisition of sexually transmitted infections. Objectives. To determine the prevalence of bacterial vaginosis and bacteria causing aerobic vaginitis. Methods. A cross-sectional study was conducted among 210 patients between September 2015 and July 2016 at St. Paul’s Hospital. Gram-stained vaginal swabs were examined microscopically and graded as per Nugent’s procedure. Bacteria causing aerobic vaginitis were characterized, and their antimicrobial susceptibility pattern was determined. Results. The overall prevalence of bacterial vaginosis was 48.6%. Bacterial vaginosis was significantly associated with number of pants used per day (p=0.001 and frequency of vaginal bathing (p=0.045. Of 151 bacterial isolates, 69.5% were Gram-negative and 30.5% were Gram-positive bacteria. The overall drug resistance level of Gram-positive bacteria was high against penicillin, tetracycline, and erythromycin. Cefoxitin and tobramycin were the most active drugs against Gram-positive bacteria. The overall drug resistance level of Gram-negative bacteria was high against tetracycline, ampicillin, and amoxicillin. Amikacin and tobramycin were the most active drugs against Gram-negative bacteria. Conclusions. The prevalence of bacterial vaginosis was high and was affected by individual hygiene. Routine culture of vaginal samples should be performed on patients with vaginitis and the drug susceptibility pattern of each isolate should be determined.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Vimentin in Bacterial Infections

    DEFF Research Database (Denmark)

    Mak, Tim N; Brüggemann, Holger

    2016-01-01

    filaments (IFs). IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge...... about the role of IFs in bacterial infections, focusing on the type III IF protein vimentin. Recent studies have revealed the involvement of vimentin in host cell defenses, acting as ligand for several pattern recognition receptors of the innate immune system. Two main aspects of bacteria......-vimentin interactions are presented in this review: the role of vimentin in pathogen-binding on the cell surface and subsequent bacterial invasion and the interaction of cytosolic vimentin and intracellular pathogens with regards to innate immune signaling. Mechanistic insight is presented involving distinct bacterial...

  15. [Bacterial biofilms and infection].

    Science.gov (United States)

    Lasa, I; Del Pozo, J L; Penadés, J R; Leiva, J

    2005-01-01

    In developed countries we tend to think of heart disease and the numerous forms of cancer as the main causes of mortality, but on a global scale infectious diseases come close, or may even be ahead: 14.9 million deaths in 2002 compared to cardiovascular diseases (16.9 million deaths) and cancer (7.1 million deaths) (WHO report 2004). The infectious agents responsible for human mortality have evolved as medical techniques and hygienic measures have changed. Modern-day acute infectious diseases caused by specialized bacterial pathogens such as diphtheria, tetanus, cholera, plague, which represented the main causes of death at the beginning of XX century, have been effectively controlled with antibiotics and vaccines. In their place, more than half of the infectious diseases that affect mildly immunocompromised patients involve bacterial species that are commensal with the human body; these can produce chronic infections, are resistant to antimicrobial agents and there is no effective vaccine against them. Examples of these infections are the otitis media, native valve endocarditis, chronic urinary infections, bacterial prostatitis, osteomyelitis and all the infections related to medical devices. Direct analysis of the surface of medical devices or of tissues that have been foci of chronic infections shows the presence of large numbers of bacteria surrounded by an exopolysaccharide matrix, which has been named the "biofilm". Inside the biofilm, bacteria grow protected from the action of the antibodies, phagocytic cells and antimicrobial treatments. In this article, we describe the role of bacterial biofilms in human persistent infections.

  16. Fluoroquinolones as imaging agents for bacterial infection.

    Science.gov (United States)

    Naqvi, Syed Ali Raza; Drlica, Karl

    2017-10-31

    Diagnosis of deep-seated bacterial infection is difficult, as neither standard anatomical imaging nor radiolabeled, autologous leukocytes distinguish sterile inflammation from infection. Two recent imaging efforts are receiving attention: (1) radioactive derivatives of sorbitol show good specificity with Gram-negative bacterial infections, and (2) success in combining anatomical and functional imaging for cancer diagnosis has rekindled interest in 99m Tc-fluoroquinolone-based imaging. With the latter, computed tomography (CT) would be combined with single-photon-emission-computed tomography (SPECT) to detect 99m Tc-fluoroquinolone-bacterial interactions. The present minireview provides a framework for advancing fluoroquinolone-based imaging by identifying gaps in our understanding of the process. One issue is the reliance of 99m Tc labeling on the reduction of sodium pertechnetate, which can lead to colloid formation and loss of specificity. Specificity problems may be reduced by altering the quinolone structure (for example, switching from ciprofloxacin to sitafloxacin). Another issue is the uncharacterized nature of 99m Tc-ciprofloxacin binding to, or sequestration in, bacteria: specific interactions with DNA gyrase, an intracellular fluoroquinolone target, are unlikely. Labeling with 68 Ga rather than 99m Tc enables detection by positron emission tomography, but with similar biological uncertainties. Replacing the C6-F of the fluoroquinolone with 18 F provides an alternative to pertechnetate and gallium that may lead to imaging based on drug interactions with gyrase. Gyrase-based imaging requires knowledge of fluoroquinolone action, which we update. We conclude that quinolone-based probes show promise for the diagnosis of infection, but improvements in specificity and sensitivity are needed. These improvements include the optimization of the quinolone structure; such chemistry efforts can be accelerated by refining microbiological assays.

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

    Directory of Open Access Journals (Sweden)

    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.

  18. 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 ...

  19. 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% ...

  20. 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.

  1. 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 ...

  2. 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 ...

  3. 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.

  4. 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.

  5. COEXISTENCE OF BACTERIAL INFECTION IN SPUTUM POSITIVE PULMONARY TUBERCULOSIS

    Directory of Open Access Journals (Sweden)

    Shashi Bhushan

    2015-12-01

    Full Text Available AIM AND OBJECTIVES To study the coexistence of bacterial infection among patients with confirmed sputum positive pulmonary tuberculosis. METHODS Study conducted at department of pulmonary medicine Victoria Hospital Bangalore, Karnataka, India, from January 2015 to June 2015 in confirmed positive sputum pulmonary tuberculosis patient, all patients were subjected for sputum gram staining and culture and sensitivity and checked for bacterial growth. RESULTS Total 150 patients were confirmed to have sputum positive pulmonary tuberculosis from January 2015 to June 2015 both inpatient and outpatient were subjected to undergo sputum gram stain and culture and sensitivity with the following growth Klebsiella 40% E coli 15.33% Pseudomonas 9.33% Pneumococci 4.66% gram negative non fermenters 2.66% methicillin resistant Staphylococcus aureus 1.33% Citrobacter 1.33% Enterobacter 1.33%, Serratia/Staphylococci aureus/Proteus .66%. CONCLUSION The most common secondary infection observed out of 150 patients is Klebsiella which is seen in 60 patients followed by E coli in 23 patients, pseudomonas in 14 patients Pneumococci in 7 pt gram negative non fermenter 4 pt, Methicillin resistant Staph aureus, Citrobacter, Enterobacter in 2 patients each Serratia, Proteus, Staphylococcus aureus in 1 patient each.

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

    Directory of Open Access Journals (Sweden)

    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.

  7. Current concepts in the management of bacterial skin infections in children

    Directory of Open Access Journals (Sweden)

    Palit Aparna

    2010-01-01

    Full Text Available Bacterial skin infections in children vary widely clinically, starting from mild superficial folliculitis to deep necrotizing fasciitis. The causative organisms are mostly Staphylococcus aureus and Streptococcus, with occasional involvement of Gram-negative organisms. Treatment of even the milder forms of bacterial skin infections is of importance because of the long-term morbidity associated with them. However, because of global emergence of resistant strains of bacteria, treatment of these conditions is becoming increasingly difficult. The current antibacterial resistance patterns in organisms causing skin and soft tissue infections and the problems encountered in their management in children have been discussed.

  8. 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...

  9. 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.

  10. Associations Between Timeliness of Therapy and Clinical and Economic Outcomes Among Patients With Serious Infections Due to Gram-negative Bacteria (GNB): How Much Does Delayed Appropriate Therapy (DAT) Matter?

    OpenAIRE

    Bonine, Nicole G; Berger, Ariel; Altincatal, Arman; Wang, Rosa; Bhagnani, Tarun; Gillard, Patrick; Lodise, Thomas

    2017-01-01

    Abstract Background Patients with serious GNB infections who receive DAT have worse outcomes. Most studies that have examined this issue include both antibiotic-resistant and susceptible pathogens. It is difficult to assign causality as DAT is correlated with resistance, which is associated with poorer prognosis. Our objective was to assess association between DAT and outcomes among patients with GNB infection, stratified by antibiotic susceptibility status. Methods Hospitalized adults betwee...

  11. 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...

  12. Diagnosis of bacterial infection

    African Journals Online (AJOL)

    rapid and easy-to-use test for bacterial infections. Clearly, this is a very ... detect antigens or specific antibodies, e.g. group A streptococcal antigen testing can be employed to reduce antibiotic use. Culture-based tests are often ... White blood cell count 12 000 cells/mm³; or the presence of >10% ...

  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

    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...

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. Prognostic factors and monomicrobial necrotizing fasciitis: gram-positive versus gram-negative pathogens

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    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.

  19. Update on bacterial nosocomial infections.

    Science.gov (United States)

    Bereket, W; Hemalatha, K; Getenet, B; Wondwossen, T; Solomon, A; Zeynudin, A; Kannan, S

    2012-08-01

    With increasing use of antimicrobial agents and advance in lifesaving medical practices which expose the patients for invasive procedures, are associated with the ever increasing of nosocomial infections. Despite an effort in hospital infection control measures, health care associated infections are associated with significant morbidity and mortality adding additional health care expenditure which may leads to an economic crisis. The problem is further complicated with the emergence of difficult to treat multidrug resistant (MDR) microorganism in the hospital environment. Virtually every pathogen has the potential to cause infection in hospitalized patients but only limited number of both gram positive and gram negative bacteria are responsible for the majority of nosocomial infection. Among them Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Enterococci takes the leading. Many intrinsic and extrinsic factors predispose hospitalized patients for these pathogens. Following simple hospital hygienic practices and strictly following standard medical procedures greatly reduces infection to a significant level although not all nosocomial infections are avoidable. The clinical spectrum caused by nosocomial pathogens depend on body site of infection, the involving pathogen and the patient's underlying condition. Structural and non structural virulence factors associated with the bacteria are responsible for the observed clinical manifestation. Bacteria isolation and characterization from appropriate clinical materials with antimicrobial susceptibility testing is the standard of laboratory diagnosis.

  20. 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.

  1. 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...

  2. 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

  3. Prevalência de sepse por bactérias Gram negativas produtoras de beta-lactamase de espectro estendido em Unidade de Cuidados Intensivos Neonatal Prevalence of extended-spectrum beta-lactamase producing Gram-negative bacterial sepsis in a Neonatal Intensive Care Unit

    Directory of Open Access Journals (Sweden)

    Carla Regina Tragante

    2008-03-01

    . Screening for ESBL was carried out following the National Committee for Clinical Laboratory Standards criteria. RESULTS: Eighty-four (36% neonates showed positive blood culture. Klebsiella pneumoniae was the most prevalent agent (47%. Among the neonates with Klebsiella pneumoniae infection, seven presented ESBL infection, with an infection rate of 0.4%. All the patients with one exception had length of hospital stay greater than 21 days and needed mechanical ventilation; all the newborns used central catheters, parenteral nutrition and broad-spectrum antibiotics. Among the 84 patients with confirmed sepsis, 36 (43% died and their blood cultures were positive for gram-negative bacteria (67% and fungous (19%. In relation to ESBL Klebsiella pneumoniae, three (43% neonates died. CONCLUSIONS: The prevalence of sepsis by ESBL Klebsiella pneumoniae was 0.4% and the mortality rate was 42.8%. It is important to detect and to control the spread of this infectious agent with its negative impact on the survival rate of premature and/or sick newborn infants.

  4. LpxC inhibitors as new antibacterial agents and tools for studying regulation of lipid A biosynthesis in Gram-negative pathogens.

    Science.gov (United States)

    Tomaras, Andrew P; McPherson, Craig J; Kuhn, Michael; Carifa, Arlene; Mullins, Lisa; George, David; Desbonnet, Charlene; Eidem, Tess M; Montgomery, Justin I; Brown, Matthew F; Reilly, Usa; Miller, Alita A; O'Donnell, John P

    2014-09-30

    The problem of multidrug resistance in serious Gram-negative bacterial pathogens has escalated so severely that new cellular targets and pathways need to be exploited to avoid many of the preexisting antibiotic resistance mechanisms that are rapidly disseminating to new strains. The discovery of small-molecule inhibitors of LpxC, the enzyme responsible for the first committed step in the biosynthesis of lipid A, represents a clinically unprecedented strategy to specifically act against Gram-negative organisms such as Pseudomonas aeruginosa and members of the Enterobacteriaceae. In this report, we describe the microbiological characterization of LpxC-4, a recently disclosed inhibitor of this bacterial target, and demonstrate that its spectrum of activity extends to several of the pathogenic species that are most threatening to human health today. We also show that spontaneous generation of LpxC-4 resistance occurs at frequencies comparable to those seen with marketed antibiotics, and we provide an in-depth analysis of the mechanisms of resistance utilized by target pathogens. Interestingly, these isolates also served as tools to further our understanding of the regulation of lipid A biosynthesis and enabled the discovery that this process occurs very distinctly between P. aeruginosa and members of the Enterobacteriaceae. Finally, we demonstrate that LpxC-4 is efficacious in vivo against multiple strains in different models of bacterial infection and that the major first-step resistance mechanisms employed by the intended target organisms can still be effectively treated with this new inhibitor. New antibiotics are needed for the effective treatment of serious infections caused by Gram-negative pathogens, and the responsibility of identifying new drug candidates rests squarely on the shoulders of the infectious disease community. The limited number of validated cellular targets and approaches, along with the increasing amount of antibiotic resistance that is

  5. Neglected pathogens: bacterial infections in persons with human immunodeficiency virus infection. A review of the literature (1).

    Science.gov (United States)

    Fish, D N; Danziger, L H

    1993-01-01

    Bacterial infections, including those that cause infection in the healthy host as well as those that are more opportunistic, occur very commonly among persons infected with the human immunodeficiency virus (HIV). Bacterial infections are a direct result of the severe humoral and cellular immune defects found in these patients. Epidemiologic factors such as intravenous drug use and stage of HIV infection may also play important roles. Pulmonary, bloodstream, gastrointestinal, central nervous system, skin and soft tissue, and catheter-related infections are common, as are endocarditis, prostatitis, and others. Frequently reported pathogens are common organisms such as Staphylococcus aureus, Haemophilus influenzae, Streptococcus pneumoniae, and enteric gram-negative pathogens, as well as less typical ones such as Listeria monocytogenes and Nocardia sp. The frequency of infection is specific to organ system and pathogen, often being many times higher than in immunocompetent hosts. Prompt recognition and aggressive therapy are required to reduce morbidity and mortality due to these infections.

  6. 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.

  7. 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.

  8. Bacterial feeding, Leishmania infection and distinct infection routes induce differential defensin expression in Lutzomyia longipalpis.

    Science.gov (United States)

    Telleria, Erich L; Sant'Anna, Maurício R Viana; Alkurbi, Mohammad O; Pitaluga, André N; Dillon, Rod J; Traub-Csekö, Yara M

    2013-01-11

    Phlebotomine insects harbor bacterial, viral and parasitic pathogens that can cause diseases of public health importance. Lutzomyia longipalpis is the main vector of visceral leishmaniasis in the New World. Insects can mount a powerful innate immune response to pathogens. Defensin peptides take part in this response and are known to be active against Gram-positive and Gram-negative bacteria, and some parasites. We studied the expression of a defensin gene from Lutzomyia longipalpis to understand its role in sand fly immune response. We identified, sequenced and evaluated the expression of a L. longipalpis defensin gene by semi-quantitative RT-PCR. The gene sequence was compared to other vectors defensins and expression was determined along developmental stages and after exposure of adult female L. longipalpis to bacteria and Leishmania. Phylogenetic analysis showed that the L. longipalpis defensin is closely related to a defensin from the Old World sand fly Phlebotomus duboscqi. Expression was high in late L4 larvae and pupae in comparison to early larval stages and newly emerged flies. Defensin expression was modulated by oral infection with bacteria. The Gram-positive Micrococcus luteus induced early high defensin expression, whilst the Gram-negative entomopathogenic Serratia marcescens induced a later response. Bacterial injection also induced defensin expression in adult insects. Female sand flies infected orally with Leishmania mexicana showed no significant difference in defensin expression compared to blood fed insects apart from a lower defensin expression 5 days post Leishmania infection. When Leishmania was introduced into the hemolymph by injection there was no induction of defensin expression until 72 h later. Our results suggest that L. longipalpis modulates defensin expression upon bacterial and Leishmania infection, with patterns of expression that are distinct among bacterial species and routes of infection.

  9. 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.

  10. 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.

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

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    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.

  12. 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.

  13. Detection of Extended Spectrum Beta-Lactamases Among Gram Negative Bacilli Recovered from Cattle Feces In Benin City, Nigeria

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    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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. Cefepime restriction improves gram-negative overall resistance patterns in neonatal intensive care unit

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    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.

  2. 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.

  3. [Development and Evaluation of a New Selective Culture Medium, KBM Anaero RS-GNR, for Detection of Anaerobic Gram Negative Rods].

    Science.gov (United States)

    Narita, Taeko; Kato, Kyohei; Hanaiwa, Hiroki; Harada, Tetsuhiro; Funashima, Yumiko; Akiwa, Makoto; Sekiguchi, Jun-Ichiro; Nagasawa, Zenzo; Umemura, Tsukuru

    2017-03-22

    The laboratory culture methods for isolating drug-resistant pathogens has been the gold standard in medical microbiology, and play pivotal roles in the overall management of infectious diseases. Recently, several reports have emphasized the development of antibiotics-resistance among anaerobic gram-negative rods, especially Genus Bacteroides and Prevotella . Therefore, a selective culture method to detect these pathogens is needed. We developed here the new selective culture medium, termed "KBM Anaero RS-GNR," for detecting anaerobic Gram-negative rods. Growth capability and selectivity of the agar medium were assessed by using the pure culture suspensions of more than 100 bacterial strains as well as the 13 samples experimentally contaminated with these bacterial strains. This new medium, "KBM Anaero RS-GNR," successfully showed the selective isolation of anaerobic Gram-negative rods. Compared with commercially available medium, "PV Brucella HK Agar, " which is also designed to detect anaerobic Gram-negative rods, there was no significant difference of the overall detection efficiency between two media. However, "KBM Anaero RS-GNR" showed superior to selectivity for anaerobic Gram-negative rods, especially from the samples contaminated with Candida species. Thus, the culture method using KBM Anaero RS-GNR is relevant for isolation of anaerobic Gram-negative rods especially from clinical specimens.

  4. 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...

  5. Bacterial diversity of symptomatic primary endodontic infection by clonal analysis

    Directory of Open Access Journals (Sweden)

    Letícia Maria Menezes NÓBREGA

    Full Text Available Abstract The aim of this study was to explore the bacterial diversity of 10 root canals with acute apical abscess using clonal analysis. Samples were collected from 10 patients and submitted to bacterial DNA isolation, 16S rRNA gene amplification, cloning, and sequencing. A bacterial genomic library was constructed and bacterial diversity was estimated. The mean number of taxa per canal was 15, ranging from 11 to 21. A total of 689 clones were analyzed and 76 phylotypes identified, of which 47 (61.84% were different species and 29 (38.15% were taxa reported as yet-uncultivable or as yet-uncharacterized species. Prevotella spp., Fusobacterium nucleatum, Filifactor alocis, and Peptostreptococcus stomatis were the most frequently detected species, followed by Dialister invisus, Phocaeicola abscessus, the uncharacterized Lachnospiraceae oral clone, Porphyromonas spp., and Parvimonas micra. Eight phyla were detected and the most frequently identified taxa belonged to the phylum Firmicutes (43.5%, followed by Bacteroidetes (22.5% and Proteobacteria (13.2%. No species was detected in all studied samples and some species were identified in only one case. It was concluded that acute primary endodontic infection is characterized by wide bacterial diversity and a high intersubject variability was observed. Anaerobic Gram-negative bacteria belonging to the phylum Firmicutes, followed by Bacteroidetes, were the most frequently detected microorganisms.

  6. Bacterial sensitivity to fosfomycin in pregnant women with urinary infection

    Directory of Open Access Journals (Sweden)

    Rodrigo Batista Souza

    2015-05-01

    Full Text Available The aim this study was to determine the in vitro susceptibility to fosfomycin of bacteria isolated from urine samples of pregnant women with urinary tract infection. Samples of urine culture with bacterial growth of pregnant women were collected from clinical laboratories in Tubarão, state of Santa Catarina, Brazil, between September 2012 and May 2013. In the experimental stage, the colonies were tested for sensitivity to fosfomycin by using the Kirby–Bauer method. The following information relating to the samples was also collected: patients’ age, colony count, type(s of identified bacterial(s and result of the antimicrobial sensitivity test. Student's t-test was used for mean comparison. A total of 134 samples were selected for the study. The age of the subjects ranged from 15 to 40 years (mean 26.7. Escherichia coli (Gram-negative and Staphylococcus aureus (Gram-positive were the most commonly identified species. In 89% of cases, the microorganisms were sensitive to fosfomycin. E. coli and S. aureus were the main species of bacteria responsible for urinary tract infections in women in the study area. The most prevalent microorganisms in pregnant women with urinary tract infection were susceptible to fosfomycin.

  7. Polymer-Ag nanocomposites with enhanced antimicrobial activity against bacterial infection.

    Science.gov (United States)

    Mei, Lin; Lu, Zhentan; Zhang, Xinge; Li, Chaoxing; Jia, Yanxia

    2014-09-24

    Herein, a nontoxic nanocomposite is synthesized by reduction of silver nitrate in the presence of a cationic polymer displaying strong antimicrobial activity against bacterial infection. These nanocomposites with a large concentration of positive charge promote their adsorption to bacterial membranes through electrostatic interaction. Moreover, the synthesized nanocomposites with polyvalent and synergistic antimicrobial effects can effectively kill both Gram-positive and Gram-negative bacteria without the emergence of bacterial resistance. Morphological changes obtained by transmission electron microscope observation show that these nanocomposites can cause leakage and chaos of intracellular contents. Analysis of the antimicrobial mechanism confirms that the lethal action of nanocomposites against the bacteria started with disruption of the bacterial membrane, subsequent cellular internalization of the nanoparticles, and inhibition of intracellular enzymatic activity. This novel antimicrobial material with good cytocompatibility promotes healing of infected wounds in diabetic rats, and has a promising future in the treatment of other infectious diseases.

  8. 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

  9. 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

  10. Occult bacterial lower urinary tract infections in cats-urinalysis and culture findings.

    Science.gov (United States)

    Litster, Annette; Moss, Susan; Platell, Joanne; Trott, Darren J

    2009-04-14

    Bacterial urinary tract infections (UTIs) can be detected in feline urine submitted for urinalysis and culture as part of the diagnostic workup for a variety of conditions. Our aim was to investigate urinalysis and culture findings in urine specimens from cats with no history of lower urinary tract signs. Study inclusion criteria required cystocentesis specimens from cats with no history of lower urinary tract signs, inappropriate urination, or previous UTI (including pyelonephritis). Of 132 specimens, 38 were culture positive and 94 were culture negative. Culture positive urine specimens were more likely to come from older female cats (p=0.03, p<0.001, respectively) and they had higher pH (p=0.001), erythrocyte (p=0.013) and leukocyte counts (p=0.003) than culture negative urine specimens. Gram-negative infected specimens (n=15) had lower urine specific gravity and higher leukocyte counts than Gram-positive infected specimens (n=21; p=0.0012, p=0.005, respectively) and culture negative specimens (p=0.003, p<0.0001, respectively). Urine protein:creatinine ratio was higher in Gram-negative infected urine than in culture negative urine (p=0.013). Enterococcus faecalis was the most commonly isolated bacteria (19 of a total of 44 isolates; 43.2%) and E. coli phylogenetic group B2 was the most common Gram-negative isolate (14 of a total of 44 isolates; 31.8%). We conclude that feline bacterial urinary tract infections can occur in cats without lower urinary tract signs, particularly older females and that they are associated with high urine erythrocyte and leukocyte counts.

  11. Evaluation of aztreonam and ampicillin vs. amikacin and ampicillin for treatment of neonatal bacterial infections.

    Science.gov (United States)

    Umaña, M A; Odio, C M; Castro, E; Salas, J L; McCracken, G H

    1990-03-01

    In a prospective randomized, open study we evaluated aztreonam (AZ) for treatment of neonatal bacterial infections. There were 147 patients enrolled in the study; 75 received AZ and ampicillin (AMP) and 72 amikacin (AM) and AMP (conventional therapy). Twenty-eight AZ/AMP-treated patients and 32 conventionally treated patients had bacteriologically documented infections caused by gram-negative enteric bacilli or Pseudomonas species. Treatment groups were comparable in age, clinical status, and type and severity of underlying disease at the time of enrollment. Bronchopneumonia and infections caused by Pseudomonas species occurred significantly more often in AM/AMP-treated patients compared with patients given AZ/AMP. Sepsis was documented in 83% of patients in each treatment group and Gram-negative enteric bacilli and Pseudomonas species were the principal pathogens. Median peak serum bactericidal titers against the etiologic agent were 1:64 for the AZ/AMP and 1:16 for AM/AMP-treated patients. Case fatality rates resulting from the primary infection were 7 and 22% (P = 0.011), superinfection occurred in 39% and 34% and treatment failure occurred in 7 and 28% (P = 0.036) of the AZ/AMP and AM/AMP-treated patients, respectively. No clinical adverse reactions were observed in either group. Based on these results aztreonam appears to be at least as effective as and possibly more effective than amikacin when used initially with ampicillin for empiric treatment of neonatal bacterial infections.

  12. Emerging treatment options for acute bacterial skin and skin structure infections: focus on intravenous delafloxacin

    Directory of Open Access Journals (Sweden)

    Righi E

    2018-04-01

    Full Text Available Elda Righi, Alessia Carnelutti, Antonio Vena, Matteo Bassetti Infectious Diseases Division, Santa Maria della Misericordia University Hospital, Udine, Italy Abstract: The increase in hospitalization due to acute bacterial skin and skin structure infections (ABSSSI caused by resistant pathogens supports the need for new treatment options. Antimicrobial options for ABSSSI that provide broad-spectrum coverage, including gram-negative pathogens and multidrug-resistant gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA, are limited. Delafloxacin is a novel fluoroquinolone available as intravenous and oral formulations and is characterized by an increased efficacy in acidic environments and activity on bacterial biofilm. Delafloxacin displays enhanced in vitro activity against MRSA, and enterococci, while maintaining efficacy against gram-negative pathogens and anaerobes. Delafloxacin has been studied for the treatment of ABSSSI and respiratory infections. Phase III studies have demonstrated noninferiority of delafloxacin compared to vancomycin, linezolid, tigecycline, and the combination of vancomycin plus aztreonam in the treatment of ABSSSI. Due to its favorable pharmacokinetic characteristics, the wide spectrum of action, and the potential for sequential therapy, delafloxacin represents a promising option in the empirical and targeted treatment of ABSSSI, both in hospital- and in community-based care. Keywords: bacterial skin and skin structure infections, multidrug-resistant bacteria, methicillin-resistant Staphylococcus aureus, delafloxacin

  13. 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.

  14. Resistencia a antibióticos de bacilos GRAM negativos aislados en unidades de cuidados intensivos: Análisis comparativo de dos periódos (1998-2001 Bacterial resistance to antibiotics in gram negative isolates from intensive care units: Comparative analysis between two periods (1998-2001

    Directory of Open Access Journals (Sweden)

    C. H. Rodriguez

    2003-01-01

    Full Text Available Se comparó la incidencia relativa de las diferentes especies de bacilos gram-negativos y la resistencia a varios antibacterianos, en dos muestras de aislamientos clínicos correspondientes a cinco meses del año 1998 y del mismo período del año 2001, con el objetivo de conocer la evolución de ambos, frecuencia de cada especie como agente etiológico, y resistencia a antimicrobianos. Para ello se analizaron en cada período 100 aislamientos de bacilos gram-negativos obtenidos de muestras clínicas de pacientes internados en salas de cuidados intensivos del Hospital de Clínicas José de San Martín. Se determinó la especie bacteriana y la concentración inhibitoria mínima de cada antibiótico. Acinetobacter spp. fue el microorganismo más aislado en ambos períodos. El porcentaje de aislamientos resistentes a imipenem fue del 60%, mientras que a ciprofloxacina y cefalosporinas de tercera generación fue superior al 80%. En Klebsiella pneumoniae el porcentaje de aislamientos resistentes a cefalosporinas de tercera generación disminuyó del 71.4 al 30% (pThe incidence and drug susceptibility of gram-negative isolates from clinical samples of patients from different intensive care units at the Hospital de Clinicas José de San Martín were analysed. Two hundred isolates during the same five months period, in two different years (1998 and 2001 were obtained and evaluated. Acinetobacter spp., was the most frequently isolated microorganism. Resistance to imipenem was observed in 60% of these isolations while resistance to 3rd generation cephalosporin and ciprofloxacin was observed in more than 80%. Klebsiella pneumoniae was not resistant to imipenem, the resistance to 3rd and 4rth generation cephalosporins decreased from 71.4 to 30% of isolates (p<0.05, while ciprofloxacin resistance increased from 5 to 20% (p<0.05. An increasing resistance to imipenem in Pseudomonas aeruginosa was noted, from 15.4 to 68% (p<0.05%; to ciprofloxacin, from 31.4 to

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

    Directory of Open Access Journals (Sweden)

    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

  16. 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.

  17. 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.

  18. 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.

  19. Optimized localization of bacterial infections with technetium-99m labelled human immunoglobulin after protein charge selection

    International Nuclear Information System (INIS)

    Welling, M.; Feitsma, H.I.J.; Calame, W.; Ensing, G.J.; Goedemans, W.; Pauwels, E.K.J.

    1994-01-01

    To improve the scintigraphic detection of bacterial infections a protein charge-purified fraction of polyclonal human immunoglobulin was applied as a radiopharmaceutical. This purification was achieved by attaching the immunoglobulin to an anion-exchanger column and by obtaining the column-bound fraction with buffer. The binding to bacteria in vitro and the target to non-target ratios of an experimental thigh infection with Staphylococcus aureus or Klebsiella pneumoniae in mice were evaluated to compare the purified and the unpurified immunoglobulin. The percentage of binding to all gram-positive and gram-negative bacteria used in this study was significantly (P 99m Tc-labelled protein charge-purified polyclonal human immunoglobulin was administered intravenously. At all time intervals the target (infected thighs) to non-target (non-infected thighs) ratios for both infections were significantly higher (P 99m Tc-labelled protein charge-purified immunoglobulin localizes both a gram-positive and a gram-negative thigh infection more intensely and faster than 99m Tc-labelled unpurified immunoglobulin. (orig.)

  20. Adjunctive aerosolized colistin for multi-drug resistant gram-negative pneumonia in the critically ill: a retrospective study

    OpenAIRE

    Doshi, Neha M; Cook, Charles H; Mount, Kari L; Stawicki, Stanislaw P; Frazee, Erin N; Personett, Heather A; Schramm, Garrett E; Arnold, Heather M; Murphy, Claire V

    2013-01-01

    Background The incidence of multi-drug resistant (MDR) gram-negative (GN) organisms including Pseudomonas and Acinetobacter spp has increased in the last decade, prompting re-evaluation of colistin for the management of these infections. Aerosolized colistin as an adjunct to intravenous therapy is a current option for the management of MDR-GN pneumonia, although data supporting this practice is limited. This study evaluates the efficacy of adjunctive aerosolized colistin in combination with i...

  1. Microbiological and kinetic detection of gram negative bacilli ...

    African Journals Online (AJOL)

    Conclusion: This study showed that bacterial resistances by extended- spectrum β-lactamases are a reality in University Hospital center YalgadoOuedraogo. It calls about antibiotics prescription and hospital hygiene in order to reduce emergence and propagation of new resisting bacterial. Keywords: microbial and kinetic ...

  2. [Bacterial culture and drug sensitivity analysis of upper urinary tract calculi complicating with infection].

    Science.gov (United States)

    Wang, Shu; Shi, Yong-kang; Huang, Xiao-bo; Ma, Kai; Xu, Qing-quan; Xiong, Lin-lin; Li, Jian-xing; Wang, Xia-feng

    2014-10-18

    To investigate the bacteriology and drug sensitivity of upper urinary tract calculi patients, and to provide information for choosing suitable antibiotics. In the study, 21 patients who suffered from lithiasis in upper urinary tract and required an emergency drainage for acute obstruction and infection were the "acute group"; 64 patients with calculi in upper urinary tract and accompanied with no infectious symptoms were the "common group". The bacteriology and drug sensitivity of the two groups were investigated. Gram-negative bacteria infected the most common of upper urinary tract calculi patients with infection, accounting for 71.4% in the acute group and 65.7% in the common group, among which Escherichia coli were the predominant ones (35.7% in the acute group and 32.9% in the common group). No difference was found between these two groups in bacterial distribution (P>0.05). Although the average drug resistance rate of Gram-negative bacteria in the acute group was higher than that in the common group, it revealed no significant difference (P>0.05). The drug resistance rate to semisynthetic penicillin, cefuroxime and ceftriaxone were more than 50%, 60%, and 50%, respectively. Quinolones, such as ciprofloxacin and levofloxacin, got a 45% drug resistance. Aminoglycoside, carbapenema were sensitive to Gram-negative bacteria. Cefoperazone/sulbactam and piperacillin/tazobactam were more effective than ceftriaxone and piperacillin, respectively. There was no significant difference between upper urinary tract calculi patients with acute infection and common infection in bacteriology and drug sensitivity. Semisynthetic penicillin, the second generation of cephalosporin and quinolone were no longer the good choices of empirical use. Antibiotics combined with β-lactamase inhibitors would be an ideal empirical therapeutic choice.

  3. Prevalence and bacterial susceptibility of hospital acquired urinary tract infection

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    Dias Neto José Anastácio

    2003-01-01

    Full Text Available PURPOSE: Urinary tract infection is the most common nosocomially acquired infection. It is important to know the etiology and antibiotic susceptibility infectious agents to guide the initial empirical treatment. OBJECTIVE: To determine the prevalence of bacterial strains and their antibiotic susceptibility in nosocomially acquired urinary tract infection in a university hospital between January and June 2003. METHODS: We analyzed the data of 188 patients with positive urine culture (= 10(5 colony-forming units/mL following a period of 48 hours after admission. RESULTS: Half of patients were male. Mean age was 50.26 ± 22.7 (SD, range 3 months to 88 years. Gram-negative bacteria were the agent in approximately 80% of cases. The most common pathogens were E. coli (26%, Klebsiella sp. (15%, P. aeruginosa (15% and Enterococcus sp. (11%. The overall bacteria susceptibility showed that the pathogens were more sensible to imipenem (83%, second or third generation cephalosporin and aminoglycosides; and were highly resistant to ampicillin (27% and cefalothin (30%. It is important to note the low susceptibility to ciprofloxacin (42% and norfloxacin (43%. CONCLUSION: This study suggests that if one can not wait the results of urine culture, the best choices to begin empiric treatment are imipenem, second or third generation cephalosporin and aminoglycosides. Cefalothin and ampicillin are quite ineffective to treat these infections.

  4. New transposon tools tailored for metabolic engineering of Gram-negative microbial cell factories

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    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

  5. 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

  6. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  8. Phenotypic and Genotypic Detection of Metallo-beta-lactamases among Imipenem-Resistant Gram Negative Isolates

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    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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. Bacterial Skin Infections

    Science.gov (United States)

    ... other immune disorders, or hepatitis People who are undergoing chemotherapy or treatment with other drugs that suppress the immune system Skin that is inflamed or damaged by sunburn, scratching, or other trauma is more likely to become infected. In fact, ...

  15. 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

  16. Gram-negative bacteraemia; a multi-centre prospective evaluation of empiric antibiotic therapy and outcome in English acute hospitals.

    Science.gov (United States)

    Fitzpatrick, J M; Biswas, J S; Edgeworth, J D; Islam, J; Jenkins, N; Judge, R; Lavery, A J; Melzer, M; Morris-Jones, S; Nsutebu, E F; Peters, J; Pillay, D G; Pink, F; Price, J R; Scarborough, M; Thwaites, G E; Tilley, R; Walker, A S; Llewelyn, M J

    2016-03-01

    Increasing antibiotic resistance makes choosing antibiotics for suspected Gram-negative infection challenging. This study set out to identify key determinants of mortality among patients with Gram-negative bacteraemia, focusing particularly on the importance of appropriate empiric antibiotic treatment. We conducted a prospective observational study of 679 unselected adults with Gram-negative bacteraemia at ten acute english hospitals between October 2013 and March 2014. Appropriate empiric antibiotic treatment was defined as intravenous treatment on the day of blood culture collection with an antibiotic to which the cultured organism was sensitive in vitro. Mortality analyses were adjusted for patient demographics, co-morbidities and illness severity. The majority of bacteraemias were community-onset (70%); most were caused by Escherichia coli (65%), Klebsiella spp. (15%) or Pseudomonas spp. (7%). Main foci of infection were urinary tract (51%), abdomen/biliary tract (20%) and lower respiratory tract (14%). The main antibiotics used were co-amoxiclav (32%) and piperacillin-tazobactam (30%) with 34% receiving combination therapy (predominantly aminoglycosides). Empiric treatment was inappropriate in 34%. All-cause mortality was 8% at 7 days and 15% at 30 days. Independent predictors of mortality (p antibiotic therapy was not associated with mortality at either time-point (adjusted OR 0.82; 95% CI 0.35-1.94 and adjusted OR 0.92; 95% CI 0.50-1.66, respectively). Although our study does not exclude an impact of empiric antibiotic choice on survival in Gram-negative bacteraemia, outcome is determined primarily by patient and disease factors. Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  17. 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.

  18. 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...

  19. Critical appraisal of ceftaroline in the management of community-acquired bacterial pneumonia and skin infections

    Directory of Open Access Journals (Sweden)

    Goodman JJ

    2012-03-01

    Full Text Available Julian J Goodman, Stanley I MartinDivision of Infectious Diseases, The Ohio State University, Columbus, OH, USAAbstract: Ceftaroline is a novel broad-spectrum cephalosporin ß-lactam antibiotic with activity against methicillin-resistant Staphylococcus aureus (MRSA as well as multidrug-resistant Streptococcus pneumoniae among other routine Gram positive and Gram negative organisms. It has been approved by the US Food and Drug Administration for treatment of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections (ABSSSIs. Ceftaroline is approved for treatment of ABSSSI due to MRSA, however currently there are no data for pneumonia due to MRSA in humans. Herein we review the major clinical trials as well as ceftaroline microbiology, pharmacokinetics, and safety, followed by a look at further directions for investigation of this new agent.Keywords: ceftaroline, pneumonia, skin infection

  20. 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...

  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. 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....

  3. 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.

  4. Pathogenic E.coli and other pathogenic gram negative enteric ...

    African Journals Online (AJOL)

    Background: Diarrhoea remains a major public health problem among children and adults in developing nations such as Kenya. The risk of infection is higher in children due to their developing immunity, relatively poor hygiene and habits especially those living in informal settlements where water supply and sanitation are ...

  5. 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 ...

  6. 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.

  7. (PCR) in the diagnosis of bacterial infections

    African Journals Online (AJOL)

    ... bacterial infections that can be diagnosed using the technique which include among others; Tuberculosis (TB), whooping cough, brain abscesses and spinal infection, otitis media with effusion, Mycoplasmal pneumonia, endophthalmitis and bacterial meningitis. Keywords: Polymerase chain reaction, Diagnosis, Bacteria, ...

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

    Directory of Open Access Journals (Sweden)

    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.

  9. Ionome changes in Xylella fastidiosa-infected Nicotiana tabacum correlate with virulence and discriminate between subspecies of bacterial isolates.

    Science.gov (United States)

    Oliver, J E; Sefick, S A; Parker, J K; Arnold, T; Cobine, P A; De La Fuente, L

    2014-10-01

    Characterization of ionomes has been used to uncover the basis of nutrient utilization and environmental adaptation of plants. Here, ionomic profiles were used to understand the phenotypic response of a plant to infection by genetically diverse isolates of Xylella fastidiosa, a gram-negative, xylem-limited bacterial plant pathogen. In this study, X. fastidiosa isolates were used to infect a common model host (Nicotiana tabacum 'SR1'), and leaf and sap concentrations of eleven elements together with plant colonization and symptoms were assessed. Multivariate statistical analysis revealed that changes in the ionome were significantly correlated with symptom severity and bacterial populations in host petioles. Moreover, plant ionome modification by infection could be used to differentiate the X. fastidiosa subspecies with which the plant was infected. This report establishes host ionome modification as a phenotypic response to infection.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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.

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

    Science.gov (United States)

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

    Directory of Open Access Journals (Sweden)

    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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Bacterial biofilm and associated infections

    Directory of Open Access Journals (Sweden)

    Muhsin Jamal

    2018-01-01

    Full Text Available Microscopic entities, microorganisms that drastically affect human health need to be thoroughly investigated. A biofilm is an architectural colony of microorganisms, within a matrix of extracellular polymeric substance that they produce. Biofilm contains microbial cells adherent to one-another and to a static surface (living or non-living. Bacterial biofilms are usually pathogenic in nature and can cause nosocomial infections. The National Institutes of Health (NIH revealed that among all microbial and chronic infections, 65% and 80%, respectively, are associated with biofilm formation. The process of biofilm formation consists of many steps, starting with attachment to a living or non-living surface that will lead to formation of micro-colony, giving rise to three-dimensional structures and ending up, after maturation, with detachment. During formation of biofilm several species of bacteria communicate with one another, employing quorum sensing. In general, bacterial biofilms show resistance against human immune system, as well as against antibiotics. Health related concerns speak loud due to the biofilm potential to cause diseases, utilizing both device-related and non-device-related infections. In summary, the understanding of bacterial biofilm is important to manage and/or to eradicate biofilm-related diseases. The current review is, therefore, an effort to encompass the current concepts in biofilm formation and its implications in human health and disease.

  5. Screening of the novel colicinogenic gram-negative rods against pathogenic Escherichia coli O157:H7

    Directory of Open Access Journals (Sweden)

    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.

  6. 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.

  7. Protection against Helicobacter pylori and other bacterial infections by garlic.

    Science.gov (United States)

    Sivam, G P

    2001-03-01

    Louis Pasteur was the first to describe the antibacterial effect of onion and garlic juices. Historically, garlic has been used worldwide to fight bacterial infections. Allium vegetables, particularly garlic (Allium sativum L.) exhibit a broad antibiotic spectrum against both gram-positive and gram-negative bacteria. Noteworthy results published include the following: 1) raw juice of garlic was found to be effective against many common pathogenic bacteria-intestinal bacteria, which are responsible for diarrhea in humans and animals; 2) garlic is effective even against those strains that have become resistant to antibiotics; 3) the combination of garlic with antibiotics leads to partial or total synergism; 4) complete lack of resistance has been observed repeatedly; 5) even toxin production by microorganisms is prevented by garlic. Helicobacter pylori (H. pylori) is a bacterium implicated in the etiology of stomach cancer and ulcers. The incidence of stomach cancer is lower in populations with a high intake of allium vegetables. We have demonstrated in vitro that H. pylori is susceptible to garlic extract at a fairly moderate concentration. Even some antibiotic-resistant H. pylori strains are susceptible to garlic. Clinical trials are necessary to explore the possibility of using garlic as a low-cost remedy for eradicating H. pylori.

  8. 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.

  9. Infection and colonization by Gram-negative bacilli in neonates hospitalized in High Risk Nursery at Uberlandia Federal University Hospital: etiology, resistant phenotypes and risk factors Infecção e colonização por bacilos Gram-negativos em neonatos internados em Berçário de Alto Risco do Hospital da Universidade Federal de Uberlândia: etiologia, fenótipos de resistência e fatores de risco

    Directory of Open Access Journals (Sweden)

    Renata Cristina Cezário

    2004-09-01

    Full Text Available The aims of this study were to determine endemic and epidemic infection due to Gram-negative bacilli, risk factors associated with colonization and infection by these organisms and the resistance phenotypes (ESBL, AmpC in neonates admitted in a High Risk Nursery. The study was conducted during a 21 month period and included: a prospective study to evaluate the neonates with hospital infection and the use of third-generation cephalosporins; a case-control study to determine the risk factors associated with colonization/infection. Rectal and oropharynx cultures were also performed in four opportunities (September and November 2001, February and August 2002. The isolates for which the resistance of ceftazidime was 2 mg/mL were suspected of producing ESBL or AmpC b-lactamases. The incidence of infection by Gram-negative bacilli was 2.4% (89/3.708 neonates, and sepsis (35.9% and conjunctivitis (31.4% were the most common infections. The endemic infections were more prevalent (73.9% and usually associated with Enterobacteriaceae (95.5%, being these organisms also related to colonization, corresponding mainly to isolates of Enterobacter spp. and Klebsiella spp. Two outbreaks of Pseudomonas aeruginosa (n=10 and Acinetobacter baumannii (n=11 were identified during the survey. Univariate analysis showed that risk factors for Gram-negative bacilli infection considered significant included: the length of stay before infection/colonization, exposure to antimicrobial agents, mechanical ventilation, central venous catheters, parenteral nutrition and surgery. The majority of resistance to ceftazidime among Enterobacteriaceae isolates (80.9% was from ESBL phenotype. Administration of third-generation cephalosporins (ceftriaxone led to the emergence of these multiresistant Gram-negative bacilli in the neonatal unit.Os objetivos deste estudo foram determinar infecções endêmicas e epidêmicas por bacilos Gram-negativos, fatores de risco associados a coloniza

  10. Detection of -Lactamases in nosocomial gram negative clinical isolates

    Directory of Open Access Journals (Sweden)

    Rodrigues C

    2004-01-01

    Full Text Available -lactamases represent the most common mechanism of -lactam resistance. Extended spectrum -lactamases (ESBLs represent a major group of -lactamses currently being identified worldwide in large numbers along with inducible AmpC -lactamases and derepressed mutants. The present study was done to detect -lactamase production in clinical isolates by rearranging routine discs used in reporting susceptibility to specifically assess ESBLs, AmpC -lactamases (both inducible and hyperproducers i.e., derepressed mutants. A total of 286 clinical isolates were studied using a novel predictor disc approximation method to detect the above mechanisms of resistance with careful use and placement of antimicrobial discs. Of the 286 isolates, 151(53% were ESBL producers of which 131(46% were also derepressed mutants while remaining 20(7% were plain ESBL producers. Forty (14% were plain derepressed mutants. Inducible AmpC -lactamase production was detected in 19(7% of the isolates. The commonest ESBL producers were E.coli and K. pneumoniae. The high incidence of -lactamase production due to multiple mechanisms in clinical isolates is alarming and urgent action needs to be taken from both a therapeutic and infection control perspective.

  11. Optimized localization of bacterial infections with technetium-99m labelled human immunoglobulin after protein charge selection

    Energy Technology Data Exchange (ETDEWEB)

    Welling, M. (Dept. of Diagnostic Radiology and Nuclear Medicine, University Hospital, Leiden (Netherlands)); Feitsma, H.I.J. (Dept. of Diagnostic Radiology and Nuclear Medicine, University Hospital, Leiden (Netherlands)); Calame, W. (Dept. of Diagnostic Radiology and Nuclear Medicine, University Hospital, Leiden (Netherlands)); Ensing, G.J. (Mallinckrodt Medical, Petten (Netherlands)); Goedemans, W. (Mallinckrodt Medical, Petten (Netherlands)); Pauwels, E.K.J. (Dept. of Diagnostic Radiology and Nuclear Medicine, University Hospital, Leiden (Netherlands))

    1994-10-01

    To improve the scintigraphic detection of bacterial infections a protein charge-purified fraction of polyclonal human immunoglobulin was applied as a radiopharmaceutical. This purification was achieved by attaching the immunoglobulin to an anion-exchanger column and by obtaining the column-bound fraction with buffer. The binding to bacteria in vitro and the target to non-target ratios of an experimental thigh infection with Staphylococcus aureus or Klebsiella pneumoniae in mice were evaluated to compare the purified and the unpurified immunoglobulin. The percentage of binding to all gram-positive and gram-negative bacteria used in this study was significantly (P<0.03) higher for the purified than for the unpurified immunoglobulin. For the in vivo study, mice were infected in the thigh muscle with Staph. aureus or K. pneumoniae. After 18 h 0.1 mg of technetium-99m labelled polyclonal immunoglobulin or [sup 99m]Tc-labelled protein charge-purified polyclonal human immunoglobulin was administered intravenously. At all time intervals the target (infected thighs) to non-target (non-infected thighs) ratios for both infections were significantly higher (P<0.03) for protein charge-purified polyclonal immunoglobulin than for unpurified polyclonal human immunoglobulin. Already within 1 h the infected tissues could be detected by the purified immunoglobulin. It is concluded that [sup 99m]Tc-labelled protein charge-purified immunoglobulin localizes both a gram-positive and a gram-negative thigh infection more intensely and faster than [sup 99m]Tc-labelled unpurified immunoglobulin. (orig.)

  12. Antioxidant activity via DPPH, gram-positive and gram-negative antimicrobial potential in edible mushrooms.

    Science.gov (United States)

    Ahmad, Nisar; Mahmood, Fazal; Khalil, Shahid Akbar; Zamir, Roshan; Fazal, Hina; Abbasi, Bilal Haider

    2014-10-01

    Edible mushrooms (EMs) are nutritionally rich source of proteins and essential amino acids. In the present study, the antioxidant activity via 1,1-diphenyl-2-picrylhydrazyl (DPPH) and antimicrobial potential in EMs (Pleurotus ostreatus, Morchella esculenta, P. ostreatus (Black), P. ostreatus (Yellow) and Pleurotus sajor-caju) were investigated. The DPPH radical scavenging activity revealed that the significantly higher activity (66.47%) was observed in Morchella esculenta at a maximum concentration. Similarly, the dose-dependent concentrations (200, 400, 600, 800 and 1000 µg) were also used for other four EMs. Pleurotus ostreatus exhibited 36.13% activity, P. ostreatus (Black (B)) exhibited 30.64%, P. ostreatus (Yellow (Y)) exhibited 40.75% and Pleurotus sajor-caju exhibited 47.39% activity at higher concentrations. Furthermore, the antimicrobial potential were investigated for its toxicity against gram-negative bacterial strains (Escherichia coli, Pseudomonas aeroginosa, Salmonella typhi, Klebsiella pneumonia, Erwinia carotovora and Agrobacterium tumifaciens), gram-positive bacterial strains (Bacillus subtilis, Bacillus atrophaeus and Staphylococcus aureus) and a fungal strain (Candida albicans) in comparison with standard antibiotics. Antimicrobial screening revealed that the ethanol extract of P. ostreatus was active against all microorganism tested except E. coli. Maximum zone of inhibition (13 mm) was observed against fungus and A. tumifaciens. P. sajor-caju showed best activities (12.5 mm) against B. subtilis, B. atrophaeus and K. pneumonia. P. ostreatus (Y) showed best activities against P. aeroginosa (21.83 mm), B. atrophaeus (20 mm) and C. albicans (21 mm). P. ostreatus (B) exhibited best activities against C. albicans (16 mm) and slightly lower activities against all other microbes except S. typhi. M. esculenta possess maximum activities in terms of inhibition zone against all microorganisms tested except S. typhi. © The Author(s) 2012.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. [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 is rare in Algeria. Some Enterobacteriaceae producing OXA-48 or VIM-19 have been reported; so far, only VIM-2 has been identified in P. aeruginosa. However, the situation regarding the strains of Acinetobacter baumannii resistant to carbapenemases seems to be more disturbing. The carbapenemase OXA-23 is the most common and seems to be endemic in the north. The carbapenemase NDM-1 has also been identified. Resistance to aminoglycosides is marked by the identification armA gene associated with blaCTX-M genes in strains of Salmonella sp. Several other resistance genes have been identified sporadically in strains of Enterobacteriaceae, P. aeruginosa and A. baumannii. Resistance genes to fluoroquinolones are more recent identification in Algeria. The most common are the Qnr determinants followed by the bifunctional enzyme AAC[6']-Ib-cr. Resistance to sulfonamides and trimethoprim was also reported in Enterobacteriaceae strains in the west of the country. Copyright © 2014. Published by Elsevier SAS.

  18. 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.

  19. 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.

  20. 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.

  1. Pattern of Bacterial Pathogens and Their Susceptibility Isolated from Surgical Site Infections at Selected Referral Hospitals, Addis Ababa, Ethiopia

    Directory of Open Access Journals (Sweden)

    Walelign Dessie

    2016-01-01

    Full Text Available Background. The emergence of multidrug resistant bacterial pathogens in hospitals is becoming a challenge for surgeons to treat hospital acquired infections. Objective. To determine bacterial pathogens and drug susceptibility isolated from surgical site infections at St. Paul Specialized Hospital Millennium Medical College and Yekatit 12 Referral Hospital Medical College, Addis Ababa, Ethiopia. Methods. A cross-sectional study was conducted between October 2013 and March 2014 on 107 surgical site infected patients. Wound specimens were collected using sterile cotton swab and processed as per standard operative procedures in appropriate culture media; and susceptibility testing was done using Kirby-Bauer disc diffusion technique. The data were analyzed by using SPSS version 20. Result. From a total of 107 swabs collected, 90 (84.1% were culture positive and 104 organisms were isolated. E. coli (24 (23.1% was the most common organism isolated followed by multidrug resistant Acinetobacter species (23 (22.1%. More than 58 (75% of the Gram negative isolates showed multiple antibiotic resistance (resistance ≥ 5 drugs. Pan-antibiotic resistance was noted among 8 (34.8% Acinetobacter species and 3 (12.5% E. coli. This calls for abstinence from antibiotic abuse. Conclusion. Gram negative bacteria were the most important isolates accounting for 76 (73.1%. Ampicillin, amoxicillin, penicillin, cephazoline, and tetracycline showed resistance while gentamicin and ciprofloxacin were relatively effective antimicrobials.

  2. 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.

  3. 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...

  4. 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.

  5. 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.

  6. 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.

  7. Isolation and in vitro evaluation of bacteriophages against MDR-bacterial isolates from septic wound infections.

    Science.gov (United States)

    Pallavali, Roja Rani; Degati, Vijaya Lakshmi; Lomada, Dakshayani; Reddy, Madhava C; Durbaka, Vijaya Raghava Prasad

    2017-01-01

    Multi-drug resistance has become a major problem for the treatment of pathogenic bacterial infections. The use of bacteriophages is an attractive approach to overcome the problem of drug resistance in several pathogens that cause fatal diseases. Our study aimed to isolate multi drug resistant bacteria from patients with septic wounds and then isolate and apply bacteriophages in vitro as alternative therapeutic agents. Pus samples were aseptically collected from Rajiv Gandhi Institute of Medical Science (RIMS), Kadapa, A.P., and samples were analyzed by gram staining, evaluating morphological characteristics, and biochemical methods. MDR-bacterial strains were collected using the Kirby-Bauer disk diffusion method against a variety of antibiotics. Bacteriophages were collected and tested in vitro for lytic activity against MDR-bacterial isolates. Analysis of the pus swab samples revealed that the most of the isolates detected had Pseudomonas aeruginosa as the predominant bacterium, followed by Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. Our results suggested that gram-negative bacteria were more predominant than gram-positive bacteria in septic wounds; most of these isolates were resistant to ampicillin, amoxicillin, penicillin, vancomycin and tetracycline. All the gram-positive isolates (100%) were multi-drug resistant, whereas 86% of the gram-negative isolates had a drug resistant nature. Further bacteriophages isolated from sewage demonstrated perfect lytic activity against the multi-drug resistant bacteria causing septic wounds. In vitro analysis of the isolated bacteriophages demonstrated perfect lysis against the corresponding MDR-bacteria, and these isolated phages may be promising as a first choice for prophylaxis against wound sepsis, Moreover, phage therapy does not enhance multi-drug resistance in bacteria and could work simultaneously on a wide variety of MDR-bacteria when used in a bacteriophage cocktail. Hence, our results suggest

  8. Development of Methionyl-tRNA Synthetase Inhibitors as Antibiotics for Gram-Positive Bacterial Infections.

    Science.gov (United States)

    Faghih, Omeed; Zhang, Zhongsheng; Ranade, Ranae M; Gillespie, J Robert; Creason, Sharon A; Huang, Wenlin; Shibata, Sayaka; Barros-Álvarez, Ximena; Verlinde, Christophe L M J; Hol, Wim G J; Fan, Erkang; Buckner, Frederick S

    2017-11-01

    Antibiotic-resistant bacteria are widespread and pose a growing threat to human health. New antibiotics acting by novel mechanisms of action are needed to address this challenge. The bacterial methionyl-tRNA synthetase (MetRS) enzyme is essential for protein synthesis, and the type found in Gram-positive bacteria is substantially different from its counterpart found in the mammalian cytoplasm. Both previously published and new selective inhibitors were shown to be highly active against Gram-positive bacteria with MICs of ≤1.3 μg/ml against Staphylococcus , Enterococcus , and Streptococcus strains. Incorporation of radioactive precursors demonstrated that the mechanism of activity was due to the inhibition of protein synthesis. Little activity against Gram-negative bacteria was observed, consistent with the fact that Gram-negative bacterial species contain a different type of MetRS enzyme. The ratio of the MIC to the minimum bactericidal concentration (MBC) was consistent with a bacteriostatic mechanism. The level of protein binding of the compounds was high (>95%), and this translated to a substantial increase in MICs when the compounds were tested in the presence of serum. Despite this, the compounds were very active when they were tested in a Staphylococcus aureus murine thigh infection model. Compounds 1717 and 2144, given by oral gavage, resulted in 3- to 4-log decreases in the bacterial load compared to that in vehicle-treated mice, which was comparable to the results observed with the comparator drugs, vancomycin and linezolid. In summary, the research describes MetRS inhibitors with oral bioavailability that represent a class of compounds acting by a novel mechanism with excellent potential for clinical development. Copyright © 2017 American Society for Microbiology.

  9. Isolation and in vitro evaluation of bacteriophages against MDR-bacterial isolates from septic wound infections.

    Directory of Open Access Journals (Sweden)

    Roja Rani Pallavali

    Full Text Available Multi-drug resistance has become a major problem for the treatment of pathogenic bacterial infections. The use of bacteriophages is an attractive approach to overcome the problem of drug resistance in several pathogens that cause fatal diseases. Our study aimed to isolate multi drug resistant bacteria from patients with septic wounds and then isolate and apply bacteriophages in vitro as alternative therapeutic agents. Pus samples were aseptically collected from Rajiv Gandhi Institute of Medical Science (RIMS, Kadapa, A.P., and samples were analyzed by gram staining, evaluating morphological characteristics, and biochemical methods. MDR-bacterial strains were collected using the Kirby-Bauer disk diffusion method against a variety of antibiotics. Bacteriophages were collected and tested in vitro for lytic activity against MDR-bacterial isolates. Analysis of the pus swab samples revealed that the most of the isolates detected had Pseudomonas aeruginosa as the predominant bacterium, followed by Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. Our results suggested that gram-negative bacteria were more predominant than gram-positive bacteria in septic wounds; most of these isolates were resistant to ampicillin, amoxicillin, penicillin, vancomycin and tetracycline. All the gram-positive isolates (100% were multi-drug resistant, whereas 86% of the gram-negative isolates had a drug resistant nature. Further bacteriophages isolated from sewage demonstrated perfect lytic activity against the multi-drug resistant bacteria causing septic wounds. In vitro analysis of the isolated bacteriophages demonstrated perfect lysis against the corresponding MDR-bacteria, and these isolated phages may be promising as a first choice for prophylaxis against wound sepsis, Moreover, phage therapy does not enhance multi-drug resistance in bacteria and could work simultaneously on a wide variety of MDR-bacteria when used in a bacteriophage cocktail. Hence

  10. Tobacco use increases susceptibility to bacterial infection

    Directory of Open Access Journals (Sweden)

    Demuth Donald R

    2008-12-01

    Full Text Available Abstract Active smokers and those exposed to secondhand smoke are at increased risk of bacterial infection. Tobacco smoke exposure increases susceptibility to respiratory tract infections, including tuberculosis, pneumonia and Legionnaires disease; bacterial vaginosis and sexually transmitted diseases, such as chlamydia and gonorrhoea; Helicobacter pylori infection; periodontitis; meningitis; otitis media; and post-surgical and nosocomial infections. Tobacco smoke compromises the anti-bacterial function of leukocytes, including neutrophils, monocytes, T cells and B cells, providing a mechanistic explanation for increased infection risk. Further epidemiological, clinical and mechanistic research into this important area is warranted.

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. Ceftolozane/tazobactam: a novel cephalosporin/β-lactamase inhibitor combination with activity against multidrug-resistant gram-negative bacilli.

    Science.gov (United States)

    Zhanel, George G; Chung, Phillip; Adam, Heather; Zelenitsky, Sheryl; Denisuik, Andrew; Schweizer, Frank; Lagacé-Wiens, Philippe R S; Rubinstein, Ethan; Gin, Alfred S; Walkty, Andrew; Hoban, Daryl J; Lynch, Joseph P; Karlowsky, James A

    2014-01-01

    Ceftolozane is a novel cephalosporin currently being developed with the β-lactamase inhibitor tazobactam for the treatment of complicated urinary tract infections (cUTIs), complicated intra-abdominal infections (cIAIs), and ventilator-associated bacterial pneumonia (VABP). The chemical structure of ceftolozane is similar to that of ceftazidime, with the exception of a modified side-chain at the 3-position of the cephem nucleus, which confers potent antipseudomonal activity. As a β-lactam, its mechanism of action is the inhibition of penicillin-binding proteins (PBPs). Ceftolozane displays increased activity against Gram-negative bacilli, including those that harbor classical β-lactamases (e.g., TEM-1 and SHV-1), but, similar to other oxyimino-cephalosporins such as ceftazidime and ceftriaxone, it is compromised by extended-spectrum β-lactamases (ESBLs) and carbapenemases. The addition of tazobactam extends the activity of ceftolozane to include most ESBL producers as well as some anaerobic species. Ceftolozane is distinguished from other cephalosporins by its potent activity versus Pseudomonas aeruginosa, including various drug-resistant phenotypes such as carbapenem, piperacillin/tazobactam, and ceftazidime-resistant isolates, as well as those strains that are multidrug-resistant (MDR). Its antipseudomonal activity is attributed to its ability to evade the multitude of resistance mechanisms employed by P. aeruginosa, including efflux pumps, reduced uptake through porins and modification of PBPs. Ceftolozane demonstrates linear pharmacokinetics unaffected by the coadministration of tazobactam; specifically, it follows a two-compartmental model with linear elimination. Following single doses, ranging from 250 to 2,000 mg, over a 1-h intravenous infusion, ceftolozane displays a mean plasma half-life of 2.3 h (range 1.9-2.6 h), a steady-state volume of distribution that ranges from 13.1 to 17.6 L, and a mean clearance of 102.4 mL/min. It demonstrates low

  19. 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.

  20. 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

  1. Detecting Nosocomial Intrinsic Infections through Relating Bacterial ...

    African Journals Online (AJOL)

    Sierra Leone Journal of Biomedical Research ... Surgical procedures often lead to both intrinsic and extrinsic infections. ... This study demonstrated surgical procedures as precursory to intrinsic infections and that bacterial pathogens found on wounds and endogenous indicators of surgery are links to intrinsic infection.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. 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

  10. Innate immune system favors emergency monopoiesis at the expense of DC-differentiation to control systemic bacterial infection in mice.

    Science.gov (United States)

    Pasquevich, Karina A; Bieber, Kristin; Günter, Manina; Grauer, Matthias; Pötz, Oliver; Schleicher, Ulrike; Biedermann, Tilo; Beer-Hammer, Sandra; Bühring, Hans-Jörg; Rammensee, Hans-Georg; Zender, Lars; Autenrieth, Ingo B; Lengerke, Claudia; Autenrieth, Stella E

    2015-10-01

    DCs are professional APCs playing a crucial role in the initiation of T-cell responses to combat infection. However, systemic bacterial infection with various pathogens leads to DC-depletion in humans and mice. The mechanisms of pathogen-induced DC-depletion remain poorly understood. Previously, we showed that mice infected with Yersinia enterocolitica (Ye) had impaired de novo DC-development, one reason for DC-depletion. Here, we extend these studies to gain insight into the molecular mechanisms of DC-depletion and the impact of different bacteria on DC-development. We show that the number of bone marrow (BM) hematopoietic progenitors committed to the DC lineage is reduced following systemic infection with different Gram-positive and Gram-negative bacteria. This is associated with a TLR4- and IFN-γ-signaling dependent increase of committed monocyte progenitors in the BM and mature monocytes in the spleen upon Ye-infection. Adoptive transfer experiments revealed that infection-induced monopoiesis occurs at the expense of DC-development. Our data provide evidence for a general response of hematopoietic progenitors upon systemic bacterial infections to enhance monocyte production, thereby increasing the availability of innate immune cells for pathogen control, whereas impaired DC-development leads to DC-depletion, possibly driving transient immunosuppression in bacterial sepsis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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

  12. 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

  13. Fusaric acid and analogues as Gram-negative bacterial quorum sensing inhibitors.

    Science.gov (United States)

    Tung, Truong Thanh; Jakobsen, Tim Holm; Dao, Trong Tuan; Fuglsang, Anja Thoe; Givskov, Michael; Christensen, Søren Brøgger; Nielsen, John

    2017-01-27

    Taking advantage of microwave-assisted synthesis, efficient and expedite procedures for preparation of a library of fusaric acid and 39 analogues are reported. The fusaric acid analogues were tested in cell-based screening assays for inhibition of the las and rhl quorum sensing system in Pseudomonas aeruginosa and the lux quorum sensing system in Vibrio fischeri. Eight of the 40 compounds in the library including fusaric acid inhibited lux quorum sensing and one compound inhibited activity of the las quorum sensing system. To our delight, none of the compounds showed growth inhibitory effects in the tested concentration ranges. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  14. Clinical manifestations and bacteriological features of culture-proven Gram-negative bacterial arthritis

    Directory of Open Access Journals (Sweden)

    Wei-Ting Lin

    2017-08-01

    Conclusion: Approximately 25% of cases of septic arthritis were due to GNB and resistance to commonly used antimicrobial agents was common. Liver cirrhosis and concomitant bacteremia were significant risk factors for death.

  15. BACTERIAL PREVALENCE, ANTIBIOTIC SENSITIVITY PATTERN AND PREDISPOSING FACTORS IN PATIENTS OF NOSOCOMIAL URINARY TRACT INFECTION (UTI VISITED THE TERTIARY CARE HOSPITAL IN JAMNAGAR REGION, WESTERN GUJARAT, INDIA

    Directory of Open Access Journals (Sweden)

    Prakash Somabhai Modi

    2017-08-01

    Full Text Available BACKGROUND Nosocomial UTI is the most common bacterial infection ranging from asymptomatic bacterial to septicaemia. Gram-negative bacteria contribute 80-85% of UTI and 15-20% by gram positive with major contribution by E. coli. The aim of the study is to assess the bacterial prevalence, drug sensitivity pattern and predisposing factors in nosocomial UTI. MATERIALS AND METHODS 778 midstream urine samples were tested by conventional methods of which 282 (36.25% samples were identified as positive for bacteria. All the isolates were subjected to antibiotic sensitivity testing. Statistical analysis was done by Chi-square test. RESULTS Bacterial prevalence was 36.25%. 87.95% UTI were caused by gram negative while 12.05% cases were due to gram-positive bacteria. Most prevalent bacterium was E. coli (48.23%. Piperacillin+tazobactam were identified as most sensitive drug for all gram-negative isolates. Among the gram-positive isolates, coagulase-positive bacteria like Staph aureus were sensitive to all tested drugs while coagulase-negative bacteria were less sensitive to all exposed drugs and Enterococcus produced 75% sensitivity rate to vancomycin, teicoplanin and linezolid. UTI was common between 40-60 years (37.23% with mean age 44.23±20.05 and P value was >0.05. High frequency observed in men (55.32% than women (44.68%, (P >0.05. 53.19% cases had history of catheterisation (P <0.001. CONCLUSION Variable sensitivity pattern and increasing drug resistance observed in uropathogen, so study emphasise over antibiotic sensitivity testing before prescribing empirical therapy, understanding the risk factors helps to contain the UTI.

  16. Synthetic Cationic Peptide IDR-1002 Provides Protection against Bacterial Infections through Chemokine Induction and Enhanced Leukocyte Recruitment

    DEFF Research Database (Denmark)

    Nijnik, Anastasia; Madera, Laurence; Ma, Shuhua

    2010-01-01

    , an immunomodulatory peptide IDR-1002 was selected from a library of bactenecin derivatives based on its substantially more potent ability to induce chemokines in human PBMCs. The enhanced chemokine induction activity of the peptide in vitro correlated with stronger protective activity in vivo in the Staphylococcus......With the rapid rise in the incidence of multidrug resistant infections, there is substantial interest in host defense peptides as templates for production of new antimicrobial therapeutics. Natural peptides are multifunctional mediators of the innate immune response, with some direct antimicrobial...... aureus-invasive infection model, with a >5-fold reduction in the protective dose in direct comparison with IDR-1. IDR-1002 also afforded protection against the Gram-negative bacterial pathogen Escherichia coli. Chemokine induction by IDR-1002 was found to be mediated through a Gi-coupled receptor...

  17. 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.

  18. 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.

  19. Klebsiella Species Infections in the Department of the Navy [DoN] and Department of Defense [DoD]: Annual Report 2014

    Science.gov (United States)

    2016-03-14

    2016 EpiData Center Department 2 Introduction Gram-negative bacterial infections caused by organisms in the genus Klebsiella, from the family...the few effective treatment options against drug -resistant, gram-negative organisms. 2 In the early 2000s, resistance to carbapenems emerged among...confer resistance to additional antibiotic classes, resulting in a wide range of resistance patterns including extensively drug -resistant (XDR

  20. 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.

  1. Amide side chain amphiphilic polymers disrupt surface established bacterial bio-films and protect mice from chronic Acinetobacter baumannii infection.

    Science.gov (United States)

    Uppu, Divakara S S M; Samaddar, Sandip; Ghosh, Chandradhish; Paramanandham, Krishnamoorthy; Shome, Bibek R; Haldar, Jayanta

    2016-01-01

    Bacterial biofilms represent the root-cause of chronic or persistent infections in humans. Gram-negative bacterial infections due to nosocomial and opportunistic pathogens such as Acinetobacter baumannii are more difficult to treat because of their inherent and rapidly acquiring resistance to antibiotics. Due to biofilm formation, A. baumannii has been noted for its apparent ability to survive on artificial surfaces for an extended period of time, therefore allowing it to persist in the hospital environment. Here we report, maleic anhydride based novel cationic polymers appended with amide side chains that disrupt surface established multi-drug resistant A. baumannii biofilms. More importantly, these polymers significantly (p polymers also show potent antibacterial efficacy against methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococci (VRE) and multi-drug resistant clinical isolates of A. baumannii with minimal toxicity to mammalian cells. We observe that optimal hydrophobicity dependent on the side chain chemical structure of these polymers dictate the selective toxicity to bacteria. Polymers interact with the bacterial cell membranes by causing membrane depolarization, permeabilization and energy depletion. Bacteria develop rapid resistance to erythromycin and colistin whereas no detectable development of resistance occurs against these polymers even after several passages. These results suggest the potential use of these polymeric biomaterials in disinfecting biomedical device surfaces after the infection has become established and also for the topical treatment of chronic bacterial infections. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. [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

  3. Bacterial Isolates in Neonatal Infections | Ugochukwu | Nigerian ...

    African Journals Online (AJOL)

    The single antibiotic with 100.0% sensitivity of Staph aureus and gram-negative bacteria was ciprofloxacin 28.6% of Staph aureus was sensitive to cloxacillin and genticin. Genticin was 100.0% effective against Pseudomonas but 33.3% in other coliforms. The cephalosporins had lower sensitivities. The tide of emergence of ...

  4. 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.

  5. Surface charge-conversion polymeric nanoparticles for photodynamic treatment of urinary tract bacterial infections

    International Nuclear Information System (INIS)

    Liu, Shijie; Shao, Chen; Qiao, Shenglin; Li, Lili; Qi, Guobin; Lin, Yaoxin; Qiao, Zengying; Wang, Hao

    2015-01-01

    Urinary tract infections are typical bacterial infections which result in a number of economic burdens. With increasing antibiotic resistance, it is urgent that new approaches are explored that can eliminate pathogenic bacteria without inducing drug resistance. Antimicrobial photodynamic therapy (PDT) is a new promising tactic. It is a gentle in situ photochemical reaction in which a photosensitizer (PS) generates reactive oxygen species (ROS) under laser irradiation. In this work, we have demonstrated Chlorin e6 (Ce6) encapsulated charge-conversion polymeric nanoparticles (NPs) for efficiently targeting and killing pathogenic bacteria in a weakly acidic urinary tract infection environment. Owing to the surface charge conversion of NPs in an acidic environment, the NPs exhibited enhanced recognition for Gram-positive (ex. S. aureus) and Gram-negative (ex. E. coli) bacteria due to the charge interaction. Also, those NPs showed significant antibacterial efficacy in vitro with low cytotoxicity. The MIC value of NPs to E. coli is 17.91 μg ml −1 , compared with the free Ce6 value of 29.85 μg ml −1 . Finally, a mouse acute cystitis model was used to assess the photodynamic therapy effects in urinary tract infections. A significant decline (P < 0.05) in bacterial cells between NPs and free Ce6 occurred in urine after photodynamic therapy treatment. And the plated counting results revealed a remarkable bacterial cells drop (P < 0.05) in the sacrificed bladder tissue. Above all, this nanotechnology strategy opens a new door for the treatment of urinary tract infections with minimal side effects. (paper)

  6. Surface charge-conversion polymeric nanoparticles for photodynamic treatment of urinary tract bacterial infections

    Science.gov (United States)

    Liu, Shijie; Qiao, Shenglin; Li, Lili; Qi, Guobin; Lin, Yaoxin; Qiao, Zengying; Wang, Hao; Shao, Chen

    2015-12-01

    Urinary tract infections are typical bacterial infections which result in a number of economic burdens. With increasing antibiotic resistance, it is urgent that new approaches are explored that can eliminate pathogenic bacteria without inducing drug resistance. Antimicrobial photodynamic therapy (PDT) is a new promising tactic. It is a gentle in situ photochemical reaction in which a photosensitizer (PS) generates reactive oxygen species (ROS) under laser irradiation. In this work, we have demonstrated Chlorin e6 (Ce6) encapsulated charge-conversion polymeric nanoparticles (NPs) for efficiently targeting and killing pathogenic bacteria in a weakly acidic urinary tract infection environment. Owing to the surface charge conversion of NPs in an acidic environment, the NPs exhibited enhanced recognition for Gram-positive (ex. S. aureus) and Gram-negative (ex. E. coli) bacteria due to the charge interaction. Also, those NPs showed significant antibacterial efficacy in vitro with low cytotoxicity. The MIC value of NPs to E. coli is 17.91 μg ml-1, compared with the free Ce6 value of 29.85 μg ml-1. Finally, a mouse acute cystitis model was used to assess the photodynamic therapy effects in urinary tract infections. A significant decline (P < 0.05) in bacterial cells between NPs and free Ce6 occurred in urine after photodynamic therapy treatment. And the plated counting results revealed a remarkable bacterial cells drop (P < 0.05) in the sacrificed bladder tissue. Above all, this nanotechnology strategy opens a new door for the treatment of urinary tract infections with minimal side effects.

  7. Rationale and prospects of targeting bacterial two-component systems for antibacterial treatment of cystic fibrosis patients

    NARCIS (Netherlands)

    Velikova, Nadya; Wells, Jerry M.

    2016-01-01

    Bacterial respiratory infections are the main reason of morbidity and mortality among cystic fibrosis (CF) patients. In early childhood, the respiratory infections are due to Staphylococcus aureus and Haemophilus influenzae. In older CF patients, pathogenic Gram-negative bacteria like Achromobacter

  8. 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...

  9. 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...

  10. Metagenomic Diagnosis of Bacterial Infections

    Science.gov (United States)

    Nakamura, Shota; Maeda, Norihiro; Miron, Ionut Mihai; Yoh, Myonsun; Izutsu, Kaori; Kataoka, Chidoh; Honda, Takeshi; Yasunaga, Teruo; Nakaya, Takaaki; Kawai, Jun; Hayashizaki, Yoshihide; Horii, Toshihiro

    2008-01-01

    To test the ability of high-throughput DNA sequencing to detect bacterial pathogens, we used it on DNA from a patient’s feces during and after diarrheal illness. Sequences showing best matches for Campylobacter jejuni were detected only in the illness sample. Various bacteria may be detectable with this metagenomic approach. PMID:18976571

  11. [Risk factors of bacterial nosocomial infection after pediatric liver transplantation].

    Science.gov (United States)

    Zhu, H; Gao, W

    2017-08-02

    Objective: To analyze the risk factors of nosocomial infection after liver transplantation in children, so as to provide scientific evidence for the prevention and control of nosocomial infection. Method: Clinical data of 223 pediatric patients undergoing liver transplantation between January 2014 and December 2015 were analyzed retrospectively. Univariate and multivariate analyses were carried out to investigate the risk factors of infection after transplantation. Result: Totally 51 children were infected among the 223 patients, the infection rate was 22.86%(51/223). Among the 74 cases with infection, 38 were infected with the blood (included peripherally inserted central catheters) accounting for 51.35 %; and surgical site infection accounted for 21.62%, the respiratory tract infections accounted for 18.92% and the other infections accounted for 8.11%. Totally 74 strains of infectious pathogens were found in 51 cases of infected patients, including Gram-negative bacteria accounting for 48.65%, Gram-positive bacteria accounting for 44.59% and the fungus accounting for 6.76%. According to a variety of survey factors, univariate analysis showed factors of hospitalization time, hospitalization time before surgery, surgical duration, and reoperation had statistically significant association with nosocomial infection( P nosocomial infection after pediatric liver transplantation. Conclusion: There are a variety of risk factors for the postoperative infections after liver transplantation in children. It is necessary to take into account the surgery factor, medical staff factor and hospital management factor. Management strengthening of these factors is necessary to reduce the infection rate.

  12. Technetium-99m labelled antimicrobial peptides discriminate between bacterial infections and sterile inflammations

    International Nuclear Information System (INIS)

    Welling, M.M.; Pauwels, E.K.J.; Paulusma-Annema, A.; Nibbering, P.H.; Balter, H.S.

    2000-01-01

    The aim of this study was to select technetium-99m labelled peptides that can discriminate between bacterial infections and sterile inflammations. For this purpose, we first assessed the binding of various 99m Tc-labelled natural or synthetic peptides, which are based on the sequence of the human antimicrobial peptide ubiquicidin (UBI) or human lactoferrin (hLF), to bacteria and to leucocytes in vitro. In order to select peptides that preferentially bind to bacteria over host cells, radiolabelled peptides were injected into mice intraperitoneally infected with Klebsiella pneumoniae (K. pneumoniae) and the amount of radioactivity associated with the bacteria and with the leucocytes was quantitated. The next phase focussed on discrimination between bacterial infections and sterile inflammatory processes using 99m Tc-labelled peptides in mice intramuscularly infected with various bacteria (e.g. multi-drug-resistant Staphylococcus aureus) and in animals that had been injected with lipopolysaccharides (LPS) of bacterial origin to create a sterile inflammatory process. Also, we studied the distribution of 99m Tc-labelled UBI 29-41 and UBI 18-35 in rabbits having an experimental thigh muscle infection with K. pneumoniae and in rabbits injected with LPS. Based on the results of our in vitro and in vivo binding assays, two peptides, i.e. UBI 29-41 and UBI 18-35, were selected as possible candidates for infection imaging. The radiolabelled peptides can detect infections with both gram-positive and gram-negative bacteria in mice as early as 5-30 min after injection, with a target-to-non-target (T/NT) ratio between 2 and 3; maximum T/NT ratios were seen within 1 h after injection. In rabbits, high T/NT ratios (>5) for 99m Tc-labelled UBI 29-41 were observed from 1 h after injection. No accumulation of the selected 99m Tc-labelled UBI-derived peptides was observed in thighs of mice and rabbits previously injected with LPS. Scintigraphic investigation into the biodistribution of

  13. 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

  14. Sustainable strategies for treatment of bacterial infections

    DEFF Research Database (Denmark)

    Molin, Søren

    2014-01-01

    Resistance to antibiotics and the consequential failures of treatment based on antibiotics makes microbial infections a major threat to human health. This problem combined with rapidly increasing life-style disease problems challenge our healtcare system as well as the pharma industry, and if we do...... not in a foreseeable future develop novel approaches and strategies to combat bacterial infections, many people will be at risk of dying from even trivial infections for which we until recently had highly effective antibiotics. We have for a number of years investigated chronic bacterial lung infections in patients...... suffering from cystic fibrosis. These infections are optimal model scenarios for studies of antibiotic resistance development and microbial adaptation, and we suggest that this information should be useful when designing new anti-microbial strategies. In this respect it will be important to choose...

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

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

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    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.

  3. Prevalence and Characterization of Multi-Drug-Resistant Gram-Negative Bacilli Isolated From Lebanese Poultry: A Nationwide Study

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    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

  4. 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

  5. Immunity to bacterial infection in the chicken.

    Science.gov (United States)

    Wigley, Paul

    2013-11-01

    Bacterial infections remain important to the poultry industry both in terms of animal and public health, the latter due to the importance of poultry as a source of foodborne bacterial zoonoses such as Salmonella and Campylobacter. As such, much focus of research to the immune response to bacterial infection has been to Salmonella. In this review we will focus on how research on avian salmonellosis has developed our understanding of immunity to bacteria in the chicken from understanding the role of TLRs in recognition of bacterial pathogens, through the role of heterophils, macrophages and γδ lymphocytes in innate immunity and activation of adaptive responses to the role of cellular and humoral immunity in immune clearance and protection. What is known of the immune response to other bacterial infections and in particular infections that have emerged recently as major problems in poultry production including Campylobacter jejuni, Avian Pathogenic Escherichia coli, Ornithobacterium rhinotracheale and Clostridium perfringens are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

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    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.

  7. Effectiveness of oral hygiene interventions against oral and oropharyngeal reservoirs of aerobic and facultatively anaerobic gram-negative bacilli.

    Science.gov (United States)

    Lam, Otto L T; McGrath, Colman; Li, Leonard S W; Samaranayake, Lakshman P

    2012-03-01

    Aerobic and facultatively anaerobic gram-negative bacilli (AGNB) are opportunistic pathogens and continue to cause a large number of hospital-acquired infections. AGNB residing in the oral cavity and oropharynx have been linked to nosocomial pneumonia and septicemia. Although AGNB are not considered members of the normal oral and oropharyngeal flora, medically compromised patients have been demonstrated to be susceptible to AGNB colonization. A literature search was conducted to retrieve articles that evaluated the effectiveness of oral hygiene interventions in reducing the oral and oropharyngeal carriage of AGNB in medically compromised patients. Few studies have documented the use of mechanical oral hygiene interventions alone against AGNB. Although a number of studies have employed oral hygiene interventions complemented by antiseptic agents such as chlorhexidine and povidone iodine, there appears to be a discrepancy between their in vitro and in vivo effectiveness. With the recognition of the oral cavity and oropharynx as a reservoir of AGNB and the recent emergence of multidrug and pandrug resistance in hospital settings, there is a pressing need for additional high-quality randomized controlled trials to determine which oral hygiene interventions or combination of interventions are most effective in eliminating or reducing AGNB carriage. Copyright © 2012 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  8. Mucin dynamics in intestinal bacterial infection.

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    Sara K Lindén

    Full Text Available Bacterial gastroenteritis causes morbidity and mortality in humans worldwide. Murine Citrobacter rodentium infection is a model for gastroenteritis caused by the human pathogens enteropathogenic Escherichia coli and enterohaemorrhagic E. coli. Mucin glycoproteins are the main component of the first barrier that bacteria encounter in the intestinal tract.Using Immunohistochemistry, we investigated intestinal expression of mucins (Alcian blue/PAS, Muc1, Muc2, Muc4, Muc5AC, Muc13 and Muc3/17 in healthy and C. rodentium infected mice. The majority of the C. rodentium infected mice developed systemic infection and colitis in the mid and distal colon by day 12. C. rodentium bound to the major secreted mucin, Muc2, in vitro, and high numbers of bacteria were found in secreted MUC2 in infected animals in vivo, indicating that mucins may limit bacterial access to the epithelial surface. In the small intestine, caecum and proximal colon, the mucin expression was similar in infected and non-infected animals. In the distal colonic epithelium, all secreted and cell surface mucins decreased with the exception of the Muc1 cell surface mucin which increased after infection (p<0.05. Similarly, during human infection Salmonella St Paul, Campylobacter jejuni and Clostridium difficile induced MUC1 in the colon.Major changes in both the cell-surface and secreted mucins occur in response to intestinal infection.

  9. 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.

  10. S-layer proteins from Lactobacillus sp. inhibit bacterial infection by blockage of DC-SIGN cell receptor.

    Science.gov (United States)

    Prado Acosta, Mariano; Ruzal, Sandra M; Cordo, Sandra M

    2016-11-01

    Many species of Lactobacillus sp. possess Surface(s) layer proteins in their envelope. Among other important characteristics S-layer from Lactobacillus acidophilus binds to the cellular receptor DC-SIGN (Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin; CD209), which is involved in adhesion and infection of several families of bacteria. In this report we investigate the activity of new S-layer proteins from the Lactobacillus family (Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus helveticus and Lactobacillus kefiri) over the infection of representative microorganisms important to human health. After the treatment of DC-SIGN expressing cells with these proteins, we were able to diminish bacterial infection by up to 79% in both gram negative and mycobacterial models. We discovered that pre-treatment of the bacteria with S-layers from Lactobacillus acidophilus and Lactobacillus brevis reduced bacteria viability but also prevent infection by the pathogenic bacteria. We also proved the importance of the glycosylation of the S-layer from Lactobacillus kefiri in the binding to the receptor and thus inhibition of infection. This novel characteristic of the S-layers proteins may contribute to the already reported pathogen exclusion activity for these Lactobacillus probiotic strains; and might be also considered as a novel enzymatic antimicrobial agents to inhibit bacterial infection and entry to host cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Evaluation of Antimicrobial Activity of Cuminum Cyminum Essential Oil and Extract against Bacterial Strains Isolated from Patients with Symptomatic Urinary Tract Infection

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    Yasaman Saee

    2016-10-01

    Full Text Available Background: Many efforts have been done to find effective agents against resistant pathogens. Cuminum cyminum L. (Cumin is an aromatic plant within the Apiaceae family. It has a variety of purposes and demonstrates antimicrobial and antioxidant properties. This study evaluated the activity of C. cyminum extract and essential oil against bacterial isolates which cause urinary tract infection, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Streptococcus agalactiae, group A streptococci, Enterococcus faecalis, Staphylococcus epidermidis, Staphylococcus aureus and Staphylococcus saprophyticus isolated from patients with urinary tract infection.Materials and Methods: Extract was prepared by maceration and essential oil was prepared by hydrodistillation from C. cyminum seeds. The study population was 95 patients with urinary tract infection without malignant diseases, diabetes and immunosupression. After identification of organism, susceptibility testing was carried out by disc diffusion method and MIC values by broth microdilution testing.Results: C. cyminum essential oil can have a better effect on the gram-negative bacteria causing urinary tract infection than gram-positive bacteria. In addition, C. cyminum extract have good activity against both gram- positive and gram-negative bacteria. Our findings also showed that essential oil and extract of C. cyminum has better antibacterial activity on uropathogen isolates than amoxicillin and the difference was significant (P value<0.05 but the activity is not superior to other antibiotics.Conclusion: These results suggest that the essential oil and extract of C. cyminum seeds might be considered as interesting sources of antibacterial components against uropathogenic bacteria.

  12. Bacterial isolates from burn wound infections and their antibiograms: A eight-year study

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    Mehta Manjula

    2007-01-01

    Full Text Available Background: Infection is an important cause of mortality in burns. Rapidly emerging nosocomial pathogens and the problem of multi-drug resistance necessitates periodic review of isolation patterns and antibiogram in the burn ward. Aim: Keeping this in mind, the present retrospective study from wounds of patients admitted to burns unit was undertaken to determine the bacteriological profile and the resistance pattern from the burn ward over a period of three years (June 2002 to May 2005 and was compared with the results obtained during the previous five years (June 1997-May 2002, to ascertain any change in the bacteriological profile and antimicrobial resistance pattern. Materials and Methods: Bacterial isolates from 268 wound swabs taken from burn patients were identified by conventional biochemical methods and antimicrobial susceptibility was performed. Statistical comparison of bacterial isolates and their resistance pattern with previous five years data was done using c2 test. Results and Conclusions: During the period from 2002 to 2005 Pseudomonas species was the commonest pathogen isolated (51.5% followed by Acinetobacter species (14.28%, Staph. aureus (11.15%, Klebsiella species (9.23% and Proteus species (2.3%. When compared with the results of the previous five years i.e., 1997 to 2002, Pseudomonas species was still the commonest pathogen in the burns unit. However, the isolation of this organism and other gram-negative organisms had decreased in comparison to previous years. Newer drugs were found to be effective.

  13. 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

  14. 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.

  15. Secondary bacterial infection in Ghanaian patients with scabies.

    Science.gov (United States)

    Adjei, O; Brenya, R C

    1997-11-01

    From 110 patients with secondarily infected scabies lesions, 105 bacteria consisting of 66 aerobes and 39 anaerobes were isolated. A mixture of aerobic and anaerobic bacteria was present in 15 (13.6%). The predominant aerobic and anaerobic bacteria were staphylococcous aureus 39.1% and pepostreptococcus spp. 14.2% respectively. Organisms that resided in the mucus membranes close to or in contact with the lesions predominated in those infections. Most organisms were recovered from the finger and buttock lesions. These organisms were mainly staph. aureus, beta-haemolytic streptococci group. A and peptostreptococcus. More than 80% of staph. aureus isolated were resistant to penicillin. Less than 20% of the anaerobes were resistant to penicillin. The enteric Gram-negative, E. coli and Klebsiella spp. showed 100% sensitivity to Amoxycilin/clavulanic acid and gentamicin. Pseudomonas spp. were only susceptible to gentamicin, Amoxycillin/clavulanic acid proved to be the most active therapeutic agent in in vitro against the isolated microorganisms.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

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

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    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.

  4. Comparison of gram-negative and gram-positive hematogenous pyogenic spondylodiscitis: clinical characteristics and outcomes of treatment.

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    Lee, Ching-Yu; Wu, Meng-Huang; Cheng, Chin-Chang; Huang, Tsung-Jen; Huang, Tsung-Yu; Lee, Chien-Yin; Huang, Jou-Chen; Li, Yen-Yao

    2016-12-06

    To the best of our knowledge, no study has compared gram-negative bacillary hematogenous pyogenic spondylodiscitis (GNB-HPS) with gram-positive coccal hematogenous pyogenic spondylodiscitis (GPC-HPS) regarding their clinical characteristics and outcomes. From January 2003 to January 2013, 54 patients who underwent combined antibiotic and surgical therapy in the treatment of hematogenous pyogenic spondylodiscitis were included. Compared with 37 GPC-HPS patients, the 17 GNB-HPS patients were more often found to be older individuals, a history of cancer, and a previous history of symptomatic urinary tract infection. They also had a less incidence of epidural abscess formation compared with GPC-HPS patients from findings on magnetic resonance imaging (MRI). Constitutional symptoms were the primary reasons for initial physician visits in GNB-HPS patients whereas pain in the affected spinal region was the most common manifestation in GPC-HPS patients at initial visit. The clinical outcomes of GNB-HPS patients under combined surgical and antibiotic treatment were not different from those of GPC-HPS patients. In multivariate analysis, independent predicting risk factors for GNB-HPS included a malignant history and constitutional symptoms and that for GPC-HPS was epidural abscess. The clinical manifestations and MRI presentations of GNB-HPS were distinguishable from those of GPC-HPS.

  5. Under-utilization of taps in intensive care unit as a cause of reservoirs of nonfermenting gram-negative bacilli.

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    de-Las-Casas-Cámara, Gonzalo; Martín-Ríos, María Dolores; Adillo-Montero, Maria Isabel; Muñoz-Egea, María Carmen; Zapardiel-Ferrero, Javier; Pérez-Jorge Peremarch, Concepción

    2017-03-10

    The under-utilisation of taps is associated with the generation of reservoirs of non-fermenting gram-negative bacilli with the ability to disseminate. We describe the detection and approach of the problem in an ICU. Observational descriptive study in an ICU with individual cubicles with their own sink. We collected clinical samples from patients and environmental samples from tap aerators and reviewed the unit's hygiene measures. We detected four cases due to Chryseobacterium indologenes, one to Elizabethkingia meningoseptica and another to Pseudomonas aeruginosa; they were identified both in clinical and the environmental samples. The healthcare professionals reported that almost every hand hygiene opportunity was performed with a hydroalcoholic solution. After considered the daily flushing of water outlets as inefficient, it was decided to remove them. National recommendations were insufficient for preventing, detecting and controlling tap contamination in units with a high risk of infection. The management of taps in these units needs to be improved. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

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

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    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.

  7. Epidemiological analysis of bacterial strains involved in hospital infection in a University Hospital from Brazil

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    MORAES Bianca Aguiar de

    2000-01-01

    Full Text Available Hospital infections cause an increase in morbidity and mortality of hospitalized patients with significant rise in hospital costs. The aim of this work was an epidemiological analysis of hospital infection cases occurred in a public University Hospital in Rio de Janeiro. Hence, 238 strains were isolated from 14 different clinical materials of 166 patients hospitalized in the period between August 1995 and July 1997. The average age of the patients was 33.4 years, 72.9% used antimicrobials before having a positive culture. The most common risk conditions were surgery (19.3%, positive HIV or AIDS (18.1% and lung disease (16.9%. 24 different bacterial species were identified, S. aureus (21% and P. aeruginosa (18.5% were predominant. Among 50 S. aureus isolated strains 36% were classified as MRSA (Methicillin Resistant S. aureus. The Gram negative bacteria presented high resistance to aminoglycosides and cephalosporins. A diarrhea outbreak, detected in high-risk neonatology ward, was caused by Salmonella serovar Infantis strain, with high antimicrobial resistance and a plasmid of high molecular weight (98Mda containing virulence genes and positive for R factor.

  8. Bacterial Infection and Immune Responses in Lutzomyia longipalpis Sand Fly Larvae Midgut.

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    Matthew Heerman

    Full Text Available The midgut microbial community in insect vectors of disease is crucial for an effective immune response against infection with various human and animal pathogens. Depending on the aspects of their development, insects can acquire microbes present in soil, water, and plants. Sand flies are major vectors of leishmaniasis, and shown to harbor a wide variety of Gram-negative and Gram-positive bacteria. Sand fly larval stages acquire microorganisms from the soil, and the abundance and distribution of these microorganisms may vary depending on the sand fly species or the breeding site. Here, we assess the distribution of two bacteria commonly found within the gut of sand flies, Pantoea agglomerans and Bacillus subtilis. We demonstrate that these bacteria are able to differentially infect the larval digestive tract, and regulate the immune response in sand fly larvae. Moreover, bacterial distribution, and likely the ability to colonize the gut, is driven, at least in part, by a gradient of pH present in the gut.

  9. Bacterial Infection and Immune Responses in Lutzomyia longipalpis Sand Fly Larvae Midgut

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    Heerman, Matthew; Weng, Ju-Lin; Hurwitz, Ivy; Durvasula, Ravi; Ramalho-Ortigao, Marcelo

    2015-01-01

    The midgut microbial community in insect vectors of disease is crucial for an effective immune response against infection with various human and animal pathogens. Depending on the aspects of their development, insects can acquire microbes present in soil, water, and plants. Sand flies are major vectors of leishmaniasis, and shown to harbor a wide variety of Gram-negative and Gram-positive bacteria. Sand fly larval stages acquire microorganisms from the soil, and the abundance and distribution of these microorganisms may vary depending on the sand fly species or the breeding site. Here, we assess the distribution of two bacteria commonly found within the gut of sand flies, Pantoea agglomerans and Bacillus subtilis. We demonstrate that these bacteria are able to differentially infect the larval digestive tract, and regulate the immune response in sand fly larvae. Moreover, bacterial distribution, and likely the ability to colonize the gut, is driven, at least in part, by a gradient of pH present in the gut. PMID:26154607

  10. Biofilm Formation and Detachment in Gram-Negative Pathogens Is Modulated by Select Bile Acids.

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    Laura M Sanchez

    Full Text Available Biofilms are a ubiquitous feature of microbial community structure in both natural and host environments; they enhance transmission and infectivity of pathogens and provide protection from human defense mechanisms and antibiotics. However, few natural products are known that impact biofilm formation or persistence for either environmental or pathogenic bacteria. Using the combination of a novel natural products library from the fish microbiome and an image-based screen for biofilm inhibition, we describe the identification of taurine-conjugated bile acids as inhibitors of biofilm formation against both Vibrio cholerae and Pseudomonas aeruginosa. Taurocholic acid (1 was isolated from the fermentation broth of the fish microbiome-derived strain of Rhodococcus erythropolis and identified using standard NMR and MS methods. Screening of the twelve predominant human steroidal bile acid components revealed that a subset of these compounds can inhibit biofilm formation, induce detachment of preformed biofilms under static conditions, and that these compounds display distinct structure-activity relationships against V. cholerae and P. aeruginosa. Our findings highlight the significance of distinct bile acid components in the regulation of biofilm formation and dispersion in two different clinically relevant bacterial pathogens, and suggest that the bile acids, which are endogenous mammalian metabolites used to solubilize dietary fats, may also play a role in maintaining host health against bacterial infection.

  11. Optimising Antibiotic Usage to Treat Bacterial Infections

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    Paterson, Iona K.; Hoyle, Andy; Ochoa, Gabriela; Baker-Austin, Craig; Taylor, Nick G. H.

    2016-11-01

    The increase in antibiotic resistant bacteria poses a threat to the continued use of antibiotics to treat bacterial infections. The overuse and misuse of antibiotics has been identified as a significant driver in the emergence of resistance. Finding optimal treatment regimens is therefore critical in ensuring the prolonged effectiveness of these antibiotics. This study uses mathematical modelling to analyse the effect traditional treatment regimens have on the dynamics of a bacterial infection. Using a novel approach, a genetic algorithm, the study then identifies improved treatment regimens. Using a single antibiotic the genetic algorithm identifies regimens which minimise the amount of antibiotic used while maximising bacterial eradication. Although exact treatments are highly dependent on parameter values and initial bacterial load, a significant common trend is identified throughout the results. A treatment regimen consisting of a high initial dose followed by an extended tapering of doses is found to optimise the use of antibiotics. This consistently improves the success of eradicating infections, uses less antibiotic than traditional regimens and reduces the time to eradication. The use of genetic algorithms to optimise treatment regimens enables an extensive search of possible regimens, with previous regimens directing the search into regions of better performance.

  12. Empiric Antibiotic Therapy of Nosocomial Bacterial Infections.

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    Reddy, Pramod

    2016-01-01

    Broad-spectrum antibiotics are commonly used by physicians to treat various infections. The source of infection and causative organisms are not always apparent during the initial evaluation of the patient, and antibiotics are often given empirically to patients with suspected sepsis. Fear of attempting cephalosporins and carbapenems in penicillin-allergic septic patients may result in significant decrease in the spectrum of antimicrobial coverage. Empiric antibiotic therapy should sufficiently cover all the suspected pathogens, guided by the bacteriologic susceptibilities of the medical center. It is important to understand the major pharmacokinetic properties of antibacterial agents for proper use and to minimize the development of resistance. In several septic patients, negative cultures do not exclude active infection and positive cultures may not represent the actual infection. This article will review the important differences in the spectrum of commonly used antibiotics for nosocomial bacterial infections with a particular emphasis on culture-negative sepsis and colonization.

  13. Secondary Bacterial Infections Associated with Influenza Pandemics

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    Denise E. Morris

    2017-06-01

    Full Text Available Lower and upper respiratory infections are the fourth highest cause of global mortality (Lozano et al., 2012. Epidemic and pandemic outbreaks of respiratory infection are a major medical concern, often causing considerable disease and a high death toll, typically over a relatively short period of time. Influenza is a major cause of epidemic and pandemic infection. Bacterial co/secondary infection further increases morbidity and mortality of influenza infection, with Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus reported as the most common causes. With increased antibiotic resistance and vaccine evasion it is important to monitor the epidemiology of pathogens in circulation to inform clinical treatment and development, particularly in the setting of an influenza epidemic/pandemic.

  14. Using Natural Products to Treat Resistant and Persistent Bacterial Infections

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    Deering, Robert W.

    Antimicrobial resistance is a growing threat to human health both worldwide and in the United States. Most concerning is the emergence of multi-drug resistant (MDR) bacterial pathogens, especially the 'ESKAPE' pathogens for which treatment options are dwindling. To complicate the problem, approvals of antibiotic drugs are extremely low and many research and development efforts in the pharmaceutical industry have ceased, leaving little certainty that critical new antibiotics are nearing the clinic. New antibiotics are needed to continue treating these evolving infections. In addition to antibiotics, approaches that aim to inhibit or prevent antimicrobial resistance could be useful. Also, studies that improve our understanding of bacterial pathophysiology could lead to new therapies for infectious disease. Natural products, especially those from the microbial world, have been invaluable as resources for new antibacterial compounds and as insights into bacterial physiology. The goal of this dissertation is to find new ways to treat resistant bacterial infections and learn more about the pathophysiology of these bacteria. Investigations of natural products to find molecules able to be used as new antibiotics or to modulate resistance and other parts of bacterial physiology are crucial aspects of the included studies. The first included study, which is reported in chapter two, details a chemical investigation of a marine Pseudoalteromonas sp. Purification efforts of the microbial metabolites were guided by testing against a resistance nodulation of cell division model of efflux pumps expressed in E. coli. These pumps play an important role in the resistance of MDR Gram negative pathogens such as Pseudomonas aeruginosa and Enterobacteriaceae. Through this process, 3,4-dibromopyrrole-2,5-dione was identified as a potent inhibitor of the RND efflux pumps and showed synergistic effects against the E. coli strain with common antibiotics including fluoroquinolones, beta

  15. Prevention of bacterial and fungal infections in acute leukemia patients: a new and potent combination of oral norfloxacin and amphotericin B.

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    Yamada, T; Dan, K; Nomura, T

    1993-09-01

    The effect of a combination regimen using norfloxacin (NFLX) and amphotericin B (AMPH-B) for prevention of infections in patients with acute leukemia being treated by remission-induction chemotherapy in a randomized, controlled trial was studied. One hundred and six consecutive, evaluable patients were randomly assigned to receive orally 200 mg of norfloxacin two or four times daily and 200 mg of amphotericin B four times daily, or amphotericin B only. A smaller percentage of patients with bacteriologically-documented infections was observed in the study group compared with the control group (34.6% vs 56.9%; P combination antimicrobial regimen is safe and effective for prevention of gram-negative bacterial as well as fungal infections in patients with acute leukemia being treated with cytotoxic remission-induction chemotherapy.

  16. A Novel 3D Skin Explant Model to Study Anaerobic Bacterial Infection

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    Grazieli Maboni

    2017-09-01

    Full Text Available Skin infection studies are often limited by financial and ethical constraints, and alternatives, such as monolayer cell culture, do not reflect many cellular processes limiting their application. For a more functional replacement, 3D skin culture models offer many advantages such as the maintenance of the tissue structure and the cell types present in the host environment. A 3D skin culture model can be set up using tissues acquired from surgical procedures or post slaughter, making it a cost effective and attractive alternative to animal experimentation. The majority of 3D culture models have been established for aerobic pathogens, but currently there are no models for anaerobic skin infections. Footrot is an anaerobic bacterial infection which affects the ovine interdigital skin causing a substantial animal welfare and financial impact worldwide. Dichelobacter nodosus is a Gram-negative anaerobic bacterium and the causative agent of footrot. The mechanism of infection and host immune response to D. nodosus is poorly understood. Here we present a novel 3D skin ex vivo model to study anaerobic bacterial infections using ovine skin explants infected with D. nodosus. Our results demonstrate that D. nodosus can invade the skin explant, and that altered expression of key inflammatory markers could be quantified in the culture media. The viability of explants was assessed by tissue integrity (histopathological features and cell death (DNA fragmentation over 76 h showing the model was stable for 28 h. D. nodosus was quantified in all infected skin explants by qPCR and the bacterium was visualized invading the epidermis by Fluorescent in situ Hybridization. Measurement of pro-inflammatory cytokines/chemokines in the culture media revealed that the explants released IL1β in response to bacteria. In contrast, levels of CXCL8 production were no different to mock-infected explants. The 3D skin model realistically simulates the interdigital skin and has

  17. Bacterial Adaptation during Chronic Respiratory Infections

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    Louise Cullen

    2015-03-01

    Full Text Available Chronic lung infections are associated with increased morbidity and mortality for individuals with underlying respiratory conditions such as cystic fibrosis (CF and chronic obstructive pulmonary disease (COPD. The process of chronic colonisation allows pathogens to adapt over time to cope with changing selection pressures, co-infecting species and antimicrobial therapies. These adaptations can occur due to environmental pressures in the lung such as inflammatory responses, hypoxia, nutrient deficiency, osmolarity, low pH and antibiotic therapies. Phenotypic adaptations in bacterial pathogens from acute to chronic infection include, but are not limited to, antibiotic resistance, exopolysaccharide production (mucoidy, loss in motility, formation of small colony variants, increased mutation rate, quorum sensing and altered production of virulence factors associated with chronic infection. The evolution of Pseudomonas aeruginosa during chronic lung infection has been widely studied. More recently, the adaptations that other chronically colonising respiratory pathogens, including Staphylococcus aureus, Burkholderia cepacia complex and Haemophilus influenzae undergo during chronic infection have also been investigated. This review aims to examine the adaptations utilised by different bacterial pathogens to aid in their evolution from acute to chronic pathogens of the immunocompromised lung including CF and COPD.

  18. Spread of TEM, VIM, SHV, and CTX-M β-Lactamases in Imipenem-Resistant Gram-Negative Bacilli Isolated from Egyptian Hospitals.

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    Hamdy Mohammed, El Sayed; Elsadek Fakhr, Ahmed; Mohammed El Sayed, Hanan; Al Johery, Said Abd Elmohsen; Abdel Ghani Hassanein, Wesam

    2016-01-01

    Carbapenem-resistant Gram-negative bacilli resulting from β-lactamases have been reported to be an important cause of nosocomial infections and are a critical therapeutic problem worldwide. This study aimed to describe the prevalence of imipenem-resistant Gram-negative bacilli isolates and detection of bla VIM, bla TEM, bla SHV, bla CTX-M-1, and bla CTX-M-9 genes in these clinical isolates in Egyptian hospitals. The isolates were collected from various clinical samples, identified by conventional methods and confirmed by API 20E. Antibiotic susceptibility testing was determined by Kirby-Bauer technique and interpreted according to CLSI. Production of bla VIM, bla TEM, bla SHV, and bla CTX-M genes was done by polymerase chain reaction (PCR). Direct sequencing from PCR products was subsequently carried out to identify and confirm these β-lactamases genes. Out of 65 isolates, (46.1%) Escherichia coli, (26.2%) Klebsiella pneumoniae, and (10.7%) Pseudomonas aeruginosa were identified as the commonest Gram-negative bacilli. 33(50.8%) were imipenem-resistant isolates. 22 isolates (66.7%) carried bla VIM, 24(72.7%) had bla TEM, and 5(15%) showed bla SHV, while 12(36%), 6(18.2%), and 0(0.00%) harbored bla CTX-M-1, bla CTX-M-9, and bla CTX-M-8/25, respectively. There is a high occurrence of β-lactamase genes in clinical isolates and sequence analysis of amplified genes showed differences between multiple SNPs (single nucleotide polymorphism) sites in the same gene among local isolates in relation to published sequences.

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

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    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.

  20. Susceptibility of important Gram-negative pathogens to tigecycline and other antibiotics in Latin America between 2004 and 2010

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    Fernández-Canigia Liliana

    2012-10-01

    Full Text Available Abstract Background The Tigecycline Evaluation and Surveillance Trial (T.E.S.T. is a global surveillance study of antimicrobial susceptibility. This study reports data from Gram-negative isolates collected from centers in Latin America between 2004 and 2010. Methods Consecutive bacterial isolates were tested at each center using broth microdilution methodology as described by the Clinical Laboratory Standards Institute (CLSI. Susceptibility was determined using the CLSI interpretive criteria. For tigecycline the US Federal Drug Administration (FDA criteria were used. Results A total of 16 232 isolates were analyzed. Susceptibility to imipenem, meropenem, and tigecycline was >95% against both non-extended-spectrum β-lactamase (ESBL and ESBL producing Escherichia coli. Susceptibility to amikacin was also >95% for non-ESBL E. coli. 24.3% of E. coli were ESBL producers, ranging from 11.2% (58/519 in Colombia to 40.3% (31/77 in Honduras. Greater than 90% of non-ESBL Klebsiella pneumoniae were susceptible to tigecycline, carbapenems and amikacin. 35.3% of K. pneumoniae were ESBL producers, ranging from 17.2% (36/209 in Venezuela to 73.3% (55/75 in Honduras, with only imipenem and tigecycline maintaining >90% susceptibility. Greater than 90% of Klebsiella oxytoca, Enterobacter spp., and Serratia marcescens were susceptible to amikacin, carbapenems and tigecycline. The highest rates of susceptibility against Acinetobacter baumannii were seen for minocycline (89.4% and imipenem (62.5%, while 95.8% of the A. baumannii isolates displayed an MIC ≤2 μg/mL for tigecycline. Conclusions In this study carbapenems and tigecycline remain active against Enterobacteriaceae and A. baumannii; however, there is cause for concern with carbapenem non-susceptible isolates reported in all countries included in this study.

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

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    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

  2. The gram-negative sensing receptor PGRP-LC contributes to grooming induction in Drosophila.

    Science.gov (United States)

    Yanagawa, Aya; Neyen, Claudine; Lemaitre, Bruno; Marion-Poll, Frédéric

    2017-01-01

    Behavioral resistance protects insects from microbial infection. However, signals inducing insect hygiene behavior are still relatively unexplored. Our previous study demonstrated that olfactory signals from microbes enhance insect hygiene behavior, and gustatory signals even induce the behavior. In this paper, we postulated a cross-talk between behavioral resistance and innate immunity. To examine this hypothesis, we employed a previously validated behavioral test to examine the function of taste signals in inducing a grooming reflex in decapitated flies. Microbes, which activate different pattern recognition systems upstream of immune pathways, were applied to see if there was any correlation between microbial perception and grooming reflex. To narrow down candidate elicitors, the grooming induction tests were conducted with highly purified bacterial components. Lastly, the role of DAP-type peptidoglycan in grooming induction was confirmed. Our results demonstrate that cleaning behavior can be triggered through recognition of DAP-type PGN by its receptor PGRP-LC.

  3. Rz/Rz1 lysis gene equivalents in phages of Gram-negative hosts.

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    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.

  4. Extended-spectrum cephalosporin-resistant Gram-negative organisms in livestock: an emerging problem for human health?

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    Seiffert, Salome N; Hilty, Markus; Perreten, Vincent; Endimiani, Andrea

    2013-01-01

    Escherichia coli, Salmonella spp. and Acinetobacter spp. are important human pathogens. Serious infections due to these organisms are usually treated with extended-spectrum cephalosporins (ESCs). However, in the past two decades we have faced a rapid increasing of infections and colonization caused by ESC-resistant (ESC-R) isolates due to production of extended-spectrum-β-lactamases (ESBLs), plasmid-mediated AmpCs (pAmpCs) and/or carbapenemase enzymes. This situation limits drastically our therapeutic armamentarium and puts under peril the human health. Animals are considered as potential reservoirs of multidrug-resistant (MDR) Gram-negative organisms. The massive and indiscriminate use of antibiotics in veterinary medicine has contributed to the selection of ESC-R E. coli, ESC-R Salmonella spp. and, to less extent, MDR Acinetobacter spp. among animals, food, and environment. This complex scenario is responsible for the expansion of these MDR organisms which may have life-threatening clinical significance. Nowadays, the prevalence of food-producing animals carrying ESC-R E. coli and ESC-R Salmonella (especially those producing CTX-M-type ESBLs and the CMY-2 pAmpC) has reached worryingly high values. More recently, the appearance of carbapenem-resistant isolates (i.e., VIM-1-producing Enterobacteriaceae and NDM-1 or OXA-23-producing Acinetobacter spp.) in livestock has even drawn greater concerns. In this review, we describe the aspects related to the spread of the above MDR organisms among pigs, cattle, and poultry, focusing on epidemiology, molecular mechanisms of resistance, impact of antibiotic use, and strategies to contain the overall problem. The link and the impact of ESC-R organisms of livestock origin for the human scenario are also discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Cephalosporins currently in early clinical trials for the treatment of bacterial infections.

    Science.gov (United States)

    Long, Timothy E; Williams, Justin T

    2014-10-01

    Healthcare-associated infections caused by multi-drug resistant bacteria remain a major cause of worldwide mortality. With the recent approval of agents such as hetero-resistant cocci (i.e., ceftaroline, ceftobiprole, telavancin) for the treatment of Gram-positive infections by and drugs like fidaxomicin for treating Clostridium difficile, present-day research on antibacterials has largely shifted to developing interventions for diseases caused by Gram-negative bacilli. Cephalosporins have gained significant interest as antipseudomonals to be used in hospitals for treating device- and procedure-associated infections. With extended-spectrum activity against many enterobacterial pathogens, the introduction of new antipseudomonal cephalosporin-based treatments will mark a significant advancement in the management of hospital-borne diseases. The following review examines the present-day status of investigational cephalosporins currently in preclinical, Phase I and Phase II stage development. The article focuses specifically on treatments used for healthcare-associated infections due to Gram-negative bacteria. There is an urgent need for new antimicrobials to treat nosocomial infections due to multi-drug resistant Gram-negative bacteria. The impending approvals of antipseudomonal cephalosporins co-formulated with a β-lactamase inhibitor will allow clinicians to treat more hetero-resistant infections with cephalosporins, while avoiding the use of more toxic agents such as colistin. The growing interest in developing new β-lactamase inhibitor combinatorial treatments with approved β-lactam antibiotics is anticipated to decrease the number of novel cephalosporins entering clinical trials this decade.

  6. 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)

  7. Antimicrobial Resistance in Invasive Bacterial Infections in Hospitalized Children, Cambodia, 2007-2016.

    Science.gov (United States)

    Fox-Lewis, Andrew; Takata, Junko; Miliya, Thyl; Lubell, Yoel; Soeng, Sona; Sar, Poda; Rith, Kolthida; McKellar, Gregor; Wuthiekanun, Vanaporn; McGonagle, Erin; Stoesser, Nicole; Moore, Catrin E; Parry, Christopher M; Turner, Claudia; Day, Nicholas P J; Cooper, Ben S; Turner, Paul

    2018-05-01

    To determine trends, mortality rates, and costs of antimicrobial resistance in invasive bacterial infections in hospitalized children, we analyzed data from Angkor Hospital for Children, Siem Reap, Cambodia, for 2007-2016. A total of 39,050 cultures yielded 1,341 target pathogens. Resistance rates were high; 82% each of Escherichia coli and Klebsiella pneumoniae isolates were multidrug resistant. Hospital-acquired isolates were more often resistant than community-acquired isolates; resistance trends over time were heterogeneous. K. pneumoniae isolates from neonates were more likely than those from nonneonates to be resistant to ampicillin-gentamicin and third-generation cephalosporins. In patients with community-acquired gram-negative bacteremia, third-generation cephalosporin resistance was associated with increased mortality rates, increased intensive care unit admissions, and 2.26-fold increased healthcare costs among survivors. High antimicrobial resistance in this setting is a threat to human life and the economy. In similar low-resource settings, our methods could be reproduced as a robust surveillance model for antimicrobial resistance.

  8. 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.

  9. 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)

  10. 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

  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. 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.

  13. Veillonella rogosae sp. nov., an anaerobic, Gram-negative coccus isolated from dental plaque

    Science.gov (United States)

    Arif, Nausheen; Do, Thuy; Byun, Roy; Sheehy, Evelyn; Clark, Douglas; Gilbert, Steven C.; Beighton, David

    2008-01-01

    Strains of a novel anaerobic, Gram-negative coccus were isolated from the supra-gingival plaque of children. Independent strains from each of six subjects were shown, at a phenotypic level and based on 16S rRNA gene sequencing, to be members of the genus Veillonella. Analysis revealed that the six strains shared 99.7 % similarity in their 16S rRNA gene sequences and 99.0 % similarity in their rpoB gene sequences. The six novel strains formed a distinct group and could be clearly separated from recognized species of the genus Veillonella of human or animal origin. The novel strains exhibited 98 and 91 % similarity to partial 16S rRNA and rpoB gene sequences of Veillonella parvula ATCC 10790T, the most closely related member of the genus. The six novel strains could be differentiated from recognized species of the genus Veillonella based on partial 16S rRNA and rpoB gene sequencing. The six novel strains are thus considered to represent a single novel species of the genus Veillonella, for which the name Veillonella rogosae sp. nov. is proposed. The type strain is CF100T (=CCUG 54233T=DSM 18960T). PMID:18319459

  14. 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)

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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)

  20. 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.

  1. Clinical study of carbapenem sensitive and resistant Gram-negative bacteremia in neutropenic and nonneutropenic patients: The first series from India.

    Science.gov (United States)

    Ghafur, A K; Vidyalakshmi, P R; Kannaian, P; Balasubramaniam, R

    2014-01-01

    Carbapenem resistance is a growing global concern. There is a lack of published clinical studies on the topic from Indian subcontinent. Aim of this study was to analyze clinical profile of patients with carbapenem sensitive and resistant bacteremia among neutropenic and nonneutropenic patients. Retrospective analysis of 141 patients who had carbapenem resistant or sensitive Gram-negative bacteremia, identified over a period of 1-year was done by medical records review, in Apollo Specialty Hospital, a 300-bedded tertiary care Oncology, neurosurgical and orthopedic center in South India. Of the total 141 patients with Gram-negative bacteremia, 44 had carbapenem resistant ones. Of these 44 patients, 17 were neutropenics (resistant neutropenic group) and 27 nonneutropenic patients (resistant nonneutropenic group). Of the 97 patients with carbapenem sensitive bacteremia, 43 were neutropenic (sensitive neutropenic group) and 54 nonneutropenics (sensitive nonneutropenic group). The 28 days mortality was significantly higher in carbapenem resistant bacteremic group compared to the sensitive one (P = 0.008). This is the first study from India comparing clinical features of patients with carbapenem sensitive and resistant blood stream infections. Patients with carbapenem resistant bacteremia had higher mortality compared to patients with sensitive bacteremia.

  2. Rectal carriage of extended-spectrum beta-lactamase-producing gram-negative bacilli in community settings in Madagascar.

    Directory of Open Access Journals (Sweden)

    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.

  3. Recurrent upper airway infections and bacterial biofilms.

    Science.gov (United States)

    Galli, J; Ardito, F; Calò, L; Mancinelli, L; Imperiali, M; Parrilla, C; Picciotti, P M; Fadda, G

    2007-04-01

    Bacterial biofilms identified in various medical devices used in otorhinolaryngology, including tympanostomy tubes, voice prostheses, and cochlear implants, can directly colonise mucosal tissues. The upper airways seem to be at high risk for this type of colonisation. Chronic and/or recurrent upper airway infections may be related to the complex structural and biochemical (quorum sensing) organisation of the biofilm which interferes with the activity of antibiotics (including those with proven in vitro efficacy), thus promoting the establishment of a chronic infection eradicable only by surgical treatment. Biofilm formation plays a role in upper respiratory infections: it not only explains the resistance of these infections to antibiotic therapy but it also represents an important element that contributes to the maintenance of a chronic inflammatory reaction. To document the presence of biofilms in surgical tissue specimens from patients with recurrent infection diseases, and identify their possible role in the chronicity of these infectious processes. We examined 32 surgical specimens from the upper respiratory tract (tonsils, adenoids, mucosa from the ethmoid and maxillary sinuses) of 28 patients (20 adults, eight children) with upper airway infections that had persisted despite repeated treatment with anti-inflammatory agents and antibiotics with demonstrated in vitro efficacy. Tissues were cultured using conventional methods and subjected to scanning electron microscopy for detection of biofilm formation. Over 80 per cent (26/32; 81.3 per cent) of the tissue specimens were culture-positive. Bacterial biofilms (associated in most cases with coccoid bacteria) were observed in 65.6 per cent of the tissue samples.

  4. Host and bacterial proteins that repress recruitment of LC3 to Shigella early during infection.

    Directory of Open Access Journals (Sweden)

    Leigh A Baxt

    Full Text Available Shigella spp. are intracytosolic gram-negative pathogens that cause disease by invasion and spread through the colonic mucosa, utilizing host cytoskeletal components to form propulsive actin tails. We have previously identified the host factor Toca-1 as being recruited to intracellular S. flexneri and being required for efficient bacterial actin tail formation. We show that at early times during infection (40 min., the type three-secreted effector protein IcsB recruits Toca-1 to intracellular bacteria and that recruitment of Toca-1 is associated with repression of recruitment of LC3, as well as with repression of recruitment of the autophagy marker NDP52, around these intracellular bacteria. LC3 is best characterized as a marker of autophagosomes, but also marks phagosomal membranes in the process LC3-associated phagocytosis. IcsB has previously been demonstrated to be required for S. flexneri evasion of autophagy at late times during infection (4-6 hr by inhibiting binding of the autophagy protein Atg5 to the Shigella surface protein IcsA (VirG. Our results suggest that IcsB and Toca-1 modulation of LC3 recruitment restricts LC3-associated phagocytosis and/or LC3 recruitment to vacuolar membrane remnants. Together with published results, our findings suggest that IcsB inhibits innate immune responses in two distinct ways, first, by inhibiting LC3-associated phagocytosis and/or LC3 recruitment to vacuolar membrane remnants early during infection, and second, by inhibiting autophagy late during infection.

  5. 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

  6. The effect of N-formimidoyl thienamycin, ceftazidime, cefotiam, ceftriaxone and cefotaxime on non-fermentative Gram-negative rods, Aeromonas, Plesiomonas and Enterobacter agglomerans.

    Science.gov (United States)

    von Graevenitz, A; Bucher, C

    1982-01-01

    Thirty-one species (185 strains) of non-fermentative gram-negative rods (excluding Pseudomonas aeruginosa) as well as 45 strains of Aeromonas spp., 15 strains of Plesiomonas shigelloides and 68 strains of Enterobacter agglomerans were tested in microdilution procedures against N-formimidoyl thienamycin, ceftazidime, cefotiam, ceftriaxone and cefotaxime. N-formimidoyl thienamycin was the most effective drug as far as the spectrum of these bacterial groups and potency is concerned; ceftazidime was the second most effective agent. Ceftriaxone and cefotaxime were similar in their activity (against a smaller spectrum), while cefotiam showed little effect. There were occasional differences between MBC and MIC values which were most notable with ceftazidime, cefotiam, ceftriaxone and cefotaxime against E. agglomerans.

  7. 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.

  8. 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

  9. 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

  10. 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...

  11. 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.

  12. Complete Genome Sequence of Bacillus velezensis CN026 Exhibiting Antagonistic Activity against Gram-Negative Foodborne Pathogens.

    Science.gov (United States)

    Nannan, Catherine; Gillis, Annika; Caulier, Simon; Mahillon, Jacques

    2018-01-25

    We report here the complete genome sequence of Bacillus velezensis strain CN026, a member of the B. subtilis group, which is known for its many industrial applications. The genome contains 3,995,812 bp and displays six gene clusters potentially involved in strain CN026's activity against Gram-negative foodborne pathogens. Copyright © 2018 Nannan et al.

  13. Complete Genome Sequence of Bacillus velezensis CN026 Exhibiting Antagonistic Activity against Gram-Negative Foodborne Pathogens

    OpenAIRE

    Nannan, Catherine; Gillis, Annika; Caulier, Simon; Mahillon, Jacques

    2018-01-01

    ABSTRACT We report here the complete genome sequence of Bacillus velezensis strain CN026, a member of the B. subtilis group, which is known for its many industrial applications. The genome contains 3,995,812 bp and displays six gene clusters potentially involved in strain CN026’s activity against Gram-negative foodborne pathogens.

  14. In vitro Efficacy of Meropenem, Colistin and Tigecycline Against the Extended Spectrum Beta-Lactamase Producing Gram Negative Bacilli

    International Nuclear Information System (INIS)

    Gill, M. M.; Usman, J.; Hassan, A.; Kaleem, F.; Anjum, R.

    2015-01-01

    Objective:To compare the in vitroefficacy of meropenem, colistin and tigecycline against extended spectrum Betalactamase producing Gram negative bacilli by minimal inhibitory concentration. Study Design:Cross-sectional descriptive study. Place and Duration of Study: Department of Microbiology, Army Medical College, National University of Sciences and Technology, Rawalpindi, from June to December 2010. Methodology: Routine clinical specimens were subjected to standard microbiological procedures and the isolates were identified to species level. Extended spectrum beta-lactamase producing Gram negative bacilli were detected by Jarlier disc synergy method and confirmed by ceftazidime and ceftazidime-clavulanate Etest. Minimum Inhibitory Concentration (MIC90) of meropenem, colistin and tigecycline was determined by Etest (AB BIOMERIUX) and the results were interpreted according to the manufacturer's instructions and Clinical and Laboratory Standards Institute guidelines and Food and Drug Authority recommendations. Results were analyzed by using Statistical Package for the Social Sciences version 20. Results: A total of 52 non-duplicate extended spectrum Beta-lactamase-producing Gram negative bacilli were included in the study. The MIC90 of tigecycline (0.75 micro g/ml) was lowest as compared to the meropenem (2 micro g/ml) and colistin (3 micro g/ml). Conclusion: Tigecycline is superior in efficacy against the extended spectrum Beta-lactamase producing Gram negative bacilli as compared to colistin and meropenem. (author)

  15. Prevalence of Extended Spectrum β-Lactamase, AmpC β-Lactamase and Metallo-β-Lactamase Among Gram Negative Bacilli Recovered From Clinical Specimens in Benin City, Nigeria

    Directory of Open Access Journals (Sweden)

    Ephraim Ehidiamen Ibadin

    2017-08-01

    Full Text Available Background: Multidrug resistant bacteria continue to be a bane in the treatment of clinical infections in Nigeria. Knowledge of trends in resistance mechanisms is vital in determining available therapeutic options. Objective: This study was aimed at determining the prevalence, distribution and antimicrobial susceptibility of extended spectrum β-lactamase (ESBL, AmpC β-lactamase and metallo-β-lactamase (MBL-producing gram negative bacteria (GNB recovered from clinical specimens in a tertiary hospital in Southern Nigeria. Materials and Methods: A total of 309 consecutive non-repetitive clinical bacterial isolates were recovered from various clinical specimens. The presence of ESBL, AmpC β-lactamase and MBL as well as the susceptibility profiles were determined using standard microbiological techniques. Results: ESBL was the most prevalent (P < 0.0001 of the 3 enzymes detected in this study. Bacterial isolates recovered from inpatients had a higher likelihood of producing ESBL than those recovered from out-patients (odds ratio [OR] = 2.225, 95% CI = 1.375, 3.599; P = 0.0015. The highest prevalence of ESBL, AmpC and MBL enzyme was observed for Providencia species, Pseudomonas aeruginosa and Citrobacter species respectively. β-Lactamase positive isolates showed poor activity against cephalosporin, amoxicillin-clavulanate, gentamicin and the fluoroquinolones. Isolates that produced any of the three β-lactamase enzymes showed more resistance to antibacterial drugs than β-lactamase negative bacterial isolates. Conclusion: A prevalence of 41.7%, 15.2% and 28.5% was observed for ESBL, AmpC β-lactamase and MBL respectively in this study. Isolates that produced any of the enzymes were more resistant to antibacterial agents. Prudence in antibiotic use is strongly advocated.

  16. 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

  17. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. 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.

  20. β-lactam resistance in gram-negative pathogens isolated from animals.

    Science.gov (United States)

    Trott, Darren

    2013-01-01

    Although β-lactams remain a cornerstone of veterinary therapeutics, only a restricted number are actually approved for use in food-producing livestock in comparison to companion animals and wildlife. Nevertheless, both registered and off-label use of third and fourth-generation cephalosporins in livestock may have influenced the emergence of plasmid-encoded AmpC β-lactamases (pAmpC) (mainly CMY-2) and CTX-M extended-spectrum β-lactamases (ESBLs) in both Gram-negative pathogens and commensals isolated from animals. This presents a public health concern due to the potential risk of transfer of β-lactam-resistant pathogens from livestock to humans through food. The recent detection of pAmpC and ESBLs in multidrug-resistant Enterobacteriaceae isolated from dogs has also confirmed the public health importance of β-lactam resistance in companion animals, though in this case, human-to-animal transmission may be equally as relevant as animal-to-human transmission. Identification of pAmpC and ESBLs in Enterobacteriaceae isolated from wildlife and aquaculture species may be evidence of environmental selection pressure arising from both human and veterinary use of β- lactams. Such selection pressure in animals could be reduced by the availability of reliable alternative control measures such as vaccines, bacteriophage treatments and/or competitive exclusion models for endemic production animal diseases such as colibacillosis. The global emergence and pandemic spread of extraintestinal pathogenic E. coli O25-ST131 strains expressing CTX-M-15 ESBL in humans and its recent detection in livestock, companion animals and wildlife is a major cause for concern and goes against the paradigm that Gramnegative pathogens do not necessarily have to lose virulence in compensation for acquiring resistance.

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

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    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.

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. Targeted imaging of bacterial infections : advances, hurdles and hopes

    NARCIS (Netherlands)

    van Oosten, Marleen; Hahn, Markus; Crane, Lucia M. A.; Pleijhuis, Rick G.; Francis, Kevin P.; van Dijl, Jan Maarten; van Dam, Gooitzen M.

    2015-01-01

    Bacterial infections represent an increasing problem in modern health care, in particular due to ageing populations and accumulating bacterial resistance to antibiotics. Diagnosis is rarely straightforward and consequently treatment is often delayed or indefinite. Therefore, novel tools that can be

  7. The Typhoid Toxin Promotes Host Survival and the Establishment of a Persistent Asymptomatic Infection

    DEFF Research Database (Denmark)

    Del Bel Belluz, Lisa; Guidi, Riccardo; Pateras, Ioannis S.

    2016-01-01

    Bacterial genotoxins, produced by several Gram-negative bacteria, induce DNA damage in the target cells. While the responses induced in the host cells have been extensively studied in vitro, the role of these effectors during the course of infection remains poorly characterized. To address this i...

  8. Extraction and partial characterization of a leukotoxin from a plaque-derived Gram-negative microorganism.

    Science.gov (United States)

    Tsai, C C; McArthur, W P; Baehni, P C; Hammond, B F; Taichman, N S

    1979-01-01

    The plaque-derived gram-negative microorganism Y4 identified as a member of the genus Actinobacillus, was tested for a soluble cytotoxic factor(s). Sonication or incubation of viable Y4 microorganisms in distilled water or normal human serum resulted in liberation of a soluble material which was cytotoxic in vitro for human polymorphonuclear leukocytes (PMNs). The Y4 soluble sonic extract was also cytotoxic to human peripheral blood monocytes. However, human lymphocytes, platelets, and fibroblasts, as well as rabbit, rat, and mouse leukocytes and chicken embryo fibroblasts, were not killed by exposure to the Y4 sonic extract. No hemolytic activity was detected in the Y4 sonic extract. No hemolytic activity was detected in the Y4 sonic extract. Consequently, the factor(s) in the Y4 sonic extract was referred to as Y4 leukotoxin. The Y4 leukotoxin was inactive at 4 degrees C, heat sensitive (56 degrees C, 30 min), and inactivated by proteases. The cytotoxic effect of Y4 leukotoxin on PMNs was dose, time, and temperature dependent. The leukotoxin did not bind to viable PMNs at 4 degrees C but did bind to dead PMN membrane components at both 4 and 37 degrees C. The addition of bovine serum albumin (51 mg/ml) to PMN-Y4 leukotoxin cultures inhibited the release of lactate dehydrogenase from the PMNs, but did not prevent the death of the cells as indicated by electron microscopy. Lysosomal markers were released in parallel to the cytoplasmic enzyme lactate dehydrogenase from Y4 leukotoxin-treated PMNs. The addition of 0.02 M ethylenedinitrilotetraacetic acid to these cultures inhibited release of lysosomal markers but enhanced the release of lactate dehydrogenase. These results suggested that a soluble leukotoxin with specificity for only human PMNs and monocytes can be liberated from viable Y4. What role this leukotoxin plays in the pathogenicity of the Y4 microorganism is not yet known. However, this leukotoxin is one of the first materials from a plaque

  9. Organization and Biology of the Porcine Serum Amyloid A (SAA) Gene Cluster: Isoform Specific Responses to Bacterial Infection

    DEFF Research Database (Denmark)

    Olsen, Helle G; Skovgaard, Kerstin; Nielsen, Ole L

    2013-01-01

    expression of porcine SAA1, SAA2, SAA3, and SAA4 by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) in liver, spleen, and lung tissue from pigs experimentally infected with the Gram-negative swine specific bacterium Actinobacillus pleuropneumoniae, as well as from pigs experimentally...

  10. 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.

  11. Comparison of the Cathra Repliscan II, the AutoMicrobic system Gram-Negative General Susceptibility-Plus Card, and the Micro-Media System Fox Panel for dilution susceptibility testing of gram-negative bacilli.

    Science.gov (United States)

    Reiber, N E; Kelly, M T; Latimer, J M; Tison, D L; Hysmith, R M

    1985-06-01

    A comparative evaluation was done to test the accuracy of the Cathra Repliscan II agar dilution system (Diagnostic Equipment, Inc., St. Paul, Minn.), the AutoMicrobic system with Gram-Negative General Susceptibility-Plus Card (Vitek Systems, Inc., Hazelwood, Mo.), and the Micro-Media Fox Panel micro broth dilution system (Micro-Media Systems, Inc., San Jose, Calif.) in determining MICs of 12 antibiotics for 200 gram-negative bacilli. Of the 200 strains tested, 12 isolates did not grow in one of the three systems. The 188 remaining organisms included 158 members of the family Enterobacteriaceae, 20 Pseudomonas spp., 5 Acinetobacter sp., 3 Aeromonas spp., and 2 Vibrio spp. A total of 2,256 organism-antibiotic combinations were analyzed for each system. An MIC was considered correct if two of the three systems were in agreement. When disagreements occurred, correct MICs were determined by the standard agar dilution method. With this criterion, overall agreements of the Cathra Repliscan II system, AutoMicrobic system, and Micro-Media Fox Panel system were 94.7, 94.9, and 95.5%, respectively. Tetracycline (20%), nitrofurantoin (20%), and ampicillin (16%) accounted for 56% of the discrepancies observed. These results indicate that all three systems perform with a high degree of accuracy for susceptibility testing of gram-negative bacilli.

  12. Bacterial Infections Following Splenectomy for Malignant and Nonmalignant Hematologic Diseases

    Science.gov (United States)

    Leone, Giuseppe; Pizzigallo, Eligio

    2015-01-01

    Splenectomy, while often necessary in otherwise healthy patients after major trauma, finds its primary indication for patients with underlying malignant or nonmalignant hematologic diseases. Indications of splenectomy for hematologic diseases have been reducing in the last few years, due to improved diagnostic and therapeutic tools. In high-income countries, there is a clear decrease over calendar time in the incidence of all indication splenectomy except nonmalignant hematologic diseases. However, splenectomy, even if with different modalities including laparoscopic splenectomy and partial splenectomy, continue to be a current surgical practice both in nonmalignant hematologic diseases, such as Immune Thrombocytopenic Purpura (ITP), Autoimmune Hemolytic Anemia (AIHA), Congenital Hemolytic Anemia such as Spherocytosis, Sickle Cell Anemia and Thalassemia and Malignant Hematological Disease, such as lymphoma. Today millions of people in the world are splenectomized. Splenectomy, independently of its cause, induces an early and late increase in the incidence of venous thromboembolism and infections. Infections remain the most dangerous complication of splenectomy. After splenectomy, the levels of antibody are preserved but there is a loss of memory B cells against pneumococcus and tetanus, and the loss of marginal zone monocytes deputed to immunological defense from capsulated bacteria. Commonly, the infections strictly correlated to the absence of the spleen or a decreased or absent spleni