Dielectrophoretic assay of bacterial resistance to antibiotics

International Nuclear Information System (INIS)

Johari, Juliana; Huebner, Yvonne; Hull, Judith C; Dale, Jeremy W; Hughes, Michael P

2003-01-01

The dielectrophoretic collection spectra of antibiotic-sensitive and antibiotic-resistant strains of Staphylococcus epidermidis have been determined. These indicate that in the absence of antibiotic treatment there is a strong similarity between the dielectric properties of sensitive and resistant strains, and that there is a significant difference between the sensitive strains before and after treatment with the antibiotic streptomycin after 24 h exposure. This method offers possibilities for the assessment of bacterial resistance to antibiotics. (note)

Bacterial Cheating Limits the Evolution of Antibiotic Resistance

Science.gov (United States)

Yurtsev, Eugene; Xiao Chao, Hui; Datta, Manoshi; Artemova, Tatiana; Gore, Jeff

2012-02-01

The emergence of antibiotic resistance in bacteria is a significant health concern. Bacteria can gain resistance to the antibiotic ampicillin by acquiring a plasmid carrying the gene beta-lactamase, which inactivates the antibiotic. This inactivation may represent a cooperative behavior, as the entire bacterial population benefits from removal of the antibiotic. The presence of a cooperative mechanism of resistance suggests that a cheater strain - which does not contribute to breaking down the antibiotic - may be able to take advantage of resistant cells. We find experimentally that a ``sensitive'' bacterial strain lacking the plasmid conferring resistance can invade a population of resistant bacteria, even in antibiotic concentrations that should kill the sensitive strain. We use a simple model in conjunction with difference equations to explain the observed population dynamics as a function of cell density and antibiotic concentration. Our experimental difference equations resemble the logistic map, raising the possibility of oscillations or even chaotic dynamics.

Antibiotic resistance

Directory of Open Access Journals (Sweden)

Marianne Frieri

2017-07-01

Full Text Available Summary: Antimicrobial resistance in bacterial pathogens is a challenge that is associated with high morbidity and mortality. Multidrug resistance patterns in Gram-positive and -negative bacteria are difficult to treat and may even be untreatable with conventional antibiotics. There is currently a shortage of effective therapies, lack of successful prevention measures, and only a few new antibiotics, which require development of novel treatment options and alternative antimicrobial therapies. Biofilms are involved in multidrug resistance and can present challenges for infection control. Virulence, Staphylococcus aureus, Clostridium difficile infection, vancomycin-resistant enterococci, and control in the Emergency Department are also discussed. Keywords: Antibiotic resistance, Biofilms, Infections, Public health, Emergency Department

Bacterial Aetiology and Antibiotic Resistance Pattern of Community-Acquired Urinary Tract Infections in Children in a Tertiary Care Hospital in Bangladesh

Directory of Open Access Journals (Sweden)

Lazina Sharmin

2017-09-01

Full Text Available Background: Urinary tract infections (UTIs in children are among the most common bacterial infections. Community-acquired urinary tract infections (CAUTI are often treated empirically with broad-spectrum antibiotics. Pattern of aetiologic agents and their antibiotic sensitivity may vary according to geographical and regional location. So, knowledge of antibiotic resistance trends is important for improving evidence-based recommendations for empirical treatment of UTIs. Objectives: To determine the common bacterial aetiologies of CAUTIs and their antibiotic resistance patterns in a tertiary care hospital, Savar. Materials and Methods: This cross-sectional descriptive study was conducted at Enam Medical College Hospital, Savar from May 2016 to April 2017. We collected clean-catch mid-stream urine samples from 257 patients having clinical diagnosis of UTI and submitted to the clinical microbiology laboratory for culture and sensitivity. Results: A total of 120 (46.7% samples were positive for bacterial growth. Escherichia coli (79% was the most common pathogen, followed by Klebsiella spp. (14%. Bacterial isolates showed high prevalence of resistance to multiple antibiotics. Resistance against amoxicillin/clavulanic acid, co-trimoxazole and ciprofloxacin was higher compared to newer quinolones and aminoglycosides. Conclusion: Esch. coli and Klebsiella spp. were the predominant bacterial pathogens. The resistance pattern to commonly prescribed antibiotics was quite high and alarming.

Bacterial Etiology and Antibiotic Resistance Profile of Community-Acquired Urinary Tract Infections in a Cameroonian City.

Science.gov (United States)

Nzalie, Rolf Nyah-Tuku; Gonsu, Hortense Kamga; Koulla-Shiro, Sinata

2016-01-01

Introduction. Community-acquired urinary tract infections (CAUTIs) are usually treated empirically. Geographical variations in etiologic agents and their antibiotic sensitivity patterns are common. Knowledge of antibiotic resistance trends is important for improving evidence-based recommendations for empirical treatment of UTIs. Our aim was to determine the major bacterial etiologies of CAUTIs and their antibiotic resistance patterns in a cosmopolitan area of Cameroon for comparison with prescription practices of local physicians. Methods. We performed a cross-sectional descriptive study at two main hospitals in Yaoundé, collecting a clean-catch mid-stream urine sample from 92 patients having a clinical diagnosis of UTI. The empirical antibiotherapy was noted, and identification of bacterial species was done on CLED agar; antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method. Results. A total of 55 patients had samples positive for a UTI. Ciprofloxacin and amoxicillin/clavulanic acid were the most empirically prescribed antibiotics (30.9% and 23.6%, resp.); bacterial isolates showed high prevalence of resistance to both compounds. Escherichia coli (50.9%) was the most common pathogen, followed by Klebsiella pneumoniae (16.4%). Prevalence of resistance for ciprofloxacin was higher compared to newer quinolones. Conclusions. E. coli and K. pneumoniae were the predominant bacterial etiologies; the prevalence of resistance to commonly prescribed antibiotics was high.

Bacterial Contamination of Iranian Paper Currency and Their Antibiotic Resistance Patterns

Directory of Open Access Journals (Sweden)

Farzaneh Firoozeh

2017-11-01

Full Text Available Background: Paper currency is used in exchange for services, and thisis why the circulation of paper currency from person to person expandsmicroorganisms. Objectives:: Paper banknotes would be a vector for transmission of pathogenic microorganisms through handling. This study aimed to determine bacterial contamination of Iranian paper currencies in circulation and their antibiotic resistance patterns. Materials and Methods: In this study, 337 currency notes of different value were collected from markets, shops, restaurants, bus stations and banks in Kashan, Iran during April 2015 to March 2016. The currency notes transferred to microbiology laboratory and were tested for bacterial contamination using standard microbiological methods. Antibiotic resistance patterns of isolated bacteria were determined by disk diffusion method according to CLSI standards. The results and data were analyzed using descriptive statistics. Results: Of 337 currency notes, 262 (77.7% were identified with bacterial contamination. Bacteria isolated from currency notes were as follows: Bacillus spp 113 (43.1%, coagulase-negative Staphylococci 99 (37.7%, Escherichia coli 20 (7.6%, Enterococci species 14 (5.3%, Staphylococcus aureus 8 (3.1%, Klebsiella spp 4 (1.5%, Shigella species 2 (0.8%, Pseudomonas species 2 (0.8%. The most and least contaminated currency notes were 50000 and 500 Rials, respectively. The most resistance rates in gram negative rods were against nalidixicacid, and ampicillin. Also most resistance rates in Staphylococcus aureus, coagulase-negative Staphylococci and Enterococci species were against ampicillin, erythromycin and tetracycline. Conclusion: Our study revealed that the bacterial contamination among Iranian paper currency in circulation especially those obtained from certain sources including shops and bus stations is high and in most cases these bacterial isolates are antibiotic resistant strains.

The causes and consequences of antibiotic resistance evolution in microbial pathogens

DEFF Research Database (Denmark)

Jochumsen, Nicholas

pleiotropy as they conferred a decreased growth rate in the absence of colistin and also rendered the colistin resistant strains susceptible towards all tested classes of β-lactams. The results suggest that colistin/β-lactam combination therapy could be used to reduce the risk of resistance evolution during......The evolution of antimicrobial resistance in bacterial pathogens is a growing global health problem that is gradually making the successful treatment of infectious diseases more difficult. Antimicrobial peptides have been proposed as promising candidates for future drug development as they retain...... activity against bacteria resistant to conventional antibiotics and because resistance evolution is expected to be unlikely since the peptides have complex modes of action due to their interaction with the bacterial membrane. The work presented in this thesis has involved studies to increase our...

Sequence-Specific Targeting of Bacterial Resistance Genes Increases Antibiotic Efficacy

Science.gov (United States)

Wong, Michael; Daly, Seth M.; Greenberg, David E.; Toprak, Erdal

2016-01-01

The lack of effective and well-tolerated therapies against antibiotic-resistant bacteria is a global public health problem leading to prolonged treatment and increased mortality. To improve the efficacy of existing antibiotic compounds, we introduce a new method for strategically inducing antibiotic hypersensitivity in pathogenic bacteria. Following the systematic verification that the AcrAB-TolC efflux system is one of the major determinants of the intrinsic antibiotic resistance levels in Escherichia coli, we have developed a short antisense oligomer designed to inhibit the expression of acrA and increase antibiotic susceptibility in E. coli. By employing this strategy, we can inhibit E. coli growth using 2- to 40-fold lower antibiotic doses, depending on the antibiotic compound utilized. The sensitizing effect of the antisense oligomer is highly specific to the targeted gene’s sequence, which is conserved in several bacterial genera, and the oligomer does not have any detectable toxicity against human cells. Finally, we demonstrate that antisense oligomers improve the efficacy of antibiotic combinations, allowing the combined use of even antagonistic antibiotic pairs that are typically not favored due to their reduced activities. PMID:27631336

Consolidating and Exploring Antibiotic Resistance Gene Data Resources

DEFF Research Database (Denmark)

Xavier, Basil Britto; Das, Anupam J.; Cochrane, Guy

2016-01-01

The unrestricted use of antibiotics has resulted in rapid acquisition of antibiotic resistance (AR) and spread of multidrug-resistant (MDR) bacterial pathogens. With the advent of next-generation sequencing technologies and their application in understanding MDR pathogen dynamics, it has become i...

[Virulence and its relationship to antibiotic resistance].

Science.gov (United States)

Joly-Guillou, M L

1998-12-01

PATHOGENIC ISLANDS: Certain DNA blocks inserted into the chromosome of most Gram negative bacteria originated in pathogens found in plants. VIRULENCE-ANTIBIOTIC INTERACTIONS: During the invasive phase, the bacterial cell covers itself with adhesins which facilitate its adherence to tissues. The bacterial cell produces a fibronectin which protects its defense systems. Antibiotics favor bacterial resistance by increasing the expression of surface adhesins and fibronectin production. PENICILLIN RESISTANT PNEUMOCOCCI: Experimental models have demonstrated that mortality in mice and host resistance to pneumococcal infection are related to the type of capsule and not to antibiotic resistance. QUORUM SENSING: The bacterial inoculum regulates the production of virulence factors in vivo via quorum sensing. This regulation can play an important role in Pseudomonas aeruginosa infections. ACINETOBACTER BAUMANNI VIRULENCE: Long poorly understood, factors favoring A. baumanni virulence appear to result from bacterial production of IROMPs in the extracellular growth medium in response to iron depletion during the exponential growth phase.

Sensitizing pathogens to antibiotics using the CRISPR-Cas system.

Science.gov (United States)

Goren, Moran; Yosef, Ido; Qimron, Udi

2017-01-01

The extensive use of antibiotics over the last century has resulted in a significant artificial selection pressure for antibiotic-resistant pathogens to evolve. Various strategies to fight these pathogens have been introduced including new antibiotics, naturally-derived enzymes/peptides that specifically target pathogens and bacteriophages that lyse these pathogens. A new tool has recently been introduced in the fight against drug-resistant pathogens-the prokaryotic defense mechanism-clustered regularly interspaced short palindromic repeats-CRISPR associated (CRISPR-Cas) system. The CRISPR-Cas system acts as a nuclease that can be guided to cleave any target DNA, allowing sophisticated, yet feasible, manipulations of pathogens. Here, we review pioneering studies that use the CRISPR-Cas system to specifically edit bacterial populations, eliminate their resistance genes and combine these two strategies in order to produce an artificial selection pressure for antibiotic-sensitive pathogens. We suggest that intelligent design of this system, along with efficient delivery tools into pathogens, may significantly reduce the threat of antibiotic-resistant pathogens. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bacterial Etiology and Antibiotic Resistance Profile of Community-Acquired Urinary Tract Infections in a Cameroonian City

Directory of Open Access Journals (Sweden)

Rolf Nyah-tuku Nzalie

2016-01-01

Full Text Available Introduction. Community-acquired urinary tract infections (CAUTIs are usually treated empirically. Geographical variations in etiologic agents and their antibiotic sensitivity patterns are common. Knowledge of antibiotic resistance trends is important for improving evidence-based recommendations for empirical treatment of UTIs. Our aim was to determine the major bacterial etiologies of CAUTIs and their antibiotic resistance patterns in a cosmopolitan area of Cameroon for comparison with prescription practices of local physicians. Methods. We performed a cross-sectional descriptive study at two main hospitals in Yaoundé, collecting a clean-catch mid-stream urine sample from 92 patients having a clinical diagnosis of UTI. The empirical antibiotherapy was noted, and identification of bacterial species was done on CLED agar; antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method. Results. A total of 55 patients had samples positive for a UTI. Ciprofloxacin and amoxicillin/clavulanic acid were the most empirically prescribed antibiotics (30.9% and 23.6%, resp.; bacterial isolates showed high prevalence of resistance to both compounds. Escherichia coli (50.9% was the most common pathogen, followed by Klebsiella pneumoniae (16.4%. Prevalence of resistance for ciprofloxacin was higher compared to newer quinolones. Conclusions. E. coli and K. pneumoniae were the predominant bacterial etiologies; the prevalence of resistance to commonly prescribed antibiotics was high.

Phenotypic Resistance to Antibiotics

Directory of Open Access Journals (Sweden)

Jose L. Martinez

2013-04-01

Full Text Available The development of antibiotic resistance is usually associated with genetic changes, either to the acquisition of resistance genes, or to mutations in elements relevant for the activity of the antibiotic. However, in some situations resistance can be achieved without any genetic alteration; this is called phenotypic resistance. Non-inherited resistance is associated to specific processes such as growth in biofilms, a stationary growth phase or persistence. These situations might occur during infection but they are not usually considered in classical susceptibility tests at the clinical microbiology laboratories. Recent work has also shown that the susceptibility to antibiotics is highly dependent on the bacterial metabolism and that global metabolic regulators can modulate this phenotype. This modulation includes situations in which bacteria can be more resistant or more susceptible to antibiotics. Understanding these processes will thus help in establishing novel therapeutic approaches based on the actual susceptibility shown by bacteria during infection, which might differ from that determined in the laboratory. In this review, we discuss different examples of phenotypic resistance and the mechanisms that regulate the crosstalk between bacterial metabolism and the susceptibility to antibiotics. Finally, information on strategies currently under development for diminishing the phenotypic resistance to antibiotics of bacterial pathogens is presented.

Antibiotic Resistance in Human Chronic Periodontitis Microbiota

NARCIS (Netherlands)

Rams, Thomas E.; Degener, John E.; van Winkelhoff, Arie J.

Background: Patients with chronic periodontitis (CP) may yield multiple species of putative periodontal bacterial pathogens that vary in their antibiotic drug susceptibility. This study determines the occurrence of in vitro antibiotic resistance among selected subgingival periodontal pathogens in

The neglected intrinsic resistome of bacterial pathogens.

Directory of Open Access Journals (Sweden)

Alicia Fajardo

Full Text Available Bacteria with intrinsic resistance to antibiotics are a worrisome health problem. It is widely believed that intrinsic antibiotic resistance of bacterial pathogens is mainly the consequence of cellular impermeability and activity of efflux pumps. However, the analysis of transposon-tagged Pseudomonas aeruginosa mutants presented in this article shows that this phenotype emerges from the action of numerous proteins from all functional categories. Mutations in some genes make P. aeruginosa more susceptible to antibiotics and thereby represent new targets. Mutations in other genes make P. aeruginosa more resistant and therefore define novel mechanisms for mutation-driven acquisition of antibiotic resistance, opening a new research field based in the prediction of resistance before it emerges in clinical environments. Antibiotics are not just weapons against bacterial competitors, but also natural signalling molecules. Our results demonstrate that antibiotic resistance genes are not merely protective shields and offer a more comprehensive view of the role of antibiotic resistance genes in the clinic and in nature.

Isolation of antibiotic-resistant pathogenic and potentially ...

African Journals Online (AJOL)

2010-09-13

Sep 13, 2010 ... The aim of the present study is to determine the pathogenic and potentially ... Keywords: pathogenic bacteria; antibiotic resistance; carpets; mosques; Tripoli; Libya .... During the process of praying, a Muslim is obliged to go.

Synergistic antimicrobial therapy using nanoparticles and antibiotics for the treatment of multidrug-resistant bacterial infection

Science.gov (United States)

Gupta, Akash; Saleh, Neveen M.; Das, Riddha; Landis, Ryan F.; Bigdeli, Arafeh; Motamedchaboki, Khatereh; Rosa Campos, Alexandre; Pomeroy, Kenneth; Mahmoudi, Morteza; Rotello, Vincent M.

2017-06-01

Infections caused by multidrug-resistant (MDR) bacteria pose a serious global burden of mortality, causing thousands of deaths each year. Antibiotic treatment of resistant infections further contributes to the rapidly increasing number of antibiotic-resistant species and strains. Synthetic macromolecules such as nanoparticles (NPs) exhibit broad-spectrum activity against MDR species, however lack of specificity towards bacteria relative to their mammalian hosts limits their widespread therapeutic application. Here, we demonstrate synergistic antimicrobial therapy using hydrophobically functionalized NPs and fluoroquinolone antibiotics for treatment of MDR bacterial strains. An 8-16-fold decrease in antibiotic dosage is achieved in presence of engineered NPs to combat MDR strains. This strategy demonstrates the potential of using NPs to ‘revive’ antibiotics that have been rendered ineffective due to the development of resistance by pathogenic bacteria.

Genomic Microbial Epidemiology Is Needed to Comprehend the Global Problem of Antibiotic Resistance and to Improve Pathogen Diagnosis.

Science.gov (United States)

Wyrsch, Ethan R; Roy Chowdhury, Piklu; Chapman, Toni A; Charles, Ian G; Hammond, Jeffrey M; Djordjevic, Steven P

2016-01-01

Contamination of waste effluent from hospitals and intensive food animal production with antimicrobial residues is an immense global problem. Antimicrobial residues exert selection pressures that influence the acquisition of antimicrobial resistance and virulence genes in diverse microbial populations. Despite these concerns there is only a limited understanding of how antimicrobial residues contribute to the global problem of antimicrobial resistance. Furthermore, rapid detection of emerging bacterial pathogens and strains with resistance to more than one antibiotic class remains a challenge. A comprehensive, sequence-based genomic epidemiological surveillance model that captures essential microbial metadata is needed, both to improve surveillance for antimicrobial resistance and to monitor pathogen evolution. Escherichia coli is an important pathogen causing both intestinal [intestinal pathogenic E. coli (IPEC)] and extraintestinal [extraintestinal pathogenic E. coli (ExPEC)] disease in humans and food animals. ExPEC are the most frequently isolated Gram negative pathogen affecting human health, linked to food production practices and are often resistant to multiple antibiotics. Cattle are a known reservoir of IPEC but they are not recognized as a source of ExPEC that impact human or animal health. In contrast, poultry are a recognized source of multiple antibiotic resistant ExPEC, while swine have received comparatively less attention in this regard. Here, we review what is known about ExPEC in swine and how pig production contributes to the problem of antibiotic resistance.

Alternative Evolutionary Paths to Bacterial Antibiotic Resistance Cause Distinct Collateral Effects.

Science.gov (United States)

Barbosa, Camilo; Trebosc, Vincent; Kemmer, Christian; Rosenstiel, Philip; Beardmore, Robert; Schulenburg, Hinrich; Jansen, Gunther

2017-09-01

When bacteria evolve resistance against a particular antibiotic, they may simultaneously gain increased sensitivity against a second one. Such collateral sensitivity may be exploited to develop novel, sustainable antibiotic treatment strategies aimed at containing the current, dramatic spread of drug resistance. To date, the presence and molecular basis of collateral sensitivity has only been studied in few bacterial species and is unknown for opportunistic human pathogens such as Pseudomonas aeruginosa. In the present study, we assessed patterns of collateral effects by experimentally evolving 160 independent populations of P. aeruginosa to high levels of resistance against eight commonly used antibiotics. The bacteria evolved resistance rapidly and expressed both collateral sensitivity and cross-resistance. The pattern of such collateral effects differed to those previously reported for other bacterial species, suggesting interspecific differences in the underlying evolutionary trade-offs. Intriguingly, we also identified contrasting patterns of collateral sensitivity and cross-resistance among the replicate populations adapted to the same drug. Whole-genome sequencing of 81 independently evolved populations revealed distinct evolutionary paths of resistance to the selective drug, which determined whether bacteria became cross-resistant or collaterally sensitive towards others. Based on genomic and functional genetic analysis, we demonstrate that collateral sensitivity can result from resistance mutations in regulatory genes such as nalC or mexZ, which mediate aminoglycoside sensitivity in β-lactam-adapted populations, or the two-component regulatory system gene pmrB, which enhances penicillin sensitivity in gentamicin-resistant populations. Our findings highlight substantial variation in the evolved collateral effects among replicates, which in turn determine their potential in antibiotic therapy. © The Author 2017. Published by Oxford University Press on

Occurrence of Antibiotic resistance in some bacterial strains due to gamma radiation, heavy metals or food preservatives

International Nuclear Information System (INIS)

Mattar, Z.A.; Bashandy, A.S.

2006-01-01

The susceptibility of bacterial strains (B. cereus, Staph. aureus, Escherichia coli and Salmonella) against 10 different antibiotics that are commonly used against food borne pathogens was studied. All the tested strains were observed to tolerate up to 100 mg/l copper sulphate or lead acetate, and there was a positive correlations between the tolerance to high levels of Cu or Pb and multiple antibiotic resistance was investigated. When the food preservatives (potassium sorbate or sodium benzoate) were added to the growth medium at different concentrations, the bacterial strains were able to tolerate up to 1000 ppm potassium sorbate or sodium benzoate (MIC). The antibiotic resistance of these strains was increased when grown on media supplemented with the MIC of sodium sorbate or potassium benzoate. When these bacterial strains were irradiated at dose levels of 1 or 3 or 5 KGy and examined for antibiotic sensitivity, a correlation was observed between the increases of radiation dose up to 5 KGy and the antibiotic resistance in all the studied strains

Pharmacodynamic evaluation of commonly prescribed oral antibiotics against respiratory bacterial pathogens

Directory of Open Access Journals (Sweden)

Pignatari Antonio CC

2011-10-01

Full Text Available Abstract Background Upper and lower respiratory tract infections (RTIs account for a substantial portion of outpatient antibiotic utilization. However, the pharmacodynamic activity of commonly used oral antibiotic regimens has not been studied against clinically relevant pathogens. The objective of this study was to assess the probability of achieving the requisite pharmacodynamic exposure for oral antibacterial regimens commonly prescribed for RTIs in adults against bacterial isolates frequently involved in these processes (S. pneumoniae, H. influenzae, and M. catharralis. Methods Using a 5000-subject Monte Carlo simulation, the cumulative fractions of response (CFR, (i.e., probabilities of achieving requisite pharmacodynamic targets for the most commonly prescribed oral antibiotic regimens, as determined by a structured survey of medical prescription patterns, were assessed against local respiratory bacterial isolates from adults in São Paulo collected during the same time period. Minimal inhibitory concentration (MIC of 230 isolates of Streptococcus pneumoniae (103, Haemophilus influenzae (98, and Moraxella catharralis (29 from a previous local surveillance were used. Results The most commonly prescribed antibiotic regimens were azithromycin 500 mg QD, amoxicillin 500 mg TID, and levofloxacin 500 mg QD, accounting for 58% of the prescriptions. Varied doses of these agents, plus gatifloxacin, amoxicillin-clavulanate, moxifloxacin, and cefaclor made up the remaining regimens. Utilizing aggressive pharmacodynamic exposure targets, the only regimens to achieve greater than 90% CFR against all three pathogens were amoxicillin/amoxicillin-clavulanate 500 mg TID (> 91%, gatifloxacin 400 mg QD (100%, and moxifloxacin 400 mg QD (100%. Considering S. pneumoniae isolates alone, azithromycin 1000 mg QD also achieved greater than 90% CFR (91.3%. Conclusions The only regimens to achieve high CFR against all three pathogen populations in both scenarios

Renew or die: The molecular mechanisms of peptidoglycan recycling and antibiotic resistance in Gram-negative pathogens.

Science.gov (United States)

Domínguez-Gil, Teresa; Molina, Rafael; Alcorlo, Martín; Hermoso, Juan A

2016-09-01

Antimicrobial resistance is one of the most serious health threats. Cell-wall remodeling processes are tightly regulated to warrant bacterial survival and in some cases are directly linked to antibiotic resistance. Remodeling produces cell-wall fragments that are recycled but can also act as messengers for bacterial communication, as effector molecules in immune response and as signaling molecules triggering antibiotic resistance. This review is intended to provide state-of-the-art information about the molecular mechanisms governing this process and gather structural information of the different macromolecular machineries involved in peptidoglycan recycling in Gram-negative bacteria. The growing body of literature on the 3D structures of the corresponding macromolecules reveals an extraordinary complexity. Considering the increasing incidence and widespread emergence of Gram-negative multidrug-resistant pathogens in clinics, structural information on the main actors of the recycling process paves the way for designing novel antibiotics disrupting cellular communication in the recycling-resistance pathway. Copyright © 2016. Published by Elsevier Ltd.

Dissemination of antibiotic resistance genes from antibiotic producers to pathogens

DEFF Research Database (Denmark)

Jiang, Xinglin; Ellabaan, Mostafa M Hashim; Charusanti, Pep

2017-01-01

It has been hypothesized that some antibiotic resistance genes (ARGs) found in pathogenic bacteria derive from antibiotic-producing actinobacteria. Here we provide bioinformatic and experimental evidence supporting this hypothesis. We identify genes in proteobacteria, including some pathogens...... and experimentally test a 'carry-back' mechanism for the transfer, involving conjugative transfer of a carrier sequence from proteobacteria to actinobacteria, recombination of the carrier sequence with the actinobacterial ARG, followed by natural transformation of proteobacteria with the carrier-sandwiched ARG. Our...... results support the existence of ancient and, possibly, recent transfers of ARGs from antibiotic-producing actinobacteria to proteobacteria, and provide evidence for a defined mechanism....

Overcoming antibiotic resistance: Is siderophore Trojan horse conjugation an answer to evolving resistance in microbial pathogens?

Science.gov (United States)

Dhusia, Kalyani; Bajpai, Archana; Ramteke, P W

2018-01-10

Comparative study of siderophore biosynthesis pathway in pathogens provides potential targets for antibiotics and host drug delivery as a part of computationally feasible microbial therapy. Iron acquisition using siderophore models is an essential and well established model in all microorganisms and microbial infections a known to cause great havoc to both plant and animal. Rapid development of antibiotic resistance in bacterial as well as fungal pathogens has drawn us at a verge where one has to get rid of the traditional way of obstructing pathogen using single or multiple antibiotic/chemical inhibitors or drugs. 'Trojan horse' strategy is an answer to this imperative call where antibiotic are by far sneaked into the pathogenic cell via the siderophore receptors at cell and outer membrane. This antibiotic once gets inside, generates a 'black hole' scenario within the opportunistic pathogens via iron scarcity. For pathogens whose siderophore are not compatible to smuggle drug due to their complex conformation and stiff valence bonds, there is another approach. By means of the siderophore biosynthesis pathways, potential targets for inhibition of these siderophores in pathogenic bacteria could be achieved and thus control pathogenic virulence. Method to design artificial exogenous siderophores for pathogens that would compete and succeed the battle of intake is also covered with this review. These manipulated siderophore would enter pathogenic cell like any other siderophore but will not disperse iron due to which iron inadequacy and hence pathogens control be accomplished. The aim of this review is to offer strategies to overcome the microbial infections/pathogens using siderophore. Copyright © 2017 Elsevier B.V. All rights reserved.

How to Fight Back Against Antibiotic Resistance

DEFF Research Database (Denmark)

Dantas, Gautam; Sommer, Morten

2014-01-01

compounds. To save the era of antibiotics, scientists must figure out what it is about bacterial pathogens that makes resistance inevitable. Although most studies on drug resistance have focused on disease causing pathogens, recent efforts have shifted attention to the resistomes of nonpathogenic bacteria...

Bacterial biofilms and antibiotic resistance

Directory of Open Access Journals (Sweden)

Liliana Caldas-Arias

2015-04-01

Full Text Available Biofilms give to bacteria micro-environmental benefits; confers protection against antimicrobials. Bacteria have antibiotic resistance by conventional and unusual mechanisms leading to delayed wound healing, to increase recurrent chronic infections and nosocomial contamination of medical devices. Objective: This narrative review aims to introduce the characteristics of Bacteria-biofilms, antimicrobial resistance mechanisms and potential alternatives for prevention and control of its formation. Methods: Search strategy was performed on records: PubMed / Medline, Lilacs, Redalyc; with suppliers such as EBSCO and thesaurus MeSH and DeCS. Conclusions: Knowledge and research performance of biofilm bacteria are relevant in the search of technology for detection and measuring sensitivity to antibiotics. The identification of Bacterial-biofilms needs no-traditional microbiological diagnosis.

Host-dependent Induction of Transient Antibiotic Resistance: A Prelude to Treatment Failure

Directory of Open Access Journals (Sweden)

Jessica Z. Kubicek-Sutherland

2015-09-01

Full Text Available Current antibiotic testing does not include the potential influence of host cell environment on microbial susceptibility and antibiotic resistance, hindering appropriate therapeutic intervention. We devised a strategy to identify the presence of host–pathogen interactions that alter antibiotic efficacy in vivo. Our findings revealed a bacterial mechanism that promotes antibiotic resistance in vivo at concentrations of drug that far exceed dosages determined by standardized antimicrobial testing. This mechanism has escaped prior detection because it is reversible and operates within a subset of host tissues and cells. Bacterial pathogens are thereby protected while their survival promotes the emergence of permanent drug resistance. This host-dependent mechanism of transient antibiotic resistance is applicable to multiple pathogens and has implications for the development of more effective antimicrobial therapies.

Multicentre investigation of pathogenic bacteria and antibiotic resistance genes in Chinese patients with acute exacerbation of chronic obstructive pulmonary disease.

Science.gov (United States)

Ma, Xiuqing; Cui, Junchang; Wang, Jing; Chang, Yan; Fang, Qiuhong; Bai, Changqing; Zhou, Xiumei; Zhou, Hong; Feng, Huasong; Wang, Ying; Zhao, Weiguo; Wen, Zhongguang; Wang, Ping; Liu, Yi; Yu, Ling; Li, Chunsun; Chen, Liangan

2015-10-01

A prospective observational study to investigate the distribution and antimicrobial resistance of pathogenic bacteria in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in Beijing, China. Patients with AECOPD were recruited from 11 general hospitals. Sputum specimens were cultured and bacteria identified. Antibiotic susceptibility was determined for each isolate, and presence of antibiotic resistance genes was evaluated using polymerase chain reaction. Pathogenic bacteria were isolated from 109/318 patients (34.28%); 124 isolates of 22 pathogenic bacterial species were identified, including Klebsiella pneumoniae (16.94%), Pseudomonas aeruginosa (16.94%), Acinetobacter baumannii (11.29%), Streptococcus pneumoniae (8.87%), and Staphylococcus aureus (7.26%). S. aureus was sensitive to tigecycline, teicoplanin, vancomycin and linezolid but resistant to penicillin and levofloxacin. K.pneumoniae, P. aeruginosa, A. baumannii and E. coli were susceptible to amikacin and cefoperazone. K. pneumoniae and P. aeruginosa are the most common pathogenic bacteria in AECOPD cases in Beijing, China. Our antibiotic resistance findings may be helpful in selecting antibiotic therapy. © The Author(s) 2015.

Occurrence and Distribution of Antibiotic-resistant Bacteria and Transfer of Resistance Genes in Lake Taihu

Science.gov (United States)

Yin, Qian; Yue, Dongmei; Peng, Yuke; Liu, Ying; Xiao, Lin

2013-01-01

The overuse of antibiotics has accelerated antibiotic resistance in the natural environment, especially fresh water, generating a potential risk for public health around the world. In this study, antibiotic resistance in Lake Taihu was investigated and this was the first thorough data obtained through culture-dependent methods. High percentages of resistance to streptomycin and ampicillin among bacterial isolates were detected, followed by tetracycline and chloramphenicol. Especially high levels of ampicillin resistance in the western and northern regions were illustrated. Bacterial identification of the isolates selected for further study indicated the prevalence of some opportunistic pathogens and 62.0% of the 78 isolates exhibited multiple antibiotic resistance. The presence of ESBLs genes was in the following sequence: blaTEM > blaSHV > blaCTMX and 38.5% of the isolates had a class I integrase gene. Of all tested strains, 80.8% were able to transfer antibiotic resistance through conjugation. We also concluded that some new families of human-associated ESBLs and AmpC genes can be found in natural environmental isolates. The prevalence of antibiotic resistance and the dissemination of transferable antibiotic resistance in bacterial isolates (especially in opportunistic pathogens) was alarming and clearly indicated the urgency of realizing the health risks of antibiotic resistance to human and animal populations who are dependent on Lake Taihu for water consumption. PMID:24240317

Use of Antibiotics and Antimicrobial Resistance in Veterinary Medicine as Exemplified by the Swine Pathogen Streptococcus suis.

Science.gov (United States)

Seitz, Maren; Valentin-Weigand, Peter; Willenborg, Jörg

2016-01-01

Use of antimicrobial agents in veterinary medicine is essential to control infectious diseases, thereby keeping animals healthy and animal products safe for the consumer. On the other hand, development and spread of antimicrobial resistance is of major concern for public health. Streptococcus (S.) suis reflects a typical bacterial pathogen in modern swine production due to its facultative pathogenic nature and wide spread in the pig population. Thus, in the present review we focus on certain current aspects and problems related to antimicrobial use and resistance in S. suis as a paradigm for a bacterial pathogen affecting swine husbandry worldwide. The review includes (i) general aspects of antimicrobial use and resistance in veterinary medicine with emphasis on swine, (ii) genetic resistance mechanisms of S. suis known to contribute to bacterial survival under antibiotic selection pressure, and (iii) possible other factors which may contribute to problems in antimicrobial therapy of S. suis infections, such as bacterial persister cell formation, biofilm production, and co-infections. The latter shows that we hardly understand the complexity of factors affecting the success of antimicrobial treatment of (porcine) infectious diseases and underlines the need for further research in this field.

A bacterial antibiotic-resistance gene that complements the human multidrug-resistance P-glycoprotein gene

NARCIS (Netherlands)

van Veen, HW; Callaghan, R; Soceneantu, L; Sardini, A; Konings, WN; Higgins, CF

1998-01-01

Bacteria have developed many fascinating antibiotic-resistance mechanisms(1,2). A protein in Lactococcus lactis, LmrA, mediates antibiotic resistance by extruding amphiphilic compounds from the inner leaflet of the cytoplasmic membrane(3,4). Unlike other known bacterial multidrug-resistance

A retrospective analysis of antimicrobial resistance in bacterial pathogens in an equine hospital (2012-2015).

Science.gov (United States)

van Spijk, J N; Schmitt, S; Fürst, A E; Schoster, A

2016-06-01

Antimicrobial resistance has become an important concern in veterinary medicine. The aim of this study was to describe the rate of antimicrobial resistance in common equine pathogens and to determine the occurrence of multidrug-resistant isolates. A retrospective analysis of all susceptibility testing results from bacterial pathogens cultured from horses at the University of Zurich Equine Hospital (2012-2015) was performed. Strains exhibiting resistance to 3 or more antimicrobial categories were defined as multidrug-resistant. Susceptibility results from 303 bacterial pathogens were analyzed, most commonly Escherichia coli (60/303, 20%) and Staphylococcus aureus (40/303, 13%). High rates of acquired resistance against commonly used antimicrobials were found in most of the frequently isolated equine pathogens. The highest rate of multidrug resistance was found in isolates of Acinetobacter baumannii (23/24, 96%), followed by Enterobacter cloacae complex (24/28, 86%) and Escherichia coli (48/60, 80%). Overall, 60% of Escherichia coli isolates were phenotypically ESBL-producing and 68% of Staphylococcus spp. were phenotypically methicillin-resistant. High rates of acquired antimicrobial resistance towards commonly used antibiotics are concerning and underline the importance of individual bacteriological and antimicrobial susceptibility testing to guide antimicrobial therapy. Minimizing and optimizing antimicrobial therapy in horses is needed.

Antibiotic resistance and pathogenicity factors in Staphylococcus ...

Indian Academy of Sciences (India)

know which endemic strains of S. aureus in dairy cattle ... Antibiotic resistance; cattle; mastitis; MRSA; pathogenic genes ... recommended by Clinical and Laboratory Standards Institute ...... fnbA, eno, hla and nuc, did not show any relation to.

Bacterial genome engineering and synthetic biology: combating pathogens.

Science.gov (United States)

Krishnamurthy, Malathy; Moore, Richard T; Rajamani, Sathish; Panchal, Rekha G

2016-11-04

The emergence and prevalence of multidrug resistant (MDR) pathogenic bacteria poses a serious threat to human and animal health globally. Nosocomial infections and common ailments such as pneumonia, wound, urinary tract, and bloodstream infections are becoming more challenging to treat due to the rapid spread of MDR pathogenic bacteria. According to recent reports by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC), there is an unprecedented increase in the occurrence of MDR infections worldwide. The rise in these infections has generated an economic strain worldwide, prompting the WHO to endorse a global action plan to improve awareness and understanding of antimicrobial resistance. This health crisis necessitates an immediate action to target the underlying mechanisms of drug resistance in bacteria. The advent of new bacterial genome engineering and synthetic biology (SB) tools is providing promising diagnostic and treatment plans to monitor and treat widespread recalcitrant bacterial infections. Key advances in genetic engineering approaches can successfully aid in targeting and editing pathogenic bacterial genomes for understanding and mitigating drug resistance mechanisms. In this review, we discuss the application of specific genome engineering and SB methods such as recombineering, clustered regularly interspaced short palindromic repeats (CRISPR), and bacterial cell-cell signaling mechanisms for pathogen targeting. The utility of these tools in developing antibacterial strategies such as novel antibiotic production, phage therapy, diagnostics and vaccine production to name a few, are also highlighted. The prevalent use of antibiotics and the spread of MDR bacteria raise the prospect of a post-antibiotic era, which underscores the need for developing novel therapeutics to target MDR pathogens. The development of enabling SB technologies offers promising solutions to deliver safe and effective antibacterial therapies.

Bacterial Community Shift Drives Antibiotic Resistance Promotion during Drinking Water Chlorination.

Science.gov (United States)

Jia, Shuyu; Shi, Peng; Hu, Qing; Li, Bing; Zhang, Tong; Zhang, Xu-Xiang

2015-10-20

For comprehensive insights into the effects of chlorination, a widely used disinfection technology, on bacterial community and antibiotic resistome in drinking water, this study applied high-throughput sequencing and metagenomic approaches to investigate the changing patterns of antibiotic resistance genes (ARGs) and bacterial community in a drinking water treatment and distribution system. At genus level, chlorination could effectively remove Methylophilus, Methylotenera, Limnobacter, and Polynucleobacter, while increase the relative abundance of Pseudomonas, Acidovorax, Sphingomonas, Pleomonas, and Undibacterium in the drinking water. A total of 151 ARGs within 15 types were detectable in the drinking water, and chlorination evidently increased their total relative abundance while reduced their diversity in the opportunistic bacteria (p < 0.05). Residual chlorine was identified as the key contributing factor driving the bacterial community shift and resistome alteration. As the dominant persistent ARGs in the treatment and distribution system, multidrug resistance genes (mainly encoding resistance-nodulation-cell division transportation system) and bacitracin resistance gene bacA were mainly carried by chlorine-resistant bacteria Pseudomonas and Acidovorax, which mainly contributed to the ARGs abundance increase. The strong correlation between bacterial community shift and antibiotic resistome alteration observed in this study may shed new light on the mechanism behind the chlorination effects on antibiotic resistance.

Reversing Bacterial Resistance to Antibiotics by Phage-Mediated Delivery of Dominant Sensitive Genes

OpenAIRE

Edgar, Rotem; Friedman, Nir; Molshanski-Mor, Shahar; Qimron, Udi

2012-01-01

Pathogen resistance to antibiotics is a rapidly growing problem, leading to an urgent need for novel antimicrobial agents. Unfortunately, development of new antibiotics faces numerous obstacles, and a method that resensitizes pathogens to approved antibiotics therefore holds key advantages. We present a proof of principle for a system that restores antibiotic efficiency by reversing pathogen resistance. This system uses temperate phages to introduce, by lysogenization, the genes rpsL and gyrA...

Mechanisms of action of systemic antibiotics used in periodontal treatment and mechanisms of bacterial resistance to these drugs

Directory of Open Access Journals (Sweden)

Geisla Mary Silva Soares

2012-06-01

Full Text Available Antibiotics are important adjuncts in the treatment of infectious diseases, including periodontitis. The most severe criticisms to the indiscriminate use of these drugs are their side effects and, especially, the development of bacterial resistance. The knowledge of the biological mechanisms involved with the antibiotic usage would help the medical and dental communities to overcome these two problems. Therefore, the aim of this manuscript was to review the mechanisms of action of the antibiotics most commonly used in the periodontal treatment (i.e. penicillin, tetracycline, macrolide and metronidazole and the main mechanisms of bacterial resistance to these drugs. Antimicrobial resistance can be classified into three groups: intrinsic, mutational and acquired. Penicillin, tetracycline and erythromycin are broad-spectrum drugs, effective against gram-positive and gram-negative microorganisms. Bacterial resistance to penicillin may occur due to diminished permeability of the bacterial cell to the antibiotic; alteration of the penicillin-binding proteins, or production of β-lactamases. However, a very small proportion of the subgingival microbiota is resistant to penicillins. Bacteria become resistant to tetracyclines or macrolides by limiting their access to the cell, by altering the ribosome in order to prevent effective binding of the drug, or by producing tetracycline/macrolide-inactivating enzymes. Periodontal pathogens may become resistant to these drugs. Finally, metronidazole can be considered a prodrug in the sense that it requires metabolic activation by strict anaerobe microorganisms. Acquired resistance to this drug has rarely been reported. Due to these low rates of resistance and to its high activity against the gram-negative anaerobic bacterial species, metronidazole is a promising drug for treating periodontal infections.

Investigation of environmental drivers of antimicrobial resistance in foodborne bacterial pathogens in antibiotic-free, all natural, pastured poultry flocks.

Science.gov (United States)

Question: In the absence of antibiotic use within pastured poultry production, what are potential environmental variables that drive the antimicrobial sensitivity patterns of bacterial foodborne pathogens isolated from these flocks? Purpose: The objective of this study is to examine environmental f...

Treatment of acute otitis media - challenges in the era of antibiotic resistance.

Science.gov (United States)

Dagan, R

2000-12-08

The last decade is characterized by the increase in antibiotic resistance among respiratory bacterial pathogens in the presence of only modest progress in the development of new antibacterial agents to overcome this resistance. A series of recent studies show clearly that the increased resistance among the main AOM pathogens (namely Streptococcus pneumoniae and Haemophilus influenzae) is associated with a dramatic decrease in bacteriologic response to antibiotic treatment, which in turn has an impact on clinical response. Thus, the individual patient is affected by the increasing antibiotic resistance. Moreover, the society as a whole is now also affected because the carriage and spread of antibiotic resistant AOM pathogens is remarkably impacted by antibiotic treatment. New studies show the remarkable ability of antibiotics to rapidly promote nasopharyngeal carriage and spread of antibiotic-resistant AOM pathogens. In these studies, the increase in carriage of antibiotic resistant S. pneumoniae is shown already after 3-4 days from initiation of antibiotic treatment and may last for weeks to months after treatment. Children carrying antibiotic-resistant organisms transmit those organisms to their family and to their day care centers and thus a vicious cycle is created in which increased antibiotic resistance with decreased response leads to increased antibiotic use, which in turn leads to further increase in resistance. New antibiotics are not likely to improve this situation. It is clear that the challenge in the next decade is to prevent AOM rather than to treat it. Efforts to prevent AOM include improved environmental factors, immunization with bacterial and viral vaccines and some creative measures such as prevention of colonization and attachment to epithelium of AOM pathogens. Whether these efforts will prove successful or, even if successful, will only modify the clinical and bacteriologic picture presenting new challenges, only time will tell.

Helicobacter pylori strains from a Nigerian cohort show divergent antibiotic resistance rates and a uniform pathogenicity profile.

Directory of Open Access Journals (Sweden)

Ute Harrison

Full Text Available Antibiotic resistance in Helicobacter pylori is a factor preventing its successful eradication. Particularly in developing countries, resistance against commonly used antibiotics is widespread. Here, we present an epidemiological study from Nigeria with 111 isolates. We analyzed the associated disease outcome, and performed a detailed characterization of these isolated strains with respect to their antibiotic susceptibility and their virulence characteristics. Furthermore, statistical analysis was performed on microbiological data as well as patient information and the results of the gastroenterological examination. We found that the variability concerning the production of virulence factors between strains was minimal, with 96.4% of isolates being CagA-positive and 92.8% producing detectable VacA levels. In addition, high frequency of bacterial resistance was observed for metronidazole (99.1%, followed by amoxicillin (33.3%, clarithromycin (14.4% and tetracycline (4.5%. In conclusion, this study indicated that the infection rate of H. pylori infection within the cohort in the present study was surprisingly low (36.6%. Furthermore, an average gastric pathology was observed by histological grading and bacterial isolates showed a uniform pathogenicity profile while indicating divergent antibiotic resistance rates.

Antibiotic Discovery: Combatting Bacterial Resistance in Cells and in Biofilm Communities

Directory of Open Access Journals (Sweden)

Anahit Penesyan

2015-03-01

Full Text Available Bacterial resistance is a rapidly escalating threat to public health as our arsenal of effective antibiotics dwindles. Therefore, there is an urgent need for new antibiotics. Drug discovery has historically focused on bacteria growing in planktonic cultures. Many antibiotics were originally developed to target individual bacterial cells, being assessed in vitro against microorganisms in a planktonic mode of life. However, towards the end of the 20th century it became clear that many bacteria live as complex communities called biofilms in their natural habitat, and this includes habitats within a human host. The biofilm mode of life provides advantages to microorganisms, such as enhanced resistance towards environmental stresses, including antibiotic challenge. The community level resistance provided by biofilms is distinct from resistance mechanisms that operate at a cellular level, and cannot be overlooked in the development of novel strategies to combat infectious diseases. The review compares mechanisms of antibiotic resistance at cellular and community levels in the light of past and present antibiotic discovery efforts. Future perspectives on novel strategies for treatment of biofilm-related infectious diseases are explored.

Occurrence of antibiotic resistant bacteria in dogs presented with ...

African Journals Online (AJOL)

Otitis is one of the most common infections in dogs. This has been associated with misuse of antibiotics thereby promoting the emergence of multi-resistant micro-organisms. This study was conducted to determine the occurrence and the antibiotic resistance pattern of bacterial pathogens associated with otitis in dogs ...

Antibiotic resistance of bacterial biofilms

DEFF Research Database (Denmark)

Hoiby, N.; Bjarnsholt, T.; Givskov, M.

2010-01-01

A biofilm is a structured consortium of bacteria embedded in a self-produced polymer matrix consisting of polysaccharide, protein and DNA. Bacterial biofilms cause chronic infections because they show increased tolerance to antibiotics and disinfectant chemicals as well as resisting phagocytosis...... and other components of the body's defence system. The persistence of, for example, staphylococcal infections related to foreign bodies is due to biofilm formation. Likewise, chronic Pseudomonas aeruginosa lung infection in cystic fibrosis patients is caused by biofilm-growing mucoid strains....... Characteristically, gradients of nutrients and oxygen exist from the top to the bottom of biofilms and these gradients are associated with decreased bacterial metabolic activity and increased doubling times of the bacterial cells; it is these more or less dormant cells that are responsible for some of the tolerance...

Genetic Mechanisms of Antibiotic Resistance and the Role of Antibiotic Adjuvants.

Science.gov (United States)

Pontes, Daniela Santos; de Araujo, Rodrigo Santos Aquino; Dantas, Natalina; Scotti, Luciana; Scotti, Marcus Tullius; de Moura, Ricardo Olimpio; Mendonca-Junior, Francisco Jaime Bezerra

2018-01-01

The ever increasing number of multidrug-resistant microorganism pathogens has become a great and global public health threat. Antibiotic mechanisms of action and the opposing mechanisms of resistance are intimately associated, but comprehension of the biochemical and molecular functions of such drugs is not a simple exercise. Both the environment, and genetic settings contribute to alterations in phenotypic resistance (natural bacterial evolution), and make it difficult to control the emergence and impacts of antibiotic resistance. Under such circumstances, comprehension of how bacteria develop and/or acquire antibiotic resistance genes (ARG) has a critical role in developing propositions to fight against these superbugs, and to search for new drugs. In this review, we present and discuss both general information and examples of common genetic and molecular mechanisms related to antibiotic resistance, as well as how the expression and interactions of ARGs are important to drug resistance. At the same time, we focus on the recent achievements in the search for antibiotic adjuvants, which help combat antibiotic resistance through deactivation of bacterial mechanisms of action such as β-lactamases. Recent advances involving the use of anti-resistance drugs such as: efflux pump inhibitors; anti-virulence drugs; drugs against quorum sensing; and against type II/III secretion systems are revealed. Such antibiotic adjuvants (as explored herein) collaborate against the problems of antibiotic resistance, and may restore or prolong the therapeutic activity of known antibiotics. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Selective labelling and eradication of antibiotic-tolerant bacterial populations in Pseudomonas aeruginosa biofilms

DEFF Research Database (Denmark)

Chua, Song Lin; Yam, Joey Kuok Hoong; Hao, Piliang

2016-01-01

Drug resistance and tolerance greatly diminish the therapeutic potential of antibiotics against pathogens. Antibiotic tolerance by bacterial biofilms often leads to persistent infections, but its mechanisms are unclear. Here we use a proteomics approach, pulsed stable isotope labelling with amino...... acids (pulsed-SILAC), to quantify newly expressed proteins in colistin-tolerant subpopulations of Pseudomonas aeruginosa biofilms (colistin is a 'last-resort' antibiotic against multidrug-resistant Gram-negative pathogens). Migration is essential for the formation of colistin-tolerant biofilm...

Effects of Metals on Antibiotic Resistance and Conjugal Plasmid Transfer in Soil Bacterial Communities

DEFF Research Database (Denmark)

Song, Jianxiao

Antibiotic resistance currently represents one of the biggest challenges for human health and in recent years the environmental dimension of antibiotic resistance has been increasingly recognized. The soil environment serves as an important reservoir of antibiotic resistance determinants. In addi...... adaptation to metal stress did not significantly increase the permissiveness of the soil bacterial community towards conjugal plasmid transfer........ In addition to direct selection of antibiotic resistance by antibiotics, metals may co-select for antibiotic resistance via different mechanisms causing environmental selection of antibiotic resistance in metal contaminated soils. Horizontal gene transfer of mobile genetic elements (MGEs) like plasmids...... is generally considered one of the most important co-selection mechanisms as multiple resistance genes can be located on the same MGE. This PhD thesis focused on the impact of metals (Cu and Zn) on the development of antibiotic resistance in bacterial communities in soils exposed to different degrees...

Macrolide antibiotic interaction and resistance on the bacterial ribosome.

Science.gov (United States)

Poehlsgaard, Jacob; Douthwaite, Stephen

2003-02-01

Our understanding of the fine structure of many antibiotic target sites has reached a new level of enlightenment in the last couple of years due to the advent, by X-ray crystallography, of high-resolution structures of the bacterial ribosome. Many classes of clinically useful antibiotics bind to the ribosome to inhibit bacterial protein synthesis. Macrolide, lincosamide and streptogramin B (MLSB) antibiotics form one of the largest groups, and bind to the same site on the 50S ribosomal subunit. Here, we review the molecular details of the ribosomal MLSB site to put into perspective the main points from a wealth of biochemical and genetic data that have been collected over several decades. The information is now available to understand, at atomic resolution, how macrolide antibiotics interact with their ribosomal target, how the target is altered to confer resistance, and in which directions we need to look if we are to rationally design better drugs to overcome the extant resistance mechanisms.

The intrinsic resistome of bacterial pathogens.

Science.gov (United States)

Olivares, Jorge; Bernardini, Alejandra; Garcia-Leon, Guillermo; Corona, Fernando; B Sanchez, Maria; Martinez, Jose L

2013-01-01

Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyze recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice.

The intrinsic resistome of bacterial pathogens

Directory of Open Access Journals (Sweden)

Jorge Andrés Olivares Pacheco

2013-04-01

Full Text Available Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally a low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyse recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice.

VRprofile: gene-cluster-detection-based profiling of virulence and antibiotic resistance traits encoded within genome sequences of pathogenic bacteria.

Science.gov (United States)

Li, Jun; Tai, Cui; Deng, Zixin; Zhong, Weihong; He, Yongqun; Ou, Hong-Yu

2017-01-10

VRprofile is a Web server that facilitates rapid investigation of virulence and antibiotic resistance genes, as well as extends these trait transfer-related genetic contexts, in newly sequenced pathogenic bacterial genomes. The used backend database MobilomeDB was firstly built on sets of known gene cluster loci of bacterial type III/IV/VI/VII secretion systems and mobile genetic elements, including integrative and conjugative elements, prophages, class I integrons, IS elements and pathogenicity/antibiotic resistance islands. VRprofile is thus able to co-localize the homologs of these conserved gene clusters using HMMer or BLASTp searches. With the integration of the homologous gene cluster search module with a sequence composition module, VRprofile has exhibited better performance for island-like region predictions than the other widely used methods. In addition, VRprofile also provides an integrated Web interface for aligning and visualizing identified gene clusters with MobilomeDB-archived gene clusters, or a variety set of bacterial genomes. VRprofile might contribute to meet the increasing demands of re-annotations of bacterial variable regions, and aid in the real-time definitions of disease-relevant gene clusters in pathogenic bacteria of interest. VRprofile is freely available at http://bioinfo-mml.sjtu.edu.cn/VRprofile. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Antibiotic susceptibility profiles of oral pathogens

NARCIS (Netherlands)

Veloo, A. C. M.; Seme, K.; Raangs, Gerwin; Rurenga, P.; Singadji, Z.; Wekema - Mulder, G.; van Winkelhoff, A. J.

2012-01-01

Periodontitis is a bacterial disease that can be treated with systemic antibiotics. The aim of this study was to establish the antibiotic susceptibility profiles of five periodontal pathogens to six commonly used antibiotics in periodontics. A total of 247 periodontal bacterial isolates were tested

Microbial profile, antibiotic sensitivity and heat resistance of bacterial ...

African Journals Online (AJOL)

Aim: This study was aimed at determining the prevalence, antibiotic resistance and heat resistance profile of bacterial isolates obtained from ready to eat roasted beef (suya) sold in Abuja, Nigeria. Methods and Results: Fifty samples of suya were purchased from different vendors within the Federal Capital Territory and ...

Reversing bacterial resistance to antibiotics by phage-mediated delivery of dominant sensitive genes.

Science.gov (United States)

Edgar, Rotem; Friedman, Nir; Molshanski-Mor, Shahar; Qimron, Udi

2012-02-01

Pathogen resistance to antibiotics is a rapidly growing problem, leading to an urgent need for novel antimicrobial agents. Unfortunately, development of new antibiotics faces numerous obstacles, and a method that resensitizes pathogens to approved antibiotics therefore holds key advantages. We present a proof of principle for a system that restores antibiotic efficiency by reversing pathogen resistance. This system uses temperate phages to introduce, by lysogenization, the genes rpsL and gyrA conferring sensitivity in a dominant fashion to two antibiotics, streptomycin and nalidixic acid, respectively. Unique selective pressure is generated to enrich for bacteria that harbor the phages carrying the sensitizing constructs. This selection pressure is based on a toxic compound, tellurite, and therefore does not forfeit any antibiotic for the sensitization procedure. We further demonstrate a possible way of reducing undesirable recombination events by synthesizing dominant sensitive genes with major barriers to homologous recombination. Such synthesis does not significantly reduce the gene's sensitization ability. Unlike conventional bacteriophage therapy, the system does not rely on the phage's ability to kill pathogens in the infected host, but instead, on its ability to deliver genetic constructs into the bacteria and thus render them sensitive to antibiotics prior to host infection. We believe that transfer of the sensitizing cassette by the constructed phage will significantly enrich for antibiotic-treatable pathogens on hospital surfaces. Broad usage of the proposed system, in contrast to antibiotics and phage therapy, will potentially change the nature of nosocomial infections toward being more susceptible to antibiotics rather than more resistant.

Antibiotic resistance in human peri-implantitis microbiota

NARCIS (Netherlands)

Rams, Thomas E.; Degener, John E.; van Winkelhoff, Arie J.

ObjectivesBecause antimicrobial therapy is often employed in the treatment of infectious dental implant complications, this study determined the occurrence of in vitro antibiotic resistance among putative peri-implantitis bacterial pathogens. MethodsSubmucosal biofilm specimens were cultured from

Metagenomic analysis of bacterial community composition and antibiotic resistance genes in a wastewater treatment plant and its receiving surface water.

Science.gov (United States)

Tang, Junying; Bu, Yuanqing; Zhang, Xu-Xiang; Huang, Kailong; He, Xiwei; Ye, Lin; Shan, Zhengjun; Ren, Hongqiang

2016-10-01

The presence of pathogenic bacteria and the dissemination of antibiotic resistance genes (ARGs) may pose big risks to the rivers that receive the effluent from municipal wastewater treatment plants (WWTPs). In this study, we investigated the changes of bacterial community and ARGs along treatment processes of one WWTP, and examined the effects of the effluent discharge on the bacterial community and ARGs in the receiving river. Pyrosequencing was applied to reveal bacterial community composition including potential bacterial pathogen, and Illumina high-throughput sequencing was used for profiling ARGs. The results showed that the WWTP had good removal efficiency on potential pathogenic bacteria (especially Arcobacter butzleri) and ARGs. Moreover, the bacterial communities of downstream and upstream of the river showed no significant difference. However, the increase in the abundance of potential pathogens and ARGs at effluent outfall was observed, indicating that WWTP effluent might contribute to the dissemination of potential pathogenic bacteria and ARGs in the receiving river. Copyright © 2016 Elsevier Inc. All rights reserved.

Antimicrobial resistance of mastitis pathogens.

Science.gov (United States)

Oliver, Stephen P; Murinda, Shelton E

2012-07-01

Antibiotics are used extensively in the dairy industry to combat disease and to improve animal performance. Antibiotics such as penicillin, cephalosporin, streptomycin, and tetracycline are used for the treatment and prevention of diseases affecting dairy cows caused by a variety of gram-positive and gram-negative bacteria. Antibiotics are often administrated routinely to entire herds to prevent mastitis during the dry period. An increase in the incidence of disease in a herd generally results in increased use of antimicrobials, which in turn increases the potential for antibiotic residues in milk and the potential for increased bacterial resistance to antimicrobials. Continued use of antibiotics in the treatment and prevention of diseases of dairy cows will continue to be scrutinized. It is clear that strategies employing the prudent use of antimicrobials are needed. This clearly illustrates the importance of effective herd disease prevention and control programs. Based on studies published to date, scientific evidence does not support widespread, emerging resistance among mastitis pathogens to antibacterial drugs even though many of these antibiotics have been used in the dairy industry for treatment and prevention of disease for several decades. However, it is clear that use of antibiotics in dairy cows can contribute to increased antimicrobial resistance. While antimicrobial resistance does occur, we are of the opinion that the advantages of using antibiotics for the treatment of mastitis far outweigh the disadvantages. The clinical consequences of antimicrobial resistance of dairy pathogens affecting humans appear small. Antimicrobial resistance among dairy pathogens, particularly those found in milk, is likely not a human health concern as long as the milk is pasteurized. However, there are an increasing number of people who choose to consume raw milk. Transmission of an antimicrobial-resistant mastitis pathogen and/or foodborne pathogen to humans could occur

Antibiotic Resistance and the Biology of History.

Science.gov (United States)

Landecker, Hannah

2016-12-01

Beginning in the 1940s, mass production of antibiotics involved the industrial-scale growth of microorganisms to harvest their metabolic products. Unfortunately, the use of antibiotics selects for resistance at answering scale. The turn to the study of antibiotic resistance in microbiology and medicine is examined, focusing on the realization that individual therapies targeted at single pathogens in individual bodies are environmental events affecting bacterial evolution far beyond bodies. In turning to biological manifestations of antibiotic use, sciences fathom material outcomes of their own previous concepts. Archival work with stored soil and clinical samples produces a record described here as 'the biology of history': the physical registration of human history in bacterial life. This account thus foregrounds the importance of understanding both the materiality of history and the historicity of matter in theories and concepts of life today.

Trojan Horse Antibiotics-A Novel Way to Circumvent Gram-Negative Bacterial Resistance?

Science.gov (United States)

Tillotson, Glenn S

2016-01-01

Antibiotic resistance has been emerged as a major global health problem. In particular, gram-negative species pose a significant clinical challenge as bacteria develop or acquire more resistance mechanisms. Often, these bacteria possess multiple resistance mechanisms, thus nullifying most of the major classes of drugs. Novel approaches to this issue are urgently required. However, the challenges of developing new agents are immense. Introducing novel agents is fraught with hurdles, thus adapting known antibiotic classes by altering their chemical structure could be a way forward. A chemical addition to existing antibiotics known as a siderophore could be a solution to the gram-negative resistance issue. Siderophore molecules rely on the bacterial innate need for iron ions and thus can utilize a Trojan Horse approach to gain access to the bacterial cell. The current approaches to using this potential method are reviewed.

The analysis of antibiotic consumption and bacterial resistance in tertiary Healthcare Centre Niš

Directory of Open Access Journals (Sweden)

Veličković-Radovanović Radmila M.

2016-01-01

Full Text Available Introduction: Antibiotics are the most frequently used drugs in hospitalized patients, but studies have shown that the prescribed antibiotics may be inappropriate and may contribute to bacterial resistance. The aim of this work is the evaluation of antibiotic consumption in Clinical Centre Nis, Serbia from 2011 to 2014, with the focus on the monitoring of the ceftriaxone (CTX and ciprofloxacin (CIP utilization. Secondly, we screened bacterial resistance towards monitored antibiotics used for intra-abdominal infection (IAI and urinary tract infection (UTI in tertiary healthcare institution. Methods: Antibiotics consumption and antimicrobial resistance were monitored in the tertiary care university hospital-Clinical Centre Nis from 2011 to 2014. Data on the use of antibiotics in inpatients were obtained and expressed as defined daily doses per 100 bed days (DBD. Bacterial resistances were given as percentages of resistant isolates. Results: During the investigation period the use of cephalosporins increased by 6.39 %, from 2011 to 2013, but in 2014 there was a reduction in its consumption by 16.46 %. Penicillins consumption had a decreasing trend, whereas quinolones consumption was variable during observation period. The resistance of K. pneumoniae to CTX and CIP for the isolates from IAI, and resistance of E. coli to analyze antibiotics for isolates from UTI showed increasing trend within observed period of time. Conclusions: Our findings shows that cephalosporins were the most frequently used antibiotics in Clinical Centre Nis, and they were followed by penicillins and quinolones. Additionally, K. pneumoniae resistance to CTX and CIP increased markedly in IAI, while E. coli resistance showed an increasing trend to CTX and CIP in UTI over the study period.

On the contribution of reclaimed wastewater irrigation to the potential exposure of humans to antibiotics, antibiotic resistant bacteria and antibiotic resistance genes - NEREUS COST Action ES1403 position paper

DEFF Research Database (Denmark)

Piña, Benjamin; Bayona, Josep M.; Christou, Anastasis

2018-01-01

Antibiotic resistance (AR) is becoming a worldwide threat due to the increasing occurrence of antibiotic-resistant pathogenic bacterial strains. There is a general consensus about the potential implications of the use of antibiotics in livestock on the onset of antibiotic resistant bacteria (ARB......), mainly through meat consumption. However, the ever-increasing use of reclaimed wastewater (RWW) in agriculture may also contribute significantly to the non-accounted exposure to antibiotics, ARB, and antibiotic resistance genes (ARGs). This position paper aims at evaluating the current knowledge...... concerning the occurrence of antibiotics, ARBs, and ARGs in edible parts of different common crops irrigated with RWW. We will discuss which regulations on the use of RWW may contribute to the minimization of the prevalence of these contaminants in crops, and provide recommendations on how to minimize...

Occurrence of antimicrobial resistance among bacterial pathogens

OpenAIRE

Hendriksen, Rene S.; Mevius, Dik J.; Schroeter, Andreas; Teale, Christopher; Jouy, Eric; Butaye, Patrick; Franco, Alessia; Utinane, Andra; Amado, Alice; Moreno, Miguel; Greko, Christina; Stärk, Katharina D.C.; Berghold, Christian; Myllyniemi, Anna-Liisa; Hoszowski, Andrzej

2008-01-01

Background: The project "Antibiotic resistance in bacteria of animal origin – II" (ARBAO-II) was funded by the European Union (FAIR5-QLK2-2002-01146) for the period 2003–05. The aim of this project was to establish a program for the continuous monitoring of antimicrobial susceptibility of pathogenic and indicator bacteria from food animals using validated and harmonised methodologies. In this report the first data on the occurrence of antimicrobial resistance among bacteria cau...

Photoinactivation of major bacterial pathogens in aquaculture

Directory of Open Access Journals (Sweden)

Heyong Jin Roh

2016-08-01

Full Text Available Abstract Background Significant increases in the bacterial resistance to various antibiotics have been found in fish farms. Non-antibiotic therapies for infectious diseases in aquaculture are needed. In recent years, light-emitting diode technology has been applied to the inactivation of pathogens, especially those affecting humans. The purpose of this study was to assess the effect of blue light (wavelengths 405 and 465 nm on seven major bacterial pathogens that affect fish and shellfish important in aquaculture. Results We successfully demonstrate inactivation activity of a 405/465-nm LED on selected bacterial pathogens. Although some bacteria were not fully inactivated by the 465-nm light, the 405-nm light had a bactericidal effect against all seven pathogens, indicating that blue light can be effective without the addition of a photosensitizer. Photobacterium damselae, Vibrio anguillarum, and Edwardsiella tarda were the most susceptible to the 405-nm light (36.1, 41.2, and 68.4 J cm−2, respectively, produced one log reduction in the bacterial populations, whereas Streptococcus parauberis was the least susceptible (153.8 J cm−2 per one log reduction. In general, optical density (OD values indicated that higher bacterial densities were associated with lower inactivating efficacy, with the exception of P. damselae and Vibrio harveyi. In conclusion, growth of the bacterial fish and shellfish pathogens evaluated in this study was inactivated by exposure to either the 405- or 465-nm light. In addition, inactivation was dependent on exposure time. Conclusions This study presents that blue LED has potentially alternative therapy for treating fish and shellfish bacterial pathogens. It has great advantages in aspect of eco-friendly treating methods differed from antimicrobial methods.

Genomics of antibiotic-resistance prediction in Pseudomonas aeruginosa.

Science.gov (United States)

Jeukens, Julie; Freschi, Luca; Kukavica-Ibrulj, Irena; Emond-Rheault, Jean-Guillaume; Tucker, Nicholas P; Levesque, Roger C

2017-06-02

Antibiotic resistance is a worldwide health issue spreading quickly among human and animal pathogens, as well as environmental bacteria. Misuse of antibiotics has an impact on the selection of resistant bacteria, thus contributing to an increase in the occurrence of resistant genotypes that emerge via spontaneous mutation or are acquired by horizontal gene transfer. There is a specific and urgent need not only to detect antimicrobial resistance but also to predict antibiotic resistance in silico. We now have the capability to sequence hundreds of bacterial genomes per week, including assembly and annotation. Novel and forthcoming bioinformatics tools can predict the resistome and the mobilome with a level of sophistication not previously possible. Coupled with bacterial strain collections and databases containing strain metadata, prediction of antibiotic resistance and the potential for virulence are moving rapidly toward a novel approach in molecular epidemiology. Here, we present a model system in antibiotic-resistance prediction, along with its promises and limitations. As it is commonly multidrug resistant, Pseudomonas aeruginosa causes infections that are often difficult to eradicate. We review novel approaches for genotype prediction of antibiotic resistance. We discuss the generation of microbial sequence data for real-time patient management and the prediction of antimicrobial resistance. © 2017 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals Inc. on behalf of The New York Academy of Sciences.

[State-of-the-art status on airborne antibiotic resistant bacteria and antibiotic resistance genes].

Science.gov (United States)

Li, J; Yao, M S

2018-04-06

The world is facing more deaths due to increasing antibiotic-resistant bacterial infections and the shortage of new highly effective antibiotics, however the air media as its important transmission route has not been adequately studied. Based on the latest literature acquired in this work, we have discussed the state-of-the-art research progress of the concentration, distribution and spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in different environmental air media, and also analyzed some future prevention and control measures. The large use of antibiotics in the medical settings and animal husbandry places has resulted in higher abundances of ARB and ARGs in the relevant and surrounding atmosphere than in urban and general indoor air environments. ARGs can be spread by adhering to airborne particles, and researchers have also found that air media contain more abundant ARGs than other environmental media such as soil, water and sediment. It was suggested in this review that strengthening the monitoring, study on spreading factors and biological toxicity, and also research and development on pathogen accurate diagnosis and new green antibiotic are expected to help effectively monitor, prevent and control of the impacts of airborne resistant bacteria and resistance genes on both human and ecologies.

Targeted Treatment for Bacterial Infections: Prospects for Pathogen-Specific Antibiotics Coupled with Rapid Diagnostics

OpenAIRE

Maxson, Tucker; Mitchell, Douglas A.

2015-01-01

Antibiotics are a cornerstone of modern medicine and have significantly reduced the burden of infectious diseases. However, commonly used broad-spectrum antibiotics can cause major collateral damage to the human microbiome, causing complications ranging from antibiotic-associated colitis to the rapid spread of resistance. Employing narrower spectrum antibiotics targeting specific pathogens may alleviate this predicament as well as provide additional tools to expand an antibiotic repertoire th...

Selective labelling and eradication of antibiotic-tolerant bacterial populations in Pseudomonas aeruginosa biofilms

Science.gov (United States)

Chua, Song Lin; Yam, Joey Kuok Hoong; Hao, Piliang; Adav, Sunil S.; Salido, May Margarette; Liu, Yang; Givskov, Michael; Sze, Siu Kwan; Tolker-Nielsen, Tim; Yang, Liang

2016-01-01

Drug resistance and tolerance greatly diminish the therapeutic potential of antibiotics against pathogens. Antibiotic tolerance by bacterial biofilms often leads to persistent infections, but its mechanisms are unclear. Here we use a proteomics approach, pulsed stable isotope labelling with amino acids (pulsed-SILAC), to quantify newly expressed proteins in colistin-tolerant subpopulations of Pseudomonas aeruginosa biofilms (colistin is a ‘last-resort' antibiotic against multidrug-resistant Gram-negative pathogens). Migration is essential for the formation of colistin-tolerant biofilm subpopulations, with colistin-tolerant cells using type IV pili to migrate onto the top of the colistin-killed biofilm. The colistin-tolerant cells employ quorum sensing (QS) to initiate the formation of new colistin-tolerant subpopulations, highlighting multicellular behaviour in antibiotic tolerance development. The macrolide erythromycin, which has been previously shown to inhibit the motility and QS of P. aeruginosa, boosts biofilm eradication by colistin. Our work provides insights on the mechanisms underlying the formation of antibiotic-tolerant populations in bacterial biofilms and indicates research avenues for designing more efficient treatments against biofilm-associated infections. PMID:26892159

Selective labelling and eradication of antibiotic-tolerant bacterial populations in Pseudomonas aeruginosa biofilms.

Science.gov (United States)

Chua, Song Lin; Yam, Joey Kuok Hoong; Hao, Piliang; Adav, Sunil S; Salido, May Margarette; Liu, Yang; Givskov, Michael; Sze, Siu Kwan; Tolker-Nielsen, Tim; Yang, Liang

2016-02-19

Drug resistance and tolerance greatly diminish the therapeutic potential of antibiotics against pathogens. Antibiotic tolerance by bacterial biofilms often leads to persistent infections, but its mechanisms are unclear. Here we use a proteomics approach, pulsed stable isotope labelling with amino acids (pulsed-SILAC), to quantify newly expressed proteins in colistin-tolerant subpopulations of Pseudomonas aeruginosa biofilms (colistin is a 'last-resort' antibiotic against multidrug-resistant Gram-negative pathogens). Migration is essential for the formation of colistin-tolerant biofilm subpopulations, with colistin-tolerant cells using type IV pili to migrate onto the top of the colistin-killed biofilm. The colistin-tolerant cells employ quorum sensing (QS) to initiate the formation of new colistin-tolerant subpopulations, highlighting multicellular behaviour in antibiotic tolerance development. The macrolide erythromycin, which has been previously shown to inhibit the motility and QS of P. aeruginosa, boosts biofilm eradication by colistin. Our work provides insights on the mechanisms underlying the formation of antibiotic-tolerant populations in bacterial biofilms and indicates research avenues for designing more efficient treatments against biofilm-associated infections.

Molecular Level Investigation of Staphylococci’s Resistance Mechanisms to Antibiotics

Directory of Open Access Journals (Sweden)

Lavinia Lorena PRUTEANU

2017-09-01

Full Text Available Polymerase chain reaction (PCR techniques development allows elaboration of many assays for identification of bacteria’s resistance mechanisms to antibiotics. Following this idea, the results of molecular level investigation of bacteria’s resistance mechanisms to antibiotics may give many opportunities to find more rapid methods for identifying the genes which are responsible for antibiotic resistance induction. The aim of this study was to investigate antibiotic resistance genes in Staphylococcus bacteria on molecular level. As classes of antibiotics it was used macrolides-lincosamides-streptogramin B (MLSB and beta-lactams. In the proposed study the bacterial strains are represented by 50 isolates of Staphylococcus. The bacterial strains were analyzed using polymerase chain reaction to identify the nuc, tuf, tst, sea, pathogenic activity genes. After this, the bacteria were tested for ermA, ermB, ermC genes and for mecA, femA which are involved in resistance to macrolides, lincosamides, streptogramin B and to beta-lactams, respectively. The presence or the absence of these genes confirms that tested strains are resistant to specific antibiotic or not. Bacteria pathogenic activity was emphasized by genes as follows: sea (enterotoxin which was found at all isolates, tst (toxic shock toxin gene was not detected in any of isolates and tuf gene (elongation factor was obtained with one pair of primers. Resistance to beta-lactams was evidenced by the presence of mecA in all isolates and femA in some strains. Each of ermC, ermA and ermB, macrolides-lincosamides-streptogramin B resistance genes, were detected.

New Technologies for Rapid Bacterial Identification and Antibiotic Resistance Profiling.

Science.gov (United States)

Kelley, Shana O

2017-04-01

Conventional approaches to bacterial identification and drug susceptibility testing typically rely on culture-based approaches that take 2 to 7 days to return results. The long turnaround times contribute to the spread of infectious disease, negative patient outcomes, and the misuse of antibiotics that can contribute to antibiotic resistance. To provide new solutions enabling faster bacterial analysis, a variety of approaches are under development that leverage single-cell analysis, microfluidic concentration and detection strategies, and ultrasensitive readout mechanisms. This review discusses recent advances in this area and the potential of new technologies to enable more effective management of infectious disease.

New antimicrobial contact catalyst killing antibiotic resistant clinical and waterborne pathogens

Energy Technology Data Exchange (ETDEWEB)

Guridi, A. [Biophysics Unit (CSIC, UPV/EHU), Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa (Spain); Diederich, A.-K. [University Medical Center Freiburg, Division of Infectious Diseases, Hugstetter Strasse 55, 79106 Freiburg (Germany); Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Schänzlestrasse 1, 79104 Freiburg (Germany); Aguila-Arcos, S.; Garcia-Moreno, M. [Biophysics Unit (CSIC, UPV/EHU), Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa (Spain); Blasi, R.; Broszat, M. [University Medical Center Freiburg, Division of Infectious Diseases, Hugstetter Strasse 55, 79106 Freiburg (Germany); Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Schänzlestrasse 1, 79104 Freiburg (Germany); Schmieder, W.; Clauss-Lendzian, E. [Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Schänzlestrasse 1, 79104 Freiburg (Germany); Sakinc-Gueler, T. [University Medical Center Freiburg, Division of Infectious Diseases, Hugstetter Strasse 55, 79106 Freiburg (Germany); Andrade, R. [Advanced Research Facilities (SGIker), University of the Basque Country, UPV/EHU, 48940 Leioa (Spain); Alkorta, I. [Biophysics Unit (CSIC, UPV/EHU), Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa (Spain); Meyer, C.; Landau, U. [Largentec GmbH, Am Waldhaus 32, 14129 Berlin (Germany); Grohmann, E., E-mail: elisabeth.grohmann@googlemail.com [Biophysics Unit (CSIC, UPV/EHU), Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa (Spain); University Medical Center Freiburg, Division of Infectious Diseases, Hugstetter Strasse 55, 79106 Freiburg (Germany); Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Schänzlestrasse 1, 79104 Freiburg (Germany)

2015-05-01

Microbial growth on medical and technical devices is a big health issue, particularly when microorganisms aggregate to form biofilms. Moreover, the occurrence of antibiotic-resistant bacteria in the clinical environment is dramatically growing, making treatment of bacterial infections very challenging. In search of an alternative, we studied a novel antimicrobial surface coating based on micro galvanic elements formed by silver and ruthenium with surface catalytic properties. The antimicrobial coating efficiently inhibited the growth of the nosocomial pathogens Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Enterococcus faecium as demonstrated by the growth inhibition on agar surface and in biofilms of antibiotic resistant clinical E. faecalis, E. faecium, and S. aureus isolates. It also strongly reduced the growth of Legionella in a drinking water pipeline and of Escherichia coli in urine. We postulate a mode of action of the antimicrobial material, which is independent of the release of silver ions. Thus, the novel antimicrobial coating could represent an alternative to combat microbial growth avoiding the toxic side effects of high levels of silver ions on eukaryotic cells. - Highlights: • The novel antimicrobial inhibits growth of clinical staphylococci and enterococci. • The novel antimicrobial inhibits growth of Legionella in drinking water. • A putative mode of action of the antimicrobial coating is presented.

New antimicrobial contact catalyst killing antibiotic resistant clinical and waterborne pathogens

International Nuclear Information System (INIS)

Guridi, A.; Diederich, A.-K.; Aguila-Arcos, S.; Garcia-Moreno, M.; Blasi, R.; Broszat, M.; Schmieder, W.; Clauss-Lendzian, E.; Sakinc-Gueler, T.; Andrade, R.; Alkorta, I.; Meyer, C.; Landau, U.; Grohmann, E.

2015-01-01

Microbial growth on medical and technical devices is a big health issue, particularly when microorganisms aggregate to form biofilms. Moreover, the occurrence of antibiotic-resistant bacteria in the clinical environment is dramatically growing, making treatment of bacterial infections very challenging. In search of an alternative, we studied a novel antimicrobial surface coating based on micro galvanic elements formed by silver and ruthenium with surface catalytic properties. The antimicrobial coating efficiently inhibited the growth of the nosocomial pathogens Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Enterococcus faecium as demonstrated by the growth inhibition on agar surface and in biofilms of antibiotic resistant clinical E. faecalis, E. faecium, and S. aureus isolates. It also strongly reduced the growth of Legionella in a drinking water pipeline and of Escherichia coli in urine. We postulate a mode of action of the antimicrobial material, which is independent of the release of silver ions. Thus, the novel antimicrobial coating could represent an alternative to combat microbial growth avoiding the toxic side effects of high levels of silver ions on eukaryotic cells. - Highlights: • The novel antimicrobial inhibits growth of clinical staphylococci and enterococci. • The novel antimicrobial inhibits growth of Legionella in drinking water. • A putative mode of action of the antimicrobial coating is presented

Antibiotic resistance profile of bacterial isolates from food sold on a ...

African Journals Online (AJOL)

The antibiotic resistance profile of bacterial isolates from cooked food samples sold in different eateries on the campus of the University of Ado-Ekiti was investigated. A total of seventy-eight bacterial isolates belonging to six genera were encountered in the following proportion: Escherichia coli (29.5%), Klebsiella spp.

Genetic Regulation of Virulence and Antibiotic Resistance in Acinetobacter baumannii

Science.gov (United States)

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

2016-01-01

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

Disruption of the Gut Microbiome: Clostridium difficile Infection and the Threat of Antibiotic Resistance

Directory of Open Access Journals (Sweden)

Priscilla A. Johanesen

2015-12-01

Full Text Available Clostridium difficile is well recognized as the leading cause of antibiotic-associated diarrhea, having a significant impact in both health-care and community settings. Central to predisposition to C. difficile infection is disruption of the gut microbiome by antibiotics. Being a Gram-positive anaerobe, C. difficile is intrinsically resistant to a number of antibiotics. Mobile elements encoding antibiotic resistance determinants have also been characterized in this pathogen. While resistance to antibiotics currently used to treat C. difficile infection has not yet been detected, it may be only a matter of time before this occurs, as has been seen with other bacterial pathogens. This review will discuss C. difficile disease pathogenesis, the impact of antibiotic use on inducing disease susceptibility, and the role of antibiotic resistance and mobile elements in C. difficile epidemiology.

The multifaceted roles of antibiotics and antibiotic resistance in nature

Directory of Open Access Journals (Sweden)

Saswati eSengupta

2013-03-01

Full Text Available Antibiotics are chemotherapeutic agents, which have been a very powerful tool in the clinical management of bacterial diseases since the 1940s. However, benefits offered by these magic bullets have been substantially lost in subsequent days following the widespread emergence and dissemination of antibiotic resistant strains. While it is obvious that excessive and imprudent use of antibiotics significantly contributes to the emergence of resistant strains, antibiotic-resistance is also observed in natural bacteria of remote places unlikely to be impacted by human intervention. Both antibiotic biosynthetic genes and resistance-conferring genes have been known to evolve billions of years ago, long before clinical use of antibiotics. Hence it appears that antibiotics and antibiotics resistance determinants have some other roles in nature, which often elude our attention because of overemphasis on the therapeutic importance of antibiotics and the crisis imposed by the antibiotic-resistance in pathogens. In the natural milieu, antibiotics are often found to be present in subinhibitory concentrations acting as signalling molecules supporting quorum sensing and biofilm formation. They also play an important role in the production of virulence factors and influence host-parasite interactions (e.g., phagocytosis, adherence to the target cell and so on. The evolutionary and ecological aspects of antibiotics and antibiotic-resistance in the naturally occurring microbial community are little understood. Therefore, the actual role of antibiotics in nature warrants in-depth investigations. Studies on such an intriguing behaviour of the microorganisms promise insight into the intricacies of the microbial physiology and are likely to provide some lead in controlling the emergence and subsequent dissemination of antibiotic resistance. This article highlights some of the recent findings on the role of antibiotics and genes that confer resistance to antibiotics in

Cysteamine-mediated clearance of antibiotic-resistant pathogens in human cystic fibrosis macrophages.

Directory of Open Access Journals (Sweden)

Chandra L Shrestha

Full Text Available Members of the Burkholderia cepacia complex are virulent, multi-drug resistant pathogens that survive and replicate intracellularly in patients with cystic fibrosis (CF. We have discovered that B. cenocepacia cannot be cleared from CF macrophages due to defective autophagy, causing continued systemic inflammation and infection. Defective autophagy in CF is mediated through constitutive reactive oxygen species (ROS activation of transglutaminase-2 (TG2, which causes the sequestration (accumulation of essential autophagy initiating proteins. Cysteamine is a TG2 inhibitor and proteostasis regulator with the potential to restore autophagy. Therefore, we sought to examine the impact of cysteamine on CF macrophage autophagy and bacterial killing. Human peripheral blood monocyte-derived macrophages (MDMs and alveolar macrophages were isolated from CF and non-CF donors. Macrophages were infected with clinical isolates of relevant CF pathogens. Cysteamine caused direct bacterial growth killing of live B. cenocepacia, B. multivorans, P. aeruginosa and MRSA in the absence of cells. Additionally, B. cenocepacia, B. multivorans, and P. aeruginosa invasion were significantly decreased in CF MDMs treated with cysteamine. Finally, cysteamine decreased TG2, p62, and beclin-1 accumulation in CF, leading to increased Burkholderia uptake into autophagosomes, increased macrophage CFTR expression, and decreased ROS and IL-1β production. Cysteamine has direct anti-bacterial growth killing and improves human CF macrophage autophagy resulting in increased macrophage-mediated bacterial clearance, decreased inflammation, and reduced constitutive ROS production. Thus, cysteamine may be an effective adjunct to antibiotic regimens in CF.

Absence of bacterial resistance following repeat exposure to photodynamic therapy

Science.gov (United States)

Pedigo, Lisa A.; Gibbs, Aaron J.; Scott, Robert J.; Street, Cale N.

2009-06-01

The prevalence of antibiotic resistant bacteria necessitates exploration of alternative approaches to treat hospital and community acquired infections. The aim of this study was to determine whether bacterial pathogens develop resistance to antimicrobial photodynamic therapy (aPDT) during repeated sub-lethal challenge. Antibiotic sensitive and resistant strains of S. aureus and antibiotic sensitive E. coli were subjected to repeat PDT treatments using a methylene blue photosensitizer formulation and 670 nm illumination from a non-thermal diode laser. Parameters were adjusted such that kills were antibiotic resistance strains. Furthermore, repeated sub-lethal exposure does not induce resistance to subsequent PDT treatments. The absence of resistance formation represents a significant advantage of PDT over traditional antibiotics.

A model of antibiotic-resistant bacterial epidemics in hospitals

OpenAIRE

Webb, Glenn F.; D'Agata, Erika M. C.; Magal, Pierre; Ruan, Shigui

2005-01-01

The emergence of drug-resistant strains of bacteria is an increasing threat to society, especially in hospital settings. Many antibiotics that were formerly effective in combating bacterial infections in hospital patients are no longer effective because of the evolution of resistant strains, which compromises medical care worldwide. In this article, we formulate a two-level population model to quantify key elements in nosocomial (hospital-acquired) infections. At the bacteria level, patients ...

Encyclopedia of bacterial gene circuits whose presence or absence correlate with pathogenicity--a large-scale system analysis of decoded bacterial genomes.

Science.gov (United States)

Shestov, Maksim; Ontañón, Santiago; Tozeren, Aydin

2015-10-13

Bacterial infections comprise a global health challenge as the incidences of antibiotic resistance increase. Pathogenic potential of bacteria has been shown to be context dependent, varying in response to environment and even within the strains of the same genus. We used the KEGG repository and extensive literature searches to identify among the 2527 bacterial genomes in the literature those implicated as pathogenic to the host, including those which show pathogenicity in a context dependent manner. Using data on the gene contents of these genomes, we identified sets of genes highly abundant in pathogenic but relatively absent in commensal strains and vice versa. In addition, we carried out genome comparison within a genus for the seventeen largest genera in our genome collection. We projected the resultant lists of ortholog genes onto KEGG bacterial pathways to identify clusters and circuits, which can be linked to either pathogenicity or synergy. Gene circuits relatively abundant in nonpathogenic bacteria often mediated biosynthesis of antibiotics. Other synergy-linked circuits reduced drug-induced toxicity. Pathogen-abundant gene circuits included modules in one-carbon folate, two-component system, type-3 secretion system, and peptidoglycan biosynthesis. Antibiotics-resistant bacterial strains possessed genes modulating phagocytosis, vesicle trafficking, cytoskeletal reorganization, and regulation of the inflammatory response. Our study also identified bacterial genera containing a circuit, elements of which were previously linked to Alzheimer's disease. Present study produces for the first time, a signature, in the form of a robust list of gene circuitry whose presence or absence could potentially define the pathogenicity of a microbiome. Extensive literature search substantiated a bulk majority of the commensal and pathogenic circuitry in our predicted list. Scanning microbiome libraries for these circuitry motifs will provide further insights into the complex

Antibacterial screening of traditional herbal plants and standard antibiotics against some human bacterial pathogens.

Science.gov (United States)

Awan, Uzma Azeem; Andleeb, Saiqa; Kiyani, Ayesha; Zafar, Atiya; Shafique, Irsa; Riaz, Nazia; Azhar, Muhammad Tehseen; Uddin, Hafeez

2013-11-01

Chloroformic and isoamyl alcohol extracts of Cinnnamomum zylanicum, Cuminum cyminum, Curcuma long Linn, Trachyspermum ammi and selected standard antibiotics were investigated for their in vitro antibacterial activity against six human bacterial pathogens. The antibacterial activity was evaluated and based on the zone of inhibition using agar disc diffusion method. The tested bacterial strains were Streptococcus pyogenes, Staphylococcus epidermidis, Klebsiella pneumonia, Staphylococcus aurues, Serratia marcesnces, and Pseudomonas aeruginosa. Ciprofloxacin showed highly significant action against K. pneumonia and S. epidermidis while Ampicillin and Amoxicillin indicated lowest antibacterial activity against tested pathogens. Among the plants chloroform and isoamyl alcohol extracts of C. cyminum, S. aromaticum and C. long Linn had significant effect against P. aeruginosa, S. marcesnces and S. pyogenes. Comparison of antibacterial activity of medicinal herbs and standard antibiotics was also recorded via activity index. Used medicinal plants have various phytochemicals which reasonably justify their use as antibacterial agent.

Pharmacological Targeting of the Host-Pathogen Interaction: Alternatives to Classical Antibiotics to Combat Drug-Resistant Superbugs.

Science.gov (United States)

Munguia, Jason; Nizet, Victor

2017-05-01

The rise of multidrug-resistant pathogens and the dearth of new antibiotic development place an existential strain on successful infectious disease therapy. Breakthrough strategies that go beyond classical antibiotic mechanisms are needed to combat this looming public health catastrophe. Reconceptualizing antibiotic therapy in the richer context of the host-pathogen interaction is required for innovative solutions. By defining specific virulence factors, the essence of a pathogen, and pharmacologically neutralizing their activities, one can block disease progression and sensitize microbes to immune clearance. Likewise, host-directed strategies to boost phagocyte bactericidal activity, enhance leukocyte recruitment, or reverse pathogen-induced immunosuppression seek to replicate the success of cancer immunotherapy in the field of infectious diseases. The answer to the threat of multidrug-resistant pathogens lies 'outside the box' of current antibiotic paradigms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sequencing of Bacterial Genomes: Principles and Insights into Pathogenesis and Development of Antibiotics

Directory of Open Access Journals (Sweden)

Eric S. Donkor

2013-10-01

Full Text Available The impact of bacterial diseases on public health has become enormous, and is partly due to the increasing trend of antibiotic resistance displayed by bacterial pathogens. Sequencing of bacterial genomes has significantly improved our understanding about the biology of many bacterial pathogens as well as identification of novel antibiotic targets. Since the advent of genome sequencing two decades ago, about 1,800 bacterial genomes have been fully sequenced and these include important aetiological agents such as Streptococcus pneumoniae, Mycobacterium tuberculosis, Escherichia coli O157:H7, Vibrio cholerae, Clostridium difficile and Staphylococcus aureus. Very recently, there has been an explosion of bacterial genome data and is due to the development of next generation sequencing technologies, which are evolving so rapidly. Indeed, the field of microbial genomics is advancing at a very fast rate and it is difficult for researchers to be abreast with the new developments. This highlights the need for regular updates in microbial genomics through comprehensive reviews. This review paper seeks to provide an update on bacterial genome sequencing generally, and to analyze insights gained from sequencing in two areas, including bacterial pathogenesis and the development of antibiotics.

[Bacterial efflux pumps - their role in antibiotic resistance and potential inhibitors].

Science.gov (United States)

Hricová, Kristýna; Kolář, Milan

2014-12-01

Efflux pumps capable of actively draining antibiotic agents from bacterial cells may be considered one of potential mechanisms of the development of antimicrobial resistance. The most important group of efflux pumps capable of removing several types of antibiotics include RND (resistance - nodulation - division) pumps. These are three proteins that cross the bacterial cell wall, allowing direct expulsion of the agent out from the bacterial cell. The most investigated efflux pumps are the AcrAB-TolC system in Escherichia coli and the MexAB-OprM system in Pseudomonas aeruginosa. Moreover, efflux pumps are able to export other than antibacterial agents such as disinfectants, thus decreasing their effectiveness. One potential approach to inactivation of an efflux pump is to use the so-called efflux pump inhibitors (EPIs). Potential inhibitors tested in vitro involve, for example, phenylalanyl-arginyl-b-naphthylamide (PAbN), carbonyl cyanide m-chlorophenylhydrazone (CCCP) or agents of the phenothiazine class.

[Antibiotic resistance--an ambivalence of attitudes. As of now, the bacteria are in advantage].

Science.gov (United States)

Sköld, O

1995-09-13

The value of the precious medical asset that antibiotics constitute is contimualby being eroded by the spread of resistance. For some time that bacterial world has been adapting itself to contend with the toxic assault of man-made poisons, antibiotics, by developing resistance in a very rapid process of evolutionary changes occurring before our very eyes. This evolutionary adaptation is an example of natural genetic engineering entailing an interchange between bacteria of genes conferring antibiotic resistance. Trimethoprim resistance is an example where numerous genes of unknown origin (some closely interrelated), expressing drug-resistant dihydrofolate reductases, move among human commensals and pathogens. They have been shown to move as gene cassettes in and out of the recently characterised integron structure occurring in many pathogens. They are also carried by various transposons such as Tn7, or Tn5393 originally observed in a plant pathogen, Erwinia amylovora. Betalactam resistance is another example of natural genetic engineering, where new betalactamases are continually emerging, and individual enzyme substrate specificity is modified by point mutation. At present, betalactamase mutants resistant to all commercially available betalactams, including clavulanic acid used in combination with betalactam antibiotics, are to be found in clinical isolates. Thus, currently bacteria seem to be triumphing in the running battle between the pharmaceutical industry and the bacterial world, the former introducing one new antibiotic variant after another, to which bacteria promptly develop resistance by manipulating their own genomes.

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

Directory of Open Access Journals (Sweden)

Wen Shan Yew

2013-08-01

Full Text Available Quorum sensing is a cell density-dependent signaling phenomenon used by bacteria for coordination of population-wide phenotypes, such as expression of virulence genes, antibiotic resistance and biofilm formation. Lately, disruption of bacterial communication has emerged as an anti-virulence strategy with enormous therapeutic potential given the increasing incidences of drug resistance in pathogenic bacteria. The quorum quenching therapeutic approach promises a lower risk of resistance development, since interference with virulence generally does not affect the growth and fitness of the bacteria and, hence, does not exert an associated selection pressure for drug-resistant strains. With better understanding of bacterial communication networks and mechanisms, many quorum quenching methods have been developed against various clinically significant bacterial pathogens. In particular, Gram-negative bacteria are an important group of pathogens, because, collectively, they are responsible for the majority of hospital-acquired infections. Here, we discuss the current understanding of existing quorum sensing mechanisms and present important inhibitory strategies that have been developed against this group of pathogenic bacteria.

PREVALENCE AND ANTIBIOTIC RESISTANCE OF FOOD BORNE BACTERIAL CONTAMINATION IN SOME EGYPTIAN FOOD food

Directory of Open Access Journals (Sweden)

Samy Selim

2015-09-01

Full Text Available This study was undertaken to investigate the prevalence and antibiotic resistance of food borne bacterial contamination in some Egyptian food. Total viable bacteria and total coliform bacteriawere isolated from different sources of food; carbohydrates (bread, flour and basbousa, vegetables (outer and inner tissues of potato and outer and inner tissues of cucumber and proteins (mincedmeat, cheese and milk. The study resulted in maximum value of total viable bacteria found in outer tissue of potato 68X104±1.0, while the minimum value found in inner tissues of potato andcucumber. The study resulted in total coliform was maximum value in minced meat 6.4X103±0.3. Basbousa and inner tissue of potato and cucumber were free from coliforms. The ability of isolatesto producing proteolytic enzymes was tested, we found that 326 isolate (63.92% from all isolates had this ability, thus we selected most 2 potent proteolytic isolates. The two isolates were identifiedas Bacillus cereus and Escherichia coli. The identification confirmed by microlog 34.20 system and 16SrRNA for two isolates and the same result was founded. Sensitivity tested for the most potentproteolytic species to 12 of the most commonly used antibiotics in the Egyptian pharmacy. The results showed that all species were sensitive to most of antibiotics, except B. cereus which was strongly susceptible to azteronam and ceftazidim. The data showed that raw meat, cooked food products, and raw milk were most commonly contaminated with foodborne pathogens and many pathogens were resistant to different antibiotics. The study provided useful information for assessment of the possible risk posed to consumers, which has significant public health impact.

[Antibiotic resistance: A global crisis].

Science.gov (United States)

Alós, Juan-Ignacio

2015-12-01

The introduction of antibiotics into clinical practice represented one of the most important interventions for the control of infectious diseases. Antibiotics have saved millions of lives and have also brought a revolution in medicine. However, an increasing threat has deteriorated the effectiveness of these drugs, that of bacterial resistance to antibiotics, which is defined here as the ability of bacteria to survive in antibiotic concentrations that inhibit/kill others of the same species. In this review some recent and important examples of resistance in pathogens of concern for mankind are mentioned. It is explained, according to present knowledge, the process that led to the current situation in a short time, evolutionarily speaking. It begins with the resistance genes, continues with clones and genetic elements involved in the maintenance and dissemination, and ends with other factors that contribute to its spread. Possible responses to the problem are also reviewed, with special reference to the development of new antibiotics. Copyright © 2014 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Antibiotic resistance of Streptococcus pneumoniae in children with acute otitis media treatment failure.

Science.gov (United States)

Zielnik-Jurkiewicz, Beata; Bielicka, Anna

2015-12-01

The emergence of antibiotic-resistant bacteria is a major cause of treatment failure in children with acute otitis media (AOM). This study aimed to analyze the types of bacterial strains in fluid isolated from the middle ear of children with AOM who did not respond to oral antibiotic treatment. We also determined the antibiotic resistance of the most frequently isolated bacterial strain (Streptococcus pneumoniae) found in these children. This was a prospective study of 157 children with AOM aged from 6 months to 7 years admitted due to unsuccessful oral antibiotic treatment. All children underwent a myringotomy, and samples of the middle ear fluid were collected for bacteriological examination. Positive bacterial cultures were obtained in 104 patients (66.2%), with Streptococcus pneumoniae (39.69%), Haemophilus influenzae (16.03%) Staphylococcus aureus (16.03%), Staphylococcus haemolyticus (6.9%) and Streptococcus pyogenes (5.34%) found most frequently. The majority (65.4%) of S. pneumoniae strains were penicillin-intermediate-resistant or penicillin-resistant, and 67.2% strains of S. pneumoniae were multidrug-resistant. We identified S. pneumoniae as the most frequently isolated pathogen from the middle ear in children with AOM treatment failure and determined that the majority of strains were antibiotic-resistant. We propose that the microbiological identification of bacterial strains and their degree of antibiotic resistance should be performed prior to therapy in order to choose the most appropriate antibiotic therapy for children with AOM treatment failure. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Potentiating antibiotics in drug-resistant clinical isolates via stimuli-activated superoxide generation.

Science.gov (United States)

Courtney, Colleen M; Goodman, Samuel M; Nagy, Toni A; Levy, Max; Bhusal, Pallavi; Madinger, Nancy E; Detweiler, Corrella S; Nagpal, Prashant; Chatterjee, Anushree

2017-10-01

The rise of multidrug-resistant (MDR) bacteria is a growing concern to global health and is exacerbated by the lack of new antibiotics. To treat already pervasive MDR infections, new classes of antibiotics or antibiotic adjuvants are needed. Reactive oxygen species (ROS) have been shown to play a role during antibacterial action; however, it is not yet understood whether ROS contribute directly to or are an outcome of bacterial lethality caused by antibiotics. We show that a light-activated nanoparticle, designed to produce tunable flux of specific ROS, superoxide, potentiates the activity of antibiotics in clinical MDR isolates of Escherichia coli , Salmonella enterica , and Klebsiella pneumoniae . Despite the high degree of antibiotic resistance in these isolates, we observed a synergistic interaction between both bactericidal and bacteriostatic antibiotics with varied mechanisms of action and our superoxide-producing nanoparticles in more than 75% of combinations. As a result of this potentiation, the effective antibiotic concentration of the clinical isolates was reduced up to 1000-fold below their respective sensitive/resistant breakpoint. Further, superoxide-generating nanoparticles in combination with ciprofloxacin reduced bacterial load in epithelial cells infected with S. enterica serovar Typhimurium and increased Caenorhabditis elegans survival upon infection with S. enterica serovar Enteriditis, compared to antibiotic alone. This demonstration highlights the ability to engineer superoxide generation to potentiate antibiotic activity and combat highly drug-resistant bacterial pathogens.

The importance of lag time extension in determining bacterial resistance to\\ud antibiotics

OpenAIRE

Li, Bing; Qiu, Yong; Shi, Hanchang; Yin, Huabing

2016-01-01

It is widely appreciated that widespread antibiotic resistance has significantly reduced the utility of today’s antibiotics. Many antibiotics now fail to cure infectious diseases, although they are classified as effective bactericidal agents based on antibiotic susceptibility tests. Here, via kinetic growth assays, we evaluated the effects of 12 commonly used antibiotics on the lag phase of a range of pure environmental isolates and sludge bacterial communities of high diversity. We show that...

Detection of antibiotic resistance in clinical bacterial strains from pets

OpenAIRE

Poeta, P.; Rodrigues, J.

2008-01-01

The identification of different bacterial strains and the occurrence of antibiotic resistance were investigated in several infection processes of pets as skin abscess with purulent discharge, bronco alveolar fluid, earwax, urine, mammary, and eye fluid. Streptococcus spp. and Staphylococcus spp. were the most detected in the different samples. A high frequency of antimicrobial resistance has been observed and this could reflect the wide use of antimicrobials in pets, making the effectiveness ...

Antibiotic resistance reservoirs

NARCIS (Netherlands)

Versluis, Dennis

2016-01-01

One of the major threats to human health in the 21st century is the emergence of pathogenic bacteria that are resistant to multiple antibiotics, thereby limiting treatment options. An important route through which pathogens become resistant is via acquisition of resistance genes from

Prevalence of antibiotic resistance genes in the bacterial flora of integrated fish farming environments of Pakistan and Tanzania.

Science.gov (United States)

Shah, Syed Q A; Colquhoun, Duncan J; Nikuli, Hamisi L; Sørum, Henning

2012-08-21

The use of a wide variety of antimicrobials in human and veterinary medicine, including aquaculture, has led to the emergence of antibiotic resistant pathogens. In the present study, bacteria from water, sediments, and fish were collected from fish farms in Pakistan and Tanzania with no recorded history of antibiotic use. The isolates were screened for the presence of resistance genes against various antimicrobials used in aquaculture and animal husbandry. Resistant isolates selected by disk diffusion and genotyped by Southern hybridization were further screened by polymerase chain reaction (PCR) and amplicon sequencing. The prominent resistance genes identified encoded tetracycline [tetA(A) and tetA(G)], trimethoprim [dfrA1, dfrA5, dfrA7, dfrA12, and dfrA15], amoxicillin [bla(TEM)], streptomycin [strA-strB], chloramphenicol [cat-1], and erythromycin resistance [mefA]. The int1 gene was found in more than 30% of the bacterial isolates in association with gene cassettes. MAR indices ranged from 0.2 to 1. The bla(NDM-1) gene was not identified in ertapenem resistant isolates. It is hypothesized that integrated fish farming practices utilizing domestic farm and poultry waste along with antibiotic residues from animal husbandry may have contributed to a pool of resistance genes in the aquaculture systems studied.

Antibiotic resistance increases with local temperature

Science.gov (United States)

MacFadden, Derek R.; McGough, Sarah F.; Fisman, David; Santillana, Mauricio; Brownstein, John S.

2018-06-01

Bacteria that cause infections in humans can develop or acquire resistance to antibiotics commonly used against them1,2. Antimicrobial resistance (in bacteria and other microbes) causes significant morbidity worldwide, and some estimates indicate the attributable mortality could reach up to 10 million by 20502-4. Antibiotic resistance in bacteria is believed to develop largely under the selective pressure of antibiotic use; however, other factors may contribute to population level increases in antibiotic resistance1,2. We explored the role of climate (temperature) and additional factors on the distribution of antibiotic resistance across the United States, and here we show that increasing local temperature as well as population density are associated with increasing antibiotic resistance (percent resistant) in common pathogens. We found that an increase in temperature of 10 °C across regions was associated with an increases in antibiotic resistance of 4.2%, 2.2%, and 2.7% for the common pathogens Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. The associations between temperature and antibiotic resistance in this ecological study are consistent across most classes of antibiotics and pathogens and may be strengthening over time. These findings suggest that current forecasts of the burden of antibiotic resistance could be significant underestimates in the face of a growing population and climate change4.

Can Clays in Livestock Feed Promote Antibiotic Resistance and Virulence in Pathogenic Bacteria?

Directory of Open Access Journals (Sweden)

Alexandro Rodríguez-Rojas

2015-07-01

Full Text Available The use of antibiotics in animal husbandry has long been associated with the appearance of antibiotic resistance and virulence factor determinants. Nonetheless, the number of cases of human infection involving resistant or virulent microorganisms that originate in farms is increasing. While many antibiotics have been banned as dietary supplements in some countries, other additives thought to be innocuous in terms of the development and spread of antibiotic resistance are used as growth promoters. In fact, several clay materials are routinely added to animal feed with the aim of improving growth and animal product quality. However, recent findings suggest that sepiolite, a clay additive, mediates the direct transfer of plasmids between different bacterial species. We therefore hypothesize that clays present in animal feed facilitate the horizontal transfer of resistance determinants in the digestive tract of farm animals.

Conjunctival bacterial flora and antibiotic resistance pattern in patients undergoing cataract surgery

Directory of Open Access Journals (Sweden)

Arantes Tiago Eugênio Faria e

2006-01-01

Full Text Available PURPOSE: To evaluate the conjunctival bacterial flora and its antibiotic resistance pattern in eyes of patients undergoing cataract surgery. METHODS: From August to October 2004, 50 patients undergoing cataract surgery in the "Fundação Altino Ventura", Recife, Brazil, were prospectively evaluated. Conjunctival material was obtained on the day of surgery, before the application of topical anesthetic, antibiotic or povidone-iodine. The collected material was inoculated and bacterioscopic analysis was carried out. In the cases where there was bacterial growth, antibiotic susceptibility tests and cultures, for isolation and identification of the bacteria, were performed. RESULTS: Of the 50 eyes, 43 (86.0% had positive cultures. The coagulase-negative Staphylococcus (CNS, found in 27 (54.0% eyes, was the most frequent organism. More than 90% of the isolates of this bacterium were susceptible to cephalotin, vancomycin, chloramphenicol, ofloxacin and gatifloxacin; 70 to 90% were susceptible to gentamicin, cefotaxime, oxacillin and ciprofloxacin; and less than 70% were sensible to neomycin. Four (10.5% of the bacterial isolates were resistant to four or more antibiotics, two of them were CNS. CONCLUSION: The most frequent bacterium in the conjunctival flora is the coagulase-negative Staphylococcus. The isolates of this organism showed low susceptibility rate to neomycin, and high susceptibility rates to cephalotin, vancomycin, chloramphenicol, ofloxacin and gatifloxacin.

Co-Selection of Resistance to Antibiotics, Biocides and Heavy Metals, and Its Relevance to Foodborne Pathogens

Directory of Open Access Journals (Sweden)

Andrew D. Wales

2015-11-01

Full Text Available Concerns have been raised in recent years regarding co-selection for antibiotic resistance among bacteria exposed to biocides used as disinfectants, antiseptics and preservatives, and to heavy metals (particularly copper and zinc used as growth promoters and therapeutic agents for some livestock species. There is indeed experimental and observational evidence that exposure to these non-antibiotic antimicrobial agents can induce or select for bacterial adaptations that result in decreased susceptibility to one or more antibiotics. This may occur via cellular mechanisms that are protective across multiple classes of antimicrobial agents or by selection of genetic determinants for resistance to non-antibiotic agents that are linked to genes for antibiotic resistance. There may also be relevant effects of these antimicrobial agents on bacterial community structure and via non-specific mechanisms such as mobilization of genetic elements or mutagenesis. Notably, some co-selective adaptations have adverse effects on fitness in the absence of a continued selective pressure. The present review examines the evidence for the significance of these phenomena, particularly in respect of bacterial zoonotic agents that commonly occur in livestock and that may be transmitted, directly or via the food chain, to human populations.

The agricultural use of water treatment plant sludge: pathogens and antibiotic resistance

Directory of Open Access Journals (Sweden)

Ignacio Nadal Rocamora

2015-12-01

Full Text Available The use of water treatment plant sludge to restore degraded soils is customary agricultural practice, but it could be dangerous from the point of view of both health and the environment. A transient increase of either pathogenic or indicator microbial populations, whose persistence in time is variable and attributed to the characteristics of the soil (types of materials in the soil, any amendments (origin and treatments it has undergone or the weather (humidity and temperature mainly, has often been detected in soils treated with this kind of waste. Given their origin, water treatment plant sludges could lead to the transmission of a pathogens and b antibiotic-resistant microorganisms to human beings through the food chain and cause the spreading of antibiotic resistances as a result of their increase and persistence in the soil for variable periods of time. However, Spanish legislation regulating the use of sludges in the farming industry is based on a very restricted microbiological criterion. Thus, we believe better parameters should be established to appropriately inform of the state of health of soils treated with water treatment plant sludge, including aspects which are not presently assessed such as antibiotic resistance.

Toward repurposing ciclopirox as an antibiotic against drug-resistant Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae.

Science.gov (United States)

Carlson-Banning, Kimberly M; Chou, Andrew; Liu, Zhen; Hamill, Richard J; Song, Yongcheng; Zechiedrich, Lynn

2013-01-01

Antibiotic-resistant infections caused by gram-negative bacteria are a major healthcare concern. Repurposing drugs circumvents the time and money limitations associated with developing new antimicrobial agents needed to combat these antibiotic-resistant infections. Here we identified the off-patent antifungal agent, ciclopirox, as a candidate to repurpose for antibiotic use. To test the efficacy of ciclopirox against antibiotic-resistant pathogens, we used a curated collection of Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae clinical isolates that are representative of known antibiotic resistance phenotypes. We found that ciclopirox, at 5-15 µg/ml concentrations, inhibited bacterial growth regardless of the antibiotic resistance status. At these same concentrations, ciclopirox reduced growth of Pseudomonas aeruginosa clinical isolates, but some of these pathogens required higher ciclopirox concentrations to completely block growth. To determine how ciclopirox inhibits bacterial growth, we performed an overexpression screen in E. coli. This screen revealed that galE, which encodes UDP-glucose 4-epimerase, rescued bacterial growth at otherwise restrictive ciclopirox concentrations. We found that ciclopirox does not inhibit epimerization of UDP-galactose by purified E. coli GalE; however, ΔgalU, ΔgalE, ΔrfaI, or ΔrfaB mutant strains all have lower ciclopirox minimum inhibitory concentrations than the parent strain. The galU, galE, rfaI, and rfaB genes all encode enzymes that use UDP-galactose or UDP-glucose for galactose metabolism and lipopolysaccharide (LPS) biosynthesis. Indeed, we found that ciclopirox altered LPS composition of an E. coli clinical isolate. Taken together, our data demonstrate that ciclopirox affects galactose metabolism and LPS biosynthesis, two pathways important for bacterial growth and virulence. The lack of any reported fungal resistance to ciclopirox in over twenty years of use in the clinic, its excellent safety

Pathogen- and Host-Directed Anti-Inflammatory Activities of Macrolide Antibiotics

OpenAIRE

Steel, Helen C.; Theron, Annette J.; Cockeran, Riana; Anderson, Ronald; Feldman, Charles

2012-01-01

Macrolide antibiotics possess several, beneficial, secondary properties which complement their primary antimicrobial activity. In addition to high levels of tissue penetration, which may counteract seemingly macrolide-resistant bacterial pathogens, these agents also possess anti-inflammatory properties, unrelated to their primary antimicrobial activity. Macrolides target cells of both the innate and adaptive immune systems, as well as structural cells, and are beneficial in controlling harmfu...

Fighting infections due to multidrug-resistant Gram-positive pathogens.

Science.gov (United States)

Cornaglia, G

2009-03-01

Growing bacterial resistance in Gram-positive pathogens means that what were once effective and inexpensive treatments for infections caused by these bacteria are now being seriously questioned, including penicillin and macrolides for use against pneumococcal infections and-in hospitals-oxacillin for use against staphylococcal infections. As a whole, multidrug-resistant (MDR) Gram-positive pathogens are rapidly becoming an urgent and sometimes unmanageable clinical problem. Nevertheless, and despite decades of research into the effects of antibiotics, the actual risk posed to human health by antibiotic resistance has been poorly defined; the lack of reliable data concerning the outcomes resulting from antimicrobial resistance stems, in part, from problems with study designs and the methods used in resistence determination. Surprisingly little is known, too, about the actual effectiveness of the many types of intervention aimed at controlling antibiotic resistance. New antibiotics active against MDR Gram-positive pathogens have been recently introduced into clinical practice, and the antibiotic pipeline contains additional compounds at an advanced stage of development, including new glycopeptides, new anti-methicillin-resistant Staphylococcus aureus (MRSA) beta-lactams, and new diaminopyrimidines. Many novel antimicrobial agents are likely to be niche products, endowed with narrow antibacterial spectra and/or targeted at specific clinical problems. Therefore, an important educational goal will be to change the current, long-lasting attitudes of both physicians and customers towards broad-spectrum and multipurpose compounds. Scientific societies, such as the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), must play a leading role in this process.

Epidemiology and antibiotic resistance of bacterial meningitis in Dapaong, northern Togo

Institute of Scientific and Technical Information of China (English)

Simplice D Karou; Abago Balaka; Mitiname Bamok; Damhan Tchelougou; Malki Assih; Kokou Anani; Kodjo Agbonoko; Jacques Simpore; Comlan de Souza

2012-01-01

Objective:To assess the seasonality of the bacterial meningitis and the antibiotic resistance of incriminated bacteria over the last three years in the northern Togo. Methods: From January 2007 to January 2010, 533 cerebrospinal fluids (CSF) samples were collected from patients suspected of meningitis in the Regional Hospital of Dapaong (northern Togo). After microscopic examination, samples were cultured for bacterial identification and antibiotic susceptibility. Results:The study included 533 patients (306 male and 227 female) aged from 1 day to 55 years [average age (13.00±2.07) years]. Bacterial isolation and identification were attempted for 254/533 (47.65%) samples. The bacterial species identified were:Neisseria meningitidis A (N. meningitidis A) (58.27%), Neisseria meningitidis W135 (N. meningitidis W135) (7.09%), Streptococcus pneumoniae (S. pneumoniae) (26.77%), Haemophilus influenza B (H. influenza B) (6.30%) and Enterobacteriaceae (1.57%). The results indicated that bacterial meningitis occur from November to May with a peak in February for H. influenzae and S. pneumoniae and March for Neisseriaceae. The distribution of positive CSF with regards to the age showed that subjects between 6 and 12 years followed by subjects of 0 to 5 years were most affected with respective frequencies of 67.82% and 56.52% (P20%for both bacterial strains), macrolides (resistance rate> 30%for H. influenzae) quinolones (resistance rate>15%for H. influenzae and N. meningitidis W135). Over three years, the prevalence of S. pneumoniae significantly increased from 8.48%to 73.33%(P<0.001), while the changes in the prevalence of H. influenzae B were not statistically significant: 4.24%, vs. 8.89%, (P= 0.233). Conclusions:Our results indicate that data in African countries differ depending on geographical location in relation to the African meningitis belt. This underlines the importance of epidemiological surveillance of bacterial meningitis.

The role of biofilms as environmental reservoirs of antibiotic resistance

Directory of Open Access Journals (Sweden)

Jose Luis eBalcazar

2015-10-01

Full Text Available Antibiotic resistance has become a significant and growing threat to public and environmental health. To face this problem both at local and global scales, a better understanding of the sources and mechanisms that contribute to the emergence and spread of antibiotic resistance is required. Recent studies demonstrate that aquatic ecosystems are reservoirs of resistant bacteria and antibiotic resistance genes as well as potential conduits for their transmission to human pathogens. Despite the wealth of information about antibiotic pollution and its effect on the aquatic microbial resistome, the contribution of environmental biofilms to the acquisition and spread of antibiotic resistance has not been fully explored in aquatic systems. Biofilms are structured multicellular communities embedded in a self-produced extracellular matrix that acts as a barrier to antibiotic diffusion. High population densities and proximity of cells in biofilms also increases the chances for genetic exchange among bacterial species converting biofilms in hot spots of antibiotic resistance. This review focuses on the potential effect of antibiotic pollution on biofilm microbial communities, with special emphasis on ecological and evolutionary processes underlying acquired resistance to these compounds.

Antibiotic resistance pattern and empirical therapy for urinary tract infections in children

International Nuclear Information System (INIS)

Al-Harthi, Abdulla A.; Al-Fifi, Suliman H.

2008-01-01

Objective was to study the type of bacterial pathogen causing urinary tract infection in children at Aseer Central Hospital, southwestern Saudi Arabia and their antimicrobial resistance patterns. A retrospective study of all the urine cultures carried out on the children in the period from January 2003 to December 2006, for a total of 4 years were reviewed at the bacteriology laboratory, Aseer Central Hospital, southwestern region of Saudi Arabia. Their antimicrobial resistances as well as sensitivities were also analyzed. A total of 464 urine cultures were identified. Escherichia coli constitutes the most common pathogen isolated 37.3%, followed by Klebsiella 16.4% and Pseudomonas species 15.7%. In general, there was a significant increase in the resistance rates of different bacterial pathogens to different antibiotics. In spite of an increase in the resistance rates of bacterial pathogens causing UTI, ceftriaxone, imipenem and to some extent Azactam are appropriate for initial empirical intravenous therapy in UTI. In patients with uncomplicated UTI not requiring hospitalization, Nalidixic acid and Nitrofurantoin can be used as oral treatment. (author)

Effectiveness of a Glycylcycline Antibiotic for Reducing the Pathogenicity of Superantigen-Producing Methicillin-Resistant Staphylococcus aureus in Burn Wounds.

Science.gov (United States)

Nosanov, Lauren B; Jo, Daniel Y; Randad, Pranay R; Moffatt, Lauren T; Carney, Bonnie C; Ortiz, Rachel T; Shupp, Jeffrey W

2017-01-01

Objective : Burn-injured patients are highly susceptible to infectious complications, which are often associated with increased morbidity and mortality. Rates of antibiotic resistance have increased, and resistant species such as methicillin-resistant Staphylococcus aureus provide additional challenges in the form of virulence factors. Proteins can disrupt local healing, leading to systemic immune disruption. To optimize outcomes, treatments that reduce pathogenicity must be identified. This study aims to compare a glycylcycline antibiotic-tigecycline-with clindamycin for effectiveness in treating superantigenic methicillin-resistant Staphylococcus aureus in burn wounds. Methods : Sprague-Dawley rats received paired 2 × 2-cm burn wounds, which were subsequently inoculated with known virulence factor-producing methicillin-resistant Staphylococcus aureus or media alone on postinjury day 1. Infected animals received twice-daily tigecycline (high or low dose), twice-daily clindamycin (high or low dose), or saline alone (positive controls). Daily sampling and imaging assessments were performed. Results : Bacterial counts and toxin levels were reduced significantly in antibiotic-treated groups relative to positive controls ( P study supports the use of tigecycline in the treatment of methicillin-resistant Staphylococcus aureus -infected burn wounds. While both protein synthesis inhibitors are effective, tigecycline appears to be superior in controlling toxin levels, enabling better wound healing.

Antimicrobial sensitivity and frequency of DRUG resistance among bacterial strains isolated from cancer patients

International Nuclear Information System (INIS)

Faiz, M.; Bashir, T.

2004-01-01

Blood stream infections (bacteremia) is potentially life threatening. Concomitant with a change in the incidence and epidemiology of infecting organisms, there has been an increase in resistance to many antibiotic compounds. The widespread emergence of resistance among bacterial pathogens has an impact on our ability to treat patients effectively. The changing spectrum of microbial pathogens and widespread emergence of microbial resistance to antibiotic drugs has emphasized the need to monitor the prevalence of resistance in these strains. In the present study frequency of isolation of clinically significant bacteria and their susceptibility and resistance pattern against a wide range of antimicrobial drugs from positive blood cultures collected during 2001-2003 was studied. A total of 102 consecutive isolates were found with 63% gram positive and 44% gram negative strains. The dominating pathogens were Staphylococcus aureus (51%), Streptococci (31%), Pseudomonas (40%), Proteus (13%), Klebsiella (13%). The isolated strains were tested against a wide range of antibiotics belonging to cephalosporins, aminoglycosides and quinolone derivative group by disk diffusion method. It has been observed that isolated strains among gram positive and negative strains showed different level of resistance against aminoglycosides and cephalosporin group of antibiotics with gram positives showing highest number and frequency of resistance against aminoglycosides (40-50%) and cephalosporins.(35-45%) whereas cephalosporins were found to be more effective against gram negatives with low frequency of resistant strains. Cabapenem and quinolone derivative drugs were found to be most effective among other groups in both gram positive and negative strains with 23-41% strains found sensitive to these two drugs. The frequency of sensitive strains against aminoglycoside and cephalosporin in gram negative and gram positive strains were found to be decreasing yearwise with a trend towards an

Fitness tradeoffs of antibiotic resistance in extra-intestinal pathogenic Escherichia coli.

Science.gov (United States)

Basra, Prabh; Alsaadi, Ahlam; Bernal-Astrain, Gabriel; O'Sullivan, Michael Liam; Hazlett, Bryn; Clarke, Leah Marie; Schoenrock, Andrew; Pitre, Sylvain; Wong, Alex

2018-02-07

Evolutionary trade-offs occur when selection on one trait has detrimental effects on other traits. In pathogenic microbes, it has been hypothesized that antibiotic resistance trades off with fitness in the absence of antibiotic. While studies of single resistance mutations support this hypothesis, it is unclear whether trade-offs are maintained over time, due to compensatory evolution and broader effects of genetic background. Here, we leverage natural variation in 39 extra-intestinal clinical isolates of Escherichia coli to assess trade-offs between growth rates and resistance to fluoroquinolone and cephalosporin antibiotics. Whole genome sequencing identifies a broad range of clinically relevant resistance determinants in these strains. We find evidence for a negative correlation between growth rate and antibiotic resistance, consistent with a persistent trade-off between resistance and growth. However, this relationship is sometimes weak, and depends on the environment in which growth rates are measured. Using in vitro selection experiments, we find that compensatory evolution in one environment does not guarantee compensation in other environments. Thus, even in the face of compensatory evolution and other genetic background effects, resistance may be broadly costly, supporting the use of drug restriction protocols to limit the spread of resistance. Furthermore, our study demonstrates the power of using natural variation to study evolutionary trade-offs in microbes. © The Author(s) 2018. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Frequency of isolation and antibiotic resistance patterns of bacterial isolates from wound infections

Directory of Open Access Journals (Sweden)

Stojanović-Radić, Z.

2016-12-01

Full Text Available Six hundred and thirteen bacterial strains were isolated from wound swabs and the isolates were identified on the basis of growth on differential and selective media. In order to test the sensitivity of isolated strains to different antibiotics, the disc diffusion method, according to EUCAST protocol v 5.0 was used. The most common species isolated from wound swabs was Staphylococcus epidermidis (18.4%, followed by Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis (16.8%, 12.7% and 10.4%, respectively. The maximum resistance of Gram-positive cocci was observed to penicillin and the lowest to linezolid. Gram-negative bacteria showed the highest resistance to tetracyclines, while the same strains demonstrated the highest sensitivity to polypeptide antibiotics. Comparison of the resistance patterns of Gramnegative and Gram-positive bacterial strains showed significant difference in the tetracycline efficiency.

Inhibition of bacterial growth by iron oxide nanoparticles with and without attached drug: Have we conquered the antibiotic resistance problem?

Science.gov (United States)

Armijo, Leisha M.; Jain, Priyanka; Malagodi, Angelina; Fornelli, F. Zuly; Hayat, Allison; Rivera, Antonio C.; French, Michael; Smyth, Hugh D. C.; Osiński, Marek

2015-03-01

Pseudomonas aeruginosa is among the top three leading causative opportunistic human pathogens, possessing one of the largest bacterial genomes and an exceptionally large proportion of regulatory genes therein. It has been known for more than a decade that the size and complexity of the P. aeruginosa genome is responsible for the adaptability and resilience of the bacteria to include its ability to resist many disinfectants and antibiotics. We have investigated the susceptibility of P. aeruginosa bacterial biofilms to iron oxide (magnetite) nanoparticles (NPs) with and without attached drug (tobramycin). We also characterized the susceptibility of zero-valent iron NPs, which are known to inactivate microbes. The particles, having an average diameter of 16 nm were capped with natural alginate, thus doubling the hydrodynamic size. Nanoparticle-drug conjugates were produced via cross-linking drug and alginate functional groups. Drug conjugates were investigated in the interest of determining dosage, during these dosage-curve experiments, NPs unbound to drug were tested in cultures as a negative control. Surprisingly, we found that the iron oxide NPs inhibited bacterial growth, and thus, biofilm formation without the addition of antibiotic drug. The inhibitory dosages of iron oxide NPs were investigated and the minimum inhibitory concentrations are presented. These findings suggest that NP-drug conjugates may overcome the antibiotic drug resistance common in P. aeruginosa infections.

Strategies to prevent the occurrence of resistance against antibiotics by using advanced materials.

Science.gov (United States)

Bassegoda, Arnau; Ivanova, Kristina; Ramon, Eva; Tzanov, Tzanko

2018-03-01

Drug resistance occurrence is a global healthcare concern responsible for the increased morbidity and mortality in hospitals, time of hospitalisation and huge financial loss. The failure of the most antibiotics to kill "superbugs" poses the urgent need to develop innovative strategies aimed at not only controlling bacterial infection but also the spread of resistance. The prevention of pathogen host invasion by inhibiting bacterial virulence and biofilm formation, and the utilisation of bactericidal agents with different mode of action than classic antibiotics are the two most promising new alternative strategies to overcome antibiotic resistance. Based on these novel approaches, researchers are developing different advanced materials (nanoparticles, hydrogels and surface coatings) with novel antimicrobial properties. In this review, we summarise the recent advances in terms of engineered materials to prevent bacteria-resistant infections according to the antimicrobial strategies underlying their design.

Antibiotic Susceptibility Patterns of Bacterial Isolates from Pus Samples in a Tertiary Care Hospital of Punjab, India

Directory of Open Access Journals (Sweden)

Rugira Trojan

2016-01-01

Full Text Available We determined the prevalence and antibiotic susceptibilities patterns of bacterial isolates from pus samples collected from patients in a tertiary care hospital of Punjab, India. E. coli was the most prevalent pathogen (51.2% followed by Staphylococcus aureus (21%, Klebsiella pneumoniae (11.6%, Pseudomonas aeruginosa (5.8%, Citrobacter spp. (3.5%, Acinetobacter baumannii (2.3%, Proteus mirabilis (2.3%, and Streptococcus spp. (2.3%. E. coli, K. pneumoniae, A. baumannii, and Citrobacter isolates were resistant to multiple antibiotics including higher generation cephalosporins. S. aureus and Streptococcus isolates were sensitive to cloxacillin and vancomycin. However, P. aeruginosa, P. mirabilis, and Streptococcus isolates were found to be less resistant to the spectrum of antibiotics tested. Overall, our findings indicate the prevalence of resistance to different classes of antibiotics in bacterial isolates from pus infections and hence highlight the need for effective surveillance, regulator reporting, and antibiogram-guided antibiotic prescription.

Interventions on Metabolism: Making Antibiotic-Susceptible Bacteria

Directory of Open Access Journals (Sweden)

Fernando Baquero

2017-11-01

Full Text Available Antibiotics act on bacterial metabolism, and antibiotic resistance involves changes in this metabolism. Interventions on metabolism with drugs might therefore modify drug susceptibility and drug resistance. In their recent article, Martin Vestergaard et al. (mBio 8:e01114-17, 2017, https://doi.org/10.1128/mBio.01114-17 illustrate the possibility of converting intrinsically resistant bacteria into susceptible ones. They reported that inhibition of a central metabolic enzyme, ATP synthase, allows otherwise ineffective polymyxin antibiotics to act on Staphylococcus aureus. The study of the intrinsic resistome of bacterial pathogens has shown that several metabolic genes, including multigene transcriptional regulators, contribute to antibiotic resistance. In some cases, these genes only marginally increase antibiotic resistance, but reduced levels of susceptibility might be critical in the evolution or resistance under low antibiotic concentrations or in the clinical response of highly resistant bacteria. Drug interventions on bacterial metabolism might constitute a critical adjuvant therapy in combination with antibiotics to ensure susceptibility of pathogens with intrinsic or acquired antimicrobial resistance.

Bacterial Enzymes and Antibiotic Resistance- Oral Presentation

Energy Technology Data Exchange (ETDEWEB)

Maltz, Lauren [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2015-08-25

By using protein crystallography and X-ray diffraction, structures of bacterial enzymes were solved to gain a better understanding of how enzymatic modification acts as an antibacterial resistance mechanism. Aminoglycoside phosphotransferases (APHs) are one of three aminoglycoside modifying enzymes that confer resistance to the aminoglycoside antibiotics via enzymatic modification, rendering many drugs obsolete. Specifically, the APH(2”) family vary in their substrate specificities and also in their preference for the phosphate donor (ADP versus GDP). By solving the structures of members of the APH(2”) family of enzymes, we can see how domain movements are important to their substrate specificity. Our structure of the ternary complex of APH(2”)-IIIa with GDP and kanamycin, when compared to the known structures of APH(2”)-IVa, reveals that there are real physical differences between these two enzymes, a structural finding that explains why the two enzymes differ in their preferences for certain aminoglycosides. Another important group of bacterial resistance enzymes are the Class D β-lactamases. Oxacillinase carbapenemases (OXAs) are part of this enzyme class and have begun to confer resistance to ‘last resort’ drugs, most notably carbapenems. Our structure of OXA-143 shows that the conformational flexibility of a conserved hydrophobic residue in the active site (Val130) serves to control the entry of a transient water molecule responsible for a key step in the enzyme’s mechanism. Our results provide insight into the structural mechanisms of these two different enzymes.

Antibiotic resistance determinants in a Pseudomonas putida strain isolated from a hospital.

Directory of Open Access Journals (Sweden)

Lázaro Molina

Full Text Available Environmental microbes harbor an enormous pool of antibiotic and biocide resistance genes that can impact the resistance profiles of animal and human pathogens via horizontal gene transfer. Pseudomonas putida strains are ubiquitous in soil and water but have been seldom isolated from humans. We have established a collection of P. putida strains isolated from in-patients in different hospitals in France. One of the isolated strains (HB3267 kills insects and is resistant to the majority of the antibiotics used in laboratories and hospitals, including aminoglycosides, ß-lactams, cationic peptides, chromoprotein enediyne antibiotics, dihydrofolate reductase inhibitors, fluoroquinolones and quinolones, glycopeptide antibiotics, macrolides, polyketides and sulfonamides. Similar to other P. putida clinical isolates the strain was sensitive to amikacin. To shed light on the broad pattern of antibiotic resistance, which is rarely found in clinical isolates of this species, the genome of this strain was sequenced and analysed. The study revealed that the determinants of multiple resistance are both chromosomally-borne as well as located on the pPC9 plasmid. Further analysis indicated that pPC9 has recruited antibiotic and biocide resistance genes from environmental microorganisms as well as from opportunistic and true human pathogens. The pPC9 plasmid is not self-transmissible, but can be mobilized by other bacterial plasmids making it capable of spreading antibiotic resistant determinants to new hosts.

An investigation of total bacterial communities, culturable antibiotic-resistant bacterial communities and integrons in the river water environments of Taipei city.

Science.gov (United States)

Yang, Chu-Wen; Chang, Yi-Tang; Chao, Wei-Liang; Shiung, Iau-Iun; Lin, Han-Sheng; Chen, Hsuan; Ho, Szu-Han; Lu, Min-Jheng; Lee, Pin-Hsuan; Fan, Shao-Ning

2014-07-30

The intensive use of antibiotics may accelerate the development of antibiotic-resistant bacteria (ARB). The global geographical distribution of environmental ARB has been indicated by many studies. However, the ARB in the water environments of Taiwan has not been extensively investigated. The objective of this study was to investigate the communities of ARB in Huanghsi Stream, which presents a natural acidic (pH 4) water environment. Waishuanghsi Stream provides a neutral (pH 7) water environment and was thus also monitored to allow comparison. The plate counts of culturable bacteria in eight antibiotics indicate that the numbers of culturable carbenicillin- and vancomycin-resistant bacteria in both Huanghsi and Waishuanghsi Streams are greater than the numbers of culturable bacteria resistant to the other antibiotics tested. Using a 16S rDNA sequencing approach, both the antibiotic-resistant bacterial communities (culture-based) and the total bacterial communities (metagenome-based) in Waishuanghsi Stream exhibit a higher diversity than those in Huanghsi Stream were observed. Of the three classes of integron, only class I integrons were identified in Waishuanghsi Stream. Our results suggest that an acidic (pH 4) water environment may not only affect the community composition of antibiotic-resistant bacteria but also the horizontal gene transfer mediated by integrons. Copyright © 2013 Elsevier B.V. All rights reserved.

Selection of antibiotic resistance at very low antibiotic concentrations

OpenAIRE

Sandegren, Linus

2014-01-01

Human use of antibiotics has driven the selective enrichment of pathogenic bacteria resistant to clinically used drugs. Traditionally, the selection of resistance has been considered to occur mainly at high, therapeutic levels of antibiotics, but we are now beginning to understand better the importance of selection of resistance at low levels of antibiotics. The concentration of an antibiotic varies in different body compartments during treatment, and low concentrations of antibiotics are fou...

Genomic and metagenomic technologies to explore the antibiotic resistance mobilome.

Science.gov (United States)

Martínez, José L; Coque, Teresa M; Lanza, Val F; de la Cruz, Fernando; Baquero, Fernando

2017-01-01

Antibiotic resistance is a relevant problem for human health that requires global approaches to establish a deep understanding of the processes of acquisition, stabilization, and spread of resistance among human bacterial pathogens. Since natural (nonclinical) ecosystems are reservoirs of resistance genes, a health-integrated study of the epidemiology of antibiotic resistance requires the exploration of such ecosystems with the aim of determining the role they may play in the selection, evolution, and spread of antibiotic resistance genes, involving the so-called resistance mobilome. High-throughput sequencing techniques allow an unprecedented opportunity to describe the genetic composition of a given microbiome without the need to subculture the organisms present inside. However, bioinformatic methods for analyzing this bulk of data, mainly with respect to binning each resistance gene with the organism hosting it, are still in their infancy. Here, we discuss how current genomic methodologies can serve to analyze the resistance mobilome and its linkage with different bacterial genomes and metagenomes. In addition, we describe the drawbacks of current methodologies for analyzing the resistance mobilome, mainly in cases of complex microbiotas, and discuss the possibility of implementing novel tools to improve our current metagenomic toolbox. © 2016 New York Academy of Sciences.

Microbial ecology, bacterial pathogens, and antibiotic resistant genes in swine manure wastewater as influenced by three swine management systems.

Science.gov (United States)

Brooks, John P; Adeli, Ardeshir; McLaughlin, Michael R

2014-06-15

The environmental influence of farm management in concentrated animal feeding operations (CAFO) can yield vast changes to the microbial biota and ecological structure of both the pig and waste manure lagoon wastewater. While some of these changes may not be negative, it is possible that CAFOs can enrich antibiotic resistant bacteria or pathogens based on farm type, thereby influencing the impact imparted by the land application of its respective wastewater. The purpose of this study was to measure the microbial constituents of swine-sow, -nursery, and -finisher farm manure lagoon wastewater and determine the changes induced by farm management. A total of 37 farms were visited in the Mid-South USA and analyzed for the genes 16S rRNA, spaQ (Salmonella spp.), Camp-16S (Campylobacter spp.), tetA, tetB, ermF, ermA, mecA, and intI using quantitative PCR. Additionally, 16S rRNA sequence libraries were created. Overall, it appeared that finisher farms were significantly different from nursery and sow farms in nearly all genes measured and in 16S rRNA clone libraries. Nearly all antibiotic resistance genes were detected in all farms. Interestingly, the mecA resistance gene (e.g. methicillin resistant Staphylococcus aureus) was below detection limits on most farms, and decreased as the pigs aged. Finisher farms generally had fewer antibiotic resistance genes, which corroborated previous phenotypic data; additionally, finisher farms produced a less diverse 16S rRNA sequence library. Comparisons of Camp-16S and spaQ GU (genomic unit) values to previous culture data demonstrated ratios from 10 to 10,000:1 depending on farm type, indicating viable but not cultivatable bacteria were dominant. The current study indicated that swine farm management schemes positively and negatively affect microbial and antibiotic resistant populations in CAFO wastewater which has future "downstream" implications from both an environmental and public health perspective. Published by Elsevier Ltd.

Tracking acquired antibiotic resistance in commensal bacteria of Galápagos land iguanas: no man, no resistance.

Directory of Open Access Journals (Sweden)

Maria Cristina Thaller

Full Text Available BACKGROUND: Antibiotic resistance, evolving and spreading among bacterial pathogens, poses a serious threat to human health. Antibiotic use for clinical, veterinary and agricultural practices provides the major selective pressure for emergence and persistence of acquired resistance determinants. However, resistance has also been found in the absence of antibiotic exposure, such as in bacteria from wildlife, raising a question about the mechanisms of emergence and persistence of resistant strains under similar conditions, and the implications for resistance control strategies. Since previous studies yielded some contrasting results, possibly due to differences in the ecological landscapes of the studied wildlife, we further investigated this issue in wildlife from a remote setting of the Galapagos archipelago. METHODOLOGY/PRINCIPAL FINDINGS: Screening for acquired antibiotic resistance was carried out in commensal enterobacteria from Conolophus pallidus, the terrestrial iguana of Isla Santa Fe, where: i the abiotic conditions ensure to microbes good survival possibilities in the environment; ii the animal density and their habits favour microbial circulation between individuals; and iii there is no history of antibiotic exposure and the impact of humans and introduced animal species is minimal except for restricted areas. Results revealed that acquired antibiotic resistance traits were exceedingly rare among bacteria, occurring only as non-dominant strains from an area of minor human impact. CONCLUSIONS/SIGNIFICANCE: Where both the exposure to antibiotics and the anthropic pressure are minimal, acquired antibiotic resistance traits are not normally found in bacteria from wildlife, even if the ecological landscape is highly favourable to bacterial circulation among animals. Monitoring antibiotic resistance in wildlife from remote areas could also be a useful tool to evaluate the impact of anthropic pressure.

Tracking acquired antibiotic resistance in commensal bacteria of Galápagos land iguanas: no man, no resistance.

Science.gov (United States)

Thaller, Maria Cristina; Migliore, Luciana; Marquez, Cruz; Tapia, Washington; Cedeño, Virna; Rossolini, Gian Maria; Gentile, Gabriele

2010-02-01

Antibiotic resistance, evolving and spreading among bacterial pathogens, poses a serious threat to human health. Antibiotic use for clinical, veterinary and agricultural practices provides the major selective pressure for emergence and persistence of acquired resistance determinants. However, resistance has also been found in the absence of antibiotic exposure, such as in bacteria from wildlife, raising a question about the mechanisms of emergence and persistence of resistant strains under similar conditions, and the implications for resistance control strategies. Since previous studies yielded some contrasting results, possibly due to differences in the ecological landscapes of the studied wildlife, we further investigated this issue in wildlife from a remote setting of the Galapagos archipelago. Screening for acquired antibiotic resistance was carried out in commensal enterobacteria from Conolophus pallidus, the terrestrial iguana of Isla Santa Fe, where: i) the abiotic conditions ensure to microbes good survival possibilities in the environment; ii) the animal density and their habits favour microbial circulation between individuals; and iii) there is no history of antibiotic exposure and the impact of humans and introduced animal species is minimal except for restricted areas. Results revealed that acquired antibiotic resistance traits were exceedingly rare among bacteria, occurring only as non-dominant strains from an area of minor human impact. Where both the exposure to antibiotics and the anthropic pressure are minimal, acquired antibiotic resistance traits are not normally found in bacteria from wildlife, even if the ecological landscape is highly favourable to bacterial circulation among animals. Monitoring antibiotic resistance in wildlife from remote areas could also be a useful tool to evaluate the impact of anthropic pressure.

Bacterial Species and Antibiotic Sensitivity in Korean Patients Diagnosed with Acute Otitis Media and Otitis Media with Effusion.

Science.gov (United States)

Kim, Sang Hoon; Jeon, Eun Ju; Hong, Seok Min; Bae, Chang Hoon; Lee, Ho Yun; Park, Moo Kyun; Byun, Jae Yong; Kim, Myung Gu; Yeo, Seung Geun

2017-04-01

Changes over time in pathogens and their antibiotic sensitivity resulting from the recent overuse and misuse of antibiotics in otitis media (OM) have complicated treatment. This study evaluated changes over 5 years in principal pathogens and their antibiotic sensitivity in patients in Korea diagnosed with acute OM (AOM) and OM with effusion (OME). The study population consisted of 683 patients who visited the outpatient department of otorhinolaryngology in 7 tertiary hospitals in Korea between January 2010 and May 2015 and were diagnosed with acute AOM or OME. Aural discharge or middle ear fluid were collected from patients in the operating room or outpatient department and subjected to tests of bacterial identification and antibiotic sensitivity. The overall bacteria detection rate of AOM was 62.3% and OME was 40.9%. The most frequently isolated Gram-positive bacterial species was coagulase negative Staphylococcus aureus (CNS) followed by methicillin-susceptible S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), and Streptococcus pneumonia (SP), whereas the most frequently isolated Gram-negative bacterium was Pseudomonas aeruginosa (PA). Regardless of OM subtype, ≥ 80% of CNS and MRSA strains were resistant to penicillin (PC) and tetracycline (TC); isolated MRSA strains showed low sensitivity to other antibiotics, with 100% resistant to PC, TC, cefoxitin (CFT), and erythromycin (EM); and isolated PA showed low sensitivity to quinolone antibiotics, including ciprofloxacin (CIP) and levofloxacin (LFX), and to aminoglycosides. Bacterial species and antibiotic sensitivity did not change significantly over 5 years. The rate of detection of MRSA was higher in OME than in previous studies. As bacterial predominance and antibiotic sensitivity could change over time, continuous and periodic surveillance is necessary in guiding appropriate antibacterial therapy. © 2017 The Korean Academy of Medical Sciences.

Biofilm-mediated Antibiotic-resistant Oral Bacterial Infections: Mechanism and Combat Strategies.

Science.gov (United States)

Kanwar, Indulata; Sah, Abhishek K; Suresh, Preeti K

2017-01-01

Oral diseases like dental caries and periodontal disease are directly associated with the capability of bacteria to form biofilm. Periodontal diseases have been associated to anaerobic Gram-negative bacteria forming a subgingival plaque (Porphyromonas gingivalis, Actinobacillus, Prevotella and Fusobacterium). Biofilm is a complex bacterial community that is highly resistant to antibiotics and human immunity. Biofilm communities are the causative agents of biological developments such as dental caries, periodontitis, peri-implantitis and causing periodontal tissue breakdown. The review recapitulates the latest advancements in treatment of clinical biofilm infections and scientific investigations, while these novel anti-biofilm strategies are still in nascent phases of development, efforts dedicated to these technologies could ultimately lead to anti-biofilm therapies that are superior to the current antibiotic treatment. This paper provides a review of the literature focusing on the studies on biofilm in the oral cavity, formation of dental plaque biofilm, drug resistance of bacterial biofilm and the antibiofilm approaches as biofilm preventive agents in dentistry, and their mechanism of biofilm inhibition. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Pattern of antibiotic resistant mastitis in dairy cows

Directory of Open Access Journals (Sweden)

D. Chandrasekaran

2014-06-01

Full Text Available Aim: To study the prevalence of drug resistant mastitis and their pattern of antibiotic resistance in dairy cows from Tamil Nadu. Materials and Methods: Isolation and identification of resistant pathogens were performed from acute clinical mastitis samples. Based on culture, isolation and sensitivity tests, cows with resistant mastitis were grouped as; Group I: Escherichia coli (n=119, Group II: Staphylococcus aureus (n=104 and Group III: Methicillin-resistant Staphylococcal aureus (MRSA (n=12. The isolates were tested using agar disc diffusion method for their antimicrobial susceptibility and modified resazurin assay microdilution technique for minimum inhibitory concentration (MIC to 8 antimicrobial drugs. The organisms were also confirmed for their identity by performing PCR on the bacterial pellet targeting the specific genes such as 16s-23s rRNA, mecA and blaZ respectively for the resistant pathogens and also confirmed by sequencing. Results: Antibiotic resistant mastitis was detected in 235 out of 401 cows accounting to 56.1%. The predominant resistant causative pathogen was E. coli (50.64% followed by S. aureus (44.25% and MRSA (5.11%. In vitro antibiotic sensitivity test and MIC breakpoints, E. coli, S. aureus and MRSA organisms showed more sensitivity to enrofloxacin, amoxicillin + sulbactam, gentamicin and ceftriaxone and had highest resistant to penicillin followed by amoxicillin, oxytetracycline and methicillin. E. coli and S. aureus isolates were found to be resistant to 1 or 2 antimicrobials, whereas most of the MRSA isolates were found to be multi-drug resistant i.e resistance to 3 or more of antimicrobials. Out of 235 milk samples, the specific target gene 16s-23s rRNA (E. coli , 16s-23s rRNA (S. aureus and MRSA (mecA and blaZ could be amplified from 119, 104 and 12 isolates with a percentage positivity of 50.64 (119/235, 89.64 (104/116 and 10.34 (12/116 respectively. Conclusion: Prevalence of antimicrobial resistance (AMR in

A mathematical model for expected time to extinction of pathogenic bacteria through antibiotic

Science.gov (United States)

Ghosh, M. K.; Nandi, S.; Roy, P. K.

2016-04-01

Application of antibiotics in human system to prevent bacterial diseases like Gastritis, Ulcers, Meningitis, Pneumonia and Gonorrhea are indispensable. Antibiotics saved innumerable lives and continue to be a strong support for therapeutic application against pathogenic bacteria. In human system, bacterial diseases occur when pathogenic bacteria gets into the body and begin to reproduce and crowd out healthy bacteria. In this process, immature bacteria releases enzyme which is essential for bacterial cell-wall biosynthesis. After complete formation of cell wall, immature bacteria are converted to mature or virulent bacteria which are harmful to us during bacterial infections. Use of antibiotics as drug inhibits the bacterial cell wall formation. After application of antibiotics within body, the released bacterial enzyme binds with antibiotic molecule instead of its functional site during the cell wall synthesis in a competitive inhibition approach. As a consequence, the bacterial cell-wall formation as well as maturation process of pathogenic bacteria is halted and the disease is cured with lysis of bacterial cells. With this idea, a mathematical model has been developed in the present research investigation to review the inhibition of biosynthesis of bacterial cell wall by the application of antibiotics as drug in the light of enzyme kinetics. This approach helps to estimate the expected time to extinction of the pathogenic bacteria. Our mathematical approach based on the enzyme kinetic model for finding out expected time to extinction contributes favorable results for understanding of disease dynamics. Analytical and numerical results based on simulated findings validate our mathematical model.

Bacterial viruses enable their host to acquire antibiotic resistance genes from neighbouring cells

DEFF Research Database (Denmark)

Haaber, Jakob Krause; Leisner, Jørgen; Cohn, Marianne Thorup

2016-01-01

Prophages are quiescent viruses located in the chromosomes of bacteria. In the human pathogen, Staphylococcus aureus, prophages are omnipresent and are believed to be responsible for the spread of some antibiotic resistance genes. Here we demonstrate that release of phages from a subpopulation of S....... aureus cells enables the intact, prophage-containing population to acquire beneficial genes from competing, phage-susceptible strains present in the same environment. Phage infection kills competitor cells and bits of their DNA are occasionally captured in viral transducing particles. Return...... of such particles to the prophage-containing population can drive the transfer of genes encoding potentially useful traits such as antibiotic resistance. This process, which can be viewed as ‘auto-transduction’, allows S. aureus to efficiently acquire antibiotic resistance both in vitro and in an in vivo virulence...

Causative pathogens and antibiotic resistance in children hospitalized for urinary tract infection.

Science.gov (United States)

Koçak, Mesut; Büyükkaragöz, Bahar; Çelebi Tayfur, Asli; Çaltik, Aysun; Köksoy, Adem Yasin; Çizmeci, Zeynep; Günbey, Sacit

2016-06-01

Urinary tract infections (UTI) are one of the most common bacterial infections in children and a major cause of hospitalization. In this study we investigated the clinical characteristics, causative uropathogens; their antibiotic susceptibility and resistance patterns, treatment modalities and efficacy in children hospitalized for UTI in a tertiary care setting. Patients hospitalized for an upper UTI between March 2009 and July 2014 were enrolled. The urine culture-antibiogram results and accompanying urinary tract abnormalities were recorded retrospectively. A total of 142 patients (104 girls, 73.2%; 38 boys, 26.8%) were enrolled. Mean patient age was 32.6 ± 4.1 months. History of recurrent UTI was present in 45.8% (n = 65), with prior hospitalization in 12.0% (n = 17). Frequency of vesicoureteral reflux was 18.3% (n = 26). Gram-negative enteric microorganisms yielded growth in all culture-positive UTI and the most common microorganism was Escherichia coli (n = 114, 80.3%). Extended spectrum beta-lactamase-producing (ESBL (+)) bacterial strains were detected in 49.3% (n = 70), with third-generation cephalosporin resistance in all and increased duration of hospitalization. The prevalence of UTI with ESBL (+) bacterial strains with multi-drug resistance is increasing in the hospitalized pediatric population, therefore rational use of antibiotics is essential. © 2015 Japan Pediatric Society.

Assessment of anaerobic bacterial diversity and its effects on anaerobic system stability and the occurrence of antibiotic resistance genes.

Science.gov (United States)

Aydin, Sevcan; Ince, Bahar; Ince, Orhan

2016-05-01

This study evaluated the link between anaerobic bacterial diversity and, the biodegradation of antibiotic combinations and assessed how amending antibiotic combination and increasing concentration of antibiotics in a stepwise fashion influences the development of resistance genes in anaerobic reactors. The biodegradation, sorption and occurrence of the known antibiotic resistance genes (ARGs) of erythromycin and tetracycline were investigated using the processes of UV-HPLC and qPCR analysis respectively. Ion Torrent sequencing was used to detect microbial community changes in response to the addition of antibiotics. The overall results indicated that changes in the structure of a microbial community lead to changes in biodegradation capacity, sorption of antibiotics combinations and occurrence of ARGs. The enhanced biodegradation efficiency appeared to generate variations in the structure of the bacterial community. The results suggested that controlling the ultimate Gram-negative bacterial community, especially Acinetobacter-related populations, may promote the successful biodegradation of antibiotic combinations and reduce the occurrence of ARGs. Copyright © 2016 Elsevier Ltd. All rights reserved.

IDENTIFICATION AND ANTIBIOTIC RESISTANCE PROFILE OFENTEROBACTERIACEAE SPECIES AND LACTOBACILLUS SPP. ISOLATED FROM HONEY BEES (APIS MELLIFERA DIGESTIVE TRACT

Directory of Open Access Journals (Sweden)

Lukáš Hleba

2014-02-01

Full Text Available Honey bees play important role in agricultural environment as main pollinators. Its important for many agricultural and wild plants. Also honey bee are producers of honey, which is consumed directly and it should be not a heat treatment. Many bacteria can be survive in honey for long time. Some of these bacteria are human and animal facultative pathogens, including Enterobactericaeae genera. If these bacteria contain antibiotic resistant genes than it can to leads to troubles in healing of some of bacterial infections. Lactobacillus spp. can be a reservoir of resistant genes for pathogenic bacterial strains. In this study we isolated Enterobacteriaceae strains from digestive tracts of honey bees. These strains was tested to the eight selected antibiotics by disc diffusion method and strains were indentified by MALDI TOF MS Biotyper. From this study we determined resistance to piperacillin in the highest level. Equally, we determined that Citrobacter gillenii was resistant to three antibiotics (piperacillin, chloramphenicol and levofloxacin from eight. Resistance to other antibiotics were determined in low levels and other indentified bacteria were resistant to one antibiotic, if any. Also we detected resistance in Lactobacillus spp. and determined MICs distribution for some selected antibiotics. For absence of similar studies we could not to discuss our results and we think that further experiments and studies are needed.

Antibiotic Use in Agriculture and Its Consequential Resistance in Environmental Sources: Potential Public Health Implications

Directory of Open Access Journals (Sweden)

Christy Manyi-Loh

2018-03-01

Full Text Available Due to the increased demand of animal protein in developing countries, intensive farming is instigated, which results in antibiotic residues in animal-derived products, and eventually, antibiotic resistance. Antibiotic resistance is of great public health concern because the antibiotic-resistant bacteria associated with the animals may be pathogenic to humans, easily transmitted to humans via food chains, and widely disseminated in the environment via animal wastes. These may cause complicated, untreatable, and prolonged infections in humans, leading to higher healthcare cost and sometimes death. In the said countries, antibiotic resistance is so complex and difficult, due to irrational use of antibiotics both in the clinical and agriculture settings, low socioeconomic status, poor sanitation and hygienic status, as well as that zoonotic bacterial pathogens are not regularly cultured, and their resistance to commonly used antibiotics are scarcely investigated (poor surveillance systems. The challenges that follow are of local, national, regional, and international dimensions, as there are no geographic boundaries to impede the spread of antibiotic resistance. In addition, the information assembled in this study through a thorough review of published findings, emphasized the presence of antibiotics in animal-derived products and the phenomenon of multidrug resistance in environmental samples. This therefore calls for strengthening of regulations that direct antibiotic manufacture, distribution, dispensing, and prescription, hence fostering antibiotic stewardship. Joint collaboration across the world with international bodies is needed to assist the developing countries to implement good surveillance of antibiotic use and antibiotic resistance.

Antibiotic Use in Agriculture and Its Consequential Resistance in Environmental Sources: Potential Public Health Implications.

Science.gov (United States)

Manyi-Loh, Christy; Mamphweli, Sampson; Meyer, Edson; Okoh, Anthony

2018-03-30

Due to the increased demand of animal protein in developing countries, intensive farming is instigated, which results in antibiotic residues in animal-derived products, and eventually, antibiotic resistance. Antibiotic resistance is of great public health concern because the antibiotic-resistant bacteria associated with the animals may be pathogenic to humans, easily transmitted to humans via food chains, and widely disseminated in the environment via animal wastes. These may cause complicated, untreatable, and prolonged infections in humans, leading to higher healthcare cost and sometimes death. In the said countries, antibiotic resistance is so complex and difficult, due to irrational use of antibiotics both in the clinical and agriculture settings, low socioeconomic status, poor sanitation and hygienic status, as well as that zoonotic bacterial pathogens are not regularly cultured, and their resistance to commonly used antibiotics are scarcely investigated (poor surveillance systems). The challenges that follow are of local, national, regional, and international dimensions, as there are no geographic boundaries to impede the spread of antibiotic resistance. In addition, the information assembled in this study through a thorough review of published findings, emphasized the presence of antibiotics in animal-derived products and the phenomenon of multidrug resistance in environmental samples. This therefore calls for strengthening of regulations that direct antibiotic manufacture, distribution, dispensing, and prescription, hence fostering antibiotic stewardship. Joint collaboration across the world with international bodies is needed to assist the developing countries to implement good surveillance of antibiotic use and antibiotic resistance.

Antibiotic Resistant Bacteria And Their Associated Resistance Genes in a Conventional Municipal Wastewater Treatment Plant

KAUST Repository

Aljassim, Nada I.

2013-12-01

With water scarcity as a pressing issue in Saudi Arabia and other Middle Eastern countries, the treatment and reuse of municipal wastewater is increasingly being used as an alternative water source to supplement country water needs. Standards are in place to ensure a safe treated wastewater quality, however they do not regulate pathogenic bacteria and emerging contaminants. Information is lacking on the levels of risk to public health associated with these factors, the efficiency of conventional treatment strategies in removing them, and on wastewater treatment in Saudi Arabia in general. In this study, a municipal wastewater treatment plant in Saudi Arabia is investigated to assess the efficiency of conventional treatment in meeting regulations and removing pathogens and emerging contaminants. The study found pathogenic bacterial genera, antibiotic resistance genes and antibiotic resistant bacteria, many of which were multi-resistant in plant discharges. It was found that although the treatments are able to meet traditional quality guidelines, there remains a risk from the discussed contaminants with wastewater reuse. A deeper understanding of this risk, and suggestions for more thorough guidelines and monitoring are needed.

Combating multidrug-resistant Gram-negative bacterial infections.

Science.gov (United States)

Xu, Ze-Qi; Flavin, Michael T; Flavin, John

2014-02-01

Multidrug-resistant (MDR) bacterial infections, especially those caused by Gram-negative pathogens, have emerged as one of the world's greatest health threats. The development of novel antibiotics to treat MDR Gram-negative bacteria has, however, stagnated over the last half century. This review provides an overview of recent R&D activities in the search for novel antibiotics against MDR Gram-negatives. It provides emphasis in three key areas. First, the article looks at new analogs of existing antibiotic molecules such as β-lactams, tetracyclines, and aminoglycoside as well as agents against novel bacterial targets such as aminoacyl-tRNA synthetase and peptide deformylase. Second, it also examines alternative strategies to conventional approaches including cationic antimicrobial peptides, siderophores, efflux pump inhibitors, therapeutic antibodies, and renewed interest in abandoned treatments or those with limited indications. Third, the authors aim to provide an update on the current clinical development status for each drug candidate. The traditional analog approach is insufficient to meet the formidable challenge brought forth by MDR superbugs. With the disappointing results of the genomics approach for delivering novel targets and drug candidates, alternative strategies to permeate the bacterial cell membrane, enhance influx, disrupt efflux, and target specific pathogens via therapeutic antibodies are attractive and promising. Coupled with incentivized business models, governmental policies, and a clarified regulatory pathway, it is hoped that the antibiotic pipeline will be filled with an effective armamentarium to safeguard global health.

Invasive Bacterial Pathogens and their Antibiotic Susceptibility ...

African Journals Online (AJOL)

The isolates showed high rates of resistance to most antibiotics tested. The range of resistance for gram positive bacteria were 0% to 85.7%, and for gram negative from 0% to 100%. None of the isolates were resistance to ciprofloxacin and ceftriaxone. CONCLUSION: Our study result showed the presence of invasive ...

Antibiotic resistance: current issues and future strategies

Directory of Open Access Journals (Sweden)

Giancarlo Scarafile

2016-09-01

Full Text Available The antibiotic resistance (antimicrobial resistance – AMR and the particular emergence of multi-resistant bacterial strains, is a problem of clinical relevance involving serious threats to public health worldwide. From early this decade, a lot of studies have demonstrated a significant increase in the rates of antibiotic resistance by bacterial pathogens responsible for nosocomial and community infections all over the world. The AMR leads to a reduced drug efficacy in the treatment options available and therefore, to an increase in mortality rates. The original causes of the phenomenon are: environmental factors which favor a mutation of the genetic bacterial inheritance, thereby inhibiting the active ingredient of the antibiotics; unsuitable administering of antibiotics in veterinary, incorrect taking both in hospitals and at home and, lately, lack of investments in the development of new drugs. The alarming epidemiological data prompted the World Health Organization (WHO in 2011 to coin the slogan "No action today, no cure tomorrow" in order to immediately implement a new strategy to improve the use of available drugs and to accelerate the introduction of new ones through a new phase of research involving private and public institutions. The European Union has stressed that the surveillance is considered an essential factor for an effective response to this problem but it has also highlighted that the results produced have been lower than expectations because of serious shortcomings such as lack of methodological standards, insufficient data sharing and no coordination among European countries. In Italy the situation is much more troubling; in fact, according to the Ministry of Health, 5000-7000 yearly deaths are deemed due to nosocomial infections, with an annual cost of more than 100 million €.These figures explain how the fight against infections is far from being won. The purpose of this review is to analyze the basic causes of the

Enteric bacterial pathogens in children with diarrhea in Niger: diversity and antimicrobial resistance.

Directory of Open Access Journals (Sweden)

Céline Langendorf

Full Text Available Although rotavirus is the leading cause of severe diarrhea among children in sub-Saharan Africa, better knowledge of circulating enteric pathogenic bacteria and their antimicrobial resistance is crucial for prevention and treatment strategies.As a part of rotavirus gastroenteritis surveillance in Maradi, Niger, we performed stool culture on a sub-population of children under 5 with moderate-to-severe diarrhea between April 2010 and March 2012. Campylobacter, Shigella and Salmonella were sought with conventional culture and biochemical methods. Shigella and Salmonella were serotyped by slide agglutination. Enteropathogenic Escherichia coli (EPEC were screened by slide agglutination with EPEC O-typing antisera and confirmed by detection of virulence genes. Antimicrobial susceptibility was determined by disk diffusion. We enrolled 4020 children, including 230 with bloody diarrhea. At least one pathogenic bacterium was found in 28.0% of children with watery diarrhea and 42.2% with bloody diarrhea. Mixed infections were found in 10.3% of children. EPEC, Salmonella and Campylobacter spp. were similarly frequent in children with watery diarrhea (11.1%, 9.2% and 11.4% respectively and Shigella spp. were the most frequent among children with bloody diarrhea (22.1%. The most frequent Shigella serogroup was S. flexneri (69/122, 56.5%. The most frequent Salmonella serotypes were Typhimurimum (71/355, 20.0%, Enteritidis (56/355, 15.8% and Corvallis (46/355, 13.0%. The majority of putative EPEC isolates was confirmed to be EPEC (90/111, 81.1%. More than half of all Enterobacteriaceae were resistant to amoxicillin and co-trimoxazole. Around 13% (46/360 Salmonella exhibited an extended-spectrum beta-lactamase phenotype.This study provides updated information on enteric bacteria diversity and antibiotic resistance in the Sahel region, where such data are scarce. Whether they are or not the causative agent of diarrhea, bacterial infections and their antibiotic

The Antibiotic Resistance Profiles of Bacterial Strains Isolated from Patients with Hospital-Acquired Bloodstream and Urinary Tract Infections

Directory of Open Access Journals (Sweden)

Hamed Ghadiri

2012-01-01

Full Text Available Treatment of nosocomial infections is becoming difficult due to the increasing trend of antibiotics resistance. Current knowledge on antibiotic resistance pattern is essential for appropriate therapy. We aimed to evaluate antibiotic resistance profiles in nosocomial bloodstream and urinary tract pathogens. A total of 129 blood stream and 300 urinary tract positive samples were obtained from patients referring to Besat hospital over a two-year period (2009 and 2010. Antibiotic sensitivity was ascertained using the Kirby-Bauer disk diffusion technique according to CLSI guidelines. Patient's data such as gender and age were recorded. The ratio of gram-negative to gram-positive bacteria in BSIs was 1.6 : 1. The most prevalent BSI pathogen was Coagulase-Negative Staphylococci (CoNS. The highest resistance rate of CoNS was against penicillin (91.1% followed by ampicillin (75.6%, and the lowest rate was against vancomycin (4.4%. Escherichia coli was the most prevalent pathogen isolated from urinary tract infections (UTIs. Ratio of gram-negative to gram-positive bacteria was 3.2 : 1. The highest resistance rate of E. coli isolates was against nalidixic acid (57.7%. The present study showed that CoNS and E. coli are the most common causative agents of nosocomial BSIs and UTIs, and control of infection needs to be addressed in both antibiotic prescription and general hygiene.

Common Bacterial Pathogens and their Antibiotic Sensitivity

African Journals Online (AJOL)

these three drugs can be used in treating most from this study suggest that these three drugs can be used in treating most bacterial infections. This would be particularly useful in health set-ups where culturing and sensitivity testing is impossible, although the availability and cost effectiveness of these antibiotics is in ...

Stepwise impact of urban wastewater treatment on the bacterial community structure, antibiotic contents, and prevalence of antimicrobial resistance.

Science.gov (United States)

Wang, Mingyu; Shen, Weitao; Yan, Lei; Wang, Xin-Hua; Xu, Hai

2017-12-01

Bacteria, antibiotics, and antibiotic resistance determinants are key biological pollutants in aquatic systems, which may lead to bacterial infections or prevent the cure of bacterial infections. In this study, we investigated how the wastewater treatment processes in wastewater treatment plants (WWTPs) affect these pollutants. We found that the addition of oxygen, polyaluminum chloride (PAC), and polyacrylamide (PAM), as well as ultraviolet (UV) disinfection could significantly alter the bacterial communities in the water samples. An overall shift from Gram-negative bacteria to Gram-positive bacteria was observed throughout the wastewater treatment steps, but the overall bacterial biomass was not reduced in the WWTP samples. The antibiotic contents were reduced by the WWTP, but the size of the reduction and the step when antibiotic degradation occurred differed among antibiotics. Ciprofloxacin, sulfamethoxazole and erythromycin could be removed completely by the WWTP, whereas cephalexin could not. The removal of ciprofloxacin, cephalexin, and erythromycin occurred in the anaerobic digester, whereas the removal of sulfamethoxazole occurred after the addition of PAC and PAM, and UV disinfection. Antimicrobial resistance determinants were highly prevalent in all of the samples analyzed, except for those targeting vancomycin and colistin. However, wastewater treatment was ineffective at removing antimicrobial resistance determinants from wastewater. There were strong correlations between intI1, floR, sul1, and ermB, thereby suggesting the importance of integrons for the spread of these antimicrobial resistance genes. In general, this study comprised a stepwise analysis of the impact of WWTPs on three biological pollutants: bacteria, antibiotics, and antimicrobial resistance determinants, where our results suggest that the design of WWTPs needs to be improved to address the threats due to these pollutants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mutations in the Bacterial Ribosomal Protein L3 and Their Association with Antibiotic Resistance

Science.gov (United States)

Klitgaard, Rasmus N.; Ntokou, Eleni; Nørgaard, Katrine; Biltoft, Daniel; Hansen, Lykke H.; Trædholm, Nicolai M.; Kongsted, Jacob

2015-01-01

Different groups of antibiotics bind to the peptidyl transferase center (PTC) in the large subunit of the bacterial ribosome. Resistance to these groups of antibiotics has often been linked with mutations or methylations of the 23S rRNA. In recent years, there has been a rise in the number of studies where mutations have been found in the ribosomal protein L3 in bacterial strains resistant to PTC-targeting antibiotics but there is often no evidence that these mutations actually confer antibiotic resistance. In this study, a plasmid exchange system was used to replace plasmid-carried wild-type genes with mutated L3 genes in a chromosomal L3 deletion strain. In this way, the essential L3 gene is available for the bacteria while allowing replacement of the wild type with mutated L3 genes. This enables investigation of the effect of single mutations in Escherichia coli without a wild-type L3 background. Ten plasmid-carried mutated L3 genes were constructed, and their effect on growth and antibiotic susceptibility was investigated. Additionally, computational modeling of the impact of L3 mutations in E. coli was used to assess changes in 50S structure and antibiotic binding. All mutations are placed in the loops of L3 near the PTC. Growth data show that 9 of the 10 mutations were well accepted in E. coli, although some of them came with a fitness cost. Only one of the mutants exhibited reduced susceptibility to linezolid, while five exhibited reduced susceptibility to tiamulin. PMID:25845869

Coping with antibiotic resistance: combining nanoparticles with antibiotics and other antimicrobial agents.

Science.gov (United States)

Allahverdiyev, Adil M; Kon, Kateryna Volodymyrivna; Abamor, Emrah Sefik; Bagirova, Malahat; Rafailovich, Miriam

2011-11-01

The worldwide escalation of bacterial resistance to conventional medical antibiotics is a serious concern for modern medicine. High prevalence of multidrug-resistant bacteria among bacteria-based infections decreases effectiveness of current treatments and causes thousands of deaths. New improvements in present methods and novel strategies are urgently needed to cope with this problem. Owing to their antibacterial activities, metallic nanoparticles represent an effective solution for overcoming bacterial resistance. However, metallic nanoparticles are toxic, which causes restrictions in their use. Recent studies have shown that combining nanoparticles with antibiotics not only reduces the toxicity of both agents towards human cells by decreasing the requirement for high dosages but also enhances their bactericidal properties. Combining antibiotics with nanoparticles also restores their ability to destroy bacteria that have acquired resistance to them. Furthermore, nanoparticles tagged with antibiotics have been shown to increase the concentration of antibiotics at the site of bacterium-antibiotic interaction, and to facilitate binding of antibiotics to bacteria. Likewise, combining nanoparticles with antimicrobial peptides and essential oils generates genuine synergy against bacterial resistance. In this article, we aim to summarize recent studies on interactions between nanoparticles and antibiotics, as well as other antibacterial agents to formulate new prospects for future studies. Based on the promising data that demonstrated the synergistic effects of antimicrobial agents with nanoparticles, we believe that this combination is a potential candidate for more research into treatments for antibiotic-resistant bacteria.

Celecoxib Enhances the Efficacy of Low-Dose Antibiotic Treatment against Polymicrobial Sepsis in Mice and Clinical Isolates of ESKAPE Pathogens.

Science.gov (United States)

Annamanedi, Madhavi; Varma, Gajapati Y N; Anuradha, K; Kalle, Arunasree M

2017-01-01

Treatment of multidrug resistant bacterial infections has been a great challenge globally. Previous studies including our study have highlighted the use of celecoxib, a non-steroidal anti-inflammatory drug in combination with antibiotic has decreased the minimal inhibitory concentration to limit Staphylococcus aureus infection. However, the efficacy of this combinatorial treatment against various pathogenic bacteria is not determined. Therefore, we have evaluated the potential use of celecoxib in combination with low doses of antibiotic in limiting Gram-positive and Gram-negative bacteria in vivo in murine polymicrobial sepsis developed by cecum ligation and puncture (CLP) method and against clinically isolated human ESKAPE pathogens ( Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa , and Enterobacter species). The in vivo results clearly demonstrated a significant reduction in the bacterial load in different organs and in the inflammatory markers such as COX-2 and NF-κB via activation of SIRT1 in mice treated with imipenem, a choice of antibiotic for polymicrobial sepsis treatment. Combinatorial treatment of ampicillin and celecoxib was effective on clinical isolates of ESKAPE pathogens, 45% of tested clinical isolates showed more than 50% reduction in the colony forming units when compared to ampicillin alone. In conclusion, this non-traditional treatment strategy might be effective in clinic to reduce the dose of antibiotic to treat drug-resistant bacterial infections.

Complete genome sequence analysis of the fish pathogen Flavobacterium columnare provides insights into antibiotic resistance and pathogenicity related genes.

Science.gov (United States)

Zhang, Yulei; Zhao, Lijuan; Chen, Wenjie; Huang, Yunmao; Yang, Ling; Sarathbabu, V; Wu, Zaohe; Li, Jun; Nie, Pin; Lin, Li

2017-10-01

We analyzed here the complete genome sequences of a highly virulent Flavobacterium columnare Pf1 strain isolated in our laboratory. The complete genome consists of a 3,171,081 bp circular DNA with 2784 predicted protein-coding genes. Among these, 286 genes were predicted as antibiotic resistance genes, including 32 RND-type efflux pump related genes which were associated with the export of aminoglycosides, indicating inducible aminoglycosides resistances in F. columnare. On the other hand, 328 genes were predicted as pathogenicity related genes which could be classified as virulence factors, gliding motility proteins, adhesins, and many putative secreted proteases. These genes were probably involved in the colonization, invasion and destruction of fish tissues during the infection of F. columnare. Apparently, our obtained complete genome sequences provide the basis for the explanation of the interactions between the F. columnare and the infected fish. The predicted antibiotic resistance and pathogenicity related genes will shed a new light on the development of more efficient preventional strategies against the infection of F. columnare, which is a major worldwide fish pathogen. Copyright © 2017 Elsevier Ltd. All rights reserved.

Antibiotic resistance and pathogenicity factors in Staphylococcus aureus isolated from mastitic Sahiwal cattle.

Science.gov (United States)

Kumar, Ravinder; Yadav, B R; Singh, R S

2011-03-01

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious problem in dairy animals suffering from mastitis. In the present study, the distribution of mastitic MRSA and antibiotic resistance was studied in 107 strains of S. aureus isolated from milk samples from 195 infected udders. The characterizations pathogenic factors (adhesin and toxin genes) and antibiotic susceptibility of isolates were carried out using gene amplification and disc diffusion assays, respectively. A high prevalence of MRSA was observed in the tested isolates (13.1%). The isolates were also highly resistant to antibiotics, i.e. 36.4% were resistant to streptomycin, 33.6% to oxytetracycline, 29.9% to gentamicin and 26.2% each to chloramphenicol, pristinomycin and ciprofloxacin. A significant variation in the expression of pathogenic factors (Ig, coa and clf) was observed in these isolates. The overall distribution of adhesin genes ebp, fib, bbp, fnbB, cap5, cap8, map and cna in the isolates was found to be 69.1, 67.2, 6.5, 20.5, 60.7, 26.1, 81.3 and 8.4%, respectively. The presence of fib, fnbB, bbp and map genes was considerably greater in MRSA than in methicillin-susceptible S. aureus (MSSA) isolates. The proportions of toxin genes, namely, hlb, seb, sec, sed, seg and sei, in the isolates were found to be 94.3, 0.9, 8.4, 0.9, 10.2 and 49.5%, respectively. The proportions of agr genes I, II, III and IV were found to be 39.2, 27.1, 21.5 and 12.1%, respectively. A few isolates showed similar antibiotic-resistance patterns, which could be due to identical strains or the dissemination of the same strains among animals. These findings can be utilized in mastitis treatment programmes and antimicrobials strategies in organized herd.

Bacteriophages for detection of bacterial pathogens

International Nuclear Information System (INIS)

Kutateladze, M.

2009-01-01

The G. Eliava Institute of Bacteriophages, Microbiology and Virology (Tbilisi, Georgia) is one of the most famous institutions focused on bacteriophage research for the elaboration of appropriate phage methodologies for human and animal protection. The main direction of the institute is the study and production of bacteriophages against intestinal disorders (dysentery, typhoid, intesti) and purulent-septic infections (staphylococcus, streptococcus, pyophage, etc.). These preparations were successfully introduced during the Soviet era, and for decades were used throughout the former Soviet Union and in other Socialist countries for the treatment, prophylaxis, and diagnosis of various infectious diseases, including those caused by antibiotic-resistant bacterial strains. Bacteriophages were widely used for identifying and detecting infections caused by the most dangerous pathogens and causative agents of epidemiological outbreaks. The specific topic of this presentation is the phage typing of bacterial species, which can be an important method for epidemiological diagnostics. Together with different genetic methodologies - such as PCR-based methods, PFGE, plasmid fingerprinting, and ribosomal typing - phage typing is one method for identifying bacterial pathogens. The method has a high percentage of determination of phage types, high specificity of reaction, and is easy for interpretation and use by health workers. Phage typing was applied for inter-species differentiation of different species of Salmonella, S. typhi, Brucella spp, Staphylococcus aureus, E. col,i Clostridium deficile, Vibrio cholerae, Yersinia pestis, Yersinia enterocolitica, Lysteria monocytogenes, Clostridium perfringens, Clostridium tetani, plant pathogens, and other bacterial pathogens. In addition to addressing the utility and efficacy of phage typing, the paper will discuss the isolation and selection of diagnostic typing phages for interspecies differentiation of pathogens that is necessary

Evaluation of antibiotic resistant bacteria in underground drinking water and transfer of their resistant character to normal flora of the body.

Science.gov (United States)

Alam, Mehboob; Khan, Naqab; Rehman, Khurram; Khan, Samiullah; Niazi, Zahid Rasul; Shah, Kifayatullah; Baloch, Natasha; Khan, Barkat Ali

2018-03-01

The untreated surface water for drinking and domestic use is an alarming situation to public health especially in prevalence of antibiotics resistant bacteria. This investigation aimed to isolate and identify the antibiotic resistance bacteria in underground water samples in district Dera Ismail Khan, Pakistan. The underground water samples were collected from four different places using hand pumps (Khyber town, riverside, Gomal University and united town). Cultured on nutrient agar media, identified by Gam staining and biochemical tests. There after antibiotic resistance assay were performed by measuring zone of inhibition of different antibiotics by disc diffusion method. Six different bacterial colonies were isolated and identified as Enterobacteriaceae, Serriata specie, Proteues, Pseudomonas, all these bacterial colonies were 33% resistant to chloramphenicol with and 100% resistant to amoxicillin. Some colonies were also considered as resistant, according to the criteria of National Committee for Clinical Records (NCCL) that less than 10mm zone of inhibition are considered as resistant. Subsequently, the chloramphenicol resistance bacteria were analyzed for their ability to transfer resistant gene to sensitive bacteria. In in-vitro method, an isolate M1b (resistant) was found capable to transfer resistance gene to M1a isolate (sensitive) in nutrient rich environment. It was concluded that antibiotics resistance bacteria found in underground water, moreover capable of transferring the antibiotic resistant character to suitable recipient i.e. normal flora of the body or to other pathogens by conjugation.

RecA: a universal drug target in pathogenic bacteria.

Science.gov (United States)

Pavlopoulou, Athanasia

2018-01-01

The spread of bacterial infectious diseases due to the development of resistance to antibiotic drugs in pathogenic bacteria is an emerging global concern. Therefore, the efficacious management and prevention of bacterial infections are major public health challenges. RecA is a pleiotropic recombinase protein that has been demonstrated to be implicated strongly in the bacterial drug resistance, survival and pathogenicity. In this minireview, RecA's role in the development of antibiotic resistance and its potential as an antimicrobial drug target are discussed.

Elemente de structură bacteriană și mecanismele transmiterii rezistenței la antibiotice / Elements of bacterial structure and mechanisms of antibiotic resistance transmission

Directory of Open Access Journals (Sweden)

Alexandru O. Doma

2015-12-01

Full Text Available The aim of this bibliographic essay is to refresh the knowledge of veterinarians in the field of therapy and bacterial resistance. Are summarized, in a didactic manner: the bacteria classification, the overall structure of the cell wall, the general characterization of antibiotics, the fundamental modes of action of antibiotics, the main interactions and side phenomena antibiotics and toxic products. Installing and effects of bacterial resistance to antibiotics is presented in detail, being given the basic concepts about resistance mechanisms as: the drug inactivation or misappropriation of the pathway, enzyme target altering or structure, low accumulation of antibiotic resistance in bacterial cells. They are also presented: the natural antibiotic resistance (epigenetic, the gained antibiotic resistance, the genetic adaptation (by mutation and selection and the genetic acquisition. By means of resistance means all the mechanisms by which bacteria can reduce or total inactivate the antimicrobial activity. In this regard are presented: phases of the resistance installation and antibiotics’ modification / inactivation, not being omitted also the trends in the evolution of resistance to antibiotics and environmental impacts analysis, the results of the imprudent using of the anti-infectives (like veterinary antibiotics in soil and water, the antibiotic resistance in the genetic modified crops or the long-term effects on ecosystems and them consequences.

Impact of antibiotic use in adult dairy cows on antimicrobial resistance of veterinary and human pathogens: a comprehensive review.

Science.gov (United States)

Oliver, Stephen P; Murinda, Shelton E; Jayarao, Bhushan M

2011-03-01

Antibiotics have saved millions of human lives, and their use has contributed significantly to improving human and animal health and well-being. Use of antibiotics in food-producing animals has resulted in healthier, more productive animals; lower disease incidence and reduced morbidity and mortality in humans and animals; and production of abundant quantities of nutritious, high-quality, and low-cost food for human consumption. In spite of these benefits, there is considerable concern from public health, food safety, and regulatory perspectives about the use of antimicrobials in food-producing animals. Over the last two decades, development of antimicrobial resistance resulting from agricultural use of antibiotics that could impact treatment of diseases affecting the human population that require antibiotic intervention has become a significant global public health concern. In the present review, we focus on antibiotic use in lactating and nonlactating cows in U.S. dairy herds, and address four key questions: (1) Are science-based data available to demonstrate antimicrobial resistance in veterinary pathogens that cause disease in dairy cows associated with use of antibiotics in adult dairy cows? (2) Are science-based data available to demonstrate that antimicrobial resistance in veterinary pathogens that cause disease in adult dairy cows impacts pathogens that cause disease in humans? (3) Does antimicrobial resistance impact the outcome of therapy? (4) Are antibiotics used prudently in the dairy industry? On the basis of this review, we conclude that scientific evidence does not support widespread, emerging resistance among pathogens isolated from dairy cows to antibacterial drugs even though many of these antibiotics have been used in the dairy industry for treatment and prevention of disease for several decades. However, it is clear that use of antibiotics in adult dairy cows and other food-producing animals does contribute to increased antimicrobial resistance

Comparative Resistance of Bacterial Foodborne Pathogens to Non-thermal Technologies for Food Preservation.

Science.gov (United States)

Cebrián, Guillermo; Mañas, Pilar; Condón, Santiago

2016-01-01

In this paper the resistance of bacterial foodborne pathogens to manosonication (MS), pulsed electric fields (PEFs), high hydrostatic pressure (HHP), and UV-light (UV) is reviewed and compared. The influence of different factors on the resistance of bacterial foodborne pathogens to these technologies is also compared and discussed. Only results obtained under harmonized experimental conditions have been considered. This has allowed us to establish meaningful comparisons and draw significant conclusions. Among the six microorganisms here considered, Staphyloccocus aureus is the most resistant foodborne pathogen to MS and HHP and Listeria monocytogenes to UV. The target microorganism of PEF would change depending on the treatment medium pH. Thus, L. monocytogenes is the most PEF resistant microorganism at neutral pH but Gram-negatives (Escherichia coli, Salmonella spp., Cronobacter sakazakii, Campylobacter jejuni) would display a similar or even higher resistance at acidic pH. It should be noted that, in acidic products, the baroresistance of some E. coli strains would be comparable to that of S. aureus. The factors affecting the resistance of bacterial foodborne pathogens, as well as the magnitude of the effect, varied depending on the technology considered. Inter- and intra-specific differences in microbial resistance to PEF and HHP are much greater than to MS and UV. Similarly, both the pH and aw of the treatment medium highly condition microbial resistance to PEF and HHP but no to MS or UV. Growth phase also drastically affected bacterial HHP resistance. Regarding UV, the optical properties of the medium are, by far, the most influential factor affecting its lethal efficacy. Finally, increasing treatment temperature leads to a significant increase in lethality of the four technologies, what opens the possibility of the development of combined processes including heat. The appearance of sublethally damaged cells following PEF and HHP treatments could also be

Comparative Resistance of Bacterial Foodborne Pathogens to Non-thermal Technologies for Food Preservation

Science.gov (United States)

Cebrián, Guillermo; Mañas, Pilar; Condón, Santiago

2016-01-01

In this paper the resistance of bacterial foodborne pathogens to manosonication (MS), pulsed electric fields (PEFs), high hydrostatic pressure (HHP), and UV-light (UV) is reviewed and compared. The influence of different factors on the resistance of bacterial foodborne pathogens to these technologies is also compared and discussed. Only results obtained under harmonized experimental conditions have been considered. This has allowed us to establish meaningful comparisons and draw significant conclusions. Among the six microorganisms here considered, Staphyloccocus aureus is the most resistant foodborne pathogen to MS and HHP and Listeria monocytogenes to UV. The target microorganism of PEF would change depending on the treatment medium pH. Thus, L. monocytogenes is the most PEF resistant microorganism at neutral pH but Gram-negatives (Escherichia coli, Salmonella spp., Cronobacter sakazakii, Campylobacter jejuni) would display a similar or even higher resistance at acidic pH. It should be noted that, in acidic products, the baroresistance of some E. coli strains would be comparable to that of S. aureus. The factors affecting the resistance of bacterial foodborne pathogens, as well as the magnitude of the effect, varied depending on the technology considered. Inter- and intra-specific differences in microbial resistance to PEF and HHP are much greater than to MS and UV. Similarly, both the pH and aw of the treatment medium highly condition microbial resistance to PEF and HHP but no to MS or UV. Growth phase also drastically affected bacterial HHP resistance. Regarding UV, the optical properties of the medium are, by far, the most influential factor affecting its lethal efficacy. Finally, increasing treatment temperature leads to a significant increase in lethality of the four technologies, what opens the possibility of the development of combined processes including heat. The appearance of sublethally damaged cells following PEF and HHP treatments could also be

COMPARATIVE RESISTANCE OF BACTERIAL FOODBORNE PATHOGENS TO NON-THERMAL TECHNOLOGIES FOR FOOD PRESERVATION

Directory of Open Access Journals (Sweden)

Guillermo eCebrián

2016-05-01

Full Text Available In this paper the resistance of bacterial foodborne pathogens to manosonication (MS, pulsed electric fields (PEF, high hydrostatic pressure (HHP and UV-light (UV is reviewed and compared. The influence of different factors on the resistance of bacterial foodborne pathogens to these technologies is also compared and discussed. Only results obtained under harmonized experimental conditions have been considered. This has allowed us to establish meaningful comparisons and draw significant conclusions. Among the six microorganisms here considered, Staphyloccocus aureus is the most resistant foodborne pathogen to MS and HHP and Listeria monocytogenes to UV. The target microorganism of PEF would change depending on the treatment medium pH. Thus, L. monocytogenes is the most PEF resistant microorganism at neutral pH but Gram-negatives (Escherichia coli, Salmonella spp., Cronobacter sakazakii, Campylobacter jejuni would display a similar or even higher resistance at acidic pH. It should be noted that, in acidic products, the baroresistance of some E. coli strains would be comparable to that of S. aureus. The factors affecting the resistance of bacterial foodborne pathogens, as well as the magnitude of the effect, varied depending on the technology considered. Inter- and intra-specific differences in microbial resistance to PEF and HHP are much greater than to MS and UV. Similarly, both the pH and aw of the treatment medium highly condition microbial resistance to PEF and HHP but no to MS or UV. Growth phase also drastically affected bacterial HHP resistance. Regarding UV, the optical properties of the medium are, by far, the most influential factor affecting its lethal efficacy. Finally, increasing treatment temperature leads to a significant increase in lethality of the four technologies, what opens the possibility of the development of combined processes including heat. The appearance of sublethally damaged cells following PEF and HHP treatments could

PRESENCE OF ENTEROCOCCI IN COW MILK AND THEIR ANTIBIOTIC RESISTANCE

Directory of Open Access Journals (Sweden)

Miroslav Kročko

2010-05-01

Full Text Available Enterococci represent an important part of contaminate microflora in raw milk and dairy products. They constitute significant part of nosocomial pathogens with a remarkable capacity of expressing resistance to several antimicrobial  agents. We aimed to assess occurrence and antibiotic resistance of enterococci in the raw milk samples and pasteurized milk samples. In this study total bacterial count, psychrotrophic count and count of enterococci were determine in raw milk cistern samples, storage tank milk samples and milk samples after pasteurization. A collection of 46 enterococcal isolates were identified and screened for their antibiotic resistance. Isolates of E. faecalis were dominant in raw milk samples (56.5 %. Sensitive to teicoplanine (30 mcg/disk were 97.9 % of enterococcal isolates and 15.2 % isolates were resistant to vankomycin (30 mcg/disk.  

When the most potent combination of antibiotics selects for the greatest bacterial load: the smile-frown transition.

Science.gov (United States)

Pena-Miller, Rafael; Laehnemann, David; Jansen, Gunther; Fuentes-Hernandez, Ayari; Rosenstiel, Philip; Schulenburg, Hinrich; Beardmore, Robert

2013-01-01

Conventional wisdom holds that the best way to treat infection with antibiotics is to 'hit early and hit hard'. A favoured strategy is to deploy two antibiotics that produce a stronger effect in combination than if either drug were used alone. But are such synergistic combinations necessarily optimal? We combine mathematical modelling, evolution experiments, whole genome sequencing and genetic manipulation of a resistance mechanism to demonstrate that deploying synergistic antibiotics can, in practice, be the worst strategy if bacterial clearance is not achieved after the first treatment phase. As treatment proceeds, it is only to be expected that the strength of antibiotic synergy will diminish as the frequency of drug-resistant bacteria increases. Indeed, antibiotic efficacy decays exponentially in our five-day evolution experiments. However, as the theory of competitive release predicts, drug-resistant bacteria replicate fastest when their drug-susceptible competitors are eliminated by overly-aggressive treatment. Here, synergy exerts such strong selection for resistance that an antagonism consistently emerges by day 1 and the initially most aggressive treatment produces the greatest bacterial load, a fortiori greater than if just one drug were given. Whole genome sequencing reveals that such rapid evolution is the result of the amplification of a genomic region containing four drug-resistance mechanisms, including the acrAB efflux operon. When this operon is deleted in genetically manipulated mutants and the evolution experiment repeated, antagonism fails to emerge in five days and antibiotic synergy is maintained for longer. We therefore conclude that unless super-inhibitory doses are achieved and maintained until the pathogen is successfully cleared, synergistic antibiotics can have the opposite effect to that intended by helping to increase pathogen load where, and when, the drugs are found at sub-inhibitory concentrations.

When the most potent combination of antibiotics selects for the greatest bacterial load: the smile-frown transition.

Directory of Open Access Journals (Sweden)

Rafael Pena-Miller

Full Text Available Conventional wisdom holds that the best way to treat infection with antibiotics is to 'hit early and hit hard'. A favoured strategy is to deploy two antibiotics that produce a stronger effect in combination than if either drug were used alone. But are such synergistic combinations necessarily optimal? We combine mathematical modelling, evolution experiments, whole genome sequencing and genetic manipulation of a resistance mechanism to demonstrate that deploying synergistic antibiotics can, in practice, be the worst strategy if bacterial clearance is not achieved after the first treatment phase. As treatment proceeds, it is only to be expected that the strength of antibiotic synergy will diminish as the frequency of drug-resistant bacteria increases. Indeed, antibiotic efficacy decays exponentially in our five-day evolution experiments. However, as the theory of competitive release predicts, drug-resistant bacteria replicate fastest when their drug-susceptible competitors are eliminated by overly-aggressive treatment. Here, synergy exerts such strong selection for resistance that an antagonism consistently emerges by day 1 and the initially most aggressive treatment produces the greatest bacterial load, a fortiori greater than if just one drug were given. Whole genome sequencing reveals that such rapid evolution is the result of the amplification of a genomic region containing four drug-resistance mechanisms, including the acrAB efflux operon. When this operon is deleted in genetically manipulated mutants and the evolution experiment repeated, antagonism fails to emerge in five days and antibiotic synergy is maintained for longer. We therefore conclude that unless super-inhibitory doses are achieved and maintained until the pathogen is successfully cleared, synergistic antibiotics can have the opposite effect to that intended by helping to increase pathogen load where, and when, the drugs are found at sub-inhibitory concentrations.

MICROBIAL PROFILE AND ANTIBIOTIC RESISTANCE PATTERN OF THE BACTERIAL ISOLATES IN A TERTIARY CARE PSYCHIATRY HOSPITAL

Directory of Open Access Journals (Sweden)

Jyoti

2015-11-01

Full Text Available BACKGROUND: Antibiotic resistance is a challenge for effective management of infections as it increases the morbidity, mortality and costs of treating infectious diseases. AIMS: This study was aimed to obtain the profile of the bacterial isolates and their antibiotic resistance pattern. SETTINGS AND DESIGN: It is a cross sectional study carried out in a tertiary care psychiatry hospital in India. MATERIALS AND METHODS: Isolation and identification of the isolates were done by standard methods. Susceptibility patterns were checked by Kirby Bauer disc diffusion method. STATISTICAL ANALYSIS USED: Statistical analysis was done by using SPSS 16.0 version to calculate the frequencies as well as for cross tabulation. RESULTS: Significant bacterial growth observed in 43(25.6% samples, of which 39(90.7% showed resistant to at least one of the antibiotics used and 36(83.7% were multi-drug resistant. Gram negative organism accounted for the 25(58.14% of total significant isolates, Escherichia coli being the highest (76% in this group. Among multi-drug resistant (MDR isolates E.coli was the highest (44.4% and imipenem resistance was also observed in 1(5.3% of 19 E.coli isolates. Among the 43 isolates 18(41.86% were Gram positive with Streptococcus spp. showing incidence of 41.7% among the total MDR isolates. CONCLUSION: Increasing incidence of MDR strains seen in the population requires continuous monitoring and a restricted use of antibiotics to keep a check on resistance pattern, for effective treatment plan.

Thermus Thermophilus as a Model System for the Study of Ribosomal Antibiotic Resistance

Science.gov (United States)

Gregory, Steven T.

2018-03-01

Ribosomes are the intracellular ribonucleoprotein machines responsible for the translation of mRNA sequence into protein sequence. As an essential cell component, the ribosome is the target of numerous antibiotics that bind to critical functional sites to impair protein synthesis. Mutations causing resistance to antibiotics arise in antibiotic binding sites, and an understanding of the basis of resistance will be an essential component of efforts to develop new antibiotics by rational drug design. We have identified a number of antibiotic-resistance mutations in ribosomal genes of the thermophilic bacterium Thermus thermophilus. This species offers two primary advantages for examining the structural basis of antibiotic-resistance, in particular, its potential for genetic manipulation and the suitability of its ribosomes for analysis by X-ray crystallography. Mutations we have identified in this organism are in many instances identical to those found in other bacterial species, including important pathogens, a result of the extreme conservation of ribosome functional sites. Here I summarize the advantages of this organism as a model system to study antibiotic-resistance mechanisms at the molecular level.

The Prehistory of Antibiotic Resistance.

Science.gov (United States)

Perry, Julie; Waglechner, Nicholas; Wright, Gerard

2016-06-01

Antibiotic resistance is a global problem that is reaching crisis levels. The global collection of resistance genes in clinical and environmental samples is the antibiotic "resistome," and is subject to the selective pressure of human activity. The origin of many modern resistance genes in pathogens is likely environmental bacteria, including antibiotic producing organisms that have existed for millennia. Recent work has uncovered resistance in ancient permafrost, isolated caves, and in human specimens preserved for hundreds of years. Together with bioinformatic analyses on modern-day sequences, these studies predict an ancient origin of resistance that long precedes the use of antibiotics in the clinic. Understanding the history of antibiotic resistance is important in predicting its future evolution. Copyright © 2016 Cold Spring Harbor Laboratory Press; all rights reserved.

Increasing antibiotic resistance in preservative-tolerant bacterial strains isolated from cosmetic products.

Science.gov (United States)

Orús, Pilar; Gomez-Perez, Laura; Leranoz, Sonia; Berlanga, Mercedes

2015-03-01

To ensure the microbiological quality, consumer safety and organoleptic properties of cosmetic products, manufacturers need to comply with defined standards using several preservatives and disinfectants. A drawback regarding the use of these preservatives is the possibility of generating cross-insusceptibility to other disinfectants or preservatives, as well as cross resistance to antibiotics. Therefore, the objective of this study was to understand the adaptive mechanisms of Enterobacter gergoviae, Pseudomonas putida and Burkholderia cepacia that are involved in recurrent contamination in cosmetic products containing preservatives. Diminished susceptibility to formaldehyde-donors was detected in isolates but not to other preservatives commonly used in the cosmetics industry, although increasing resistance to different antibiotics (β-lactams, quinolones, rifampicin, and tetracycline) was demonstrated in these strains when compared with the wild-type strain. The outer membrane protein modifications and efflux mechanism activities responsible for the resistance trait were evaluated. The development of antibiotic-resistant microorganisms due to the selective pressure from preservatives included in cosmetic products could be a risk for the emergence and spread of bacterial resistance in the environment. Nevertheless, the large contribution of disinfection and preservation cannot be denied in cosmetic products. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

Comparison of antibiotic resistance, virulence gene profiles, and pathogenicity of methicillin-resistant and methicillin-susceptible Staphylococcus aureus using a Caenorhabditis elegans infection model

Science.gov (United States)

Thompson, Terissa; Brown, Paul D

2014-01-01

Objectives: This study compared the presence of 35 virulence genes, resistance phenotypes to 11 anti-staphylococcal antibiotics, and pathogenicity in methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA). Methods: Multiplex PCR analysis was used to differentiate Staphylococcus aureus isolates (n = 102) based on characterization of the Staphylococcal Cassette Chromosome mec (SCCmec). Singleplex and multiplex PCR assays targeting 35 virulence determinants were used to analyze the virulence repertoire of S. aureus. In vitro activities of the antibiotics were determined by the disk-diffusion method. The pathogenicity of representative isolates was assessed using Caenorhabditis elegans survival assays. Significance in virulence distribution and antibiotic resistance phenotypes was assessed using the Chi-squared tests. Kaplan–Meier survival estimates were used to analyze nematode survival and significance of survival rates evaluated using the log-rank test. Results: Except for sei (staphylococcal enterotoxin I) (P  =  0.027), all other virulence genes were not significantly associated with MRSA. Resistance to clindamycin (P  =  0.03), tetracycline (P  =  0.048), trimethoprim/sulfamethoxazole (P  =  0.038), and oxacillin (P  =  0.004) was significantly associated with MRSA. Survival assay showed MSSA having a lower median lifespan of 3 days than MRSA that had a median lifespan of 6 days. The difference in the killing time of MRSA and MSSA was significant (P virulence genes. The quicker killing potential of MSSA compared to MRSA suggests that carriage of virulence determinants per se does not determine pathogenicity in S. aureus. Pathogenicity is impacted by other factors, possibly antibiotic resistance. PMID:25319852

Pathogenicity determinants and antibiotic resistance profiles of enterococci from foods of animal origin in Turkey.

Science.gov (United States)

Elal Mus, Tulay; Cetinkaya, Figen; Cibik, Recep; Soyutemiz, Gul Ece; Simsek, Husniye; Coplu, Nilay

2017-12-01

In this study, the presence of genes responsible for the pathogenicity and antibiotic resistance profile of enterococci isolated from various foodstuffs of animal origin was investigated. The percentage prevalence of enterococci was 54.1% (203/375) and the average count was found to be 3.81 log cfu/ml-g. Species-specific primers revealed Enterococcus faecalis as the predominant species carrying one or more virulence-associated traits of efa, gelE, ace, esp and agg genetic markers. Only one E. faecium isolate (from milk) was positive for the esp gene. Regarding antibiotic resistance, the highest frequency of resistance was observed for tetracycline (21.7%), followed by quinupristin/dalfopristin (13.3%), ciprofloxacin (2.0%), penicillin (2.0%), linezolid (1.0%), ampicillin (1.0%), streptomycin (1.0%), and gentamicin (0.5%). Enterococcus faecalis showed a higher prevalence of antibiotic resistance than other enterococci. The percentage of multidrug resistance among the isolates was 3.4%. Twenty-nine E. faecalis isolates (26.6%) carrying one of the virulence-associated traits were at the same time resistant to at least one antibiotic. Our results show that foods of animal origin, including ready-to-eat products, may be reservoirs of antibiotic-resistant and potentially virulent enterococci.

Strategies to Minimize Antibiotic Resistance

Directory of Open Access Journals (Sweden)

Sang Hee Lee

2013-09-01

Full Text Available Antibiotic resistance can be reduced by using antibiotics prudently based on guidelines of antimicrobial stewardship programs (ASPs and various data such as pharmacokinetic (PK and pharmacodynamic (PD properties of antibiotics, diagnostic testing, antimicrobial susceptibility testing (AST, clinical response, and effects on the microbiota, as well as by new antibiotic developments. The controlled use of antibiotics in food animals is another cornerstone among efforts to reduce antibiotic resistance. All major resistance-control strategies recommend education for patients, children (e.g., through schools and day care, the public, and relevant healthcare professionals (e.g., primary-care physicians, pharmacists, and medical students regarding unique features of bacterial infections and antibiotics, prudent antibiotic prescribing as a positive construct, and personal hygiene (e.g., handwashing. The problem of antibiotic resistance can be minimized only by concerted efforts of all members of society for ensuring the continued efficiency of antibiotics.

Detection of selected antibiotic resistance genes using multiplex PCR assay in mastitis pathogens in the Czech Republic

Directory of Open Access Journals (Sweden)

Vladimir Pyatov

2017-01-01

Full Text Available The aim of this research was to develop multiplex polymerase chain reaction assays for the detection of aminoglycoside (strA, strB, sulphonamide (sulI, sulII, tetracycline (tetA, tetB, tetK, tetM, tetO, macrolide and lincosamide (msrA, ermA, ermB, ermC, mefA/E genes of resistance in mastitis pathogens (Escherichia coli, Staphylococcus aureus, Streptococcus uberis, Streptococcus agalactiae and Streptococcus dysgalactiae. Applying the established assays, we investigated the distribution of antibiotic resistance genes in the above mentioned species isolated from milk samples in the Czech Republic. Each assay consisted of seven pairs of primers. Six of them amplified fragments of antibiotic resistance genes and one pair a fragment of a species specific gene. Polymerase chain reaction conditions were optimized to amplify seven gene fragments simultaneously in one reaction. In total, 249 isolates were used, among which 111 were positive for E. coli, 52 for S. aureus and 86 for Streptococcus spp. The majority (60.2% of bacteria carried at least one antibiotic resistance gene and 44.6% were multidrug-resistant. The designed multiplex polymerase chain reaction assays may be applied as diagnostic method to replace or complement standard techniques of antibiotic susceptibility testing in the mentioned pathogens.

Antibiotic resistance patterns of pediatric community-acquired urinary infections

Directory of Open Access Journals (Sweden)

Eliana Biondi Medeiros Guidoni

Full Text Available Knowledge about antimicrobial resistance patterns of the etiological agents of urinary tract infections (UTIs is essential for appropriate therapy. Urinary isolates from symptomatic UTI cases attended at Santa Casa University Hospital of São Paulo from August 1986 to December 1989 and August 2004 to December 2005 were identified by conventional methods. Antimicrobial resistance testing was performed by Kirby Bauer's disc diffusion method. Among the 257 children, E. coli was found in 77%. A high prevalence of resistance was observed against ampicillin and TMP/SMX (55% and 51%. The antibiotic resistance rates for E. coli were: nitrofurantoin (6%, nalidixic acid (14%, 1st generation cephalosporin (13%, 3rd generation cephalosporins (5%, aminoglycosides (2%, norfloxacin (9% and ciprofloxacin (4%. We found that E. coli was the predominant bacterial pathogen of community-acquired UTIs. We also detected increasing resistance to TMP/SMX among UTI pathogens in this population.

Exposure of the grass shrimp, Palaemonetes pugio, to antimicrobial compounds affects associated Vibrio bacterial density and development of antibiotic resistance.

Science.gov (United States)

DeLorenzo, M E; Brooker, J; Chung, K W; Kelly, M; Martinez, J; Moore, J G; Thomas, M

2016-04-01

Antimicrobial compounds are widespread, emerging contaminants in the aquatic environment and may threaten ecosystem and human health. This study characterized effects of antimicrobial compounds common to human and veterinary medicine, aquaculture, and consumer personal care products [erythromycin (ERY), sulfamethoxazole (SMX), oxytetracycline (OTC), and triclosan (TCS)] in the grass shrimp Palaemonetes pugio. The effects of antimicrobial treatments on grass shrimp mortality and lipid peroxidation activity were measured. The effects of antimicrobial treatments on the bacterial community of the shrimp were then assessed by measuring Vibrio density and testing bacterial isolates for antibiotic resistance. TCS (0.33 mg/L) increased shrimp mortality by 37% and increased lipid peroxidation activity by 63%. A mixture of 0.33 mg/L TCS and 60 mg/L SMX caused a 47% increase in shrimp mortality and an 88% increase in lipid peroxidation activity. Exposure to SMX (30 mg/L or 60 mg/L) alone and to a mixture of SMX/ERY/OTC did not significantly affect shrimp survival or lipid peroxidation activity. Shrimp exposure to 0.33 mg/L TCS increased Vibrio density 350% as compared to the control whereas SMX, the SMX/TCS mixture, and the mixture of SMX/ERY/OTC decreased Vibrio density 78-94%. Increased Vibrio antibiotic resistance was observed for all shrimp antimicrobial treatments except for the mixture of SMX/ERY/OTC. Approximately 87% of grass shrimp Vibrio isolates displayed resistance to TCS in the control treatment suggesting a high level of TCS resistance in environmental Vibrio populations. The presence of TCS in coastal waters may preferentially increase the resistance and abundance of pathogenic bacteria. These results indicate the need for further study into the potential interactions between antimicrobials, aquatic organisms, and associated bacterial communities. © 2014 Wiley Periodicals, Inc.

Strain Dependent Genetic Networks for Antibiotic-Sensitivity in a Bacterial Pathogen with a Large Pan-Genome.

Directory of Open Access Journals (Sweden)

Tim van Opijnen

2016-09-01

Full Text Available The interaction between an antibiotic and bacterium is not merely restricted to the drug and its direct target, rather antibiotic induced stress seems to resonate through the bacterium, creating selective pressures that drive the emergence of adaptive mutations not only in the direct target, but in genes involved in many different fundamental processes as well. Surprisingly, it has been shown that adaptive mutations do not necessarily have the same effect in all species, indicating that the genetic background influences how phenotypes are manifested. However, to what extent the genetic background affects the manner in which a bacterium experiences antibiotic stress, and how this stress is processed is unclear. Here we employ the genome-wide tool Tn-Seq to construct daptomycin-sensitivity profiles for two strains of the bacterial pathogen Streptococcus pneumoniae. Remarkably, over half of the genes that are important for dealing with antibiotic-induced stress in one strain are dispensable in another. By confirming over 100 genotype-phenotype relationships, probing potassium-loss, employing genetic interaction mapping as well as temporal gene-expression experiments we reveal genome-wide conditionally important/essential genes, we discover roles for genes with unknown function, and uncover parts of the antibiotic's mode-of-action. Moreover, by mapping the underlying genomic network for two query genes we encounter little conservation in network connectivity between strains as well as profound differences in regulatory relationships. Our approach uniquely enables genome-wide fitness comparisons across strains, facilitating the discovery that antibiotic responses are complex events that can vary widely between strains, which suggests that in some cases the emergence of resistance could be strain specific and at least for species with a large pan-genome less predictable.

Molecular and Conventional Analysis of Acute Diarrheal Isolates Identifies Epidemiological Trends, Antibiotic Resistance and Virulence Profiles of Common Enteropathogens in Shanghai

Directory of Open Access Journals (Sweden)

Feng Yang

2018-02-01

Full Text Available Objective: To investigate prevalence of acute diarrhea in Shanghai and analyze virulence associated-genes and antibiotic resistance of major enteropathogens using combination of conventional and molecular epidemiology methods.Method: The 412 stool specimens were obtained by systematic sampling from diarrhea patients throughout entire year 2016. Bacterial and viral pathogens were identified and bacterial isolates were cultured and screened for antibiotic resistance profiles. Two most prevalent bacteria, Vibrio parahaemolyticus and Salmonella were further typed by multi-locus sequence typing (MLST and analyzed for presence of virulence-associated genes. The association between virulence genes, resistance phenotypes and genetic diversities was analyzed.Results: Among stool specimens testing positive for pathogens (23.1%, 59 bacterial and 36 viral pathogens were identified. V. parahaemolyticus (27/412, 6.6%, Salmonella (23/412, 5.6% and norovirus GII (21/412, 5.1% were three most-commonly found. Most bacterial isolates exhibited high levels of antibiotic resistance with high percentage of MDR. The drug resistance rates of V. parahaemolyticus and Salmonella isolates to cephalosporins were high, such as 100.0 and 34.8% to CFX, 55.6 and 43.4% to CTX, 92.6 and 95.7% to CXM, respectively. The most common resistance combination of V. parahaemolyticus and Salmonella was cephalosporins and quinolone. The dominant sequence types (STs of V. parahaemolyticus and Salmonella were ST3 (70.4% and ST11 (43.5%, respectively. The detection rates of virulence genes in V. parahaemolyticus were tlh (100% and tdh (92.6%, without trh and ureR. Most of the Salmonella isolates were positive for the Salmonella pathogenicity islands (SPIs genes (87–100%, and some for Salmonella plasmid virulence (SPV genes (34.8% for spvA and spvB, 43.5% for spvC. In addition, just like the drug resistance, virulence genes exhibited wide-spread distribution among the different STs albeit

Bacterial flora and antibiotic resistance from eggs of green turtles Chelonia mydas: An indication of polluted effluents

International Nuclear Information System (INIS)

Al-Bahry, Saif; Mahmoud, Ibrahim; Elshafie, Abdulkader; Al-Harthy, Asila; Al-Ghafri, Sabha; Al-Amri, Issa; Alkindi, Abdulaziz

2009-01-01

Sea turtles migrate to various habitats where they can be exposed to different pollutants. Bacteria were collected from turtle eggs and their resistance to antibiotics was used as pollutant bio-indicators of contaminated effluents. Eggs were collected randomly from turtles when they were laying their eggs. A total of 90 eggs were collected and placed into sterile plastic bags (3 eggs/turtle) during June-December of 2003. The bacteria located in the eggshell, albumen and yolk were examined, and 42% of the eggs were contaminated with 10 genera of bacteria. Pseudomonas spp. were the most frequent isolates. The albumen was found to be the part of the egg to be the least contaminated by bacterial infection. Bacterial isolates tested with 14 antibiotics showed variations in resistance. Resistance to ampicillin was the highest. The presence of antibiotic resistant bacteria in eggs indicates that the green turtle populations were subjected to polluted effluents during some of their migratory routes and feeding habitats. Scanning electron microscopy revealed that Salmonella typhimurium penetrated all eggshell layers.

Host range of antibiotic resistance genes in wastewater treatment plant influent and effluent.

Science.gov (United States)

Hultman, Jenni; Tamminen, Manu; Pärnänen, Katariina; Cairns, Johannes; Karkman, Antti; Virta, Marko

2018-04-01

Wastewater treatment plants (WWTPs) collect wastewater from various sources for a multi-step treatment process. By mixing a large variety of bacteria and promoting their proximity, WWTPs constitute potential hotspots for the emergence of antibiotic resistant bacteria. Concerns have been expressed regarding the potential of WWTPs to spread antibiotic resistance genes (ARGs) from environmental reservoirs to human pathogens. We utilized epicPCR (Emulsion, Paired Isolation and Concatenation PCR) to detect the bacterial hosts of ARGs in two WWTPs. We identified the host distribution of four resistance-associated genes (tetM, int1, qacEΔ1and blaOXA-58) in influent and effluent. The bacterial hosts of these resistance genes varied between the WWTP influent and effluent, with a generally decreasing host range in the effluent. Through 16S rRNA gene sequencing, it was determined that the resistance gene carrying bacteria include both abundant and rare taxa. Our results suggest that the studied WWTPs mostly succeed in decreasing the host range of the resistance genes during the treatment process. Still, there were instances where effluent contained resistance genes in bacterial groups not carrying these genes in the influent. By permitting exhaustive profiling of resistance-associated gene hosts in WWTP bacterial communities, the application of epicPCR provides a new level of precision to our resistance gene risk estimates.

Boar semen bacterial contamination in Italy and antibiotic efficacy in a modified extender

Directory of Open Access Journals (Sweden)

Carla Bresciani

2014-02-01

Full Text Available The aims of the study were to identify microbial flora in boar semen under field conditions in northern Italy, to investigate antibiotic resistance and sensitivity of isolated bacteria, and to evaluate elimination of bacteria after storage in two types of extenders added with different antibiotics (amikacin vs gentamicin. A total of 60 boars were collected in 13 pig farms. Bacteriological and mycological investigations were performed immediately on raw semen samples, then at 48 and 120 h of storage on semen diluted randomly in a new short-term modified extender (ME-S or in a commercial one (CRONOSTM. Bacterial contamination was found in 63% of raw semen samples and different bacterial species were isolated: E.coli, Serratia marcescens, Staphylococcus epidermidis and aureus, Proteus spp., Streptococcus spp. and Pseudomonas aeruginosa. E. coli was the most isolated contaminant (53%; Pseudomonas aeruginosa was found only in one semen sample. The analysis of variance of factors affecting contamination levels was significant for the farm of origin (P<0.05 and not significant for the breed. Antibiotic resistance of these bacteria was assessed using different antibiotics. Significant differences (P<0.05 between observed and expected frequencies of bacterial isolates resistant or not to the antibiotics contained in the extenders were found. At 48 h of storage a reduction of aerobic contamination was found after ME-S dilution by 85.3% and after CRONOSTM by 63.8%. This paper proved the presence of pathogenic bacteria in semen. We thus believe it is highly advisable to perform periodic microbiological screening of boar semen in the swine industry to avoid the use of low sperm quality.

Selection of antibiotic resistance at very low antibiotic concentrations.

Science.gov (United States)

Sandegren, Linus

2014-05-01

Human use of antibiotics has driven the selective enrichment of pathogenic bacteria resistant to clinically used drugs. Traditionally, the selection of resistance has been considered to occur mainly at high, therapeutic levels of antibiotics, but we are now beginning to understand better the importance of selection of resistance at low levels of antibiotics. The concentration of an antibiotic varies in different body compartments during treatment, and low concentrations of antibiotics are found in sewage water, soils, and many water environments due to natural production and contamination from human activities. Selection of resistance at non-lethal antibiotic concentrations (below the wild-type minimum inhibitory concentration) occurs due to differences in growth rate at the particular antibiotic concentration between cells with different tolerance levels to the antibiotic. The minimum selective concentration for a particular antibiotic is reached when its reducing effect on growth of the susceptible strain balances the reducing effect (fitness cost) of the resistance determinant in the resistant strain. Recent studies have shown that resistant bacteria can be selected at concentrations several hundred-fold below the lethal concentrations for susceptible cells. Resistant mutants selected at low antibiotic concentrations are generally more fit than those selected at high concentrations but can still be highly resistant. The characteristics of selection at low antibiotic concentrations, the potential clinical problems of this mode of selection, and potential solutions will be discussed.

A new antibiotic kills pathogens without detectable resistance.

Science.gov (United States)

Ling, Losee L; Schneider, Tanja; Peoples, Aaron J; Spoering, Amy L; Engels, Ina; Conlon, Brian P; Mueller, Anna; Schäberle, Till F; Hughes, Dallas E; Epstein, Slava; Jones, Michael; Lazarides, Linos; Steadman, Victoria A; Cohen, Douglas R; Felix, Cintia R; Fetterman, K Ashley; Millett, William P; Nitti, Anthony G; Zullo, Ashley M; Chen, Chao; Lewis, Kim

2015-01-22

Antibiotic resistance is spreading faster than the introduction of new compounds into clinical practice, causing a public health crisis. Most antibiotics were produced by screening soil microorganisms, but this limited resource of cultivable bacteria was overmined by the 1960s. Synthetic approaches to produce antibiotics have been unable to replace this platform. Uncultured bacteria make up approximately 99% of all species in external environments, and are an untapped source of new antibiotics. We developed several methods to grow uncultured organisms by cultivation in situ or by using specific growth factors. Here we report a new antibiotic that we term teixobactin, discovered in a screen of uncultured bacteria. Teixobactin inhibits cell wall synthesis by binding to a highly conserved motif of lipid II (precursor of peptidoglycan) and lipid III (precursor of cell wall teichoic acid). We did not obtain any mutants of Staphylococcus aureus or Mycobacterium tuberculosis resistant to teixobactin. The properties of this compound suggest a path towards developing antibiotics that are likely to avoid development of resistance.

Rhizosphere-associated Pseudomonas induce systemic resistance to herbivores at the cost of susceptibility to bacterial pathogens.

Science.gov (United States)

Haney, Cara H; Wiesmann, Christina L; Shapiro, Lori R; Melnyk, Ryan A; O'Sullivan, Lucy R; Khorasani, Sophie; Xiao, Li; Han, Jiatong; Bush, Jenifer; Carrillo, Juli; Pierce, Naomi E; Ausubel, Frederick M

2017-10-31

Plant-associated soil microbes are important mediators of plant defence responses to diverse above-ground pathogen and insect challengers. For example, closely related strains of beneficial rhizosphere Pseudomonas spp. can induce systemic resistance (ISR), systemic susceptibility (ISS) or neither against the bacterial foliar pathogen Pseudomonas syringae pv. tomato DC3000 (Pto DC3000). Using a model system composed of root-associated Pseudomonas spp. strains, the foliar pathogen Pto DC3000 and the herbivore Trichoplusia ni (cabbage looper), we found that rhizosphere-associated Pseudomonas spp. that induce either ISS and ISR against Pto DC3000 all increased resistance to herbivory by T. ni. We found that resistance to T. ni and resistance to Pto DC3000 are quantitative metrics of the jasmonic acid (JA)/salicylic acid (SA) trade-off and distinct strains of rhizosphere-associated Pseudomonas spp. have distinct effects on the JA/SA trade-off. Using genetic analysis and transcriptional profiling, we provide evidence that treatment of Arabidopsis with Pseudomonas sp. CH267, which induces ISS against bacterial pathogens, tips the JA/SA trade-off towards JA-dependent defences against herbivores at the cost of a subset of SA-mediated defences against bacterial pathogens. In contrast, treatment of Arabidopsis with the ISR strain Pseudomonas sp. WCS417 disrupts JA/SA antagonism and simultaneously primes plants for both JA- and SA-mediated defences. Our findings show that ISS against the bacterial foliar pathogens triggered by Pseudomonas sp. CH267, which is a seemingly deleterious phenotype, may in fact be an adaptive consequence of increased resistance to herbivory. Our work shows that pleiotropic effects of microbiome modulation of plant defences are important to consider when using microbes to modify plant traits in agriculture. © 2017 John Wiley & Sons Ltd.

Changes in Bacterial Resistance Patterns of Pediatric Urinary Tract Infections and Rationale for Empirical Antibiotic Therapy.

Science.gov (United States)

Gökçe, İbrahim; Çiçek, Neslihan; Güven, Serçin; Altuntaş, Ülger; Bıyıklı, Neşe; Yıldız, Nurdan; Alpay, Harika

2017-09-29

The causative agent spectrum and resistance patterns of urinary tract infections in children are affected by many factors. To demonstrate antibiotic resistance in urinary tract infections and changing ratio in antibiotic resistance by years. Retrospective cross-sectional study. We analysed antibiotic resistance patterns of isolated Gram (-) bacteria during the years 2011-2014 (study period 2) in children with urinary tract infections. We compared these findings with data collected in the same centre in 2001-2003 (study period 1). Four hundred and sixty-five uncomplicated community-acquired Gram (-) urinary tract infections were analysed from 2001-2003 and 400 from 2011-2014. Sixty-one percent of patients were female (1.5 girls : 1 boy). The mean age of children included in the study was 3 years and 9 months. Escherichia coli was the predominant bacteria isolated during both periods of the study (60% in study period 1 and 73% in study period 2). Bacteria other than E. coli demonstrated a higher level of resistance to all of the antimicrobials except trimethoprim-sulfamethoxazole than E. coli bacteria during the years 2011-2014. In our study, we found increasing resistance trends of urinary pathogens for cefixime (from 1% to 15%, pUrinary pathogens showed a decreasing trend for nitrofurantoin (from 17% to 7%, p=0.0001). No significant trends were detected for ampicillin (from 69% to 71%), amoxicillin-clavulanate (from 44% to 43%), cefazolin (from 39% to 32%), trimethoprim-sulfamethoxazole (from 32% to 31%), cefuroxime (from 21% to 18%) and ceftriaxone (from 10% to 14%) between the two periods (p>0.05). In childhood urinary tract infections, antibiotic resistance should be evaluated periodically and empiric antimicrobial therapy should be decided according to antibiotic sensitivity results.

Pathogen- and host-directed anti-inflammatory activities of macrolide antibiotics.

Science.gov (United States)

Steel, Helen C; Theron, Annette J; Cockeran, Riana; Anderson, Ronald; Feldman, Charles

2012-01-01

Macrolide antibiotics possess several, beneficial, secondary properties which complement their primary antimicrobial activity. In addition to high levels of tissue penetration, which may counteract seemingly macrolide-resistant bacterial pathogens, these agents also possess anti-inflammatory properties, unrelated to their primary antimicrobial activity. Macrolides target cells of both the innate and adaptive immune systems, as well as structural cells, and are beneficial in controlling harmful inflammatory responses during acute and chronic bacterial infection. These secondary anti-inflammatory activities of macrolides appear to be particularly effective in attenuating neutrophil-mediated inflammation. This, in turn, may contribute to the usefulness of these agents in the treatment of acute and chronic inflammatory disorders of both microbial and nonmicrobial origin, predominantly of the airways. This paper is focused on the various mechanisms of macrolide-mediated anti-inflammatory activity which target both microbial pathogens and the cells of the innate and adaptive immune systems, with emphasis on their clinical relevance.

Antibiotic resistance in conjunctival and enteric bacterial flora in raptors housed in a zoological garden.

Science.gov (United States)

Sala, Andrea; Taddei, Simone; Santospirito, Davide; Sandri, Camillo; Magnone, William; Cabassi, Clotilde S

2016-11-01

Antimicrobial resistance (AMR) in a wide range of infectious agents is a growing public health threat. Birds of prey are considered indicators of the presence of AMR bacteria in their ecosystem because of their predatory behaviour. Only few data are reported in the literature on AMR strains isolated from animals housed in zoos and none about AMR in raptors housed in zoological gardens. This study investigated the antibiotic sensitivity profile of the isolates obtained from the conjunctival and cloacal bacterial flora of 14 healthy birds of prey, 6 Accipitriformes , 3 Falconiformes and 5 Strigiformes , housed in an Italian zoological garden. Staphylococcus spp. was isolated from 50% of the conjunctival swabs, with S. xylosus as the most common species. From cloacal swabs, Escherichia coli was cultured from all animals, while Klebsiella spp. and Proteus spp. were isolated from a smaller number of birds. Worthy of note is the isolation of Escherichia fergusonii and Serratia odorifera , rarely isolated from raptors. Staphylococci were also isolated. All the isolates were multidrug resistant (MDR). To the author's knowledge, this is the first report regarding the presence of MDR strains within raptors housed in a zoological garden. Since resistance genes can be transferred to other pathogenic bacteria, this represents a potential hazard for the emergence of new MDR pathogens. In conclusion, the obtained data could be useful for ex-situ conservation programmes aimed to preserve the health of the endangered species housed in a zoo.

[Antibiotic therapy of hospital-acquired pneumonia and its pharmacoeconomics].

Science.gov (United States)

Kolář, Milan; Htoutou Sedláková, Miroslava; Urbánek, Karel; Uvízl, Radomír; Adamus, Milan; Imwensi, O P

2016-03-01

Important hospital-acquired infections include pneumonia, mainly because of the increasing resistance of bacterial pathogens to antimicrobials and the associated potential failure of antibiotic therapy. The present study aimed at determining the most frequent etiological agents of hospital-acquired pneumonia (HAP) and assessing the relationship between 30-day mortality and adequacy of antibiotic therapy. Based on the obtained information, optimal patterns of antibiotic therapy were to be defined, including a pharmacoeconomic perspective. In patients with clinically confirmed HAP, bacterial etiological agents were identified, their susceptibility to antimicrobials was determined and statistical methods were used to assess the relationship between adequacy of antibiotic therapy and 30-day mortality. The study comprised 68 patients with clinically confirmed HAP. The most common etiological agents were strains of Pseudomonas aeruginosa (30.8 %), Klebsiella pneumoniae (23.1 %) and Burkholderia cepacia complex (15.4 %). Gram-negative bacteria accounted for 86.5 % of all bacterial pathogens. The overall mortality reached 42.5 %. In the subgroup of patients with inadequate antibiotic therapy, 30-day mortality was significantly higher (83.3 %) than in the subgroup with adequate therapy (30.0 %; p = 0.002). The risk for 30-day mortality was 2.78 times higher in case of inadequate antibiotic therapy (95%CI: 1.52-5.07). The proportion of Pseudomonas aeruginosa strains was significantly higher in the subgroup of patients with inadequate antibiotic therapy than in those with adequate therapy (67 % vs. 27 %; p = 0.032). Results of the present study suggest a significant relationship between mortality of patients with HAP and ineffective antibiotic therapy due to resistance of the bacterial pathogen. Thus, it is clear that initial antibiotic therapy must be based on qualified assumption of sufficient activity against the most common bacterial pathogens and results of surveillance

Transfer of Antibiotic Resistance in Staphylococcus aureus

DEFF Research Database (Denmark)

Haaber, Jakob; Penadés, José R; Ingmer, Hanne

2017-01-01

Staphylococcus aureus is a serious human pathogen with remarkable adaptive powers. Antibiotic-resistant clones rapidly emerge mainly by acquisition of antibiotic-resistance genes from other S. aureus strains or even from other genera. Transfer is mediated by a diverse complement of mobile genetic...... of plasmids that can be transferred by conjugation and the efficiency with which transduction occurs. Here, we review the main routes of antibiotic resistance gene transfer in S. aureus in the context of its biology as a human commensal and a life-threatening pathogen. Staphylococcus aureus cells...... are effective in exchanging mobile genetic elements, including antibiotic-resistance genes.During colonization or infection of host organisms, the exchange appears to be particularly effective.Bacteriophage-mediated transfer involves both transduction and autotransduction, which may enable lysogenic S. aureus...

[Enzymes for disrupting bacterial communication, an alternative to antibiotics?

Science.gov (United States)

Rémy, B; Plener, L; Elias, M; Daudé, D; Chabrière, E

2016-11-01

Quorum sensing (QS) is used by bacteria to communicate and synchronize their actions according to the cell density. In this way, they produce and secrete in the surrounding environment small molecules dubbed autoinducers (AIs) that regulate the expression of certain genes. The phenotypic traits regulated by QS are diverse and include pathogenicity, biofilm formation or resistance to anti-microbial treatments. The strategy, aiming at disrupting QS, known as quorum quenching (QQ), has emerged to counteract bacterial virulence and involves QS-inhibitors (QSI) or QQ-enzymes degrading AIs. Differently from antibiotics, QQ aims at blocking cell signaling and does not alter bacterial survival. This considerably decreases the selection pressure as compared to bactericide treatments and may reduce the occurrence of resistance mechanisms. QQ-enzymes are particularly appealing as they may disrupt molecular QS-signal without entering the cell and in a catalytic way. This review covers several aspects of QQ-based medical applications and the potential subsequent emergence of resistance is discussed. Copyright © 2016 Académie Nationale de Pharmacie. All rights reserved.

The Shared Antibiotic Resistome of Soil Bacteria and Human Pathogens

DEFF Research Database (Denmark)

Forsberg, Kevin J.; Reyes, Alejandro; Wang, Bin

2012-01-01

protocol to assemble short-read sequence data after antibiotic selection experiments, using 12 different drugs in all antibiotic classes, and compared antibiotic resistance gene sequences between soil bacteria and clinically occurring pathogens. Sixteen sequences, representing seven gene products, were...... discovered in farmland soil bacteria within long stretches of perfect nucleotide identity with pathogenic proteobacteria....

Antibiotics promote aggregation within aquatic bacterial communities

Directory of Open Access Journals (Sweden)

Gianluca eCorno

2014-07-01

Full Text Available The release of antibiotics (AB into the environment poses several threats for human health due to potential development of ABresistant natural bacteria. Even though the use of low-dose antibiotics has been promoted in health care and farming, significant amounts of AB are observed in aquatic environments. Knowledge on the impact of AB on natural bacterial communities is missing both in terms of spread and evolution of resistance mechanisms, and of modifications of community composition and productivity. New approaches are required to study the response of microbial communities rather than individual resistance genes. In this study a chemostat-based experiment with 4 coexisting bacterial strains has been performed to mimicking the response of a freshwater bacterial community to the presence of antibiotics in low and high doses. Bacterial abundance rapidly decreased by 75% in the presence of AB, independently of their concentration, and remained constant until the end of the experiment. The bacterial community was mainly dominated by Aeromonas hydrophila and Brevundimonas intermedia while the other two strains, Micrococcus luteus and Rhodococcus sp. never exceed 10%. Interestingly, the bacterial strains, which were isolated at the end of the experiment, were not AB-resistant, while reassembled communities composed of the 4 strains, isolated from treatments under AB stress, significantly raised their performance (growth rate, abundance in the presence of AB compared to the communities reassembled with strains isolated from the treatment without AB. By investigating the phenotypic adaptations of the communities subjected to the different treatments, we found that the presence of AB significantly increased co-aggregation by 5-6 fold.These results represent the first observation of co-aggregation as a successful strategy of AB resistance based on phenotype in aquatic bacterial communities, and can represent a fundamental step in the understanding of

Old and New Glycopeptide Antibiotics: Action and Resistance

Directory of Open Access Journals (Sweden)

Elisa Binda

2014-11-01

Full Text Available Glycopeptides are considered antibiotics of last resort for the treatment of life-threatening infections caused by relevant Gram-positive human pathogens, such as Staphylococcus aureus, Enterococcus spp. and Clostridium difficile. The emergence of glycopeptide-resistant clinical isolates, first among enterococci and then in staphylococci, has prompted research for second generation glycopeptides and a flurry of activity aimed at understanding resistance mechanisms and their evolution. Glycopeptides are glycosylated non-ribosomal peptides produced by a diverse group of soil actinomycetes. They target Gram-positive bacteria by binding to the acyl-D-alanyl-D-alanine (D-Ala-D-Ala terminus of the growing peptidoglycan on the outer surface of the cytoplasmatic membrane. Glycopeptide-resistant organisms avoid such a fate by replacing the D-Ala-D-Ala terminus with D-alanyl-D-lactate (D-Ala-D-Lac or D-alanyl-D-serine (D-Ala-D-Ser, thus markedly reducing antibiotic affinity for the cellular target. Resistance has manifested itself in enterococci and staphylococci largely through the expression of genes (named van encoding proteins that reprogram cell wall biosynthesis and, thus, evade the action of the antibiotic. These resistance mechanisms were most likely co-opted from the glycopeptide producing actinomycetes, which use them to avoid suicide during antibiotic production, rather than being orchestrated by pathogen bacteria upon continued treatment. van-like gene clusters, similar to those described in enterococci, were in fact identified in many glycopeptide-producing actinomycetes, such as Actinoplanes teichomyceticus, which produces teicoplanin, and Streptomyces toyocaensis, which produces the A47934 glycopeptide. In this paper, we describe the natural and semi-synthetic glycopeptide antibiotics currently used as last resort drugs for Gram-positive infections and compare the van gene-based strategies of glycopeptide resistance among the pathogens and

Antimicrobial activity of Manuka honey against antibiotic-resistant strains of the cell wall-free bacteria Ureaplasma parvum and Ureaplasma urealyticum.

Science.gov (United States)

Hillitt, K L; Jenkins, R E; Spiller, O B; Beeton, M L

2017-03-01

The susceptibility of the cell wall-free bacterial pathogens Ureaplasma spp. to Manuka honey was examined. The minimum inhibitory concentration (MIC) of Manuka honey for four Ureaplasma urealyticum and four Ureaplasma parvum isolates was determined. Sensitivity to honey was also compared to clinical isolates with resistance to tetracycline, macrolide and fluoroquinolone antibiotics. Finally step-wise resistance training was utilized in an attempt to induce increased tolerance to honey. The MIC was dependent on the initial bacterial load with 7·5 and 18·0% w/v honey required to inhibit U. urealyticum at 1 and 10 6 colour changing units (CCU), respectively, and 4·8 and 15·3% w/v required to inhibit U. parvum at 1 and 10 6  CCU respectively. MIC values were consistently lower for U. parvum compared with U. urealyticum. Antimicrobial activity was seen against tetracycline-resistant, erythromycin-resistant and ciprofloxacin-resistant isolates at 10 5  CCU. No resistance to honey was observed with 50 consecutive challenges at increasing concentrations of honey. This is the first report of the antimicrobial activity of Manuka honey against a cell wall-free bacterial pathogen. The antimicrobial activity was retained against antibiotic-resistant strains and it was not possible to generate resistant mutants. Manuka honey is known to have a broad spectrum of antimicrobial activity, with the bacterial cell wall being suggested as a predominant site of action. This study has demonstrated that Manuka honey has activity against Ureaplasma spp., a genus of cell wall-free bacteria which are intrinsically resistant to many available antibiotics making treatment inherently difficult. This is the first report of the antimicrobial activity of Manuka honey against a bacterial pathogen, in the absence of a cell well and opens scope for the use of components of Manuka honey as a therapeutic among Ureaplasma infections. © 2016 The Society for Applied Microbiology.

[Spontaneous bacterial peritonitis].

Science.gov (United States)

Velkey, Bálint; Vitális, Eszter; Vitális, Zsuzsanna

2017-01-01

Spontaneous bacterial peritonitis occurs most commonly in cirrhotic patients with ascites. Pathogens get into the circulation by intestinal translocation and colonize in peritoneal fluid. Diagnosis of spontaneous bacterial peritonitis is based on elevated polymorphonuclear leukocyte count in the ascites (>0,25 G/L). Ascites culture is often negative but aids to get information about antibiotic sensitivity in positive cases. Treatment in stable patient can be intravenous then orally administrated ciprofloxacin or amoxicillin/clavulanic acid, while in severe cases intravenous III. generation cephalosporin. Nosocomial spontaneous bacterial peritonitis often caused by Gram-positive bacteria and multi-resistant pathogens can also be expected thus carbapenem should be the choice of the empiric treatment. Antibiotic prophylaxis should be considered. Norfloxacin is used most commonly, but changes are expected due to increase in quinolone resistance. As a primary prophylaxis, a short-term antibiotic treatment is recommended after gastrointestinal bleeding for 5 days, while long-term prophylaxis is for patients with low ascites protein, and advanced disease (400 mg/day). Secondary prophylaxis is recommended for all patients recovered from spontaneous bacterial peritonitis. Due to increasing antibiotic use of antibiotics prophylaxis is debated to some degree. Orv. Hetil., 2017, 158(2), 50-57.

Antimicrobial properties of black grape (Vitis vinifera L.) peel extracts against antibiotic-resistant pathogenic bacteria and toxin producing molds.

Science.gov (United States)

Yadav, Devbrat; Kumar, Arvind; Kumar, Pramod; Mishra, Diwaker

2015-01-01

Black grape peel possesses a substantial amount of polyphenolic antimicrobial compounds that can be used for controlling the growth of pathogenic microorganisms. The purpose of this study was to assess antibacterial and antifungal activity of black grape peel extracts against antibiotic-resistant pathogenic bacteria and toxin producing molds, respectively. Peel of grape was subjected to polyphenolic extraction using different solvents viz., water, ethanol, acetone, and methanol. Antibiotic-resistant strains of Staphylococcus aureus, Enterococcus faecalis, Enterobacter aerogenes, Salmonella typhimurium, and Escherichia coli were screened for the antibacterial activity of different grape extracts. Antibacterial activity was analyzed using agar well diffusion method. Penicillium chrysogenum, Penicillium expansum, Aspergillus niger and Aspergillus versicolor were screened for the antifungal activity. Antifungal activity was determined by counting nongerminated spores in the presence of peel extracts. As compared to other solvent extracts, methanol extracts possessed high antibacterial and antifungal activity. S. typhimurium and E. coli showed complete resistance against antibacterial action at screened concentrations of grape peel extracts. Maximum zone of inhibition was found in case of S. aureus, i.e., 22 mm followed by E. faecalis and E. aerogenes, i.e., 18 and 21 mm, respectively, at 1080 mg tannic acid equivalent (TAE)/ml. The maximum and minimum percent of growth inhibition was shown by P. expansum and A. niger as 73% and 15% at 1080 TAE/ml concentration of grape peel extract, respectively. Except S. typhimurium and E. coli, growth of all bacterial and mold species were found to be significantly (P < 0.05) inhibited by all the solvent extracts.

Impact of restricted amoxicillin/clavulanic acid use on Escherichia coli resistance--antibiotic DU90% profiles with bacterial resistance rates: a visual presentation.

Science.gov (United States)

Mimica Matanovic, Suzana; Bergman, Ulf; Vukovic, Dubravka; Wettermark, Björn; Vlahovic-Palcevski, Vera

2010-10-01

High use of amoxicillin/clavulanic acid (AMC) at the University Hospital Osijek (Croatia) contributed to high rates of resistance in Enterobacteriaceae, in particular Escherichia coli (50%). Thus, in order to decrease bacterial resistance, AMC use was restricted. We present results of the restriction on resistance amongst antibiotics accounting for 90% of antibiotic use [drug utilisation 90% (DU90%)]. Data were analysed on antibiotic use and microbiological susceptibility of E. coli during two 9-month periods, before and after the restriction of AMC use. Drug use was presented as numbers of defined daily doses (DDDs) and DDDs/100 bed-days. Resistance of E. coli to antibiotics was presented as percentages of isolated strains in the DU90% segment. Use of AMC was 16 DDDs/100 bed-days or 30% of all antibiotics before the intervention. Use of AMC fell to 2 DDDs/100 bed-days or 4% after the intervention, and resistance of E. coli fell from 37% to 11%. In conclusion, restricted use of AMC resulted in a significant decrease of E. coli resistance. DU90% resistance profiles are simple and useful tools in highlighting problems in antibiotic use and resistance but may also be useful in long-term follow-up of antibiotic policy. Copyright 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Relationship between lactobacilli and opportunistic bacterial pathogens associated with vaginitis.

Science.gov (United States)

Razzak, Mohammad Sabri A; Al-Charrakh, Alaa H; Al-Greitty, Bara Hamid

2011-04-01

Vaginitis, is an infectious inflammation of the vaginal mucosa, which sometimes involves the vulva. The balance of the vaginal flora is maintained by the Lactobacilli and its protective and probiotic role in treating and preventing vaginal infection by producing antagonizing compounds which are regarded as safe for humans. The aim of this study was to evaluate the protective role of Lactobacilli against common bacterial opportunistic pathogens in vaginitis and study the effects of some antibiotics on Lactobacilli isolates. In this study (110) vaginal swabs were obtained from women suffering from vaginitis who admitted to Babylon Hospital of Maternity and Paediatrics in Babylon province, Iraq. The study involved the role of intrauterine device among married women with vaginitis and also involved isolation of opportunistic bacterial isolates among pregnant and non pregnant women. This study also involved studying probiotic role of Lactobacilli by production of some defense factors like hydrogen peroxide, bacteriocin, and lactic acid. Results revealed that a total of 130 bacterial isolates were obtained. Intrauterine device was a predisposing factor for vaginitis. The most common opportunistic bacterial isolates were Staphylococcus aureus, Escherichia coli, Streptococcus agalactiae, and Klebsiella pneumoniae. All Lactobacilli were hydrogen peroxide producers while some isolates were bacteriocin producers that inhibited some of opportunistic pathogens (S. aureus, E. coli). Lactobacilli were sensitive to erythromycin while 93.3% of them were resistant to ciprofloxacin and (40%, 53.3%) of them were resistant to amoxicillin and gentamycin respectively. Results revealed that there was an inverse relationship between Lactobacilli presence and organisms causing vaginitis. This may be attributed to the production of defense factors by Lactobacilli. The types of antibiotics used to treat vaginitis must be very selective in order not to kill the beneficial bacteria

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.

Antagonistic Activities of Purple Non-sulfur Bacterial Extracts Against Antibiotic Resistant Vibrio sp.

Directory of Open Access Journals (Sweden)

Chandrasekaran, R.

2011-01-01

Full Text Available Solvent extracts of native purple non-sulfur bacterial (PNSB isolates from the effluents of brackish shrimp culture ponds, near Nagapattinam coast (South India were evaluated for antibacterial activity by the disc diffusion method. Best results were shown by the chloroform extracts against oxytetracycline resistant Vibrio harveyi and Vibrio fischerii. Among the purple non-sulfur bacterial isolates, Rhodobacter sphaeroides, showed maximum antagonistic activity. The findings suggest that the antagonistic extracts from Rba. sphaeroides could be used as an effective antibiotic in controlling Vibrio spp., in aquaculture systems.

Occurrence and antibacterial susceptibility pattern of bacterial pathogens isolated from diarrheal patients in Pakistan

Directory of Open Access Journals (Sweden)

Muhammad H. Rasool

2016-03-01

Full Text Available Objective: To determine the occurrence of bacterial pathogens responsible for diarrhea and to engender information regarding the effectiveness of commonly used antibiotic against diarrhea. Methods: This cross-sectional study was conducted between April and July 2014. Samples were collected from the Divisional Headquarter and Allied Hospital, Faisalabad, Pakistan. The differential and selective media were used to isolate bacterial pathogens, which were identified through cultural characteristics, microscopy, and biochemical tests. Disc diffusion assay was carried out using Muller Hinton agar medium, and minimum inhibitory concentration was determined using broth dilution method against isolated pathogens. Results: One hundred and forty-one (100% samples were positive for some bacteria. Frequency of occurrence was Bacillus cereus (B. cereus (66%, Escherichia coli (E. coli (48.5%, Salmonella typhi (S. Typhi (27.7%, Pseudomonas aeruginosa (P. aeruginosa (8.5%, and Staphylococcus aureus (S. aureus (4.3%. Single pathogen was detected in 20 (14.2% samples whereas combinations were found in 121 (85.8% samples. Bacillus cereus and E. coli were the most frequently detected pathogens followed by the S. Typhi, P. aeruginosa, and Staph. aureus. The percentage occurrence of isolated pathogens was 31% in B. cereus, 31% in E. coli, 18% in S. Typhi, 5% in P. aeruginosa, and 3% in Staph. aureus. Conclusion: Pseudomonas aeruginosa showed resistance against Amoxicillin and Cefotaxime, whereas S. aureus was found resistant against Cefotaxime. Statistical analysis using one way Analysis of Variance revealed that Ofloxacin and Gentamicin had significant (p<0.05 differences against all isolates as compared with other antibiotics used in this study.

Occurrence and antibacterial susceptibility pattern of bacterial pathogens isolated from diarrheal patients in Pakistan.

Science.gov (United States)

Rasool, Muhammad H; Siddique, Abu B; Saqalein, Muhammad; Asghar, Muhammad J; Zahoor, Muhammad A; Aslam, Bilal; Shafiq, Humerah B; Nisar, Muhammad A

2016-03-01

To determine the occurrence of bacterial pathogens responsible for diarrhea and to engender information regarding the effectiveness of commonly used antibiotic against diarrhea. This cross-sectional study was conducted between April and July 2014. Samples were collected from the Divisional Headquarter and Allied Hospital, Faisalabad, Pakistan. The differential and selective media were used to isolate bacterial pathogens, which were identified through cultural characteristics, microscopy, and biochemical tests. Disc diffusion assay was carried out using Muller Hinton agar medium, and minimum inhibitory concentration was determined using broth dilution method against isolated pathogens. One hundred and forty-one (100%) samples were positive for some bacteria. Frequency of occurrence was Bacillus cereus (B. cereus) (66%), Escherichia coli (E.coli) (48.5%), Salmonella typhi (S. Typhi) (27.7%), Pseudomonas aeruginosa (P. aeruginosa) (8.5%), and Staphylococcus aureus (S. aureus) (4.3%). Single pathogen was detected in 20 (14.2%) samples whereas combinations were found in 121 (85.8%) samples. Bacillus cereus and E.coli were the most frequently detected pathogens followed by the S. Typhi, P. aeruginosa, and Staph. aureus. The percentage occurrence of isolated pathogens was 31% in B. cereus, 31% in E. coli, 18% in S. Typhi, 5% in P. aeruginosa, and 3% in Staph. aureus. Pseudomonas aeruginosa showed resistance against Amoxicillin and Cefotaxime, whereas S. aureus was found resistant against Cefotaxime. Statistical analysis using one way Analysis of Variance revealed that Ofloxacin and Gentamicin had significant (p less than 0.05) differences against all isolates as compared with other antibiotics used in this study.

Role of Old Antibiotics in the Era of Antibiotic Resistance. Highlighted Nitrofurantoin for the Treatment of Lower Urinary Tract Infections

Directory of Open Access Journals (Sweden)

Maria Jose Munoz-Davila

2014-02-01

Full Text Available Bacterial infections caused by antibiotic-resistant isolates have become a major health problem in recent years, since they are very difficult to treat, leading to an increase in morbidity and mortality. Nitrofurantoin is a broad-spectrum bactericidal antibiotic that, through a complex mode of action which is not completely understood, affects both Gram-negative and Gram-positive bacteria. Nitrofurantoin has been used successfully for a long time for the prophylaxis and treatment of acute lower urinary tract infections in adults, children and pregnant women, but the increased emergence of antibiotic resistance has made nitrofurantoin a suitable candidate for the treatment of infections caused by multidrug-resistant pathogens. Here, we review the mechanism of action, antimicrobial spectrum, pharmacology and safety profile of nitrofurantoin. We also investigate the therapeutic use of nitrofurantoin, including recent data which highlight its role in the management of community urinary tract infection, especially in cases of multidrug-resistant isolates, in which oral active antimicrobials are limited resources nowadays.

Inhibition of growth of highly resistant bacterial and fungal pathogens by a natural product.

Science.gov (United States)

Hafidh, Rand R; Abdulamir, Ahmed S; Vern, Law Se; Abu Bakar, Fatimah; Abas, Faridah; Jahanshiri, Fatemeh; Sekawi, Zamberi

2011-01-01

The continuous escalation of resistant bacteria against a wide range of antibiotics necessitates discovering novel unconventional sources of antibiotics. B. oleracea L (red cabbage) is health-promoting food with proven anticancer and anti-inflammatory activities. However, it has not been researched adequately for its antimicrobial activity on potential resistant pathogens. The methanol crude extract of B. oleracea L. was investigated for a possible anti-microbial activity. The screening method was conducted using disc diffusion assay against 22 pathogenic bacteria and fungi. It was followed by evaluation of the minimum inhibitory concentration (MIC). Moreover, the antibacterial and the antifungal activities were confirmed using the minimum bactericidal concentration (MBC) and the minimum fungicidal concentration (MFC), respectively. Remarkable, antibacterial activity was evident particularly against highly infectious microorganisms such as Methicillin-resistant Staphylococcus aureus, Escherichia coli O157:H7, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Salmonella enterica serovar Typhimurium as well as against human fungal pathogens, Trichophyton rubrum and Aspergillus terreus. Red cabbage is a rich source of phenolic compounds, anthocyanins being the most abundant class, which might explain its potent antimicrobial action. This extract is potentially novel for future antimicrobials, inexpensive, and readily available at a large scale for pharmaceutical companies for further investigation and processing.

A locked nucleic acid (LNA-based real-time PCR assay for the rapid detection of multiple bacterial antibiotic resistance genes directly from positive blood culture.

Directory of Open Access Journals (Sweden)

Lingxiang Zhu

Full Text Available Bacterial strains resistant to various antibiotic drugs are frequently encountered in clinical infections, and the rapid identification of drug-resistant strains is highly essential for clinical treatment. We developed a locked nucleic acid (LNA-based quantitative real-time PCR (LNA-qPCR method for the rapid detection of 13 antibiotic resistance genes and successfully used it to distinguish drug-resistant bacterial strains from positive blood culture samples. A sequence-specific primer-probe set was designed, and the specificity of the assays was assessed using 27 ATCC bacterial strains and 77 negative blood culture samples. No cross-reaction was identified among bacterial strains and in negative samples, indicating 100% specificity. The sensitivity of the assays was determined by spiking each bacterial strain into negative blood samples, and the detection limit was 1-10 colony forming units (CFU per reaction. The LNA-qPCR assays were first applied to 72 clinical bacterial isolates for the identification of known drug resistance genes, and the results were verified by the direct sequencing of PCR products. Finally, the LNA-qPCR assays were used for the detection in 47 positive blood culture samples, 19 of which (40.4% were positive for antibiotic resistance genes, showing 91.5% consistency with phenotypic susceptibility results. In conclusion, LNA-qPCR is a reliable method for the rapid detection of bacterial antibiotic resistance genes and can be used as a supplement to phenotypic susceptibility testing for the early detection of antimicrobial resistance to allow the selection of appropriate antimicrobial treatment and to prevent the spread of resistant isolates.

Newly approved antibiotics and antibiotics reserved for resistant infections: Implications for emergency medicine.

Science.gov (United States)

Mazer-Amirshahi, Maryann; Pourmand, Ali; May, Larissa

2017-01-01

Millions of patients are evaluated every year in the emergency department (ED) for bacterial infections. Emergency physicians often diagnose and prescribe initial antibiotic therapy for a variety of bacterial infections, ranging from simple urinary tract infections to severe sepsis. In life-threatening infections, inappropriate choice of initial antibiotic has been shown to increase morbidity and mortality. As such, initiation of appropriate antibiotic therapy on the part of the emergency physician is critical. Increasing rates of antibiotic resistance, drug allergies, and antibiotic shortages further complicates the choice of antibiotics. Patients may have a history of prior resistant infections or culture data indicating that common first-line antibiotics used in the ED may be ineffective. In recent years, there have been several new antibiotic approvals as well as renewed interest in second and third line antibiotics because of the aforementioned concerns. In addition, several newly approved antibiotics have the advantage of being administered once weekly or even as a single infusion, which has the potential to decrease hospitalizations and healthcare costs. This article reviews newly approved antibiotics and antibiotics used to treat resistant infections with a focus on implications for emergency medicine. Copyright © 2016 Elsevier Inc. All rights reserved.

Antibiotic-Resistant Pathogenic Escherichia Coli Isolated from Rooftop Rainwater-Harvesting Tanks in the Eastern Cape, South Africa

Directory of Open Access Journals (Sweden)

Mokaba Shirley Malema

2018-05-01

Full Text Available Although many developing countries use harvested rainwater (HRW for drinking and other household purposes, its quality is seldom monitored. Continuous assessment of the microbial quality of HRW would ensure the safety of users of such water. The current study investigated the prevalence of pathogenic Escherichia coli strains and their antimicrobial resistance patterns in HRW tanks in the Eastern Cape, South Africa. Rainwater samples were collected weekly between June and September 2016 from 11 tanks in various areas of the province. Enumeration of E. coli was performed using the Colilert®18/Quanti-Tray® 2000 method. E. coli isolates were obtained and screened for their virulence potentials using polymerase chain reaction (PCR, and subsequently tested for antibiotic resistance using the disc-diffusion method against 11 antibiotics. The pathotype most detected was the neonatal meningitis E. coli (NMEC (ibeA 28% while pathotype enteroaggregative E. coli (EAEC was not detected. The highest resistance of the E. coli isolates was observed against Cephalothin (76%. All tested pathotypes were susceptible to Gentamicin, and 52% demonstrated multiple-antibiotic resistance (MAR. The results of the current study are of public health concern since the use of untreated harvested rainwater for potable purposes may pose a risk of transmission of pathogenic and antimicrobial-resistant E. coli.

Antibiotic-Resistant Pathogenic Escherichia Coli Isolated from Rooftop Rainwater-Harvesting Tanks in the Eastern Cape, South Africa.

Science.gov (United States)

Malema, Mokaba Shirley; Abia, Akebe Luther King; Tandlich, Roman; Zuma, Bonga; Mwenge Kahinda, Jean-Marc; Ubomba-Jaswa, Eunice

2018-05-01

Although many developing countries use harvested rainwater (HRW) for drinking and other household purposes, its quality is seldom monitored. Continuous assessment of the microbial quality of HRW would ensure the safety of users of such water. The current study investigated the prevalence of pathogenic Escherichia coli strains and their antimicrobial resistance patterns in HRW tanks in the Eastern Cape, South Africa. Rainwater samples were collected weekly between June and September 2016 from 11 tanks in various areas of the province. Enumeration of E. coli was performed using the Colilert ® 18/Quanti-Tray ® 2000 method. E. coli isolates were obtained and screened for their virulence potentials using polymerase chain reaction (PCR), and subsequently tested for antibiotic resistance using the disc-diffusion method against 11 antibiotics. The pathotype most detected was the neonatal meningitis E. coli (NMEC) ( ibeA 28%) while pathotype enteroaggregative E. coli (EAEC) was not detected. The highest resistance of the E. coli isolates was observed against Cephalothin (76%). All tested pathotypes were susceptible to Gentamicin, and 52% demonstrated multiple-antibiotic resistance (MAR). The results of the current study are of public health concern since the use of untreated harvested rainwater for potable purposes may pose a risk of transmission of pathogenic and antimicrobial-resistant E. coli.

Bacterial resistance to antibiotics in acne vulgaris: An in vitro study

Directory of Open Access Journals (Sweden)

Hassanzadeh Parvin

2008-01-01

Full Text Available Background: Acne vulgaris is one of the most common skin disorders in youth especially during the puberty. Objective: This in vitro study was performed to determine the antibiotic resistance and sensitivity in acne vulgaris. Materials and Methods: Samples were collected from normal skin and nodulocystic and pustular skin lesions of one hundred youngsters (64 girls, 36 boys among college students in the age range of 18-24 years old. The specimens were cultured individually on blood agar and Muller-Hinton media. The cultures were then incubated under both aerobic and anaerobic conditions for 2 to 7 days. Bacteria were identified and their resistance to common antibiotics was evaluated according to the standard procedures. Results: In aerobic culture of pustular and nodulocystic skin lesions, Staphylococcus aureus was present in 41% of subjects, Staphylococcus epidermidis in 53% and Micrococcus spp in 45% of subjucts. In anaerobic bacterial culture of pustular and nodulocystic skin lesions, Staphylococcus aureus was present in 39%, Propionibacterium acne in 33% and Staphylococcus epidermidis in 21% of subjects. The results of present study revealed that clindamycin and erythromycin were the least effective antibiotics for Propionibacterium acne while tetracycline was the least effective for Staphylococcus aureus in vitro . A synergic effect of benzoyl peroxide, erythromycin or clindamycin was noticed. Rifampin was the most effective antibiotic in vitro . Conclusion: Our results showed that rifampin was the most sensitive antibiotic in vitro for acne vulgaris. To achieve a better treatment, a combination of rifampin with other antibiotics may be more efficient. We suggest in vivo studies for better evaluation and treatment of acne patients with rifampin.

Copper Resistance of the Emerging Pathogen Acinetobacter baumannii

Science.gov (United States)

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

2016-01-01

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

Copper Resistance of the Emerging Pathogen Acinetobacter baumannii.

Science.gov (United States)

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

2016-10-15

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

Self-resistance in Streptomyces, with Special Reference to β-Lactam Antibiotics.

Science.gov (United States)

Ogawara, Hiroshi

2016-05-10

Antibiotic resistance is one of the most serious public health problems. Among bacterial resistance, β-lactam antibiotic resistance is the most prevailing and threatening area. Antibiotic resistance is thought to originate in antibiotic-producing bacteria such as Streptomyces. In this review, β-lactamases and penicillin-binding proteins (PBPs) in Streptomyces are explored mainly by phylogenetic analyses from the viewpoint of self-resistance. Although PBPs are more important than β-lactamases in self-resistance, phylogenetically diverse β-lactamases exist in Streptomyces. While class A β-lactamases are mostly detected in their enzyme activity, over two to five times more classes B and C β-lactamase genes are identified at the whole genomic level. These genes can subsequently be transferred to pathogenic bacteria. As for PBPs, two pairs of low affinity PBPs protect Streptomyces from the attack of self-producing and other environmental β-lactam antibiotics. PBPs with PASTA domains are detectable only in class A PBPs in Actinobacteria with the exception of Streptomyces. None of the Streptomyces has PBPs with PASTA domains. However, one of class B PBPs without PASTA domain and a serine/threonine protein kinase with four PASTA domains are located in adjacent positions in most Streptomyces. These class B type PBPs are involved in the spore wall synthesizing complex and probably in self-resistance. Lastly, this paper emphasizes that the resistance mechanisms in Streptomyces are very hard to deal with, despite great efforts in finding new antibiotics.

ABC-F Proteins Mediate Antibiotic Resistance through Ribosomal Protection.

Science.gov (United States)

Sharkey, Liam K R; Edwards, Thomas A; O'Neill, Alex J

2016-03-22

Members of the ABC-F subfamily of ATP-binding cassette proteins mediate resistance to a broad array of clinically important antibiotic classes that target the ribosome of Gram-positive pathogens. The mechanism by which these proteins act has been a subject of long-standing controversy, with two competing hypotheses each having gained considerable support: antibiotic efflux versus ribosomal protection. Here, we report on studies employing a combination of bacteriological and biochemical techniques to unravel the mechanism of resistance of these proteins, and provide several lines of evidence that together offer clear support to the ribosomal protection hypothesis. Of particular note, we show that addition of purified ABC-F proteins to anin vitrotranslation assay prompts dose-dependent rescue of translation, and demonstrate that such proteins are capable of displacing antibiotic from the ribosomein vitro To our knowledge, these experiments constitute the first direct evidence that ABC-F proteins mediate antibiotic resistance through ribosomal protection.IMPORTANCEAntimicrobial resistance ranks among the greatest threats currently facing human health. Elucidation of the mechanisms by which microorganisms resist the effect of antibiotics is central to understanding the biology of this phenomenon and has the potential to inform the development of new drugs capable of blocking or circumventing resistance. Members of the ABC-F family, which includelsa(A),msr(A),optr(A), andvga(A), collectively yield resistance to a broader range of clinically significant antibiotic classes than any other family of resistance determinants, although their mechanism of action has been controversial since their discovery 25 years ago. Here we present the first direct evidence that proteins of the ABC-F family act to protect the bacterial ribosome from antibiotic-mediated inhibition. Copyright © 2016 Sharkey et al.

Environmental and Public Health Implications of Water Reuse: Antibiotics, Antibiotic Resistant Bacteria, and Antibiotic Resistance Genes

Science.gov (United States)

Hong, Pei-Ying; Al-Jassim, Nada; Ansari, Mohd Ikram; Mackie, Roderick I.

2013-01-01

Water scarcity is a global problem, and is particularly acute in certain regions like Africa, the Middle East, as well as the western states of America. A breakdown on water usage revealed that 70% of freshwater supplies are used for agricultural irrigation. The use of reclaimed water as an alternative water source for agricultural irrigation would greatly alleviate the demand on freshwater sources. This paradigm shift is gaining momentum in several water scarce countries like Saudi Arabia. However, microbial problems associated with reclaimed water may hinder the use of reclaimed water for agricultural irrigation. Of particular concern is that the occurrence of antibiotic residues in the reclaimed water can select for antibiotic resistance genes among the microbial community. Antibiotic resistance genes can be associated with mobile genetic elements, which in turn allow a promiscuous transfer of resistance traits from one bacterium to another. Together with the pathogens that are present in the reclaimed water, antibiotic resistant bacteria can potentially exchange mobile genetic elements to create the “perfect microbial storm”. Given the significance of this issue, a deeper understanding of the occurrence of antibiotics in reclaimed water, and their potential influence on the selection of resistant microorganisms would be essential. In this review paper, we collated literature over the past two decades to determine the occurrence of antibiotics in municipal wastewater and livestock manure. We then discuss how these antibiotic resistant bacteria may impose a potential microbial risk to the environment and public health, and the knowledge gaps that would have to be addressed in future studies. Overall, the collation of the literature in wastewater treatment and agriculture serves to frame and identify potential concerns with respect to antibiotics, antibiotic resistant bacteria, and antibiotic resistance genes in reclaimed water. PMID:27029309

Environmental and Public Health Implications of Water Reuse: Antibiotics, Antibiotic Resistant Bacteria, and Antibiotic Resistance Genes

Directory of Open Access Journals (Sweden)

Roderick I. Mackie

2013-07-01

Full Text Available Water scarcity is a global problem, and is particularly acute in certain regions like Africa, the Middle East, as well as the western states of America. A breakdown on water usage revealed that 70% of freshwater supplies are used for agricultural irrigation. The use of reclaimed water as an alternative water source for agricultural irrigation would greatly alleviate the demand on freshwater sources. This paradigm shift is gaining momentum in several water scarce countries like Saudi Arabia. However, microbial problems associated with reclaimed water may hinder the use of reclaimed water for agricultural irrigation. Of particular concern is that the occurrence of antibiotic residues in the reclaimed water can select for antibiotic resistance genes among the microbial community. Antibiotic resistance genes can be associated with mobile genetic elements, which in turn allow a promiscuous transfer of resistance traits from one bacterium to another. Together with the pathogens that are present in the reclaimed water, antibiotic resistant bacteria can potentially exchange mobile genetic elements to create the “perfect microbial storm”. Given the significance of this issue, a deeper understanding of the occurrence of antibiotics in reclaimed water, and their potential influence on the selection of resistant microorganisms would be essential. In this review paper, we collated literature over the past two decades to determine the occurrence of antibiotics in municipal wastewater and livestock manure. We then discuss how these antibiotic resistant bacteria may impose a potential microbial risk to the environment and public health, and the knowledge gaps that would have to be addressed in future studies. Overall, the collation of the literature in wastewater treatment and agriculture serves to frame and identify potential concerns with respect to antibiotics, antibiotic resistant bacteria, and antibiotic resistance genes in reclaimed water.

Environmental and Public Health Implications of Water Reuse: Antibiotics, Antibiotic Resistant Bacteria, and Antibiotic Resistance Genes

KAUST Repository

Hong, Pei-Ying; Aljassim, Nada I.; Ansari, Mohd Ikram; Mackie, Roderick

2013-01-01

Water scarcity is a global problem, and is particularly acute in certain regions like Africa, the Middle East, as well as the western states of America. A breakdown on water usage revealed that 70% of freshwater supplies are used for agricultural irrigation. The use of reclaimed water as an alternative water source for agricultural irrigation would greatly alleviate the demand on freshwater sources. This paradigm shift is gaining momentum in several water scarce countries like Saudi Arabia. However, microbial problems associated with reclaimed water may hinder the use of reclaimed water for agricultural irrigation. Of particular concern is that the occurrence of antibiotic residues in the reclaimed water can select for antibiotic resistance genes among the microbial community. Antibiotic resistance genes can be associated with mobile genetic elements, which in turn allow a promiscuous transfer of resistance traits from one bacterium to another. Together with the pathogens that are present in the reclaimed water, antibiotic resistant bacteria can potentially exchange mobile genetic elements to create the “perfect microbial storm”. Given the significance of this issue, a deeper understanding of the occurrence of antibiotics in reclaimed water, and their potential influence on the selection of resistant microorganisms would be essential. In this review paper, we collated literature over the past two decades to determine the occurrence of antibiotics in municipal wastewater and livestock manure. We then discuss how these antibiotic resistant bacteria may impose a potential microbial risk to the environment and public health, and the knowledge gaps that would have to be addressed in future studies. Overall, the collation of the literature in wastewater treatment and agriculture serves to frame and identify potential concerns with respect to antibiotics, antibiotic resistant bacteria, and antibiotic resistance genes in reclaimed water.

Environmental and Public Health Implications of Water Reuse: Antibiotics, Antibiotic Resistant Bacteria, and Antibiotic Resistance Genes

KAUST Repository

Hong, Pei-Ying

2013-07-31

Water scarcity is a global problem, and is particularly acute in certain regions like Africa, the Middle East, as well as the western states of America. A breakdown on water usage revealed that 70% of freshwater supplies are used for agricultural irrigation. The use of reclaimed water as an alternative water source for agricultural irrigation would greatly alleviate the demand on freshwater sources. This paradigm shift is gaining momentum in several water scarce countries like Saudi Arabia. However, microbial problems associated with reclaimed water may hinder the use of reclaimed water for agricultural irrigation. Of particular concern is that the occurrence of antibiotic residues in the reclaimed water can select for antibiotic resistance genes among the microbial community. Antibiotic resistance genes can be associated with mobile genetic elements, which in turn allow a promiscuous transfer of resistance traits from one bacterium to another. Together with the pathogens that are present in the reclaimed water, antibiotic resistant bacteria can potentially exchange mobile genetic elements to create the “perfect microbial storm”. Given the significance of this issue, a deeper understanding of the occurrence of antibiotics in reclaimed water, and their potential influence on the selection of resistant microorganisms would be essential. In this review paper, we collated literature over the past two decades to determine the occurrence of antibiotics in municipal wastewater and livestock manure. We then discuss how these antibiotic resistant bacteria may impose a potential microbial risk to the environment and public health, and the knowledge gaps that would have to be addressed in future studies. Overall, the collation of the literature in wastewater treatment and agriculture serves to frame and identify potential concerns with respect to antibiotics, antibiotic resistant bacteria, and antibiotic resistance genes in reclaimed water.

Chemical composition and antibacterial activities of Illicium verum against antibiotic-resistant pathogens.

Science.gov (United States)

Yang, Jyh-Ferng; Yang, Cheng-Hong; Chang, Hsueh-Wei; Yang, Cheng-San; Wang, Shao-Ming; Hsieh, Ming-Che; Chuang, Li-Yeh

2010-10-01

In recent years, human pathogenic microorganisms have developed multiple drug resistance and caused serious nosocomial infections. In this study, we identified four new antimicrobial compounds from the Chinese herbal medicine Illicium verum and assessed their antibacterial efficacies. The supercritical CO₂ and ethanol extracts of Illicium verum showed substantial antibacterial activity against 67 clinical drug-resistant isolates, including 27 Acinetobacter baumannii, 20 Pseudomonas aeruginosa, and 20 methicillin-resistant Staphylococcus aureus. The diethyl ether (EE) fraction obtained from partition extraction and supercritical CO₂ extracts revealed an antibacterial activity with a minimum inhibitory concentration value of 0.15-0.70 mg/mL and 0.11 mg/mL, respectively. The EE fraction of I. verum showed synergetic effects with some commercial antibiotics. The antimicrobial mechanism was investigated with killing curves and scanning electron microscopy observation. The chemical components of the extracts were analyzed by spectrophotometry; (E)-anethole, anisyl acetone, anisyl alcohol, and anisyl aldehyde exhibited antibacterial activity against different clinical isolates. These extracts from I. verum can be further developed into antibiotic medicines due to their proven antibacterial activity.

Conjunctival bacterial flora and antibiotic resistance pattern in patients undergoing cataract surgery

International Nuclear Information System (INIS)

Ansari, M.R.; Modani, H.

2008-01-01

The purpose of this study was to evaluate the conjunctival bacterial flora and its antibiotic susceptibility pattern in eyes of patients undergoing cataract surgery. Conjunctival soap was obtained on the day of surgery before the application of topical anesthetic, antibiotic or povidone-iodine. Culture and antibiotic susceptibility tests were performed. The data was analysed with X/sup 2/ and T tests. Of the 170 patients 89 cases (52.4%) had positive cultures in the eyes. In 79 eyes (88.8%) found coagulase-negative Staphylococcus (CoNS). Eighty two cases (95.3%) of isolated Staphylococcus were susceptible to Amikacin, 86 (100%) sensitive to Ciprofloxacin and 42 (48.8%) sensitive to Ceftazidime. Average susceptibility and resistancy to antibiotics was 2.6 (+-1.8) antibiotics in women and 1.6(+-1.4) in men (P= 0.009). This study showed that the bacterium most frequently found in the conjunctival flora of the patients undergoing cataract surgery was CoNS. Isolates of this bacterium had low CoNS susceptibility rates to Caftazidime and Vancomycin and high susceptibility to Ciprofloxacin and Amikacin. (author)

Co-Selection of Resistance to Antibiotics, Biocides and Heavy Metals, and Its Relevance to Foodborne Pathogens

OpenAIRE

Wales, Andrew; Davies, RH

2015-01-01

Concerns have been raised in recent years regarding co-selection for antibiotic resistance among bacteria exposed to biocides used as disinfectants, antiseptics and preservatives, and to heavy metals (particularly copper and zinc) used as growth promoters and therapeutic agents for some livestock species. There is indeed experimental and observational evidence that exposure to these non-antibiotic antimicrobial agents can induce or select for bacterial adaptations that result in decreased sus...

Analysis of clinical isolates of Helicobacter pylori in Pakistan reveals high degrees of pathogenicity and high frequencies of antibiotic resistance.

Science.gov (United States)

Rasheed, Faisal; Campbell, Barry James; Alfizah, Hanafiah; Varro, Andrea; Zahra, Rabaab; Yamaoka, Yoshio; Pritchard, David Mark

2014-10-01

Antibiotic resistance in Helicobacter pylori contributes to failure in eradicating the infection and is most often due to point and missense mutations in a few key genes. The antibiotic susceptibility profiles of H. pylori isolates from 46 Pakistani patients were determined by Etest. Resistance and pathogenicity genes were amplified, and sequences were analyzed to determine the presence of mutations. A high percentage of isolates (73.9%) were resistant to metronidazole (MTZ), with considerable resistance to clarithromycin (CLR; 47.8%) and amoxicillin (AML; 54.3%) also observed. Relatively few isolates were resistant to tetracycline (TET; 4.3%) or to ciprofloxacin (CIP; 13%). However, most isolates (n = 43) exhibited resistance to one or more antibiotics. MTZ-resistant isolates contained missense mutations in oxygen-independent NADPH nitroreductase (RdxA; 8 mutations found) and NADH flavin oxidoreductase (FrxA; 4 mutations found). In the 23S rRNA gene, responsible for CLR resistance, a new point mutation (A2181G) and 4 previously reported mutations were identified. Pathogenicity genes cagA, dupA, and vacA s1a/m1 were detected frequently in isolates which were also found to be resistant to MTZ, CLR, and AML. A high percentage of CagA and VacA seropositivity was also observed in these patients. Phylogenetic analysis of partial sequences showed uniform distribution of the 3' region of cagA throughout the tree. We have identified H. pylori isolates in Pakistan which harbor pathogenicity genes and worrying antibiotic resistance profiles as a result of having acquired multiple point and missense mutations. H. pylori eradication regimens should therefore be reevaluated in this setting. © 2014 John Wiley & Sons Ltd.

The antibiotic resistome.

Science.gov (United States)

Wright, Gerard D

2010-08-01

Antibiotics are essential for the treatment of bacterial infections and are among our most important drugs. Resistance has emerged to all classes of antibiotics in clinical use. Antibiotic resistance has, proven inevitable and very often it emerges rapidly after the introduction of a drug into the clinic. There is, therefore, a great interest in understanding the origins, scope and evolution of antibiotic resistance. The review discusses the concept of the antibiotic resistome, which is the collection of all genes that directly or indirectly contribute to antibiotic resistance. The review seeks to assemble current knowledge of the resistome concept as a means of understanding the totality of resistance and not just resistance in pathogenic bacteria. The concept of the antibiotic resistome provides a framework for the study and understanding of how resistance emerges and evolves. Furthermore, the study of the resistome reveals strategies that can be applied in new antibiotic discoveries.

Epidemiological and antibiotic susceptibility profiles of infectious bacterial diarrhoea in Juba, South Sudan

Directory of Open Access Journals (Sweden)

Juma John Hassen Mogga

2015-11-01

Full Text Available Background: Diarrhoeal diseases have remained a major health problem in South Sudan where they accounted 45% prevalence in under five-year olds. Between 2006 and 2007, the country reported a morbidity of 8,337 cases and 176 deaths due to diarrhoeal outbreaks. Methodology: We investigated causative agents of diarrhoeal diseases and their antibiogram in persons presenting with diarrhoea to selected health facilities in Juba. Results: Bacterial agents were prevalent in 20(6.9% of the 286 patients with 5.7%(4/70 in under five-year olds alone. S. dysenteriae 50% (10/20 accounted for the majority of the identified pathogens followed S. flexneri 25% (5/20 and S. typh 25% (5/20. Antibiotic testing showed that S. flexneri (5/5 and S. typhi (5/5 were all 100% sensitive to ceftriaxone, and gentamicin while S. dysenteriae had varying sensitivity to ciprofloxacin (70%, nalidixic acid (90%, and ceftriaxone(100%. These pathogens had 100% resistance to amoxicillin, ampicillin, tetracycline and cotrimoxazole. No difference existed in isolation rates among different age groups, educational status, gender, water drank, use of chlorine, toilet use, exposure at home to diarrhoea patient, hand washing with soap and location of residence. However, diarrhoeagenic bacteria isolation was higher for participants with no source of income (OR=6.08, p<0.05. Conclusion: With emerging menace of resistance to commonly used antibiotics in South Sudan we recommend antibiotic resistance monitoring and regulation of antibiotic use.

How to measure the impacts of antibiotic resistance and antibiotic development on empiric therapy: new composite indices.

Science.gov (United States)

Hughes, Josie S; Hurford, Amy; Finley, Rita L; Patrick, David M; Wu, Jianhong; Morris, Andrew M

2016-12-16

We aimed to construct widely useable summary measures of the net impact of antibiotic resistance on empiric therapy. Summary measures are needed to communicate the importance of resistance, plan and evaluate interventions, and direct policy and investment. As an example, we retrospectively summarised the 2011 cumulative antibiogram from a Toronto academic intensive care unit. We developed two complementary indices to summarise the clinical impact of antibiotic resistance and drug availability on empiric therapy. The Empiric Coverage Index (ECI) measures susceptibility of common bacterial infections to available empiric antibiotics as a percentage. The Empiric Options Index (EOI) varies from 0 to 'the number of treatment options available', and measures the empiric value of the current stock of antibiotics as a depletable resource. The indices account for drug availability and the relative clinical importance of pathogens. We demonstrate meaning and use by examining the potential impact of new drugs and threatening bacterial strains. In our intensive care unit coverage of device-associated infections measured by the ECI remains high (98%), but 37-44% of treatment potential measured by the EOI has been lost. Without reserved drugs, the ECI is 86-88%. New cephalosporin/β-lactamase inhibitor combinations could increase the EOI, but no single drug can compensate for losses. Increasing methicillin-resistant Staphylococcus aureus (MRSA) prevalence would have little overall impact (ECI=98%, EOI=4.8-5.2) because many Gram-positives are already resistant to β-lactams. Aminoglycoside resistance, however, could have substantial clinical impact because they are among the few drugs that provide coverage of Gram-negative infections (ECI=97%, EOI=3.8-4.5). Our proposed indices summarise the local impact of antibiotic resistance on empiric coverage (ECI) and available empiric treatment options (EOI) using readily available data. Policymakers and drug developers can use the

Antibiotic activity and synergistic effect of antimicrobial peptide against pathogens from a patient with gallstones

International Nuclear Information System (INIS)

Park, Yoonkyung; Park, Soon Nang; Park, Seong-Cheol; Park, Joon Yong; Park, Yong Ha; Hahm, Joon Soo; Hahm, Kyung-Soo

2004-01-01

HP (2-20) is a peptide derived from the N-terminus of Helicobacter pylori ribosomal protein L1 that has been shown to have antimicrobial activity against various species of bacteria. When we tested the effects of HP (2-20), we found that this peptide displayed strong activity against pathogens from a patient with gallstones, but it did not have hemolytic activity against human erythrocytes. We also found that HP (2-20) had potent activity against cefazolin sodium-resistant bacterial cell lines, and that HP (2-20) and cefazolin sodium had synergistic effects against cell lines resistant to the latter. To investigate the mechanism of action of HP (2-20), we performed fluorescence activated flow cytometry using pathogens from the patient with gallstones. As determined by propidium iodide (PI) staining, pathogenic bacteria treated with HP (2-20) showed higher fluorescence intensity than untreated cells, similar to melittin-treated cells, and that HP (2-20) acted in an energy- and salt-dependent manner. Scanning electron microscopy showed that HP (2-20) caused significant morphological alterations in the cell surface of pathogens from the patient with gallstones. By determining their 16S rDNA sequences, we found that both the pathogens from the patient with gallstones and the cefazolin sodium-resistant cell lines showed 100% homology with sequences from Pseudomonas aeruginosa. Taken together, these results suggest that HP (2-20) has antibiotic activity and that it may be used as a lead drug for the treatment of acquired pathogens from patients with gallstones and antibiotic-resistant cell lines

The survey of bacterial etiology and their resistance to antibiotics of urinary tract infections in children of Birjand city

Directory of Open Access Journals (Sweden)

Azita Fesharakinia

2012-08-01

Full Text Available Background and Aim: Urinary tract infection is one of the most prevalent bacterial infections in childhood, which due to an inapproto determine the common bacteria and their antibiotic susceptibility in children with urinary tract infection.   Materials and Methods: This descriptive-analytical and prospective study was done in 2009-2010 on urine samples of all children under 13 years who had been referred to Emmam-Reza hospital laboratory in Birjand and had positive urine culture. Sex and age of children, the kind of isolated bacteria in urine culture, susceptibility and resistance of these bacteria to current antibiotics were studied.The obtained data was analyzed by means of SPSS using Fisher exact- test.   Results: 100 children (84 girls and 16 boys with positive urine culture were studied. The most common age of urinary tract infection was under two years. In all ages the rate of urinary tract infection in females was more than males. E.coli was the most common cause in both sexes. There was a significant relationship between kind of microorganism and age of infection. The most prevalent cause of urinary tract infection in all ages was E.coli (75% ,infection by Proteus was 11%, and other microorganism caused 14% of the cases. E.coli had the most susceptibility to ceftriaxone and ceftazidime and the most resistance to cephalexin and co-trimoxazol. Not taking the type of microorganism into consideration, the most sensitive antibiotics were ceftazidime, ceftriaxone, cefexim and nalidixic acid and the most resistance was against co-trimoxasol and cefalexin.   Conclusion: Regarding the results, it is recommended to use cefexime and nalidixic acid for outpatient treatment of urinary infection , and ceftazidime and ceftriaxon for inpatient treatment.Selecting of antibiotics for urinary infection therapy should be based on the local prevalence of pathogenic bacteria and antibiotic sensitivities rather than on a universal guideline.

A rapid two-step algorithm detects and identifies clinical macrolide and beta-lactam antibiotic resistance in clinical bacterial isolates.

Science.gov (United States)

Lu, Xuedong; Nie, Shuping; Xia, Chengjing; Huang, Lie; He, Ying; Wu, Runxiang; Zhang, Li

2014-07-01

Aiming to identify macrolide and beta-lactam resistance in clinical bacterial isolates rapidly and accurately, a two-step algorithm was developed based on detection of eight antibiotic resistance genes. Targeting at genes linked to bacterial macrolide (msrA, ermA, ermB, and ermC) and beta-lactam (blaTEM, blaSHV, blaCTX-M-1, blaCTX-M-9) antibiotic resistances, this method includes a multiplex real-time PCR, a melting temperature profile analysis as well as a liquid bead microarray assay. Liquid bead microarray assay is applied only when indistinguishable Tm profile is observed. The clinical validity of this method was assessed on clinical bacterial isolates. Among the total 580 isolates that were determined by our diagnostic method, 75% of them were identified by the multiplex real-time PCR with melting temperature analysis alone, while the remaining 25% required both multiplex real-time PCR with melting temperature analysis and liquid bead microarray assay for identification. Compared with the traditional phenotypic antibiotic susceptibility test, an overall agreement of 81.2% (kappa=0.614, 95% CI=0.550-0.679) was observed, with a sensitivity and specificity of 87.7% and 73% respectively. Besides, the average test turnaround time is 3.9h, which is much shorter in comparison with more than 24h for the traditional phenotypic tests. Having the advantages of the shorter operating time and comparable high sensitivity and specificity with the traditional phenotypic test, our two-step algorithm provides an efficient tool for rapid determination of macrolide and beta-lactam antibiotic resistances in clinical bacterial isolates. Copyright © 2014 Elsevier B.V. All rights reserved.

Distribution of triclosan-resistant genes in major pathogenic microorganisms revealed by metagenome and genome-wide analysis.

Directory of Open Access Journals (Sweden)

Raees Khan

presumed. Further, the excessive use of this biocide in natural environments may selectively enrich for not only TCS-resistant bacterial pathogens, but possibly for additional resistance to multiple antibiotics.

Distribution of triclosan-resistant genes in major pathogenic microorganisms revealed by metagenome and genome-wide analysis

Science.gov (United States)

Khan, Raees; Roy, Nazish; Choi, Kihyuck

2018-01-01

. Further, the excessive use of this biocide in natural environments may selectively enrich for not only TCS-resistant bacterial pathogens, but possibly for additional resistance to multiple antibiotics. PMID:29420585

Action and resistance mechanisms of antibiotics: A guide for clinicians

Directory of Open Access Journals (Sweden)

Garima Kapoor

2017-01-01

Full Text Available Infections account for a major cause of death throughout the developing world. This is mainly due to the emergence of newer infectious agents and more specifically due to the appearance of antimicrobial resistance. With time, the bacteria have become smarter and along with it, massive imprudent usage of antibiotics in clinical practice has resulted in resistance of bacteria to antimicrobial agents. The antimicrobial resistance is recognized as a major problem in the treatment of microbial infections. The biochemical resistance mechanisms used by bacteria include the following: antibiotic inactivation, target modification, altered permeability, and “bypass” of metabolic pathway. Determination of bacterial resistance to antibiotics of all classes (phenotypes and mutations that are responsible for bacterial resistance to antibiotics (genetic analysis are helpful. Better understanding of the mechanisms of antibiotic resistance will help clinicians regarding usage of antibiotics in different situations. This review discusses the mechanism of action and resistance development in commonly used antimicrobials.

Antibiotics and the resistant microbiome

DEFF Research Database (Denmark)

Sommer, Morten; Dantas, Gautam

2011-01-01

. Less appreciated are the concomitant changes in the human microbiome in response to these assaults and their contribution to clinical resistance problems. Studies have shown that pervasive changes to the human microbiota result from antibiotic treatment and that resistant strains can persist for years....... Additionally, culture-independent functional characterization of the resistance genes from the microbiome has demonstrated a close evolutionary relationship between resistance genes in the microbiome and in pathogens. Application of these techniques and novel cultivation methods are expected to significantly...... expand our understanding of the interplay between antibiotics and the microbiome....

Ribosomal Antibiotics: Contemporary Challenges

Directory of Open Access Journals (Sweden)

Tamar Auerbach-Nevo

2016-06-01

Full Text Available Most ribosomal antibiotics obstruct distinct ribosomal functions. In selected cases, in addition to paralyzing vital ribosomal tasks, some ribosomal antibiotics are involved in cellular regulation. Owing to the global rapid increase in the appearance of multi-drug resistance in pathogenic bacterial strains, and to the extremely slow progress in developing new antibiotics worldwide, it seems that, in addition to the traditional attempts at improving current antibiotics and the intensive screening for additional natural compounds, this field should undergo substantial conceptual revision. Here, we highlight several contemporary issues, including challenging the common preference of broad-range antibiotics; the marginal attention to alterations in the microbiome population resulting from antibiotics usage, and the insufficient awareness of ecological and environmental aspects of antibiotics usage. We also highlight recent advances in the identification of species-specific structural motifs that may be exploited for the design and the creation of novel, environmental friendly, degradable, antibiotic types, with a better distinction between pathogens and useful bacterial species in the microbiome. Thus, these studies are leading towards the design of “pathogen-specific antibiotics,” in contrast to the current preference of broad range antibiotics, partially because it requires significant efforts in speeding up the discovery of the unique species motifs as well as the clinical pathogen identification.

Prevalence of antibiotic resistance genes and bacterial community composition in a river influenced by a wastewater treatment plant.

Directory of Open Access Journals (Sweden)

Elisabet Marti

Full Text Available Antibiotic resistance represents a global health problem, requiring better understanding of the ecology of antibiotic resistance genes (ARGs, their selection and their spread in the environment. Antibiotics are constantly released to the environment through wastewater treatment plant (WWTP effluents. We investigated, therefore, the effect of these discharges on the prevalence of ARGs and bacterial community composition in biofilm and sediment samples of a receiving river. We used culture-independent approaches such as quantitative PCR to determine the prevalence of eleven ARGs and 16S rRNA gene-based pyrosequencing to examine the composition of bacterial communities. Concentration of antibiotics in WWTP influent and effluent were also determined. ARGs such as qnrS, bla TEM, bla CTX-M, bla SHV, erm(B, sul(I, sul(II, tet(O and tet(W were detected in all biofilm and sediment samples analyzed. Moreover, we observed a significant increase in the relative abundance of ARGs in biofilm samples collected downstream of the WWTP discharge. We also found significant differences with respect to community structure and composition between upstream and downstream samples. Therefore, our results indicate that WWTP discharges may contribute to the spread of ARGs into the environment and may also impact on the bacterial communities of the receiving river.

A consistent and predictable commercial broiler chicken bacterial microbiota in antibiotic-free production displays strong correlations with performance.

Science.gov (United States)

Johnson, Timothy J; Youmans, Bonnie P; Noll, Sally; Cardona, Carol; Evans, Nicholas P; Karnezos, T Peter; Ngunjiri, John M; Abundo, Michael C; Lee, Chang-Won

2018-04-06

Defining the baseline bacterial microbiome is critical towards understanding its relationship with health and disease. In broiler chickens, the core microbiome and its possible relationships with health and disease have been difficult to define due to high variability between birds and flocks. Presented are data from a large, comprehensive microbiota-based study in commercial broilers. The primary goals of this study included understanding what constitutes the core bacterial microbiota in the broiler gastrointestinal, respiratory, and barn environments; how these core players change across age, geography, and time; and which bacterial taxa correlate with enhanced bird performance in antibiotic-free flocks. Using 2,309 samples from 37 different commercial flocks within a vertically integrated broiler system, and metadata from these and an additional 512 flocks within that system, the baseline bacterial microbiota was defined using 16S rRNA gene sequencing. The effects of age, sample type, flock, and successive flock cycles were compared, and results indicate a consistent, predictable, age-dependent bacterial microbiota, irrespective of flock. The tracheal bacterial microbiota of broilers was comprehensively defined, and Lactobacillus was the dominant bacterial taxa in the trachea. Numerous bacterial taxa were identified which were strongly correlated with broiler chicken performance, across multiple tissues. While many positively correlated taxa were identified, negatively associated potential pathogens were also identified in the absence of clinical disease, indicating subclinical dynamics occurring that impact performance. Overall, this work provides necessary baseline data for the development of effective antibiotic alternatives, such as probiotics, for sustainable poultry production. Importance Multidrug resistant bacterial pathogens are perhaps the greatest medical challenge we will face in the 21 st century and beyond. Antibiotics are necessary in animal

Pathogen infection distribution and drug resistance analysis of patients with severe liver disease

Directory of Open Access Journals (Sweden)

Xi CHEN

2018-04-01

Full Text Available Objective　To explore the infection distribution and drug resistance of pathogens in patients with severe liver disease, and provide reference for clinical medication. Methods　Retrospective analysis of the microbiological specimens from patients with severe liver disease in Department of Infection of our hospital from August 2014 to November 2016 and the drug susceptibility testing were carried out by means of K-B disc diffusion method after bacterial culturing, and the distribution and drug resistance of pathogens were analyzed. Results　Totally 17 of 73 patients with severe liver disease developed hospital infection (23.3%. 104 strains of bacteria were isolated and 78 strains out of them were multidrug-resistant bacteria (75.0%. Among them, 28(26.9% strains were gram-positive coccus, mainly consisting of Staphylococcus aureus and Staphylococcus epidermidis, and 58(55.8% were gram-negative coccus, mainly composed of Escherichia coli, Klebsiella pneumonia and Acinetobacter baumannii, and 18(17.3% strains fungi. S.aureus and enterococci were resistant to penicillin, erythromycin and levofloxacin, the resistance rates were above 80.0%, but had low resistance rates to vancomycin, teicoplanin and tigecycline. The resistance rates of E.coli and K.pneumoniae to piperacillin, cefazolin and cefuroxime sodium were above 85.0%, but they had lower resistance rates to tigecycline and amikacin. Acinetobacter baumannii was 100% resistant to piperacillin and tazobactam, ceftazidime, imipenem and amikacin, but had low resistance to tigecycline and minocycline. Conclusions　Multi-drug resistant bacteria are the main bacterial pathogens in patients with severe liver disease and have a high resistance rate to commonly used antibiotics, empirical treatment in the population at high risk of multidrug-resistant bacteria infections requires the use of broad-spectrum or high-grade antibiotics (e.g. carbapenems or tigecycline and drugs against specific pathogenic

Antibiotic resistance in Burkholderia species.

Science.gov (United States)

Rhodes, Katherine A; Schweizer, Herbert P

2016-09-01

The genus Burkholderia comprises metabolically diverse and adaptable Gram-negative bacteria, which thrive in often adversarial environments. A few members of the genus are prominent opportunistic pathogens. These include Burkholderia mallei and Burkholderia pseudomallei of the B. pseudomallei complex, which cause glanders and melioidosis, respectively. Burkholderia cenocepacia, Burkholderia multivorans, and Burkholderia vietnamiensis belong to the Burkholderia cepacia complex and affect mostly cystic fibrosis patients. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. The first line of defense against antimicrobials in Burkholderia species is the outer membrane penetration barrier. Most Burkholderia contain a modified lipopolysaccharide that causes intrinsic polymyxin resistance. Contributing to reduced drug penetration are restrictive porin proteins. Efflux pumps of the resistance nodulation cell division family are major players in Burkholderia multidrug resistance. Third and fourth generation β-lactam antibiotics are seminal for treatment of Burkholderia infections, but therapeutic efficacy is compromised by expression of several β-lactamases and ceftazidime target mutations. Altered DNA gyrase and dihydrofolate reductase targets cause fluoroquinolone and trimethoprim resistance, respectively. Although antibiotic resistance hampers therapy of Burkholderia infections, the characterization of resistance mechanisms lags behind other non-enteric Gram-negative pathogens, especially ESKAPE bacteria such as Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa. Copyright © 2016 Elsevier Ltd. All rights reserved.

Persistence of bacterial pathogens, antibiotic resistance genes, and enterococci in tidal creek tributaries.

Science.gov (United States)

Jones, Chance E; Maddox, Anthony; Hurley, Dorset; Barkovskii, Andrei L

2018-05-19

Intertidal creeks form the primary hydrologic link between estuaries and land-based activities on barrier islands. Fecal indicators Enterococcus spp. (Entero1), pathogens Shigella spp. (ipaH), Salmonella spp. (invA), E. coli of EHEC/EPEC groups (eaeA), E. coli of EAEC, EIEC, and UPEC groups (set1B), E. coli of STEC group (stx1); and tetracycline resistance genes (tet(B), tet(C), tet(D), tet(E), tet(K), tet(Q), tet(W), and tet(X); TRG) were detected in the headwater of Oakdale Creek (Sapelo Island, GA) receiving runoffs from Hog Hammock village. Excavation of drainage ditches around the village caused a high increase in the incidence of the above determinants. Water samples were collected from the headwater, transferred to diffusion chambers, submersed in the headwater, saltmarsh, and mouth of the creek; and the determinants were monitored for 3 winter months. With some exceptions, their persistence decreased in order headwater > saltmarsh > mouth. Genes associated with Enterococcus spp. were the most persistent at all the sites, following in the headwater with determinants for Salmonella spp. and E. coli of EAEC, EIEC, and UPEC groups. In the mouth, the most persistent gene was eaeA indicating EHEC, EPEC, and STEC. Tet(B) and tet(C) persisted the longest in headwater and saltmarsh. No TRG persisted after 11 days in the mouth. Most determinants revealed correlations with temperature and pH, and inverse correlations with dissolved oxygen. Decay rates of the above determinants varied in the range of -0.02 to -0.81/day, and were up to 40 folds higher in the saltmarsh and mouth than in the headwater. Our data demonstrated that water parameters could to some extent predict a general trend in the fate of virulence and antibiotic resistance determinants in tidal creek tributaries but strongly suggested that their persistence in these tributaries cannot be predicted from that of enterococci, or extrapolated from one biological contaminant to another. Copyright

Resistance profile for pathogens causing urinary tract infection in a pediatric population, and antibiotic treatment response at a university hospital, 2010-2011.

Science.gov (United States)

Vélez Echeverri, Catalina; Serna-Higuita, Lina María; Serrano, Ana Katherina; Ochoa-García, Carolina; Rojas Rosas, Luisa; María Bedoya, Ana; Suárez, Margarita; Hincapié, Catalina; Henao, Adriana; Ortiz, Diana; Vanegas, Juan José; Zuleta, John Jairo; Espinal, David

2014-01-01

Urinary tract infection (UTI) is one of the most common bacterial infections in childhood and causes acute and chronic morbidity and long-term hypertension and chronic kidney disease. To describe the demographic characteristics, infectious agents, patterns of antibiotic resistance, etiologic agent and profile of susceptibility and response to empirical treatment of UTI in a pediatric population. This is a descriptive, retrospective study. Included in the study were 144 patients, 1:2.06 male to female ratio. The most common symptom was fever (79.9%) and 31.3% had a history of previous UTI. 72.0% of the patients had positive urine leukocyte count (>5 per field), urine gram was positive in 85.0% of samples and gram negative bacilli accounted for 77.8% for the total pathogens isolated. The most frequent uropathogens isolated were Escherichia coli and Klebsiella pneumoniae. Our E.coli isolates had a susceptibility rate higher than 90% to most of the antibiotics used, but a resistance rate of 42.6% to TMP SMX and 45.5% to ampicillin sulbactam. 6.3% of E. coli was extended-spectrum beta-lactamases producer strains. The most frequent empirical antibiotic used was amikacin, which was used in 66.0% of the patients. 17 of 90 patients who underwent voiding cistouretrography (VCUG) had vesicoureteral reflux. This study revealed that E. coli was the most frequent pathogen of community acquired UTI. We found that E. coli and other uropathogens had a high resistance rate against TMP SMX and ampicillin sulbactam. In order to ensure a successful empirical treatment, protocols should be based on local epidemiology and susceptibility rates.

Yeast cell wall extract induces disease resistance against bacterial and fungal pathogens in Arabidopsis thaliana and Brassica crop.

Directory of Open Access Journals (Sweden)

Mari Narusaka

Full Text Available Housaku Monogatari (HM is a plant activator prepared from a yeast cell wall extract. We examined the efficacy of HM application and observed that HM treatment increased the resistance of Arabidopsis thaliana and Brassica rapa leaves to bacterial and fungal infections. HM reduced the severity of bacterial leaf spot and anthracnose on A. thaliana and Brassica crop leaves with protective effects. In addition, gene expression analysis of A. thaliana plants after treatment with HM indicated increased expression of several plant defense-related genes. HM treatment appears to induce early activation of jasmonate/ethylene and late activation of salicylic acid (SA pathways. Analysis using signaling mutants revealed that HM required SA accumulation and SA signaling to facilitate resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola and the fungal pathogen Colletotrichum higginsianum. In addition, HM-induced resistance conferred chitin-independent disease resistance to bacterial pathogens in A. thaliana. These results suggest that HM contains multiple microbe-associated molecular patterns that activate defense responses in plants. These findings suggest that the application of HM is a useful tool that may facilitate new disease control methods.

Synthesis and Characterization of Cefotaxime Conjugated Gold Nanoparticles and Their Use to Target Drug-Resistant CTX-M-Producing Bacterial Pathogens.

Science.gov (United States)

Shaikh, Sibhghatulla; Rizvi, Syed Mohd Danish; Shakil, Shazi; Hussain, Talib; Alshammari, Thamir M; Ahmad, Waseem; Tabrez, Shams; Al-Qahtani, Mohammad H; Abuzenadah, Adel M

2017-09-01

Multidrug-resistance due to "β lactamases having the expanded spectrum" (ESBLs) in members of Enterobacteriaceae is a matter of continued clinical concern. CTX-M is among the most common ESBLs in Enterobacteriaceae family. In the present study, a nanoformulation of cefotaxime was prepared using gold nanoparticles to combat drug-resistance in ESBL producing strains. Here, two CTX-M-15 positive cefotaxime resistant bacterial strains (i.e., one Escherichia coli and one Klebsiella pneumoniae strain) were used for testing the efficacy of "cefotaxime loaded gold-nanoparticles." Bromelain was used for both reduction and capping in the process of synthesis of gold-nanoparticles. Thereafter, cefotaxime was conjugated onto it with the help of activator 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide. For characterization of both unconjugated and cefotaxime conjugated gold nanoparticles; UV-Visible spectroscopy, Scanning, and Transmission type Electron Microscopy methods accompanied with Dynamic Light Scattering were used. We used agar diffusion method plus microbroth-dilution method for the estimation of the antibacterial-activity and determination of minimum inhibitory concentration or MIC values, respectively. MIC values of cefotaxime loaded gold nanoparticles against E. coli and K. pneumoniae were obtained as 1.009 and 2.018 mg/L, respectively. These bacterial strains were completely resistant to cefotaxime alone. These results reinforce the utility of conjugating an old unresponsive antibiotic with gold nanoparticles to restore its efficacy against otherwise resistant bacterial pathogens. J. Cell. Biochem. 118: 2802-2808, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Urinary Tract Infection in Children: Management in the Era of Antibiotic Resistance-A Pediatric Urologist's View.

Science.gov (United States)

Kutasy, Balazs; Coyle, David; Fossum, Magdalena

2017-04-01

Antibiotic resistance to uropathogens has grown significantly worldwide. Today, pediatric urologist experience a situation that needs appropriate action because urinary tract infections are one of the most common bacterial infections in children. In this overview we aimed at presenting the clinical aspects of antibiotic usage in pediatric urology. Our intention was to take part of the important debate regarding future management of bacterial resistance against antibiotics. We searched PubMed for the terms: [UTI in children], [Recurrent UTI in children], and [Antibiotic resistance in UTI]. When using these terms, we found a numerous amount (3875) of published clinical articles related to the topic. By means of an overview, we chose not to focus on a specific condition but to an overall understanding of the problems related to pediatric urology in general. We found that usage of antibiotics has had an unquestionable benefit to reduce the morbidity and mortality related to urinary tract infections in childhood. However, recent studies suggest that early exposure to antibiotics in childhood might have negative systemic effects related to neurocognitive function, body metabolism, and fat distribution. In addition to increased resistance to common antimicrobial agents, it has resulted in increased costs and inadequate effect in severe infections. This calls for changes in the clinical management of urinary pathogens in pediatric urology. As the prevalence of antibiotic resistance grows, pediatric urologists have a key role in managing its consequences and its prevention. In this overview we looked at the consequences of antibiotic usage treating urinary tract infections in childhood. We found that the prevalence of antibiotic resistance has grown. We concluded that decision-makers must know about the short- and long-term effects of antibiotic usage in children. When we understand the development of antibiotic resistance better, we can build up prevention strategies

Using Natural Products to Treat Resistant and Persistent Bacterial Infections

Science.gov (United States)

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

Removal of bacterial contaminants and antibiotic resistance genes by conventional wastewater treatment processes in Saudi Arabia: Is the treated wastewater safe to reuse for agricultural irrigation?

KAUST Repository

Aljassim, Nada I.

2015-04-01

This study aims to assess the removal efficiency of microbial contaminants in a local wastewater treatment plant over the duration of one year, and to assess the microbial risk associated with reusing treated wastewater in agricultural irrigation. The treatment process achieved 3.5 logs removal of heterotrophic bacteria and up to 3.5 logs removal of fecal coliforms. The final chlorinated effluent had 1.8×102 MPN/100mL of fecal coliforms and fulfils the required quality for restricted irrigation. 16S rRNA gene-based high-throughput sequencing showed that several genera associated with opportunistic pathogens (e.g. Acinetobacter, Aeromonas, Arcobacter, Legionella, Mycobacterium, Neisseria, Pseudomonas and Streptococcus) were detected at relative abundance ranging from 0.014 to 21 % of the total microbial community in the influent. Among them, Pseudomonas spp. had the highest approximated cell number in the influent but decreased to less than 30 cells/100mL in both types of effluent. A culture-based approach further revealed that Pseudomonas aeruginosa was mainly found in the influent and non-chlorinated effluent but was replaced by other Pseudomonas spp. in the chlorinated effluent. Aeromonas hydrophila could still be recovered in the chlorinated effluent. Quantitative microbial risk assessment (QMRA) determined that only chlorinated effluent should be permitted for use in agricultural irrigation as it achieved an acceptable annual microbial risk lower than 10-4 arising from both P. aeruginosa and A. hydrophila. However, the proportion of bacterial isolates resistant to 6 types of antibiotics increased from 3.8% in the influent to 6.9% in the chlorinated effluent. Examples of these antibiotic-resistant isolates in the chlorinated effluent include Enterococcus and Enterobacter spp. Besides the presence of antibiotic-resistant bacterial isolates, tetracycline resistance genes tetO, tetQ, tetW, tetH, tetZ were also present at an average 2.5×102, 1.6×102, 4.4×102, 1

Graphene oxide in the water environment could affect tetracycline-antibiotic resistance.

Science.gov (United States)

Guo, Mei-Ting; Zhang, Guo-Sheng

2017-09-01

In recent years, the influence of new materials like nanoparticles in the water environment on biological substances has been widely studied. Antibiotic resistance genes (ARGs) represent a new type of pollutant in the environment. Graphene oxide (GO), as a nano material, because of its unique structure, may have an impact on antibiotic resistance bacteria (ARB) and ARGs; however the research in this area is rarely reported. Therefore, this study mainly investigated the effects of GO on bacterial antibiotic resistance. The results showed that GO had a limited effect on ARB inactivation. A high concentration of GO (>10 mg/L) can damage resistant plasmids to reduce bacterial resistance to antibiotics, but low concentrations of GO (antibiotic resistance needs further investigation. Copyright © 2017. Published by Elsevier Ltd.

A study of bacterial pathogens and antibiotic susceptibility patterns in chronic suppurative otitis media.

Science.gov (United States)

Mofatteh, M R; Shahabian Moghaddam, F; Yousefi, M; Namaei, M H

2018-01-01

To assess the frequency of bacterial agents in chronic suppurative otitis media and the antibiotic susceptibility patterns of isolates among patients. A total of 185 patients clinically diagnosed with chronic suppurative otitis media were interviewed and middle-ear effusion samples were collected using sterile swabs. All bacterial isolates were identified by conventional microbiological methods. Antibiotic susceptibility patterns of the isolates were determined by Kirby-Bauer disc diffusion. Staphylococci spp. (64.9 per cent) were the most prevalent bacteria isolated, followed by Klebsiella spp. (12.9 per cent) and Pseudomonas aeruginosa (10.3 per cent). The most effective antibiotic for treatment of bacterial chronic suppurative otitis media was ciprofloxacin. Statistical analysis showed no significant difference in bacterial infestations among chronic suppurative otitis media patients and the antimicrobial susceptibility patterns of the bacterial isolates based on gender and age (p > 0.05). Our findings highlight the importance of a continuous and periodic evaluation of the bacteriological profile and antibiotic susceptibility patterns in chronic suppurative otitis media patients for efficacious treatment of the infection.

Probiotic approach to prevent antibiotic resistance.

Science.gov (United States)

Ouwehand, Arthur C; Forssten, Sofia; Hibberd, Ashley A; Lyra, Anna; Stahl, Buffy

2016-01-01

Probiotics are live microorganisms, mainly belonging to the genera Lactobacillus and Bifidobacterium, although also strain of other species are commercialized, that have a beneficial effect on the host. From the perspective of antibiotic use, probiotics have been observed to reduce the risk of certain infectious disease such as certain types of diarrhea and respiratory tract infection. This may be accompanied with a reduced need of antibiotics for secondary infections. Antibiotics tend to be effective against most common diseases, but increasingly resistance is being observed among pathogens. Probiotics are specifically selected to not contribute to the spread of antibiotic resistance and not carry transferable antibiotic resistance. Concomitant use of probiotics with antibiotics has been observed to reduce the incidence, duration and/or severity of antibiotic-associated diarrhea. This contributes to better adherence to the antibiotic prescription and thereby reduces the evolution of resistance. To what extent probiotics directly reduce the spread of antibiotic resistance is still much under investigation; but maintaining a balanced microbiota during antibiotic use may certainly provide opportunities for reducing the spread of resistances. Key messages Probiotics may reduce the risk for certain infectious diseases and thereby reduce the need for antibiotics. Probiotics may reduce the risk for antibiotic-associated diarrhea Probiotics do not contribute to the spread of antibiotic resistance and may even reduce it.

A novel Erm monomethyltransferase in antibiotic-resistant isolates of Mannheimia haemolytica and Pasteurella multocida

DEFF Research Database (Denmark)

Desmolaize, Benoit; Rose, Simon; Warrass, Ralf

2011-01-01

Mannheimia haemolytica and Pasteurella multocida are aetiological agents commonly associated with respiratory tract infections in cattle. Recent isolates of these pathogens have been shown to be resistant to macrolides and other ribosome-targeting antibiotics. Direct analysis of the 23S r...... without any dimethyltransferase activity. Erm(42) is a novel addition to the Erm family: it is phylogenetically distant from the other Erm family members and it is unique in being a bona fide monomethyltransferase that is disseminated between bacterial pathogens....

Changes in Bacterial Resistance Patterns of Pediatric Urinary Tract Infections and Rationale for Empirical Antibiotic Therapy

Directory of Open Access Journals (Sweden)

İbrahim Gökçe

2017-10-01

Full Text Available Background: The causative agent spectrum and resistance patterns of urinary tract infections in children are affected by many factors. Aims: To demonstrate antibiotic resistance in urinary tract infections and changing ratio in antibiotic resistance by years. Study Design: Retrospective cross-sectional study. Methods: We analysed antibiotic resistance patterns of isolated Gram (- bacteria during the years 2011-2014 (study period 2 in children with urinary tract infections. We compared these findings with data collected in the same centre in 2001-2003 (study period 1. Results: Four hundred and sixty-five uncomplicated community-acquired Gram (- urinary tract infections were analysed from 2001-2003 and 400 from 2011-2014. Sixty-one percent of patients were female (1.5 girls : 1 boy. The mean age of children included in the study was 3 years and 9 months. Escherichia coli was the predominant bacteria isolated during both periods of the study (60% in study period 1 and 73% in study period 2. Bacteria other than E. coli demonstrated a higher level of resistance to all of the antimicrobials except trimethoprim-sulfamethoxazole than E. coli bacteria during the years 2011-2014. In our study, we found increasing resistance trends of urinary pathogens for cefixime (from 1% to 15%, p0.05. Conclusion: In childhood urinary tract infections, antibiotic resistance should be evaluated periodically and empiric antimicrobial therapy should be decided according to antibiotic sensitivity results

Isolation, Functional Characterization and Transmissibility of p3PS10, a Multidrug Resistance Plasmid of the Fish Pathogen Piscirickettsia salmonis

Directory of Open Access Journals (Sweden)

José Saavedra

2018-05-01

Full Text Available Antibiotic resistance is a major public health concern due to its association with the loss of efficacy of antimicrobial therapies. Horizontal transfer events may play a significant role in the dissemination of resistant bacterial phenotypes, being mobilizable plasmids a well-known mechanism. In this study, we aimed to gain insights into the genetics underlying the development of antibiotic resistance by Piscirickettsia salmonis isolates, a bacterial fish pathogen and causative agent of salmonid piscirickettsiosis, and the main target of antibiotics used in Chilean salmon farming. We provide experimental evidence that the plasmid p3PS10, which harbors multidrug resistance genes for chloramphenicol (cat2, tetracyclines [tet(31], aminoglycosides (sat1 and aadA1, and sulfonamides (sul2, is carried by a group of P. salmonis isolates exhibiting a markedly reduced susceptibility to oxytetracycline in vitro (128–256 μg/mL of minimal inhibitory concentration, MIC. Antibiotic susceptibility analysis extended to those antibiotics showed that MIC of chloramphenicol, streptomycin, and sulfamethoxazole/trimethoprim were high, but the MIC of florfenicol remained at the wild-type level. By means of molecular cloning, we demonstrate that those genes encoding putative resistance markers are indeed functional. Interestingly, mating assays clearly show that p3PS10 is able to be transferred into and replicate in different hosts, thereby conferring phenotypes similar to those found in the original host. According to epidemiological data, this strain is distributed across aquaculture settings in southern Chile and is likely to be responsible for oxytetracycline treatment failures. This work demonstrates that P. salmonis is more versatile than it was thought, capable of horizontally transferring DNA, and probably playing a role as a vector of resistance traits among the seawater bacterial population. However, the low transmission frequency of p3PS10 suggests a

Antibiotic Resistance of Diverse Bacteria from Aquaculture in Borneo

Directory of Open Access Journals (Sweden)

M. M. Kathleen

2016-01-01

Full Text Available The administration of antimicrobials in aquaculture provides a selective pressure creating a reservoir of multiple resistant bacteria in the cultured fish and shrimps as well as the aquaculture environment. The objective of this study was to determine the extent of antibiotic resistance in aquaculture products and aquaculture’s surrounding environment in Sarawak, Malaysian Borneo. Ninety-four identified bacterial isolates constituted of 17 genera were isolated from sediment, water, and cultured organisms (fish and shrimp in selected aquaculture farms. These isolates were tested for their antibiotic resistance against 22 antibiotics from several groups using the disk diffusion method. The results show that the highest resistance was observed towards streptomycin (85%, n=20, while the lowest resistance was towards gentamicin (1.1%, n=90. The multiple antibiotic resistant (MAR index of the isolates tested ranged between 0 and 0.63. It was suggested that isolates with MAR index > 0.2 were recovered from sources with high risk of antibiotic resistant contamination. This study revealed low level of antibiotic resistance in the aquaculture bacterial isolates except for streptomycin and ampicillin (>50% resistance, n=94 which have been used in the aquaculture industry for several decades. Antibiotic resistant patterns should be continuously monitored to predict the emergence and widespread of MAR. Effective action is needed to keep the new resistance from further developing and spreading.

Repurposing Clinical Molecule Ebselen to Combat Drug Resistant Pathogens.

Science.gov (United States)

Thangamani, Shankar; Younis, Waleed; Seleem, Mohamed N

2015-01-01

Without a doubt, our current antimicrobials are losing the battle in the fight against newly-emerged multidrug-resistant pathogens. There is a pressing, unmet need for novel antimicrobials and novel approaches to develop them; however, it is becoming increasingly difficult and costly to develop new antimicrobials. One strategy to reduce the time and cost associated with antimicrobial innovation is drug repurposing, which is to find new applications outside the scope of the original medical indication of the drug. Ebselen, an organoselenium clinical molecule, possesses potent antimicrobial activity against clinical multidrug-resistant Gram-positive pathogens, including Staphylococcus, Streptococcus, and Enterococcus, but not against Gram-negative pathogens. Moreover, the activity of ebselen against Gram-positive pathogens exceeded those activities determined for vancomycin and linezolid, drugs of choice for treatment of Enterococcus and Staphylococcus infections. The minimum inhibitory concentrations of ebselen at which 90% of clinical isolates of Enterococcus and Staphylococcus were inhibited (MIC90) were found to be 0.5 and 0.25 mg/L, respectively. Ebselen showed significant clearance of intracellular methicillin-resistant S. aureus (MRSA) in comparison to vancomycin and linezolid. We demonstrated that ebselen inhibits the bacterial translation process without affecting mitochondrial biogenesis. Additionally, ebselen was found to exhibit excellent activity in vivo in a Caenorhabditis elegans MRSA-infected whole animal model. Finally, ebselen showed synergistic activities with conventional antimicrobials against MRSA. Taken together, our results demonstrate that ebselen, with its potent antimicrobial activity and safety profiles, can be potentially used to treat multidrug resistant Gram-positive bacterial infections alone or in combination with other antibiotics and should be further clinically evaluated.

Photodynamic inactivation of antibiotic-resistant pathogens

International Nuclear Information System (INIS)

Paronyan, M.H.

2015-01-01

Nowadays methicillin-resistant strain Staphylococcus aureus (MRSA) is one of the most widespread multiresistant bacteria. Photodynamic inactivation (PDI) of microorganisms by photosensitizers (PS) may be an effective and alternative therapeutic option against antibiotic resistant bacteria. The effectiveness of new PS cationic porphyrin Zn-TBut4PyP was tested on two strains of S. aureus (MRSA and methicillin-sensitive S. aureus). It is shown that Zn-TBut4PyP has high photodynamic activity against both strains

Analyzing indicator microorganisms, antibiotic resistant Escherichia coli, and regrowth potential of foodborne pathogens in various organic fertilizers.

Science.gov (United States)

Miller, Cortney; Heringa, Spencer; Kim, Jinkyung; Jiang, Xiuping

2013-06-01

This study analyzed various organic fertilizers for indicator microorganisms, pathogens, and antibiotic-resistant Escherichia coli, and evaluated the growth potential of E. coli O157:H7 and Salmonella in fertilizers. A microbiological survey was conducted on 103 organic fertilizers from across the United States. Moisture content ranged from approximately 1% to 86.4%, and the average pH was 7.77. The total aerobic mesophiles ranged from approximately 3 to 9 log colony-forming units (CFU)/g. Enterobacteriaceae populations were in the range of fertilizer, respectively, whereas E. coli O157:H7 grew approximately 4.6, 4.0, 4.0, and 4.8 log CFU/g, respectively. Our results revealed that the microbiological quality of organic fertilizers varies greatly, with some fertilizers containing antibiotic resistant E. coli and a few supporting the growth of foodborne pathogens after reintroduction into the fertilizer.

Occurrence of Antibiotic Resistance Genes and Bacterial Markers in a Tropical River Receiving Hospital and Urban Wastewaters.

Directory of Open Access Journals (Sweden)

Naresh Devarajan

Full Text Available The occurrence of emerging biological contaminants including antibiotic resistance genes (ARGs and Faecal Indicator Bacteria (FIB is still little investigated in developing countries under tropical conditions. In this study, the total bacterial load, the abundance of FIB (E. coli and Enterococcus spp. (ENT, Pseudomonas spp. and ARGs (blaTEM, blaCTX-M, blaSHV, blaNDM and aadA were quantified using quantitative PCR in the total DNA extracted from the sediments recovered from hospital outlet pipes (HOP and the Cauvery River Basin (CRB, Tiruchirappalli, Tamil Nadu, India. The abundance of bacterial marker genes were 120, 104 and 89 fold higher for the E. coli, Enterococcus spp. and Pseudomonas spp., respectively at HOP when compared with CRB. The ARGs aadA and blaTEM were most frequently detected in higher concentration than other ARGs at all the sampling sites. The ARGs blaSHV and blaNDM were identified in CRB sediments contaminated by hospital and urban wastewaters. The ARGs abundance strongly correlated (r ≥ 0.36, p < 0.05, n = 45 with total bacterial load and E. coli in the sediments, indicating a common origin and extant source of contamination. Tropical aquatic ecosystems receiving wastewaters can act as reservoir of ARGs, which could potentially be transferred to susceptible bacterial pathogens at these sites.

Temperate and lytic bacteriophages programmed to sensitize and kill antibiotic-resistant bacteria.

Science.gov (United States)

Yosef, Ido; Manor, Miriam; Kiro, Ruth; Qimron, Udi

2015-06-09

The increasing threat of pathogen resistance to antibiotics requires the development of novel antimicrobial strategies. Here we present a proof of concept for a genetic strategy that aims to sensitize bacteria to antibiotics and selectively kill antibiotic-resistant bacteria. We use temperate phages to deliver a functional clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) system into the genome of antibiotic-resistant bacteria. The delivered CRISPR-Cas system destroys both antibiotic resistance-conferring plasmids and genetically modified lytic phages. This linkage between antibiotic sensitization and protection from lytic phages is a key feature of the strategy. It allows programming of lytic phages to kill only antibiotic-resistant bacteria while protecting antibiotic-sensitized bacteria. Phages designed according to this strategy may be used on hospital surfaces and hand sanitizers to facilitate replacement of antibiotic-resistant pathogens with sensitive ones.

Influence of Chicken Manure Fertilization on Antibiotic-Resistant Bacteria in Soil and the Endophytic Bacteria of Pakchoi

Directory of Open Access Journals (Sweden)

Qingxiang Yang

2016-06-01

Full Text Available Animal manure is commonly used as fertilizer for agricultural crops worldwide, even though it is believed to contribute to the spread of antibiotic resistance from animal intestines to the soil environment. However, it is unclear whether and how there is any impact of manure fertilization on populations and community structure of antibiotic-resistant endophytic bacteria (AREB in plant tissues. To investigate the effect of manure and organic fertilizer on endophytic bacterial communities, pot experiments were performed with pakchoi grown with the following treatments: (1 non-treated; (2 chicken manure-treated and (3 organic fertilizer-treated. Manure or organic fertilizer significantly increased the abundances of total cultivable endophytic bacteria (TCEB and AREB in pakchoi, and the effect of chicken manure was greater than that of organic fertilizer. Further, 16S rDNA sequencing and the phylogenetic analysis indicated that chicken manure or organic fertilizer application increased the populations of multiple antibiotic-resistant bacteria (MARB in soil and multiple antibiotic-resistant endophytic bacteria (MAREB in pakchoi. The identical multiple antibiotic-resistant bacterial populations detected in chicken manure, manure- or organic fertilizer-amended soil and the vegetable endophytic system were Brevundimonas diminuta, Brachybacterium sp. and Bordetella sp., suggesting that MARB from manure could enter and colonize the vegetable tissues through manure fertilization. The fact that some human pathogens with multiple antibiotic resistance were detected in harvested vegetables after growing in manure-amended soil demonstrated a potential threat to human health.

Environmental factors influencing the development and spread of antibiotic resistance.

Science.gov (United States)

Bengtsson-Palme, Johan; Kristiansson, Erik; Larsson, D G Joakim

2018-01-01

Antibiotic resistance and its wider implications present us with a growing healthcare crisis. Recent research points to the environment as an important component for the transmission of resistant bacteria and in the emergence of resistant pathogens. However, a deeper understanding of the evolutionary and ecological processes that lead to clinical appearance of resistance genes is still lacking, as is knowledge of environmental dispersal barriers. This calls for better models of how resistance genes evolve, are mobilized, transferred and disseminated in the environment. Here, we attempt to define the ecological and evolutionary environmental factors that contribute to resistance development and transmission. Although mobilization of resistance genes likely occurs continuously, the great majority of such genetic events do not lead to the establishment of novel resistance factors in bacterial populations, unless there is a selection pressure for maintaining them or their fitness costs are negligible. To enable preventative measures it is therefore critical to investigate under what conditions and to what extent environmental selection for resistance takes place. In addition, understanding dispersal barriers is not only key to evaluate risks, but also to prevent resistant pathogens, as well as novel resistance genes, from reaching humans. © FEMS 2017.

Fitness and Recovery of Bacterial Communities and Antibiotic Resistance Genes in Urban Wastewaters Exposed to Classical Disinfection Treatments.

Science.gov (United States)

Di Cesare, Andrea; Fontaneto, Diego; Doppelbauer, Julia; Corno, Gianluca

2016-09-20

Antibiotic resistance genes (ARGs) are increasingly appreciated to be important as micropollutants. Indirectly produced by human activities, they are released into the environment, as they are untargeted by conventional wastewater treatments. In order to understand the fate of ARGs and of other resistant forms (e.g., phenotypical adaptations) in urban wastewater treatment plants (WWTPs), we monitored three WWTPs with different disinfection processes (chlorine, peracetic acid (PAA), and ultraviolet light (UV)). We monitored WWTPs influx and pre- and postdisinfection effluent over 24 h, followed by incubation experiments lasting for 96 h. We measured bacterial abundance, size distribution and aggregational behavior, the proportion of intact (active) cells, and the abundances of four ARGs and of the mobile element integron1. While all the predisinfection treatments of all WWTPs removed the majority of bacteria and of associated ARGs, of the disinfection processes only PAA efficiently removed bacterial cells. However, the stress imposed by PAA selected for bacterial aggregates and, similarly to chlorine, stimulated the selection of ARGs during the incubation experiment. This suggests disinfections based on chemically aggressive destruction of bacterial cell structures can promote a residual microbial community that is more resistant to antibiotics and, given the altered aggregational behavior, to competitive stress in nature.

Predictable Phenotypes of Antibiotic Resistance Mutations.

Science.gov (United States)

Knopp, M; Andersson, D I

2018-05-15

Antibiotic-resistant bacteria represent a major threat to our ability to treat bacterial infections. Two factors that determine the evolutionary success of antibiotic resistance mutations are their impact on resistance level and the fitness cost. Recent studies suggest that resistance mutations commonly show epistatic interactions, which would complicate predictions of their stability in bacterial populations. We analyzed 13 different chromosomal resistance mutations and 10 host strains of Salmonella enterica and Escherichia coli to address two main questions. (i) Are there epistatic interactions between different chromosomal resistance mutations? (ii) How does the strain background and genetic distance influence the effect of chromosomal resistance mutations on resistance and fitness? Our results show that the effects of combined resistance mutations on resistance and fitness are largely predictable and that epistasis remains rare even when up to four mutations were combined. Furthermore, a majority of the mutations, especially target alteration mutations, demonstrate strain-independent phenotypes across different species. This study extends our understanding of epistasis among resistance mutations and shows that interactions between different resistance mutations are often predictable from the characteristics of the individual mutations. IMPORTANCE The spread of antibiotic-resistant bacteria imposes an urgent threat to public health. The ability to forecast the evolutionary success of resistant mutants would help to combat dissemination of antibiotic resistance. Previous studies have shown that the phenotypic effects (fitness and resistance level) of resistance mutations can vary substantially depending on the genetic context in which they occur. We conducted a broad screen using many different resistance mutations and host strains to identify potential epistatic interactions between various types of resistance mutations and to determine the effect of strain

A systematic review and meta-analysis of the effects of antibiotic consumption on antibiotic resistance.

NARCIS (Netherlands)

Bell, B.G.; Schellevis, F.; Stobberingh, E.; Goossen, H.; Pringle, M.

2014-01-01

Background: Greater use of antibiotics during the past 50 years has exerted selective pressure on susceptible bacteria and may have favoured the survival of resistant strains. Existing information on antibiotic resistance patterns from pathogens circulating among community-based patients is

A systematic review and meta-analysis of the effects of antibiotic consumption on antibiotic resistance

NARCIS (Netherlands)

Bell, B.G.; Schellevis, F.; Stobberingh, E.; Goossens, H.; Pringle, M.

2014-01-01

Background: Greater use of antibiotics during the past 50 years has exerted selective pressure on susceptible bacteria and may have favoured the survival of resistant strains. Existing information on antibiotic resistance patterns from pathogens circulating among community-based patients is

Antibiotic sensitivities of common bacterial pathogens in urinary tract ...

African Journals Online (AJOL)

Of the total isolates 71.5% were Gram negatives. Sensitivity tested against ten antibiotics showed that resistance was common, and the effectiveness of tetracycline, ampicillin, co-trimoxazole, chloramphenicol and penicillin was under 50.0%. The resistance rate was 71.5%, 62.2%, and 62.2%, 54.7% and 40.8%, respectively ...

Emergence and dissemination of antibiotic resistance: A global problem

Directory of Open Access Journals (Sweden)

R Choudhury

2012-01-01

Full Text Available Antibiotic resistance is a major problem in clinical health settings. Interestingly the origin of many of antibiotic resistance mechanisms can be traced back to non-pathogenic environmental organisms. Important factors leading to the emergence and spread of antibiotic resistance include absence of regulation in the use of antibiotics, improper waste disposal and associated transmission of antibiotic resistance genes in the community through commensals. In this review, we discussed the impact of globalisation on the transmission of antibiotic resistance genes in bacteria through immigration and export/import of foodstuff. The significance of surveillance to define appropriate use of antibiotics in the clinic has been included as an important preventive measure.

Preliminary survey of antibiotic-resistant fecal indicator bacteria and pathogenic Escherichia coli from river-water samples collected in Oakland County, Michigan, 2003

Science.gov (United States)

Fogarty, Lisa R.; Duris, Joseph W.; Aichele, Stephen S.

2005-01-01

A preliminary study was done in Oakland County, Michigan, to determine the concentration of fecal indicator bacteria (fecal coliform bacteria and enterococci), antibiotic resistance patterns of these two groups, and the presence of potentially pathogenic Escherichia coli (E. coli). For selected sites, specific members of these groups [E. coli, Enterococcus faecium (E. faecium) and Enterococcus faecalis (E. faecalis)] were isolated and tested for levels of resistance to specific antibiotics used to treat human infections by pathogens in these groups and for their potential to transfer these resistances. In addition, water samples from all sites were tested for indicators of potentially pathogenic E. coli by three assays: a growth-based assay for sorbitol-negative E. coli, an immunological assay for E. coli O157, and a molecular assay for three virulence and two serotype genes. Samples were also collected from two non-urbanized sites outside of Oakland County. Results from the urbanized Oakland County area were compared to those from these two non-urbanized sites. Fecal indicator bacteria concentrations exceeded State of Michigan recreational water-quality standards and (or) recommended U.S. Environmental Protection Agency (USEPA) standards in samples from all but two Oakland County sites. Multiple-antibiotic-resistant fecal coliform bacteria were found at all sites, including two reference sites from outside the county. Two sites (Stony Creek and Paint Creek) yielded fecal coliform isolates resistant to all tested antibiotics. Patterns indicative of extended-spectrum-β-lactamase (ESBL)- producing fecal coliform bacteria were found at eight sites in Oakland County and E. coli resistant to clinically significant antibiotics were recovered from the River Rouge, Clinton River, and Paint Creek. Vancomycin-resistant presumptive enterococci were found at six sites in Oakland County and were not found at the reference sites. Evidence of acquired antibiotic resistances was

Cooperative Antibiotic Resistance in a Multi-Drug Environment

Science.gov (United States)

Yurtsev, Eugene; Dai, Lei; Gore, Jeff

2013-03-01

The emergence of antibiotic resistance in bacteria is a significant health concern. A frequent mechanism of antibiotic resistance involves the production of an enzyme which inactivates the antibiotic. By inactivating the antibiotic, resistant cells can ``share'' their resistance with other cells in the bacterial population, suggesting that it may be possible to observe cooperation between strains that inactivate different antibiotics. Here, we experimentally track the population dynamics of two E. coli strains in the presence of two different antibiotics. We find that together the strains are able to grow in antibiotic concentrations that inhibit growth of either of the strains individually. We observe that even when there is stable coexistence between the two strains, the population size of each strain can undergo large oscillations. We expect that our results will provide insight into the evolution of antibiotic resistance and the evolutionary origin of phenotypic diversity and cooperative behaviors.

High Levels of Antibiotic Resistance but No Antibiotic Production Detected Along a Gypsum Gradient in Great Onyx Cave, KY, USA

Directory of Open Access Journals (Sweden)

Kathleen Lavoie

2017-09-01

Full Text Available A preliminary study of antibiotic production and antibiotic resistance was conducted in Great Onyx Cave in Mammoth Cave National Park, KY, to determine if gypsum (CaSO4∙2H2O affects these bacterial activities. The cave crosses through the width of Flint Ridge, and passages under the sandstone caprock are dry with different amounts of gypsum. The Great Kentucky Desert hypothesis posits that gypsum limits the distribution of invertebrates in the central areas of Great Onyx Cave. Twenty-four bacterial isolates were cultivated from swabs and soils. Using three methods (soil crumb, soil crumb with indicator bacteria, and the cross-streak method using isolated bacteria we did not detect any production of antibiotics. Antibiotic resistance was widespread, with all 24 isolates resistant to a minimum of two antibiotics of seven tested, with three isolates resistant to all. Antibiotic resistance was high and not correlated with depth into the cave or the amount of gypsum. The Great Kentucky Desert hypothesis of the negative effects of gypsum seems to have no impact on bacterial activity.

Abundances of Clinically Relevant Antibiotic Resistance Genes and Bacterial Community Diversity in the Weihe River, China

Directory of Open Access Journals (Sweden)

Xiaojuan Wang

2018-04-01

Full Text Available The spread of antibiotic resistance genes in river systems is an emerging environmental issue due to their potential threat to aquatic ecosystems and public health. In this study, we used droplet digital polymerase chain reaction (ddPCR to evaluate pollution with clinically relevant antibiotic resistance genes (ARGs at 13 monitoring sites along the main stream of the Weihe River in China. Six clinically relevant ARGs and a class I integron-integrase (intI1 gene were analyzed using ddPCR, and the bacterial community was evaluated based on the bacterial 16S rRNA V3–V4 regions using MiSeq sequencing. The results indicated Proteobacteria, Actinobacteria, Cyanobacteria, and Bacteroidetes as the dominant phyla in the water samples from the Weihe River. Higher abundances of blaTEM, strB, aadA, and intI1 genes (103 to 105 copies/mL were detected in the surface water samples compared with the relatively low abundances of strA, mecA, and vanA genes (0–1.94 copies/mL. Eight bacterial genera were identified as possible hosts of the intI1 gene and three ARGs (strA, strB, and aadA based on network analysis. The results suggested that the bacterial community structure and horizontal gene transfer were associated with the variations in ARGs.

The Bacterial Mobile Resistome Transfer Network Connecting the Animal and Human Microbiomes.

Science.gov (United States)

Hu, Yongfei; Yang, Xi; Li, Jing; Lv, Na; Liu, Fei; Wu, Jun; Lin, Ivan Y C; Wu, Na; Weimer, Bart C; Gao, George F; Liu, Yulan; Zhu, Baoli

2016-11-15

Horizontally acquired antibiotic resistance genes (ARGs) in bacteria are highly mobile and have been ranked as principal risk resistance determinants. However, the transfer network of the mobile resistome and the forces driving mobile ARG transfer are largely unknown. Here, we present the whole profile of the mobile resistome in 23,425 bacterial genomes and explore the effects of phylogeny and ecology on the recent transfer (≥99% nucleotide identity) of mobile ARGs. We found that mobile ARGs are mainly present in four bacterial phyla and are significantly enriched in Proteobacteria The recent mobile ARG transfer network, which comprises 703 bacterial species and 16,859 species pairs, is shaped by the bacterial phylogeny, while an ecological barrier also exists, especially when interrogating bacteria colonizing different human body sites. Phylogeny is still a driving force for the transfer of mobile ARGs between farm animals and the human gut, and, interestingly, the mobile ARGs that are shared between the human and animal gut microbiomes are also harbored by diverse human pathogens. Taking these results together, we suggest that phylogeny and ecology are complementary in shaping the bacterial mobile resistome and exert synergistic effects on the development of antibiotic resistance in human pathogens. The development of antibiotic resistance threatens our modern medical achievements. The dissemination of antibiotic resistance can be largely attributed to the transfer of bacterial mobile antibiotic resistance genes (ARGs). Revealing the transfer network of these genes in bacteria and the forces driving the gene flow is of great importance for controlling and predicting the emergence of antibiotic resistance in the clinic. Here, by analyzing tens of thousands of bacterial genomes and millions of human and animal gut bacterial genes, we reveal that the transfer of mobile ARGs is mainly controlled by bacterial phylogeny but under ecological constraints. We also found

Impact of fertilizing with raw or anaerobically digested sewage sludge on the abundance of antibiotic-resistant coliforms, antibiotic resistance genes, and pathogenic bacteria in soil and on vegetables at harvest.

Science.gov (United States)

Rahube, Teddie O; Marti, Romain; Scott, Andrew; Tien, Yuan-Ching; Murray, Roger; Sabourin, Lyne; Zhang, Yun; Duenk, Peter; Lapen, David R; Topp, Edward

2014-11-01

The consumption of crops fertilized with human waste represents a potential route of exposure to antibiotic-resistant fecal bacteria. The present study evaluated the abundance of bacteria and antibiotic resistance genes by using both culture-dependent and molecular methods. Various vegetables (lettuce, carrots, radish, and tomatoes) were sown into field plots fertilized inorganically or with class B biosolids or untreated municipal sewage sludge and harvested when of marketable quality. Analysis of viable pathogenic bacteria or antibiotic-resistant coliform bacteria by plate counts did not reveal significant treatment effects of fertilization with class B biosolids or untreated sewage sludge on the vegetables. Numerous targeted genes associated with antibiotic resistance and mobile genetic elements were detected by PCR in soil and on vegetables at harvest from plots that received no organic amendment. However, in the season of application, vegetables harvested from plots treated with either material carried gene targets not detected in the absence of amendment. Several gene targets evaluated by using quantitative PCR (qPCR) were considerably more abundant on vegetables harvested from sewage sludge-treated plots than on vegetables from control plots in the season of application, whereas vegetables harvested the following year revealed no treatment effect. Overall, the results of the present study suggest that producing vegetable crops in ground fertilized with human waste without appropriate delay or pretreatment will result in an additional burden of antibiotic resistance genes on harvested crops. Managing human exposure to antibiotic resistance genes carried in human waste must be undertaken through judicious agricultural practice. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Effect of Vibration on Bacterial Growth and Antibiotic Resistance

Science.gov (United States)

Juergensmeyer, Elizabeth A.; Juergensmeyer, Margaret A.

2004-01-01

The purpose of this research grant was to provide a fundamental, systematic investigation of the effects of oscillatory acceleration on bacterial proliferation and their responses to antibiotics in a liquid medium.

Repurposing Clinical Molecule Ebselen to Combat Drug Resistant Pathogens.

Directory of Open Access Journals (Sweden)

Shankar Thangamani

Full Text Available Without a doubt, our current antimicrobials are losing the battle in the fight against newly-emerged multidrug-resistant pathogens. There is a pressing, unmet need for novel antimicrobials and novel approaches to develop them; however, it is becoming increasingly difficult and costly to develop new antimicrobials. One strategy to reduce the time and cost associated with antimicrobial innovation is drug repurposing, which is to find new applications outside the scope of the original medical indication of the drug. Ebselen, an organoselenium clinical molecule, possesses potent antimicrobial activity against clinical multidrug-resistant Gram-positive pathogens, including Staphylococcus, Streptococcus, and Enterococcus, but not against Gram-negative pathogens. Moreover, the activity of ebselen against Gram-positive pathogens exceeded those activities determined for vancomycin and linezolid, drugs of choice for treatment of Enterococcus and Staphylococcus infections. The minimum inhibitory concentrations of ebselen at which 90% of clinical isolates of Enterococcus and Staphylococcus were inhibited (MIC90 were found to be 0.5 and 0.25 mg/L, respectively. Ebselen showed significant clearance of intracellular methicillin-resistant S. aureus (MRSA in comparison to vancomycin and linezolid. We demonstrated that ebselen inhibits the bacterial translation process without affecting mitochondrial biogenesis. Additionally, ebselen was found to exhibit excellent activity in vivo in a Caenorhabditis elegans MRSA-infected whole animal model. Finally, ebselen showed synergistic activities with conventional antimicrobials against MRSA. Taken together, our results demonstrate that ebselen, with its potent antimicrobial activity and safety profiles, can be potentially used to treat multidrug resistant Gram-positive bacterial infections alone or in combination with other antibiotics and should be further clinically evaluated.

Susceptibility of bacterial isolates from community-acquired infections in sub-Saharan Africa and Asia to macrolide antibiotics.

Science.gov (United States)

Lubell, Yoel; Turner, Paul; Ashley, Elizabeth A; White, Nicholas J

2011-10-01

To review the literature on the susceptibility of common community pathogens in sub-Saharan Africa and Asia to the macrolide antibiotics. Inclusion criteria required that isolates were collected since 2004 to ensure results were of contemporary relevance. The data were aggregated by region, age group and sterility of site of culture sample. A total of 51 studies were identified, which reported the macrolide antimicrobial susceptibilities of common bacterial pathogens isolated since 2004. In general, there was less macrolide resistance in African than in Asian isolates. Most African studies reported high levels of macrolide susceptibility in Streptococcus pneumoniae, whereas most Chinese studies reported high levels of resistance. There was very little information available for Gram-negative organisms. Susceptibility of the pneumococcus to macrolides in SSA remains high in many areas, and good activity of azithromycin has been shown against Salmonellae spp. in Asia. In urban areas where high antibiotic consumption is prevalent, there was evidence of increased resistance to macrolides. However, there is no information on susceptibility from large areas in both continents. © 2011 Blackwell Publishing Ltd.

Nosocomial spontaneous bacterial peritonitis antibiotic treatment in the era of multi-drug resistance pathogens: A systematic review.

Science.gov (United States)

Fiore, Marco; Maraolo, Alberto Enrico; Gentile, Ivan; Borgia, Guglielmo; Leone, Sebastiano; Sansone, Pasquale; Passavanti, Maria Beatrice; Aurilio, Caterina; Pace, Maria Caterina

2017-07-07

To systematically review literature upon aetiology of nosocomial spontaneous bacterial peritonitis (N-SBP) given the rising importance of multidrug-resistant (MDR) bacteria. A literature search was performed on MEDLINE and Google Scholar databases from 2000 to 15 th of November 2016, using the following search strategy: "spontaneous" AND "peritonitis". The initial search through electronic databases retrieved 2556 records. After removing duplicates, 1958 records remained. One thousand seven hundred and thirty-five of them were excluded on the basis of the screening of titles and abstract, and the ensuing number of remaining articles was 223. Of these records, after careful evaluation, only 9 were included in the qualitative analysis. The overall proportion of MDR bacteria turned out to be from 22% to 73% of cases across the studies. N-SBP is caused, in a remarkable proportion, by MDR pathogens. This should prompt a careful re-assessment of guidelines addressing the treatment of this clinical entity.

Suppression of Emergence of Resistance in Pathogenic Bacteria: Keeping Our Powder Dry, Part 1.

Science.gov (United States)

Drusano, G L; Louie, Arnold; MacGowan, Alasdair; Hope, William

2015-12-28

We are in a crisis of bacterial resistance. For economic reasons, most pharmaceutical companies are abandoning antimicrobial discovery efforts, while, in health care itself, infection control and antibiotic stewardship programs have generally failed to prevent the spread of drug-resistant bacteria. At this point, what can be done? The first step has been taken. Governments and international bodies have declared there is a worldwide crisis in antibiotic drug resistance. As discovery efforts begin anew, what more can be done to protect newly developing agents and improve the use of new drugs to suppress resistance emergence? A neglected path has been the use of recent knowledge regarding antibiotic dosing as single agents and in combination to minimize resistance emergence, while also providing sufficient early bacterial kill. In this review, we look at the data for resistance suppression. Approaches include increasing the intensity of therapy to suppress resistant subpopulations; developing concepts of clinical breakpoints to include issues surrounding suppression of resistance; and paying attention to the duration of therapy, which is another important issue for resistance suppression. New understanding of optimizing combination therapy is of interest for difficult-to-treat pathogens like Pseudomonas aeruginosa, Acinetobacter spp., and multidrug-resistant (MDR) Enterobacteriaceae. These lessons need to be applied to our old drugs to preserve them as well and need to be put into national and international antibiotic resistance strategies. As importantly, from a regulatory perspective, new chemical entities should have a corresponding resistance suppression plan at the time of regulatory review. In this way, we can make the best of our current situation and improve future prospects. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Suppression of Emergence of Resistance in Pathogenic Bacteria: Keeping Our Powder Dry, Part 2.

Science.gov (United States)

Drusano, G L; Hope, William; MacGowan, Alasdair; Louie, Arnold

2015-12-28

We are in a crisis of bacterial resistance. For economic reasons, most pharmaceutical companies are abandoning antimicrobial discovery efforts, while, in health care itself, infection control and antibiotic stewardship programs have generally failed to prevent the spread of drug-resistant bacteria. At this point, what can be done? The first step has been taken. Governments and international bodies have declared there is a worldwide crisis in antibiotic drug resistance. As discovery efforts begin anew, what more can be done to protect newly developing agents and improve the use of new drugs to suppress resistance emergence? A neglected path has been the use of recent knowledge regarding antibiotic dosing as single agents and in combination to minimize resistance emergence, while also providing sufficient early bacterial kill. In this review, we look at the data for resistance suppression. Approaches include increasing the intensity of therapy to suppress resistant subpopulations; developing concepts of clinical breakpoints to include issues surrounding suppression of resistance; and paying attention to the duration of therapy, which is another important issue for resistance suppression. New understanding of optimizing combination therapy is of interest for difficult-to-treat pathogens like Pseudomonas aeruginosa, Acinetobacter spp., and multidrug-resistant (MDR) Enterobacteriaceae. These lessons need to be applied to our old drugs as well to preserve them and to be put into national and international antibiotic resistance strategies. As importantly, from a regulatory perspective, new chemical entities should have a resistance suppression plan at the time of regulatory review. In this way, we can make the best of our current situation and improve future prospects. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Evolutionary Origin of Antibiotic Resistance, A Historical Perspective

Directory of Open Access Journals (Sweden)

Yamile Adriana Celis Bustos

2017-07-01

Full Text Available Antimicrobial resistance is a natural aspect of bacterial evolution that can result from mutations or acquisition of foreign genes. Various views on the origin of this resistance explain the ability of these organisms to acquire new features. Lamarck andDarwin’s theories of evolution have led to experiments designed to explore the origin of bacterial variation and the emergence of new features. These experiments show that antimicrobial resistance is related to mutations in chromosomal genes and/or transfer of extrachromosomal genetic elements that can be expressed based on the antibiotic pressure exerted. The main experiments and findings that seek to explain the phenomenon of antibiotic resistance are reviewed here in.

correlations between antibiotic intake and resistance of some enteric ...

African Journals Online (AJOL)

DJFLEX

2010-06-25

Jun 25, 2010 ... Bacterial resistance to antibiotics has been attributed to many different factors with emphasis on the widespread use, misuse or overuse of antibiotics. Current thinking has referenced these as providing the selective pressure favouring propagation of resistant organisms (Livermore, 2003). This, however ...

Effects of biochar on reducing the abundance of oxytetracycline, antibiotic resistance genes, and human pathogenic bacteria in soil and lettuce.

Science.gov (United States)

Duan, Manli; Li, Haichao; Gu, Jie; Tuo, Xiaxia; Sun, Wei; Qian, Xun; Wang, Xiaojuan

2017-05-01

Antibiotics and antibiotic resistance genes (ARGs) in soil can affect human health via the food chain. Biochar is a soil amendment but its impacts on ARGs and the microbial communities associated with soil and vegetables are unclear. Therefore, we established three lettuce pot culture experiments, i.e., O300: 300 mg/kg oxytetracycline (OTC), BO300: 300 mg/kg OTC + 2% biochar, and a control without OTC or biochar. We found that under BO300, the relative abundances of ARGs were reduced by 51.8%, 43.4%, and 44.1% in lettuce leaves, roots, and soil, respectively, compared with O300. intI1 was highly abundant in soil and lettuce, and it co-occurred with some ARGs (tetW, ermF, and sul1). Redundancy analysis and network analysis indicated that the bacterial community succession was the main mechanism that affected the variations in ARGs and intI1. The reduction of Firmicutes due to the biochar treatment of soil and lettuce was the main factor responsible for the removal of tetracycline resistance genes in leaves. Biochar application led to the disappearance of human pathogenic bacteria (HPB), which was significantly correlated with the abundances of ermF and ermX. In summary, biochar is an effective farmland amendment for reducing the abundances of antibiotics, ARGs, and HPB in order to ensure the safety of vegetables and protect human health. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of antibiotic resistance patterns in collections of Escherichia coli and Proteus mirabilis uropathogenic strains.

Science.gov (United States)

Adamus-Bialek, Wioletta; Zajac, Elzbieta; Parniewski, Pawel; Kaca, Wieslaw

2013-04-01

Escherichia coli and Proteus mirabilis are important urinary tract pathogens. The constant increase in the antibiotic resistance of clinical bacterial strains has become an important clinical problem. The aim of this study was to compare the antibiotic resistance of 141 clinical (Sweden and Poland) and 42 laboratory (Czech Republic) P. mirabilis strains and 129 clinical (Poland) uropathogenic E. coli strains. The proportion of unique versus diverse patterns in Swedish clinical and laboratory P. mirabilis strain collections was comparable. Notably, a similar proportion of unique versus diverse patterns was observed in Polish clinical P. mirabilis and E. coli strain collections. Mathematical models of the antibiotic resistance of E. coli and P. mirabilis strains based on Kohonen networks and association analysis are presented. In contrast to the three clinical strain collections, which revealed complex associations with the antibiotics tested, laboratory P. mirabilis strains provided simple antibiotic association diagrams. The monitoring of antibiotic resistance patterns of clinical E. coli and P. mirabilis strains plays an important role in the treatment procedures for urinary tract infections and is important in the context of the spreading drug resistance in uropathogenic strain populations. The adaptability and flexibility of the genomes of E. coli and P. mirabilis strains are discussed.

Inhaled Antibiotics for Ventilator-Associated Infections.

Science.gov (United States)

Palmer, Lucy B

2017-09-01

Multidrug-resistant organisms are creating a challenge for physicians treating the critically ill. As new antibiotics lag behind the emergence of worsening resistance, intensivists in countries with high rates of extensively drug-resistant bacteria are turning to inhaled antibiotics as adjunctive therapy. These drugs can provide high concentrations of drug in the lung that could not be achieved with intravenous antibiotics without significant systemic toxicity. This article summarizes current evidence describing the use of inhaled antibiotics for the treatment of bacterial ventilator-associated pneumonia and ventilator-associated tracheobronchitis. Preliminary data suggest aerosolized antimicrobials may effectively treat resistant pathogens with high minimum inhibitory concentrations. Copyright © 2017 Elsevier Inc. All rights reserved.

Convergent acquisition of antibiotic resistance determinants ...

African Journals Online (AJOL)

Convergent acquisition of antibiotic resistance determinants amongst the Enterobacteriaceae isolates of the Mhlathuze River, KwaZulu-Natal (RSA) ... The possibility of transmission of resistant genes between bacteria (especially pathogenic) which invade human and animal populations within this river poses a health risk ...

In vitro activity of XF-73, a novel antibacterial agent, against antibiotic-sensitive and -resistant Gram-positive and Gram-negative bacterial species.

Science.gov (United States)

Farrell, David J; Robbins, Marion; Rhys-Williams, William; Love, William G

2010-06-01

The antibacterial activity of XF-73, a dicationic porphyrin drug, was investigated against a range of Gram-positive and Gram-negative bacteria with known antibiotic resistance profiles, including resistance to cell wall synthesis, protein synthesis, and DNA and RNA synthesis inhibitors as well as cell membrane-active antibiotics. Antibiotic-sensitive strains for each of the bacterial species tested were also included for comparison purposes. XF-73 was active [minimum inhibitory concentration (MIC) 0.25-4 mg/L] against all of the Gram-positive bacteria tested, irrespective of the antibiotic resistance profile of the isolates, suggesting that the mechanism of action of XF-73 is unique compared with the major antibiotic classes. Gram-negative activity was lower (MIC 1 mg/L to > 64 mg/L). Minimum bactericidal concentration data confirmed that the activity of XF-73 was bactericidal. Time-kill kinetics against healthcare-associated and community-associated meticillin-resistant Staphylococcus aureus isolates demonstrated that XF-73 was rapidly bactericidal, with > 5 log(10) kill obtained after 15 min at 2 x MIC, the earliest time point sampled. The post-antibiotic effect (PAE) for XF-73 under conditions where the PAE for vancomycin was 5.4 h. XF-73 represents a novel broad-spectrum Gram-positive antibacterial drug with potentially beneficial characteristics for the treatment and prevention of Gram-positive bacterial infections. 2010. Published by Elsevier B.V.

Pharmaceutical Approaches to Target Antibiotic Resistance Mechanisms.

Science.gov (United States)

Schillaci, Domenico; Spanò, Virginia; Parrino, Barbara; Carbone, Anna; Montalbano, Alessandra; Barraja, Paola; Diana, Patrizia; Cirrincione, Girolamo; Cascioferro, Stella

2017-10-26

There is urgent need for new therapeutic strategies to fight the global threat of antibiotic resistance. The focus of this Perspective is on chemical agents that target the most common mechanisms of antibiotic resistance such as enzymatic inactivation of antibiotics, changes in cell permeability, and induction/activation of efflux pumps. Here we assess the current landscape and challenges in the treatment of antibiotic resistance mechanisms at both bacterial cell and community levels. We also discuss the potential clinical application of chemical inhibitors of antibiotic resistance mechanisms as add-on treatments for serious drug-resistant infections. Enzymatic inhibitors, such as the derivatives of the β-lactamase inhibitor avibactam, are closer to the clinic than other molecules. For example, MK-7655, in combination with imipenem, is in clinical development for the treatment of infections caused by carbapenem-resistant Enterobacteriaceae and Pseudomonas aeruginosa, which are difficult to treat. In addition, other molecules targeting multidrug-resistance mechanisms, such as efflux pumps, are under development and hold promise for the treatment of multidrug resistant infections.

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.

A population model evaluating the consequences of the evolution of double-resistance and tradeoffs on the benefits of two-drug antibiotic treatments.

Science.gov (United States)

Campbell, Ellsworth M; Chao, Lin

2014-01-01

The evolution of antibiotic resistance in microbes poses one of the greatest challenges to the management of human health. Because addressing the problem experimentally has been difficult, research on strategies to slow the evolution of resistance through the rational use of antibiotics has resorted to mathematical and computational models. However, despite many advances, several questions remain unsettled. Here we present a population model for rational antibiotic usage by adding three key features that have been overlooked: 1) the maximization of the frequency of uninfected patients in the human population rather than the minimization of antibiotic resistance in the bacterial population, 2) the use of cocktails containing antibiotic pairs, and 3) the imposition of tradeoff constraints on bacterial resistance to multiple drugs. Because of tradeoffs, bacterial resistance does not evolve directionally and the system reaches an equilibrium state. When considering the equilibrium frequency of uninfected patients, both cycling and mixing improve upon single-drug treatment strategies. Mixing outperforms optimal cycling regimens. Cocktails further improve upon aforementioned strategies. Moreover, conditions that increase the population frequency of uninfected patients also increase the recovery rate of infected individual patients. Thus, a rational strategy does not necessarily result in a tragedy of the commons because benefits to the individual patient and general public are not in conflict. Our identification of cocktails as the best strategy when tradeoffs between multiple-resistance are operating could also be extended to other host-pathogen systems. Cocktails or other multiple-drug treatments are additionally attractive because they allow re-using antibiotics whose utility has been negated by the evolution of single resistance.

Diversity and Drug Resistance of Bacterial Pathogens Isolated from Bacterial Ascetic Disease in Cultured Turbot Scophthalmus maximus%养殖大菱鲆(Scophthalmus maximus)腹水病的病原多样性及其耐药性分析

Institute of Scientific and Technical Information of China (English)

王岚; 王印庚; 张正; 陈国华; 廖梅杰; 陈霞; 郭伟丽

2017-01-01

为了解引起养殖大菱鲆(Scophthalmus maximus)腹水病的病原多样性及其耐药性情况,针对2002-2010年由不同地区病样分离的27株细菌性病原进行了16S rDNA鉴定,并采用K-B法测定了27株细菌对22种抗生素的耐药性,分析了病原菌的耐药谱及耐药率变化.结果显示,大菱鲆腹水病病原菌主要有大菱鲆弧菌(Vibrio scophthalmi)、迟钝爱德华氏菌(Edwardsiella tarda)、鳗弧菌(Vibrio anguillarum)、哈维氏弧菌(Vibrio harveyi)、假交替单胞菌(Pseudoalteromonas espejiana).山东青岛地区以大菱鲆弧菌为主,威海地区以迟钝爱德华氏菌为主,烟台地区菌株种类分布平均.5类细菌对青霉素类、头孢菌素类、大环内酯类、复方新诺明耐药率高于50％.只有1株迟钝爱德华氏菌对氟苯尼考产生了耐药,其余菌株对其均没有耐药性,且在长期使用中不易产生耐药性,证实氟苯尼考为当前防治腹水病的一种良好抗菌药物.27株病原菌的耐药谱数量为27个,每个菌株具备自己独特的耐药谱,74.1％的菌株对10种以上的抗菌药物产生了耐药性,均有多重耐药性.%Turbot Scophthalmus maximus was introduced into China in 1992.Since then,it has become one of the most dominant mariculture industries.In recent years,however,a main bottleneck constraining its commercial development is the disease problem prevailing in the farms and causing significant mortalities.Ascites syndrome is a disease that is commonly found in larvae culture and grow-out period.The present study investigated the diversity and antimicrobial resistance of the pathogens isolated from bacterial ascetic disease in cultured turbot S.maximus in Shandong Province.In total,27 bacterial pathogens were collected from different regions of the province between 2002 and 2010.These 27 strains of pathogens were identified through the use of 16S rDNA gene sequence analysis and their antibiotic resistance profiles were tested with 22

Carriage of antibiotic-resistant enteric bacteria varies among sites in Galapagos reptiles.

Science.gov (United States)

Wheeler, Emily; Hong, Pei-Ying; Bedon, Lenin Cruz; Mackie, Roderick I

2012-01-01

Increased overlap between humans and wildlife populations has increased the risk for novel disease emergence. Detecting contacts with a high risk for transmission of pathogens requires the identification of dependable measures of microbial exchange. We evaluated antibiotic resistance as a molecular marker for the intensity of human-wildlife microbial connectivity in the Galápagos Islands. We isolated Escherichia coli and Salmonella enterica from the feces of land iguanas (Conolophus sp.), marine iguanas (Amblyrhynchus cristatus), giant tortoises (Geochelone nigra), and seawater, and tested these bacteria with the use of the disk diffusion method for resistance to 10 antibiotics. Antibiotic-resistant bacteria were found in reptile feces from two tourism sites (Isla Plaza Sur and La Galapaguera on Isla San Cristóbal) and from seawater close to a public use beach near Puerto Baquerizo Moreno on Isla San Cristóbal. No resistance was detected at two protected beaches on more isolated islands (El Miedo on Isla Santa Fe and Cape Douglas on Isla Fernandina) and at a coastal tourism site (La Lobería on Isla San Cristóbal). Eighteen E. coli isolates from three locations, all sites relatively proximate to a port town, were resistant to ampicillin, doxycycline, tetracycline, and trimethoprin/sulfamethoxazole. In contrast, only five S. enterica isolates showed a mild decrease in susceptibility to doxycycline and tetracycline from these same sites (i.e., an intermediate resistance phenotype), but no clinical resistance was detected in this bacterial species. These findings suggest that reptiles living in closer proximity to humans potentially have higher exposure to bacteria of human origin; however, it is not clear from this study to what extent this potential exposure translates to ongoing exchange of bacterial strains or genetic traits. Resistance patterns and bacterial exchange in this system warrant further investigation to understand better how human associations

Microfluidic system for the identification of bacterial pathogens causing urinary tract infections

Science.gov (United States)

Becker, Holger; Hlawatsch, Nadine; Haraldsson, Tommy; van der Wijngaart, Wouter; Lind, Anders; Malhotra-Kumar, Surbi; Turlej-Rogacka, Agata; Goossens, Herman

2015-03-01

Urinary tract infections (UTIs) are among the most common bacterial infections and pose a significant healthcare burden. The growing trend in antibiotic resistance makes it mandatory to develop diagnostic kits which allow not only the determination of a pathogen but also the antibiotic resistances. We have developed a microfluidic cartridge which takes a direct urine sample, extracts the DNA, performs an amplification using batch-PCR and flows the sample over a microarray which is printed into a microchannel for fluorescence detection. The cartridge is injection-molded out of COP and contains a set of two-component injection-molded rotary valves to switch between input and to isolate the PCR chamber during thermocycling. The hybridization probes were spotted directly onto a functionalized section of the outlet microchannel. We have been able to successfully perform PCR of E.coli in urine in this chip and perform a fluorescence detection of PCR products. An upgraded design of the cartridge contains the buffers and reagents in blisters stored on the chip.

[Arms racing between human beings and pathogens: NDM-1 and superbugs].

Science.gov (United States)

Sun, Mingwei; Zheng, Beiwen; Gao, George F; Zhu, Baoli

2010-11-01

Throughout human history, pandemic bacterial diseases such as the plague and tuberculosis have posed an enormous threat to human beings. The discovery of antibiotics has provided us with powerful arsenal for the defense against bacterial infections. However, bacteria are acquiring more and more resistance genes to shield off antibiotics through mutation and horizontal gene transfer. Therefore, novel antibiotics must be produced and the arms race between bacterial pathogens and antibiotics is becoming increasingly intense. Recently, researchers have found that plasmids carrying a new metallo-beta-lactamase gene, blaNDM-1, and many other antibiotics resistance genes can easily spread through bacterial populations and confer recipient stains resistance to nearly all of the current antibiotics. It is a threat to the human health and a great challenge for our medical science, which we are facing. We need to find new ways to fight and win this arms racing.

Prevalence and Antibiotic Resistance of Gram-Negative Pathogenic Bacteria Species Isolated from Periplaneta americana and Blattella germanica in Varanasi, India.

Directory of Open Access Journals (Sweden)

D Leshan Wannigama

2014-06-01

Full Text Available Cockroaches are among the medically important pests found within the human habitations that cause serious public health problems. They may harbor a number of pathogenic bacteria on the external surface with antibiotic resistance. Hence, they are regarded as major microbial vectors. This study investigates the prevalence and antibiotic resistance of Gram-negative pathogenic bacteria species isolated from Periplaneta americana and Blattella germanica in Varanasi, India.Totally, 203 adult cockroaches were collected form 44 households and 52 food-handling establishments by trapping. Bacteriological examination of external surfaces of Pe. americana and Bl. germanica were carried out using standard method and antibiotics susceptibility profiles of the isolates were determined using Kirby-Bauer disc diffusion methods.Among the places, we found that 54% had cockroache infestation in households and 77% in food- handling establishments. There was no significant different between the overall bacteria load of the external surface in Pe. americana (64.04% and Bl. germanica (35.96%. However the predominant bacteria on cockroaches were Klebsiella pneumonia, Escherichia coli, Enterobacter aerogenes, and Pseudomonas aeruginosa. However, Kl. pneumoniae and Ps. aeruginosa were the most prevalent, drug-resistant strains were isolated from the cockroaches with 100% resistance to sulfamethoxazole/trimethoprim and ampicillin. For individual strains of bacteria, Escherichia coli was found to have multi-resistance to four antibiotic tested, Citrobacter freundii four, Enterobacter aerogenes and Proteus mirabilis to three.Cockroaches are uniformly distributed in domestic environment, which can be a possible vector for transmission of drug-resistant bacteria and food-borne diseases.

Microbiological and biochemical studies on certain antibiotic-resistant bacteria isolated from certain clinical specimens

Energy Technology Data Exchange (ETDEWEB)

Nada, H M.AL.M. [National Center for Radiation Research and Technology, Atomic Energy Authority, Cairo (Egypt)

2008-07-01

Infection is a dynamic process involving invasion of the body by pathogenic microorganisms and reactions of the tissues to microorganisms and their toxins. Pathogenic microorganisms isolated from clinical samples are of great threat to human health.The outcome of an infection depends on the virulence of the pathogen and the relative degree of resistance or susceptibility to antimicrobial chemotherapy. Antimicrobial agents interfere with specific processes that are essential for growth and division.Development of antibiotic resistance in bacteria is a problem of great concern. The high prevalence of resistant bacteria seems to be related to uncontrolled usage of antibiotics. B-lactamases are the most common cause of bacterial resistance to B-lactam antimicrobial agents, and it is one of the most important reason for increasing the resistance in pathogenic bacteria against some antibiotics especially those acting on inhibition of cell wall synthesis. One hundred and seven clinical samples and specimens were collected from public, private hospitals and National Cancer Institute (NCI) in Cairo, Egypt. Out of them 72 cases positive for microbial infection. Twelve cases were showed mixed infection. Eighty four isolates of pathogenic bacteria and yeast were collected from single and mixed culture. Susceptibilities of the isolates to 20 different antimicrobial agents were determined according to Kirby-Bauer method. Nine multi-drug resistant gram-negative bacterial strains were identified by (Micro Scan WalkAway 96 SI System). Six of them urine isolates, 2 wound (pus) isolates and one sputum isolate. The identified strains were exposed to in-vitro gamma irradiation at dose level of 24.4 Gy, which is biologically equivalent to the fractionated multiple therapeutic dose used in the protocol of cancer treatment of some patients. The antimicrobial susceptibility of the nine multi-drug resistant strains were carried out by disk diffusion method before and after irradiation

Microbiological and biochemical studies on certain antibiotic-resistant bacteria isolated from certain clinical specimens

International Nuclear Information System (INIS)

Nada, H.M.AL.M.

2008-01-01

Infection is a dynamic process involving invasion of the body by pathogenic microorganisms and reactions of the tissues to microorganisms and their toxins. Pathogenic microorganisms isolated from clinical samples are of great threat to human health.The outcome of an infection depends on the virulence of the pathogen and the relative degree of resistance or susceptibility to antimicrobial chemotherapy. Antimicrobial agents interfere with specific processes that are essential for growth and division.Development of antibiotic resistance in bacteria is a problem of great concern. The high prevalence of resistant bacteria seems to be related to uncontrolled usage of antibiotics. B-lactamases are the most common cause of bacterial resistance to B-lactam antimicrobial agents, and it is one of the most important reason for increasing the resistance in pathogenic bacteria against some antibiotics especially those acting on inhibition of cell wall synthesis. One hundred and seven clinical samples and specimens were collected from public, private hospitals and National Cancer Institute (NCI) in Cairo, Egypt. Out of them 72 cases positive for microbial infection. Twelve cases were showed mixed infection. Eighty four isolates of pathogenic bacteria and yeast were collected from single and mixed culture. Susceptibilities of the isolates to 20 different antimicrobial agents were determined according to Kirby-Bauer method. Nine multi-drug resistant gram-negative bacterial strains were identified by (Micro Scan WalkAway 96 SI System). Six of them urine isolates, 2 wound (pus) isolates and one sputum isolate. The identified strains were exposed to in-vitro gamma irradiation at dose level of 24.4 Gy, which is biologically equivalent to the fractionated multiple therapeutic dose used in the protocol of cancer treatment of some patients. The antimicrobial susceptibility of the nine multi-drug resistant strains were carried out by disk diffusion method before and after irradiation

Challenges and Future Prospects of Antibiotic Therapy: From Peptides to Phages Utilization

Directory of Open Access Journals (Sweden)

Santi M. Mandal

2014-05-01

Full Text Available Bacterial infections are raising serious concern across the globe. The effectiveness of conventional antibiotics is decreasing due to global emergence of multi-drug-resistant (MDR bacterial pathogens. This process seems to be primarily caused by an indiscriminate and inappropriate use of antibiotics in non-infected patients and in the food industry. New classes of antibiotics with different actions against MDR pathogens need to be developed urgently. In this context, this review focuses on several ways and future directions to search for the next generation of safe and effective antibiotics compounds including antimicrobial peptides, phage therapy, phytochemicals, metalloantibiotics, LPS and efflux pump inhibitors to control the infections caused by MDR pathogens.

Mechanisms of antibiotic resistance in Staphylococcus aureus.

Science.gov (United States)

Pantosti, Annalisa; Sanchini, Andrea; Monaco, Monica

2007-06-01

Staphylococcus aureus can exemplify better than any other human pathogen the adaptive evolution of bacteria in the antibiotic era, as it has demonstrated a unique ability to quickly respond to each new antibiotic with the development of a resistance mechanism, starting with penicillin and methicillin, until the most recent, linezolid and daptomycin. Resistance mechanisms include enzymatic inactivation of the antibiotic (penicillinase and aminoglycoside-modification enzymes), alteration of the target with decreased affinity for the antibiotic (notable examples being penicillin-binding protein 2a of methicillin-resistant S. aureus and D-Ala-D-Lac of peptidoglycan precursors of vancomycin-resistant strains), trapping of the antibiotic (for vancomycin and possibly daptomycin) and efflux pumps (fluoroquinolones and tetracycline). Complex genetic arrays (staphylococcal chromosomal cassette mec elements or the vanA operon) have been acquired by S. aureus through horizontal gene transfer, while resistance to other antibiotics, including some of the most recent ones (e.g., fluoroquinolones, linezolid and daptomycin) have developed through spontaneous mutations and positive selection. Detection of the resistance mechanisms and their genetic basis is an important support to antibiotic susceptibility surveillance in S. aureus.

Removal of micropollutants, facultative pathogenic and antibiotic resistant bacteria in a full-scale retention soil filter receiving combined sewer overflow.

Science.gov (United States)

Scheurer, Marco; Heß, Stefanie; Lüddeke, Frauke; Sacher, Frank; Güde, Hans; Löffler, Herbert; Gallert, Claudia

2015-01-01

Combined sewer systems collect surface runoff as well as wastewater of industrial and domestic origin. During periods of heavy rainfall the capacity of the sewer system is exceeded and the overflow is discharged into receiving waters without any treatment. Consequently, combined sewer overflow (CSO) is considered as a major source of water pollution. This study investigates the effectiveness of a retention soil filter (RSF) for the removal of micropollutants as well as facultative pathogenic and antibiotic resistant bacteria from CSO. The removal of organic group parameters like total organic carbon was excellent and the removal efficiency for micropollutants of the RSF and the wastewater treatment plant (WWTP), which treats wastewater of the same origin during dry and normal weather conditions, was comparable. Compounds of high environmental concern like estrogens or certain pharmaceuticals, e.g. diclofenac, were completely eliminated or removed to a high degree during RSF passage. RSF treatment also reduced the number of E. coli, enterococci and staphylococci by 2.7, 2.2 and 2.4 log-units (median values), respectively. Obviously, some Staphylococcus species can better adapt to the conditions of the RSF than others as a shift of the abundance of the different species was observed when comparing the diversity of staphylococci obtained from the RSF influent and effluent. RSF treatment also decreased the absolute number of antibiotic resistant bacteria. The percentage of antibiotic resistant E. coli and staphylococci isolates also decreased during passage of the RSF, whereas the percentage of resistant enterococci did not change. For E. coli ampicillin and for enterococci and staphylococci erythromycin determined the antibiotic resistance level. The results demonstrate that RSFs can be considered as an adequate treatment option for CSO. The performance for the removal of micropollutants is comparable with a medium sized WWTP with conventional activated sludge

Detection of antibiotic resistance in probiotics of dietary supplements

KAUST Repository

Wong, Aloysius Tze

2015-09-14

Background Probiotics are live microorganisms that confer nutrition- and health-promoting benefits if consumed in adequate amounts. Concomitant with the demand for natural approaches to maintaining health is an increase in inclusion of probiotics in food and health products. Since probiotic bacteria act as reservoir for antibiotic resistant determinants, the transfer of these genes to pathogens sharing the same intestinal habitat is thus conceivable considering the fact that dietary supplements contain high amounts of often heterogeneous populations of probiotics. Such events can confer pathogens protection against commonly-used drugs. Despite numerous reports of antibiotic resistant probiotics in food and biological sources, the antibiogram of probiotics from dietary supplements remained elusive. Findings Here, we screened five commercially available dietary supplements for resistance towards antibiotics of different classes. Probiotics of all batches of products were resistant towards vancomycin while batch-dependent resistance towards streptomycin, aztreonam, gentamycin and/or ciprofloxacin antibiotics was detected for probiotics of brands Bi and Bn, Bg, and L. Isolates of brand Cn was also resistant towards gentamycin, streptomycin and ciprofloxacin antibiotics. Additionally, we also report a discrepancy between the enumerated viable bacteria amounts and the claims of the manufacturers. Conclusions This short report has highlighted the present of antibiotic resistance in probiotic bacteria from dietary supplements and therefore serves as a platform for further screenings and for in-depth characterization of the resistant determinants and the molecular machinery that confers the resistance.

Occurrence and Distribution of Antibiotic-resistant Bacteria and Transfer of Resistance Genes in Lake Taihu

OpenAIRE

Yin, Qian; Yue, Dongmei; Peng, Yuke; Liu, Ying; Xiao, Lin

2013-01-01

The overuse of antibiotics has accelerated antibiotic resistance in the natural environment, especially fresh water, generating a potential risk for public health around the world. In this study, antibiotic resistance in Lake Taihu was investigated and this was the first thorough data obtained through culture-dependent methods. High percentages of resistance to streptomycin and ampicillin among bacterial isolates were detected, followed by tetracycline and chloramphenicol. Especially high lev...

How Nature Morphs Peptide Scaffolds into Antibiotics

Science.gov (United States)

Nolan, Elizabeth M.; Walsh, Christopher T.

2010-01-01

The conventional notion that peptides are poor candidates for orally available drugs because of protease-sensitive peptide bonds, intrinsic hydrophilicity, and ionic charges contrasts with the diversity of antibiotic natural products with peptide-based frameworks that are synthesized and utilized by Nature. Several of these antibiotics, including penicillin and vancomycin, are employed to treat bacterial infections in humans and have been best-selling therapeutics for decades. Others might provide new platforms for the design of novel therapeutics to combat emerging antibiotic-resistant bacterial pathogens. PMID:19058272

Biofilm processes in treating mariculture wastewater may be a reservoir of antibiotic resistance genes

International Nuclear Information System (INIS)

Li, Shuai; Zhang, Shenghua; Ye, Chengsong; Lin, Wenfang; Zhang, Menglu; Chen, Lihua; Li, Jinmei; Yu, Xin

2017-01-01

Antibiotics are heavily used in Chinese mariculture, but only a small portion of the added antibiotics are absorbed by living creatures. Biofilm processes are universally used in mariculture wastewater treatment. In this study, removal of antibiotics (norfloxacin, rifampicin, and oxytetracycline) from wastewater by moving bed biofilm reactors (MBBRs) and the influence of antibiotics on reactor biofilm were investigated. The results demonstrated that there was no significant effect of sub-μg/L–sub-mg/L concentrations of antibiotics on TOC removal. Moreover, the relative abundance of antibiotic resistance genes (ARGs) and antibiotic resistance bacteria (ARB) in MBBR biofilm increased because of selective pressure of antibiotics. In addition, antibiotics decreased the diversity of the biofilm bacterial community and altered bacterial community structure. These findings provide an empirical basis for the development of appropriate practices for mariculture, and suggest that disinfection and advanced oxidation should be applied to eliminate antibiotics, ARGs, and ARB from mariculture wastewater. - Highlights: • The removal of antibiotics by Moving Bed Biofilm Reactors (MBBR) was investigated. • Biofilm process such as MBBR had little effect on the removal of the antibiotics. • The antibiotics decreased the diversity of biofilm bacterial community and altered bacterial community structure. • Biofilm processes in treating mariculture wastewater may be a reservoir of antibiotic resistance genes.

Direct mass spectrometric screening of antibiotics from bacterial surfaces using liquid extraction surface analysis.

Science.gov (United States)

Kai, Marco; González, Ignacio; Genilloud, Olga; Singh, Sheo B; Svatoš, Aleš

2012-10-30

There is a need to find new antibiotic agents to fight resistant pathogenic bacteria. To search successfully for novel antibiotics from bacteria cultivated under diverse conditions, we need a fast and cost-effective screening method. A combination of Liquid Extraction Surface Analysis (LESA), automated chip-based nanoelectrospray ionization, and high-resolution mass or tandem mass spectrometry using an Orbitrap XL was tested as the screening platform. Actinobacteria, known to produce well-recognized thiazolyl peptide antibiotics, were cultivated on a plate of solid medium and the antibiotics were extracted by organic solvent mixtures from the surface of colonies grown on the plate and analyzed using mass spectrometry (MS). LESA combined with high-resolution MS is a powerful tool with which to extract and detect thiazolyl peptide antibiotics from different Actinobacteria. Known antibiotics were correctly detected with high mass accuracy (antibiotics in particular and natural products in general. The method described in this paper is suitable for (1) screening the natural products produced by bacterial colonies on cultivation plates within the first 2 min following extraction and (2) detecting antibiotics at high mass accuracy; the cost is around 2 Euro per sample. Copyright © 2012 John Wiley & Sons, Ltd.

Novel bacterial metabolite merochlorin A demonstrates in vitro activity against multi-drug resistant methicillin-resistant Staphylococcus aureus.

Directory of Open Access Journals (Sweden)

George Sakoulas

Full Text Available We evaluated the in vitro activity of a merochlorin A, a novel compound with a unique carbon skeleton, against a spectrum of clinically relevant bacterial pathogens and against previously characterized clinical and laboratory Staphylococcus aureus isolates with resistance to numerous antibiotics.Merochlorin A was isolated and purified from a marine-derived actinomycete strain CNH189. Susceptibility testing for merochlorin A was performed against previously characterized human pathogens using broth microdilution and agar dilution methods. Cytotoxicity was assayed in tissue culture assays at 24 and 72 hours against human HeLa and mouse sarcoma L929 cell lines.The structure of as new antibiotic, merochlorin A, was assigned by comprehensive spectroscopic analysis. Merochlorin A demonstrated in vitro activity against Gram-positive bacteria, including Clostridium dificile, but not against Gram negative bacteria. In S. aureus, susceptibility was not affected by ribosomal mutations conferring linezolid resistance, mutations in dlt or mprF conferring resistance to daptomycin, accessory gene regulator knockout mutations, or the development of the vancomycin-intermediate resistant phenotype. Merochlorin A demonstrated rapid bactericidal activity against MRSA. Activity was lost in the presence of 20% serum.The unique meroterpenoid, merochlorin A demonstrated excellent in vitro activity against S. aureus and C. dificile and did not show cross-resistance to contemporary antibiotics against Gram positive organisms. The activity was, however, markedly reduced in 20% human serum. Future directions for this compound may include evaluation for topical use, coating biomedical devices, or the pursuit of chemically modified derivatives of this compound that retain activity in the presence of serum.

Therapeutic Potential of a Scorpion Venom-Derived Antimicrobial Peptide and Its Homologs Against Antibiotic-Resistant Gram-Positive Bacteria

Directory of Open Access Journals (Sweden)

Gaomin Liu

2018-05-01

Full Text Available The alarming rise in the prevalence of antibiotic resistance among pathogenic bacteria poses a unique challenge for the development of effective therapeutic agents. Antimicrobial peptides (AMPs have attracted a great deal of attention as a possible solution to the increasing problem of antibiotic-resistant bacteria. Marcin-18 was identified from the scorpion Mesobuthus martensii at both DNA and protein levels. The genomic sequence revealed that the marcin-18 coding gene contains a phase-I intron with a GT-AG splice junction located in the DNA region encoding the N-terminal part of signal peptide. The peptide marcin-18 was also isolated from scorpion venom. A protein sequence homology search revealed that marcin-18 shares extremely high sequence identity to the AMPs meucin-18 and megicin-18. In vitro, chemically synthetic marcin-18 and its homologs (meucin-18 and megicin-18 showed highly potent inhibitory activity against Gram-positive bacteria, including some clinical antibiotic-resistant strains. Importantly, in a mouse acute peritonitis model, these peptides significantly decreased the bacterial load in ascites and rescued nearly all mice heavily infected with clinical methicillin-resistant Staphylococcus aureus from lethal bacteremia. Peptides exerted antimicrobial activity via a bactericidal mechanism and killed bacteria through membrane disruption. Taken together, marcin-18 and its homologs have potential for development as therapeutic agents for treating antibiotic-resistant, Gram-positive bacterial infections.

Molecular study on some antibiotic resistant genes in Salmonella spp. isolates