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Sample records for resistant bacteria ccnwrs33-2

  1. Antibiotic-Resistant Bacteria.

    ERIC Educational Resources Information Center

    Longenecker, Nevin E.; Oppenheimer, Dan

    1982-01-01

    A study conducted by high school advanced bacteriology students appears to confirm the hypothesis that the incremental administration of antibiotics on several species of bacteria (Escherichia coli, Staphylococcus epidermis, Bacillus sublitus, Bacillus megaterium) will allow for the development of antibiotic-resistant strains. (PEB)

  2. Antibiotic-Resistant Bacteria.

    ERIC Educational Resources Information Center

    Longenecker, Nevin E.; Oppenheimer, Dan

    1982-01-01

    A study conducted by high school advanced bacteriology students appears to confirm the hypothesis that the incremental administration of antibiotics on several species of bacteria (Escherichia coli, Staphylococcus epidermis, Bacillus sublitus, Bacillus megaterium) will allow for the development of antibiotic-resistant strains. (PEB)

  3. [Nosocomial bacteria: profiles of resistance].

    PubMed

    Sow, A I

    2005-01-01

    Nosocomial infections may be parasitic, mycosal or viral, but bacterial infections are more frequent. They are transmitted by hands or by oral route. This paper describes the main bacteria responsive of nosocomial infections, dominated by Staphylococcus, enterobacteria and Pseudomonas aeruginosa. The author relates natural and savage profiles of these bacterias, characterized by multiresistance due to large use of antibiotics. Knowledge of natural resistance and verification of aquired resistance permit to well lead probabilist antibiotherapy.

  4. The intrinsic resistance of bacteria.

    PubMed

    Gang, Zhang; Jie, Feng

    2016-10-20

    Antibiotic resistance is often considered to be a trait acquired by previously susceptible bacteria, on the basis of which can be attributed to the horizontal acquisition of new genes or the occurrence of spontaneous mutation. In addition to acquired resistance, bacteria have a trait of intrinsic resistance to different classes of antibiotics. An intrinsic resistance gene is involved in intrinsic resistance, and its presence in bacterial strains is independent of previous antibiotic exposure and is not caused by horizontal gene transfer. Recently, interest in intrinsic resistance genes has increased, because these gene products not only may provide attractive therapeutic targets for development of novel drugs that rejuvenate the activity of existing antibiotics, and but also might predict future emergence of resistant pathogens if they become mobilized. In the present review, we summarize the conventional examples of intrinsic resistance, including the impermeability of cellular envelopes, the activity of multidrug efflux pumps or lack of drug targets. We also demonstrate that transferases and enzymes involved in basic bacterial metabolic processes confer intrinsic resistance in Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. We present as well information on the cryptic intrinsic resistance genes that do not confer resistance to their native hosts but are capable of conferring resistance when their expression levels are increased and the activation of the cryptic genes. Finally, we discuss that intrinsic genes could be the origin of acquired resistance, especially in the genus Acinetobacter.

  5. Antibiotic resistance in probiotic bacteria

    PubMed Central

    Gueimonde, Miguel; Sánchez, Borja; G. de los Reyes-Gavilán, Clara; Margolles, Abelardo

    2013-01-01

    Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. The main probiotic bacteria are strains belonging to the genera Lactobacillus and Bifidobacterium, although other representatives, such as Bacillus or Escherichia coli strains, have also been used. Lactobacillus and Bifidobacterium are two common inhabitants of the human intestinal microbiota. Also, some species are used in food fermentation processes as starters, or as adjunct cultures in the food industry. With some exceptions, antibiotic resistance in these beneficial microbes does not constitute a safety concern in itself, when mutations or intrinsic resistance mechanisms are responsible for the resistance phenotype. In fact, some probiotic strains with intrinsic antibiotic resistance could be useful for restoring the gut microbiota after antibiotic treatment. However, specific antibiotic resistance determinants carried on mobile genetic elements, such as tetracycline resistance genes, are often detected in the typical probiotic genera, and constitute a reservoir of resistance for potential food or gut pathogens, thus representing a serious safety issue. PMID:23882264

  6. Cadmium uptake and resistance among selected bacteria

    SciTech Connect

    Burke, B.E.

    1987-01-01

    The purpose of this research was to determine the relationship between Cd resistance and Cd uptake by lake sediment bacteria. For the Gram positive and gram negative sediment bacteria that were tested, the relationship between resistance and Cd uptake varied and was dependent on the isolate under consideration. Results of this study indicated that bacterial communities in lake sediments may influence the concentration and availability of Cd in sediments and the water column. In addition, results of this study did not support the theory that the genes encoding for Cd resistance are usually carried on antibiotic resistance plasmids.

  7. Mechanisms of polymyxin resistance: acquired and intrinsic resistance in bacteria

    PubMed Central

    Olaitan, Abiola O.; Morand, Serge; Rolain, Jean-Marc

    2014-01-01

    Polymyxins are polycationic antimicrobial peptides that are currently the last-resort antibiotics for the treatment of multidrug-resistant, Gram-negative bacterial infections. The reintroduction of polymyxins for antimicrobial therapy has been followed by an increase in reports of resistance among Gram-negative bacteria. Some bacteria, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, develop resistance to polymyxins in a process referred to as acquired resistance, whereas other bacteria, such as Proteus spp., Serratia spp., and Burkholderia spp., are naturally resistant to these drugs. Reports of polymyxin resistance in clinical isolates have recently increased, including acquired and intrinsically resistant pathogens. This increase is considered a serious issue, prompting concern due to the low number of currently available effective antibiotics. This review summarizes current knowledge concerning the different strategies bacteria employ to resist the activities of polymyxins. Gram-negative bacteria employ several strategies to protect themselves from polymyxin antibiotics (polymyxin B and colistin), including a variety of lipopolysaccharide (LPS) modifications, such as modifications of lipid A with phosphoethanolamine and 4-amino-4-deoxy-L-arabinose, in addition to the use of efflux pumps, the formation of capsules and overexpression of the outer membrane protein OprH, which are all effectively regulated at the molecular level. The increased understanding of these mechanisms is extremely vital and timely to facilitate studies of antimicrobial peptides and find new potential drugs targeting clinically relevant Gram-negative bacteria. PMID:25505462

  8. Evolution of Drug Resistance in Bacteria.

    PubMed

    Waclaw, B

    2016-01-01

    Resistance to antibiotics is an important and timely problem of contemporary medicine. Rapid evolution of resistant bacteria calls for new preventive measures to slow down this process, and a longer-term progress cannot be achieved without a good understanding of the mechanisms through which drug resistance is acquired and spreads in microbial populations. Here, we discuss recent experimental and theoretical advances in our knowledge how the dynamics of microbial populations affects the evolution of antibiotic resistance . We focus on the role of spatial and temporal drug gradients and show that in certain situations bacteria can evolve de novo resistance within hours. We identify factors that lead to such rapid onset of resistance and discuss their relevance for bacterial infections.

  9. Antibiotic resistance among autochthonous aquatic environmental bacteria.

    PubMed

    Schreiber, Christiane; Kistemann, Thomas

    2013-01-01

    Antibiotics are widely used in both human and veterinary medicine and antibiotic-resistant bacteria cause problems in antibiotic therapy. The current study was conducted in the catchment area of the river Swist (Germany) and focuses on the resistance of environmental Rhodospirillaceae to antibiotics used in human medicine. The samples collected reflect different levels of human impact on the environment. In total, 614 isolates were tested for antibiotic susceptibility. About half of these isolates were susceptible to all substances tested. Oxacillin resistance was observed most frequently (41%). Resistant Rhodospirillaceae were detected in wastewater effluent from a municipal sewage treatment plant, as well as in non-polluted upper reaches. The highest multi-resistance level was detected in small tributaries and it surprisingly decreased with an increasing influence of municipal wastewater. It could be shown that the detected resistances were acquired rather than intrinsic. Besides natural occurrence of multi-resistance among non-sulphur purple bacteria, horizontal gene transfer and acquired cross-resistance against veterinary antibiotics are assumed to be important factors. To the authors' knowledge, this is the first study investigating the potential of Rhodospirillaceae as a reservoir for resistance to antibiotics used in human medicine. The consequence for resistance prevalence in human pathogens and for their antibiotic therapy needs evaluation.

  10. Bacteriophage biosensors for antibiotic-resistant bacteria.

    PubMed

    Sorokulova, Irina; Olsen, Eric; Vodyanoy, Vitaly

    2014-03-01

    An increasing number of disease-causing bacteria are resistant to one or more anti-bacterial drugs utilized for therapy. Early and speedy detection of these pathogens is therefore very important. Traditional pathogen detection techniques, that include microbiological and biochemical assays are long and labor-intensive, while antibody or DNA-based methods require substantial sample preparation and purification. Biosensors based on bacteriophages have demonstrated remarkable potential to surmount these restrictions and to offer rapid, efficient and sensitive detection technique for antibiotic-resistant bacteria.

  11. Beer spoilage bacteria and hop resistance.

    PubMed

    Sakamoto, Kanta; Konings, Wil N

    2003-12-31

    For brewing industry, beer spoilage bacteria have been problematic for centuries. They include some lactic acid bacteria such as Lactobacillus brevis, Lactobacillus lindneri and Pediococcus damnosus, and some Gram-negative bacteria such as Pectinatus cerevisiiphilus, Pectinatus frisingensis and Megasphaera cerevisiae. They can spoil beer by turbidity, acidity and the production of unfavorable smell such as diacetyl or hydrogen sulfide. For the microbiological control, many advanced biotechnological techniques such as immunoassay and polymerase chain reaction (PCR) have been applied in place of the conventional and time-consuming method of incubation on culture media. Subsequently, a method is needed to determine whether the detected bacterium is capable of growing in beer or not. In lactic acid bacteria, hop resistance is crucial for their ability to grow in beer. Hop compounds, mainly iso-alpha-acids in beer, have antibacterial activity against Gram-positive bacteria. They act as ionophores which dissipate the pH gradient across the cytoplasmic membrane and reduce the proton motive force (pmf). Consequently, the pmf-dependent nutrient uptake is hampered, resulting in cell death. The hop-resistance mechanisms in lactic acid bacteria have been investigated. HorA was found to excrete hop compounds in an ATP-dependent manner from the cell membrane to outer medium. Additionally, increased proton pumping by the membrane bound H(+)-ATPase contributes to hop resistance. To energize such ATP-dependent transporters hop-resistant cells contain larger ATP pools than hop-sensitive cells. Furthermore, a pmf-dependent hop transporter was recently presented. Understanding the hop-resistance mechanisms has enabled the development of rapid methods to discriminate beer spoilage strains from nonspoilers. The horA-PCR method has been applied for bacterial control in breweries. Also, a discrimination method was developed based on ATP pool measurement in lactobacillus cells. However

  12. Antimicrobial resistance in bacteria from horses: Epidemiology of antimicrobial resistance.

    PubMed

    Maddox, T W; Clegg, P D; Williams, N J; Pinchbeck, G L

    2015-11-01

    Antimicrobial resistance poses a significant threat to the continued successful use of antimicrobial agents for the treatment of bacterial infections. While the epidemiology of antimicrobial resistance in bacteria from man has been studied extensively, less work has been undertaken in companion animals, particularly horses. Methicillin-resistant Staphylococcus aureus has been identified as a cause of infections, with a low prevalence of nasal carriage by horses in the community but higher for hospitalised horses. Molecular characterisation has shown methicillin-resistant Staphylococcus aureus strains either to be predominantly of types associated with horses or of sequence type ST398. Antimicrobial-resistant Escherichia coli (including multidrug-resistant and extended spectrum β-lactamase-producing isolates) have caused infections and been documented in faecal carriage by horses, with many significant resistance mechanisms identified. More sporadic reports and molecular characterisation exist for resistance in other bacteria such as enterococci, Salmonella, Acinetobacter and Pseudomonas species. Limited work has been undertaken evaluating risk factors and much of the epidemiology of antimicrobial resistance in bacteria from horses remains to be determined.

  13. Detection of sulfonamide resistant bacteria and resistance genes in soils

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Zhang, Weiyu; Liu, Huifen; Wang, Xiaobo; Yang, Fan; Zeng, Ming; Chen, Pinpin; Wang, Xiao

    2017-04-01

    Manure application could accelerate the environmental dissemination of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in soils. In this study, the prevalence of sulfonamide resistant bacteria and resistance genes was investigated in agricultural soils to which organic manures had been applied in Tianjin, China. Anti-sulfonamide bacteria were found in the range of 3.29 × 104 to 1.70 × 105 CFU/g dry soil, occupying 1.5% to 2.2% of total viable counts. And sulI and sulII genes were detected in all sampling sites, with relative abundances of 5.69 × 10-5 to 6.95 × 10-4 and 4.28 × 10-4 to 1.25 × 10-3 respectively. No significant correlations between cultivable sulfonamide resistant bacteria and sul genes were found in this study. While sulI showed significant positive correlation with soil organic matter. Overall, the results highlight that soil plays an important role in resistance genes capture as the environmental reservoir.

  14. Surgical patients with multiantibiotic-resistant bacteria.

    PubMed

    Ronk, L L

    1995-06-01

    Although antibiotics can cure most bacterial infections, there is an increasing number of bacteria that are resistant to antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) is becoming increasingly prevalent in US health care facilities. The majority of these infections are found in patients who have extensive burns or surgical wounds. As a result, perioperative nurses must be knowledgeable about MRSA and its implications for the OR. There are many theories on how to control the spread of MRSA but not one definitive set of control measures. Perioperative nurses, in cooperation with infection control practitioners, must develop policies that detail how patients with MRSA will be treated.

  15. Counteracting selection for antibiotic-resistant bacteria

    PubMed Central

    Yosef, Ido; Manor, Miriam; Qimron, Udi

    2016-01-01

    ABSTRACT The occurrence of antibiotic-resistant bacterial pathogens is on the rise because antibiotics exert selection pressure that kills only the antibiotic-sensitive pathogens. Sanitation and cleansing of hospital surfaces and the skin of medical personnel do not counteract this selective pressure, but rather indiscriminately reduce total pathogens on treated surfaces. Here, we discuss two recently introduced genetic strategies, based on temperate bacteriophages as DNA-delivery vehicles, that aim to sensitize bacteria to antibiotics and selectively kill the antibiotic-resistant ones. Outlooks for rendering one such approach more efficient and applicable are proposed. We believe that using an end product designed according to the provided principles on hospital surfaces and in hand-sanitizers will facilitate substitution of antibiotic-resistant pathogens with sensitive ones. PMID:27144084

  16. Counteracting selection for antibiotic-resistant bacteria.

    PubMed

    Yosef, Ido; Manor, Miriam; Qimron, Udi

    2016-01-01

    The occurrence of antibiotic-resistant bacterial pathogens is on the rise because antibiotics exert selection pressure that kills only the antibiotic-sensitive pathogens. Sanitation and cleansing of hospital surfaces and the skin of medical personnel do not counteract this selective pressure, but rather indiscriminately reduce total pathogens on treated surfaces. Here, we discuss two recently introduced genetic strategies, based on temperate bacteriophages as DNA-delivery vehicles, that aim to sensitize bacteria to antibiotics and selectively kill the antibiotic-resistant ones. Outlooks for rendering one such approach more efficient and applicable are proposed. We believe that using an end product designed according to the provided principles on hospital surfaces and in hand-sanitizers will facilitate substitution of antibiotic-resistant pathogens with sensitive ones.

  17. [Travellers and multi-drug resistance bacteria].

    PubMed

    Takeshita, Nozomi

    2012-02-01

    The number of international travellers has increased. There is enormous diversity in medical backgrounds, purposes of travel, and travelling styles among travellers. Travellers are hospitalized abroad because of exotic and common diseases via medical tourism. This is one way of transporting and importing human bacteria between countries, including multi-drug resistant organisms. In developing countries, the antimicrobial resistance in Shigella sp. and Salmonella sp. have been a problem, because of this trend, the first choice of antibiotics has changed in some countries. Community acquired infections as well as hospital acquired infections with MRSA, multi-drug resistance (MDR) Pseudomonas aeruginosa, and ESBL have been a problem. This review will discuss the risk of MDR bacterial infectious diseases for travellers.

  18. Mercury-Resistant Bacteria and Petroleum Degradation

    PubMed Central

    Walker, J. D.; Colwell, R. R.

    1974-01-01

    The concentration of mercury in water and sediment and in the oil extracted from water and sediment was determined for samples collected in Colgate Creek, located in Baltimore Harbor of the Chesapeake Bay. The concentration of mercury in the oil was 4,000 times higher than in sediment and 300,000 times higher than in water samples. The mercury-resistant bacterial populations of the samples studied have been shown to degrade oil, suggesting these bacteria to be a significant factor in the degradation of oil in Colgate Creek. PMID:4809908

  19. [The effect of antibacterial substances on spread resistance of bacteria].

    PubMed

    Chojecka, Agnieszka; Jakimiak, Bozenna; Röhm-Rodowald, Ewa; Podgórska, Marta

    2010-01-01

    The evaluation of influence biocides on phenomenon of spread resistance bacteria is wide discussed particularly in the medical area. Current issue is examinated mechanisms of spread bacterial resistance in the areas using antibiotics and disinfectants and in natural environment. Selection of resistance bacteria is connected with using biocides against the rules in medical care and disinfection. Biocides using in static concentrations do not act as bacteriocidal substances and contribute to survival rate of resistance bacteria. Disinfectants use correctly to the areas and in right using concentrations prevent spread of resistance bacteria.

  20. Antibiotic Resistance of Bacteria in Water Containing Ornamental Fishes

    PubMed Central

    Trust, T. J.; Whitby, J. L.

    1976-01-01

    Water containing ornamental fishes was found to frequently contain countable numbers of bacteria that were resistant to one or more antibiotic or chemotherapeutic agents. The multidrug-resistant strains most commonly isolated were lactose-fermenting Citrobacter freundii. The overall resistance of these aquaria strains was greater than the previously described resistance of clinical isolates of C. freundii. Although the strains examined appeared to lack R-factors, this pool of resistant bacteria may have public health implications. PMID:988781

  1. Prevalence of antibiotic-resistant bacteria in herbal products.

    PubMed

    Brown, Joseph C; Jiang, Xiuping

    2008-07-01

    The objective of this study was to determine the prevalence of antibiotic-resistant bacteria in various herbal products. Twenty-nine herbal supplements (18 traditional and 11 organic products) were purchased from stores and analyzed microbiologically. Total bacterial counts were determined by pour plate and surface spreading on tryptic soy agar (TSA). Antibiotic-resistant bacteria were enumerated on TSA supplemented with ceftriaxone (64 microg/ml) or tetracycline (16 microg/ml). Total bacterial counts ranged from <5 to 2.9 x 10(5) CFU/g. Ceftriaxone- and tetracycline-resistant bacteria were detected in ground garlic samples at 1.1 x 10(2) CFU/g and 3.0 x 102 CFU/g, respectively. Traditional and organic onion powder samples contained tetracycline-resistant bacteria at 17 and 28 CFU/g and ceftriaxone-resistant bacteria at 35 and 2.0 x 10(3) CFU/g, respectively. Other products such as ginger, rosemary, mustard, and goldenseal contained low levels of resistant bacteria. Fifty-two isolates were further evaluated against nine antibiotics, and the prevalence of antibiotic resistance was in the following order: ampicillin, nalidixic acid, trimethoprim, ceftriaxone, and streptomycin. Resistant bacteria were identified as Bacillus spp., Erwinia spp., and Ewingella americana. Staphylococcus spp., Enterobacter cloacae, and Stenotrophomonas maltophilia also were isolated. The presence of antibiotic-resistant bacteria and pathogens in these herbal products suggests that production and use of these products may need further evaluation.

  2. [Diagnosis and management of antibiotic-resistant bacteria].

    PubMed

    Yanagihara, Katsunori; Kamihira, Shimeru

    2012-06-01

    Antibiotic-resistant infections acquired in hospitals are of great concern, and have become a serious public issue. Antibiotic-resistant infections can be associated with a variety of bacteria, such as methicillin resistant Staphylococcus aureus(MRSA) and multidrug-resistant Pseudomonas aeruginosa (MDRP). Since clinical laboratories are responsible for detecting information regarding antibiotic-resistant bacteria, they are required to perform analysis and dissemination of the information. Currently, rapid methods for detecting antibiotic-resistant bacteria using molecular techniques are being developed in response to the problem of the conventional methods for bacteriological testing, which require a few days to obtain results. This article presents the diagnosis and management of antibiotic-resistant bacteria, which comprise a serious health care issue.

  3. Translocatable resistance to mercuric and phenylmercuric ions in soil bacteria

    SciTech Connect

    Radford, A.J.; Oliver, J.; Kelly, W.J.; Reaney, D.C.

    1981-08-01

    Of a sample of 42 grams-negative Hg-resistant bacteria, three (a Pseudomonas fluorescens, a Klebsiella sp. and a Citrobacter sp.) contained translocatable elements conferring resistance to Hgbj (all three) and to Hgbj and phenylmercuric acetate (P. fluorescens). The discovery of transposable phenylmercuric acetate resistance extends the range of known resistance ''transposons'' from heavy metals and antibiotics to organometallic compounds.

  4. Multiple antibiotic resistance among gram negative bacteria isolated from poultry.

    PubMed

    Ansari, F A; Khatoon, H

    1994-03-01

    Gram negative bacteria, including species of Salmonella, Escherichia, Pseudomonas and Klebsiella, isolated from poultry, were screened for their resistance to the commonly used antibiotics: ampicillin, chloramphenicol, gentamycin, kanamycin, neomycin, polymyxin B, streptomycin and tetracycline. Of the 500 bacteria screened, 351 were found to be resistant to one or more antibiotics at the level of 50 micrograms/ml. Various patterns of antibiotic resistance observed during these studies have been reported.

  5. [Multi-drug resistant bacteria, a complex mechanism].

    PubMed

    Hilaire, Jean-Christophe

    2013-01-01

    Bacteria are said to be multidrug resistant when they are only sensitive to a small number of antibiotics used as treatments. This problem of resistance appeared in hospitals soon after antibiotics were first used. In the 1960s, strains of staphylococcus became resistant to penicillin.

  6. Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria.

    PubMed

    Nawrocki, Kathryn L; Crispell, Emily K; McBride, Shonna M

    2014-10-13

    Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis.

  7. Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria

    PubMed Central

    Nawrocki, Kathryn L.; Crispell, Emily K.; McBride, Shonna M.

    2014-01-01

    Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis. PMID:25419466

  8. Rapid electrochemical phenotypic profiling of antibiotic-resistant bacteria.

    PubMed

    Besant, Justin D; Sargent, Edward H; Kelley, Shana O

    2015-07-07

    Rapid phenotyping of bacteria to identify drug-resistant strains is an important capability for the treatment and management of infectious disease. At present, the rapid determination of antibiotic susceptibility is hindered by the requirement that, in existing devices, bacteria must be pre-cultured for 2-3 days to reach detectable levels. Here we report a novel electrochemical approach that achieves rapid readout of the antibiotic susceptibility profile of a bacterial infection within one hour. The electrochemical reduction of a redox-active molecule is monitored that reports on levels of metabolically-active bacteria. Bacteria are captured in miniaturized wells, incubated with antimicrobials and monitored for resistance. This electrochemical phenotyping approach is effective with clinically-relevant levels of bacteria, and provides results comparable to culture-based analysis. Results, however, are delivered on a much faster timescale, with resistance profiles available after a one hour incubation period.

  9. [Role of lactic acid bacteria in the spread of antibiotic resistant bacteria among healthy persons].

    PubMed

    Zigangirova, N A; Tokarskaia, E A; Narodnitskiĭ, B S; Gintsburg, A L; Tugel'ian, V A

    2006-01-01

    The wide use of antibiotics in livestock raising has contributed to the selection and accumulation of representatives of commensal microflora, as well as pathogenic bacteria, colonizing livestock and poultry. For this reason the problem of the possible transfer of antibiotic-resistance genes along the chain from bacteria, autochthonous for agricultural animals, to bacteria used for the production of foodstuffs, which are incorporated into normal microflora and may thus participate in the exchange of these genes with bacteria, enteropathogenic for humans, is a highly important task of medical microbiology. The article deals with the review of experimental data, indicative the possibility of the appearance of antibiotic-resistant pathogenic bacteria due to the transfer of antibiotic-resistance genes via alimentary chains.

  10. Probing minority population of antibiotic-resistant bacteria.

    PubMed

    Huang, Tianxun; Zheng, Yan; Yan, Ya; Yang, Lingling; Yao, Yihui; Zheng, Jiaxin; Wu, Lina; Wang, Xu; Chen, Yuqing; Xing, Jinchun; Yan, Xiaomei

    2016-06-15

    The evolution and spread of antibiotic-resistant pathogens has become a major threat to public health. Advanced tools are urgently needed to quickly diagnose antibiotic-resistant infections to initiate appropriate treatment. Here we report the development of a highly sensitive flow cytometric method to probe minority population of antibiotic-resistant bacteria via single cell detection. Monoclonal antibody against TEM-1 β-lactamase and Alexa Fluor 488-conjugated secondary antibody were used to selectively label resistant bacteria green, and nucleic acid dye SYTO 62 was used to stain all the bacteria red. A laboratory-built high sensitivity flow cytometer (HSFCM) was applied to simultaneously detect the side scatter and dual-color fluorescence signals of single bacteria. By using E. coli JM109/pUC19 and E. coli JM109 as the model systems for antibiotic-resistant and antibiotic-susceptible bacteria, respectively, as low as 0.1% of antibiotic-resistant bacteria were accurately quantified. By monitoring the dynamic population change of a bacterial culture with the administration of antibiotics, we confirmed that under the antimicrobial pressure, the original low population of antibiotic-resistant bacteria outcompeted susceptible strains and became the dominant population after 5hours of growth. Detection of antibiotic-resistant infection in clinical urine samples was achieved without cultivation, and the bacterial load of susceptible and resistant strains can be faithfully quantified. Overall, the HSFCM-based quantitative method provides a powerful tool for the fundamental studies of antibiotic resistance and holds the potential to provide rapid and precise guidance in clinical therapies. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Environmental Macrolide–Lincosamide–Streptogramin and Tetracycline Resistant Bacteria

    PubMed Central

    Roberts, Marilyn C.

    2010-01-01

    Bacteria can become resistant to antibiotics by mutation, transformation, and/or acquisition of new genes which are normally associated with mobile elements (plasmids, transposons, and integrons). Mobile elements are the main driving force in horizontal gene transfer between strains, species, and genera and are responsible for the rapid spread of particular elements throughout a bacterial community and between ecosystems. Today, antibiotic resistant bacteria are widely distributed throughout the world and have even been isolated from environments that are relatively untouched by human civilization. In this review macrolides, lincosamides, streptogramins, and tetracycline resistance genes and bacteria will be discussed with an emphasis on the resistance genes which are unique to environmental bacteria which are defined for this review as species and genera that are primarily found outside of humans and animals. PMID:21833302

  12. Stalking Antibiotic-Resistant Bacteria in Common Vegetables

    ERIC Educational Resources Information Center

    Brock, David; Boeke, Caroline; Josowitz, Rebecca; Loya, Katherine

    2004-01-01

    The study developed a simple experimental protocol for studying antibiotic resistant bacteria that will allow students to determine the proportion of such bacteria found on common fruit and vegetable crops. This protocol can open up the world of environmental science and show how human behavior can dramatically alter ecosystems.

  13. Stalking Antibiotic-Resistant Bacteria in Common Vegetables

    ERIC Educational Resources Information Center

    Brock, David; Boeke, Caroline; Josowitz, Rebecca; Loya, Katherine

    2004-01-01

    The study developed a simple experimental protocol for studying antibiotic resistant bacteria that will allow students to determine the proportion of such bacteria found on common fruit and vegetable crops. This protocol can open up the world of environmental science and show how human behavior can dramatically alter ecosystems.

  14. General principles of antibiotic resistance in bacteria.

    PubMed

    Martinez, Jose L

    2014-03-01

    Given the impact of antibiotic resistance on human health, its study is of great interest from a clinical view- point. In addition, antibiotic resistance is one of the few examples of evolution that can be studied in real time. Knowing the general principles involved in the acquisition of antibiotic resistance is therefore of interest to clinicians, evolutionary biologists and ecologists. The origin of antibiotic resistance genes now possessed by human pathogens can be traced back to environmental microorganisms. Consequently, a full understanding of the evolution of antibiotic resistance requires the study of natural environments as well as clinical ecosystems. Updated information on the evolutionary mechanisms behind resistance, indicates that ecological connectivity, founder effect and fitness costs are important bottle- necks that modulate the transfer of resistance from environmental microorganisms to pathogens.

  15. Insect Antimicrobial Peptide Complexes Prevent Resistance Development in Bacteria

    PubMed Central

    Chernysh, Sergey; Gordya, Natalia; Suborova, Tatyana

    2015-01-01

    In recent decades much attention has been paid to antimicrobial peptides (AMPs) as natural antibiotics, which are presumably protected from resistance development in bacteria. However, experimental evolution studies have revealed prompt resistance increase in bacteria to any individual AMP tested. Here we demonstrate that naturally occurring compounds containing insect AMP complexes have clear advantage over individual peptide and small molecule antibiotics in respect of drug resistance development. As a model we have used the compounds isolated from bacteria challenged maggots of Calliphoridae flies. The compound isolated from blow fly Calliphora vicina was found to contain three distinct families of cell membrane disrupting/permeabilizing peptides (defensins, cecropins and diptericins), one family of proline rich peptides and several unknown antimicrobial substances. Resistance changes under long term selective pressure of the compound and reference antibiotics cefotaxime, meropenem and polymyxin B were tested using Escherichia coli, Klebsiella pneumonia and Acinetobacter baumannii clinical strains. All the strains readily developed resistance to the reference antibiotics, while no signs of resistance growth to the compound were registered. Similar results were obtained with the compounds isolated from 3 other fly species. The experiments revealed that natural compounds containing insect AMP complexes, in contrast to individual AMP and small molecule antibiotics, are well protected from resistance development in bacteria. Further progress in the research of natural AMP complexes may provide novel solutions to the drug resistance problem. PMID:26177023

  16. Antibiotic-Resistant Bacteria: There is Hope.

    ERIC Educational Resources Information Center

    Offner, Susan

    1998-01-01

    Argues that reduction in the use of antibiotics would enable antibiotic-sensitive bacteria to flourish. Presents an activity designed to show students how a small, seemingly unimportant difference in doubling time can, over a period of time, make an enormous difference in population size. (DDR)

  17. Antibiotic-Resistant Bacteria: There is Hope.

    ERIC Educational Resources Information Center

    Offner, Susan

    1998-01-01

    Argues that reduction in the use of antibiotics would enable antibiotic-sensitive bacteria to flourish. Presents an activity designed to show students how a small, seemingly unimportant difference in doubling time can, over a period of time, make an enormous difference in population size. (DDR)

  18. Marine bacteria: potential sources for compounds to overcome antibiotic resistance.

    PubMed

    Eom, Sung-Hwan; Kim, Young-Mog; Kim, Se-Kwon

    2013-06-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is the most problematic Gram-positive bacterium in the context of public health due to its resistance against almost all available antibiotics except vancomycin and teicoplanin. Moreover, glycopeptide-resistant S. aureus have been emerging with the increasing use of glycopeptides. Recently, resistant strains against linezolid and daptomycin, which are alternative drugs to treat MRSA infection, have also been reported. Thus, the development of new drugs or alternative therapies is clearly a matter of urgency. In response to the antibiotic resistance, many researchers have studied for alternative antibiotics and therapies. In this review, anti-MRSA substances isolated from marine bacteria, with their potential antibacterial effect against MRSA as potential anti-MRSA agents, are discussed and several strategies for overcoming the antibiotic resistance are also introduced. Our objective was to highlight marine bacteria that have potential to lead in developing novel antibiotics or clinically useful alternative therapeutic treatments.

  19. [The rise of resistant gram-negative bacteria].

    PubMed

    Kuijper, Ed J; van Dissel, Jaap T

    2010-01-01

    During the past few years there has been a global spread of resistant gram-negative bacteria that are insensitive to cephalosporins and carbapenems. Extended spectrum beta-lactamase (ESBL)-producing bacteria are capable of inactivating the newest generation of cephalosporins. It is notable that ESBL-producing bacteria are found predominantly outside the hospital situation in the environment, in food and in meat products, which leads to the presumption that the food chain is contributing to the rapid spread of these bacteria. Several types of carbapenemase-producing bacteria have been distinguished, of which the 'New Delhi metallo beta-lactamase 1 (NDM-1)' type seems to be prevalent in Asia outside the hospital situation in the community, and is now being transmitted to other continents as a result of migration and tourism. With the rise of ESBL- and carbapenemase-producing gram-negative bacteria (which are also often resistant to most other antibiotics) comes the very real concern that treatment of infections such as urinary tract infections that are currently simple to treat with common oral antibiotics will be problematic in the future. The widespread use of antibiotics in animal husbandry is an important factor in the problem of antibiotic resistance. Since economic motives are of importance, a coordinated approach from many parties concerned will be necessary, not just from the medical sector but also from the veterinary and agricultural world, and from food producers and pharmaceutical companies to combat the spread of multiresistant gram-negative bacteria effectively.

  20. Ethanologenic bacteria with increased resistance to furfural

    DOEpatents

    Miller, Elliot Norman; Jarboe, Laura R.; Yomano, Lorraine P.; York, Sean W.; Shanmugam, Keelnatham; Ingram, Lonnie O'Neal

    2015-10-06

    The invention relates to bacterium that have increased resistance to furfural and methods of preparation. The invention also relates to methods of producing ethanol using the bacterium and corresponding kits.

  1. Macrolides resistance of common bacteria isolated from Taiwan.

    PubMed

    Chang, S C; Chen, Y C; Luh, K T; Hsieh, W C

    1995-12-01

    To determine the susceptibility to macrolides of common pathogenic bacteria isolated from Taiwan, the in vitro activities of erythromycin, roxithromycin, azithromycin, clarithromycin, and dirithromycin were tested against 492 clinical isolates of eight different bacteria, collected from the National Taiwan University Hospital. The results showed high minimum inhibitory concentrations (MICs) against most of the tested bacteria. The MIC90s for Staphylococcus aureus (both methicillin-resistant and -sensitive strains), coagulase-negative staphylococci (both methicillin-resistant and -sensitive strains), Streptococcus pyogenes, Streptococcus pneumoniae, enterococci, peptostreptococci, and Bacteroides fragilis were all > or = 256 micrograms/ml. The MIC50s for methicillin-resistant strains of S. aureus and coagulase-negative staphylococci, and enterococci were > or = 256 micrograms/ml. For S. pneumoniae, peptostreptococci, and B. fragilis, the MIC50s were > 8 micrograms/ml. The resistance rates to macrolides were 80% or more in methicillin-resistant staphylococci and about 30% in methicillin-sensitive staphylococci. Around 55% of S. pneumoniae strains and 37 approximately 42% of S. pyogenes strains were resistant to macrolides. Cross-resistance to different macrolides was clearly demonstrated in most of the resistant strains.

  2. Presence of Multidrug Resistant Enteric Bacteria in Dairy Farm Topsoil

    PubMed Central

    Burgos, J. M.; Ellington, B. A.; Varela, M. F.

    2008-01-01

    In addition to human and veterinary medicine, antibiotics are extensively used in agricultural settings, such as for treatment of infections, growth enhancement and prophylaxis in food animals, leading to selection of drug and multidrug resistant bacteria. In order to help circumvent the problem of bacterial antibiotic resistance, it is first necessary to understand the scope of the problem. However, is it not fully understood how widespread antibiotic resistant bacteria are in agricultural settings. The lack of such surveillance data is especially evident in dairy farm environments, such as soil. It is also unknown to what extent various physiological modulators, such as salycilate, a component of aspirin and known model modulator of multiple antibiotic resistance (mar) genes, influence bacterial multidrug resistance. We isolated and identified enteric soil bacteria from local dairy farms within Roosevelt County, NM, determined the resistance profiles to antibiotics associated with mar, such as chloramphenicol, nalidixic acid, penicillin G and tetracycline. We then purified and characterized plasmid DNA and detected mar phenotypic activity. The minimal inhibitory concentrations (MICs) of antibiotics for the isolates ranged between 6 - >50 μg/mL for chloramphenicol, 2–8 μg/mL for nalidixic acid, 25- >300 μg/mL for penicillin G and 1- > 80 μg/mL for tetracycline. On the other hand, the many of the isolates had significantly enhanced MICs for the same antibiotics in the presence of 5 mM salycilate. Plasmid DNA extracted from 12 randomly chosen isolates ranged in size between 6 and 12.5kb and in several cases conferred resistances to chloramphenicol and penicillin G. It is concluded that enteric bacteria from dairy farm topsoil are multi-drug resistant and harbor antibiotic resistance plasmids. A role for dairy topsoil in zoonosis is suggested, thus implicating this environment as a reservoir for bacterial resistance development against clinically relevant

  3. [Update on antibiotic resistance in Gram-positive bacteria].

    PubMed

    Lozano, Carmen; Torres, Carmen

    2017-01-01

    Antimicrobial resistance among Gram-positive bacteria, especially in Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, and Streptococcus pneumoniae, is a serious threat to public health. These microorganisms have multiple resistance mechanisms to agents currently used in clinical practice. Many of these resistance mechanisms are common to all 4 of these bacterial species, but other mechanisms seem to be more specific. The prevalence and dissemination of these mechanisms varies considerably, depending on the microorganism. This review discusses the resistance mechanisms to the most clinically relevant antibiotics, with particular emphasis on the new mechanisms described for widely used antibiotics and for newer agents such as lipopeptides, lipoglycopeptides, glycylcyclines and oxazolidinones.

  4. Current and novel antibiotics against resistant Gram-positive bacteria

    PubMed Central

    Perez, Federico; Salata, Robert A; Bonomo, Robert A

    2008-01-01

    The challenge posed by resistance among Gram-positive bacteria, epitomized by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and vancomycin-intermediate and -resistant S. aureus (VISA and VRSA) is being met by a new generation of antimicrobials. This review focuses on the new β-lactams with activity against MRSA (ceftobiprole and ceftaroline) and on the new glycopeptides (oritavancin, dalbavancin, and telavancin). It will also consider the role of vancomycin in an era of existing alternatives such as linezolid, daptomycin and tigecycline. Finally, compounds in early development are described, such as iclaprim, friulimicin, and retapamulin, among others. PMID:21694878

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

    PubMed Central

    Band, Victor I.; Weiss, David S.

    2014-01-01

    Cationic antimicrobial peptides (CAMPs) are important innate immune defenses that inhibit colonization by pathogens and contribute to clearance of infections. Gram-negative bacterial pathogens are a major target, yet many of them have evolved mechanisms to resist these antimicrobials. These resistance mechanisms can be critical contributors to bacterial virulence and are often crucial for survival within the host. Here, we summarize methods used by Gram-negative bacteria to resist CAMPs. Understanding these mechanisms may lead to new therapeutic strategies against pathogens with extensive CAMP resistance. PMID:25927010

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

    PubMed

    Band, Victor I; Weiss, David S

    2015-03-01

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

  7. Plasmid mediated antibiotic resistance in isolated bacteria from burned patients.

    PubMed

    Beige, Fahimeh; Baseri Salehi, Majid; Bahador, Nima; Mobasherzadeh, Sina

    2015-01-01

    Nowadays, the treatment of burned patients is difficult because of the high frequency of infection with antibiotic resistance bacteria. This study was conducted to evaluate the level of antibiotic resistance in Gram-negative bacteria and its relation with the existence of plasmid. The samples were collected from two hundred twenty hospitalized burned patients in Isfahan burn hospital during a three-month period (March 2012 to June 2012). The samples were isolated and the Gram-negative bacteria were identified using phenotypic method and API 20E System. Antibiotic susceptibility and plasmid profile were determined by standard Agar disc diffusion and plasmid spin column extraction methods. Totally 117 Gram-negative bacteria were isolated, the most common were Pseudomonas aerugionsa (37.6%), P. fluorescens (25.6%), Acinetobacter baumanii (20/5%) and Klebsiella pneumoniae (7.6%), respectively. The isolates showed high frequency of antibiotic resistance against ceftazidime and co-amoxiclave (100%) and low frequency of antibiotic resistance against amikacin with (70%).The results indicated that 60% of the isolates harboured plasmid. On the other hand, the patients infected with A. baumanii and P. aeruginosa were cured (with 60% frequency) whereas, those infected with P. fluorescens were not cured. Hence, probably antibiotic resistance markers of A. baumanii and P. aeruginosa are plasmid mediated; however, P. fluorescens is chromosomally mediated. Based on our findings, P. aerugionsa is a major causative agent of wound infections and amikacin could be considered as a more effective antibiotic for treatment of the burned patients.

  8. Quinolone resistance in bacteria: emphasis on plasmid-mediated mechanisms.

    PubMed

    Li, Xian-Zhi

    2005-06-01

    Bacterial resistance to quinolones/fluoroquinolones has emerged rapidly and such resistance has traditionally been attributed to the chromosomally mediated mechanisms that alter the quinolone targets (i.e. DNA gyrase and topoisomerase IV) and/or overproduce multidrug resistance efflux pumps. However, the discovery of the plasmid-borne quinolone resistance determinant, named qnr, has substantially broadened our horizon on the molecular mechanisms of quinolone resistance. Several recent reports of Qnr or its homologues encoded by transferable plasmids in Gram-negative bacteria isolated worldwide highlight the significance of the emerging plasmid-mediated mechanism(s). This also alerts us to the potential rapid dissemination of quinolone resistance determinants. Qnr belongs to the pentapeptide repeat family and protects DNA gyrase from the action of quinolone agents including the newer fluoroquinolones. This protection interplays with chromosomal mechanisms to raise significantly the resistance levels. The qnr-bearing strains generate quinolone-resistant mutants at a much higher frequency than those qnr-free strains. Furthermore, the qnr-plasmids are integron-associated and carry multiple resistance determinants providing resistance to several classes of antimicrobials including beta-lactams and aminoglycosides. The high quinolone resistance rates in Escherichia coli are used to address issues of quinolone resistance, and possible strategies for minimising quinolone resistance are discussed.

  9. The Goldilocks Principle and Antibiotic Resistance in Bacteria

    PubMed Central

    Zhang, Qiucen; Robin, Kristelle; Liao, David; Lambert, Guillaume; Austin, Robert H.

    2011-01-01

    We have designed and fabricated a micro-ecology to mimic the naturally occurring bacterial culture, which includes stress gradient, metapopulation and cellular motility. In this micro-ecology, we show it is possible to fix resistance to the mutagenic antibiotic ciprofloxacin in wild-type E. coli within 10 hours. We found the evolution of resistance is further accelerated in micro-ecology if bacteria have already acquired the phenotype of growth advantage at stationary phase (GASP). PMID:22085251

  10. Spore-Forming Bacteria that Resist Sterilization

    NASA Technical Reports Server (NTRS)

    LaDuc, Myron; Venkateswaran, Kasthuri

    2003-01-01

    A report presents a phenotypic and genotypic characterization of a bacterial species that has been found to be of the genus Bacillus and has been tentatively named B. odysseensis because it was isolated from surfaces of the Mars Odyssey spacecraft as part of continuing research on techniques for sterilizing spacecraft to prevent contamination of remote planets by terrestrial species. B. odysseensis is a Gram-positive, facultatively anaerobic, rod-shaped bacterium that forms round spores. The exosporium has been conjectured to play a role in the elevated resistance to sterilization. Research on the exosporium is proposed as a path toward improved means of sterilization, medical treatment, and prevention of biofouling.

  11. Tackling Threats and Future Problems of Multidrug-Resistant Bacteria.

    PubMed

    Medina, Eva; Pieper, Dietmar Helmut

    2016-01-01

    With the advent of the antibiotic era, the overuse and inappropriate consumption and application of antibiotics have driven the rapid emergence of multidrug-resistant pathogens. Antimicrobial resistance increases the morbidity, mortality, length of hospitalization and healthcare costs. Among Gram-positive bacteria, Staphylococcus aureus (MRSA) and multidrug-resistant (MDR) Mycobacterium tuberculosis, and among the Gram-negative bacteria, extended-spectrum beta-lactamase (ESBLs)-producing bacteria have become a major global healthcare problem in the 21st century. The pressure to use antibiotics guarantees that the spread and prevalence of these as well as of future emerging multidrug-resistant pathogens will be a persistent phenomenon. The unfeasibility of reversing antimicrobial resistance back towards susceptibility and the critical need to treat bacterial infection in modern medicine have burdened researchers and pharmaceutical companies to develop new antimicrobials effective against these difficult-to-treat multidrug-resistant pathogens. However, it can be anticipated that antibiotic resistance will continue to develop more rapidly than new agents to treat these infections become available and a better understanding of the molecular, evolutionary and ecological mechanisms governing the spread of antibiotic resistance is needed. The only way to curb the current crisis of antimicrobial resistance will be to develop entirely novel strategies to fight these pathogens such as combining antimicrobial drugs with other agents that counteract and obstruct the antibiotic resistant mechanisms expressed by the pathogen. Furthermore, as many antibiotics are often inappropriately prescribed, a more personalized approach based on precise diagnosis tools will ensure that proper treatments can be promptly applied leading to more targeted and effective therapies. However, in more general terms, also the overall use and release of antibiotics in the environment needs to be

  12. Antimicrobial-Resistant Enteric Bacteria from Dairy Cattle▿

    PubMed Central

    Sawant, Ashish A.; Hegde, Narasimha V.; Straley, Beth A.; Donaldson, Sarah C.; Love, Brenda C.; Knabel, Stephen J.; Jayarao, Bhushan M.

    2007-01-01

    A study was conducted to understand the descriptive and molecular epidemiology of antimicrobial-resistant gram-negative enteric bacteria in the feces of healthy lactating dairy cattle. Gram-negative enteric bacteria resistant to ampicillin, florfenicol, spectinomycin, and tetracycline were isolated from the feces of 35, 8, 5, and 42% of 213 lactating cattle on 74, 39, 9, 26, and 82% of 23 farms surveyed, respectively. Antimicrobial-resistant gram-negative bacteria accounted for 5 (florfenicol) to 14% (tetracycline) of total gram-negative enteric microflora. Nine bacterial species were isolated, of which Escherichia coli (87%) was the most predominant species. MICs showing reduced susceptibility to ampicillin, ceftiofur, chloramphenicol, florfenicol, spectinomycin, streptomycin, and tetracycline were observed in E. coli isolates. Isolates exhibited resistance to ampicillin (48%), ceftiofur (11%), chloramphenicol (20%), florfenicol (78%), spectinomycin (18%), and tetracycline (93%). Multidrug resistance (≥3 to 6 antimicrobials) was seen in 40% of E. coli isolates from healthy lactating cattle. Of 113 tetracycline-resistant E. coli isolates, tet(B) was the predominant resistance determinant and was detected in 93% of isolates, while the remaining 7% isolates carried the tet(A) determinant. DNA-DNA hybridization assays revealed that tet determinants were located on the chromosome. Pulsed-field gel electrophoresis revealed that tetracycline-resistant E. coli isolates (n = 99 isolates) belonged to 60 subtypes, which is suggestive of a highly diverse population of tetracycline-resistant organisms. On most occasions, E. coli subtypes, although shared between cows within the herd, were confined mostly to a dairy herd. The findings of this study suggest that commensal enteric E. coli from healthy lactating cattle can be an important reservoir for tetracycline and perhaps other antimicrobial resistance determinants. PMID:17098918

  13. Drug resistant bacteria in non carbonated mineral waters.

    PubMed

    Massa, S; Petruccioli, M; Fanelli, M; Gori, L

    1995-11-01

    The presence of antibiotic resistant bacteria was revealed among bacteria isolated from non carbonated mineral waters bottled in plastic (PVC) and in glass containers. Heterotrophic plate count values ranged between < 10 and 4.3 x 10(3) and between < 10 and 1.2 x 10(4) colony forming units/ml for the waters bottled in PVC and glass, respectively. The greatest resistance to a single antibiotic, 39.1% of 320 isolates from mineral waters, was found for nalidixic acid. Resistance to the other antibiotics was as follows: ampicillin (26.2%), bacitracin (19.7%), cotrimoxazole (18.7%), streptomycin (15.0%), tetracycline (14.4%), gentamycin (11.6%), chloramphenicol and rifampin (9.7%). The strains resistant to two or more antibiotics (multiple antibiotic resistant, MAR) provided 51% of the total isolates. Identification of 127 MAR strains showed that in the mineral waters gram-positive cocci dominated. The second, third and fourth group of identified MAR phenotypes were, in order to importance, gram-negative non-fermentative rods, gram-positive rods and gram-negative fermentative rods. The importance of the antibiotic resistant bacteria in mineral water is discussed.

  14. Bacteria from Animals as a Pool of Antimicrobial Resistance Genes

    PubMed Central

    Argudín, Maria Angeles; Deplano, Ariane; Meghraoui, Alaeddine; Dodémont, Magali; Heinrichs, Amelie; Denis, Olivier; Nonhoff, Claire; Roisin, Sandrine

    2017-01-01

    Antimicrobial agents are used in both veterinary and human medicine. The intensive use of antimicrobials in animals may promote the fixation of antimicrobial resistance genes in bacteria, which may be zoonotic or capable to transfer these genes to human-adapted pathogens or to human gut microbiota via direct contact, food or the environment. This review summarizes the current knowledge of the use of antimicrobial agents in animal health and explores the role of bacteria from animals as a pool of antimicrobial resistance genes for human bacteria. This review focused in relevant examples within the ESC(K)APE (Enterococcus faecium, Staphylococcus aureus, Clostridium difficile (Klebsiella pneumoniae), Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae) group of bacterial pathogens that are the leading cause of nosocomial infections throughout the world. PMID:28587316

  15. Antimicrobial-resistant bacteria in wild game in Slovenia

    NASA Astrophysics Data System (ADS)

    Križman, M.; Kirbiš, A.; Jamnikar-Ciglenečki, U.

    2017-09-01

    Wildlife is usually not exposed to clinically-used antimicrobial agents but can acquire antimicrobial resistance throughout contact with humans, domesticated animals and environments. Samples of faeces from intestines (80 in total) were collected from roe deer (52), wild boars (11), chamois (10) red deer (6) and moufflon (1). After culture on ChromID extended spectrum β-lactamase (ESBL) plates to select for growth of ESBL-producing bacteria, 25 samples produced bacterial colonies for further study. Six species of bacteria were identified from the 25 samples: Stenotrophomonas maltophilia, Serratia fonticola, Stenotrophomonas nitritireducens, Enterococcus faecium, Enterococcus faecalis and Escherichia coli. Two ESBL enzymes were amplified from group TEM and three from group CTX-M-1. Undercooked game meat and salami can be a source of resistant bacteria when animals are not eviscerated properly.

  16. Triclosan- resistant bacteria isolated from feedlot and residential soils

    PubMed Central

    WELSCH, TANNER T.; GILLOCK, ERIC T.

    2014-01-01

    Triclosan is an antimicrobial agent that is currently incorporated into hundreds of consumer and medical products. It can be either a bacteriostatic or bactericidal agent, depending on its formulation. It has activity against Gram-positive and Gram-negative bacteria, as well as some viruses and protists. The purpose of this study was to determine whether triclosan-resistant bacteria could be isolated from the soil. Soils from cattle feedlots and residential lawns were collected and assayed for the presence of these organisms by plating samples on growth media containing triclosan. Organisms were subsequently identified by partial 16S rRNA sequencing analysis. All the organisms isolated in this study were Gram-negative rods, with members of genus Pseudomonas being particularly well represented. This result may not be surprising because Gram-negative organisms are generally more resistant to triclosan, and since Pseudomonas bacteria are known to have numerous efflux mechanisms for dealing with harmful substances. PMID:21391038

  17. Triclosan-resistant bacteria isolated from feedlot and residential soils.

    PubMed

    Welsch, Tanner T; Gillock, Eric T

    2011-01-01

    Triclosan is an antimicrobial agent that is currently incorporated into hundreds of consumer and medical products. It can be either a bacteriostatic or bactericidal agent, depending on its formulation. It has activity against Gram-positive and Gram-negative bacteria, as well as some viruses and protists. The purpose of this study was to determine whether triclosan-resistant bacteria could be isolated from the soil. Soils from cattle feedlots and residential lawns were collected and assayed for the presence of these organisms by plating samples on growth media containing triclosan. Organisms were subsequently identified by partial 16S rRNA sequencing analysis. All the organisms isolated in this study were Gram-negative rods, with members of genus Pseudomonas being particularly well represented. This result may not be surprising because Gram-negative organisms are generally more resistant to triclosan, and since Pseudomonas bacteria are known to have numerous efflux mechanisms for dealing with harmful substances.

  18. Efflux-Mediated Drug Resistance in Bacteria: an Update

    PubMed Central

    Li, Xian-Zhi; Nikaido, Hiroshi

    2010-01-01

    Drug efflux pumps play a key role in drug resistance and also serve other functions in bacteria. There has been a growing list of multidrug and drug-specific efflux pumps characterized from bacteria of human, animal, plant and environmental origins. These pumps are mostly encoded on the chromosome although they can also be plasmid-encoded. A previous article (Li X-Z and Nikaido H, Drugs, 2004; 64[2]: 159–204) had provided a comprehensive review regarding efflux-mediated drug resistance in bacteria. In the past five years, significant progress has been achieved in further understanding of drug resistance-related efflux transporters and this review focuses on the latest studies in this field since 2003. This has been demonstrated in multiple aspects that include but are not limited to: further molecular and biochemical characterization of the known drug efflux pumps and identification of novel drug efflux pumps; structural elucidation of the transport mechanisms of drug transporters; regulatory mechanisms of drug efflux pumps; determining the role of the drug efflux pumps in other functions such as stress responses, virulence and cell communication; and development of efflux pump inhibitors. Overall, the multifaceted implications of drug efflux transporters warrant novel strategies to combat multidrug resistance in bacteria. PMID:19678712

  19. Elevated Rate of Genome Rearrangements in Radiation-Resistant Bacteria

    PubMed Central

    Repar, Jelena; Supek, Fran; Klanjscek, Tin; Warnecke, Tobias; Zahradka, Ksenija; Zahradka, Davor

    2017-01-01

    A number of bacterial, archaeal, and eukaryotic species are known for their resistance to ionizing radiation. One of the challenges these species face is a potent environmental source of DNA double-strand breaks, potential drivers of genome structure evolution. Efficient and accurate DNA double-strand break repair systems have been demonstrated in several unrelated radiation-resistant species and are putative adaptations to the DNA damaging environment. Such adaptations are expected to compensate for the genome-destabilizing effect of environmental DNA damage and may be expected to result in a more conserved gene order in radiation-resistant species. However, here we show that rates of genome rearrangements, measured as loss of gene order conservation with time, are higher in radiation-resistant species in multiple, phylogenetically independent groups of bacteria. Comparison of indicators of selection for genome organization between radiation-resistant and phylogenetically matched, nonresistant species argues against tolerance to disruption of genome structure as a strategy for radiation resistance. Interestingly, an important mechanism affecting genome rearrangements in prokaryotes, the symmetrical inversions around the origin of DNA replication, shapes genome structure of both radiation-resistant and nonresistant species. In conclusion, the opposing effects of environmental DNA damage and DNA repair result in elevated rates of genome rearrangements in radiation-resistant bacteria. PMID:28188144

  20. Bacteria-Mineral Interactions on the Surfaces of Metal-Resistant Bacteria

    SciTech Connect

    Malkin, A J

    2010-03-24

    The extraordinary ability of indigenous microorganisms, like metal-resistant bacteria, for biotransformation of toxic compounds is of considerable interest for the emerging area of environmental bioremediation. However, the underlying mechanisms by which metal-resistant bacteria transform toxic compounds are currently unknown and await elucidation. The project's objective was to study stress-induced responses of metal-resistant bacteria to environmental changes and chemical stimulants. This project involved a multi-institutional collaboration of our LLNL group with the group of Dr. H.-Y. Holman (Lawrence Berkeley National Laboratory). In this project, we have utilized metal-resistant bacteria Arthrobacter oxydans as a model bacterial system. We have utilized atomic force microscopy (AFM) to visualize for the first time at the nanometer scale formation of stress-induced structures on bacterial surfaces in response to Cr (VI) exposure. We have demonstrated that structure, assembly, and composition of these stress-induced structures are dependent on Cr (VI) concentrations. Our AFM observations of the appearance and development of stress-induced layers on the surfaces of Arthrobacter oxydans bacteria exposed to Cr (VI) were confirmed by Dr. Holman's biochemical, electron microscopy, and synchrotron infrared spectromicroscopy studies. In general, in vitro imaging of live microbial and cellular systems represents one of the most challenging issues in application of AFM. Various approaches for immobilization of bacteria on the substrate for in vitro imaging were tested in this project. Imaging of live bacteria was achieved, however further optimization of experimental methods are needed for high-resolution visualization of the cellular environmental structural dynamics by AFM. This project enhanced the current insight into molecular architecture, structural and environmental variability of bacterial systems. The project partially funded research for two book chapters (1

  1. Resistance to quaternary ammonium compounds in food-related bacteria.

    PubMed

    Sidhu, Maan Singh; Sørum, Henning; Holck, Askild

    2002-01-01

    Microbial resistance to antimicrobial agents continues to be a major problem. The frequent use and misuse of disinfectants based on quaternary ammonium compounds (QACs) in food-processing industries have imposed a selective pressure and may contribute to the emergence of disinfectant-resistant microorganisms. A total number of 1,325 Gram-negative isolates (Escherichia coli, other coliforms Vibrio spp., and Aeromonas spp.) and 500 Enterococcus spp. from food and food-processing industries and fish farming were screened for natural resistance to the QAC-based disinfectant benzalkonium chloride (BC). Of the 1,825 isolates, 16 strains, mainly from meat retail shops, showed low-level resistance to BC. None of the Enterococcus spp. from broiler, cattle, and pigs, the antibiotic-resistant E. coli from pig intestine and fish pathogens Vibrio spp. and Aeromonas spp. from the Norwegian fish farming industry were resistant to BC. The BC-resistant strains were examined for susceptibility to 15 different antibiotics, disinfectants, and dyes. No systematic cross-resistance between BC and any of the other antimicrobial agents tested was detected. Stable enhanced resistance in Enterobacter cloacae isolates was demonstrated by step-wise adaptation in increasing concentrations of BC. In conclusion, BC resistance among food-associated Gram-negative bacteria and Enterococcus spp. is not frequent, but resistance may develop to user concentrations after exposure to sublethal concentrations of BC.

  2. Antibiotic Resistance of Diverse Bacteria from Aquaculture in Borneo

    PubMed Central

    Kathleen, M. M.; Felecia, C.; Reagan, E. L.; Kasing, A.; Lesley, M.; Toh, S. C.

    2016-01-01

    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. PMID:27746817

  3. Ultraviolet reduction of erythromycin and tetracycline resistant heterotrophic bacteria and their resistance genes in municipal wastewater.

    PubMed

    Guo, Mei-Ting; Yuan, Qing-Bin; Yang, Jian

    2013-11-01

    Antibiotic resistance in wastewater is becoming a major public health concern, but poorly understood about impact of disinfection on antibiotic resistant bacteria and antibiotic resistance genes. The UV disinfection of antibiotic resistant heterotrophic bacteria and their relevant genes in the wastewater of a municipal wastewater treatment plant has been evaluated. Two commonly used antibiotics, erythromycin and tetracycline were selected because of their wide occurrences in regard to the antibiotic resistance problem. After UV treatment at a fluence of 5mJcm(-2), the log reductions of heterotrophic bacteria resistant to erythromycin and tetracycline in the wastewater were found to be 1.4±0.1 and 1.1±0.1, respectively. The proportion of tetracycline-resistant bacteria (5%) was nearly double of that before UV disinfection (3%). Tetracycline-resistant bacteria exhibited more tolerance to UV irradiation compared to the erythromycin-resistant bacteria (p<0.05). Gene copy numbers were quantified via qPCR and normalized to the volume of original sample. The total concentrations of erythromycin- and tetracycline-resistance genes were (3.6±0.2)×10(5) and (2.5±0.1)×10(5) copies L(-1), respectively. UV treatment at a fluence of 5mJcm(-2) removed the total erythromycin- and tetracycline-resistance genes by 3.0±0.1 log and 1.9±0.1 log, respectively. UV treatment was effective in reducing antibiotic resistance in the wastewater. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Antibiotic-resistant bacteria: a challenge for the food industry.

    PubMed

    Capita, Rosa; Alonso-Calleja, Carlos

    2013-01-01

    Antibiotic-resistant bacteria were first described in the 1940s, but whereas new antibiotics were being discovered at a steady rate, the consequences of this phenomenon were slow to be appreciated. At present, the paucity of new antimicrobials coming into the market has led to the problem of antibiotic resistance fast escalating into a global health crisis. Although the selective pressure exerted by the use of antibiotics (particularly overuse or misuse) has been deemed the major factor in the emergence of bacterial resistance to these antimicrobials, concerns about the role of the food industry have been growing in recent years and have been raised at both national and international levels. The selective pressure exerted by the use of antibiotics (primary production) and biocides (e.g., disinfectants, food and feed preservatives, or decontaminants) is the main driving force behind the selection and spread of antimicrobial resistance throughout the food chain. Genetically modified (GM) crops with antibiotic resistance marker genes, microorganisms added intentionally to the food chain (probiotic or technological) with potentially transferable antimicrobial resistance genes, and food processing technologies used at sub-lethal doses (e.g., alternative non-thermal treatments) are also issues for concern. This paper presents the main trends in antibiotic resistance and antibiotic development in recent decades, as well as their economic and health consequences, current knowledge concerning the generation, dissemination, and mechanisms of antibacterial resistance, progress to date on the possible routes for emergence of resistance throughout the food chain and the role of foods as a vehicle for antibiotic-resistant bacteria. The main approaches to prevention and control of the development, selection, and spread of antibacterial resistance in the food industry are also addressed.

  5. Epigenetic inheritance based evolution of antibiotic resistance in bacteria

    PubMed Central

    2008-01-01

    Background The evolution of antibiotic resistance in bacteria is a topic of major medical importance. Evolution is the result of natural selection acting on variant phenotypes. Both the rigid base sequence of DNA and the more plastic expression patterns of the genes present define phenotype. Results We investigated the evolution of resistant E. coli when exposed to low concentrations of antibiotic. We show that within an isogenic population there are heritable variations in gene expression patterns, providing phenotypic diversity for antibiotic selection to act on. We studied resistance to three different antibiotics, ampicillin, tetracycline and nalidixic acid, which act by inhibiting cell wall synthesis, protein synthesis and DNA synthesis, respectively. In each case survival rates were too high to be accounted for by spontaneous DNA mutation. In addition, resistance levels could be ramped higher by successive exposures to increasing antibiotic concentrations. Furthermore, reversion rates to antibiotic sensitivity were extremely high, generally over 50%, consistent with an epigenetic inheritance mode of resistance. The gene expression patterns of the antibiotic resistant E. coli were characterized with microarrays. Candidate genes, whose altered expression might confer survival, were tested by driving constitutive overexpression and determining antibiotic resistance. Three categories of resistance genes were identified. The endogenous β-lactamase gene represented a cryptic gene, normally inactive, but when by chance expressed capable of providing potent ampicillin resistance. The glutamate decarboxylase gene, in contrast, is normally expressed, but when overexpressed has the incidental capacity to give an increase in ampicillin resistance. And the DAM methylase gene is capable of regulating the expression of other genes, including multidrug efflux pumps. Conclusion In this report we describe the evolution of antibiotic resistance in bacteria mediated by the

  6. Isolation and characterization of bacteria resistant to metallic copper surfaces.

    PubMed

    Santo, Christophe Espírito; Morais, Paula Vasconcelos; Grass, Gregor

    2010-03-01

    Metallic copper alloys have recently attracted attention as a new antimicrobial weapon for areas where surface hygiene is paramount. Currently it is not understood on a molecular level how metallic copper kills microbes, but previous studies have demonstrated that a wide variety of bacteria, including Escherichia coli, Staphylococcus aureus, and Clostridium difficile, are inactivated within minutes or a few hours of exposure. In this study, we show that bacteria isolated from copper alloy coins comprise strains that are especially resistant against the toxic properties exerted by dry metallic copper surfaces. The most resistant of 294 isolates were Gram-positive staphylococci and micrococci, Kocuria palustris, and Brachybacterium conglomeratum but also included the proteobacterial species Sphingomonas panni and Pseudomonas oleovorans. Cells of some of these bacterial strains survived on copper surfaces for 48 h or more. Remarkably, when these dry-surface-resistant strains were exposed to moist copper surfaces, resistance levels were close to those of control strains and MICs for copper ions were at or below control strain levels. This suggests that mechanisms conferring resistance against dry metallic copper surfaces in these newly isolated bacterial strains are different from well-characterized copper ion detoxification systems. Furthermore, staphylococci on coins did not exhibit increased levels of resistance to antibiotics, arguing against coselection with copper surface resistance traits.

  7. Cadmium transport, resistance, and toxicity in bacteria, algae, and fungi.

    PubMed

    Trevors, J T; Stratton, G W; Gadd, G M

    1986-06-01

    Cadmium is an important environmental pollutant and a potent toxicant to bacteria, algae, and fungi. Mechanisms of Cd toxicity and resistance are variable, depending on the organism. It is very clear that the form of the metal and the environment it is studied in, play an important role in how Cd exerts its effect and how the organism(s) responds. A wide range of Cd concentrations have been used to designate resistance in organisms. To date, no concentration has been specified that is applicable to all species studied under standardized conditions. Cadmium exerts its toxic effect(s) over a wide range of concentrations. In most cases, algae and cyanobacteria are the most sensitive organisms, whereas bacteria and fungi appear to be more resistant. In some bacteria, plasmid-encoded resistance can lead to reduced Cd2+ uptake. However, some Gram-negative bacteria without plasmids are just as resistant to Cd as are bacteria containing plasmids encoding for Cd resistance. According to Silver and Misra (1984), there is no evidence for enzymatic or chemical transformations associated with Cd resistance. Insufficient information is available on the genetics of Cd uptake and resistance in cyanobacteria and algae. Mechanisms remain largely unknown at this point in time. Cadmium is toxic to these organisms, causing severe inhibition of such physiological processes as growth, photosynthesis, and nitrogen fixation at concentrations less than 2 ppm, and often in the ppb range (Tables 2 and 3). Cadmium also causes pronounced morphological aberrations in these organisms, which are probably related to deleterious effects on cell division. This may be direct or indirect, as a result of Cd effects on protein synthesis and cellular organelles such as mitochondria and chloroplasts. Cadmium is accumulated internally in algae (Table 4) as a result of a two-phase uptake process. The first phase involves a rapid physicochemical adsorption of Cd onto cell wall binding sites, which are

  8. Identification and Characterization of Cefotaxime Resistant Bacteria in Beef Cattle

    PubMed Central

    Mir, Raies A.; Weppelmann, Thomas A.; Johnson, Judith A.; Archer, Douglas; Morris, J. Glenn; Jeong, KwangCheol Casey

    2016-01-01

    Third-generation cephalosporins are an important class of antibiotics that are widely used in treatment of serious Gram-negative bacterial infections. In this study, we report the isolation of bacteria resistant to the third-generation cephalosporin cefotaxime from cattle with no previous cefotaxime antibiotic exposure. The prevalence of cefotaxime-resistant bacteria was examined by a combination of culture based and molecular typing methods in beef cattle (n = 1341) from 8 herds located in North Central Florida. The overall prevalence of cefotaxime-resistant bacteria was 15.8% (95% CI: 13.9, 17.8), varied between farms, and ranged from 5.2% to 100%. A subset of isolates (n = 23) was further characterized for the cefotaxime minimum inhibitory concentration (MIC) and antibiotic susceptibility against 10 different antibiotics, sequencing of nine β- lactamase genes, and species identification by 16S rRNA sequencing. Most of the bacterial isolates were resistant to cefotaxime (concentrations, > 64 μg/mL) and showed high levels of multi-drug resistance. Full length 16S rRNA sequences (~1300 bp) revealed that most of the isolates were not primary human or animal pathogens; rather were more typical of commensal, soil, or other environmental origin. Six extended spectrum β-lactamase (ESBL) genes identical to those in clinical human isolates were identified. Our study highlights the potential for carriage of cefotaxime resistance (including “human” ESBL genes) by the bacterial flora of food animals with no history of cefotaxime antibiotic exposure. A better understanding of the origin and transmission of resistance genes in these pre-harvest settings will be critical to development of strategies to prevent the spread of antimicrobial resistant microorganisms to hospitals and communities. PMID:27642751

  9. Identification and Characterization of Cefotaxime Resistant Bacteria in Beef Cattle.

    PubMed

    Mir, Raies A; Weppelmann, Thomas A; Johnson, Judith A; Archer, Douglas; Morris, J Glenn; Jeong, KwangCheol Casey

    2016-01-01

    Third-generation cephalosporins are an important class of antibiotics that are widely used in treatment of serious Gram-negative bacterial infections. In this study, we report the isolation of bacteria resistant to the third-generation cephalosporin cefotaxime from cattle with no previous cefotaxime antibiotic exposure. The prevalence of cefotaxime-resistant bacteria was examined by a combination of culture based and molecular typing methods in beef cattle (n = 1341) from 8 herds located in North Central Florida. The overall prevalence of cefotaxime-resistant bacteria was 15.8% (95% CI: 13.9, 17.8), varied between farms, and ranged from 5.2% to 100%. A subset of isolates (n = 23) was further characterized for the cefotaxime minimum inhibitory concentration (MIC) and antibiotic susceptibility against 10 different antibiotics, sequencing of nine β- lactamase genes, and species identification by 16S rRNA sequencing. Most of the bacterial isolates were resistant to cefotaxime (concentrations, > 64 μg/mL) and showed high levels of multi-drug resistance. Full length 16S rRNA sequences (~1300 bp) revealed that most of the isolates were not primary human or animal pathogens; rather were more typical of commensal, soil, or other environmental origin. Six extended spectrum β-lactamase (ESBL) genes identical to those in clinical human isolates were identified. Our study highlights the potential for carriage of cefotaxime resistance (including "human" ESBL genes) by the bacterial flora of food animals with no history of cefotaxime antibiotic exposure. A better understanding of the origin and transmission of resistance genes in these pre-harvest settings will be critical to development of strategies to prevent the spread of antimicrobial resistant microorganisms to hospitals and communities.

  10. Fate of Antibiotic Resistant Bacteria and Genes during Wastewater Chlorination: Implication for Antibiotic Resistance Control

    PubMed Central

    Yuan, Qing-Bin; Guo, Mei-Ting; Yang, Jian

    2015-01-01

    This study investigated fates of nine antibiotic-resistant bacteria as well as two series of antibiotic resistance genes in wastewater treated by various doses of chlorine (0, 15, 30, 60, 150 and 300 mg Cl2 min/L). The results indicated that chlorination was effective in inactivating antibiotic-resistant bacteria. Most bacteria were inactivated completely at the lowest dose (15 mg Cl2 min/L). By comparison, sulfadiazine- and erythromycin-resistant bacteria exhibited tolerance to low chlorine dose (up to 60 mg Cl2 min/L). However, quantitative real-time PCRs revealed that chlorination decreased limited erythromycin or tetracycline resistance genes, with the removal levels of overall erythromycin and tetracycline resistance genes at 0.42 ± 0.12 log and 0.10 ± 0.02 log, respectively. About 40% of erythromycin-resistance genes and 80% of tetracycline resistance genes could not be removed by chlorination. Chlorination was considered not effective in controlling antimicrobial resistance. More concern needs to be paid to the potential risk of antibiotic resistance genes in the wastewater after chlorination. PMID:25738838

  11. Fate of antibiotic resistant bacteria and genes during wastewater chlorination: implication for antibiotic resistance control.

    PubMed

    Yuan, Qing-Bin; Guo, Mei-Ting; Yang, Jian

    2015-01-01

    This study investigated fates of nine antibiotic-resistant bacteria as well as two series of antibiotic resistance genes in wastewater treated by various doses of chlorine (0, 15, 30, 60, 150 and 300 mg Cl2 min/L). The results indicated that chlorination was effective in inactivating antibiotic-resistant bacteria. Most bacteria were inactivated completely at the lowest dose (15 mg Cl2 min/L). By comparison, sulfadiazine- and erythromycin-resistant bacteria exhibited tolerance to low chlorine dose (up to 60 mg Cl2 min/L). However, quantitative real-time PCRs revealed that chlorination decreased limited erythromycin or tetracycline resistance genes, with the removal levels of overall erythromycin and tetracycline resistance genes at 0.42 ± 0.12 log and 0.10 ± 0.02 log, respectively. About 40% of erythromycin-resistance genes and 80% of tetracycline resistance genes could not be removed by chlorination. Chlorination was considered not effective in controlling antimicrobial resistance. More concern needs to be paid to the potential risk of antibiotic resistance genes in the wastewater after chlorination.

  12. Isolation and characterization of chromate resistant bacteria from tannery effluent.

    PubMed

    Shukla, O P; Rai, U N; Singh, N K; Dubey, Smita; Baghel, V S

    2007-04-01

    The tannery effluent emanating from Common Effluent Treatment Plant (CETP), Unnao (U.P, India) was found toxic in nature, having high BOD, COD, TDS and Cr content (5.88 mg l(-1)), which supported growth of chromate tolerant bacteria. Several chromate tolerant bacteria have been isolated from these effluent and maximum tolerant four strains (NBRIP-1, NBRIP-2, NBRIP-3 and NBRIP-4) were characterized in this study. These strains showed multiple metal and antibiotic resistances. Growth of these strains was reduced at higher Cr concentration with extention of lag phase. Chromium accumlulation by these isolates may have a great potential in recovery and detoxification of Cr from tannery effluent.

  13. Antibiotic resistance of lactic acid bacteria isolated from Chinese yogurts.

    PubMed

    Zhou, N; Zhang, J X; Fan, M T; Wang, J; Guo, G; Wei, X Y

    2012-09-01

    The aim of this study was to evaluate the susceptibility of 43 strains of lactic acid bacteria, isolated from Chinese yogurts made in different geographical areas, to 11 antibiotics (ampicillin, penicillin G, roxithromycin, chloramphenicol, tetracycline, chlortetracycline, lincomycin, kanamycin, streptomycin, neomycin, and gentamycin). The 43 isolates (18 Lactobacillus bulgaricus and 25 Streptococcus thermophilus) were identified at species level and were typed by random amplified polymorphic DNA analysis. Thirty-five genotypically different strains were detected and their antimicrobial resistance to 11 antibiotics was determined using the agar dilution method. Widespread resistance to ampicillin, chloramphenicol, chlortetracycline, tetracyclines, lincomycin, streptomycin, neomycin, and gentamycin was found among the 35 strains tested. All of the Strep. thermophilus strains tested were susceptible to penicillin G and roxithromycin, whereas 23.5 and 64.7% of Lb. bulgaricus strains, respectively, were resistant. All of the Strep. thermophilus and Lb. bulgaricus strains were found to be resistant to kanamycin. The presence of the corresponding resistance genes in the resistant isolates was investigated through PCR, with the following genes detected: tet(M) in 1 Lb. bulgaricus and 2 Strep. thermophilus isolates, ant(6) in 2 Lb. bulgaricus and 2 Strep. thermophilus isolates, and aph(3')-IIIa in 5 Lb. bulgaricus and 2 Strep. thermophilus isolates. The main threat associated with these bacteria is that they may transfer resistance genes to pathogenic bacteria, which has been a major cause of concern to human and animal health. To our knowledge, the aph(3')-IIIa and ant(6) genes were found in Lb. bulgaricus and Strep. thermophilus for the first time. Further investigations are required to analyze whether the genes identified in Lb. bulgaricus and Strep. thermophilus isolates might be horizontally transferred to other species. Copyright © 2012 American Dairy Science

  14. Monitoring of antimicrobial resistance in pathogenic bacteria from livestock animals.

    PubMed

    Wallmann, Jürgen

    2006-06-01

    Facing the problem of development and spreading of bacterial resistance, preventive strategies are considered the most appropriate means to counteract. The establishment of corresponding management options relies on scientifically defensible efforts to obtain objective data on the prevalence of bacterial resistance in healthy and diseased livestock. Additionally, detailed statistics are needed on the overall amount of antimicrobial agents dispensed in Germany. The collection of valid data on the prevalence of resistance requires representative and cross-sectional studies. The German national antimicrobial resistance monitoring of the Federal Office of Consumer Protection and Food Safety (BVL) determines the current quantitative resistance level of life-stock pathogens, in order to permit the evaluation and surveillance of the distribution of resistances on a valid basis. Essential key features determining the design of these studies comprise (1) a statistically valid sampling program. This incorporates regional differences in animal population density, (2) the avoidance of "copy strains", (3) testing of no more than two bacterial strains belonging to one species per herd, (4) testing only if no antimicrobial therapy preceded sample collection, and (5) the use of standardized methods [e.g. microdilution broth method to determine the minimal inhibitory concentration (MIC)]. The analysis and interpretation of this data permits reliable identification and definition of epidemiological characteristics of resistance and its development in animal associated bacteria, such as geographically and time wise differentiated profiles on its prevalence, the emergence of unknown phenotypes of resistance and an assessment of the threat resistant bacteria from animals pose for humans. In applied antimicrobial therapy, the data can serve as a decision guidance in choosing the antimicrobial agent most adapted to the prevailing epidemiological situation. The susceptibility testing

  15. 1 in 4 Nursing Home Residents Has Antibiotic-Resistant Bacteria

    MedlinePlus

    ... in 4 Nursing Home Residents Has Antibiotic-Resistant Bacteria More infection-prevention education and policies are needed, ... TUESDAY, May 30, 2017 (HealthDay News) -- Multidrug-resistant bacteria, such as E. coli , can be found in ...

  16. “Infectious Supercarelessness” in Discussing Antibiotic-Resistant Bacteria

    PubMed Central

    Greenspan, Neil S.

    2017-01-01

    Many bacterial pathogens are exhibiting resistance to increasing numbers of antibiotics making it much more challenging to treat the infections caused by these microbes. In many reports in the media and perhaps even in discussions among physicians and biomedical scientists, these bacteria are frequently referred to as “bugs” with the prefix “super” appended. This terminology has a high potential to elicit unjustified inferences and fails to highlight the broader evolutionary context. Understanding the full range of biological and evolutionary factors that influence the spread and outcomes of infections is critical to formulating effective individual therapies and public health interventions. Therefore, more accurate terminology should be used to refer these multidrug-resistant bacteria. PMID:28174759

  17. Bacteria-bacteria interactions within the microbiota of the ancestral metazoan Hydra contribute to fungal resistance.

    PubMed

    Fraune, Sebastian; Anton-Erxleben, Friederike; Augustin, René; Franzenburg, Sören; Knop, Mirjam; Schröder, Katja; Willoweit-Ohl, Doris; Bosch, Thomas C G

    2015-07-01

    Epithelial surfaces of most animals are colonized by diverse microbial communities. Although it is generally agreed that commensal bacteria can serve beneficial functions, the processes involved are poorly understood. Here we report that in the basal metazoan Hydra, ectodermal epithelial cells are covered with a multilayered glycocalyx that provides a habitat for a distinctive microbial community. Removing this epithelial microbiota results in lethal infection by the filamentous fungus Fusarium sp. Restoring the complex microbiota in gnotobiotic polyps prevents pathogen infection. Although mono-associations with distinct members of the microbiota fail to provide full protection, additive and synergistic interactions of commensal bacteria are contributing to full fungal resistance. Our results highlight the importance of resident microbiota diversity as a protective factor against pathogen infections. Besides revealing insights into the in vivo function of commensal microbes in Hydra, our findings indicate that interactions among commensal bacteria are essential to inhibit pathogen infection.

  18. [Antibiotic-resistant bacteria and new directions of antimicrobial chemotherapy].

    PubMed

    Tateda, Kazuhiro

    2012-05-01

    The emergence and spread of antibiotic-resistant organisms are becoming more and more serious and are a worldwide problem. Recent trends in new antibiotic-resistant organisms include multiple-drug resistant Pseudomonas aeruginosa (MDRP), MDR-Acinetobacter baumannii (MDR-AB) and New Deli metallo beta-lactamase-1 (NDM-1) -producing bacteria. Antibiotic combination therapy is an option to overcome these MDR organisms. A breakpoint checkerboard plate was created to measure antibiotic combination effects at breakpoint concentrations, making it possible to evaluate the synergy of antibiotic combination within 24 hours. In this article, recent topics regarding antibiotic-resistant organisms are briefly reviewed and the directions of antibiotic chemotherapy against these organisms are discussed.

  19. Combination Approaches to Combat Multi-Drug Resistant Bacteria

    PubMed Central

    Worthington, Roberta J.; Melander, Christian

    2013-01-01

    The increasing prevalence of infections caused by multi-drug resistant bacteria is a global health problem that is exacerbated by the dearth of novel classes of antibiotics entering the clinic over the past 40 years. Herein we describe recent developments toward combination therapies for the treatment of multi-drug resistant bacterial infections. These efforts include antibiotic-antibiotic combinations, and the development of adjuvants that either directly target resistance mechanisms such as the inhibition of β-lactamase enzymes, or indirectly target resistance by interfering with bacterial signaling pathways such as two-component systems. We also discuss screening of libraries of previously approved drugs to identify non-obvious antimicrobial adjuvants. PMID:23333434

  20. Antibacterial clay against gram-negative antibiotic resistant bacteria.

    PubMed

    Zarate-Reyes, Luis; Lopez-Pacheco, Cynthia; Nieto-Camacho, Antonio; Palacios, Eduardo; Gómez-Vidales, Virginia; Kaufhold, Stephan; Ufer, Kristian; García Zepeda, Eduardo; Cervini-Silva, Javiera

    2017-09-01

    Antibiotic resistant bacteria persist throughout the world because they have evolved the ability to express various defense mechanisms to cope with antibiotics and the immune system; thus, low-cost strategies for the treatment of these bacteria are needed, such as the usage of environmental minerals. This paper reports the antimicrobial properties of a clay collected from Brunnenberg, Germany, that is composed of ferroan saponite with admixtures of quartz, feldspar and calcite as well as exposed or hidden (layered at inner regions) nano Fe(0). Based on the growth curves (log phase) of six antibiotic resistant bacteria (4 gram-negative and 2 gram-positive), we concluded that the clay acted as a bacteriostat; however, the clay was only active against the gram-negative bacteria (except for resilient Klebsiella pneumonia). The bacteriostatic mode of action was evidenced by the initial lack of Colony Forming Units on agar plates with growth registered afterward, certainly after 24h, and can be explained because interactions between membrane lipopolysaccharides and the siloxane surfaces of the clay. Labile or bioavailable Fe in the clay (extracted by EDTA or DFO-B) induced the quantitative production of HO as well as oxidative stress, which, nevertheless, did not account for by its bacteriostatic activity. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Identification of vancomycin-resistant lactic bacteria isolated from humans.

    PubMed Central

    Mackey, T; Lejeune, V; Janssens, M; Wauters, G

    1993-01-01

    By using cell morphology, arginine dihydrolase, and gas production in de Man, Sharp, Rogosa broth, 122 isolates of vancomycin-resistant lactic bacteria from humans were assigned to five profiles, allowing us to distinguish Pediococcus, homofermentative and heterofermentative Lactobacillus, and Leuconostoc species. The absence of L-(+)-lactic acid, as detected spectrophotometrically, was confirmatory for Leuconostoc species. API 50 CHL panels were useful for the identification of Lactobacillus species. PMID:8408575

  2. Metagenomic Insights into Transferable Antibiotic Resistance in Oral Bacteria.

    PubMed

    Sukumar, S; Roberts, A P; Martin, F E; Adler, C J

    2016-08-01

    Antibiotic resistance is considered one of the greatest threats to global public health. Resistance is often conferred by the presence of antibiotic resistance genes (ARGs), which are readily found in the oral microbiome. In-depth genetic analyses of the oral microbiome through metagenomic techniques reveal a broad distribution of ARGs (including novel ARGs) in individuals not recently exposed to antibiotics, including humans in isolated indigenous populations. This has resulted in a paradigm shift from focusing on the carriage of antibiotic resistance in pathogenic bacteria to a broader concept of an oral resistome, which includes all resistance genes in the microbiome. Metagenomics is beginning to demonstrate the role of the oral resistome and horizontal gene transfer within and between commensals in the absence of selective pressure, such as an antibiotic. At the chairside, metagenomic data reinforce our need to adhere to current antibiotic guidelines to minimize the spread of resistance, as such data reveal the extent of ARGs without exposure to antimicrobials and the ecologic changes created in the oral microbiome by even a single dose of antibiotics. The aim of this review is to discuss the role of metagenomics in the investigation of the oral resistome, including the transmission of antibiotic resistance in the oral microbiome. Future perspectives, including clinical implications of the findings from metagenomic investigations of oral ARGs, are also considered. © International & American Associations for Dental Research 2016.

  3. Resistance to bacteriocins produced by Gram-positive bacteria.

    PubMed

    Bastos, Maria do Carmo de Freire; Coelho, Marcus Lívio Varella; Santos, Olinda Cabral da Silva

    2015-04-01

    Bacteriocins are prokaryotic proteins or peptides with antimicrobial activity. Most of them exhibit a broad spectrum of activity, inhibiting micro-organisms belonging to different genera and species, including many bacterial pathogens which cause human, animal or plant infections. Therefore, these substances have potential biotechnological applications in either food preservation or prevention and control of bacterial infectious diseases. However, there is concern that continuous exposure of bacteria to bacteriocins may select cells resistant to them, as observed for conventional antimicrobials. Based on the models already investigated, bacteriocin resistance may be either innate or acquired and seems to be a complex phenomenon, arising at different frequencies (generally from 10(-9) to 10(-2)) and by different mechanisms, even amongst strains of the same bacterial species. In the present review, we discuss the prevalence, development and molecular mechanisms involved in resistance to bacteriocins produced by Gram-positive bacteria. These mechanisms generally involve changes in the bacterial cell envelope, which result in (i) reduction or loss of bacteriocin binding or insertion, (ii) bacteriocin sequestering, (iii) bacteriocin efflux pumping (export) and (iv) bacteriocin degradation, amongst others. Strategies that can be used to overcome this resistance are also addressed.

  4. Determinants of Genetic Diversity of Spontaneous Drug Resistance in Bacteria

    PubMed Central

    Couce, Alejandro; Rodríguez-Rojas, Alexandro; Blázquez, Jesús

    2016-01-01

    Any pathogen population sufficiently large is expected to harbor spontaneous drug-resistant mutants, often responsible for disease relapse after antibiotic therapy. It is seldom appreciated, however, that while larger populations harbor more mutants, the abundance distribution of these mutants is expected to be markedly uneven. This is because a larger population size allows early mutants to expand for longer, exacerbating their predominance in the final mutant subpopulation. Here, we investigate the extent to which this reduction in evenness can constrain the genetic diversity of spontaneous drug resistance in bacteria. Combining theory and experiments, we show that even small variations in growth rate between resistant mutants and the wild type result in orders-of-magnitude differences in genetic diversity. Indeed, only a slight fitness advantage for the mutant is enough to keep diversity low and independent of population size. These results have important clinical implications. Genetic diversity at antibiotic resistance loci can determine a population’s capacity to cope with future challenges (i.e., second-line therapy). We thus revealed an unanticipated way in which the fitness effects of antibiotic resistance can affect the evolvability of pathogens surviving a drug-induced bottleneck. This insight will assist in the fight against multidrug-resistant microbes, as well as contribute to theories aimed at predicting cancer evolution. PMID:27182949

  5. Determinants of Genetic Diversity of Spontaneous Drug Resistance in Bacteria.

    PubMed

    Couce, Alejandro; Rodríguez-Rojas, Alexandro; Blázquez, Jesús

    2016-07-01

    Any pathogen population sufficiently large is expected to harbor spontaneous drug-resistant mutants, often responsible for disease relapse after antibiotic therapy. It is seldom appreciated, however, that while larger populations harbor more mutants, the abundance distribution of these mutants is expected to be markedly uneven. This is because a larger population size allows early mutants to expand for longer, exacerbating their predominance in the final mutant subpopulation. Here, we investigate the extent to which this reduction in evenness can constrain the genetic diversity of spontaneous drug resistance in bacteria. Combining theory and experiments, we show that even small variations in growth rate between resistant mutants and the wild type result in orders-of-magnitude differences in genetic diversity. Indeed, only a slight fitness advantage for the mutant is enough to keep diversity low and independent of population size. These results have important clinical implications. Genetic diversity at antibiotic resistance loci can determine a population's capacity to cope with future challenges (i.e., second-line therapy). We thus revealed an unanticipated way in which the fitness effects of antibiotic resistance can affect the evolvability of pathogens surviving a drug-induced bottleneck. This insight will assist in the fight against multidrug-resistant microbes, as well as contribute to theories aimed at predicting cancer evolution. Copyright © 2016 by the Genetics Society of America.

  6. Antibiotic resistance: What is so special about multidrug-resistant Gram-negative bacteria?

    PubMed Central

    Exner, Martin; Bhattacharya, Sanjay; Christiansen, Bärbel; Gebel, Jürgen; Goroncy-Bermes, Peter; Hartemann, Philippe; Heeg, Peter; Ilschner, Carola; Kramer, Axel; Larson, Elaine; Merkens, Wolfgang; Mielke, Martin; Oltmanns, Peter; Ross, Birgit; Rotter, Manfred; Schmithausen, Ricarda Maria; Sonntag, Hans-Günther; Trautmann, Matthias

    2017-01-01

    In the past years infections caused by multidrug-resistant Gram-negative bacteria have dramatically increased in all parts of the world. This consensus paper is based on presentations, subsequent discussions and an appraisal of current literature by a panel of international experts invited by the Rudolf Schülke Stiftung, Hamburg. It deals with the epidemiology and the inherent properties of Gram-negative bacteria, elucidating the patterns of the spread of antibiotic resistance, highlighting reservoirs as well as transmission pathways and risk factors for infection, mortality, treatment and prevention options as well as the consequences of their prevalence in livestock. Following a global, One Health approach and based on the evaluation of the existing knowledge about these pathogens, this paper gives recommendations for prevention and infection control measures as well as proposals for various target groups to tackle the threats posed by Gram-negative bacteria and prevent the spread and emergence of new antibiotic resistances. PMID:28451516

  7. Heavy metal resistance in halophilic Bacteria and Archaea.

    PubMed

    Voica, Doriana Mădălina; Bartha, Laszlo; Banciu, Horia Leonard; Oren, Aharon

    2016-07-01

    Heavy metals are dense chemicals with dual biological role as micronutrients and intoxicants. A few hypersaline environmental systems are naturally enriched with heavy metals, while most metal-contaminated sites are a consequence of human activities. Numerous halotolerant and moderately halophilic Bacteria possess metal tolerance, whereas a few archaeal counterparts share similar features. The main mechanisms underlying heavy metal resistance in halophilic Bacteria and Archaea include extracellular metal sequestration by biopolymers, metal efflux mediated by specific transporters and enzymatic detoxification. Biotransformation of metals by halophiles has implications both for trace metal turnover in natural saline ecosystems and for development of novel bioremediation strategies. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Antibiotic resistance shaping multi-level population biology of bacteria

    PubMed Central

    Baquero, Fernando; Tedim, Ana P.; Coque, Teresa M.

    2013-01-01

    Antibiotics have natural functions, mostly involving cell-to-cell signaling networks. The anthropogenic production of antibiotics, and its release in the microbiosphere results in a disturbance of these networks, antibiotic resistance tending to preserve its integrity. The cost of such adaptation is the emergence and dissemination of antibiotic resistance genes, and of all genetic and cellular vehicles in which these genes are located. Selection of the combinations of the different evolutionary units (genes, integrons, transposons, plasmids, cells, communities and microbiomes, hosts) is highly asymmetrical. Each unit of selection is a self-interested entity, exploiting the higher hierarchical unit for its own benefit, but in doing so the higher hierarchical unit might acquire critical traits for its spread because of the exploitation of the lower hierarchical unit. This interactive trade-off shapes the population biology of antibiotic resistance, a composed-complex array of the independent “population biologies.” Antibiotics modify the abundance and the interactive field of each of these units. Antibiotics increase the number and evolvability of “clinical” antibiotic resistance genes, but probably also many other genes with different primary functions but with a resistance phenotype present in the environmental resistome. Antibiotics influence the abundance, modularity, and spread of integrons, transposons, and plasmids, mostly acting on structures present before the antibiotic era. Antibiotics enrich particular bacterial lineages and clones and contribute to local clonalization processes. Antibiotics amplify particular genetic exchange communities sharing antibiotic resistance genes and platforms within microbiomes. In particular human or animal hosts, the microbiomic composition might facilitate the interactions between evolutionary units involved in antibiotic resistance. The understanding of antibiotic resistance implies expanding our knowledge on multi

  9. Antibiotic resistance shaping multi-level population biology of bacteria.

    PubMed

    Baquero, Fernando; Tedim, Ana P; Coque, Teresa M

    2013-01-01

    Antibiotics have natural functions, mostly involving cell-to-cell signaling networks. The anthropogenic production of antibiotics, and its release in the microbiosphere results in a disturbance of these networks, antibiotic resistance tending to preserve its integrity. The cost of such adaptation is the emergence and dissemination of antibiotic resistance genes, and of all genetic and cellular vehicles in which these genes are located. Selection of the combinations of the different evolutionary units (genes, integrons, transposons, plasmids, cells, communities and microbiomes, hosts) is highly asymmetrical. Each unit of selection is a self-interested entity, exploiting the higher hierarchical unit for its own benefit, but in doing so the higher hierarchical unit might acquire critical traits for its spread because of the exploitation of the lower hierarchical unit. This interactive trade-off shapes the population biology of antibiotic resistance, a composed-complex array of the independent "population biologies." Antibiotics modify the abundance and the interactive field of each of these units. Antibiotics increase the number and evolvability of "clinical" antibiotic resistance genes, but probably also many other genes with different primary functions but with a resistance phenotype present in the environmental resistome. Antibiotics influence the abundance, modularity, and spread of integrons, transposons, and plasmids, mostly acting on structures present before the antibiotic era. Antibiotics enrich particular bacterial lineages and clones and contribute to local clonalization processes. Antibiotics amplify particular genetic exchange communities sharing antibiotic resistance genes and platforms within microbiomes. In particular human or animal hosts, the microbiomic composition might facilitate the interactions between evolutionary units involved in antibiotic resistance. The understanding of antibiotic resistance implies expanding our knowledge on multi

  10. Colistin use and colistin resistance in bacteria from animals.

    PubMed

    Kempf, Isabelle; Jouy, Eric; Chauvin, Claire

    2016-12-01

    Colistin has been used in veterinary medicine for decades, mainly for the prevention and treatment of Enterobacteriaceae infections. However, data regarding colistin resistance in bacteria from animals and food of animal origin are relatively scarce, partly because there are methodological difficulties hampering the analysis of susceptibility to colistin. Most data regarding clinical isolates are related to enteropathogenic Escherichia coli and Salmonella. The resistance percentages are sometimes high for pathogenic strains, and the mcr-1 gene has been detected in pathogenic E. coli isolates from pigs, cattle and poultry in different countries. The prevalence of colistin resistance in Salmonella from healthy animals is usually low but depends on the proportion of intrinsically colistin-resistant serotypes. For indicator E. coli, the resistance levels are often very low, although higher levels have been observed in Asia. The mcr-1 gene has been detected in indicator E. coli from pigs, cattle, poultry and their products. Thus, there is an urgent need to re-assess the use of colistin in livestock throughout the world to ensure a global strategy for preserving this last-resort antimicrobial.

  11. Lead resistant bacteria: lead resistance mechanisms, their applications in lead bioremediation and biomonitoring.

    PubMed

    Naik, Milind Mohan; Dubey, Santosh Kumar

    2013-12-01

    Lead (Pb) is non-bioessential, persistent and hazardous heavy metal pollutant of environmental concern. Bioremediation has become a potential alternative to the existing technologies for the removal and/or recovery of toxic lead from waste waters before releasing it into natural water bodies for environmental safety. To our best knowledge, this is a first review presenting different mechanisms employed by lead resistant bacteria to resist high levels of lead and their applications in cost effective and eco-friendly ways of lead bioremediation and biomonitoring. Various lead resistant mechanisms employed by lead resistant bacteria includes efflux mechanism, extracellular sequestration, biosorption, precipitation, alteration in cell morphology, enhanced siderophore production and intracellular lead bioaccumulation.

  12. Fate of antibiotic resistant cultivable heterotrophic bacteria and antibiotic resistance genes in wastewater treatment processes.

    PubMed

    Zhang, Songhe; Han, Bing; Gu, Ju; Wang, Chao; Wang, Peifang; Ma, Yanyan; Cao, Jiashun; He, Zhenli

    2015-09-01

    Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are emerging contaminants of environmental concern. Heterotrophic bacteria in activated sludge have an important role in wastewater treatment plants (WWTPs). However, the fate of cultivable heterotrophic ARB and ARGs in WWPTs process remains unclear. In the present study, we investigated the antibiotic-resistant phenotypes of cultivable heterotrophic bacteria from influent and effluent water of three WWTPs and analysed thirteen ARGs in ARB and in activated sludge from anoxic, anaerobic and aerobic compartments. From each influent or effluent sample of the three plants, 200 isolates were randomly tested for susceptibility to 12 antibiotics. In these samples, between 5% and 64% isolates showed resistance to >9 antibiotics and the proportion of >9-drug-resistant bacteria was lower in isolates from effluent than from influent. Eighteen genera were identified in 188 isolates from influent (n=94) and effluent (n=94) of one WWTP. Six genera (Aeromonas, Bacillus, Lysinibacillus, Microbacterium, Providencia, and Staphylococcus) were detected in both influent and effluent samples. Gram-negative and -positive isolates dominated in influent and effluent, respectively. The 13 tetracycline-, sulphonamide-, streptomycin- and β-lactam-resistance genes were detected at a higher frequency in ARB from influent than from effluent, except for sulA and CTX-M, while in general, the abundances of ARGs in activated sludge from two of the three plants were higher in aerobic compartments than in anoxic ones, indicating abundant ARGs exit in the excess sledges and/or in uncultivable bacteria. These findings may be useful for elucidating the effect of WWTP on ARB and ARGs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Vaccines for Antibiotic-Resistant Bacteria: Possibility or Pipe Dream?

    PubMed

    García-Quintanilla, Meritxell; Pulido, Marina R; Carretero-Ledesma, Marta; McConnell, Michael J

    2016-02-01

    The increasing incidence of infections caused by antibiotic-resistant bacteria from multiple species, together with the paucity of new antibiotics in the development pipeline, indicates that vaccines could play a role in combating these infections. The development of vaccines for these infections presents unique challenges related to target population selection, vaccine administration, and antigen identification. Advances in genomic, transcriptomic, and proteomic technologies offer great potential for identifying promising antigens that are highly conserved and expressed during human infections. Although important challenges remain, the potential health and economic benefits associated with the clinical implementation of vaccination strategies for the prevention of antibiotic-resistant infections warrant their continued development. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Progress in engineering acid stress resistance of lactic acid bacteria.

    PubMed

    Wu, Chongde; Huang, Jun; Zhou, Rongqing

    2014-02-01

    Lactic acid bacteria (LAB) are widely used for the production of a variety of fermented foods, and are considered as probiotic due to their health-promoting effect. However, LAB encounter various environmental stresses both in industrial fermentation and application, among which acid stress is one of the most important survival challenges. Improving the acid stress resistance may contribute to the application and function of probiotic action to the host. Recently, the advent of genomics, functional genomics and high-throughput technologies have allowed for the understanding of acid tolerance mechanisms at a systems level, and many method to improve acid tolerance have been developed. This review describes the current progress in engineering acid stress resistance of LAB. Special emphasis is placed on engineering cellular microenvironment (engineering amino acid metabolism, introduction of exogenous biosynthetic capacity, and overproduction of stress response proteins) and maintaining cell membrane functionality. Moreover, strategies to improve acid tolerance and the related physiological mechanisms are also discussed.

  15. Detection of antibiotic resistant bacteria inhabiting the sand of non-recreational marine beach.

    PubMed

    Mudryk, Zbigniew; Perliński, Piotr; Skórczewski, Piotr

    2010-02-01

    The present study examined the antibiotic resistance of heterotrophic bacteria, which were isolated from the sand of the beach located in the National Park of the southern Baltic Sea coast. The bacteria demonstrated low levels of antibiotic resistance. These microorganisms were the most resistant to cefaclor and clindamycin and the most sensitive to clarithromycin, doxycycline, gentamycin and oxytetracycline. The majority of bacteria inhabiting the sand of the studied beach were resistant to only one antibiotic out of 18 tested antibiotics in this study. The bacteria inhabiting the middle part of the beach and the dune were more antibiotic resistant than bacteria isolated from the seawater and the shoreline-seawater contact zone. Generally, there was no significant difference in antibiotic resistance between bacteria isolated from the surface and the subsurface sand layers. The bacterial antibiotic resistance level depends on the chemical structure of antibiotics.

  16. Mobile antibiotic resistance - the spread of genes determining the resistance of bacteria through food products.

    PubMed

    Godziszewska, Jolanta; Guzek, Dominika; Głąbski, Krzysztof; Wierzbicka, Agnieszka

    2016-07-07

    In recent years, more and more antibiotics have become ineffective in the treatment of bacterial nfections. The acquisition of antibiotic resistance by bacteria is associated with circulation of genes in the environment. Determinants of antibiotic resistance may be transferred to pathogenic bacteria. It has been shown that conjugation is one of the key mechanisms responsible for spread of antibiotic resistance genes, which is highly efficient and allows the barrier to restrictions and modifications to be avoided. Some conjugative modules enable the transfer of plasmids even between phylogenetically distant bacterial species. Many scientific reports indicate that food is one of the main reservoirs of these genes. Antibiotic resistance genes have been identified in meat products, milk, fruits and vegetables. The reason for such a wide spread of antibiotic resistance genes is the overuse of antibiotics by breeders of plants and animals, as well as by horizontal gene transfer. It was shown, that resistance determinants located on mobile genetic elements, which are isolated from food products, can easily be transferred to another niche. The antibiotic resistance genes have been in the environment for 30 000 years. Their removal from food products is not possible, but the risks associated with the emergence of multiresistant pathogenic strains are very large. The only option is to control the emergence, selection and spread of these genes. Therefore measures are sought to prevent horizontal transfer of genes. Promising concepts involve the combination of developmental biology, evolution and ecology in the fight against the spread of antibiotic resistance.

  17. Searching for novel photolyases in UVC-resistant Antarctic bacteria.

    PubMed

    Marizcurrena, Juan José; Morel, María A; Braña, Victoria; Morales, Danilo; Martinez-López, Wilner; Castro-Sowinski, Susana

    2017-03-01

    Ultraviolet (UV) light irradiation has serious consequences for cell survival, including DNA damage by formation of cyclobutane pyrimidine dimers (CPD) and pyrimidine (6,4) pyrimidone photoproducts. In general, the Nucleotide Excision Repair pathway repairs these lesions; however, all living forms, except placental mammals and some marsupials, produce a flavoprotein known as photolyase that directly reverses these lesions. The aim of this work was the isolation and identification of Antarctic UVC-resistant bacteria, and the search for novel photolyases. Two Antarctic water samples were UVC-irradiated (254 nm; 50-200 J m(- 2)) and 12 UVC-resistant bacteria were isolated and identified by 16S rDNA amplification/analysis as members of the genera Pseudomonas, Janthinobacterium, Flavobacterium, Hymenobacter and Sphingomonas. The UVC 50% lethal dose and the photo-repair ability of isolates were analyzed. The occurrence of photolyase coding sequences in Pseudomonas, Hymenobacter and Sphingomonas isolates were searched by PCR or by searching in the draft DNA genome. Results suggest that Pseudomonas and Hymenobacter isolates produce CDP-photolyases, and Sphingomonas produces two CPD-photolyases and a 6,4-photolyase. Results suggest that the Antarctic environment is an important source of genetic material for the identification of novel photolyase genes with potential biotechnological applications.

  18. Alternative periplasmic copper-resistance mechanisms in Gram negative bacteria.

    PubMed

    Pontel, Lucas B; Soncini, Fernando C

    2009-07-01

    Bacteria have evolved different systems to tightly control both cytosolic and envelope copper concentration to fulfil their requirements and at the same time, avoid copper toxicity. We have previously demonstrated that, as in Escherichia coli, the Salmonella cue system protects the cytosol from copper excess. On the other hand, and even though Salmonella lacks the CusCFBA periplasmic copper efflux system, it can support higher copper concentrations than E. coli under anaerobic conditions. Here we show that the Salmonella cue regulon is also responsible for the control of copper toxicity in anaerobiosis. We establish that resistance in this condition requires a novel CueR-controlled gene named cueP. A DeltacueP mutant is highly susceptible to copper in the absence of oxygen, but shows a faint phenotype in aerobic conditions unless other copper-resistance genes are also deleted, resembling the E. coli CusCFBA behaviour. Species that contain a cueP homologue under CueR regulation have no functional CusR/CusS-dependent Cus-coding operon. Conversely, species that carry a CusR/CusS-regulated cus operon have no cueP homologues. Even more, we show that the CueR-controlled cueP expression increases copper resistance of a Deltacus E. coli. We posit that CueP can functionally replace the Cus complex for periplasmic copper resistance, in particular under anaerobic conditions.

  19. A Functional Metagenomic Analysis of Tetracycline Resistance in Cheese Bacteria

    PubMed Central

    Flórez, Ana B.; Vázquez, Lucía; Mayo, Baltasar

    2017-01-01

    Metagenomic techniques have been successfully used to monitor antibiotic resistance genes in environmental, animal and human ecosystems. However, despite the claim that the food chain plays a key role in the spread of antibiotic resistance, metagenomic analysis has scarcely been used to investigate food systems. The present work reports a functional metagenomic analysis of the prevalence and evolution of tetracycline resistance determinants in a raw-milk, blue-veined cheese during manufacturing and ripening. For this, the same cheese batch was sampled and analyzed on days 3 and 60 of manufacture. Samples were diluted and grown in the presence of tetracycline on plate count milk agar (PCMA) (non-selective) and de Man Rogosa and Sharpe (MRS) agar (selective for lactic acid bacteria, LAB). DNA from the cultured bacteria was then isolated and used to construct four fosmid libraries, named after the medium and sampling time: PCMA-3D, PCMA-60D, MRS-3D, and MRS-60D. Clones in the libraries were subjected to restriction enzyme analysis, PCR amplification, and sequencing. Among the 300 fosmid clones analyzed, 268 different EcoRI restriction profiles were encountered. Sequence homology of their extremes clustered the clones into 47 groups. Representative clones of all groups were then screened for the presence of tetracycline resistance genes by PCR, targeting well-recognized genes coding for ribosomal protection proteins and efflux pumps. A single tetracycline resistance gene was detected in each of the clones, with four such resistance genes identified in total: tet(A), tet(L), tet(M), and tet(S). tet(A) was the only gene identified in the PCMA-3D library, and tet(L) the only one identified in the PCMA-60D and MRS-60D libraries. tet(M) and tet(S) were both detected in the MRS-3D library and in similar numbers. Six representative clones of the libraries were sequenced and analyzed. Long segments of all clones but one showed extensive homology to plasmids from Gram

  20. A Functional Metagenomic Analysis of Tetracycline Resistance in Cheese Bacteria.

    PubMed

    Flórez, Ana B; Vázquez, Lucía; Mayo, Baltasar

    2017-01-01

    Metagenomic techniques have been successfully used to monitor antibiotic resistance genes in environmental, animal and human ecosystems. However, despite the claim that the food chain plays a key role in the spread of antibiotic resistance, metagenomic analysis has scarcely been used to investigate food systems. The present work reports a functional metagenomic analysis of the prevalence and evolution of tetracycline resistance determinants in a raw-milk, blue-veined cheese during manufacturing and ripening. For this, the same cheese batch was sampled and analyzed on days 3 and 60 of manufacture. Samples were diluted and grown in the presence of tetracycline on plate count milk agar (PCMA) (non-selective) and de Man Rogosa and Sharpe (MRS) agar (selective for lactic acid bacteria, LAB). DNA from the cultured bacteria was then isolated and used to construct four fosmid libraries, named after the medium and sampling time: PCMA-3D, PCMA-60D, MRS-3D, and MRS-60D. Clones in the libraries were subjected to restriction enzyme analysis, PCR amplification, and sequencing. Among the 300 fosmid clones analyzed, 268 different EcoRI restriction profiles were encountered. Sequence homology of their extremes clustered the clones into 47 groups. Representative clones of all groups were then screened for the presence of tetracycline resistance genes by PCR, targeting well-recognized genes coding for ribosomal protection proteins and efflux pumps. A single tetracycline resistance gene was detected in each of the clones, with four such resistance genes identified in total: tet(A), tet(L), tet(M), and tet(S). tet(A) was the only gene identified in the PCMA-3D library, and tet(L) the only one identified in the PCMA-60D and MRS-60D libraries. tet(M) and tet(S) were both detected in the MRS-3D library and in similar numbers. Six representative clones of the libraries were sequenced and analyzed. Long segments of all clones but one showed extensive homology to plasmids from Gram

  1. Release of Antibiotic Resistant Bacteria by a Waste Treatment Plant from Romania.

    PubMed

    Lupan, Iulia; Carpa, Rahela; Oltean, Andreea; Kelemen, Beatrice Simona; Popescu, Octavian

    2017-09-27

    The occurrence and spread of bacterial antibiotic resistance are subjects of great interest, and the role of wastewater treatment plants has been attracting particular interest. These stations are a reservoir of bacteria, have a large range of organic and inorganic substances, and the amount of bacteria released into the environment is very high. The main purpose of the present study was to assess the removal degree of bacteria with resistance to antibiotics and identify the contribution of a wastewater treatment plant to the microbiota of Someşul Mic river water in Cluj county. The resistance to sulfamethoxazole and tetracycline and some of their representative resistance genes: sul1, tet(O), and tet(W) were assessed in this study. The results obtained showed that bacteria resistant to sulphonamides were more abundant than those resistant to tetracycline. The concentration of bacteria with antibiotic resistance changed after the treatment, namely, bacteria resistant to sulfamethoxazole. The removal of all bacteria and antibiotic-resistant bacteria was 98-99% and the degree of removal of bacteria resistant to tetracycline was higher than the bacteria resistant to sulfamethoxazole compared to total bacteria. The wastewater treatment plant not only contributed to elevating ARG concentrations, it also enhanced the possibility of horizontal gene transfer (HGT) by increasing the abundance of the intI1 gene. Even though the treatment process reduced the concentration of bacteria by two orders of magnitude, the wastewater treatment plant in Cluj-Napoca contributed to an increase in antibiotic-resistant bacteria concentrations up to 10 km downstream of its discharge in Someşul Mic river.

  2. The role of midgut symbiotic bacteria in resistance of Anopheles stephensi (Diptera: Culicidae) to organophosphate insecticides.

    PubMed

    Soltani, Aboozar; Vatandoost, Hassan; Oshaghi, Mohammad Ali; Enayati, Ahmad Ali; Chavshin, Ali Reza

    2017-07-26

    In the current study, the effects of the presence of symbiotic bacteria on the activity of the enzymes involved in An. stephensi resistance to temephos are evaluated for the first time. Four different strains (I. susceptible strain, II. resistant strain, III. resistant strain + antibiotic, and IV. resistant strain + bacteria) were considered in order to determine the possible effects of the symbiotic bacteria on their hosts' resistance to temephos. The median values of all enzymes of susceptible strain were compared with those of other resistant strains. The results of this study indicated a direct relationship between the presence of bacteria in the symbiotic organs of An. stephensi and resistance to temephos. The profile of enzymatic activities in the resistant strain changed to a susceptible status after adding antibiotic. The resistance of An. stephensi to temephos could be completely broken artificially by removing their bacterial symbionts in a resistant population.

  3. [Travels and spreading of multi-resistant bacteria].

    PubMed

    Nitsch-Osuch, Aneta

    2017-05-23

    The increasing number of international travel for tourism, business and for medical reasons rises the risk of spreading of multi-resistant bacteria. It has been shown that an intercontinental travel, mainly to Asia (Indian Subcontinent), promotes a colonization of the digestive tract, mainly by multi-resistant Enterobacteriaceae (MRE) and increases the risk of symptomatic infections caused by these agents. The colonization of the digestive tract by MRE is reported in 29-88% of travelers. It sustains 3 to 12 months, respectively in 10% and 2% of travelers. Risk factors for the acquisition of colonization with MRE include: travel duration and destination, treatment with betalactam antibiotics during the travel, the use of local medical services, including hospitalization, presence of gastrointestinal symptoms during the travel (mainly diarrhea), age >65 years. The need of the hospitalization during the travel increases the risk of colonization, but is not a prerequisite factor for the acquisition of the colonization, as cases of the MRE carriage are reported in patients who had never used medical services outside the country. It indicates other possible transmission routes, including food. In order to reduce the risk of MRE spreading, it is recommended to ask patients about a history of travel and treatment within the last 12 months. All patient who report such events and require hospitalization in their home countries should be microbiologically screened. Hospitalized patients colonized with multiple resistant bacteria require an isolation or cohortation. Educational activities related to the hand hygiene compliance should be performed. The risk of the home transmission of MRE is not high, it lasts for a short period (up to 3 months). Routine microbiological testing for all persons returning from an international or intercontinental travel is not recommended, neither microbiological screening among their households.

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

    PubMed Central

    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

  5. Symbiotic interactions between free-living amoeba and harboured mercury-resistant bacteria.

    PubMed

    Hagneré, C; Harf, C

    1993-05-28

    A co-culture of environmental Acanthamoeba sp. associated to Hg-sensitive, narrow or broad-spectrum Hg-resistant Aeromonas sp. strains was exposed to HgCl(2) and phenylmercuric acetate. Amoebic growth depended on the Hg-resistance determinants of harboured bacteria. This laboratory model helped in understanding the mechanisms of Hg-resistance observed in amoeba isolated in river waters after a mercuric pollution. Amoeba acquired Hg-resistance by using symbiotic resistant bacteria.

  6. Hexavalent chromium-resistant bacteria isolated from river sediments.

    PubMed Central

    Luli, G W; Talnagi, J W; Strohl, W R; Pfister, R M

    1983-01-01

    Hexavalent chromium [Cr(VI)] is a known carcinogen and mutagen; however, the actual mechanisms of Cr toxicity are unknown. Two approaches were used to isolate Cr(VI)-resistant bacteria from metal-contaminated river sediments. Diluted sediments were plated directly onto a peptone-yeast extract (PYE) medium containing 0 to 100 micrograms of Cr(VI) ml-1. Approximately 8.4 x 10(5) CFU g-1 were recovered on 0 microgram of Cr(VI) ml-1, whereas 4.0 x 10(2) CFU g-1 were recovered on PYE plus 100 micrograms of Cr(VI) ml-1. Alternatively, continuous culture enrichment techniques were employed using PYE and 100 micrograms Cr(VI) ml-1 input at dilution rates of 0.02 and 0.10 h-1. After six residence periods, 10(9) CFU were recovered on PYE agar containing 0 microgram of Cr(VI) ml-1 and 10(7) CFU on PYE agar plus 100 micrograms of Cr(VI) ml-1. Of 89 isolates obtained by direct plating onto PYE, 47% were resistant to 100 micrograms of Cr(VI) ml-1, and 29% were resistant to 250 micrograms of Cr(VI) ml-1. When the same isolates were plated onto PYE containing Cr(III), 88% were resistant to 100 micrograms ml-1 but only 2% were resistant to 250 micrograms ml-1. Cr, Co, Sb, and Zn were found in significantly higher concentrations at an industry-related contaminated site than at a site 11 km downstream. Total Cr in the sediments at the contaminated site averaged 586 micrograms (dry weight) g-1, and the downstream site averaged 71 micrograms (dry weight) g-1. The Cr recovered from acid-digested Ottawa River sediment samples was predominantly hexavalent. Five acid digestion procedures followed by atomic absorption spectroscopy were compared and found to be 30 to 70% efficient for recovery of Cr relative to neutron activation analysis. A population of aerobic, heterotrophic bacteria was recovered from sediments containing elevated levels of Cr.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6639032

  7. A review of the influence of treatment strategies on antibiotic resistant bacteria and antibiotic resistance genes.

    PubMed

    Sharma, Virender K; Johnson, Natalie; Cizmas, Leslie; McDonald, Thomas J; Kim, Hyunook

    2016-05-01

    Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) in the aquatic environment have become an emerging contaminant issue, which has implications for human and ecological health. This review begins with an introduction to the occurrence of ARB and ARG in different environmental systems such as natural environments and drinking water resources. For example, ARG or ARB with resistance to ciprofloxacin, sulfamethoxazole, trimethoprim, quinolone, vancomycin, or tetracycline (e.g., tet(A), tet(B), tet(C), tet(G), tet(O), tet(M), tet(W), sul I, and sul II) have been detected in the environment. The development of resistance may be intrinsic, may be acquired through spontaneous mutations (de novo), or may occur due to horizontal gene transfer from donor bacteria, phages, or free DNA to recipient bacteria. An overview is also provided of the current knowledge regarding inactivation of ARB and ARG, and the mechanism of the effects of different disinfection processes in water and wastewater (chlorination, UV irradiation, Fenton reaction, ozonation, and photocatalytic oxidation). The effects of constructed wetlands and nanotechnology on ARB and ARG are also summarized.

  8. Antibiotic-resistant bacteria in the Hudson River Estuary linked to wet weather sewage contamination.

    PubMed

    Young, Suzanne; Juhl, Andrew; O'Mullan, Gregory D

    2013-06-01

    Heterotrophic bacteria resistant to tetracycline and ampicillin were assessed in waterways of the New York City metropolitan area using culture-dependent approaches and 16S rRNA gene sequence analysis of resultant isolates. Resistant microbes were detected at all 10 sampling sites in monthly research cruises on the lower Hudson River Estuary (HRE), with highest concentrations detected at nearshore sites. Higher frequency sampling was conducted in Flushing Bay, to enumerate resistant microbes under both dry and wet weather conditions. Concentrations of ampicillin- and tetracycline-resistant bacteria, in paired samples, were positively correlated with one another and increased following precipitation. Counts of the fecal indicator, Enterococcus, were positively correlated with levels of resistant bacteria, suggesting a shared sewage-associated source. Analysis of 16S rRNA from isolates identified a phylogenetically diverse group of resistant bacteria, including genera containing opportunistic pathogens. The occurrence of Enterobacteriaceae, a family of enteric bacteria, was found to be significantly higher in resistant isolates compared to total heterotrophic bacteria and increased following precipitation. This study is the first to document the widespread distribution of antibiotic-resistant bacteria in the HRE and to demonstrate clearly a link between the abundance of antibiotic-resistant bacteria and levels of sewage-associated bacteria in an estuary.

  9. Relationship between antibiotic- and disinfectant-resistance profiles in bacteria harvested from tap water.

    PubMed

    Khan, Sadia; Beattie, Tara K; Knapp, Charles W

    2016-06-01

    Chlorination is commonly used to control levels of bacteria in drinking water; however, viable bacteria may remain due to chlorine resistance. What is concerning is that surviving bacteria, due to co-selection factors, may also have increased resistance to common antibiotics. This would pose a public health risk as it could link resistant bacteria in the natural environment to human population. Here, we investigated the relationship between chlorine- and antibiotic-resistances by harvesting 148 surviving bacteria from chlorinated drinking-water systems and compared their susceptibilities against chlorine disinfectants and antibiotics. Twenty-two genera were isolated, including members of Paenibacillus, Burkholderia, Escherichia, Sphingomonas and Dermacoccus species. Weak (but significant) correlations were found between chlorine-tolerance and minimum inhibitory concentrations against the antibiotics tetracycline, sulfamethoxazole and amoxicillin, but not against ciprofloxacin; this suggest that chlorine-tolerant bacteria are more likely to also be antibiotic resistant. Further, antibiotic-resistant bacteria survived longer than antibiotic-sensitive organisms when exposed to free chlorine in a contact-time assay; however, there were little differences in susceptibility when exposed to monochloramine. Irrespective of antibiotic-resistance, spore-forming bacteria had higher tolerance against disinfection compounds. The presence of chlorine-resistant bacteria surviving in drinking-water systems may carry additional risk of antibiotic resistance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Bacteriophages as potential treatment option for antibiotic resistant bacteria.

    PubMed

    Bragg, Robert; van der Westhuizen, Wouter; Lee, Ji-Yun; Coetsee, Elke; Boucher, Charlotte

    2014-01-01

    The world is facing an ever-increasing problem with antibiotic resistant bacteria and we are rapidly heading for a post-antibiotic era. There is an urgent need to investigate alterative treatment options while there are still a few antibiotics left. Bacteriophages are viruses that specifically target bacteria. Before the development of antibiotics, some efforts were made to use bacteriophages as a treatment option, but most of this research stopped soon after the discovery of antibiotics. There are two different replication options which bacteriophages employ. These are the lytic and lysogenic life cycles. Both these life cycles have potential as treatment options. There are various advantages and disadvantages to the use of bacteriophages as treatment options. The main advantage is the specificity of bacteriophages and treatments can be designed to specifically target pathogenic bacteria while not negatively affecting the normal microbiota. There are various advantages to this. However, the high level of specificity also creates potential problems, the main being the requirement of highly specific diagnostic procedures. Another potential problem with phage therapy includes the development of immunity and limitations with the registration of phage therapy options. The latter is driving research toward the expression of phage genes which break the bacterial cell wall, which could then be used as a treatment option. Various aspects of phage therapy have been investigated in studies undertaken by our research group. We have investigated specificity of phages to various avian pathogenic E. coli isolates. Furthermore, the exciting NanoSAM technology has been employed to investigate bacteriophage replication and aspects of this will be discussed.

  11. Mortality in Patients With Septic Shock by Multidrug Resistant Bacteria.

    PubMed

    Busani, Stefano; Serafini, Giulia; Mantovani, Elena; Venturelli, Claudia; Giannella, Maddalena; Viale, Pierluigi; Mussini, Cristina; Cossarizza, Andrea; Girardis, Massimo

    2017-01-01

    Patients with septic shock by multidrug resistant (MDR) microorganism maybe considered a specific population of critical patients at very high risk of death in whom the effects of standard sepsis treatment has never been assessed. The objective of this retrospective analysis was to evaluate the risk factors for 30-day mortality and the impact of sepsis management in patients with septic shock caused by MDR bacteria. Patients with septic shock by MDR bacteria admitted to the mixed intensive care unit (ICU) of Modena University Hospital during a 6-year period were studied. The clinical and microbiological characteristics and sepsis treatments provided were analyzed and compared between survivors (S) and nonsurvivors (NS) at 30 days after septic shock appearance. Ninety-four patients were studied. All therapeutic interventions applied to patients during their ICU stay did not show statistical significance between S and NS groups, except for administration of immunoglobulin M (IgM) preparation which were provided more frequently in S group ( P < .05). At the multivariate adjusted analysis, preexisting cancer (odds ratio [OR] = 2.965) and Acinetobacter baumannii infections (OR = 3.197) were independently correlated with an increased risk of 30-day mortality, whereas treatment with IgM preparation was protective (OR = 0.283). This retrospective study showed that in patients with septic shock caused by MDR bacteria, history of cancer and infection sustained by A baumannii increase the risk of mortality and that standard sepsis treatments do not seem to provide any protective effect. Adjunctive therapy with IgM preparation seems to be beneficial, but further appropriate studies are needed to confirm the results observed.

  12. Computational modeling of drug-resistant bacteria. Final report

    SciTech Connect

    MacDougall, Preston

    2015-03-12

    Initial proposal summary: The evolution of antibiotic-resistant mutants among bacteria (superbugs) is a persistent and growing threat to public health. In many ways, we are engaged in a war with these microorganisms, where the corresponding arms race involves chemical weapons and biological targets. Just as advances in microelectronics, imaging technology and feature recognition software have turned conventional munitions into smart bombs, the long-term objectives of this proposal are to develop highly effective antibiotics using next-generation biomolecular modeling capabilities in tandem with novel subatomic feature detection software. Using model compounds and targets, our design methodology will be validated with correspondingly ultra-high resolution structure-determination methods at premier DOE facilities (single-crystal X-ray diffraction at Argonne National Laboratory, and neutron diffraction at Oak Ridge National Laboratory). The objectives and accomplishments are summarized.

  13. Suppression of resistance to flow in suspensions of bacteria

    NASA Astrophysics Data System (ADS)

    Lopez, Hector; Gachelin, Jérémie; Douarche, Carine; Clément, Eric; Auradou, Harold

    2014-11-01

    It is usually believed that the influence of small amounts of bacteria on the rheological properties of a fluid is negligible. However, recent theoretical studies predict that the activity results in a decrease of the viscosity at values lower than the suspending fluid viscosity. We present experimental measurements of the viscosity of suspensions of Escherichia coli (volume fractions ϕ<1%) in a simple Couette flow over a broad range of shear rates. For shear rates larger than 1.5 s-1, the viscosity is constant and slightly above the viscosity of the suspending fluid. This behavior is similar to the one expected for non-active particles. For lower shear rates the fluid exhibits a non-Newtonian behavior: the viscosity decreases and finally reaches a second Newtonian plateau for shear rates below 0.1 s-1. For ϕ <0.6%, the decrease is proportional to the bacteria concentration, as predicted by the theories, suggesting that it is a result of the energy input of each individual microswimmer. For ϕ >0.6%, we evidence for the first time the existence of a super-lubrication regime where the viscous resistance to shear vanishes. We will demonstrate that this regime holds up over a large window of concentration.

  14. [Inactivation and reactivation of antibiotic-resistant bacteria during and after UV disinfection in reclaimed water].

    PubMed

    Huang, Jing-Jing; Tang, Fang; Xi, Jin-Ying; Pang, Yu-Chen; Hu, Hong-Ying

    2014-04-01

    Prevalence of antibiotic-resistant bacteria in wastewater effluents is concerned as an emerging contaminant. To estimate inactivation and reactivation potentials of antibiotic-resistant bacteria by UV disinfection, inactivation and reactivation of penicillin-, ampicillin-, cephalexin-, chloramphenicol-and rifampicin-resistant bacteria in the secondary effluent were studied under different UV doses. The results showed that the inactivation ratios of penicillin-, ampicillin-, cephalexin-and chloramphenicol-resistant bacteria were higher than 4-log, which was closed to that of total heterotrophic bacteria; however, the inactivation ratio of rifampicin-resistant bacteria was lower (3.7-log) under 20 mJ x cm(-2) UV exposure. After 22 h standing incubation, antibiotic-resistant bacteria widely reactivated. The colony forming ability of antibiotic-resistant bacteria was as high as 3-log when exposed to 20 mJ x cm(-2) UV light. Hence, conventional UV dose can not effectively control reactivation of antibiotic-resistant bacteria in reclaimed water by UV disinfection.

  15. Interplay Between Antibiotic Resistance and Virulence During Disease Promoted by Multidrug-Resistant Bacteria.

    PubMed

    Geisinger, Edward; Isberg, Ralph R

    2017-02-15

    Diseases caused by antibiotic-resistant bacteria in hospitals are the outcome of complex relationships between several dynamic factors, including bacterial pathogenicity, the fitness costs of resistance in the human host, and selective forces resulting from interventions such as antibiotic therapy. The emergence and fate of mutations that drive antibiotic resistance are governed by these interactions. In this review, we will examine how different forms of antibiotic resistance modulate bacterial fitness and virulence potential, thus influencing the ability of pathogens to evolve in the context of nosocomial infections. We will focus on 3 important multidrug-resistant pathogens that are notoriously problematic in hospitals: Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus. An understanding of how antibiotic resistance mutations shape the pathobiology of multidrug-resistant infections has the potential to drive novel strategies that can control the development and spread of drug resistance. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, email: journals.permissions@oup.com.

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

    PubMed Central

    Yosef, Ido; Manor, Miriam; Kiro, Ruth

    2015-01-01

    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. PMID:26060300

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

    PubMed

    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.

  18. Microbial selectivity of UV treatment on antibiotic-resistant heterotrophic bacteria in secondary effluents of a municipal wastewater treatment plant.

    PubMed

    Guo, Mei-Ting; Yuan, Qing-Bin; Yang, Jian

    2013-10-15

    Little is known about the microbial selectivity of UV treatment for antibiotic resistant bacteria, and the results of limited studies are conflicting. To understand the effect of UV disinfection on antibiotic resistant bacteria, both total heterotrophic bacteria and antibiotic resistant bacteria (including cephalexin-, ciprofloxacin-, erythromycin-, gentamicin-, vancomycin-, sulfadiazine-, rifampicin-, tetracycline- and chloramphenicol-resistant bacteria) were examined in secondary effluent samples from a municipal wastewater treatment plant. Bacteria resistant to both erythromycin and tetracycline were chosen as the representative of multiple-antibiotic-resistant bacteria and their characteristics after UV treatment were also investigated. UV disinfection results in effective inactivation for total heterotrophic bacteria, as well as all antibiotic resistant bacteria. After UV treatment at a fluence of 5 mJ/cm(2), the log reductions of nine types of antibiotic resistant bacteria varied from 1.0 ± 0.1 to 2.4 ± 0.1. Bacteria resistant to both erythromycin and tetracycline had a similar fluence response as did total heterotrophic bacteria. The findings suggest that UV disinfection could eliminate antibiotic resistance in wastewater treatment effluents and thus ensure public health security. Our experimental results indicated that UV disinfection led to enrichment of bacteria with resistance to sulfadiazine, vancomycin, rifampicin, tetracycline and chloramphenicol, while the proportions of cephalexin-, erythromycin-, gentamicin- and ciprofloxacin-resistant bacteria in the wastewater decreased. This reveals the microbial selectivity of UV disinfection for antibiotic resistant bacteria. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Molecular characterizations of chloramphenicol- and oxytetracycline-resistant bacteria and resistance genes in mariculture waters of China.

    PubMed

    Dang, Hongyue; Zhao, Jingyi; Song, Linsheng; Chen, Mingna; Chang, Yaqing

    2009-07-01

    In order to gain an understanding of the diversity and distribution of antimicrobial-resistant bacteria and their resistance genes in maricultural environments, multidrug-resistant bacteria were screened for the rearing waters from a mariculture farm of China. Both abalone Haliotis discushannai and turbot Scophthalmus maximus rearing waters were populated with abundant chloramphenicol-resistant bacteria. These bacteria were also multidrug resistant, with Vibriosplendidus and Vibriotasmaniensis being the most predominant species. The chloramphenicol-resistance gene cat II, cat IV or floR could be detected in most of the multidrug-resistant isolates, and the oxytetracycline-resistance gene tet(B), tet(D), tet(E) or tet(M) could also be detected for most of the isolates. Coexistence of chloramphenicol- and oxytetracycline-resistance genes partially explains the molecular mechanism of multidrug resistance in the studied maricultural environments. Comparative studies with different antimicrobial agents as the starting isolation reagents may help detect a wider diversity of the antimicrobial-resistant bacteria and their resistance genes.

  20. Distribution and characterization of kepone-resistant bacteria in the aquatic environment.

    PubMed

    Orndorff, S A; Colwell, R R

    1980-03-01

    Effects of the chlorinated insecticide Kepone on the ecology of Chesapeake Bay and James River bacteria were studied. Kepone-resistant bacteria present in a given environment were found to reflect the degree of fecal and/or high organic pollution of the sampling sites, based on total numbers and generic composition of the populations of Kepone-resistant bacteria. The presence of Kepone-resistant bacteria was found to be correlated (alpha = 0.01) with total coliforms, fecal coliforms, and total aerobic viable heterotrophic bacteria, but not with Kepone concentration, since Kepone-resistant bacteria were present in locations where Kepone could not be detected by the analytical methods used in this study. Only gram-negative bacteria, predominantly Pseudomonas, Vibrio, and Aeromonas spp., were found to be resistant to >/=10 mug of Kepone per ml. Gram-positive bacteria, i.e., Bacillus and Corynebacterium spp., were generally sensitive to >/=0.1 mug of Kepone per ml. From results of cluster analysis of taxonomic data, we determined that characteristics of Kepone-resistant bacteria included: resistance to pesticides and heavy metals; degradation of oil; positive oxidase and catalase reactions; and nitrate reduction. From results of the ecological and taxonomic analyses, we conclude that Kepone resistance in estuarine bacteria is due to the physicochemical composition of the gram-negative cell wall and not prior exposure to Kepone. Therefore, the presence of Kepone-resistant bacteria cannot serve as an indicator of Kepone contamination in the aquatic environment where gram-negative bacteria are predominant.

  1. Molecular characterizations of oxytetracycline resistant bacteria and their resistance genes from mariculture waters of China.

    PubMed

    Dang, Hongyue; Zhang, Xiaoxia; Song, Linsheng; Chang, Yaqing; Yang, Guanpin

    2006-11-01

    Oxytetracycline-resistant bacteria were isolated from a mariculture farm in China, and accounted for 32.23% and 5.63% of the total culturable microbes of the sea cucumber and the sea urchin rearing waters respectively. Marine vibrios, especially strains related to Vibrio splendidus or V. tasmaniensis, were the most abundant resistant isolates. For oxytetracycline resistance, tet(A), tet(B) and tet(D) genes were detected in both sea cucumber and sea urchin rearing ponds. The dominant resistance type for V. tasmaniensis-like strains was the combination of both tet(A) and tet(B) genes, while the major resistance type for V. splendidus-like strains was a single tet(D) gene. Most of the sea cucumber tet-positive isolates harbored a chloramphenicol-resistance gene, either cat IV or cat II, while only a few sea urchin tet-positive isolates harbored a cat gene, actually cat IV. The coexistence of tet and cat genes in the strains isolated from the mariculture farm studied was helpful in explaining some of the multi-resistance mechanisms.

  2. Determinants encoding resistance to several heavy metals in newly isolated copper-resistant bacteria

    SciTech Connect

    Dressler, C.; Kues, U.; Nies, D.H.; Friedrich, B. )

    1991-11-01

    Three copper-resistant, gram-negative bacteria were isolated and characterized. Of the three strains, Alcaligenes dentrificans AH tolerated the highest copper concentration (MIC = 4 mM CuSO{sub 4}). All three strains showed various levels of resistance to other metal ions. A. denitrificans AH contains sequences which cross-hybridized with the mer (mercury resistance) determinant of Tn21 and the czc (cobalt, zinc, and cadmium resistance), cnr (cobalt and nickel resistance), and chr (chromate resistance) determinants of A. eutrophus CH34. DNA-DNA hybridization with probes prepared from A. eutrophus CH34 and Tn21 revealed the presence of chr-, cnr-, and mer-like sequences on the 200-kb plasmid pHG27 and of czc, cnr, and mer homologs located on the chromosomes. The second strain, classified as Alcaligenes sp. strain PW, carries czc, cnr, and mer homologs on the 240-kb plasmid pHG29-c and chr determinant on the 290-kb plasmid pHG29-a; a third plasmid, the 260-kb large plasmid pHG29-b, is cryptic. In contrast to the Alcaligenes strains, which were isolated from metal-contaminated water, Pseudomonas paucimobilis CD was isolated from the air. This strain harbors two cryptic plasmids: the 210-kb large plasmid pHG28-a and the 40-kb plasmid pHG28-b. Southern analysis revealed no homology between the metal ion resistance determinants of A. eutrophus CH34 and P. paucimonilis CD.

  3. [From the discovery of antibiotics to emerging highly drug-resistant bacteria].

    PubMed

    Meunier, Olivier

    2015-01-01

    The discovery of antibiotics has enabled serious infections to be treated. However, bacteria resistant to several families of antibiotics and the emergence of new highly drug-resistant bacteria constitute a public health issue in France and across the world. Actions to prevent their transmission are being put in place. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  4. Chlortetracycline-Resistant Intestinal Bacteria in Organically Raised and Feral Swine ▿

    PubMed Central

    Stanton, Thad B.; Humphrey, Samuel B.; Stoffregen, William C.

    2011-01-01

    Organically raised swine had high fecal populations of chlortetracycline (CTC)-resistant (growing at 64 μg CTC/ml) Escherichia coli, Megasphaera elsdenii, and anaerobic bacteria. By comparison, CTC-resistant bacteria in feral swine feces were over 1,000-fold fewer and exhibited lower taxonomic diversity. PMID:21821750

  5. Irrigation waters and pipe-based biofilms as sources for antibiotic-resistant bacteria

    USDA-ARS?s Scientific Manuscript database

    The presence of antibiotic-resistant bacteria in environmental surface waters has gained recent attention. Wastewater- and drinking water distribution systems are known to disseminate antibiotic-resistant bacteria, with the biofilms that form on the inner-surfaces of the pipeline as a hotspot for pr...

  6. [The role of hospital teams in the management of patients carrying highly drug-resistant bacteria].

    PubMed

    Clément, Agnès; Denis, Christine

    2015-01-01

    The increase in antibiotic-resistant bacteria and emerging highly drug-resistant bacteria is resulting in alarming situations of treatment failure. In hospitals, precautionary measures to control nosocomial infections are put in place through the collaboration between caregivers, the operational hygiene team and the nosocomial infection control committee, in accordance with official recommendations.

  7. [Mercury-resistant bacteria from permafrost sediments and prospects for their use in comparative studies of mercury resistance determinants].

    PubMed

    Petrova, M A; Mindlin, S Z; Gorlenko, Zh M; Kaliaeva, E S; Soina, V S; Bogdanova, E S

    2002-11-01

    Mercury-resistant bacteria were isolated from permafrost sediments of Kolyma lowland and Canada existing over five thousand to two million years. Their content was shown to vary within the range 0.001-2.9% and to depend on the amount of mercury in sampling sites (coefficient of correlation 0.75). A collection of mercury-resistant bacterial strains was created. In this collection, various representatives of both Gram-positive bacteria (Bacillus, Exiguobacterium, Micrococcus, Arthrobacter) and Gram-negative bacteria (Pseudomonas, Acinetobacter, Plesiomonas, Myxobacteriales) were identified. Most resistant bacteria were found to contain determinants homologous to mer-operons of contemporary bacteria. The isolated strains of paleobacteria are proposed to be used for a comparative structural study of contemporary and ancient plasmids and transposons carrying mercury resistance determinants.

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

    PubMed Central

    Yang, Qingxiang; Zhang, Hao; Guo, Yuhui; Tian, Tiantian

    2016-01-01

    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. PMID:27376311

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

    PubMed

    Yang, Qingxiang; Zhang, Hao; Guo, Yuhui; Tian, Tiantian

    2016-06-30

    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.

  10. Bloodstream infections in intensive care unit patients: distribution and antibiotic resistance of bacteria

    PubMed Central

    Russotto, Vincenzo; Cortegiani, Andrea; Graziano, Giorgio; Saporito, Laura; Raineri, Santi Maurizio; Mammina, Caterina; Giarratano, Antonino

    2015-01-01

    Bloodstream infections (BSIs) are among the leading infections in critically ill patients. The case-fatality rate associated with BSIs in patients admitted to intensive care units (ICUs) reaches 35%–50%. The emergence and diffusion of bacteria with resistance to antibiotics is a global health problem. Multidrug-resistant bacteria were detected in 50.7% of patients with BSIs in a recently published international observational study, with methicillin resistance detected in 48% of Staphylococcus aureus strains, carbapenem resistance detected in 69% of Acinetobacter spp., in 38% of Klebsiella pneumoniae, and in 37% of Pseudomonas spp. Prior hospitalization and antibiotic exposure have been identified as risk factors for infections caused by resistant bacteria in different studies. Patients with BSIs caused by resistant strains showed an increased risk of mortality, which may be explained by a higher incidence of inappropriate empirical therapy in different studies. The molecular genetic characterization of resistant bacteria allows the understanding of the most common mechanisms underlying their resistance and the adoption of surveillance measures. Knowledge of epidemiology, risk factors, mechanisms of resistance, and outcomes of BSIs caused by resistant bacteria may have a major influence on global management of ICU patients. The aim of this review is to provide the clinician an update on BSIs caused by resistant bacteria in ICU patients. PMID:26300651

  11. Occurrence of airborne vancomycin- and gentamicin-resistant bacteria in various hospital wards in Isfahan, Iran

    PubMed Central

    Mirhoseini, Seyed Hamed; Nikaeen, Mahnaz; Khanahmad, Hossein; Hassanzadeh, Akbar

    2016-01-01

    Background: Airborne transmission of pathogenic resistant bacteria is well recognized as an important route for the acquisition of a wide range of nosocomial infections in hospitals. The aim of this study was to determine the prevalence of airborne vancomycin and gentamicin (VM and GM) resistant bacteria in different wards of four educational hospitals. Materials and Methods: A total of 64 air samples were collected from operating theater (OT), Intensive Care Unit (ICU), surgery ward, and internal medicine ward of four educational hospitals in Isfahan, Iran. Airborne culturable bacteria were collected using all glass impingers. Samples were analyzed for the detection of VM- and GM-resistant bacteria. Results: The average level of bacteria ranged from 99 to 1079 CFU/m3. The highest level of airborne bacteria was observed in hospital 4 (628 CFU/m3) and the highest average concentration of GM- and VM-resistant airborne bacteria were found in hospital 3 (22 CFU/m3). The mean concentration of airborne bacteria was the lowest in OT wards and GM- and VM-resistant airborne bacteria were not detected in this ward of hospitals. The highest prevalence of antibiotic-resistant airborne bacteria was observed in ICU ward. There was a statistically significant difference for the prevalence of VM-resistant bacteria between hospital wards (P = 0.012). Conclusion: Our finding showed that the relatively high prevalence of VM- and GM-resistant airborne bacteria in ICUs could be a great concern from the point of view of patients' health. These results confirm the necessity of application of effective control measures which significantly decrease the exposure of high-risk patients to potentially airborne nosocomial infections. PMID:27656612

  12. Amoeba-resisting bacteria found in multilamellar bodies secreted by Dictyostelium discoideum: social amoebae can also package bacteria.

    PubMed

    Paquet, Valérie E; Charette, Steve J

    2016-03-01

    Many bacteria can resist phagocytic digestion by various protozoa. Some of these bacteria (all human pathogens) are known to be packaged in multilamellar bodies produced in the phagocytic pathway of the protozoa and that are secreted into the extracellular milieu. Packaged bacteria are protected from harsh conditions, and the packaging process is suspected to promote bacterial persistence in the environment. To date, only a limited number of protozoa, belonging to free-living amoebae and ciliates, have been shown to perform bacteria packaging. It is still unknown if social amoebae can do bacteria packaging. The link between the capacity of 136 bacterial isolates to resist the grazing of the social amoeba Dictyostelium discoideum and to be packaged by this amoeba was investigated in the present study. The 45 bacterial isolates displaying a resisting phenotype were tested for their capacity to be packaged. A total of seven isolates from Cupriavidus, Micrococcus, Microbacterium and Rathayibacter genera seemed to be packaged and secreted by D. discoideum based on immunofluorescence results. Electron microscopy confirmed that the Cupriavidus and Rathayibacter isolates were formally packaged. These results show that social amoebae can package some bacteria from the environment revealing a new aspect of microbial ecology.

  13. Evolution of β-lactams resistance in Gram-negative bacteria in Tunisia.

    PubMed

    Chouchani, Chedly; Marrakchi, Rim; El Salabi, Allaaeddin

    2011-08-01

    Antimicrobial resistance is a major health problem worldwide, but marked variations in the resistance profiles of bacterial pathogens are found between countries and in different patient settings. In Tunisia, the strikingly high prevalence of resistance of bacteria to penicillins and cephalorosporins drugs including fourth generation in clinical isolates of Gram negative bacteria has been reported. During 30 years, the emerging problem of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae isolates is substantial, and some unique enzymes have been found. Recently, evidence that Gram-negative bacteria are resistant to nearly all available antimicrobial agents, including carbapenems, have emerged.

  14. Low Prevalence of Carbapenem-Resistant Bacteria in River Water: Resistance Is Mostly Related to Intrinsic Mechanisms.

    PubMed

    Tacão, Marta; Correia, António; Henriques, Isabel S

    2015-10-01

    Carbapenems are last-resort antibiotics to handle serious infections caused by multiresistant bacteria. The incidence of resistance to these antibiotics has been increasing and new resistance mechanisms have emerged. The dissemination of carbapenem resistance in the environment has been overlooked. The main goal of this research was to assess the prevalence and diversity of carbapenem-resistant bacteria in riverine ecosystems. The presence of frequently reported carbapenemase-encoding genes was inspected. The proportion of imipenem-resistant bacteria was on average 2.24 CFU/ml. Imipenem-resistant strains (n=110) were identified as Pseudomonas spp., Stenotrophomonas maltophilia, Aeromonas spp., Chromobacterium haemolyticum, Shewanella xiamenensis, and members of Enterobacteriaceae. Carbapenem-resistant bacteria were highly resistant to other beta-lactams such as quinolones, aminoglycosides, chloramphenicol, tetracyclines, and sulfamethoxazole/trimethoprim. Carbapenem resistance was mostly associated with intrinsically resistant bacteria. As intrinsic resistance mechanisms, we have identified the blaCphA gene in 77.3% of Aeromonas spp., blaL1 in all S. maltophilia, and blaOXA-48-like in all S. xiamenensis. As acquired resistance mechanisms, we have detected the blaVIM-2 gene in six Pseudomonas spp. (5.45%). Integrons with gene cassettes encoding resistance to aminoglycosides (aacA and aacC genes), trimethoprim (dfrB1b), and carbapenems (blaVIM-2) were found in Pseudomonas spp. Results suggest that carbapenem resistance dissemination in riverine ecosystems is still at an early stage. Nevertheless, monitoring these aquatic compartments for the presence of resistance genes and its host organisms is essential to outline strategies to minimize resistance dissemination.

  15. Possible impact of treated wastewater discharge on incidence of antibiotic resistant bacteria in river water.

    PubMed

    Iwane, T; Urase, T; Yamamoto, K

    2001-01-01

    Escherichia coli and coliform group bacteria resistant to seven antibiotics were investigated in the Tama River, a typical urbanized river in Tokyo, Japan, and at a wastewater treatment plant located on the river. The percentages of antibiotic resistance in the wastewater effluent were, in most cases, higher than the percentages in the river water, which were observed increasing downstream. Since the possible increase in the percentages in the river was associated with treated wastewater discharges, it was concluded that the river, which is contaminated by treated wastewater with many kinds of pollutants, is also contaminated with antibiotic resistant coliform group bacteria and E. coli. The percentages of resistant bacteria in the wastewater treatment plant were mostly observed decreasing during the treatment process. It was also demonstrated that the percentages of resistance in raw sewage are significantly higher than those in the river water and that the wastewater treatment process investigated in this study works against most of resistant bacteria in sewage.

  16. Resistance to β-lactams in Bacteria Isolated from Different Types of Portuguese Cheese

    PubMed Central

    Amador, Paula; Fernandes, Ruben; Prudêncio, Cristina; Brito, Luísa

    2009-01-01

    The purpose of this study was to investigate the presence of β-lactam-resistant bacteria in six different types of Portuguese cheese. The numbers of ampicillin resistant (AMPr) bacteria varied from 4.7 × 102 to 1.5 × 107 CFU/g. Within 172 randomly selected β-lactam-resistant bacteria, 44 resistant phenotypes were found and 31.4% were multidrug resistant. The majority (85%) of the isolates identified belonged to the Enterobacteriaceae family. The presence of the blaTEM gene was detected in 80.9% of the tested isolates. The results suggest that without thermal processing of the milk and good hygienic practices, cheese may act as a vehicle of transfer of β-lactam-resistant bacteria to the gastrointestinal tract of consumers. PMID:19468324

  17. Isolation and characterization of arsenic resistant bacteria from wastewater

    PubMed Central

    Abbas, Syed Zaghum; Riaz, Mehwish; Ramzan, Naseem; Zahid, M. Tariq; Shakoori, Farah R.; Rafatullah, Mohd.

    2014-01-01

    The present study proposed the isolation of arsenic resistant bacteria from wastewater. Only three bacterial isolates (MNZ1, MNZ4 and MNZ6) were able to grow in high concentrations of arsenic. The minimum inhibitory concentrations of arsenic against MNZ1, MNZ4 and MNZ6 were 300 mg/L, 300 mg/L and 370 mg/L respectively. The isolated strains showed maximum growth at 37 °C and at 7.0 pH in control but in arsenite stress Luria Bertani broth the bacterial growth is lower than control. All strains were arsenite oxidizing. All strains were biochemically characterized and ribotyping (16S rRNA) was done for the purpose of identification which confirmed that MNZ1 was homologous to Enterobacter sp. while MNZ4 and MNZ6 showed their maximum homology with Klebsiella pneumoniae. The protein profiling of these strains showed in arsenic stressed and non stressed conditions, so no bands of induced proteins appeared in stressed conditions. The bacterial isolates can be exploited for bioremediation of arsenic containing wastes, since they seem to have the potential to oxidize the arsenite (more toxic) into arsenate (less toxic) form. PMID:25763035

  18. Copper-resistant bacteria enhance plant growth and copper phytoextraction.

    PubMed

    Yang, Renxiu; Luo, Chunling; Chen, Yahua; Wang, Guiping; Xu, Yue; Shen, Zhenguo

    2013-01-01

    In this study, we investigated the role of rhizospheric bacteria in solubilizing soil copper (Cu) and promoting plant growth. The Cu-resistant bacterium DGS6 was isolated from a natural Cu-contaminated soil and was identified as Pseudomonas sp. DGS6. This isolate solubilized Cu in Cu-contaminated soil and stimulated root elongation of maize and sunflower. Maize was more sensitive to inoculation with DGS6 than was sunflower and exhibited greater root elongation. In pot experiment, inoculation with DGS6 increased the shoot dry weight of maize by 49% and sunflower by 34%, and increased the root dry weight of maize by 85% and sunflower by 45%. Although the concentrations of Cu in inoculated and non-inoculated seedlings did not differ significantly, the total accumulation of Cu in the plants increased after inoculation. DGS6 showed a high ability to solubilize P and produce iron-chelating siderophores, as well as significantly improved the accumulation of P and Fe in both maize and sunflower shoots. In addition, DGS6 produced indole-3-acetic acid (IAA) and ACC deaminase, which suggests that it may modulate ethylene levels in plants. The bacterial strain DGS6 could be a good candidate for re-vegetation of Cu-contaminated sites. Supplemental materials are available for this article. Go to the publisher's online edition of International Journal of Phytoremediation to view the supplemental file.

  19. The role of conjugative transposons in spreading antibiotic resistance between bacteria that inhabit the gastrointestinal tract.

    PubMed

    Scott, K P

    2002-12-01

    There is huge potential for genetic exchange to occur within the dense, diverse anaerobic microbial population inhabiting the gastrointestinal tract (GIT) of humans and animals. However, the incidence of conjugative transposons (CTns) and the antibiotic resistance genes they carry has not been well studied among this population. Since any incoming bacteria, including pathogens, can access this reservoir of genes, this oversight would appear to be an important one. Recent evidence has shown that anaerobic bacteria native to the rumen or hindgut harbour both novel antibiotic resistance genes and novel conjugative transposons. These CTns, and previously characterized CTns, can be transferred to a wide range of commensal bacteria under laboratory and in vivo conditions. The main evidence that gene transfer occurs widely in vivo between GIT bacteria, and between GIT bacteria and pathogenic bacteria, is that identical resistance genes are present in diverse bacterial species from different hosts.

  20. Molecular characterization of antibiotic resistance in cultivable multidrug-resistant bacteria from livestock manure.

    PubMed

    Yang, Qingxiang; Tian, Tiantian; Niu, Tianqi; Wang, Panliang

    2017-10-01

    Diverse antibiotic-resistance genes (ARGs) are frequently reported to have high prevalence in veterinary manure samples due to extensive use of antibiotics in farm animals. However, the characteristics of the distribution and transmission of ARGs among bacteria, especially among different species of multiple antibiotic-resistant bacteria (MARB), have not been well explored. By applying high-throughput sequencing methods, our study uncovered a vast MARB reservoir in livestock manure. The genera Escherichia, Myroides, Acinetobacter, Proteus, Ignatzschineria, Alcaligenes, Providencia and Enterococcus were the predominant cultivable MARB, with compositions of 40.6%-85.7%. From chicken manure isolates, 33 MARB were selected for investigation of the molecular characteristics of antibiotic resistance. A total of 61 ARGs and 18 mobile genetic elements (MGEs) were investigated. We found that 47 ARGs were widely distributed among the 33 MARB isolates. Each isolate carried 27-36 genes responsible for resistance to eight classes of antibiotics frequently used in clinic or veterinary settings. ARGs to the six classes of antibiotics other than streptogramins and vancomycin were present in all 33 MARB isolates with a prevalence of 80%-100%. A total of 12 MGEs were widely distributed among the 33 MARB, with intI1, IS26, ISaba1, and ISEcp1 simultaneously present in 100% of isolates. In addition, 9 gene cassettes within integrons and ISCR1 were detected among MARB isolates encoding resistance to different antibiotic classes. This is the first report revealing the general co-presence of multiple ARGs, various MGEs and ARG cassettes in different species of individual MARB isolates in chicken manure. The results highlight a much higher risk of ARGs spreading through livestock manure to humans than we expected. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Density-dependent adaptive resistance allows swimming bacteria to colonize an antibiotic gradient.

    PubMed

    Hol, Felix J H; Hubert, Bert; Dekker, Cees; Keymer, Juan E

    2016-01-01

    During antibiotic treatment, antibiotic concentration gradients develop. Little is know regarding the effects of antibiotic gradients on populations of nonresistant bacteria. Using a microfluidic device, we show that high-density motile Escherichia coli populations composed of nonresistant bacteria can, unexpectedly, colonize environments where a lethal concentration of the antibiotic kanamycin is present. Colonizing bacteria establish an adaptively resistant population, which remains viable for over 24 h while exposed to the antibiotic. Quantitative analysis of multiple colonization events shows that collectively swimming bacteria need to exceed a critical population density in order to successfully colonize the antibiotic landscape. After colonization, bacteria are not dormant but show both growth and swimming motility under antibiotic stress. Our results highlight the importance of motility and population density in facilitating adaptive resistance, and indicate that adaptive resistance may be a first step to the emergence of genetically encoded resistance in landscapes of antibiotic gradients.

  2. Density-dependent adaptive resistance allows swimming bacteria to colonize an antibiotic gradient

    PubMed Central

    Hol, Felix J H; Hubert, Bert; Dekker, Cees; Keymer, Juan E

    2016-01-01

    During antibiotic treatment, antibiotic concentration gradients develop. Little is know regarding the effects of antibiotic gradients on populations of nonresistant bacteria. Using a microfluidic device, we show that high-density motile Escherichia coli populations composed of nonresistant bacteria can, unexpectedly, colonize environments where a lethal concentration of the antibiotic kanamycin is present. Colonizing bacteria establish an adaptively resistant population, which remains viable for over 24 h while exposed to the antibiotic. Quantitative analysis of multiple colonization events shows that collectively swimming bacteria need to exceed a critical population density in order to successfully colonize the antibiotic landscape. After colonization, bacteria are not dormant but show both growth and swimming motility under antibiotic stress. Our results highlight the importance of motility and population density in facilitating adaptive resistance, and indicate that adaptive resistance may be a first step to the emergence of genetically encoded resistance in landscapes of antibiotic gradients. PMID:26140531

  3. Detection and Characterizations of Genes Resistant to Tetracycline and Sulfa among the Bacteria in Mariculture Water

    NASA Astrophysics Data System (ADS)

    Qu, L.; Li, Y.; Zhu, P.

    2013-12-01

    One hundred and thirty-five bacteria from maricultural environments were tested for sensitivity to tetracycline and sulfa. Result show that 72% of the bacteria were sulfa-resistant, 36% of the bacteria were tetracycline-resistant, and 16.5% of bacteria showed resistance to both tetracyclines and sulfa ,indicating that the proportion of sulfa and tetracycline resistance bacteria isvery large in the maricultural environments. PCR methods were used to detect if these resistant bacteria carry tetracycline and sulfa resistance genes. Out of the 33 tetracycline-resistant bacteria screened, 3 were positive for tetA, 6 were positive for tetB and no isolate wasboth positive for tetA and tetB. Of the 97 sulfa-resistant bacteria screened, 9 were positive for sul2, 6 were positive for sul1, 1 isolate was positive for bothsul1 and sul2. The minimum inhibitory concentration (MIC) of tetracycline for tetA-carrying isolates were higher than those tetB-carrying isolates.while The MIC of sulfa for sul2-carrying isolates were higher than those sul1-carrying isolates. Indicating that tetA and sul2 gene may play ubknown roles in resisting tetracycline and sulfa than tetB and sul1 genes. The results showed the 4 kinds of genes (tetA,tetB,sul1,sul2) has no host specificity. All these 16S sequence are from the isolates which are positive for the above genes, it indicated the above antibiotic resistance genes are widespread in the environment regardless of the host. While the DNA sequence of these four genes showed tetA, sul1, sul2 genes are conservative in different bacteria , etB gene conserved poorly. The research aim is to get a preliminary understanding of resistance mechanism related to the resistant bacteria and the resistance genes in marine aquaculture environment through the analysis of resistant genes, providing research base for the prevention and treatment of drug-resistant bacteria so as to reduce the threat to the ecological environment, aquaculture and human health.

  4. [The importance of wildlife as reservoir of antibiotic-resistant bacteria in Bavaria--first results].

    PubMed

    Meyer, Cornelia; Heurich, Marco; Huber, Ingrid; Krause, Gladys; Ullrich, Ulrike; Fetsch, Alexandra

    2014-01-01

    The use of antimicrobial agents is responsible for the emergence and spread of antibiotic resistant bacteria. Nevertheless, multiresistant bacteria have been found in animals that have never been exposed to antimicrobial agents. Wild animals that are carriers of methicillin-resistant organisms represent a hazard since they can transmit their bacteria to other animals and to humans. In the hunting season 2009/2010 nasal swabs of 98 red deer and 109 wild boars were examined for the presence of methicillin-sensitive and methicillin-resistant staphylococci. From each wild boar methicillin-susceptible staphylococci (Staphylococcus aureus in 28% and Staphylococcus spp. in 72% of the animals) were isolated. In red deer the detection rate of Staphylococcus (S.) aureus and methicillin-susceptible staphylococci was 49% and 17%, respectively. The occurrence of S. aureus was significantly higher (p < 0.05) in red deer than in wild boars. Methicillin-resistant staphylococci were not found. However, in one third of the red deer, methicillin-resistant bacteria of the genus Enterococcus spp. and Bacillus spp. were isolated. The results of the present study indicate that wildlife, especially red deer are an important reservoir for S. aureus and that the upper respiratory tract of red deer is regularly colonised with methicillin-resistant bacteria such as Bacillus spp. and Enterococcus spp. Primarily, commensal bacteria are harmless to human health, however, red deer may be a reservoir for antibiotic-resistant bacteria.

  5. Population Screening Using Sewage Reveals Pan-Resistant Bacteria in Hospital and Community Samples

    PubMed Central

    Mileguir, Fernando; Azar, Roberto; Smollan, Gill; Belausov, Natasha; Rahav, Galia; Shamiss, Ari; Mendelson, Ella; Keller, Nathan

    2016-01-01

    The presence of pan-resistant bacteria worldwide possesses a threat to global health. It is difficult to evaluate the extent of carriage of resistant bacteria in the population. Sewage sampling is a possible way to monitor populations. We evaluated the presence of pan-resistant bacteria in Israeli sewage collected from all over Israel, by modifying the pour plate method for heterotrophic plate count technique using commercial selective agar plates. This method enables convenient and fast sewage sampling and detection. We found that sewage in Israel contains multiple pan-resistant bacteria including carbapenemase resistant Enterobacteriacae carrying blaKPC and blaNDM-1, MRSA and VRE. blaKPC carrying Klebsiella pneumonia and Enterobacter cloacae were the most common Enterobacteriacae drug resistant bacteria found in the sewage locations we sampled. Klebsiella pneumonia, Enterobacter spp., Escherichia coli and Citrobacter spp. were the 4 main CRE isolated from Israeli sewage and also from clinical samples in our clinical microbiology laboratory. Hospitals and Community sewage had similar percentage of positive samplings for blaKPC and blaNDM-1. VRE was found to be more abundant in sewage in Israel than MRSA but there were more locations positive for MRSA and VRE bacteria in Hospital sewage than in the Community. Therefore, our upgrade of the pour plate method for heterotrophic plate count technique using commercial selective agar plates can be a useful tool for routine screening and monitoring of the population for pan-resistant bacteria using sewage. PMID:27780222

  6. [Regulating acid stress resistance of lactic acid bacteria--a review].

    PubMed

    Wu, Chongde; Huang, Jun; Zhou, Rongqing

    2014-07-04

    As cell factories, lactic acid bacteria are widely used in food, agriculture, pharmaceutical and other industries. Acid stress is one the important survival challenges encountered by lactic acid bacteria both in fermentation process and in the gastrointestinal tract. Recently, the development of systems biology and metabolic engineering brings unprecedented opportunity for further elucidating the acid tolerance mechanisms and improving the acid stress resistance of lactic acid bacteria. This review addresses physiological mechanisms of lactic acid bacteria during acid stress. Moreover, strategies to improve the acid stress resistance of lactic acid were proposed.

  7. Mathematical model for the transport of fluoroquinolone and its resistant bacteria in aquatic environment.

    PubMed

    Gothwal, Ritu; Thatikonda, Shashidhar

    2017-08-05

    Development of antibiotic resistance in environmental bacteria is a direct threat to public health. Therefore, it becomes necessary to understand the fate and transport of antibiotic and its resistant bacteria. This paper presents a mathematical model for spatial and temporal transport of fluoroquinolone and its resistant bacteria in the aquatic environment of the river. The model includes state variables for organic matter, fluoroquinolone, heavy metals, and susceptible and resistant bacteria in the water column and sediment bed. Resistant gene is the factor which makes bacteria resistant to a particular antibiotic and is majorly carried on plasmids. Plasmid-mediated resistance genes are transferable between different bacterial species through conjugation (horizontal resistance transfer). This model includes plasmid dynamics between susceptible and resistant bacteria by considering the rate of horizontal resistance gene transfer among bacteria and the rate of losing resistance (segregation). The model describes processes which comprise of advection, dispersion, degradation, adsorption, diffusion, settling, resuspension, microbial growth, segregation, and transfer of resistance genes. The mathematical equations were solved by using numerical methods (implicit-explicit scheme) with appropriate boundary conditions. The development of the present model was motivated by the fact that the Musi River is heavily impacted by antibiotic pollution which led to the development of antibiotic resistance in its aquatic environment. The model was simulated for hypothetical pollution scenarios to predict the future conditions under various pollution management alternatives. The simulation results of the model for different cases show that the concentration of antibiotic, the concentration of organic matter, segregation rate, and horizontal transfer rate are the governing factors in the variation of population density of resistant bacteria. The treatment of effluents for

  8. Distribution and quantification of antibiotic resistant genes and bacteria across agricultural and non-agricultural metagenomes.

    PubMed

    Durso, Lisa M; Miller, Daniel N; Wienhold, Brian J

    2012-01-01

    There is concern that antibiotic resistance can potentially be transferred from animals to humans through the food chain. The relationship between specific antibiotic resistant bacteria and the genes they carry remains to be described. Few details are known about the ecology of antibiotic resistant genes and bacteria in food production systems, or how antibiotic resistance genes in food animals compare to antibiotic resistance genes in other ecosystems. Here we report the distribution of antibiotic resistant genes in publicly available agricultural and non-agricultural metagenomic samples and identify which bacteria are likely to be carrying those genes. Antibiotic resistance, as coded for in the genes used in this study, is a process that was associated with all natural, agricultural, and human-impacted ecosystems examined, with between 0.7 to 4.4% of all classified genes in each habitat coding for resistance to antibiotic and toxic compounds (RATC). Agricultural, human, and coastal-marine metagenomes have characteristic distributions of antibiotic resistance genes, and different bacteria that carry the genes. There is a larger percentage of the total genome associated with antibiotic resistance in gastrointestinal-associated and agricultural metagenomes compared to marine and Antarctic samples. Since antibiotic resistance genes are a natural part of both human-impacted and pristine habitats, presence of these resistance genes in any specific habitat is therefore not sufficient to indicate or determine impact of anthropogenic antibiotic use. We recommend that baseline studies and control samples be taken in order to determine natural background levels of antibiotic resistant bacteria and/or antibiotic resistance genes when investigating the impacts of veterinary use of antibiotics on human health. We raise questions regarding whether the underlying biology of each type of bacteria contributes to the likelihood of transfer via the food chain.

  9. Distribution and Quantification of Antibiotic Resistant Genes and Bacteria across Agricultural and Non-Agricultural Metagenomes

    PubMed Central

    Durso, Lisa M.; Miller, Daniel N.; Wienhold, Brian J.

    2012-01-01

    There is concern that antibiotic resistance can potentially be transferred from animals to humans through the food chain. The relationship between specific antibiotic resistant bacteria and the genes they carry remains to be described. Few details are known about the ecology of antibiotic resistant genes and bacteria in food production systems, or how antibiotic resistance genes in food animals compare to antibiotic resistance genes in other ecosystems. Here we report the distribution of antibiotic resistant genes in publicly available agricultural and non-agricultural metagenomic samples and identify which bacteria are likely to be carrying those genes. Antibiotic resistance, as coded for in the genes used in this study, is a process that was associated with all natural, agricultural, and human-impacted ecosystems examined, with between 0.7 to 4.4% of all classified genes in each habitat coding for resistance to antibiotic and toxic compounds (RATC). Agricultural, human, and coastal-marine metagenomes have characteristic distributions of antibiotic resistance genes, and different bacteria that carry the genes. There is a larger percentage of the total genome associated with antibiotic resistance in gastrointestinal-associated and agricultural metagenomes compared to marine and Antarctic samples. Since antibiotic resistance genes are a natural part of both human-impacted and pristine habitats, presence of these resistance genes in any specific habitat is therefore not sufficient to indicate or determine impact of anthropogenic antibiotic use. We recommend that baseline studies and control samples be taken in order to determine natural background levels of antibiotic resistant bacteria and/or antibiotic resistance genes when investigating the impacts of veterinary use of antibiotics on human health. We raise questions regarding whether the underlying biology of each type of bacteria contributes to the likelihood of transfer via the food chain. PMID:23133629

  10. Perinatal vertical transmission of antibiotic-resistant bacteria: a systematic review and proposed research strategy.

    PubMed

    Seale, J; Millar, M

    2014-07-01

    Antibiotic-resistant bacteria contribute to both early- and late-onset sepsis and outbreaks in neonatal intensive care units (NICUs). The extent to which vertical transmission of these resistant bacteria contributes to colonisation or infection of vulnerable infants in NICUs is unclear. Risk factors for vertical transmission of antibiotic-resistant bacteria are not well described. To identify studies describing vertical transmission of antibiotic-resistant bacteria, risk factors for transmission and the impact of colonisation on neonatal outcomes. EMBASE, CINAHL, Cochrane, PubMed, and MEDLINE databases were searched using selected terminology. Titles and abstracts were screened by two reviewers. Selected papers were reviewed in full by two individuals to ascertain whether they fulfilled the inclusion criteria. Any original article investigating perinatal vertical transmission of antibiotic-resistant bacteria between a mother and neonate was included. Data were extracted on study design, organism, antibiotic resistance, and means of ascertaining vertical transmission. Five papers out of 4839 titles fulfilled the inclusion criteria. Four studies were predominantly observational and one was a case report. Each demonstrated perinatal transmission. No study reported risk factors for the transmission of resistant bacteria or the impact of colonisation on neonatal outcomes. There is an absence of research into the perinatal transmission of resistant organisms despite the potential implications of such a situation. We outline objectives that need to be addressed in future research and describe a study design to ascertain the prevalence and risk factors for vertical transmission. © 2014 Royal College of Obstetricians and Gynaecologists.

  11. Analysis of antimicrobial resistance mechanisms in MDR bacteria by microarray and high-throughput sequencing

    USDA-ARS?s Scientific Manuscript database

    Antimicrobial resistance in pathogenic bacteria is a major concern in human and animal health. The National Antimicrobial Resistance Monitoring System (NARMS) was designed by the CDC, FDA, and USDA to monitor antimicrobial resistance in the U.S. The Bacterial Epidemiology and Antimicrobial Resistanc...

  12. Control of antibiotic-resistant bacteria: Memorandum from a WHO Meeting*

    PubMed Central

    1983-01-01

    Control of the prevalence of antibiotic-resistant bacteria is essential for the appropriate use of antibiotics for prophylaxis and treatment of infections. Hospitals are regarded as the place where antibiotic-resistant bacteria might often develop. Control of antibiotic use in hospitals is therefore one of the most important measures for effective control of antibiotic resistance. Another effective means to control antibiotic resistance is to develop a surveillance programme on a national, and international scale. This would be of great assistance, especially for forecasting future changes in the resistance of bacteria. The prevention of disease by measures other than the use of antibiotics could also reduce antibiotic resistance. This Memorandum of the WHO Scientific Working Group on Antibiotic Resistance describes the measures for controlling the prevalence of antibiotic-resistant bacteria by (a) the surveillance of antibiotic resistance, including surveillance of resistance in human pathogens and resistance determinants in the general population, and (b) control of antibiotic use in hospitals, the essential elements of which are the establishment of appropriate hospital antibiotic policy, elaboration of general strategy, and the monitoring of antibiotic use. Further research needs are also described and a number of areas are indicated where research might lead to improvements in antibiotic use and in methods for the containment of resistance. Guidelines for the appropriate use of antibiotics are presented in an Annex. PMID:6603916

  13. Distribution and quantification of antibiotic resistance genes and bacteria across agricultural and non-agricultural metagenomes

    USDA-ARS?s Scientific Manuscript database

    There is concern that antibiotic resistance can potentially be transferred from animals to humans through the food chain. The relationship between specific antibiotic resistant bacteria and the genes they carry remains to be described and few details are known about how antibiotic resistance genes i...

  14. Presence of antimicrobial resistance in coliform bacteria from hatching broiler eggs with emphasis on ESBL/AmpC-producing bacteria.

    PubMed

    Mezhoud, H; Chantziaras, I; Iguer-Ouada, M; Moula, N; Garmyn, A; Martel, A; Touati, A; Smet, A; Haesebrouck, F; Boyen, F

    2016-08-01

    Antimicrobial resistance is recognized as one of the most important global health challenges. Broilers are an important reservoir of antimicrobial resistant bacteria in general and, more particularly, extended-spectrum β-lactamases (ESBL)/AmpC-producing Enterobacteriaceae. Since contamination of 1-day-old chicks is a potential risk factor for the introduction of antimicrobial resistant Enterobacteriaceae in the broiler production chain, the presence of antimicrobial resistant coliform bacteria in broiler hatching eggs was explored in the present study. Samples from 186 hatching eggs, collected from 11 broiler breeder farms, were inoculated on MacConkey agar with or without ceftiofur and investigated for the presence of antimicrobial resistant lactose-positive Enterobacteriaceae, particularly, ESBL/AmpC-producers. Escherichia coli and Enterobacter cloacae were obtained from the eggshells in 10 out of 11 (10/11) sampled farms. The majority of the isolates were recovered from crushed eggshells after external decontamination suggesting that these bacteria are concealed from the disinfectants in the egg shell pores. Antimicrobial resistance testing revealed that approximately 30% of the isolates showed resistance to ampicillin, tetracycline, trimethoprim and sulphonamides, while the majority of isolates were susceptible to amoxicillin-clavulanic acid, nitrofurantoin, aminoglycosides, florfenicol, neomycin and apramycin. Resistance to extended-spectrum cephalosporins was detected in eight Enterobacteriaceae isolates from five different broiler breeder farms. The ESBL phenotype was confirmed by the double disk synergy test and blaSHV-12, blaTEM-52 and blaACT-39 resistance genes were detected by PCR. This report is the first to present broiler hatching eggs as carriers and a potential source of ESBL/AmpC-producing Enterobacteriaceae for broiler chicks.

  15. Multidrug efflux pumps in Gram-negative bacteria and their role in antibiotic resistance.

    PubMed

    Blair, Jessica M A; Richmond, Grace E; Piddock, Laura J V

    2014-01-01

    Gram-negative bacteria express a plethora of efflux pumps that are capable of transporting structurally varied molecules, including antibiotics, out of the bacterial cell. This efflux lowers the intracellular antibiotic concentration, allowing bacteria to survive at higher antibiotic concentrations. Overexpression of some efflux pumps can cause clinically relevant levels of antibiotic resistance in Gram-negative pathogens. This review discusses the role of efflux in resistance of clinical isolates of Gram-negative bacteria, the regulatory mechanisms that control efflux pump expression, the recent advances in our understanding of efflux pump structure and how inhibition of efflux is a promising future strategy for tackling multidrug resistance in Gram-negative pathogens.

  16. [Selection and spreading of antibiotic resistance in bacteria].

    PubMed

    Frimodt-Møller, Niels; Kolmos, Hans Jørn

    2011-11-07

    Use of an antibiotic may not only select for resistance against the agent itself, but may at the same time co-select for resistance against other antibiotics if resistance genes are linked on e.g. a plasmid. Resistance plasmids may also carry genes mediating resistance against metals and disinfectants. Therefore, abundant use of metals, e.g. copper and zinc for growth promotion in animals used for food, may also co-select for antibiotic resistance. The same applies to disinfectants, e.g. silver and chlorhexidine. Prudent use of antibiotics and these other agents is essential to control antibiotic resistance.

  17. Irrigation waters and pipe-based biofilms as sources for antibiotic-resistant bacteria.

    PubMed

    Blaustein, Ryan A; Shelton, Daniel R; Van Kessel, Jo Ann S; Karns, Jeffrey S; Stocker, Matthew D; Pachepsky, Yakov A

    2016-01-01

    The presence of antibiotic-resistant bacteria in environmental surface waters has gained recent attention. Wastewater and drinking water distribution systems are known to disseminate antibiotic-resistant bacteria, with the biofilms that form on the inner-surfaces of the pipeline as a hot spot for proliferation and gene exchange. Pipe-based irrigation systems that utilize surface waters may contribute to the dissemination of antibiotic-resistant bacteria in a similar manner. We conducted irrigation events at a perennial stream on a weekly basis for 1 month, and the concentrations of total heterotrophic bacteria, total coliforms, and fecal coliforms, as well as the concentrations of these bacterial groups that were resistant to ampicillin and tetracycline, were monitored at the intake water. Prior to each of the latter three events, residual pipe water was sampled and 6-in. sections of pipeline (coupons) were detached from the system, and biofilm from the inner-wall was removed and analyzed for total protein content and the above bacteria. Isolates of biofilm-associated bacteria were screened for resistance to a panel of seven antibiotics, representing five antibiotic classes. All of the monitored bacteria grew substantially in the residual water between irrigation events, and the biomass of the biofilm steadily increased from week to week. The percentages of biofilm-associated isolates that were resistant to antibiotics on the panel sometimes increased between events. Multiple-drug resistance was observed for all bacterial groups, most often for fecal coliforms, and the distributions of the numbers of antibiotics that the total coliforms and fecal coliforms were resistant to were subject to change from week to week. Results from this study highlight irrigation waters as a potential source for antibiotic-resistant bacteria, which can subsequently become incorporated into and proliferate within irrigation pipe-based biofilms.

  18. Surprising Alteration of Antibacterial Activity of 5″-Modified Neomycin against Resistant Bacteria

    PubMed Central

    Zhang, Jianjun; Chiang, Fang-I; Wu, Long; Czyryca, Przemyslaw Greg; Li, Ding; Chang, Cheng-Wei Tom

    2009-01-01

    A facile synthetic protocol for the production of neomycin B derivatives with various modifications at the 5″ position has been developed. Structural activity relationship (SAR) against aminoglycoside resistant bacteria equipped with various aminoglycoside-modifying enzymes (AME's) was investigated. Enzymatic and molecular modeling studies reveal that the superb substrate promiscuity of AME's allows the resistant bacteria to cope with diverse structural modifications despite the observation that several derivatives show enhanced antibacterial activity than the parent neomycin. Surprisingly, when testing synthetic neomycin derivatives against other human pathogens, two leads exhibit prominent activity against both Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) that are known to exert high level of resistance against clinically used aminoglycosides. These findings can be extremely useful in developing new aminoglycoside antibiotics against resistant bacteria. Our result also suggests that new biological and antimicrobial activities can be obtained by chemical modifications of old drugs. PMID:19012394

  19. Occurrence of ceftriaxone-resistant commensal bacteria on a dairy farm and a poultry farm.

    PubMed

    Yang, Hua; Dettman, Brittany; Beam, Jonathan; Mix, Caroline; Jiang, Xiuping

    2006-10-01

    Approximately 40 samples of animal feces, drinking water, feed, bedding, pine wood shavings, compost, and manure slurry were collected from two animal research farms (one dairy and one poultry) and analyzed for ceftriaxone-resistant bacteria. Our study revealed that the total percentage of aerobic bacteria with reduced susceptibility to ceftriaxone (minimal inhibitory concentration (MIC) > or = 16 micro g/mL) ranged from 0.9% to 10.8% in dairy feces and from 0.05% to 3.93% in chicken feces. The percentages of ceftriaxone-resistant bacteria (MIC > or = 64 micro g/mL) were in the range of 0.01% - 2.3% in dairy feces and 0.01% - 0.79% in chicken feces. Environmental samples contained a wide range of ceftriaxone-resistant bacterial populations. Among those environmental samples, fresh pine wood shavings used as chicken bedding contained the highest percentages (41.5%) of ceftriaxone-resistant bacteria, as determined by a plating method. A total of 105 ceftriaxone-resistant (MIC > or = 128 micro g/mL) bacterial isolates were isolated from the above samples and tested for resistance to nine antibiotics: ampicillin, ceftriaxone, streptomycin, kanamycin, gentamicin, chloramphenicol, tetracycline, ciprofloxacin, and nalidixic acid. The most prevalent resistance pattern (34.3%) among isolates included resistance to all nine antibiotics. Results from this study suggest that ceftriaxone-resistant bacteria exist in farm environments, and the ceftriaxone resistance was frequently associated with resistance to multiple antibiotics. Environmental sources such as pine wood shavings used as bedding can be a potential reservoir for transmitting the multidrug-resistant bacteria.

  20. Amoeba-resisting bacteria and ventilator-associated pneumonia.

    PubMed

    La Scola, Bernard; Boyadjiev, Ioanna; Greub, Gilbert; Khamis, Atieh; Martin, Claude; Raoult, Didier

    2003-07-01

    To evaluate the role of amoeba-associated bacteria as agents of ventilator-associated pneumonia (VAP), we tested the water from an intensive care unit (ICU) every week for 6 months for such bacteria isolates; serum samples and bronchoalveolar lavage samples (BAL) were also obtained from 30 ICU patients. BAL samples were examined for amoeba-associated bacteria DNA by suicide-polymerase chain reaction, and serum samples were tested against ICU amoeba-associated bacteria. A total of 310 amoeba-associated bacteria from 10 species were isolated. Twelve of 30 serum samples seroconverted to one amoeba-associated bacterium isolated in the ICU, mainly Legionella anisa and Bosea massiliensis, the most common isolates from water (p=0.021). Amoeba-associated bacteria DNA was detected in BAL samples from two patients whose samples later seroconverted. Seroconversion was significantly associated with VAP and systemic inflammatory response syndrome, especially in patients for whom no etiologic agent was found by usual microbiologic investigations. Amoeba-associated bacteria might be a cause of VAP in ICUs, especially when microbiologic investigations are negative.

  1. Amoeba-Resisting Bacteria and Ventilator-Associated Pneumonia

    PubMed Central

    La Scola, Bernard; Boyadjiev, Ioanna; Greub, Gilbert; Khamis, Atieh; Martin, Claude

    2003-01-01

    To evaluate the role of amoeba-associated bacteria as agents of ventilator-associated pneumonia (VAP), we tested the water from an intensive care unit (ICU) every week for 6 months for such bacteria isolates; serum samples and bronchoalveolar lavage samples (BAL) were also obtained from 30 ICU patients. BAL samples were examined for amoeba-associated bacteria DNA by suicide-polymerase chain reaction, and serum samples were tested against ICU amoeba-associated bacteria. A total of 310 amoeba-associated bacteria from10 species were isolated. Twelve of 30 serum samples seroconverted to one amoeba-associated bacterium isolated in the ICU, mainly Legionella anisa and Bosea massiliensis, the most common isolates from water (p=0.021). Amoeba-associated bacteria DNA was detected in BAL samples from two patients whose samples later seroconverted. Seroconversion was significantly associated with VAP and systemic inflammatory response syndrome, especially in patients for whom no etiologic agent was found by usual microbiologic investigations. Amoeba-associated bacteria might be a cause of VAP in ICUs, especially when microbiologic investigations are negative. PMID:12890321

  2. Antibiotic resistance of bacteria isolated from heavy metal-polluted soils with different land uses.

    PubMed

    Safari Sinegani, Ali Akbar; Younessi, Nayereh

    2017-09-01

    The main objective of this study was to determine the relationship between the antibiotic and heavy metal tolerance of culturable bacteria isolated from mining waste, pasture, and agricultural soils containing different levels of heavy metals. The populations of total culturable bacteria, and heavy metal- and antibiotic-tolerant bacteria in the soils were enumerated on nutrient agar, nutrient agar amended with metals, and Mueller-Hinton agar amended with antibiotics, respectively. The multiple antibiotic resistance index, and patterns of antibiotic resistance and heavy metal-antibiotic co-resistance were determined for 237 isolates. Among all the samples, those of the tailings of mines with higher levels of heavy metals had the lowest number of bacteria, but a relatively higher abundance of heavy metal- and antibiotic-resistant bacteria. A high degree of resistance was observed for ampicillin and amoxicillin in the isolates from all soils. The agricultural soil isolates had a high prevalence of resistance towards vancomycin, tetracycline, and streptomycin. Among all the tested antibiotics, gentamicin was the most potent. The most frequent pattern of multiple antibiotic resistance in the isolates from agricultural soils was amoxicillin, ampicillin, streptomycin, vancomycin, tetracycline, and doxycycline. The percentage of isolates with multiple antibiotic resistance was considerably higher in the agricultural soils than in the mining waste soils. A high rate of co-resistance towards Hg and antibiotics was observed among the gram-negative isolates, and towards Zn, Ni, Hg, and the beta-lactam antibiotics among the gram-positive isolates. The higher percentage of isolates with multiple antibiotic resistance in the agricultural soils that in the mining waste soils may be related to (1) the level of soil heavy metals, (2) the population and diversity of soil bacteria, (3) the application of manures, and (4) other factors affecting gene transfer between bacteria

  3. A bioinformatic approach to understanding antibiotic resistance in intracellular bacteria through whole genome analysis.

    PubMed

    Biswas, Silpak; Raoult, Didier; Rolain, Jean-Marc

    2008-09-01

    Intracellular bacteria survive within eukaryotic host cells and are difficult to kill with certain antibiotics. As a result, antibiotic resistance in intracellular bacteria is becoming commonplace in healthcare institutions. Owing to the lack of methods available for transforming these bacteria, we evaluated the mechanisms of resistance using molecular methods and in silico genome analysis. The objective of this review was to understand the molecular mechanisms of antibiotic resistance through in silico comparisons of the genomes of obligate and facultative intracellular bacteria. The available data on in vitro mutants reported for intracellular bacteria were also reviewed. These genomic data were analysed to find natural mutations in known target genes involved in antibiotic resistance and to look for the presence or absence of different resistance determinants. Our analysis revealed the presence of tetracycline resistance protein (Tet) in Bartonella quintana, Francisella tularensis and Brucella ovis; moreover, most of the Francisella strains possessed the blaA gene, AmpG protein and metallo-beta-lactamase family protein. The presence or absence of folP (dihydropteroate synthase) and folA (dihydrofolate reductase) genes in the genome could explain natural resistance to co-trimoxazole. Finally, multiple genes encoding different efflux pumps were studied. This in silico approach was an effective method for understanding the mechanisms of antibiotic resistance in intracellular bacteria. The whole genome sequence analysis will help to predict several important phenotypic characteristics, in particular resistance to different antibiotics. In the future, stable mutants should be obtained through transformation methods in order to demonstrate experimentally the determinants of resistance in intracellular bacteria.

  4. Surveillance of Antibiotic-Resistant Bacteria from Wastewater Effluents Across the United States

    EPA Science Inventory

    This presentation will inform the audience of the purpose and importance of the antibiotic resistant bacteria surveillances that have been conducted to date. And an overview of why the EPA is looking into this problem in wastewater effluents.

  5. Surveillance of Antibiotic-Resistant Bacteria from Wastewater Effluents Across the United States

    EPA Science Inventory

    This presentation will inform the audience of the purpose and importance of the antibiotic resistant bacteria surveillances that have been conducted to date. And an overview of why the EPA is looking into this problem in wastewater effluents.

  6. Antibiotic-resistant bacteria: prevalence in food and inactivation by food compatible compounds and plant extracts

    USDA-ARS?s Scientific Manuscript database

    Foodborne antibiotic-resistant pathogenic bacteria such as Campylobacter jejuni, Bacillus cereus, Clostridium perfringens, Escherichia coli, Salmonella enterica, Staphylococcus aureus, and Vibrio cholerae can adversely affect animal and human health, but a better understanding of the factors involve...

  7. Protist-Bacteria Associations: Gammaproteobacteria and Alphaproteobacteria Are Prevalent as Digestion-Resistant Bacteria in Ciliated Protozoa

    PubMed Central

    Gong, Jun; Qing, Yao; Zou, Songbao; Fu, Rao; Su, Lei; Zhang, Xiaoli; Zhang, Qianqian

    2016-01-01

    Protistan bacterivory, a microbial process involving ingestion and digestion, is ecologically important in the microbial loop in aquatic and terrestrial ecosystems. While bacterial resistance to protistan ingestion has been relatively well understood, little is known about protistan digestion in which some ingested bacteria could not be digested in cells of major protistan grazers in the natural environment. Here we report the phylogenetic identities of digestion-resistant bacteria (DRB) that could survive starvation and form relatively stable associations with 11 marine and one freshwater ciliate species. Using clone library and sequencing of 16S rRNA genes, we found that the protistan predators could host a high diversity of DRB, most of which represented novel bacterial taxa that have not been cultivated. The localization inside host cells, quantity, and viability of these bacteria were checked using fluorescence in situ hybridization. The DRB were affiliated with Actinobacteria, Bacteroidetes, Firmicutes, Parcubacteria (OD1), Planctomycetes, and Proteobacteria, with Gammaproteobacteria and Alphaproteobacteria being the most frequently occurring classes. The dominance of Gamma- and Alphaproteobacteria corresponds well to a previous study of Global Ocean Sampling metagenomic data showing the widespread types of bacterial type VI and IV secretion systems (T6SS and T4SS) in these two taxa, suggesting a putatively significant role of secretion systems in promoting marine protist-bacteria associations. In the DRB assemblages, opportunistic bacteria such as Alteromonadaceae, Pseudoalteromonadaceae, and Vibrionaceae often presented with high proportions, indicating these bacteria could evade protistan grazing thus persist and accumulate in the community, which, however, contrasts with their well-known rarity in nature. This begs the question whether viral lysis is significant in killing these indigestible bacteria in microbial communities. Taken together, our study on

  8. Antimicrobial resistance of zoonotic and commensal bacteria in Europe: the missing link between consumption and resistance in veterinary medicine.

    PubMed

    Garcia-Migura, Lourdes; Hendriksen, Rene S; Fraile, Lorenzo; Aarestrup, Frank M

    2014-05-14

    The emergence of resistance in food animals has been associated to the consumption of antimicrobials in veterinary medicine. Consequently, monitoring programs have been designed to monitor the occurrence of antimicrobial resistant bacteria. This study analyses the amount of antimicrobial agents used in nine European countries from 2005 to 2011, and compares by univariate analysis the correlations between consumptions of each of the following antimicrobial classes; tetracycline, penicillins, cephalosporins, quinolones and macrolides. An overview of resistance in zoonotic and commensal bacteria in Europe focusing on Salmonella, Escherichia coli, Campylobacter sp. and Enterococcus sp., during the same period of time based on monitoring programs is also assessed. With the exception of cephalosporins, linear regressions showed strong positive associations between the consumption of the four different antimicrobial classes. Substantial differences between countries were observed in the amount of antimicrobials used to produce 1 kg of meat. Moreover, large variations in proportions of resistant bacteria were reported by the different countries, suggesting differences in veterinary practice. Despite the withdrawn of a specific antimicrobial from "on farm" use, persistence over the years of bacteria resistant to this particular antimicrobial agent, was still observed. There were also differences in trends of resistance associated to specific animal species. In order to correlate the use of antimicrobial agents to the presence of resistance, surveillance of antimicrobial consumption by animal species should be established. Subsequently, intervention strategies could be designed to minimize the occurrence of resistance.

  9. Ultraviolet disinfection of antibiotic resistant bacteria and their antibiotic resistance genes in water and wastewater.

    PubMed

    McKinney, Chad W; Pruden, Amy

    2012-12-18

    Disinfection of wastewater treatment plant effluent may be an important barrier for limiting the spread of antibiotic-resistant bacteria (ARBs) and antibiotic resistance genes (ARGs). While ideally disinfection should destroy ARGs, to prevent horizontal gene transfer to downstream bacteria, little is known about the effect of conventional water disinfection technologies on ARGs. This study examined the potential of UV disinfection to damage four ARGs, mec(A), van(A), tet(A), and amp(C), both in extracellular form and present within a host ARBs: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), Escherichia coli SMS-3-5, and Pseudomonas aeruginosa 01, respectively. An extended amplicon-length quantitative polymerase chain reaction assay was developed to enhance capture of ARG damage events and also to normalize to an equivalent length of target DNA (∼1000 bp) for comparison. It was found that the two Gram-positive ARBs (MRSA and VRE) were more resistant to UV disinfection than the two Gram-negative ARBs (E. coli and P. aeruginosa). The two Gram-positive organisms also possessed smaller total genome sizes, which could also have reduced their susceptibility to UV because of fewer potential pyrimidine dimer targets. An effect of cell type on damage to ARGs was only observed in VRE and P. aeruginosa, the latter potentially because of extracellular polymeric substances. In general, damage of ARGs required much greater UV doses (200-400 mJ/cm² for 3- to 4-log reduction) than ARB inactivation (10-20 mJ/cm² for 4- to 5-log reduction). The proportion of amplifiable ARGs following UV treatment exhibited a strong negative correlation with the number of adjacent thymines (Pearson r < -0.9; p < 0.0001). ARBs surviving UV treatment were negatively correlated with total genome size (Pearson r < -0.9; p < 0.0001) and adjacent cytosines (Pearson r < -0.88; p < 0.0001) but positively correlated with adjacent thymines (Pearson r

  10. Burden of extensively drug-resistant and pandrug-resistant Gram-negative bacteria at a tertiary-care centre.

    PubMed

    Bhatt, Puneet; Tandel, Kundan; Shete, Vishal; Rathi, K R

    2015-11-01

    The emergence of resistance to multiple antimicrobial agents in Gram-negative bacteria is a significant threat to public health, as it restricts the armamentarium of the clinician against these infections. The aim of this study was to determine the burden of extensively drug-resistant (XDR) and pandrug-resistant (PDR) Gram-negative bacteria at a tertiary-care centre. Antimicrobial susceptibility testing of 1240 clinical isolates of Gram-negative bacteria obtained from various clinical samples during the study period was carried out by the Kirby-Bauer disc diffusion method. Minimum inhibitory concentration of all antibiotics including tigecycline and colistin was determined by Vitek-2 automated susceptibility testing system. Out of 1240 isolates of Gram-negative bacteria, 112 isolates (9%) were resistant to all the antibiotics tested by Kirby-Bauer disc diffusion method. This finding was corroborated by Vitek-2. In addition, Vitek-2 found that 67 isolates were resistant to all antibiotics except tigecycline and colistin. A total of 30 isolates were susceptible to only colistin, and four isolates were susceptible to only tigecycline. It was also found that six isolates (excluding five isolates of Proteus spp.) were resistant to both colistin and tigecycline. Thus, 101 (8.1%) out of 1240 isolates were XDR and 11 isolates (0.9%) were PDR. The findings of this study reveal increased burden of XDR and PDR Gram-negative bacteria in our centre. It also highlights the widespread dissemination of these bacteria in the community. This situation warrants the regular surveillance of antimicrobial resistance of Gram-negative bacteria and implementation of an efficient infection control program.

  11. High isolation rates of multidrug-resistant bacteria from water and carpets of mosques

    PubMed Central

    Mohamed Ali, Mostafa Mohamed; Alemary, Fuoad; Alrtail, Amna; Rzeg, Moftah M.; Albakush, Abdulla M.; Ghenghesh, Khalifa Sifaw

    2014-01-01

    Objective There is little information regarding the isolation of antimicrobial-resistant potentially pathogenic bacteria from water and carpets of mosques worldwide. The objective of the present investigation is to determine the bacteriological quality of water and carpets of mosques in Elkhomes city in Libya. Methods Potentially pathogenic bacteria were isolated from water samples (n=44) and dust samples from carpets (n=50) of 50 mosques in Elkhomes city, Libya, using standard bacteriological procedures. Susceptibility of isolated bacteria to antimicrobial agents was determined by the disc-diffusion method. Results Of the water samples examined, 12 (27.3%) were positive for Escherichia coli, 10 (22.7%) for Klebsiella spp., and 15 (34.1%) for other enteric bacteria. Of the dust samples of carpets examined, 6 (12%) were positive for E. coli, 33 (66%) for Klebsiella spp., and 30 (60%) for Staphylococcus spp. Multidrug resistance (MDR, resistance to three or more antimicrobial groups) was found among 48.7% (19/37) and 46.9% (30/64) of the examined enterobacteria from water and carpets, respectively, and among 66.7% (20/30) of Staphylococcus spp. from carpets. In addition, methicillin-resistant Staphylococcus aureus (MRSA) was isolated from a carpet of one mosque. Conclusion Presence of multidrug-resistant potentially pathogenic bacteria in examined water and carpets indicate that mosques as communal environments may play a role in the spread of multidrug-resistant bacteria in the community and pose a serious health risk to worshipers. PMID:25128691

  12. High isolation rates of multidrug-resistant bacteria from water and carpets of mosques.

    PubMed

    Mohamed Ali, Mostafa Mohamed; Alemary, Fuoad; Alrtail, Amna; Rzeg, Moftah M; Albakush, Abdulla M; Ghenghesh, Khalifa Sifaw

    2014-01-01

    There is little information regarding the isolation of antimicrobial-resistant potentially pathogenic bacteria from water and carpets of mosques worldwide. The objective of the present investigation is to determine the bacteriological quality of water and carpets of mosques in Elkhomes city in Libya. Potentially pathogenic bacteria were isolated from water samples (n=44) and dust samples from carpets (n=50) of 50 mosques in Elkhomes city, Libya, using standard bacteriological procedures. Susceptibility of isolated bacteria to antimicrobial agents was determined by the disc-diffusion method. Of the water samples examined, 12 (27.3%) were positive for Escherichia coli, 10 (22.7%) for Klebsiella spp., and 15 (34.1%) for other enteric bacteria. Of the dust samples of carpets examined, 6 (12%) were positive for E. coli, 33 (66%) for Klebsiella spp., and 30 (60%) for Staphylococcus spp. Multidrug resistance (MDR, resistance to three or more antimicrobial groups) was found among 48.7% (19/37) and 46.9% (30/64) of the examined enterobacteria from water and carpets, respectively, and among 66.7% (20/30) of Staphylococcus spp. from carpets. In addition, methicillin-resistant Staphylococcus aureus (MRSA) was isolated from a carpet of one mosque. Presence of multidrug-resistant potentially pathogenic bacteria in examined water and carpets indicate that mosques as communal environments may play a role in the spread of multidrug-resistant bacteria in the community and pose a serious health risk to worshipers.

  13. Populations of antibiotic-resistant coliform bacteria change rapidly in a wastewater effluent dominated stream.

    PubMed

    Akiyama, Tatsuya; Savin, Mary C

    2010-11-15

    Incomplete elimination of bacteria and pharmaceutical drugs during wastewater treatment results in the entry of antibiotics and antibiotic-resistant bacteria into receiving streams with effluent inputs. In Mud Creek in Fayetteville, AR, ofloxacin, trimethoprim, and sulfamethoxazole have been detected in water and sediment, and tetracycline has been detected in sediment downstream of treated effluent input. These antibiotics have been measured repeatedly, but at low concentrations (<1μg/L) in the stream. To determine if effluent input results in detectable and stable changes in antibiotic resistances downstream of effluent input, antibiotic resistance in Escherichia coli and total coliform bacteria in Mud Creek stream water and sediment were determined using a culture-based method. Isolated E. coli colonies were characterized for multiple antibiotic resistance (MAR) patterns on solid media and to evaluate E. coli isolate richness by amplification of a partial uidA gene followed by denaturant gradient gel electrophoresis (DGGE). Despite temporal variability, proportions of antibiotic-resistant E. coli were generally high in effluent and 640m downstream. The MAR pattern ampicillin-trimethoprim-sulfamethoxazole was associated with a DGGE profile that was detected in effluent and downstream E. coli isolates, but not upstream. Percent resistance among coliform bacteria to trimethoprim and sulfamethoxazole was higher 640m downstream compared to upstream sediment and water (with one exception). Resistance to ofloxacin was too low to analyze statistically and tetracycline resistance was fairly constant across sites. Resistances changed from 640m to 2000m downstream, although dissolved nutrient concentrations within that stream stretch resembled effluent. Antibiotic resistant bacteria are entering the stream, but resistances change within a short distance of effluent inputs, more quickly than indicated based on chemical water properties. Results illustrate the difficulty in

  14. Antibiotic-resistant heterotrophic plate count bacteria and amoeba-resistant bacteria in aquifers of the Mooi River, North West province, South Africa.

    PubMed

    Carstens, Alewyn; Bartie, Catheleen; Dennis, Rainier; Bezuidenhout, Carlos

    2014-12-01

    Groundwater in the Mooi River catchment is prone to mining, agricultural, municipal and septic tank pollution. In this study physico-chemical and microbiological parameters were determined using appropriate methods. Bacterial isolates were identified by 16S rRNA sequencing (heterotrophic plate count (HPC) bacteria and amoeba-resistant bacteria (ARB)) and multiplex polymerase chain reaction (Escherichia coli). Antibiotic resistance tests were also performed. Physico-chemical parameters were generally within target water quality ranges for drinking water. HPC bacteria ranged between 10(5) and 10(7) colony-forming units (cfu)/ml. E. coli were enumerated from Trimpark, School and Cemetery. The Blaauwbank borehole was negative for faecal streptococci. Pseudomonas spp. were most abundant in the bulk water. Opportunistic pathogens isolated included Pseudomonas aeruginosa, Acinetobacter, Aeromonas, Alcaligenes, Flavobacterium, Bacillus cereus and Mycobacterium spp. Varying patterns of antibiotic resistance were observed. Most HPC bacterial isolates were resistant to cephalothin and/or amoxicillin and a few were resistant to erythromycin and streptomycin. Pseudomonas spp. was also the most abundant ARB. Other ARBs included Alcaligenes faecalis, Ochrobactrum sp. and Achromobacter sp. ARBs were resistant to streptomycin, chloramphenicol, cephalothin, and/or amoxicillin compared to HPCs. The presence of E. coli and ARB in these groundwater sources indicates potential human health risks. These risks should be further investigated and quantified, and groundwater should be treated before use.

  15. Indirect resistance to several classes of antibiotics in cocultures with resistant bacteria expressing antibiotic-modifying or -degrading enzymes.

    PubMed

    Nicoloff, Hervé; Andersson, Dan I

    2016-01-01

    Indirect resistance (IR), the ability of an antibiotic-resistant population of bacteria to protect a susceptible population, has been previously observed for β-lactamase-producing bacteria and associated with antimicrobial treatment failures. Here, we determined whether other resistance determinants could cause IR in the presence of five other classes of antibiotics. A test was designed to detect IR and 14 antibiotic resistance genes were tested in the presence of 13 antibiotics from six classes. A bioassay was used to measure the ability of resistance-causing enzymes to decrease the concentration of active antibiotics in the medium. We confirmed IR in the presence of β-lactam antibiotics (ampicillin and mecillinam) when TEM-1A was expressed. We found that bacteria expressing antibiotic-modifying or -degrading enzymes Ere(A), Tet(X2) or CatA1 caused IR in the presence of macrolides (erythromycin and clarithromycin), tetracyclines (tetracycline and tigecycline) and chloramphenicol, respectively. IR was not observed with resistance determinants that did not modify or destroy antibiotics or with enzymes modifying aminoglycosides or degrading fosfomycin. IR was dependent on the resistance enzymes decreasing the concentration of active antibiotics in the medium, hence allowing nearby susceptible bacteria to resume growth once the antibiotic concentration fell below their MIC. IR was not limited to β-lactamase-producing bacteria, but was also caused by resistant bacteria carrying cytoplasmic antibiotic-modifying or -degrading enzymes that catalyse energy-consuming reactions requiring complex cellular cofactors. Our results suggest that IR is common and further emphasizes that coinfecting agents and the human microflora can have a negative impact during antimicrobial therapy. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  16. Distribution of drug-resistant bacteria and rational use of clinical antimicrobial agents.

    PubMed

    Zhou, Chenliang; Chen, Xiaobing; Wu, Liwen; Qu, Jing

    2016-06-01

    Open wound may lead to infection in patients. Due to overuse of medication, certain bacteria have become resistant to drugs currently available. The aim of the present study was to provide a guide to ameliorate the appropriate and rational use of clinical antimicrobial agents by analyzing the distribution of drug-resistant pathogenic bacteria in patients. Between October 2013 and January 2015, 126 patients were selected at the Department of Orthopedics. Wound secretion samples were collected, and the pathogen bacteria isolated and identified. Identification was performed using an automated identification instrument and the Kirby-Bauer antibiotic method was used to evaluate the bacterial resistance. Of the 126 patients, 118 patients were infected (infection rate, 93.65%). Additionally, 47 strains of gram-positive pathogenic bacteria (39.83%) and 71 strains of pathogenic-gram negative bacteria (60.17%) were identified. The bacteria were most likely to be resistant to penicillin while sensitive to vancomycin and imipenem. Some bacteria were resistant to several antibacterial agents. The results showed that existing risk factors at the Department of Orthopedics were complex and any non-standard procedures were able to cause bacterial infection. There were obvious dissimilarities among infectious bacteria with regard to their sensitivity to various antibacterial agents. Manipulation techniques during the treatment process were performed in a sterile manner and the use of antibacterial agents was required to be strictly in accordance with the results of drug sensitivity tests to provide effective etiologic information and a treatment plan for clinical trials and to reduce the risk of infection by multi-resistant bacteria.

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

    PubMed

    Duszyńska, Wiesława

    2010-01-01

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

  18. Effects of ultraviolet light disinfection on tetracycline-resistant bacteria in wastewater effluents.

    PubMed

    Childress, H; Sullivan, B; Kaur, J; Karthikeyan, R

    2014-09-01

    The ubiquitous use of antibiotics has led to an increasing number of antibiotic-resistant bacterial strains, including strains that are multidrug-resistant, pathogenic, or both. There is also evidence to suggest that antibiotic resistance genes (ARGs) spread to the environment, humans, and animals through wastewater effluents. The overall objective of this study was to investigate the effect of ultraviolet (UV) light disinfection on antibiotic-resistant bacteria. Wastewater effluent samples from a wastewater treatment plant (WWTP) in Texas were evaluated for differences in tetracycline-resistant bacteria before and after UV treatment. The effects of photoreactivation or dark repair on the reactivation of bacteria present in WWTP effluent after UV disinfection were also examined. Culture-based methods were used to characterize viable heterotrophic, tetracycline-resistant heterotrophic, Escherichia coli, and tetracycline-resistant E. coli bacteria present before and after UV treatment. UV disinfection was found to be as effective at reducing concentrations of resistant heterotrophs and E. coli, as it was at reducing total bacterial concentrations. The lowest survival ratio following UV disinfection was observed in tetracycline-resistant E. coli showing particular susceptibility to UV treatment. Photoreactivation and dark repair rates were found to be comparable to each other for all bacterial populations.

  19. Monitoring and evaluation of antibiotic-resistant bacteria at a municipal wastewater treatment plant in China.

    PubMed

    Huang, Jing-Jing; Hu, Hong-Ying; Lu, Sun-Qin; Li, Yi; Tang, Fang; Lu, Yun; Wei, Bin

    2012-07-01

    The prevalence of antibiotic-resistant bacteria in municipal wastewater treatment plants (WWTPs) is becoming a concern of public health. In order to acquire information on the emission of antibiotic-resistant bacteria from WWTP effluents into natural waters, both average antibiotic tolerance and concentrations of antibiotic-resistant bacteria in the effluent of a WWTP in Beijing, China were investigated. A new index of IC(50)/MIC ratio (the antibiotic concentration required to inhibit 50% of total heterotrophic bacteria compared to the highest minimum inhibitory concentration value of a group of pathogens according to a specific antibiotic, as defined by CLSI) was used to reflect the average antibiotic tolerance of total heterotrophic bacteria in the secondary effluent. The results showed that the IC(50)/MIC ratios of heterotrophic bacteria in the secondary effluent to penicillin, ampicillin, cephalothin, chloramphenicol and rifampicin were >2, >1, >1, and 1.08, respectively, which reflected a significantly high general level of heterotrophic bacteria found in the secondary effluent resistant to these five antibiotics. The concentrations of penicillin-, ampicillin-, cephalothin-, and chloramphenicol-resistant bacteria were as high as 1.5×10(4)-1.9×10(5), 1.2×10(4)-1.5×10(5), 8.9×10(3)-1.9×10(5) and 2.6×10(4)-2.0×10(5) CFU/mL, and the average percentages in relation to total heterotrophic bacteria were 63%, 47%, 55%, and 69%, respectively. The concentrations of tetracycline- and rifampicin-resistant bacteria were 840-6.1×10(3) and 310-6.1×10(4) CFU/mL with average percentages of 2.6% and 11%, respectively. Furthermore, our study found that five- and six-antibiotic-resistant bacteria were widely distributed in four types of enterobacteria from the secondary effluent. The presence of multiple-antibiotic-resistant bacteria from effluents of WWTPs into natural waters could pose a serious problem as a secondary pollutant of drinking water.

  20. Agriculture and food animals as a source of antimicrobial-resistant bacteria

    PubMed Central

    Economou, Vangelis; Gousia, Panagiota

    2015-01-01

    One of the major breakthroughs in the history of medicine is undoubtedly the discovery of antibiotics. Their use in animal husbandry and veterinary medicine has resulted in healthier and more productive farm animals, ensuring the welfare and health of both animals and humans. Unfortunately, from the first use of penicillin, the resistance countdown started to tick. Nowadays, the infections caused by antibiotic-resistant bacteria are increasing, and resistance to antibiotics is probably the major public health problem. Antibiotic use in farm animals has been criticized for contributing to the emergence of resistance. The use and misuse of antibiotics in farm animal settings as growth promoters or as nonspecific means of infection prevention and treatment has boosted antibiotic consumption and resistance among bacteria in the animal habitat. This reservoir of resistance can be transmitted directly or indirectly to humans through food consumption and direct or indirect contact. Resistant bacteria can cause serious health effects directly or via the transmission of the antibiotic resistance traits to pathogens, causing illnesses that are difficult to treat and that therefore have higher morbidity and mortality rates. In addition, the selection and proliferation of antibiotic-resistant strains can be disseminated to the environment via animal waste, enhancing the resistance reservoir that exists in the environmental microbiome. In this review, an effort is made to highlight the various factors that contribute to the emergence of antibiotic resistance in farm animals and to provide some insights into possible solutions to this major health issue. PMID:25878509

  1. Agriculture and food animals as a source of antimicrobial-resistant bacteria.

    PubMed

    Economou, Vangelis; Gousia, Panagiota

    2015-01-01

    One of the major breakthroughs in the history of medicine is undoubtedly the discovery of antibiotics. Their use in animal husbandry and veterinary medicine has resulted in healthier and more productive farm animals, ensuring the welfare and health of both animals and humans. Unfortunately, from the first use of penicillin, the resistance countdown started to tick. Nowadays, the infections caused by antibiotic-resistant bacteria are increasing, and resistance to antibiotics is probably the major public health problem. Antibiotic use in farm animals has been criticized for contributing to the emergence of resistance. The use and misuse of antibiotics in farm animal settings as growth promoters or as nonspecific means of infection prevention and treatment has boosted antibiotic consumption and resistance among bacteria in the animal habitat. This reservoir of resistance can be transmitted directly or indirectly to humans through food consumption and direct or indirect contact. Resistant bacteria can cause serious health effects directly or via the transmission of the antibiotic resistance traits to pathogens, causing illnesses that are difficult to treat and that therefore have higher morbidity and mortality rates. In addition, the selection and proliferation of antibiotic-resistant strains can be disseminated to the environment via animal waste, enhancing the resistance reservoir that exists in the environmental microbiome. In this review, an effort is made to highlight the various factors that contribute to the emergence of antibiotic resistance in farm animals and to provide some insights into possible solutions to this major health issue.

  2. Comparison of Clinical Prediction Models for Resistant Bacteria in Community-onset Pneumonia

    PubMed Central

    Self, Wesley H.; Wunderink, Richard G.; Williams, Derek J.; Barrett, Tyler W.; Baughman, Adrienne H.; Grijalva, Carlos G.

    2015-01-01

    Objectives Six recently published algorithms classify pneumonia patients presenting from the community into high- and low-risk groups for resistant bacteria. Our objective was to compare performance of these algorithms for identifying patients infected with bacteria resistant to traditional community-acquired pneumonia antibiotics. Methods This was a retrospective study of consecutive adult patients diagnosed with pneumonia in an emergency department and subsequently hospitalized. Each patient was classified as high- or low-risk for resistant bacteria according to the following algorithms: original health care-associated pneumonia (HCAP) criteria, Summit criteria, Brito and Niederman strategy, Shorr model, Aliberti model, and Shindo model. The reference for comparison was detection of resistant bacteria, defined as methicillin-resistant Staphylococcus aureus or gram-negative bacteria resistant to ceftriaxone or levofloxacin. Results Six hundred fourteen patients were studied, including 36 (5.9%) with resistant bacteria. The HCAP criteria classified 304 (49.5%) patients as high-risk, with an area under the receiver operating characteristic curve (AUC) of 0.63 (95% CI = 0.54 to 0.72), sensitivity of 0.69 (95% CI = 0.52 to 0.83), and specificity of 0.52 (95% CI = 0.48 to 0.56). None of the other algorithms improved both sensitivity and specificity, or significantly improved the AUC. Compared to the HCAP criteria, the Shorr and Aliberti models classified more patients as high-risk, resulting in higher sensitivity and lower specificity. The Shindo model classified fewer patients as high-risk, with lower sensitivity and higher specificity. Conclusions All algorithms for identification of resistant bacteria included in this study had suboptimal performance to guide antibiotic selection. New strategies for selecting empirical antibiotics for community-onset pneumonia are necessary. PMID:25996620

  3. Chlorine resistance patterns of bacteria from two drinking water distribution systems.

    PubMed Central

    Ridgway, H F; Olson, B H

    1982-01-01

    The relative chlorine sensitivities of bacteria isolated from chlorinated and unchlorinated drinking water distribution systems were compared by two independent methods. One method measured the toxic effect of free chlorine on bacteria, whereas the other measured the effect of combined chlorine. Bacteria from the chlorinated system were more resistant to both the combined and free forms of chlorine than those from the unchlorinated system, suggesting that there may be selection for more chlorine-tolerant microorganisms in chlorinated waters. Bacteria retained on the surfaces of 2.0-microns Nuclepore membrane filters were significantly more resistant to free chlorine compared to the total microbial population recovered on 0.2-micron membrane filters, presumably because aggregated cells or bacteria attached to suspended particulate matter exhibit more resistance than unassociated microorganisms. In accordance with this hypothesis, scanning electron microscopy of suspended particulate matter from the water samples revealed the presence of attached bacteria. The most resistant microorganisms were able to survive a 2-min exposure to 10 mg of free chlorine per liter. These included gram-positive spore-forming bacilli, actinomycetes, and some micrococci. The most sensitive bacteria were readily killed by chlorine concentrations of 1.0 mg liter-1 or less, and included most gram-positive micrococci, Corynebacterium/Arthrobacter, Klebsiella, Pseudomonas/Alcaligenes, Flavobacterium/Moraxella, and Acinetobacter. Images PMID:7149722

  4. Analysis on the infections change and measures for the multiple drug-resistant bacteria of neurology.

    PubMed

    Zang, Wenju

    2016-05-01

    To analyze the bacterial infection situations and the separation situations of multiple drug-resistant bacteria of the neurology of Zhengzhou People's hospital from Feb. 2012 to Dec. 2014. The patients data of neurology were retrieved by means of the doctor workstation system. The infection sites, the classification and drug-resistant feature of bacteria were classified and summarized in Excel. Finally, Compared with the infection sites, the classification and drug-resistant feature of bacteria at different year. The data obtained use SPSS 19.0 software to do statistical analysis. The infection rate of bacteria in neurology from Year 2012 to 2014 declined from 4.99% to 3.41%. But the constitution of the infection sites of bacteria had no significant changes. Staphylococcus aureus still was the majority in the infections of gram-positive bacteria, and Escherichia coli was the majority in the infections of gram-negative bacteria, and there were no significant changes in the ranking of the past three years. The separation rate of Acihetobacter baumanii and Pseudomonas aeruginosa in gram-negative bacteria gradually escalated. There were definite efficiencies in the prevention and control of the bacterial infections in neurology in the past three years. But the situation of prevention and control was still severe at the same time.

  5. Multi-drug resistant gram-negative enteric bacteria isolated from flies at Chengdu Airport, China.

    PubMed

    Liu, Yang; Yang, Yu; Zhao, Feng; Fan, Xuejun; Zhong, Wei; Qiao, Dairong; Cao, Yi

    2013-11-01

    We collected flies from Chengdu Shuangliu International Airport to examine for the presence of bacteria and to determine the sensitivity patterns of those bacteria. A total of 1,228 flies were collected from 6 sites around Chengdu Shuangliu International Airport from April to September 2011. The predominant species was Chrysomya megacephala (n=276, 22.5%). Antimicrobial-resistant gram-negative enteric bacteria (n=48) were isolated from flies using MacConkey agar supplemented with cephalothin (20 microg/ml). These were identified as Escherichia coli (n=37), Klebsiella pneumoniae (n=6), Pseudomonas aeruginosa (n=3) and Aeromonas hydrophila (n=2). All isolated bacteria were tested for resistance to 21 commonly used antimicrobials: amoxicillin (100%), ticarcillin (100%), cephalothin (100%), cefuroxime (100%), ceftazidime 1 (93.8%), piperacillin (93.8%), cefotaxime (89.6%), ticarcillin-clavulanate (81.3%), trimethoprim-sulfamethoxazole (62.5%), ciprofloxacin (54.2%), gentamicin (45.8%), cefepime (39.6%), tobramycin (39.6%), ceftazidime (22.9%), cefoxitin (16.7%), amikacin (16.7%), netilmicin (14.6%), amoxicillin-clavulanate (6.3%) and piperacillin-tazobactam (2.1%). No resistance to meropenem or imipenem was observed. Antibiotic resistance genes among the isolated bacteria were analyzed for by polymerase chain reaction. Thirty of the 48 bacteria with resistance (62.5%) possessed the blaTEM gene.

  6. Multidrug-Resistance and Toxic Metal Tolerance of Medically Important Bacteria Isolated from an Aquaculture System

    PubMed Central

    Resende, Juliana Alves; Silva, Vânia L.; Fontes, Cláudia Oliveira; Souza-Filho, Job Alves; de Oliveira, Tamara Lopes Rocha; Coelho, Cíntia Marques; César, Dionéia Evangelista; Diniz, Cláudio Galuppo

    2012-01-01

    The use of antimicrobials and toxic metals should be considered carefully in aquaculture and surrounding environments. We aimed to evaluate medically relevant bacteria in an aquaculture system and their susceptibility to antimicrobials and toxic metals. Selective cultures for enterobacteria (ENT), non-fermenting Gram-negative rods (NFR) and Gram-positive cocci (GPC) were obtained from water samples collected in two different year seasons. The isolated bacteria were biochemically identified and antimicrobial and toxic metal susceptibility patterns were determined. Overall, 407 representative strains were recovered. In general, bacteria isolated from fish ponds showed higher multiple antibiotic resistance indices when compared to those isolated from a water-fed canal. Resistance to penicillin and azithromycin was observed more frequently in the GPC group, whereas resistance to ampicillin and ampicillin/sulbactam or gentamicin was observed more frequently in the ENT and NFR groups, respectively. All the isolated bacteria were tolerant to nickel, zinc, chromium and copper at high levels (≥1,024 μg mL−1), whereas tolerance to cadmium and mercury varied among the isolated bacteria (2–1,024 μg mL−1). Multidrug-resistant bacteria were more frequent and diverse in fish ponds than in the water-fed canal. A positive correlation was observed between antimicrobial resistance and metal tolerance. The data point out the need for water treatment associated with the aquaculture system. PMID:22972388

  7. [The role of cell wall organization and active efflux pump systems in multidrug resistance of bacteria].

    PubMed

    Hasdemir, Ufuk

    2007-04-01

    Multiple antibiotic resistance of clinically important bacteria are of major concern worldwide. Alterations of drug targets or enzymatic inactivation of antimicrobial agents are the well known mechanisms of antimicrobial drug resistance. Besides these well known mechanisms, recent studies have shown that a further resistance mechanism, active drug efflux, has become increasingly important in the current threat of multidrug resistance. It involves certain bacterial transport proteins which pump out toxic antimicrobial compounds from the cell. Drug efflux pump proteins in bacteria fall into five distinct protein super families [ATP binding cassette super family (ABC), Major facilitator super family (MFS), Small multidrug resistance super family (SMR), Multidrug and toxic compound extrusion (MATE) super family, Resistance-nodulation-cell division (RND) super family] and are mostly encoded by chromosomal genes. Among them, the members of RND protein super family are widely distrubuted in Gram negative bacteria and play siginificant role in both, intrinsic and acquired multidrug resistance of these bacteria with very wide substrate specificity. RND type multidrug efflux proteins usually function together with an outer membrane canal protein (OMP) and a membrane fusion protein (MFP) to pump out drugs. AcrAB-TolC of Escherichia coli and MexAB-OprM of Pseudomonas aeruginosa are the typical examples of these tripartite systems. They are constitutively expressed in wild type cells and play significant role in intrinsic resistance of these bacteria. However, multidrug resistance which is of major clinical significance, rises as a result of overexpression of these pump systems due to mutations and elevated levels of resistance are recorded to structurally unrelated antimicrobial drugs such as fluoroquinolones, beta-lactams, tetracyclines, chloramphenicol, trimethoprim, aminoglycosides and toxic compunds. Synthesis of RND type pump proteins are regulated by complex genetic

  8. Inactivation and reactivation of antibiotic-resistant bacteria by chlorination in secondary effluents of a municipal wastewater treatment plant.

    PubMed

    Huang, Jing-Jing; Hu, Hong-Ying; Tang, Fang; Li, Yi; Lu, Sun-Qin; Lu, Yun

    2011-04-01

    Reports state that chlorination of drinking water and wastewater affects the proportions of antibiotic-resistant bacteria by potentially assisting in microbial selection. Studies on the effect of chlorination on like species of antibiotic-resistant bacteria, however, have shown to be conflicting; furthermore, few studies have inspected the regrowth or reactivation of antibiotic-resistant bacteria after chlorination in wastewater. To understand the risks of chlorination resulting from potentially selecting for antibiotic-resistant bacteria, inactivation and reactivation rates of both total heterotrophic bacteria and antibiotic-resistant bacteria (including penicillin-, ampicillin-, tetracycline-, chloramphenicol-, and rifampicin-resistant bacteria) were examined after chlorinating secondary effluent samples from a municipal wastewater treatment plant in this study. Our experimental results indicated similar inactivation rates of both total heterotrophic bacteria and antibiotic-resistant bacteria. Microbial community composition, however, was affected by chlorination: treating samples with 10 mg Cl(2)/L for 10 min resulted in chloramphenicol-resistant bacteria accounting for nearly 100% of the microbial population in contrast to 78% before chlorination. This trend shows that chlorination contributes to selection of some antibiotic-resistant strains. Reactivation of antibiotic-resistant bacteria occurred at 2.0 mg Cl(2)/L for 10 min; specifically, chloramphenicol-, ampicillin-, and penicillin-resistant bacteria were the three prevalent groups present, and the reactivation of chloramphenicol-resistant bacteria exceeded 50%. Regrowth and reactivation of antibiotic-resistant bacteria in secondary effluents after chlorination with a long retention time could threaten public health security during wastewater reuse. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. [Detection of resistance phenotypes in gram-negative bacteria].

    PubMed

    Navarro, Ferran; Calvo, Jorge; Cantón, Rafael; Fernández-Cuenca, Felipe; Mirelis, Beatriz

    2011-01-01

    Detecting resistance in gram-negative microorganisms has a strong clinical and epidemiological impact, but there is still a great deal of debate about the most sensitive phenotypic method and whether in vitro susceptibility results should be interpreted. The present work reviews the phenotypes and mechanisms of resistance to beta-lactams, quinolones and aminoglycosides in gram-negative bacilli and also revises the different phenotypic methods used for their detection. A clinical interpretation of in vitro susceptibility results is also discussed. Extended-spectrum and inhibitor resistant beta-lactamases, AmpC type beta-lactamases and carbapenemases are thoroughly reviewed. As regards quinolones, the resistance mediated both by plasmids and by mutations in the DNA gyrase and the topoisomerase IV genes is also reviewed. This report includes resistance patterns to aminoglycosides caused by modifying enzymes. Phenotypic detection of beta-lactam resistance in Neisseria spp. and Haemophilus influenzae is also reviewed in a separate section.

  10. Drug Resistance Among Pathogenic Bacteria from Animals in Ontario

    PubMed Central

    Hariharan, H.; Barnum, D. A.; Mitchell, W. R.

    1974-01-01

    Prevalence of antimicrobial drug resistance among over 3000 clinical isolates of animal pathogens in Ontario during 1971-72 has been studied. A high number of multiple resistance patterns is prevalent among members of Enterobacteriaceae, especially Escherichia coli and Salmonella typhimurium. The most common resistance pattern among bovine strains was against not less than six drugs in common use. Among different animal species the bovine population was found to be the source of a high percentage of chloramphenicol resistant E. coli and S. typhimurium organisms. All the isolates resistant to this drug were in addition resistant to three or more other antibiotics of established therapeutic value. All the multiple resistant isolates of S. typhimurium tested had R factors and they transferred most of the resistance determinants including that for chloramphenicol to a recipient E. coli in vitro. Penicillin resistance among Staphylococcus aureus of bovine mammary origin did not appear to be high. Antimicrobial drug susceptibility patterns of staphylococci, streptococci and Corynebacterium sp indicate effective in vitro activity with many antimicrobial agents. PMID:4277443

  11. Chlortetracycline - resistant intestinal bacteria in organically-raised and feral swine

    USDA-ARS?s Scientific Manuscript database

    Organically-raised swine had high fecal populations of chlortetracycline (CTC)-resistant (growing at 64 micro g CTC/ml) Escherichia coli, Megasphaera elsdenii and anaerobe populations. By comparison, predominant CTC-resistant bacteria in feral swine feces were over 1000-fold fewer and exhibited lo...

  12. Surveillance of multidrug resistant uropathogenic bacteria in hospitalized patients in Indian

    PubMed Central

    Mishra, Monali Priyadarsini; Debata, Nagen Kumar; Padhy, Rabindra Nath

    2013-01-01

    Objective To record surveillance, antibiotic resistance of uropathogens of hospitalized patients over a period of 18 months. Methods Urine samples from wards and cabins were used for isolating urinary tract infection (UTI)-causing bacteria that were cultured on suitable selective media and identified by biochemical tests; and their antibiograms were ascertained by Kirby-Bauer's disc diffusion method, in each 6-month interval of the study period, using 18 antibiotics of five different classes. Results From wards and cabins, 1 245 samples were collected, from which 996 strains of bacteria belonging to 11 species were isolated, during April 2011 to September 2012. Two Gram-positive, Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis), and nine Gram-negative bacteria, Acinetobacter baumannii, Citrobacter sp., Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Proteus vulgaris and Pseudomonas aeruginosa were isolated. Both S. aureus and E. faecalis were vancomycin resistant, and resistant-strains of all pathogens increased in each 6-month period of study. Particularly, all Gram-negatives were resistant to nitrofurantoin and co-trimoxazole, the most preferred antibiotics of empiric therapy for UTI. Conclusions Antibiograms of 11 UTI-causing bacteria recorded in this study indicated moderately higher numbers of strains resistant to each antibiotic studied, generating the fear of precipitating fervent episodes in public health particularly with bacteria, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and S. aureus. Moreover, vancomycin resistance in strains of S. aureus and E. faecalis is a matter of concern. PMID:23620859

  13. Photodynamic inactivation of antibiotic-resistant bacteria and biofilms by hematoporphyrin monomethyl ether.

    PubMed

    Liu, Chengcheng; Hu, Min; Ma, Dandan; Lei, Jin'e; Xu, Jiru

    2016-02-01

    The worldwide increase in bacterial antibiotic resistance has led to a search for alternative antibacterial therapies. A promising approach to killing antibiotic-resistant bacteria is photodynamic antimicrobial chemotherapy, which uses light in combination with a photosensitizer to induce a phototoxic reaction. We evaluated the photodynamic inactivation (PDI) efficiency of hematoporphyrin monomethyl ether (HMME) on antibiotic-resistant bacteria and biofilms. HMME exhibited no significant dark toxicity and provided dose-dependent inactivation of antibiotic-resistant bacteria and biofilms. After incubation with 100-μM HMME and irradiation with 72-J cm(-2) white light, 4.19-7.59 log10 reductions in survival were achieved in planktonic suspension. Antibiotic-resistant strains were as susceptible to PDI in biofilms as in planktonic suspensions, but the inactivation of bacterial cells in biofilms was attenuated. In addition, gram-positive bacterial strains and biofilms were more susceptible than gram-negative strains and biofilms to the PDI effect of HMME. Thus, HMME is a promising photosensitizer for the treatment of infectious diseases caused by antibiotic-resistant bacteria, especially gram-positive bacteria.

  14. Exogenous alanine and/or glucose plus kanamycin kills antibiotic-resistant bacteria.

    PubMed

    Peng, Bo; Su, Yu-Bin; Li, Hui; Han, Yi; Guo, Chang; Tian, Yao-Mei; Peng, Xuan-Xian

    2015-02-03

    Multidrug-resistant bacteria are an increasingly serious threat to human and animal health. However, novel drugs that can manage infections by multidrug-resistant bacteria have proved elusive. Here we show that glucose and alanine abundances are greatly suppressed in kanamycin-resistant Edwardsiella tarda by GC-MS-based metabolomics. Exogenous alanine or glucose restores susceptibility of multidrug-resistant E. tarda to killing by kanamycin, demonstrating an approach to killing multidrug-resistant bacteria. The mechanism underlying this approach is that exogenous glucose or alanine promotes the TCA cycle by substrate activation, which in turn increases production of NADH and proton motive force and stimulates uptake of antibiotic. Similar results are obtained with other Gram-negative bacteria (Vibrio parahaemolyticus, Klebsiella pneumoniae, Pseudomonas aeruginosa) and Gram-positive bacterium (Staphylococcus aureus), and the results are also reproduced in a mouse model for urinary tract infection. This study establishes a functional metabolomics-based strategy to manage infection by antibiotic-resistant bacteria. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Paraben resistance in bacteria from sewage treatment plant effluents in India.

    PubMed

    Selvaraj, Krishna Kumar; Sivakumar, Senthilkumari; Sampath, Srimurali; Shanmugam, Govindaraj; Sundaresan, Umamaheswari; Ramaswamy, Babu Rajendran

    2013-01-01

    Parabens, the antimicrobial preservatives used in cosmetics, food and pharmaceuticals, are often detected in the aquatic environment. Generally, sewage treatment plants (STPs) receive community sewage containing parabens, which are ultimately released into streams/rivers. In this study, bacteria in STP effluents were evaluated for their resistance to parabens. The susceptibility was in the order of Staphylococcus aureus > Bacillus sp. >Escherichia coli > Pseudomonas aeruginosa. Gram-negative bacteria showed less susceptibility than their control and Gram-positive bacteria. Further, the bacteria were more sensitive towards butyl and ethyl parabens. Interestingly, the strains showed resistance to ≥5 mg of parabens, which is equivalent to or higher than reported environmental concentrations. The increase in paraben chain length did not enhance the susceptibility in all cases and it was understood that the activity may differ for each bacterium in the environment. This is the first profile on paraben resistance in common pathogens of Indian STPs. Paraben resistance may be developed due to continuous exposure even at sub-inhibitory and/or chronic levels in the environment and this resistance may be transferred to other pathogenic bacteria in receiving waters. Thus the study demonstrates the effectiveness of the disc diffusion method in environmental bacterial resistance assessment and addresses the risk involved in the use of parabens.

  16. Microarray-Based Detection of 90 Antibiotic Resistance Genes of Gram-Positive Bacteria

    PubMed Central

    Perreten, Vincent; Vorlet-Fawer, Lorianne; Slickers, Peter; Ehricht, Ralf; Kuhnert, Peter; Frey, Joachim

    2005-01-01

    A disposable microarray was developed for detection of up to 90 antibiotic resistance genes in gram-positive bacteria by hybridization. Each antibiotic resistance gene is represented by two specific oligonucleotides chosen from consensus sequences of gene families, except for nine genes for which only one specific oligonucleotide could be developed. A total of 137 oligonucleotides (26 to 33 nucleotides in length with similar physicochemical parameters) were spotted onto the microarray. The microarrays (ArrayTubes) were hybridized with 36 strains carrying specific antibiotic resistance genes that allowed testing of the sensitivity and specificity of 125 oligonucleotides. Among these were well-characterized multidrug-resistant strains of Enterococcus faecalis, Enterococcus faecium, and Lactococcus lactis and an avirulent strain of Bacillus anthracis harboring the broad-host-range resistance plasmid pRE25. Analysis of two multidrug-resistant field strains allowed the detection of 12 different antibiotic resistance genes in a Staphylococcus haemolyticus strain isolated from mastitis milk and 6 resistance genes in a Clostridium perfringens strain isolated from a calf. In both cases, the microarray genotyping corresponded to the phenotype of the strains. The ArrayTube platform presents the advantage of rapidly screening bacteria for the presence of antibiotic resistance genes known in gram-positive bacteria. This technology has a large potential for applications in basic research, food safety, and surveillance programs for antimicrobial resistance. PMID:15872258

  17. Functional Characterization of Bacteria Isolated from Ancient Arctic Soil Exposes Diverse Resistance Mechanisms to Modern Antibiotics

    PubMed Central

    Perron, Gabriel G.; Whyte, Lyle; Turnbaugh, Peter J.; Goordial, Jacqueline; Hanage, William P.; Dantas, Gautam; Desai, Michael M.

    2015-01-01

    Using functional metagenomics to study the resistomes of bacterial communities isolated from different layers of the Canadian high Arctic permafrost, we show that microbial communities harbored diverse resistance mechanisms at least 5,000 years ago. Among bacteria sampled from the ancient layers of a permafrost core, we isolated eight genes conferring clinical levels of resistance against aminoglycoside, β-lactam and tetracycline antibiotics that are naturally produced by microorganisms. Among these resistance genes, four also conferred resistance against amikacin, a modern semi-synthetic antibiotic that does not naturally occur in microorganisms. In bacteria sampled from the overlaying active layer, we isolated ten different genes conferring resistance to all six antibiotics tested in this study, including aminoglycoside, β-lactam and tetracycline variants that are naturally produced by microorganisms as well as semi-synthetic variants produced in the laboratory. On average, we found that resistance genes found in permafrost bacteria conferred lower levels of resistance against clinically relevant antibiotics than resistance genes sampled from the active layer. Our results demonstrate that antibiotic resistance genes were functionally diverse prior to the anthropogenic use of antibiotics, contributing to the evolution of natural reservoirs of resistance genes. PMID:25807523

  18. Functional characterization of bacteria isolated from ancient arctic soil exposes diverse resistance mechanisms to modern antibiotics.

    PubMed

    Perron, Gabriel G; Whyte, Lyle; Turnbaugh, Peter J; Goordial, Jacqueline; Hanage, William P; Dantas, Gautam; Desai, Michael M

    2015-01-01

    Using functional metagenomics to study the resistomes of bacterial communities isolated from different layers of the Canadian high Arctic permafrost, we show that microbial communities harbored diverse resistance mechanisms at least 5,000 years ago. Among bacteria sampled from the ancient layers of a permafrost core, we isolated eight genes conferring clinical levels of resistance against aminoglycoside, β-lactam and tetracycline antibiotics that are naturally produced by microorganisms. Among these resistance genes, four also conferred resistance against amikacin, a modern semi-synthetic antibiotic that does not naturally occur in microorganisms. In bacteria sampled from the overlaying active layer, we isolated ten different genes conferring resistance to all six antibiotics tested in this study, including aminoglycoside, β-lactam and tetracycline variants that are naturally produced by microorganisms as well as semi-synthetic variants produced in the laboratory. On average, we found that resistance genes found in permafrost bacteria conferred lower levels of resistance against clinically relevant antibiotics than resistance genes sampled from the active layer. Our results demonstrate that antibiotic resistance genes were functionally diverse prior to the anthropogenic use of antibiotics, contributing to the evolution of natural reservoirs of resistance genes.

  19. Bloom of resident antibiotic-resistant bacteria in soil following manure fertilization.

    PubMed

    Udikovic-Kolic, Nikolina; Wichmann, Fabienne; Broderick, Nichole A; Handelsman, Jo

    2014-10-21

    The increasing prevalence of antibiotic-resistant bacteria is a global threat to public health. Agricultural use of antibiotics is believed to contribute to the spread of antibiotic resistance, but the mechanisms by which many agricultural practices influence resistance remain obscure. Although manure from dairy farms is a common soil amendment in crop production, its impact on the soil microbiome and resistome is not known. To gain insight into this impact, we cultured bacteria from soil before and at 10 time points after application of manure from cows that had not received antibiotic treatment. Soil treated with manure contained a higher abundance of β-lactam-resistant bacteria than soil treated with inorganic fertilizer. Functional metagenomics identified β-lactam-resistance genes in treated and untreated soil, and indicated that the higher frequency of resistant bacteria in manure-amended soil was attributable to enrichment of resident soil bacteria that harbor β-lactamases. Quantitative PCR indicated that manure treatment enriched the blaCEP-04 gene, which is highly similar (96%) to a gene found previously in a Pseudomonas sp. Analysis of 16S rRNA genes indicated that the abundance of Pseudomonas spp. increased in manure-amended soil. Populations of other soil bacteria that commonly harbor β-lactamases, including Janthinobacterium sp. and Psychrobacter pulmonis, also increased in response to manure treatment. These results indicate that manure amendment induced a bloom of certain antibiotic-resistant bacteria in soil that was independent of antibiotic exposure of the cows from which the manure was derived. Our data illustrate the unintended consequences that can result from agricultural practices, and demonstrate the need for empirical analysis of the agroecosystem.

  20. Bloom of resident antibiotic-resistant bacteria in soil following manure fertilization

    PubMed Central

    Udikovic-Kolic, Nikolina; Wichmann, Fabienne; Broderick, Nichole A.; Handelsman, Jo

    2014-01-01

    The increasing prevalence of antibiotic-resistant bacteria is a global threat to public health. Agricultural use of antibiotics is believed to contribute to the spread of antibiotic resistance, but the mechanisms by which many agricultural practices influence resistance remain obscure. Although manure from dairy farms is a common soil amendment in crop production, its impact on the soil microbiome and resistome is not known. To gain insight into this impact, we cultured bacteria from soil before and at 10 time points after application of manure from cows that had not received antibiotic treatment. Soil treated with manure contained a higher abundance of β-lactam–resistant bacteria than soil treated with inorganic fertilizer. Functional metagenomics identified β-lactam–resistance genes in treated and untreated soil, and indicated that the higher frequency of resistant bacteria in manure-amended soil was attributable to enrichment of resident soil bacteria that harbor β-lactamases. Quantitative PCR indicated that manure treatment enriched the blaCEP-04 gene, which is highly similar (96%) to a gene found previously in a Pseudomonas sp. Analysis of 16S rRNA genes indicated that the abundance of Pseudomonas spp. increased in manure-amended soil. Populations of other soil bacteria that commonly harbor β-lactamases, including Janthinobacterium sp. and Psychrobacter pulmonis, also increased in response to manure treatment. These results indicate that manure amendment induced a bloom of certain antibiotic-resistant bacteria in soil that was independent of antibiotic exposure of the cows from which the manure was derived. Our data illustrate the unintended consequences that can result from agricultural practices, and demonstrate the need for empirical analysis of the agroecosystem. PMID:25288759

  1. Emergence of drug resistant bacteria at the Hajj: A systematic review.

    PubMed

    Leangapichart, Thongpan; Rolain, Jean-Marc; Memish, Ziad A; Al-Tawfiq, Jaffar A; Gautret, Philippe

    2017-06-24

    Hajj is the annual mass gathering of Muslims, and is a reservoir and potential source of bacterial transmission. The emergence of bacterial transmission, including multi-drug resistance (MDR) bacteria, during Hajj has not been systematically assessed. Articles in Pubmed, Scopus, and Google scholar were identified using controlled words relating to antibiotic resistance (AR) at the Hajj from January 2002 to January 2017. Eligible studies were identified by two researchers. AR patterns of bacteria were obtained for each study. We included 31 publications involving pilgrims, Hajj workers or local patients attending hospitals in Mecca, Mina, and the Medina area. Most of these publications provided antibiotic susceptibility results. Ten of them used the PCR approach to identify AR genes. MRSA carriage was reported in pilgrims and food handlers at a rate of 20%. Low rates of vancomycin-resistant gram-positive bacteria were reported in pilgrims and patients. The prevalence of third-generation cephalosporin-resistant bacteria was common in the Hajj region. Across all studies, carbapenem-resistant bacteria were detected in fewer than 10% of E.coli isolates tested but up to 100% in K. pneumoniae and A. baumannii. Colistin-resistant Salmonella enterica, including mcr-1 colistin-resistant E.coli and K.pneumoniae were only detected in the pilgrim cohorts. This study provides an overview of the prevalence of MDR bacteria at the Hajj. Pilgrims are at high risk of AR bacterial transmission and may carry and transfer these bacteria when returning to their home countries. Thus, pilgrims should be instructed by health care practitioners about hygiene practices aiming at reducing traveler's diarrhea and limited use of antibiotics during travel in order to reduce the risk of MDR bacterial transmission. Copyright © 2017. Published by Elsevier Ltd.

  2. Global aspects of antimicrobial-resistant enteric bacteria.

    PubMed

    Kariuki, S; Hart, C A

    2001-10-01

    Antibiotics have been considered to be safe and effective 'magic bullets', with no disadvantages to their widespread use. This has been proven to be a complacent attitude, with ever-increasing prevalences of resistance now evident. The present review covers aspects of the development, mechanisms and genetics of antimicrobial resistance in enteric commensals and pathogens.

  3. Drug Resistance Mechanisms in Bacteria Causing Sexually Transmitted Diseases and Associated with Vaginosis

    PubMed Central

    Shaskolskiy, Boris; Dementieva, Ekaterina; Leinsoo, Arvo; Runina, Anastassia; Vorobyev, Denis; Plakhova, Xenia; Kubanov, Alexey; Deryabin, Dmitrii; Gryadunov, Dmitry

    2016-01-01

    Here, we review sexually transmitted diseases (STDs) caused by pathogenic bacteria and vaginal infections which result from an overgrowth of opportunistic bacterial microflora. First, we describe the STDs, the corresponding pathogens and the antimicrobials used for their treatment. In addition to the well-known diseases caused by single pathogens (i.e., syphilis, gonococcal infections, and chlamydiosis), we consider polymicrobial reproductive tract infections (especially those that are difficult to effectively clinically manage). Then, we summarize the biochemical mechanisms that lead to antimicrobial resistance and the most recent data on the emergence of drug resistance in STD pathogens and bacteria associated with vaginosis. A large amount of research performed in the last 10–15 years has shed light on the enormous diversity of mechanisms of resistance developed by bacteria. A detailed understanding of the mechanisms of antimicrobials action and the emergence of resistance is necessary to modify existing drugs and to develop new ones directed against new targets. PMID:27242760

  4. Drug Resistance Mechanisms in Bacteria Causing Sexually Transmitted Diseases and Associated with Vaginosis.

    PubMed

    Shaskolskiy, Boris; Dementieva, Ekaterina; Leinsoo, Arvo; Runina, Anastassia; Vorobyev, Denis; Plakhova, Xenia; Kubanov, Alexey; Deryabin, Dmitrii; Gryadunov, Dmitry

    2016-01-01

    Here, we review sexually transmitted diseases (STDs) caused by pathogenic bacteria and vaginal infections which result from an overgrowth of opportunistic bacterial microflora. First, we describe the STDs, the corresponding pathogens and the antimicrobials used for their treatment. In addition to the well-known diseases caused by single pathogens (i.e., syphilis, gonococcal infections, and chlamydiosis), we consider polymicrobial reproductive tract infections (especially those that are difficult to effectively clinically manage). Then, we summarize the biochemical mechanisms that lead to antimicrobial resistance and the most recent data on the emergence of drug resistance in STD pathogens and bacteria associated with vaginosis. A large amount of research performed in the last 10-15 years has shed light on the enormous diversity of mechanisms of resistance developed by bacteria. A detailed understanding of the mechanisms of antimicrobials action and the emergence of resistance is necessary to modify existing drugs and to develop new ones directed against new targets.

  5. Stress responses as determinants of antimicrobial resistance in Gram-negative bacteria.

    PubMed

    Poole, Keith

    2012-05-01

    Bacteria encounter a myriad of potentially growth-compromising conditions in nature and in hosts of pathogenic bacteria. These 'stresses' typically elicit protective and/or adaptive responses that serve to enhance bacterial survivability. Because they impact upon many of the same cellular components and processes that are targeted by antimicrobials, adaptive stress responses can influence antimicrobial susceptibility. In targeting and interfering with key cellular processes, antimicrobials themselves are 'stressors' to which protective stress responses have also evolved. Cellular responses to nutrient limitation (nutrient stress), oxidative and nitrosative stress, cell envelope damage (envelope stress), antimicrobial exposure and other growth-compromising stresses, have all been linked to the development of antimicrobial resistance in Gram-negative bacteria - resulting from the stimulation of protective changes to cell physiology, activation of resistance mechanisms, promotion of resistant lifestyles (biofilms), and induction of resistance mutations.

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

    PubMed

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

    2017-02-28

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

  7. [Significance of efflux pumps in multidrug resistance of Gram-negative bacteria].

    PubMed

    Wiercińska, Olga; Chojecka, Agnieszka; Kanclerski, Krzysztof; Rőhm-Rodowald, Ewa; Jakimiak, Bożenna

    2015-01-01

    The phenomenon of multidrug. resistance of bacteria is a serious problem of modern medicine. This resistance largely is a consequence of abuse and improper use of antibacterial substances, especially antibiotics and chemotherapeutics in hospital settings. Multidrug resistance is caused by a number of interacting mechanisms of resistance. Recent studies have indicated that efflux pumps and systems of efflux pumps are an important determinant of this phenomenon. Contribute to this particular RND efflux systems of Gram-negative bacteria, which possess a wide range of substrates such as antibiotics, dyes, detergents, toxins and active substances of disinfectants and antiseptics. These transporters are usually encoded on bacterial chromosomes. Genes encoding efflux pumps' proteins may also be carried on plasmids and other mobile genetic elements. Such pumps are usually specific to a small group of substrates, but as an additional mechanism of resistance may contribute to the multidrug resistance.

  8. Isolation and identification of cobalt- and caesium-resistant bacteria from a nuclear fuel storage pond.

    PubMed

    Dekker, Linda; Osborne, Thomas H; Santini, Joanne M

    2014-10-01

    One of the issues facing the nuclear power industry is how to store spent nuclear fuel which is contaminated with radionuclides produced during nuclear fission, including caesium ((134)Cs(+), (135)Cs(+) and (137)Cs(+)) and cobalt ((60)Co(2+)). In this study, we have isolated Co(2+)- and Cs(+)-resistant bacteria from water collected from a nuclear fuel storage pond. The most resistant Cs(+) and Co(2+) isolates grew in the presence of 500 mM CsCl and 3 mM CoCl2. Strain Cs67-2 is resistant to fourfold more Cs(+) than Cupriavidus metallidurans str. CH34 making it the most Cs(+)-resistant strain identified to date. The Cs(+)-resistant isolates were closely related to bacteria in the Serratia and Yersinia genera, while the Co(2+)-resistant isolates were closely related to the Curvibacter and Tardiphaga genera. These new isolates could be used for bioremediation.

  9. Occurrence of antibiotic resistance genes in culturable bacteria isolated from Turkish trout farms and their local aquatic environment.

    PubMed

    Capkin, Erol; Terzi, Ertugrul; Altinok, Ilhan

    2015-05-21

    Antibiotic resistance and presence of the resistance genes were investigated in the bacteria isolated from water, sediment, and fish in trout farms. A total of 9 bacterial species, particularly Escherichia coli, were isolated from the water and sediment samples, and 12 species were isolated from fish. The antimicrobial test indicated the highest resistance against sulfamethoxazole and ampicillin in coliform bacteria, and against sulfamethoxazole, imipenem, and aztreonam in known pathogenic bacteria isolated from fish. The most effective antibiotics were rifampicin, chloramphenicol, and tetracycline. The multiple antibiotic resistance index was above the critical limit for almost all of the bacteria isolated. The most common antibiotic resistance gene was ampC, followed by tetA, sul2, blaCTX-M1, and blaTEM in the coliform bacteria. At least one resistance gene was found in 70.8% of the bacteria, and 66.6% of the bacteria had 2 or more resistance genes. Approximately 36.54% of the bacteria that contain plasmids were able to transfer them to other bacteria. The plasmid-mediated transferable resistance genes were ampC, blaCTX-M1, tetA, sul2, and blaTEM. These results indicate that the aquatic environment could play an important role in the development of antibiotic resistance and the dissemination of resistance genes among bacteria.

  10. Coexistence of antibiotic-producing and antibiotic-sensitive bacteria in biofilms is mediated by resistant bacteria.

    PubMed

    Narisawa, Naoki; Haruta, Shin; Arai, Hiroyuki; Ishii, Masaharu; Igarashi, Yasuo

    2008-06-01

    Antibiotic-sensitive bacteria have been found to coexist with antibiotic-producing bacteria in biofilms, but little is known about how the former develop in such an environment. Here we isolated pyocyanin-sensitive bacteria belonging to the genus Brevibacillus from a biofilm derived from soil extract and based on the preestablished biofilm of a pyocyanin producer, Pseudomonas aeruginosa strain P1. In addition, pyocyanin-resistant strains belonging to the genus Raoultella were isolated from the same biofilm. Microbial relationships within biofilms were examined by using three strains, strain P1, Brevibacillus strain S1, and Raoultella strain R1, each of which individually formed a biofilm within 2 days in a flow cell. Strain S1 did not fully develop on the preestablished biofilm of strain P1 during 4 days of cultivation, whereas a mutant of strain P1 which was deficient in pyocyanin production allowed strain S1 to cocolonize within a biofilm. On the other hand, strain R1 developed on the biofilm of strain P1 regardless of pyocyanin production. When mixed 1:1 inocula of strains S1 and R1 were introduced into the strain P1 biofilm, all three species were found in the 4-day biofilm. In the mixed biofilm, strain S1 was surrounded by the layer of strain R1 and seemed to be separated from strain P1 and the outflow solution. However, strain S1 did not survive in a three-species mixed culture under planktonic conditions. These results indicate that the survival of sensitive bacteria in biofilm with a pyocyanin producer is achieved by covering them with a layer of resistant bacteria. We also evaluated the influence of antibiotic production on the producer.

  11. Isolation and screening of heavy metal resistant bacteria from wastewater: a study of heavy metal co-resistance and antibiotics resistance.

    PubMed

    Yamina, Benmalek; Tahar, Benayad; Marie Laure, Fardeau

    2012-01-01

    The uncontrolled discharges of wastes containing a large quantity of heavy metal create huge economical and healthcare burdens particularly for people living near that area. However, the bioremediation of metal pollutants from wastewater using metal-resistant bacteria is a very important aspect of environmental biotechnology. In this study, 13 heavy metal resistant bacteria were isolated from the wastewater of wadi El Harrach in the east of Algiers and characterized. These include zinc-, lead-, chromium- and cadmium-resistant bacteria. The metal-resistant isolates characterized include both Gram-negative (77%) and Gram-positive (23%) bacteria. The Minimum Inhibitory Concentration (MIC) of wastewater isolates against the four heavy metals was determined in solid media and ranged from 100 to 1,500 μg/ml. All the isolates showed co-resistance to other heavy metals and antibiotic resistance of which 15% were resistant to one antibiotic and 85% were multi- and bi-antibiotics resistant. The zinc-resistant species Micrococcus luteus was the much more heavy metal resistant. The results of toxicity tests on Vibrio fischeri showed that the DI(50) (5 min) as low as 0.1 carried away luminescence inhibition greater than 50%.

  12. Triclosan and antimicrobial resistance in bacteria: an overview.

    PubMed

    Yazdankhah, Siamak P; Scheie, Anne A; Høiby, E Arne; Lunestad, Bjørn-Tore; Heir, Even; Fotland, Tor Øystein; Naterstad, Kristine; Kruse, Hilde

    2006-01-01

    Triclosan is a widely used biocide that is considered as an effective antimicrobial agent against different microorganisms. It is included in many contemporary consumer and personal health-care products, like oral and dermal products, but also in household items, including plastics and textiles. At bactericidal concentrations, triclosan appears to act upon multiple nonspecific targets, causing disruption of bacterial cell wall functions, while at sublethal concentrations, triclosan affects specific targets. During the 1990s, bacterial isolates with reduced susceptibility to triclosan were produced in laboratory experiments by repeated exposure to sublethal concentrations of the agent. Since 2000, a number of studies have verified the occurrence of triclosan resistance amongst dermal, intestinal, and environmental microorganisms, including some of clinical relevance. Of major concern is the possibility that triclosan resistance may contribute to reduced susceptibility to clinically important antimicrobials, due to either cross-resistance or co-resistance mechanisms. Although the number of studies elucidating the association between triclosan resistance and resistance to other antimicrobials in clinical isolates has been limited, recent laboratory studies have confirmed the potential for such a link in Escherichia coli and Salmonella enterica. Thus, widespread use of triclosan may represent a potential public health risk in regard to development of concomitant resistance to clinically important antimicrobials.

  13. The Structure of Fitness Landscapes in Antibiotic-Resistant Bacteria

    NASA Astrophysics Data System (ADS)

    Deris, Barrett; Kim, Minsu; Zhang, Zhongge; Okano, Hiroyuki; Hermsen, Rutger; Gore, Jeff; Hwa, Terence

    2014-03-01

    To predict the emergence of antibiotic resistance, quantitative relations must be established between the fitness of drug-resistant organisms and the molecular mechanisms conferring resistance. We have investigated E. coli strains expressing resistance to translation-inhibiting antibiotics. We show that resistance expression and drug inhibition are linked in a positive feedback loop arising from an innate, global effect of drug-inhibited growth on gene expression. This feedback leads generically to plateau-shaped fitness landscapes and concomitantly, for strains expressing at least moderate degrees of drug resistance, gives rise to an abrupt drop in growth rates of cultures at threshold drug concentrations. A simple quantitative model of bacterial growth based on this innate feedback accurately predicts experimental observations without ad hoc parameter fitting. We describe how drug-inhibited growth rate and the threshold drug concentration (the minimum inhibitory concentration, or MIC) depend on the few biochemical parameters that characterize the molecular details of growth inhibition and drug resistance (e.g., the drug-target dissociation constant). And finally, we discuss how these parameters can shape fitness landscapes to determine evolutionary dynamics and evolvability.

  14. Acquired inducible antimicrobial resistance in Gram-positive bacteria

    PubMed Central

    Chancey, Scott T; Zähner, Dorothea; Stephens, David S

    2012-01-01

    A major contributor to the emergence of antibiotic resistance in Gram-positive bacterial pathogens is the expansion of acquired, inducible genetic elements. Although acquired, inducible antibiotic resistance is not new, the interest in its molecular basis has been accelerated by the widening distribution and often ‘silent’ spread of the elements responsible, the diagnostic challenges of such resistance and the mounting limitations of available agents to treat Gram-positive infections. Acquired, inducible antibiotic resistance elements belong to the accessory genome of a species and are horizontally acquired by transformation/recombination or through the transfer of mobile DNA elements. The two key, but mechanistically very different, induction mechanisms are: ribosome-sensed induction, characteristic of the macrolide–lincosamide–streptogramin B antibiotics and tetracycline resistance, leading to ribosomal modifications or efflux pump activation; and resistance by cell surface-associated sensing of β-lactams (e.g., oxacillin), glycopeptides (e.g., vancomycin) and the polypeptide bacitracin, leading to drug inactivation or resistance due to cell wall alterations. PMID:22913355

  15. Coincident plasmids and antimicrobial resistance in marine bacteria isolated from polluted and unpolluted Atlantic Ocean Samples

    SciTech Connect

    Baya, A.M.; Brayton, P.R.; Brown, V.L.; Grimes, D.J.; Russek-Cohen, E.; Colwell, R.R.

    1986-06-01

    Sewage effluent and outfall confluence samples were collected at the Barceloneta Regional Treatment Plant in Barceloneta, Puerto Rico; outfall confluence samples at Ocean City, Md., were also collected. Samples from uncontaminated open ocean areas served as clean-water controls. Bacteria were enriched in marine broth 2216 amended with 1 ..mu..g of one of a set of chemical selected for study per ml: nitrobenzene, dibutyl phthalate, m-cresol, o-cresol, 4-nitroaniline, bis(tributyltin) oxide, and quinone. MICs of the chemicals were determined individually for all isolates. Bacterial isolates were evaluated for resistance to nine different antibiotics and for the presence of plasmid DNA. Treated sewage was found to contain large numbers of bacteria simultaneously possessing antibiotic resistance, chemical resistance, and multiple bands of plasmic DNA. Bacteria resistant to penicillin, erythromycin, nalidixic acid, ampicillin, m-cresol, quinone, and bis(tributyltin) oxide were detected in nearly all samples, but only sewage outfall confluence samples yielded bacterial isolates that were resistant to streptomycin. Bacteria resistant to a combination of antibiotics, including kanamycin, chloramphenicol, gentamicin, and tetracycline, were isolated only from sewage effluent samples. It is concluded that bacterial isolates derived from toxic chemical wastes more frequently contain plasmid DNA and demonstrate antimicrobial resistance than do bacterial isolates from domestic sewage-impacted waters or from uncontaminated open ocean sites.

  16. Emergence of multi drug resistance among soil bacteria exposing to insecticides.

    PubMed

    Rangasamy, Kirubakaran; Athiappan, Murugan; Devarajan, Natarajan; Parray, Javid A

    2017-04-01

    Impacts of pesticide exposure on the soil microbial flora and cross resistance to antibiotics have not been well documented. Development of antibiotic resistance is a common issue among soil bacteria which are exposing to pesticides continuously at sub-lethal concentration. The present study was focused to evaluate the correlation between pesticide exposures and evolution of multi drug resistance among isolates collected from soil applied with insecticides. Twenty five insecticide (Monochrotophos) degrading bacteria were isolated from contaminated agricultural soil. The bacterial isolates Bacillus Sps, Bacillus cereus, Bacillus firmus and Bacillus thuringiensis were found to be resistant against chloramphenical, monochrotophos, ampicillin, cefotaxime, streptomycin and tetracycline antibiotics used. Involvement of plasmid in drug as well as insecticide resistant was confirmed through plasmid curing among selected bacterial strains. Bacillus Sps (MK-07), Bacillus cereus (MK-11), Bacillus firmus (MK-13) and Bacillus thuringiensis (MK-24) lost their resistant against insecticides and antibiotics once after removal of plasmid by exposing to 2% sodium dodecyl sulphate. The plasmid was transformed back to bacteria which produced similar derivatives when cultured in Minimal Salt medium (pH 7.0) supplemented with 0.4% of insecticide. Homology modeling was used to prove that organophosphorus hydrolase and able to metabolize all the antibiotics showed positive interaction with high docking score. The present study revealed that persistent of insecticides in the agricultural soil may lead to increasing development of multidrug resistance among soil bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Colonization with Multidrug-Resistant Bacteria – On the Efficiency of Local Decolonization Procedures

    PubMed Central

    Münch, Julia; Hagen, Ralf Matthias; Müller, Martin; Kellert, Viktor; Wiemer, Dorothea Franziska; Hinz, Rebecca; Schwarz, Norbert Georg; Frickmann, Hagen

    2017-01-01

    The effectiveness of a disinfectant-based decolonization strategy for multidrug-resistant bacteria like extended spectrum β-lactamase (ESBL)-positive Gram-negative bacteria with or without additional fluoroquinolon and carbapenem resistance as well as vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus was assessed. Between 2011 and 2015, 25 patients from Libya, Syria, and the Ukraine with war traumata were treated at the Bundeswehr hospital Hamburg. The patients were heavily colonized and infected with multidrug-resistant bacteria, altogether comprising 371 distinct combinations of pathogens and isolation sites. Local disinfection was assessed for effectiveness regarding successful decolonization of multidrug-resistant bacteria. Altogether, 170 cases of successful decolonization were observed, comprising 95 (55.8%) such events at sampling sites that were accessible to disinfecting procedures. The remaining 75 (44.2%) decolonization events had to be considered as spontaneous. In contrast, 95 out of 172 (55.2%) colonized isolation sites that were accessible to disinfection procedures were successfully decolonized. Patient compliance with the enforced hygiene procedures was associated with decolonization success. Systemic antibiotic therapy did not relevantly affect isolation time. Disinfecting washing moderately supports local decolonization of multidrug-resistant pathogens in comparison with spontaneous decolonization rates if the patients’ compliance with the applied hygiene procedures is ensured. PMID:28690877

  18. Colonization with Multidrug-Resistant Bacteria - On the Efficiency of Local Decolonization Procedures.

    PubMed

    Münch, Julia; Hagen, Ralf Matthias; Müller, Martin; Kellert, Viktor; Wiemer, Dorothea Franziska; Hinz, Rebecca; Schwarz, Norbert Georg; Frickmann, Hagen

    2017-06-01

    The effectiveness of a disinfectant-based decolonization strategy for multidrug-resistant bacteria like extended spectrum β-lactamase (ESBL)-positive Gram-negative bacteria with or without additional fluoroquinolon and carbapenem resistance as well as vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus was assessed. Between 2011 and 2015, 25 patients from Libya, Syria, and the Ukraine with war traumata were treated at the Bundeswehr hospital Hamburg. The patients were heavily colonized and infected with multidrug-resistant bacteria, altogether comprising 371 distinct combinations of pathogens and isolation sites. Local disinfection was assessed for effectiveness regarding successful decolonization of multidrug-resistant bacteria. Altogether, 170 cases of successful decolonization were observed, comprising 95 (55.8%) such events at sampling sites that were accessible to disinfecting procedures. The remaining 75 (44.2%) decolonization events had to be considered as spontaneous. In contrast, 95 out of 172 (55.2%) colonized isolation sites that were accessible to disinfection procedures were successfully decolonized. Patient compliance with the enforced hygiene procedures was associated with decolonization success. Systemic antibiotic therapy did not relevantly affect isolation time. Disinfecting washing moderately supports local decolonization of multidrug-resistant pathogens in comparison with spontaneous decolonization rates if the patients' compliance with the applied hygiene procedures is ensured.

  19. Activity and selectivity of histidine-containing lytic peptides to antibiotic-resistant bacteria.

    PubMed

    Kharidia, Riddhi; Tu, Zhigang; Chen, Long; Liang, Jun F

    2012-09-01

    Lytic peptides are a group of membrane-acting peptides that are active to antibiotic-resistant bacteria but demonstrate high toxicity to tissue cells. Here, we reported the construction of new lytic peptide derivatives through the replacement of corresponding lysine/arginine residues in lytic peptide templates with histidines. Resulting lytic peptides had the same lethality to antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus, but showed greatly improved selectivity to bacteria. When incubated with co-cultured bacteria and tissue cells, these histidine-containing lytic peptide derivatives killed bacteria selectively but spared co-cultured human cells. Membrane insertion and peptide-quenching studies revealed that histidine protonation controlled peptide interactions with cell membranes determined the bacterial selectivity of lytic peptide derivatives. Compared with parent peptides, lytic peptide derivatives bound to bacteria strongly and inserted deeply into the bacterial cell membrane. Therefore, histidine-containing lytic peptides represent a new group of antimicrobial peptides for bacterial infections in which the antibiotic resistance has developed.

  20. Screening, characterization and biofilm formation of nickel resistant bacteria isolated from indigenous environment.

    PubMed

    Wadood, Hafiz Z; Sabri, Anjum N

    2013-01-01

    Nickel resistant bacteria (ZB, ZC, ZD, ZL, ZK and S1X) were isolated from industrial effluents and corroded iron pieces from indigenous environment of Punjab, Pakistan. These six strains could tolerate nickel at different levels with ZB, ZC, ZD, ZL, ZK, and S1X having 233, 225, 267, 233, 228 and 296 mM minimum inhibitory concentration (MIC) of nickel ions, respectively. These bacteria were sensitive to Cu(+2), Cr(+3), Co(+2), and Al(+3) as they did not grow even in the presence of 1 mM concentration of all these ions in minimal medium, whereas all of them were resistant to Fe3 upto 1.3 mM in minimal medium. The best appropriate temperature for nickel resistant bacteria was 37 degrees C and all of them showed maximum growth at pH 8. These bacteria were characterized morphologically and biochemically. Biofilm forming ability of the bacteria was checked with and without nickel stress and it was found that strains ZK and S1X were able to form a compact biofilm even under nickel stress. The sequencing of 16S rRNA-encoding genes from these nickel resistant bacteria showed that they belonged to four different genera namely, Klebsiella, Pseudomonas, Bacillus and Cronobacter.

  1. Identification and antibacterial resistance of bacteria isolated from poultry.

    PubMed

    El-Rami, Fadi E; Sleiman, Fawwak T; Abdelnoor, Alexander M

    2012-01-01

    Food-borne infections are among the prominent health hazards. Antibacterial agents (ABA) are usually administered to poultry in Lebanon as antibiotic growth promoters (AGP), which might lead to the dissemination of resistant bacterial strains. The aims of this study were to isolate potential food borne pathogens from poultry and investigate an association between AGP usage and antibacterial resistance (ABR). Isolates were obtained from the culture of cloacae swabs and identified. Escherichia coli was the predominant isolate. There was a significant association between the use of tetracycline and gentamicin as AGP and the number of E. coli isolates resistant to these ABA.

  2. Emergence of antibiotic-resistant bacteria in patients with Fournier gangrene.

    PubMed

    Lin, Wei-Ting; Chao, Chien-Ming; Lin, Hsin-Lan; Hung, Ming-Chran; Lai, Chih-Cheng

    2015-04-01

    This study was conducted to investigate the bacteriology and associated patterns of antibiotic resistance Fournier gangrene. Patients with Fournier's gangrene from 2008 to 2012 were identified from the computerized database in a medical center in southern Taiwan. The medical records of all patients with Fournier's gangrene were reviewed retrospectively. There were 61 microorganisms, including 60 bacteria and one Candida spp, isolated from clinical wound specimens from 32 patients. The most common isolates obtained were Streptococcus spp. (n=12), Peptoniphilus spp. (n=8), Staphylococcus aureus (n=7), Escherichia coli (n=7), and Klebsiella pneumoniae (n=7). Among 21 strains of gram-negative bacilli, five (23.8%) were resistant to fluoroquinolones, and three isolates were resistant to ceftriaxone. Two E. coli strains produced extended-spectrum beta-lactamase. Four of the seven S. aureus isolates were methicillin-resistant. Among 15 anaerobic isolates, nine (60%) were resistant to penicillin, and eight (53.3%) were resistant to clindamycin. Four (26.7%) isolates were resistant to metronidazole. The only independent risk factor associated with mortality was inappropriate initial antibiotic treatment (p=0.021). Antibiotic-resistant bacteria are emerging in the clinical setting of Fournier gangrene. Clinicians should use broad-spectrum antibiotics initially to cover possible antibiotic-resistant bacteria.

  3. Frequency and antimicrobial resistance of bacteria isolated from oral and topical medicaments from Hilla, Iraq.

    PubMed

    Al-Charrakh, Alaa H

    2012-06-15

    The presence of microorganisms in pharmaceuticals is undesirable because they may cause spoilage of the product and may present an infection hazard to the consumers or patients. A total of 102 samples of oral and topical non-sterile pharmaceutical products were collected at random from different drug houses and pharmacies in Iraq, to investigate the microbial contamination of these products. Bacterial isolates recovered from these medicaments were subjected to susceptibility testing against various antibiotics by disk diffusion method according to Clinical and Laboratory Standards (CLSI) guidelines. The results revealed that the occurrence of gram-positive bacteria was in oral and topical medicaments while gram-negative bacteria were only detected in topical medicaments. More than 58% of Bacillus isolates were resistant to lincomycin and Bacillus mycoides isolates were resistant to beta-lactam antibiotics and trimethoprim-sulfamethoxazole. Staphylococcus spp. showed a relatively high resistance to ampicillin, amoxicillin, penicillin, tetracycline, and trimethoprim-sulfamethoxazole. S. epidermidis had the highest number of multi-resistant isolates. Furthermore, 87.5% of isolated gram-negative rods showed high resistance to beta-lactam antibiotics and 75% of them were highly resistant to erythromycin. One isolate of Pseudomonas aeruginosa was the most resistant among all gram-negative rod isolates. The high rate of resistance to antimicrobial agents of bacterial isolates recovered from oral and topical medicaments in this study may indicate a widespread antibiotic resistance among bacteria isolated from different sources, including those of anthropological and environmental origin.

  4. ANTIMICROBIAL RESISTANCE AMONG ENTERIC BACTERIA ISOLATED FROM HUMAN AND ANIMAL WASTES AND IMPACTED SURFACE WATERS: COMPARISON WITH NARMS FINDINGS

    EPA Science Inventory

    Human infection with bacteria exhibiting mono or multiple antimicrobial resistance (MAR) has been a growing problem in the US, and studies have implicated livestock as a source of MAR bacteria primarily through foodborne transmission routes. However, waterborne transmission of...

  5. ANTIMICROBIAL RESISTANCE AMONG ENTERIC BACTERIA ISOLATED FROM HUMAN AND ANIMAL WASTES AND IMPACTED SURFACE WATERS: COMPARISON WITH NARMS FINDINGS

    EPA Science Inventory

    Human infection with bacteria exhibiting mono or multiple antimicrobial resistance (MAR) has been a growing problem in the US, and studies have implicated livestock as a source of MAR bacteria primarily through foodborne transmission routes. However, waterborne transmission of...

  6. Assessment of Antibiotic Resistant Commensal Bacteria in Food

    DTIC Science & Technology

    2006-01-01

    Campylobacter jejuni in the absence of antibiotic selection pressure. Proc Natl Acad Sci USA 102: 541–546. 12. Nandi, S., J.J. Maurer, C. Hofacre...Michel, L., and Zhang, Q. (2005) Enhanced in vivo fitness of fluoroquinolone-resistant Campylobacter jejuni in the absence of antibiotic selection...S. Pereira, O. Shin, J. Lin, S. Huang, L. Michel, and Q. Zhang. 2005a. Enhanced in vivo fitness of fluoroquinolone-resistant Campylobacter jejuni

  7. Zinc and copper in animal feed – development of resistance and co-resistance to antimicrobial agents in bacteria of animal origin

    PubMed Central

    Yazdankhah, Siamak; Rudi, Knut; Bernhoft, Aksel

    2014-01-01

    Farmed animals such as pig and poultry receive additional Zn and Cu in their diets due to supplementing elements in compound feed as well as medical remedies. Enteral bacteria in farmed animals are shown to develop resistance to trace elements such as Zn and Cu. Resistance to Zn is often linked with resistance to methicillin in staphylococci, and Zn supplementation to animal feed may increase the proportion of multiresistant E. coli in the gut. Resistance to Cu in bacteria, in particular enterococci, is often associated with resistance to antimicrobial drugs like macrolides and glycopeptides (e.g. vancomycin). Such resistant bacteria may be transferred from the food-producing animals to humans (farmers, veterinarians, and consumers). Data on dose-response relation for Zn/Cu exposure and resistance are lacking; however, it seems more likely that a resistance-driven effect occurs at high trace element exposure than at more basal exposure levels. There is also lack of data which could demonstrate whether Zn/Cu-resistant bacteria may acquire antibiotic resistance genes/become antibiotics resistant, or if antibiotics-resistant bacteria are more capable to become Zn/Cu resistant than antibiotics-susceptible bacteria. Further research is needed to elucidate the link between Zn/Cu and antibiotic resistance in bacteria. PMID:25317117

  8. Emerging antibiotic resistance in bacteria with special reference to India.

    PubMed

    Raghunath, D

    2008-11-01

    The antibiotic era started in the 1940s and changed the profile of infectious diseases and human demography. The burgeoning classes and numbers promised much and elimination of this major cause of human (and animal) morbidity appeared possible. Bacterial antibiotic resistance which was observed soon after antibiotic introduction has been studied extensively. Diverse mechanisms have been demonstrated and the genetic basis elucidated. The resilience of the prokaryote ecosystems to antibiotic stress has been realized. The paper presents these subjects briefly to afford an overview. The epidemiology of antibiotic resistance is dealt with and community practices in different countries are described. The role of high antibiotic usage environments is indicated. The implication of the wide use of antibiotics in animals has been pointed out. Steadily increasing antibiotic resistance and decreasing numbers of newer antibiotics appear to point to a post-antibiotic period during which treatment of infections would become increasingly difficult. This article attempts to review the global antimicrobial resistance scene and juxtaposes it to the Indian experience. The prevalence in India of antibiotic resistance among major groups of pathogens is described. The factors that determine the prevalent high antibiotic resistance rates have been highlighted. The future research activity to ensure continued utility of antibiotics in the control of infections has been indicated.

  9. [Fosfomycin--its significance for treatment of diseases due to multidrug-resistant bacteria].

    PubMed

    Stock, Ingo

    2015-01-01

    Fosfomycin is a bactericidal phosphonic acid derivative, which engages by inhibiting pyruvyltransferase at an early stage in the peptidoglycan synthesis. It shows a broad spectrum of activity that includes many multidrug-resistant gram-negative and gram-positive bacteria. Fosfomycin is active against most strains of Pseudomonas aeruginosa and several multidrug-resistant Enterobacteriaceae, e.g., Escherichia coli strains expressing extended spectrum beta-lactamases (ESBL) and Klebsiella pneumoniae strains with decreased susceptibilities to carbapenems. Most methicillin-resistant Staphylococcus aureus (MRSA) strains as well as enterococci with and without vancomycin resistance are also sensitive to fosfomycin. During the last decade, a variety of studies showed that fosfomycin is not only suitable for treating uncomplicated urinary tract diseases, but also for the treatment of many other diseases caused by bacterial pathogens with and without multidrug resistance. However, large controlled studies demonstrating the efficacy of the drug to treat diseases caused by multidrug-resistant bacteria are still missing. Considering the low number of antibacterial agents with good activity against multidrug-resistant bacteria, fosfomycin should be evaluated as an important antibiotic for the treatment of several severe illnesses due to these pathogens. However, because some multidrug-resistant bacteria are also resistant to fosfomycin, this agent should only be applied if the pathogen is sensitive to this drug. In addition, because rapid development of resistance cannot be excluded if fosfomycin will be applied alone, this drug should only be given in combination with other effective drugs for the treatment of serious systemic diseases due to multidrug-resistant bacterial pathogens.

  10. Detection of heavy metal resistance bioluminescence bacteria using microplate bioassay method.

    PubMed

    Ranjitha, P; Karthy, E S

    2012-01-01

    Effects of different heavy metals on Vibrio harveyi, V. fischeri, Photobacterium phosphoreum and P. leiognathi were examined. Checkerboard assay was used for the detection of the natural metal tolerance levels of a large number of marine luminous eubacteria. 57 strains of luminous bacteria were investigated for their natural patterns of heavy metal tolerance. The behaviors of these strains were not homogeneous with respect to all metals tested, even within the strains belonging to the same genus. At least 1 to 4 different MICs were detected for every metal except barium and cobalt. Isolated bacteria were tested for the presence of plasmids using the modified alkaline lysis method, was effective for identification of plasmids of different sizes. This study revealed the frequency of the occurrence of plasmids in heavy metal resistance bacteria and inferred that plasmids are highly ubiquitous and predominant in most heavy metal resistant bacteria.

  11. Bacteriocins active against multi-resistant gram negative bacteria implicated in nosocomial infections.

    PubMed

    Ghodhbane, Hanen; Elaidi, Sabrine; Sabatier, Jean-Marc; Achour, Sami; Benhmida, Jeannette; Regaya, Imed

    2015-01-01

    Multiresistant Gram-negative bacteria are the prime mover of nosocomial infections. Some are naturally resistant to antibiotics, their genetic makes them insensitive to certain families of antibiotics and they transmit these resistors to their offspring. Moreover, when bacteria are subjected to antibiotics, they eventually develop resistance against drugs to which they were previously sensitive. In recent years, many bacteriocins active against gram-negative bacteria have been identified proving their efficacy in treating infections. While further investigation remains necessary before the possibilities for bacteriocins in clinical practice can be described more fully, this review provides an overview of bacteriocins acting on the most common infectious gram negative bacteria (Klebsiella, Acinetobacter, Pseudomonas aeruginosa and E. coli).

  12. Molecular Characterization of Resistance-Nodulation-Division Transporters from Solvent- and Drug-Resistant Bacteria in Petroleum-Contaminated Soil

    PubMed Central

    Meguro, Norika; Kodama, Yumiko; Gallegos, Maria-Trinidad; Watanabe, Kazuya

    2005-01-01

    PCR assays for analyzing resistance-nodulation-division transporters from solvent- and drug-resistant bacteria in soil were developed. Sequence analysis of amplicons showed that the PCR successfully retrieved transporter gene fragments from soil. Most of the genes retrieved from petroleum-contaminated soils formed a cluster (cluster PCS) that was distantly related to known transporter genes. Competitive PCR showed that the abundance of PCS genes is increased in petroleum-contaminated soil. PMID:15640241

  13. Transfer of plasmid-mediated resistance to tetracycline in pathogenic bacteria from fish and aquaculture environments.

    PubMed

    Guglielmetti, Elena; Korhonen, Jenni M; Heikkinen, Jouni; Morelli, Lorenzo; von Wright, Atte

    2009-04-01

    The transferability of a large plasmid that harbors a tetracycline resistance gene tet(S), to fish and human pathogens was assessed using electrotransformation and conjugation. The plasmid, originally isolated from fish intestinal Lactococcus lactis ssp. lactis KYA-7, has potent antagonistic activity against the selected recipients (Lactococcus garvieae and Listeria monocytogenes), preventing conjugation. Therefore the tetracycline resistance determinant was transferred via electroporation to L. garvieae. A transformant clone was used as the donor in conjugation experiments with three different L. monocytogenes strains. To our knowledge, this is the first study showing the transfer of an antibiotic resistance plasmid from fish-associated lactic bacteria to L. monocytogenes, even if the donor L. garvieae was not the original host of the tetracycline resistance but experimentally created by electroporation. These results demonstrate that the antibiotic resistance genes in the fish intestinal bacteria have the potential to spread both to fish and human pathogens, posing a risk to aquaculture and consumer safety.

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

    PubMed

    Hawkey, P M

    2015-04-01

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

  15. [Common antimicrobial-resistant bacteria in nosocomial infections in Taiwan and their prevention].

    PubMed

    Lin, Nien-Tsung

    2011-08-01

    Infections caused by antibiotic-resistant bacteria, especially multidrug-resistant strains (MDR) that cause difficulties in clinical treatment, have long been a problem of global concern. Drug-resistant strains of common nosocomial infections in Taiwan include Gram-positive coccal methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci, and Gram-negative bacilli such as carbapenem-resistant Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae, among others. About 10 to 20% of Gram-negative bacteria that encode extended-spectrum β-lactamases are resistant to cephalosporin, a third generation antibiotic, and the fluoroquinolone-resistance rate has continued to increase in recent years. Despite the high mortality rate in patients with infections caused by MDR, the problem is still solvable by blocking or reducing MDR dissemination in addition to proper antibiotics use. Hand hygiene is the simplest, most effective measure for preventing nosocomial infections. However, healthcare workers' adherence to recommended hand hygiene practices is unacceptably low worldwide, making the promotion of hand hygiene a major challenge for infection control experts. Therefore, as a first step of preventing the spread of MDR bacteria, knowledge of hand hygiene and adherence to hand hygiene practices must be required of healthcare workers. Such should help reduce nosocomial infections significantly and upgrade healthcare quality.

  16. Prevalence and diversity of carbapenem-resistant bacteria in untreated drinking water in Portugal.

    PubMed

    Henriques, Isabel S; Araújo, Susana; Azevedo, Juliana S N; Alves, Marta Salgueiro; Chouchani, Chedly; Pereira, Anabela; Correia, António

    2012-10-01

    We examined the prevalence and diversity of carbapenem-resistant bacteria (CRB) in untreated drinking water. Prevalence was estimated in plate count agar (PCA) and R2A media with or without antibiotics. Clonal relatedness of isolates was established by repetitive extragenic palindroitic (REP)-PCR. Phylogeny was based on the 16S rRNA gene. Antimicrobial susceptibility was assessed by disc diffusion methods. Genes encoding beta-lactamases and integrases were inspected by PCR. CRB ranged from 0.02% to 15.9% of cultivable bacteria, while ampicillin-resistant bacteria ranged from 1.5% to 31.4%. Carbapenem-resistant isolates affiliated with genera Stenotrophomonas, Pseudomonas, Janthinobacterium, Chryseobacterium, Sphingobacterium, Acidovorax, Caulobacter, Cupriavidus, and Sphingomonas. CRB were highly resistant to beta-lactams, but mostly susceptible to other classes. Transmissible beta-lactamase genes and integrase genes were not detected. The genus-specific bla(L1) was detected in 61% of the Stenotrophomonas isolates. Contrarily to what has been reported for extensively used antibiotics, low levels of carbapenem resistance were detected in untreated drinking water, often represented by intrinsically resistant genera. Production of chromosomal-encoded carbapenemases was the prevalent carbapenem resistance mechanism. Results suggest that the dissemination of anthropogenic-derived carbapenem resistance is at an early stage. This presents an opportunity to rationally develop monitoring strategies to identify dissemination routes and assess the impact of human actions in the environmental resistome.

  17. Co-occurrence of resistance to different antibiotics among aquatic bacteria.

    PubMed

    Voolaid, Veiko; Jõers, Arvi; Kisand, Veljo; Tenson, Tanel

    2012-10-02

    Antibiotic resistance is not confined to pathogens, but is also widespread in various natural environments. In nature the microbes producing antibiotic compounds have been around for millions of years. Heavy use of antibiotics in medicine and veterinary practice may lead to the accumulation of resistance genes in microbial populations, followed by a rise in multiresistant bacteria. To test the extent of resistance among aquatic bacteria, we have collected 760 isolates resistant to at least one antibiotic. The phylogeny of the isolates covers a wide range of Proteobacteria, Actinobacteria and Bacteroidetes. In order to determine the extent of multiresistance, the isolates were tested on six antibiotics. As the growth rate of the different bacteria was highly variable, the classical medical resistance tests could not be used, and an alternative method considering the full growth curve was developed. In general, the overall resistances to different antibiotics could be explained by random, independent distribution. An exception to this was the resistances against tetracycline and chloramphenicol, which tended to occur in pairs. We conclude that there is no massive spread of multiresistance determinants in the studied environment, although some specific cases can be found, awaiting for molecular characterization of the resistance mechanisms.

  18. Molecular analysis of antimicrobial resistance in gram-negative bacteria isolated from fish farms in Egypt.

    PubMed

    Ishida, Yojiro; Ahmed, Ashraf M; Mahfouz, Nadia B; Kimura, Tomomi; El-Khodery, Sabry A; Moawad, Amgad A; Shimamoto, Tadashi

    2010-06-01

    As little is known about antimicrobial resistance genes in fish farms, this study was conducted to monitor the incidence and prevalence of a wide range of antimicrobial resistance genes in Gram-negative bacteria isolated from water samples taken from fish farms in the northern part of Egypt. Ninety-one out of two hundred seventy-four (33.2%) non-repetitive isolates of Gram-negative bacteria showed multidrug resistance phenotypes and harbored at least one antimicrobial resistance gene. PCR and DNA sequencing results showed that 72 (26.3%) isolates contain tetracycline resistance genes and 19 (6.9%) isolates were positive for class 1 integrons with 12 different gene cassettes. The beta-lactamase-encoding genes were identified in 14 (5.1%) isolates. The plasmid-mediated quinolone resistance genes, qnr and aac(6')-Ib-cr, were identified in 16 (5.8%) and 3 (1.1%) isolates, respectively. Finally, the florphenicol resistance gene, floR, was identified in four (1.5%) isolates. To the best of our knowledge, this is the first report for molecular characterization of antimicrobial resistance in Gram-negative bacteria isolated from fish farms in Africa.

  19. Examination of bacteria drug resistance utilizing surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Chiang, Ya-Ling; Chen, How-Foo; Lin, Chi-Hung; Chen, Shean-Jen

    2007-05-01

    An antimicrobial testing method using surface plasmon resonance to improve the present techniques is reported in this paper. Different from conventional methods, namely Kirby-Bauer disk diffusion and variations of broth microdilution, the examination time is reduced from 18-24 hours or more to less than one hour after the treatment of antibiotics. E-coli resistant and susceptible to ampicillin are used in the test to demonstrate this innovative method. It is generally known that discovering a method to exam the bacterium resistance rapidly and correctly is very important for patients and for preventing infective disease from spreading. The method reported can benefit this requirement.

  20. Laser thermal ablation of multidrug-resistant bacteria using functionalized gold nanoparticles

    PubMed Central

    Mocan, Lucian; Tabaran, Flaviu A; Mocan, Teodora; Pop, Teodora; Mosteanu, Ofelia; Agoston-Coldea, Lucia; Matea, Cristian T; Gonciar, Diana; Zdrehus, Claudiu; Iancu, Cornel

    2017-01-01

    The issue of multidrug resistance (MDR) has become an increasing threat to public health. One alternative strategy against MDR bacteria would be to construct therapeutic vectors capable of physically damaging these microorganisms. Gold nanoparticles hold great promise for the development of such therapeutic agents, since the nanoparticles exhibit impressive properties, of which the most important is the ability to convert light into heat. This property has scientific significance since is exploited to develop nano-photothermal vectors to destroy bacteria at a molecular level. The present paper summarizes the latest advancements in the field of nanotargeted laser hyperthermia of MDR bacteria mediated by gold nanoparticles. PMID:28356741

  1. Multidrug-resistant Gram-negative bacteria in solid organ transplant recipients with bacteremias.

    PubMed

    Wan, Q Q; Ye, Q F; Yuan, H

    2015-03-01

    Bloodstream infections (BSIs) remain as life-threatening complications and are associated with significant morbidity and mortality among solid organ transplant (SOT) recipients. Multidrug-resistant (MDR) Gram-negative bacteria can cause serious bacteremias in these recipients. Reviews have aimed to investigate MDR Gram-negative bacteremias; however, they were lacking in SOT recipients in the past. To better understand the characteristics of bacteremias due to MDR Gram-negative bacteria, optimize preventive and therapeutic strategies, and improve the outcomes of SOT recipients, this review summarize the epidemiology, clinical and laboratory characteristics, and explores the mechanisms, prevention, and treatment of MDR Gram-negative bacteria.

  2. Colonization of Libyan civil war casualties with multidrug-resistant bacteria.

    PubMed

    Koole, K; Ellerbroek, P M; Lagendijk, R; Leenen, L P H; Ekkelenkamp, M B

    2013-07-01

    In November 2011 51 Libyan war casualties were admitted to the Major Incident Hospital in Utrecht and from there were transferred to 26 other Dutch hospitals. Cultures and clinical data were collected to establish the prevalence of multidrug-resistant (MDR) bacteria in this patient group and to identify the associated risk factors. The prevalence of MDR bacteria was 59% (30/51 patients); extended spectrum β-lactamase-producing enterobacteriaceae were most common (26/51 patients: 51%). The major risk factor for carriage of MDR bacteria was the presence of open wounds at admission to the Major Incident Hospital.

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

    PubMed

    Ito, Ryota; Mustapha, Mustapha M; Tomich, Adam D; Callaghan, Jake D; McElheny, Christi L; Mettus, Roberta T; Shanks, Robert M Q; Sluis-Cremer, Nicolas; Doi, Yohei

    2017-08-29

    Fosfomycin is a decades-old antibiotic which is being revisited because of its perceived activity against many extensively drug-resistant Gram-negative pathogens. FosA proteins are Mn(2+) and K(+)-dependent glutathione S-transferases which confer fosfomycin resistance in Gram-negative bacteria by conjugation of glutathione to the antibiotic. Plasmid-borne fosA variants have been reported in fosfomycin-resistant Escherichia coli strains. However, the prevalence and distribution of fosA in other Gram-negative bacteria are not known. We systematically surveyed the presence of fosA in Gram-negative bacteria in over 18,000 published genomes from 18 Gram-negative species and investigated their contribution to fosfomycin resistance. We show that FosA homologues are present in the majority of genomes in some species (e.g., Klebsiella spp., Enterobacter spp., Serratia marcescens, and Pseudomonas aeruginosa), whereas they are largely absent in others (e.g., E. coli, Acinetobacter baumannii, and Burkholderia cepacia). FosA proteins in different bacterial pathogens are highly divergent, but key amino acid residues in the active site are conserved. Chromosomal fosA genes conferred high-level fosfomycin resistance when expressed in E. coli, and deletion of chromosomal fosA in S. marcescens eliminated fosfomycin resistance. Our results indicate that FosA is encoded by clinically relevant Gram-negative species and contributes to intrinsic fosfomycin resistance.IMPORTANCE There is a critical need to identify alternate approaches to treat infections caused by extensively drug-resistant (XDR) Gram-negative bacteria. Fosfomycin is an old antibiotic which is routinely used for the treatment of urinary tract infections, although there is substantial interest in expanding its use to systemic infections caused by XDR Gram-negative bacteria. In this study, we show that fosA genes, which encode dimeric Mn(2+)- and K(+)-dependent glutathione S-transferase, are widely distributed in the

  4. Antibiotic Resistant Bacteria--What Everyone Needs To Know.

    ERIC Educational Resources Information Center

    Pascoe, Neil; Felkner, Marilyn; Maldonado, Maria

    2003-01-01

    Notes the overuse of antibiotics and the resulting resistant bacterial strains. Describes how to control and prevent staphylococcal infections specifically, and almost all infectious diseases generally. Specific sections address: (1) what are staph infections; (2) preventing staph infections; (3) caring for wounds; and (4) controlling staph…

  5. Photoexcited quantum dots for killing multidrug-resistant bacteria

    NASA Astrophysics Data System (ADS)

    Courtney, Colleen M.; Goodman, Samuel M.; McDaniel, Jessica A.; Madinger, Nancy E.; Chatterjee, Anushree; Nagpal, Prashant

    2016-05-01

    Multidrug-resistant bacterial infections are an ever-growing threat because of the shrinking arsenal of efficacious antibiotics. Metal nanoparticles can induce cell death, yet the toxicity effect is typically nonspecific. Here, we show that photoexcited quantum dots (QDs) can kill a wide range of multidrug-resistant bacterial clinical isolates, including methicillin-resistant Staphylococcus aureus, carbapenem-resistant Escherichia coli, and extended-spectrum β-lactamase-producing Klebsiella pneumoniae and Salmonella typhimurium. The killing effect is independent of material and controlled by the redox potentials of the photogenerated charge carriers, which selectively alter the cellular redox state. We also show that the QDs can be tailored to kill 92% of bacterial cells in a monoculture, and in a co-culture of E. coli and HEK 293T cells, while leaving the mammalian cells intact, or to increase bacterial proliferation. Photoexcited QDs could be used in the study of the effect of redox states on living systems, and lead to clinical phototherapy for the treatment of infections.

  6. Antibiotic Resistant Bacteria--What Everyone Needs To Know.

    ERIC Educational Resources Information Center

    Pascoe, Neil; Felkner, Marilyn; Maldonado, Maria

    2003-01-01

    Notes the overuse of antibiotics and the resulting resistant bacterial strains. Describes how to control and prevent staphylococcal infections specifically, and almost all infectious diseases generally. Specific sections address: (1) what are staph infections; (2) preventing staph infections; (3) caring for wounds; and (4) controlling staph…

  7. Photoexcited quantum dots for killing multidrug-resistant bacteria.

    PubMed

    Courtney, Colleen M; Goodman, Samuel M; McDaniel, Jessica A; Madinger, Nancy E; Chatterjee, Anushree; Nagpal, Prashant

    2016-05-01

    Multidrug-resistant bacterial infections are an ever-growing threat because of the shrinking arsenal of efficacious antibiotics. Metal nanoparticles can induce cell death, yet the toxicity effect is typically nonspecific. Here, we show that photoexcited quantum dots (QDs) can kill a wide range of multidrug-resistant bacterial clinical isolates, including methicillin-resistant Staphylococcus aureus, carbapenem-resistant Escherichia coli, and extended-spectrum β-lactamase-producing Klebsiella pneumoniae and Salmonella typhimurium. The killing effect is independent of material and controlled by the redox potentials of the photogenerated charge carriers, which selectively alter the cellular redox state. We also show that the QDs can be tailored to kill 92% of bacterial cells in a monoculture, and in a co-culture of E. coli and HEK 293T cells, while leaving the mammalian cells intact, or to increase bacterial proliferation. Photoexcited QDs could be used in the study of the effect of redox states on living systems, and lead to clinical phototherapy for the treatment of infections.

  8. Evaluation of antimicrobial resistance of bovine bacteria to antibiotics

    USDA-ARS?s Scientific Manuscript database

    Antimicrobial resistance (AMR) is one of the most formidable threats to human medicine today. Therefore, the research objective is to evaluate the susceptibility of Staphylococcus species isolated from beef cows to 12 antibiotics commonly used in treating human and animal infections. This research w...

  9. Functional gold nanoclusters as antimicrobial agents for antibiotic-resistant bacteria.

    PubMed

    Chen, Wei-Yu; Lin, Ju-Yu; Chen, Wei-Jen; Luo, Liyang; Wei-Guang Diau, Eric; Chen, Yu-Chie

    2010-07-01

    Our aim was to demonstrate that lysozyme-directed generation of gold nanoclusters (Au NCs) are potential antimicrobial agents for antibiotic-resistant bacteria and broad labeling agents for pathogenic bacteria. Lysozyme is an enzyme that is capable of hydrolyzing the cell walls of bacteria. In this study, we demonstrated the generation of functional Au NCs by using lysozyme as the sequester and the reducing agent for Au precursors at 40 degrees C. In addition, to shorten the reaction time, the reaction was conducted under microwave irradiation within a short period of time for the first time. The bioactivity of the lysozyme on the Au NCs was retained. Therefore, the as-prepared lysozyme-Au NCs with desirable fluorescence feature were successfully employed to be broad-band labeling agents for pathogenic bacteria. Furthermore, we also demonstrated that the lysozyme-Au NCs can be used to effectively inhibit the cell growth of notorious antibiotic-resistant bacteria, including pan-drug-resistant Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis. The potential of employing the lysozyme-Au NCs for bacterial labeling and as antimicrobial agents is expected.

  10. Vapour-phase activities of essential oils against antibiotic sensitive and resistant bacteria including MRSA.

    PubMed

    Doran, A L; Morden, W E; Dunn, K; Edwards-Jones, V

    2009-04-01

    To determine whether essential oil (EO) vapours could reduce surface and airborne levels of bacteria including methicillin-resistant Staphylococcus aureus (MRSA). The antibacterial activity of geranium and lemongrass EO individually and blended were evaluated over a range of concentrations by direct contact and vapour diffusion. The EO were tested in vitro against a selection of antibiotic-sensitive and -resistant bacteria, including MRSA, vancomycin-resistant Enterococci (VRE), Acinetobacter baumanii and Clostridium difficile. An EO blend containing lemongrass and geranium was used to formulate BioScent that was dispersed into the environment using the ST Pro machine. The effects were variable depending on the methods used. In a sealed box environment, MRSA growth on seeded plates was reduced by 38% after 20 h exposure to BioScent vapour. In an office environment, the ST Pro machine dispersing BioScent effected an 89% reduction of airborne bacteria in 15 h, when operated at a constant output of 100%. EO vapours inhibited growth of antibiotic-sensitive and -resistant bacteria in vitro and reduced surface and airborne levels of bacteria. Results suggest that EO vapours, particularly Bioscent, could be used as a method of air disinfection.

  11. Effect of in-feed paromomycin supplementation on antimicrobial resistance of enteric bacteria in turkeys.

    PubMed

    Kempf, Isabelle; Le Roux, Aurélie; Perrin-Guyomard, Agnès; Mourand, Gwenaëlle; Le Devendec, Laetitia; Bougeard, Stéphanie; Richez, Pascal; Le Pottier, Gilles; Eterradossi, Nicolas

    2013-11-01

    Histomoniasis in turkeys can be prevented by administering paromomycin sulfate, an aminoglycoside antimicrobial agent, in feed. The aim of this study was to evaluate the impact of in-feed paromomycin sulfate supplementation on the antimicrobial resistance of intestinal bacteria in turkeys. Twelve flocks of breeder turkeys were administered 100 ppm paromomycin sulfate from hatching to day 120; 12 flocks not supplemented with paromomycin were used as controls. Faecal samples were collected monthly from days 0 to 180. The resistance of Escherichia coli, Enterococcus faecium and Staphylococcus aureus to paramomycin and other antimicrobial agents was compared in paromomycin supplemented (PS) and unsupplemented (PNS) flocks. E. coli from PS birds had a significantly higher frequency of resistance to paromomycin, neomycin and kanamycin until 1 month after the end of supplementation compared to PNS birds. Resistance to amoxicillin or trimethoprim-sulfamethoxazole was also more frequent in PS turkeys. Resistance was mainly due to the presence of aph genes, which could be transmitted by conjugation, sometimes with streptomycin, tetracycline, amoxicillin, trimethoprim or sulfonamide resistance genes. Resistance to kanamycin and streptomycin in E. faecium was significantly different in PS and PNS breeders on days 60 and 90. Significantly higher frequencies of resistance to paromomycin, kanamycin, neomycin and tobramycin were observed in S. aureus isolates from PS birds. Paromomycin supplementation resulted in resistance to aminoglycosides in bacteria of PS turkeys. Co-selection for resistance to other antimicrobial agents was observed in E. coli isolates. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Antimicrobial resistance of gram-negative bacteria isolated from foods in Mexico.

    PubMed

    Wood, L V; Morgan, D R; DuPont, H L

    1983-10-01

    When trimethoprim-sulfamethoxazole was given to US travelers in Mexico to prevent diarrheal illness, high-level resistance to the drug emerged [2], although in previous studies such resistance had not been observed among enteric flora following administration of trimethoprim-sulfamethoxazole as prophylaxis against urinary tract infection [3]. Since food has been shown to be an important vehicle of transmission of travelers' diarrhea, food samples were examined for the presence of drug-resistant bacteria to explain the acquisition of high-level resistance among enteric flora of individuals taking antibiotics as prophylaxis against traveler's diarrhea. Of 34 strains of ETEC isolated from US students in Guadalajara, Mexico, who had acute gastroenteritis, one was resistant to trimethoprim and one was resistant to trimethoprim-sulfamethoxazole. Eight of the ETEC strains tested demonstrated multiple drug resistance. Twenty-two of 149 isolates from food produced enterotoxin. Only one isolate, which was nontoxigenic, was resistant to trimethoprim, and no coliforms were resistant to trimethoprim-sulfamethoxazole; however, 16 isolates demonstrated multiple drug resistance. Of 235 gram-negative organisms recovered from frozen food samples grown on antibiotic-containing media and tested for enterotoxin production, no isolates were enterotoxigenic. Thirty-four isolates were resistant to trimethoprim, 15 were resistant to trimethoprim-sulfamethoxazole, and 33 demonstrated multiple resistance. Multiple drug resistance was demonstrated among gram-negative organisms isolated from patients' stools and foods in Mexico.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Exposing Plasmids as the Achilles’ Heel of Drug-Resistant Bacteria

    PubMed Central

    Williams, Julia J.; Hergenrother, Paul J.

    2008-01-01

    Many multi-drug resistant bacterial pathogens harbor large plasmids that encode proteins conferring resistance to antibiotics. While the acquisition of these plasmids often enables bacteria to survive in the presence of antibiotics, it is possible that plasmids also represent a vulnerability that can be exploited in tailored antibacterial therapy. This review highlights three recently described strategies designed to specifically combat bacteria harboring such plasmids: Inhibition of plasmid conjugation, inhibition of plasmid replication, and exploitation of plasmid-encoded toxin-antitoxin systems. PMID:18625335

  14. Cleaning, resistant bacteria, and antibiotic prescribing in residential aged care facilities.

    PubMed

    Cowan, Raquel U; Kishan, Divya; Walton, Aaron L; Sneath, Emmy; Cheah, Thomas; Butwilowsky, Judith; Friedman, N Deborah

    2016-03-01

    Residents of residential aged care facilities (RACFs) are at risk of colonization and infection with multidrug-resistant bacteria, and antibiotic prescribing is often inappropriate and not based on culture-proven infection. We describe low levels of resident colonization and environmental contamination with resistant gram-negative bacteria in RACFs, but high levels of empirical antibiotic use not guided by microbiologic culture. This research highlights the importance of antimicrobial stewardship and environmental cleaning in aged care facilities. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

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

    PubMed Central

    Ito, Ryota; Tomich, Adam D.; Callaghan, Jake D.; McElheny, Christi L.; Mettus, Roberta T.; Sluis-Cremer, Nicolas

    2017-01-01

    ABSTRACT Fosfomycin is a decades-old antibiotic which is being revisited because of its perceived activity against many extensively drug-resistant Gram-negative pathogens. FosA proteins are Mn2+ and K+-dependent glutathione S-transferases which confer fosfomycin resistance in Gram-negative bacteria by conjugation of glutathione to the antibiotic. Plasmid-borne fosA variants have been reported in fosfomycin-resistant Escherichia coli strains. However, the prevalence and distribution of fosA in other Gram-negative bacteria are not known. We systematically surveyed the presence of fosA in Gram-negative bacteria in over 18,000 published genomes from 18 Gram-negative species and investigated their contribution to fosfomycin resistance. We show that FosA homologues are present in the majority of genomes in some species (e.g., Klebsiella spp., Enterobacter spp., Serratia marcescens, and Pseudomonas aeruginosa), whereas they are largely absent in others (e.g., E. coli, Acinetobacter baumannii, and Burkholderia cepacia). FosA proteins in different bacterial pathogens are highly divergent, but key amino acid residues in the active site are conserved. Chromosomal fosA genes conferred high-level fosfomycin resistance when expressed in E. coli, and deletion of chromosomal fosA in S. marcescens eliminated fosfomycin resistance. Our results indicate that FosA is encoded by clinically relevant Gram-negative species and contributes to intrinsic fosfomycin resistance. PMID:28851843

  16. The role of surveillance systems in confronting the global crisis of antibiotic-resistant bacteria.

    PubMed

    Perez, Federico; Villegas, Maria Virginia

    2015-08-01

    It is widely accepted that infection control, advanced diagnostics, and novel therapeutics are crucial to mitigate the impact of antibiotic-resistant bacteria. The role of global, national, and regional surveillance systems as part of the response to the challenge posed by antibiotic resistance is not sufficiently highlighted. We provide an overview of contemporary surveillance programs, with emphasis on gram-negative bacteria. The WHO and public health agencies in Europe and the United States recently published comprehensive surveillance reports. These highlight the emergence and dissemination of carbapenem-resistant Enterobacteriaceae and other multidrug-resistant gram-negative bacteria. In Israel, public health action to control carbapenem-resistant Enterobacteriaceae, especially Klebsiella pneumoniae carbapenemase producing K. pneumoniae, has advanced together with a better understanding of its epidemiology. Surveillance models adapted to the requirements and capacities of each country are in development. Robust surveillance systems are essential to combat antibiotic resistance, and need to emphasize a 'one health' approach. Refinements in surveillance will come from advances in bioinformatics and genomics that permit the integration of global and local information about antibiotic consumption in humans and animals, molecular mechanisms of resistance, and bacterial genotyping.

  17. [Rhizospheria bacteria of Poplus euphratica improve resistance of wood plants to heavy metals].

    PubMed

    Chen, Wen; Ouyang, Li-ming; Kong, Pei-jun; Yang, Ze-yu; Wu, Wei; Zhu, Dong-lin; Zhang, Li-li

    2015-09-01

    Populus euphratica is a special kind of woody plant, which lives in desert area of northwestern China and is strongly resistant to multiple abiotic stresses. However, the knowledge about the ecology and physiological roles of microbes associated with P. euphratica is still not enough. In this paper, we isolated 72 strains resistant to heavy metals from rhizospheric soil of wild P. euphratica forest in Shaya County of Xinjiang. There were 50 strains conveying resistance to one of four heavy metals (Cu2+, Ni2+, Pb2+ or Zn2+), and 9 strains were resistant to at least three kinds of these heavy metals. Five of the multi-heavy metal resistant bacteria were inoculated to bamboo willow and the growth inhibition of plant under stresses of Cu2+ or Zn2+ was found to be alleviated to different extent. Among the 5 strains, Pseudomonas sp. Z30 and Cupriavidus sp. N8 significantly improved the growth of plant under stresses of both zinc and copper when compared to the uninoculated controls. The results showed the diversity of heavy metal resistant bacteria associated with P. euphratica which lived in a non-heavy metal polluted area and some of the multi-heavy metal resistant bacteria may greatly improve the growth of host plant under heavy metal.stress. The PGPB associated with P. euphratica has potential application in the xylophyte-microbe remediation of environmental heavy metal pollution.

  18. Efficacy of surface disinfectant cleaners against emerging highly resistant gram-negative bacteria

    PubMed Central

    2014-01-01

    Background Worldwide, the emergence of multidrug-resistant gram-negative bacteria is a clinical problem. Surface disinfectant cleaners (SDCs) that are effective against these bacteria are needed for use in high risk areas around patients and on multi-touch surfaces. We determined the efficacy of several SDCs against clinically relevant bacterial species with and without common types of multidrug resistance. Methods Bacteria species used were ATCC strains; clinical isolates classified as antibiotic-susceptible; and multi-resistant clinical isolates from Klebsiella oxytoca, Klebsiella pneumoniae, and Serratia marcescens (all OXA-48 and KPC-2); Acinetobacter baumannii (OXA-23); Pseudomonas aeruginosa (VIM-1); and Achromobacter xylosoxidans (ATCC strain). Experiments were carried out according to EN 13727:2012 in quadruplicate under dirty conditions. The five evaluated SDCs were based on alcohol and an amphoteric substance (AAS), an oxygen-releaser (OR), surface-active substances (SAS), or surface-active-substances plus aldehydes (SASA; two formulations). Bactericidal concentrations of SDCs were determined at two different contact times. Efficacy was defined as a log10 ≥ 5 reduction in bacterial cell count. Results SDCs based on AAS, OR, and SAS were effective against all six species irrespective of the degree of multi-resistance. The SASA formulations were effective against the bacteria irrespective of degree of multi-resistance except for one of the four P. aeruginosa isolates (VIM-1). We found no general correlation between SDC efficacy and degree of antibiotic resistance. Conclusions SDCs were generally effective against gram-negative bacteria with and without multidrug resistance. SDCs are therefore suitable for surface disinfection in the immediate proximity of patients. Single bacterial isolates, however, might have reduced susceptibility to selected biocidal agents. PMID:24885029

  19. Recent investigations and updated criteria for the assessment of antibiotic resistance in food lactic acid bacteria.

    PubMed

    Clementi, Francesca; Aquilanti, Lucia

    2011-12-01

    The worldwide use, and misuse, of antibiotics for about sixty years in the so-called antibiotic era, has been estimated in some one to ten million tons, a relevant part of which destined for non-therapeutic purposes such as growth promoting treatments for livestock or crop protection. As highly adaptable organisms, bacteria have reacted to this dramatic change in their environment by developing several well-known mechanisms of antibiotic resistance and are becoming increasingly resistant to conventional antibiotics. In recent years, commensal bacteria have become a cause of concern since they may act as reservoirs for the antibiotic resistance genes found in human pathogens. In particular, the food chain has been considered the main route for the introduction of animal and environment associated antibiotic resistant bacteria into the human gastrointestinal tract (GIT) where these genes may be transferred to pathogenic and opportunistic bacteria. As fundamental microbial communities in a large variety of fermented foods and feed, the anaerobe facultative, aerotolerant lactic acid bacteria (LAB) are likely to play a pivotal role in the resistance gene exchange occurring in the environment, food, feed and animal and human GIT. Therefore their antibiotic resistance features and their genetic basis have recently received increasing attention. The present article summarises the results of the latest studies on the most typical genera belonging to the low G + C branch of LAB. The evolution of the criteria established by European regulatory bodies to ensure a safe use of microorganisms in food and feed, including the assessment of their antibiotic resistance is also reviewed.

  20. Efficacy of surface disinfectant cleaners against emerging highly resistant gram-negative bacteria.

    PubMed

    Reichel, Mirja; Schlicht, Anastasija; Ostermeyer, Christiane; Kampf, Günter

    2014-05-28

    Worldwide, the emergence of multidrug-resistant gram-negative bacteria is a clinical problem. Surface disinfectant cleaners (SDCs) that are effective against these bacteria are needed for use in high risk areas around patients and on multi-touch surfaces. We determined the efficacy of several SDCs against clinically relevant bacterial species with and without common types of multidrug resistance. Bacteria species used were ATCC strains; clinical isolates classified as antibiotic-susceptible; and multi-resistant clinical isolates from Klebsiella oxytoca, Klebsiella pneumoniae, and Serratia marcescens (all OXA-48 and KPC-2); Acinetobacter baumannii (OXA-23); Pseudomonas aeruginosa (VIM-1); and Achromobacter xylosoxidans (ATCC strain). Experiments were carried out according to EN 13727:2012 in quadruplicate under dirty conditions. The five evaluated SDCs were based on alcohol and an amphoteric substance (AAS), an oxygen-releaser (OR), surface-active substances (SAS), or surface-active-substances plus aldehydes (SASA; two formulations). Bactericidal concentrations of SDCs were determined at two different contact times. Efficacy was defined as a log10 ≥ 5 reduction in bacterial cell count. SDCs based on AAS, OR, and SAS were effective against all six species irrespective of the degree of multi-resistance. The SASA formulations were effective against the bacteria irrespective of degree of multi-resistance except for one of the four P. aeruginosa isolates (VIM-1). We found no general correlation between SDC efficacy and degree of antibiotic resistance. SDCs were generally effective against gram-negative bacteria with and without multidrug resistance. SDCs are therefore suitable for surface disinfection in the immediate proximity of patients. Single bacterial isolates, however, might have reduced susceptibility to selected biocidal agents.

  1. Distribution of antibiotic-resistant bacteria in chicken manure and manure-fertilized vegetables.

    PubMed

    Yang, Qingxiang; Ren, Siwei; Niu, Tianqi; Guo, Yuhui; Qi, Shiyue; Han, Xinkuan; Liu, Dong; Pan, Feng

    2014-01-01

    Veterinary manure is an important pollution reservoir of antibiotics and antibiotic-resistant bacteria (ARB). However, little is known of the distribution of ARB in plant endophytic bacteria and the number/types of ARB in chicken manure. In this study, 454-pyrosequencing was used to investigate the distribution and composition of ARBs in chicken manure and fertilized vegetables. The prevalence of ARB in the samples of the chicken manure compost recovered from farms on which amoxicillin, kanamycin, gentamicin, and cephalexin were used was 20.91-65.9% for ARBs and 8.24-20.63% simultaneously resistant to two or more antibiotics (multiple antibiotic resistant bacteria (MARB)). Antibiotic-resistant endophytic bacteria were widely detected in celery, pakchoi, and cucumber with the highest rate of resistance to cephalexin. The pyrosequencing indicated that the chicken manure dominantly harbored Firmicutes, Bacteroidetes, Synergistetes, and Proteobacteria and that Bacteroidetes was significantly enhanced in farms utilizing antibiotics. In the total cultivable colonies, 62.58-89.43% ARBs and 95.29% MARB were clustered in Bacteroidetes with the dominant species (Myroides ordoratimimus and Spningobacterium spp., respectively) related to human clinical opportunistic pathogens.

  2. Amoebae-resisting bacteria in drinking water: risk assessment and management.

    PubMed

    Loret, J F; Jousset, M; Robert, S; Saucedo, G; Ribas, F; Thomas, V; Greub, G

    2008-01-01

    Free-living amoebae have been detected in a large number of man-made water systems, including drinking water distribution systems. Some of these amoebae can host amoebae-resisting bacteria, and thus act potentially as reservoirs and vehicles for a number of pathogens. The objectives of this study were to characterize the amoebae and amoebae-resisting bacteria present in different raw waters used for drinking water production, and to assess the efficiency of different treatments applied for drinking water production in removing or inactivating these amoebae. The preliminary results of this study confirm the presence of amoebae and amoebae-resisting bacteria in raw waters used for drinking water production. Due to their capacity to encyst, most of these amoebae are extremely resistant to disinfection processes. In these conditions, preventing the dissemination of these micro-organisms through drinking water will mainly require their physical removal by clarification and filtration processes. The particular hazard that amoebae-resisting bacteria represent in drinking water production should be taken into account in any risk assessment conducted in the framework of a water safety plan, and control strategies based on physical removal rather than disinfection should be adopted where necessary. (c) IWA Publishing 2008.

  3. Incidence and diversity of antimicrobial multidrug resistance profiles of uropathogenic bacteria.

    PubMed

    Linhares, Inês; Raposo, Teresa; Rodrigues, António; Almeida, Adelaide

    2015-01-01

    The aim of this study was to assess the most frequent multidrug resistant (MDR) profiles of the main bacteria implicated in community-acquired urinary tract infections (UTI). Only the MDR profiles observed in, at least, 5% of the MDR isolates were considered. A quarter of the bacteria were MDR and the most common MDR profile, including resistance to penicillins, quinolones, and sulfonamides (antibiotics with different mechanisms of action, all mainly recommended by the European Association of Urology for empirical therapy of uncomplicated UTI), was observed, alone or in association with resistance to other antimicrobial classes, in the main bacteria implicated in UTI. The penicillin class was included in all the frequent MDR profiles observed in the ten main bacteria and was the antibiotic with the highest prescription during the study period. The sulfonamides class, included in five of the six more frequent MDR profiles, was avoided between 2000 and 2009. The results suggest that the high MDR percentage and the high diversity of MDR profiles result from a high prescription of antibiotics but also from antibiotic-resistant genes transmitted with other resistance determinants on mobile genetic elements and that the UTI standard treatment guidelines must be adjusted for the community of Aveiro District.

  4. Nisin and class IIa bacteriocin resistance among Listeria and other foodborne pathogens and spoilage bacteria.

    PubMed

    Kaur, Gurpreet; Malik, Ravinder Kumar; Mishra, Santosh Kumar; Singh, Tejinder Pal; Bhardwaj, Arun; Singroha, Garima; Vij, Shilpa; Kumar, Naresh

    2011-06-01

    Food safety has been an important issue globally due to increasing foodborne diseases and change in food habits. To inactivate foodborne pathogens, various novel technologies such as biopreservation systems have been studied. Bacteriocins are ribosomally synthesized peptides or proteins with antimicrobial activity produced by different groups of bacteria, but the bacteriocins produced by many lactic acid bacteria offer potential applications in food preservation. The use of bacteriocins in the food industry can help reduce the addition of chemical preservatives as well as the intensity of heat treatments, resulting in foods that are more naturally preserved. However, the development of highly tolerant and/or resistant strains may decrease the efficiency of bacteriocins as biopreservatives. Several mechanisms of bacteriocin resistance development have been proposed among various foodborne pathogens. The acquiring of resistance to bacteriocins can significantly affect physiological activity profile of bacteria, alter cell-envelope lipid composition, and also modify the antibiotic susceptibility/resistance profile of bacteria. This article presents a brief review on the scientific research about the various possible mechanisms involved in the development of resistance to nisin and Class IIa bacteriocins among the foodborne pathogens.

  5. Combating multidrug-resistant Gram-negative bacteria with structurally nanoengineered antimicrobial peptide polymers.

    PubMed

    Lam, Shu J; O'Brien-Simpson, Neil M; Pantarat, Namfon; Sulistio, Adrian; Wong, Edgar H H; Chen, Yu-Yen; Lenzo, Jason C; Holden, James A; Blencowe, Anton; Reynolds, Eric C; Qiao, Greg G

    2016-09-12

    With the recent emergence of reports on resistant Gram-negative 'superbugs', infections caused by multidrug-resistant (MDR) Gram-negative bacteria have been named as one of the most urgent global health threats due to the lack of effective and biocompatible drugs. Here, we show that a class of antimicrobial agents, termed 'structurally nanoengineered antimicrobial peptide polymers' (SNAPPs) exhibit sub-μM activity against all Gram-negative bacteria tested, including ESKAPE and colistin-resistant and MDR (CMDR) pathogens, while demonstrating low toxicity. SNAPPs are highly effective in combating CMDR Acinetobacter baumannii infections in vivo, the first example of a synthetic antimicrobial polymer with CMDR Gram-negative pathogen efficacy. Furthermore, we did not observe any resistance acquisition by A. baumannii (including the CMDR strain) to SNAPPs. Comprehensive analyses using a range of microscopy and (bio)assay techniques revealed that the antimicrobial activity of SNAPPs proceeds via a multimodal mechanism of bacterial cell death by outer membrane destabilization, unregulated ion movement across the cytoplasmic membrane and induction of the apoptotic-like death pathway, possibly accounting for why we did not observe resistance to SNAPPs in CMDR bacteria. Overall, SNAPPs show great promise as low-cost and effective antimicrobial agents and may represent a weapon in combating the growing threat of MDR Gram-negative bacteria.

  6. Incidence and Diversity of Antimicrobial Multidrug Resistance Profiles of Uropathogenic Bacteria

    PubMed Central

    Linhares, Inês; Raposo, Teresa; Rodrigues, António

    2015-01-01

    The aim of this study was to assess the most frequent multidrug resistant (MDR) profiles of the main bacteria implicated in community-acquired urinary tract infections (UTI). Only the MDR profiles observed in, at least, 5% of the MDR isolates were considered. A quarter of the bacteria were MDR and the most common MDR profile, including resistance to penicillins, quinolones, and sulfonamides (antibiotics with different mechanisms of action, all mainly recommended by the European Association of Urology for empirical therapy of uncomplicated UTI), was observed, alone or in association with resistance to other antimicrobial classes, in the main bacteria implicated in UTI. The penicillin class was included in all the frequent MDR profiles observed in the ten main bacteria and was the antibiotic with the highest prescription during the study period. The sulfonamides class, included in five of the six more frequent MDR profiles, was avoided between 2000 and 2009. The results suggest that the high MDR percentage and the high diversity of MDR profiles result from a high prescription of antibiotics but also from antibiotic-resistant genes transmitted with other resistance determinants on mobile genetic elements and that the UTI standard treatment guidelines must be adjusted for the community of Aveiro District. PMID:25834814

  7. Spatial Patterns in Antibiotic Resistance among Stream Bacteria: Effects of Industrial Pollution

    PubMed Central

    McArthur, J Vaun; Tuckfield, R. Cary

    2000-01-01

    The spatial distribution of antibiotic resistance to streptomycin and kanamycin was examined in natural bacterial communities of two streams. The proportion of resistant bacteria was substantially higher (P < 0.05) in the midreaches of an industrially perturbed stream, but no such pattern was apparent in an undisturbed reference stream. The highest relative frequency of resistance was found at the confluence of a tributary draining a nuclear reactor and industrial complex. Antibiotic resistance increased with distance upstream from the confluence and was positively correlated (r2 = 0.54, P = 0.023) with mercury concentrations in the sediments. When the data for two years were compared, this pattern was stable for streptomycin resistance (paired t test, P < 0.05) but not for kanamycin resistance (P > 0.05). Our results imply that heavy metal pollution may contribute to increased antibiotic resistance through indirect selection. PMID:10966382

  8. Antimicrobial metallopolymers and their bioconjugates with conventional antibiotics against multidrug-resistant bacteria.

    PubMed

    Zhang, Jiuyang; Chen, Yung Pin; Miller, Kristen P; Ganewatta, Mitra S; Bam, Marpe; Yan, Yi; Nagarkatti, Mitzi; Decho, Alan W; Tang, Chuanbing

    2014-04-02

    Bacteria are now becoming more resistant to most conventional antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA), a complex of multidrug-resistant Gram-positive bacterial strains, has proven especially problematic in both hospital and community settings by deactivating conventional β-lactam antibiotics, including penicillins, cephalosporins, and carbapenems, through various mechanisms, resulting in increased mortality rates and hospitalization costs. Here we introduce a class of charged metallopolymers that exhibit synergistic effects against MRSA by efficiently inhibiting activity of β-lactamase and effectively lysing bacterial cells. Various conventional β-lactam antibiotics, including penicillin-G, amoxicillin, ampicillin, and cefazolin, are protected from β-lactamase hydrolysis via the formation of unique ion-pairs between their carboxylate anions and cationic cobaltocenium moieties. These discoveries could provide a new pathway for designing macromolecular scaffolds to regenerate vitality of conventional antibiotics to kill multidrug-resistant bacteria and superbugs.

  9. Antimicrobial Organometallic Dendrimers with Tunable Activity against Multidrug-Resistant Bacteria.

    PubMed

    Abd-El-Aziz, Alaa S; Agatemor, Christian; Etkin, Nola; Overy, David P; Lanteigne, Martin; McQuillan, Katherine; Kerr, Russell G

    2015-11-09

    Multidrug-resistant pathogens are an increasing threat to public health. In an effort to curb the virulence of these pathogens, new antimicrobial agents are sought. Here we report a new class of antimicrobial organometallic dendrimers with tunable activity against multidrug-resistant Gram-positive bacteria that included methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. Mechanistically, these redox-active, cationic organometallic dendrimers induced oxidative stress on bacteria and also disrupted the microbial cell membrane. The minimum inhibitory concentrations, which provide a quantitative measure of the antimicrobial activity of these dendrimers, were in the low micromolar range. AlamarBlue cell viability assay also confirms the antimicrobial activity of these dendrimers. Interestingly, these dendrimers were noncytotoxic to epidermal cell lines and to mammalian red blood cells, making them potential antimicrobial platforms for topical applications.

  10. Prevalence of antibiotic-resistant bacteria in three different aquatic environments over three seasons.

    PubMed

    Mohanta, Tandra; Goel, Sudha

    2014-08-01

    The objective of this study was to evaluate the impact of urbanization and seasonal changes on the prevalence of antibiotic-resistant bacteria in different aqueous environments. To this end, bacteria were isolated from three different water sources: the River Hooghly in Kolkata, River Kangsabati and groundwater from Kharagpur, West Bengal over three seasons: post-monsoon, winter and summer in 2012-2013. A total of 163 Gram-negative bacteria were isolated from the River Hooghly (n = 138), River Kangsabati (n = 13) and groundwater (n = 12). Antibiotic susceptibility testing was done using 12 antibiotic discs. The percentages of multiple antibiotic-resistant (MAR) bacteria at the three sampling locations were found to be 71.01 % (98/138) for River Hooghly, 15.38 % (2/13) for River Kangsabati and 8.33 % (1/12) for groundwater. Prevalence of MAR bacteria with respect to the three seasons were the following: 73.58 % in post-monsoon, 59.26 % in winter and 53.57 % in summer. Antibiotic resistance index (ARI) was calculated for each location and each season. In general, ARI values for all the River Hooghly samples were >0.2 while those for the River Kangsabati and groundwater in Kharagpur were always <0.2 indicating greater exposure to antibiotics and subsequent resistance in bacteria from the River Hooghly compared to the other two locations. In addition, percentage of MAR and ARI values followed the trend: post-monsoon > winter > summer. This may be due to the additional terrestrial resistants that get swept along with surface runoff during the monsoons.

  11. Multidrug Resistance in Quinolone-Resistant Gram-Negative Bacteria Isolated from Hospital Effluent and the Municipal Wastewater Treatment Plant.

    PubMed

    Vaz-Moreira, Ivone; Varela, Ana Rita; Pereira, Thamiris V; Fochat, Romário C; Manaia, Célia M

    2016-03-01

    This study is aimed to assess if hospital effluents represent an important supplier of multidrug-resistant (MDR) Gram-negative bacteria that, being discharged in the municipal collector, may be disseminated in the environment and bypassed in water quality control systems. From a set of 101 non-Escherichia coli Gram-negative bacteria with reduced susceptibility to quinolones, was selected a group of isolates comprised by those with the highest indices of MDR (defined as nonsusceptibility to at least one agent in six or more antimicrobial categories, MDR ≥6) or resistance to meropenem or ceftazidime (n = 25). The isolates were identified and characterized for antibiotic resistance phenotype, plasmid-mediated quinolone resistance (PMQR) genes, and other genetic elements and conjugative capacity. The isolates with highest MDR indices were mainly from hospital effluent and comprised ubiquitous bacterial groups of the class Gammaproteobacteria, of the genera Aeromonas, Acinetobacter, Citrobacter, Enterobacter, Klebsiella, and Pseudomonas, and of the class Flavobacteriia, of the genera Chryseobacterium and Myroides. In this group of 25 strains, 19 identified as Gammaproteobacteria harbored at least one PMQR gene (aac(6')-Ib-cr, qnrB, qnrS, or oqxAB) or a class 1 integron gene cassette encoding aminoglycoside, sulfonamide, or carbapenem resistance. Most of the E. coli J53 transconjugants with acquired antibiotic resistance resulted from conjugation with Enterobacteriaceae. These transconjugants demonstrated acquired resistance to a maximum of five classes of antibiotics, one or more PMQR genes and/or a class 1 integron gene cassette. This study shows that ubiquitous bacteria, other than those monitored in water quality controls, are important vectors of antibiotic resistance and can be disseminated from hospital effluent to aquatic environments. This information is relevant to support management options aiming at the control of this public health problem.

  12. Multidrug resistance in hydrocarbon-tolerant Gram-positive and Gram-negative bacteria.

    PubMed

    Stancu, Mihaela Marilena; Grifoll, Magdalena

    2011-01-01

    New Gram-positive and Gram-negative bacteria were isolated from Poeni oily sludge, using enrichment procedures. The six Gram-positive strains belong to Bacillus, Lysinibacillus and Rhodococcus genera. The eight Gram-negative strains belong to Shewanella, Aeromonas, Pseudomonas and Klebsiella genera. Isolated bacterial strains were tolerant to saturated (i.e., n-hexane, n-heptane, n-decane, n-pentadecane, n-hexadecane, cyclohexane), monoaromatic (i.e., benzene, toluene, styrene, xylene isomers, ethylbenzene, propylbenzene) and polyaromatic (i.e., naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons, and also resistant to different antimicrobial agents (i.e., ampicillin, kanamycin, rhodamine 6G, crystal violet, malachite green, sodium dodecyl sulfate). The presence of hydrophilic antibiotics like ampicillin or kanamycin in liquid LB-Mg medium has no effects on Gram-positive and Gram-negative bacteria resistance to toxic compounds. The results indicated that Gram-negative bacteria are less sensitive to toxic compounds than Gram-positive bacteria, except one bacteria belonging to Lysinibacillus genus. There were observed cellular and molecular modifications induced by ampicillin or kanamycin to isolated bacterial strains. Gram-negative bacteria possessed between two and four catabolic genes (alkB, alkM, alkB/alkB1, todC1, xylM, PAH dioxygenase, catechol 2,3-dioxygenase), compared with Gram-positive bacteria (except one bacteria belonging to Bacillus genus) which possessed one catabolic gene (alkB/alkB1). Transporter genes (HAE1, acrAB) were detected only in Gram-negative bacteria.

  13. Antibiotic contamination and occurrence of antibiotic-resistant bacteria in aquatic environments of northern Vietnam.

    PubMed

    Hoa, Phan Thi Phuong; Managaki, Satoshi; Nakada, Norihide; Takada, Hideshige; Shimizu, Akiko; Anh, Duong Hong; Viet, Pham Hung; Suzuki, Satoru

    2011-07-01

    The ubiquitous application and release of antibiotics to the environment can result in bacterial antibiotic resistance, which in turn can be a serious risk to humans and other animals. Southeast Asian countries commonly apply an integrated recycling farm system called VAC (Vegetable, Aquaculture and Caged animal). In the VAC environment, antibiotics are released from animal and human origins, which would cause antibiotic-resistant bacteria (ARB). This study evaluated occurrence of ARB in the VAC environment in northern Vietnam, with quantitative analysis of antibiotic pollution. We found that sulfonamides were commonly detected at all sites. In dry season, while sulfamethazine was a major contaminant in pig farm pond (475-6662 ng/l) and less common in city canal and aquaculture sites, sulfamethoxazole was a major one in city canal (612-4330 ng/l). Erythromycin (154-2246 ng/l) and clarithromycin (2.8-778 ng/ml) were the common macrolides in city canal, but very low concentrations in pig farm pond and aquaculture sites. High frequencies of sulfamethoxazole-resistant bacteria (2.14-94.44%) were found whereas the occurrence rates of erythromycin-resistant bacteria were lower (<0.01-38.8%). A positive correlation was found between sulfamethoxazole concentration and occurrence of sulfamethoxazole-resistant bacteria in dry season. The sulfamethoxazole-resistant isolates were found to belong to 25 genera. Acinetobacter and Aeromonas were the major genera. Twenty three of 25 genera contained sul genes. This study showed specific contamination patterns in city and VAC environments and concluded that ARB occurred not only within contaminated sites but also those less contaminated. Various species can obtain resistance in VAC environment, which would be reservoir of drug resistance genes. Occurrence of ARB is suggested to relate with rainfall condition and horizontal gene transfer in diverse microbial community. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Is screening patients for antibiotic-resistant bacteria justified in the Indian context?

    PubMed

    Bhattacharya, S

    2011-01-01

    Infection with multi-antibiotic-resistant bacteria is a common clinical problem in India. In some countries and centres, screening patients to detect colonisation by these organisms is used to determine specific interventions such as decolonisation treatment, prophylactic antibiotics prior to surgical interventions or for selection of empirical antibiotic therapy, and to isolate patients so that transmission of these difficult to treat organisms to other patients could be prevented. In India, there is no national guideline or recommendation for screening patients for multi-drug-resistant (MDR) bacteria such as MRSA (methicillin-resistant Staphylococcus aureus), VRE (vancomycin-resistant enterococcus), ESBL (extended spectrum beta-lactamase) or MBL (metallo-beta-lactamase) producers. The present article discusses the relevance of screening patients for multi-antibiotic-resistant bacteria in the Indian context. Literature has been reviewed about antibiotic resistance in India, screening methodology, economic debate about screening. The percentages of strains from various hospitals in India which were reported to be MRSA was between 8 and 71%, those for ESBL between 19 and 60% and carbapenem-resistant Gram-negative bacilli between 5.3 and 59%. There exists culture-based technology for the detection of these resistant organisms from patient samples. For some pathogens, such as MRSA and VRE Polymerase chain reaction-based tests are also becoming available. Screening for MDR bacteria is an option which may be used after appraisal of the resources available, and after exploring possibility of implementing the interventions that may be required after a positive screening test result.

  15. Novel target sites in bacteria for overcoming antibiotic resistance.

    PubMed

    Black, Michael T; Hodgson, John

    2005-07-29

    Resistance to marketed antibiotics continues to increase. During the last 10 years some 200 bacterial genome sequences have become available, giving rise to expectations that genomics would provide a plethora of novel targets and hence a flood of new therapeutic agents. Contrary to some predictions the genomic effort has yet to yield a substantial number of novel class agents in clinical development. What are the reasons for the differences between expectations and reality? This article reviews what has been achieved in the exploitation of bacterial genomes for the discovery of novel antibacterials.

  16. Organic and conventional fruits and vegetables contain equivalent counts of Gram-negative bacteria expressing resistance to antibacterial agents.

    PubMed

    Ruimy, Raymond; Brisabois, Anne; Bernede, Claire; Skurnik, David; Barnat, Saïda; Arlet, Guillaume; Momcilovic, Sonia; Elbaz, Sandrine; Moury, Frédérique; Vibet, Marie-Anne; Courvalin, Patrice; Guillemot, Didier; Andremont, Antoine

    2010-03-01

    Resistance to antibiotics is a major public health problem which might culminate in outbreaks caused by pathogenic bacteria untreatable by known antibiotics. Most of the genes conferring resistance are acquired horizontally from already resistant commensal or environmental bacteria. Food contamination by resistant bacteria might be a significant source of resistance genes for human bacteria but has never been precisely assessed, nor is it known whether organic products differ in this respect from conventionally produced products. We showed here, on a large year-long constructed sample set containing 399 products that, irrespective of their mode of production, raw fruits and vegetables are heavily contaminated by Gram-negative bacteria (GNB) resistant to multiple antibiotics. Most of these bacteria originate in the soil and environment. We focused on non-oxidative GNB resistant to third-generation cephalosporins, because of their potential impact on human health. Among them, species potentially pathogenic for immunocompetent hosts were rare. Of the products tested, 13% carried bacteria producing extended-spectrum beta-lactamases, all identified as Rahnella sp. which grouped into two phylotypes and all carrying the bla(RAHN) gene. Thus, both organic and conventional fruits and vegetables may constitute significant sources of resistant bacteria and of resistance genes.

  17. Colonisation of antibiotic resistant bacteria in a cohort of HIV infected children in Ghana.

    PubMed

    Sampane-Donkor, Eric; Badoe, Ebenezer Vincent; Annan, Jennifer Adoley; Nii-Trebi, Nicholas

    2017-01-01

    Antibiotic use not only selects for resistance in pathogenic bacteria, but also in commensal flora of exposed individuals. Little is known epidemiologically about antibiotic resistance in relation to people with HIV infection in sub-Saharan Africa. This study investigated the carriage of antibiotic resistant bacteria among HIV infected children at a tertiary hospital in Ghana. One hundred and eighteen HIV positive children were recruited at the Korle-Bu Teaching Hospital in Ghana and nasopharyngeal specimens were collected from them. The specimens were cultured for bacteria, and the isolates were identified by standard microbiological methods. Antibiotic susceptibility tests were carried out on selected bacterial organisms by the Kirby Bauer method. Bacteria isolated from the study subjects included Moraxella catarrhalis (39.8%), coagulase negative staphylococci (33.1%), Streptococcus pneumoniae (30.5%), diptheroids (29.7%), viridian streptococci (27.1%), Staphylococcus aureus (22.0%), Citrobacter spp. (4.2%) and Neisseria meningitidis (0.9%). Prevalence of antibiotic resistance of S. pneumoniae ranged from 5.6% (ceftriaxone) to 58.3% (cotrimoxazole), M. catarrhalis ranged from 2.1% (gentamicin) to 80.6% (ampicillin), and S. aureus ranged from 7.7% (cefoxitin) to 100% (penicillin). The prevalence of multiple drug resistance was 16.7% for S. pneumoniae, 57.4% for M. catarrhalis and 84.6% for S. aureus. HIV infected children in the study area commonly carry multi-drug resistant isolates of several pathogenic bacteria such as S. aureus and S. pneumoniae. Infections arising in these patients that are caused by S. aureus and S. pneumoniae could be treated with ceftriaxone and cefoxitin respectively.

  18. Independent behavior of commensal flora for carriage of fluoroquinolone-resistant bacteria in patients at admission.

    PubMed

    de Lastours, Victoire; Chau, Françoise; Tubach, Florence; Pasquet, Blandine; Ruppé, Etienne; Fantin, Bruno

    2010-12-01

    The important role of commensal flora as a natural reservoir of bacterial resistance is now well established. However, whether the behavior of each commensal flora is similar to that of other floras in terms of rates of carriage and risk factors for bacterial resistance is unknown. During a 6-month period, we prospectively investigated colonization with fluoroquinolone-resistant bacteria in the three main commensal floras from hospitalized patients at admission, targeting Escherichia coli in the fecal flora, coagulase-negative Staphylococcus (CNS) in the nasal flora, and α-hemolytic streptococci in the pharyngeal flora. Resistant strains were detected on quinolone-containing selective agar. Clinical and epidemiological data were collected. A total of 555 patients were included. Carriage rates of resistance were 8.0% in E. coli, 30.3% in CNS for ciprofloxacin, and 27.2% in streptococci for levofloxacin; 56% of the patients carried resistance in at least one flora but only 0.9% simultaneously in all floras, which is no more than random. Risk factors associated with the carriage of fluoroquinolone-resistant strains differed between fecal E. coli (i.e., colonization by multidrug-resistant bacteria) and nasal CNS (i.e., age, coming from a health care facility, and previous antibiotic treatment with a fluoroquinolone) while no risk factors were identified for pharyngeal streptococci. Despite high rates of colonization with fluoroquinolone-resistant bacteria, each commensal flora behaved independently since simultaneous carriage of resistance in the three distinct floras was uncommon, and risk factors differed. Consequences of environmental selective pressures vary in each commensal flora according to its local specificities (clinical trial NCT00520715 [http://clinicaltrials.gov/ct2/show/NCT00520715]).

  19. Multidrug resistant bacteria isolated from cockroaches in long-term care facilities and nursing homes.

    PubMed

    Pai, Hsiu-Hua

    2013-01-01

    Residents in long-term care facilities and nursing homes have a relative higher risk for infections. The nocturnal and filthy habits of cockroaches may be ideal disseminators of pathogenic microorganisms in these institutions. This study was designed to determine the infestation and vector potential of cockroaches under this institutional environment. Cockroaches were collected from 69 long-term care facilities and nursing homes in Kaohsiung City. Risk factors related to cockroach infestation were determined by questionnaire survey. In addition, bacteria were isolated and identified from the alimentary tract and external surface of these insects. Antibiotic resistances of these microorganisms were then determined. Cockroach infestation was found in 45 (65.2%) institutions and 558 cockroaches (119 Periplaneta americana and 439 Blattella germanica) were collected. A significant association was found between cockroach infestation and indoor environmental sanitation. From 250 adult cockroaches, 38 species of gram-negative bacteria, 20 species of glucose non-fermenter bacilli and 6 species of gram-positive bacteria were isolated. Moreover, antibiotic resistances were found among the bacteria isolated. These findings indicate that cockroaches have the potential in transmitting pathogenic bacteria with multidrug resistances in long-term care facilities and nursing homes.

  20. Antibiotic concentration and antibiotic-resistant bacteria in two shallow urban lakes after stormwater event.

    PubMed

    Zhang, Songhe; Pang, Si; Wang, PeiFang; Wang, Chao; Han, Nini; Liu, Bin; Han, Bing; Li, Yi; Anim-Larbi, Kwaku

    2016-05-01

    Stormwater runoff is generally characterized as non-point source pollution. In the present study, antibiotic concentration and antibiotic susceptibilities of cultivable heterotrophic bacteria were investigated in two small shallow urban lakes before and after strong storm event. Several antibiotics, lactose-fermenting bacteria and cultivable heterotrophic bacteria concentrations increased in surface water and/or surface sediment of two small urban lakes (Lake Xuanwu and Wulongtan) after strong storm event. In general, the frequencies of bacteria showing resistance to nine antibiotics increased after storm event. Based on the 16S rRNA genes of 50 randomly selected isolates from each water sample of two lakes, Aeromonas and Bacillus were dominant genera in samples from two lakes, while genera Proteus and Lysinibacillus were the third abundant genera in Lake Xuanwu and Wulongtu, respectively. Presences of nine antibiotic resistance genes (ARGs) in the 100 isolates were detected and most of these isolates harbored at least two ARGs with different functions. The detection frequency of ARGs in Gram-negative isolates was higher than that in Gram-positive isolates. The most prevalent integron in 100 isolates was int(II) (n = 28), followed by int(I) (n = 17) and int(III) (n = 17). Our results indicate that strong storm events potentially contribute to the transfer of ARGs and antibiotic-resistant bacteria from land-sewer system to the urban Lakes.

  1. The role of surveillance systems in confronting the global crisis of antibiotic-resistant bacteria

    PubMed Central

    Perez, Federico; Villegas, Maria Virginia

    2015-01-01

    Purpose of Review It is widely accepted that infection control, advanced diagnostics, and novel therapeutics are crucial to mitigate the impact of antibiotic-resistant bacteria. The role of global, national and regional surveillance systems as part of the response to the challenge posed by antibiotic resistance is not sufficiently highlighted. We provide an overview of contemporary surveillance programs, with emphasis on Gram-negative bacteria. Recent Findings The World Health Organization and public health agencies in Europe and the United States recently published comprehensive surveillance reports. These highlight the emergence and dissemination of carbapenem-resistant Enterobacteriaceae (CRE) and other multidrug resistant Gram-negative bacteria. In Israel, public health action to control CRE, especially Klebsiella pneumoniae carbapenemase (KPC) producing-Klebsiella pneumoniae, has advanced together with a better understanding of its epidemiology. Surveillance models adapted to the requirements and capacities of each country are in development. Summary Robust surveillance systems are essential to combat antibiotic resistance, and need to emphasize a “One Health” approach. Refinements in surveillance will come from advances in bioinformatics and genomics that permit the integration of global and local information about antibiotic consumption in humans and animals, molecular mechanisms of resistance, and bacterial genotyping. PMID:26098505

  2. Detection of antibiotic resistant Escherichia Coli bacteria using infrared microscopy and advanced multivariate analysis.

    PubMed

    Salman, Ahmad; Sharaha, Uraib; Rodriguez-Diaz, Eladio; Shufan, Elad; Riesenberg, Klaris; Bigio, Irving J; Huleihel, Mahmoud

    2017-06-12

    Bacterial resistance to antibiotics is becoming a global health-care problem. Bacteria are involved in many diseases, and antibiotics have been the most effective treatment for them. It is essential to treat an infection with an antibiotic to which the infecting bacteria is sensitive; otherwise, the treatment is not effective and may lead to life-threatening progression of disease. Classical microbiology methods that are used for determination of bacterial susceptibility to antibiotics are time consuming, accounting for problematic delays in the administration of appropriate drugs. Infrared-absorption microscopy is a sensitive and rapid method, enabling the acquisition of biochemical information from cells at the molecular level. The combination of Fourier transform infrared (FTIR) microscopy with new statistical classification methods for spectral analysis has become a powerful technique, with the ability to detect structural molecular changes associated with resistivity of bacteria to antibiotics. It was possible to differentiate between isolates of Escherichia (E.) coli that were sensitive or resistant to different antibiotics with good accuracy. The objective computational classifier, based on infrared absorption spectra, is highly sensitive to the subtle infrared spectral changes that correlate with molecular changes associated with resistivity. These changes enable differentiating between the resistant and sensitive E. coli isolates within a few minutes, following the initial culture. This study provides proof-of-concept evidence for the translational potential of this spectroscopic technique in the clinical management of bacterial infections, by characterizing and classifying antibiotic resistance in a much shorter time than possible with current standard laboratory methods.

  3. Dental plaque bacteria with reduced susceptibility to chlorhexidine are multidrug resistant.

    PubMed

    Saleem, Hafiz Ghulam Murtaza; Seers, Christine Ann; Sabri, Anjum Nasim; Reynolds, Eric Charles

    2016-09-15

    Chlorhexidine (CHX) is used in oral care products to help control dental plaque. In this study dental plaque bacteria were grown on media containing 2 μg/ml chlorhexidine gluconate to screen for bacteria with reduced CHX susceptibility. The isolates were characterized by 16S rRNA gene sequencing and antibiotic resistance profiles were determined using the disc diffusion method. The isolates were variably resistant to multiple drugs including ampicillin, kanamycin, gentamicin and tetracycline. Two species, Chryseobacterium culicis and Chryseobacterium indologenes were able to grow planktonically and form biofilms in the presence of 32 μg/ml CHX. In the CHX and multidrug resistant C. indologenes we demonstrated a 19-fold up-regulation of expression of the HlyD-like periplasmic adaptor protein of a tripartite efflux pump upon exposure to 16 μg/ml CHX suggesting that multidrug resistance may be mediated by this system. Exposure of biofilms of these resistant species to undiluted commercial CHX mouthwash for intervals from 5 to 60 s indicated that the mouthwash was unlikely to eliminate them from dental plaque in vivo. The study highlights the requirement for increased vigilance of the presence of multidrug resistant bacteria in dental plaque and raises a potential risk of long-term use of oral care products containing antimicrobial agents for the control of dental plaque.

  4. [Distribution and removal of anaerobic antibiotic resistant bacteria during mesophilic anaerobic digestion of sewage sludge].

    PubMed

    Tong, Juan; Wang, Yuan-Yue; Wei Yuan, Song

    2014-10-01

    Sewage sludge is one of the major sources that releasing antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG) into the environment since it contains large amount of ARB, but there is little information about the fate of the anaerobic ARB in the anaerobic digestion of sewage sludge. Therefore, the distribution, removal and seasonal changes of tetracycline and β-lactam antibiotics resistant bacteria in the mesophilic egg-shaped digesters of a municipal wastewater treatment plant were investigated for one year in this study. Results showed that there were higher amounts of ARB and higher resistance rate of β-lactam antibiotics than that of tetracycline antibiotics in the sewage sludge. All ARB could be significantly reduced during the mesophilic anaerobic digestion process by 1.48-1.64 log unit (P < 0.05). Notably, the ampicillin and cephalothin resistance rates were significantly increased after anaerobic digestion by 12.0% and 14.3%, respectively (P < 0.05). The distribution of ARB in the sewage sludge had seasonal change characteristics. Except for chlorotetracycline resistant bacteria, there were more ARB in the sewage sludge in cold season than in warm season (P < 0.05).

  5. Photodynamic UVA-riboflavin bacterial elimination in antibiotic-resistant bacteria.

    PubMed

    Makdoumi, Karim; Bäckman, Anders

    2016-09-01

    To evaluate the bactericidal effect of clinical ultraviolet A (UVA) settings used in photoactivated chromophore for infectious keratitis (PACK)-collagen cross-linking (CXL) in antibiotic-resistant and non-resistant bacterial strains. Well-characterized bacterial strains from clinical isolates, without and with antibiotic resistance, were studied in a pairwise comparison. The evaluated pathogens were Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis. Bacteria were dispersed in PBS and diluted to a concentration of approximately 4 × 10(5) /ml. Riboflavin was added to a concentration of 0.01%. By spreading the solution on a microscope slide, a fluid film layer, with a thickness of around 400 mm, was formed and UVA exposure followed. Eight separate exposures were made for each strain (n = 8). The degree of elimination in resistant and non-resistant pathogens was compared. The bactericidal efficacy of exposure differed between the tested microorganisms, and the mean elimination ranged between 60 and 92%, being most extensive in both of the evaluated Pseudomonas strains and least in the E. faecalis strains. Similar reductions were seen in antibiotic-resistant and non-resistant strains, with the exception of S. aureus, in which the resistant strain metchicillin-resistant Staphylococcus aureus (MRSA) was eradicated in a greater extent than the non-resistant strain (P = 0.030). UVA-riboflavin settings used in PACK-CXL are effective in reducing both antibiotic-resistant and non-resistant bacteria. Antibiotic resistance does not appear to be protective against the photooxidative exposure. © 2016 Royal Australian and New Zealand College of Ophthalmologists.

  6. Incidence of antimicrobial-resistance genes and integrons in antibiotic-resistant bacteria isolated from eels and aquaculture ponds.

    PubMed

    Lin, Mao; Wu, Xiaomei; Yan, Qingpi; Ma, Ying; Huang, Lixing; Qin, Yingxue; Xu, Xiaojin

    2016-07-07

    The overuse of antimicrobials in aquaculture has promoted the selection of antimicrobial-resistant bacteria. Here we investigated the abundance of antimicrobial-resistance genes and integrons in 108 strains of antibiotic-resistant bacteria isolated from eels and aquaculture ponds in China. Conventional PCR was implemented to examine common antibiotic-resistance genes, integrons, and their gene cassette arrays. The results showed that the antibiotic-resistance genes blaTEM, tetC, sulI, aadA, floR, and qnrB were detected at high percentages, as were a number of other resistance genes. Class I integrons were present in 79.63% of the strains, and 10 out of 108 isolates carried class II integrons. Class III integrons were not detected. Three strains carried both class I and class II integrons, and 73.26% of the class I integron-positive isolates contained the qacEΔ1/sul1 gene. Fourteen types of integron cassette arrays were found among class I integron-positive isolates. A new array, dfrB4-catB3-blaOXA-10-aadA1, was discovered in this study. The gene cassette array dfrA12-orfF-aadA2 was the most widely distributed. In summary, 23 different gene cassettes encoding resistance to 8 classes of antibiotics were identified in the class I integrons, and the main cassettes contained genes encoding resistance to aminoglycosides (aad) and trimethoprim (dfr). All class II integron-positive strains had only a single gene cassette array, viz. dfrA1-catB2-sat2-aadA1. High levels of antimicrobial-resistance genes and integrons in eels and auqauculture ponds suggest that the overuse of antimicrobials should be strictly controlled and that the levels of bacterial antimicrobial-resistance genes in aquaculture should be monitored.

  7. A Reservoir of Drug-Resistant Pathogenic Bacteria in Asymptomatic Hosts

    PubMed Central

    Perron, Gabriel G.; Quessy, Sylvain; Bell, Graham

    2008-01-01

    The population genetics of pathogenic bacteria has been intensively studied in order to understand the spread of disease and the evolution of virulence and drug resistance. However, much less attention has been paid to bacterial carriage populations, which inhabit hosts without producing disease. Since new virulent strains that cause disease can be recruited from the carriage population of bacteria, our understanding of infectious disease is seriously incomplete without knowledge on the population structure of pathogenic bacteria living in an asymptomatic host. We report the first extensive survey of the abundance and diversity of a human pathogen in asymptomatic animal hosts. We have found that asymptomatic swine from livestock productions frequently carry populations of Salmonella enterica with a broad range of drug-resistant strains and genetic diversity greatly exceeding that previously described. This study shows how agricultural practice and human intervention may lead and influence the evolution of a hidden reservoir of pathogens, with important implications for human health. PMID:19015729

  8. Isolation of bacteria with antibiotic resistance from household cockroaches (Periplaneta americana and Blattella germanica).

    PubMed

    Pai, Hsiu-Hua; Chen, Wei-Chen; Peng, Chien-Fang

    2005-03-01

    Cockroaches may harbor and disseminate microorganisms to the environment. In this study, Periplaneta americana and Blattella germanica were collected from 40 households in Kaohsiung City and Kaohsiung County, Taiwan. Cockroach infestation was found in 50% of the studied households and 226 cockroaches (123 P. americana and 103 B. germanica) collected by trapping. P. americana was more often found in the kitchen (70.7%) whereas B. germanica in the storage room (51.5%) and kitchen (36.9%). There was no significant difference between the percentages of P. americana (99.9%) and B. germanica (98.0%) carrying bacteria. A total of 25 species of bacteria was isolated from P. americana and only 21 from B. germanica. Antibiotic resistance was found in Staphylococcus aureus, Enterococcus species, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Serratia marcescens, and Proteus species isolated from the cockroaches. These findings suggest a potential role of cockroaches in the transmission of pathogenic bacteria with antibiotic resistance in households.

  9. Potential role of intratumor bacteria in mediating tumor resistance to the chemotherapeutic drug gemcitabine.

    PubMed

    Geller, Leore T; Barzily-Rokni, Michal; Danino, Tal; Jonas, Oliver H; Shental, Noam; Nejman, Deborah; Gavert, Nancy; Zwang, Yaara; Cooper, Zachary A; Shee, Kevin; Thaiss, Christoph A; Reuben, Alexandre; Livny, Jonathan; Avraham, Roi; Frederick, Dennie T; Ligorio, Matteo; Chatman, Kelly; Johnston, Stephen E; Mosher, Carrie M; Brandis, Alexander; Fuks, Garold; Gurbatri, Candice; Gopalakrishnan, Vancheswaran; Kim, Michael; Hurd, Mark W; Katz, Matthew; Fleming, Jason; Maitra, Anirban; Smith, David A; Skalak, Matt; Bu, Jeffrey; Michaud, Monia; Trauger, Sunia A; Barshack, Iris; Golan, Talia; Sandbank, Judith; Flaherty, Keith T; Mandinova, Anna; Garrett, Wendy S; Thayer, Sarah P; Ferrone, Cristina R; Huttenhower, Curtis; Bhatia, Sangeeta N; Gevers, Dirk; Wargo, Jennifer A; Golub, Todd R; Straussman, Ravid

    2017-09-15

    Growing evidence suggests that microbes can influence the efficacy of cancer therapies. By studying colon cancer models, we found that bacteria can metabolize the chemotherapeutic drug gemcitabine (2',2'-difluorodeoxycytidine) into its inactive form, 2',2'-difluorodeoxyuridine. Metabolism was dependent on the expression of a long isoform of the bacterial enzyme cytidine deaminase (CDDL), seen primarily in Gammaproteobacteria. In a colon cancer mouse model, gemcitabine resistance was induced by intratumor Gammaproteobacteria, dependent on bacterial CDDL expression, and abrogated by cotreatment with the antibiotic ciprofloxacin. Gemcitabine is commonly used to treat pancreatic ductal adenocarcinoma (PDAC), and we hypothesized that intratumor bacteria might contribute to drug resistance of these tumors. Consistent with this possibility, we found that of the 113 human PDACs that were tested, 86 (76%) were positive for bacteria, mainly Gammaproteobacteria. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  10. Amoebae-resisting bacteria isolated from human nasal swabs by amoebal coculture.

    PubMed

    Greub, Gilbert; La Scola, Bernard; Raoult, Didier

    2004-03-01

    Amoebae feed on bacteria, and few bacteria can resist their microbicidal ability. Amoebal coculture could therefore be used to selectively grow these amoebae-resisting bacteria (ARB), which may be human pathogens. To isolate new ARB, we performed amoebal coculture from 444 nasal samples. We recovered 7 (1.6%) ARB from 444 nasal swabs, including 4 new species provisionally named Candidatus Roseomonas massiliae, C. Rhizobium massiliae, C. Chryseobacterium massiliae, and C. Amoebinatus massiliae. The remaining isolates were closely related to Methylobacterium extorquens, Bosea vestrii, and Achromobacter xylosoxidans. Thus, amoebal coculture allows the recovery of new bacterial species from heavily contaminated samples and might be a valuable approach for the recovery of as-yet unrecognized emerging pathogens from clinical specimens.

  11. [Psychological impacts of being a carrier of multi-drug resistant bacteria].

    PubMed

    Pires, Elisabete; Frange, Pierre; Henry, Benoît; Lortholary, Olivier; Reichert, Catherine

    2015-01-01

    Learning that they are a carrier of multi-drug resistant bacteria and being placed in isolation to prevent transmission has significant psychological repercussions for the patient and their families. Through therapeutic education, caregivers adapt their support to the patient's experience, raising their awareness of prevention. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  12. Broad Specificity Efflux pumps and Their Role in Multidrug Resistance of Gram Negative Bacteria

    PubMed Central

    Nikaido, Hiroshi; Pagès, Jean-Marie

    2013-01-01

    Antibiotic resistance mechanisms reported in Gram-negative bacteria are producing a worldwide health problem. The continuous dissemination of «multi-drug resistant» (MDR) bacteria drastically reduces the efficacy of our antibiotic “arsenal” and consequently increases the frequency of therapeutic failure. In MDR bacteria, the over-expression of efflux pumps that expel structurally-unrelated drugs contributes to the reduced susceptibility by decreasing the intracellular concentration of antibiotics. During the last decade, several clinical data indicate an increasing involvement of efflux pumps in the emergence and dissemination of resistant Gram-negative bacteria. It is necessary to clearly define the molecular, functional and genetic bases of the efflux pump in order to understand the translocation of antibiotic molecules through the efflux transporter. The recent investigation on the efflux pump AcrB at its structural and physiological level, including the identification of drug affinity sites and kinetic parameters for various antibiotics, may open the way to rationally develop an improved new generation of antibacterial agents as well as efflux inhibitors in order to efficiently combat efflux-based resistance mechanisms. PMID:21707670

  13. Distribution of tetracycline- and tylosin-resistance genes in bacteria from soils exposed to swine effluent

    USDA-ARS?s Scientific Manuscript database

    The application of animal waste from large-scale production facilities to cropland is a common means of manure disposal and nutrient recycling. In addition to the high nutrient load, antibiotic residues and antibiotic-resistant bacteria enter into the environment through this process. As yet, it i...

  14. Multidrug resistant gram-negative bacteria in clinical isolates from Karachi.

    PubMed

    Saeed, Asma; Khatoon, Hajra; Ansari, Fasihuddin Ahmed

    2009-01-01

    A total of 54 gram-negative bacteria obtained from various pathological labs and hospitals of Karachi were screened for their resistance to ampicillin, chloramphenicol, gentamycin, kanamycin, neomycin, streptomycin and tetracycline antibiotics. Of the 54 bacteria, 50 were resistant to one or more antibiotics. Among the resistant bacteria, 13 out of 28 were found to transfer their resistances by conjugation. This indicates that at least 46% of clinical gram-negative bacteria in Karachi possess various types of transferable R plasmids, such as pAK5, pAK9, pAK10, pAK11, pAK12, pAK13, pAK14, pAK15, pAK16, pAK17, pAK18, pAK19, pAK20 and pAK21. The non-conjugative R plasmids included pMT14 and pZ26. Only pAK15 showed 26% segregation even after 20 consecutive transfers in plain broth (spontaneous segregation) whereas only pAK15 and pAK16 showed any significant loss of their markers in curing by acridine orange. The stability of R plasmids is more dangerous from clinical point of view.

  15. Recycling antibiotics into GUMBOS: A new combination strategy to combat multi-drug resistant bacteria

    USDA-ARS?s Scientific Manuscript database

    The emergence of multi-drug resistant bacteria, coupled with the lack of new antibiotics in development, is fast evolving into a global crisis. New strategies utilizing existing antibacterial agents are urgently needed. We propose one such strategy in which four outmoded ß-lactam antibiotics (amp...

  16. [Caring for a patient carrying multi-drug resistant bacteria at home].

    PubMed

    Kereun, François

    2015-01-01

    Private practice health professionals play a role in the fight against healthcare-associated infections. The management of the home care of a patient carrying multi-drug resistant bacteria reveals the weaknesses in the community-hospital link. Providing care in complete safety for the caregiver as well as the patient is a major challenge. A private practice nurse shares his experience.

  17. The use of minimum selectable concentrations (MSCs) for determining the selection of antimicrobial resistant bacteria.

    PubMed

    Khan, Sadia; Beattie, Tara K; Knapp, Charles W

    2017-03-01

    The use of antimicrobial compounds is indispensable in many industries, especially drinking water production, to eradicate microorganisms. However, bacterial growth is not unusual in the presence of disinfectant concentrations that would be typically lethal, as bacterial populations can develop resistance. The common metric of population resistance has been based on the Minimum Inhibitory Concentration (MIC), which is based on bacteria lethality. However, sub-lethal concentrations may also select for resistant bacteria due to the differences in bacterial growth rates. This study determined the Minimal Selective Concentrations (MSCs) of bacterial populations exposed to free chlorine and monochloramine, representing a metric that possibly better reflects the selective pressures occurring at lower disinfectant levels than MIC. Pairs of phylogenetically similar bacteria were challenged to a range of concentrations of disinfectants. The MSCs of free chlorine and monochloramine were found to range between 0.021 and 0.39 mg L(-1), which were concentrations 1/250 to 1/5 than the MICs of susceptible bacteria (MIC susc ). This study indicates that sub-lethal concentrations of disinfectants could result in the selection of resistant bacterial populations, and MSCs would be a more sensitive indicator of selective pressure, especially in environmental systems.

  18. Effect of manure application rate and timing on the leaching potential of antibiotic resistant bacteria.

    USDA-ARS?s Scientific Manuscript database

    Antibiotics are used in swine production for therapeutic and growth promotion purposes. Because land application is the most common method of disposing of swine lagoon effluent, there exists the potential threat of contaminating the underlying groundwater with antimicrobial-resistant bacteria (ARB) ...

  19. [The risk of infection with patients with multi-drug resistant bacteria in the operating room].

    PubMed

    Latroche, Marie-France; Roche, Géraldine; Velardo, Danielle

    2015-01-01

    The risk of infection in the operating theatre is constant and multifactorial. It can be contained through a prevention process. The organisation, implementation, monitoring and the results of the patient pathway are all sources for the analysis of practices, quality and professional progress in order to limit the risks of transmitting multi-drug or highly resistant bacteria.

  20. Capillary electrophoresis for fast detection of heterogeneous population in colistin-resistant Gram-negative bacteria.

    PubMed

    Sautrey, Guillaume; Duval, Raphaël E; Chevalley, Alicia; Fontanay, Stéphane; Clarot, Igor

    2015-10-01

    It has been shown that diverse strains of bacteria can be separated according to their characteristic surface properties by means of CE. We employed here this analytical technique to the study of colistin-resistance in Gram-negative bacteria, which involves the selection of mutants with modified outer membrane composition resulting in changes of surface cell properties. In the same way as with molecular entities, we performed firstly the validation of an ITP-based CE method for three common pathogenic Gram-negative bacteria namely Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Secondly, we compared the electrophoretic profiles of bacterial samples from a colistin-susceptible clinical isolate of K. pneumoniae and from the corresponding colistin-resistant derivative. By a simple CE run taking a few minutes, the coexistence of several bacterial subpopulations in the colistin-resistant derivative was clearly evidenced. This work encourages further research that would allow applications of CE in clinical laboratory for a daily monitoring of bacterial population in cared patients when "last-chance" colistin treatment is initiated against multidrug-resistant bacteria.

  1. Broad-specificity efflux pumps and their role in multidrug resistance of Gram-negative bacteria.

    PubMed

    Nikaido, Hiroshi; Pagès, Jean-Marie

    2012-03-01

    Antibiotic resistance mechanisms reported in Gram-negative bacteria are causing a worldwide health problem. The continuous dissemination of 'multidrug-resistant' (MDR) bacteria drastically reduces the efficacy of our antibiotic 'arsenal' and consequently increases the frequency of therapeutic failure. In MDR bacteria, the overexpression of efflux pumps that expel structurally unrelated drugs contributes to the reduced susceptibility by decreasing the intracellular concentration of antibiotics. During the last decade, several clinical data have indicated an increasing involvement of efflux pumps in the emergence and dissemination of resistant Gram-negative bacteria. It is necessary to clearly define the molecular, functional and genetic bases of the efflux pump in order to understand the translocation of antibiotic molecules through the efflux transporter. The recent investigation on the efflux pump AcrB at its structural and physiological levels, including the identification of drug affinity sites and kinetic parameters for various antibiotics, may pave the way towards the rational development of an improved new generation of antibacterial agents as well as efflux inhibitors in order to efficiently combat efflux-based resistance mechanisms.

  2. Cross-sectional study of antimicrobial-resistant bacteria in horses. Part 1: Prevalence of antimicrobial-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus.

    PubMed

    Maddox, T W; Clegg, P D; Diggle, P J; Wedley, A L; Dawson, S; Pinchbeck, G L; Williams, N J

    2012-05-01

    The increasing prevalence of antimicrobial-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and antimicrobial-resistant Escherichia coli represents a significant problem. However, the carriage of such bacteria by horses in the UK has not been well characterised. To estimate the prevalence of nasal carriage of MRSA and faecal carriage of antimicrobial-resistant E. coli amongst horses in the general equine community of the mainland UK. A cross-sectional study of horses recruited by 65 randomly selected equine veterinary practices was conducted, with nasal swabs and faecal samples collected. Faecal samples were cultured for antimicrobial-resistant E. coli. Nasal swabs were cultured for staphylococcal species; methicillin-resistant isolates identified as S. aureus were characterised by SCCmec and spa gene typing. Multilevel logistic regression models were used to calculate prevalence estimates with adjustment for clustering at practice and premises levels. Spatial variation in risk of antimicrobial resistance was also examined. In total, 650 faecal samples and 678 nasal swabs were collected from 692 horses located on 525 premises. The prevalence of faecal carriage of E. coli with resistance to any antimicrobial was 69.5% (95% CI 65.9-73.1%) and the prevalence of extended-spectrum β-lactamase (ESBL)-producing E. coli was 6.3% (95% CI 4.1-9.6%). The prevalence of nasal carriage of MRSA was 0.6% (95% CI 0.2-1.5%). Spatial analysis indicated variation across the UK for risk of carriage of resistant and multidrug-resistant (resistant to more than 3 antimicrobial classes) E. coli. Carriage of MRSA by horses in the community appears rare, but the prevalence of antimicrobial-resistant E. coli (including ESBL-producing E. coli) is higher. A high prevalence of antimicrobial-resistant bacteria could have significant health implications for the horse population of the UK. © 2011 EVJ Ltd.

  3. Bacteria with dual resistance to elevated concentrations of heavy metals and antibiotics in Nigerian contaminated systems.

    PubMed

    Oyetibo, Ganiyu O; Ilori, Matthew O; Adebusoye, Sunday Adekunle; Obayori, Oluwafemi S; Amund, Olukayode O

    2010-09-01

    Samples of soil, water, and sediments from industrial estates in Lagos were collected and analyzed for heavy metals and physicochemical composition. Bacteria that are resistant to elevated concentrations of metals (Cd(2+), Co(2+), Ni(2+), Cr(6+), and Hg(2+)) were isolated from the samples, and they were further screened for antibiotic sensitivity. The minimum tolerance concentrations (MTCs) of the isolates with dual resistance to the metals were determined. The physicochemistry of all the samples indicated were heavily polluted. Twenty-two of the 270 bacterial strains isolated showed dual resistances to antibiotics and heavy metals. The MTCs of isolates to the metals were 14 mM for Cd(2+), 15 mM for Co(2+) and Ni(2+), 17 mM for Cr(6+), and 10 mM for Hg(2+). Five strains (Pseudomonas aeruginosa, Actinomyces turicensis, Acinetobacter junni, Nocardia sp., and Micrococcus sp.) resisted all the 18 antibiotics tested. Whereas Rhodococcus sp. and Micrococcus sp. resisted 15 mM Ni(2+), P. aeruginosa resisted 10 mM Co(2+). To our knowledge, there has not been any report of bacterial strains resisting such high doses of metals coupled with wide range of antibiotics. Therefore, dual expressions of antibiotics and heavy-metal resistance make the isolates, potential seeds for decommissioning of sites polluted with industrial effluents rich in heavy metals, since the bacteria will be able to withstand in situ antibiosis that may prevail in such ecosystems.

  4. Efflux pump induction by quaternary ammonium compounds and fluoroquinolone resistance in bacteria.

    PubMed

    Buffet-Bataillon, Sylvie; Tattevin, Pierre; Maillard, Jean-Yves; Bonnaure-Mallet, Martine; Jolivet-Gougeon, Anne

    2016-01-01

    Biocides, primarily those containing quaternary ammonium compounds (QAC), are heavily used in hospital environments and various industries (e.g., food, water, cosmetic). To date, little attention has been paid to potential implications of QAC use in the emergence of antibiotic resistance, especially fluoroquinolone-resistant bacteria in patients and in the environment. QAC-induced overexpression of efflux pumps can lead to: cross resistance with fluoroquinolones mediated by multidrug efflux pumps; stress response facilitating mutation in the Quinolone Resistance Determining Region; and biofilm formation increasing the risk of transfer of mobile genetic elements carrying fluoroquinolone or QAC resistance determinants. By following the European Biocidal Product Regulation, manufacturers of QAC are required to ensure that their QAC-based biocidal products are safe and will not contribute to emerging bacterial resistance.

  5. Agricultural use of antibiotics and the evolution and transfer of antibiotic-resistant bacteria

    PubMed Central

    Khachatourians, G G

    1998-01-01

    Microbial Resistance to antibiotics is on the rise, in part because of inappropriate use of antibiotics in human medicine but also because of practices in the agricultural industry. Intensive animal production involves giving livestock animals large quantities of antibiotics to promote growth and prevent infection. These uses promote the selection of antibiotic resistance in bacterial populations. The resistant bacteria from agricultural environments may be transmitted to humans, in whom they cause disease that cannot be treated by conventional antibiotics. The author reviews trends in antibiotic use in animal husbandry and agriculture in general. The development of resistance is described, along with the genetic mechanisms that create resistance and facilitate its spread among bacterial species. Particular aspects of resistance in bacterial species common to both the human population and the agrifood industry are emphasized. Control measures that might reverse the current trends are highlighted. PMID:9835883

  6. Agricultural use of antibiotics and the evolution and transfer of antibiotic-resistant bacteria.

    PubMed

    Khachatourians, G G

    1998-11-03

    Microbial Resistance to antibiotics is on the rise, in part because of inappropriate use of antibiotics in human medicine but also because of practices in the agricultural industry. Intensive animal production involves giving livestock animals large quantities of antibiotics to promote growth and prevent infection. These uses promote the selection of antibiotic resistance in bacterial populations. The resistant bacteria from agricultural environments may be transmitted to humans, in whom they cause disease that cannot be treated by conventional antibiotics. The author reviews trends in antibiotic use in animal husbandry and agriculture in general. The development of resistance is described, along with the genetic mechanisms that create resistance and facilitate its spread among bacterial species. Particular aspects of resistance in bacterial species common to both the human population and the agrifood industry are emphasized. Control measures that might reverse the current trends are highlighted.

  7. Enteric dysbiosis promotes antibiotic-resistant bacterial infection: systemic dissemination of resistant and commensal bacteria through epithelial transcytosis

    PubMed Central

    Yu, Linda Chia-Hui; Shih, Yi-An; Wu, Li-Ling; Lin, Yang-Ding; Kuo, Wei-Ting; Peng, Wei-Hao; Lu, Kuo-Shyan; Wei, Shu-Chen; Turner, Jerrold R.

    2014-01-01

    Antibiotic usage promotes intestinal colonization of antibiotic-resistant bacteria. However, whether resistant bacteria gain dominance in enteric microflora or disseminate to extraintestinal viscera remains unclear. Our aim was to investigate temporal diversity changes in microbiota and transepithelial routes of bacterial translocation after antibiotic-resistant enterobacterial colonization. Mice drinking water with or without antibiotics were intragastrically gavaged with ampicillin-resistant (Amp-r) nonpathogenic Escherichia coli (E. coli) and given normal water afterward. The composition and spatial distribution of intestinal bacteria were evaluated using 16S rDNA sequencing and fluorescence in situ hybridization. Bacterial endocytosis in epithelial cells was examined using gentamicin resistance assay and transmission electromicroscopy. Paracellular permeability was assessed by tight junctional immunostaining and measured by tissue conductance and luminal-to-serosal dextran fluxes. Our results showed that antibiotic treatment enabled intestinal colonization and transient dominance of orally acquired Amp-r E. coli in mice. The colonized Amp-r E. coli peaked on day 3 postinoculation and was competed out after 1 wk, as evidenced by the recovery of commensals, such as Escherichia, Bacteroides, Lachnospiraceae, Clostridium, and Lactobacillus. Mucosal penetration and extraintestinal dissemination of exogenous and endogenous enterobacteria were correlated with abnormal epithelial transcytosis but uncoupled with paracellular tight junctional damage. In conclusion, antibiotic-induced enteric dysbiosis predisposes to exogenous infection and causes systemic dissemination of both antibiotic-resistant and commensal enterobacteria through transcytotic routes across epithelial layers. These results may help explain the susceptibility to sepsis in antibiotic-resistant enteric bacterial infection. PMID:25059827

  8. Enteric dysbiosis promotes antibiotic-resistant bacterial infection: systemic dissemination of resistant and commensal bacteria through epithelial transcytosis.

    PubMed

    Yu, Linda Chia-Hui; Shih, Yi-An; Wu, Li-Ling; Lin, Yang-Ding; Kuo, Wei-Ting; Peng, Wei-Hao; Lu, Kuo-Shyan; Wei, Shu-Chen; Turner, Jerrold R; Ni, Yen-Hsuan

    2014-10-15

    Antibiotic usage promotes intestinal colonization of antibiotic-resistant bacteria. However, whether resistant bacteria gain dominance in enteric microflora or disseminate to extraintestinal viscera remains unclear. Our aim was to investigate temporal diversity changes in microbiota and transepithelial routes of bacterial translocation after antibiotic-resistant enterobacterial colonization. Mice drinking water with or without antibiotics were intragastrically gavaged with ampicillin-resistant (Amp-r) nonpathogenic Escherichia coli (E. coli) and given normal water afterward. The composition and spatial distribution of intestinal bacteria were evaluated using 16S rDNA sequencing and fluorescence in situ hybridization. Bacterial endocytosis in epithelial cells was examined using gentamicin resistance assay and transmission electromicroscopy. Paracellular permeability was assessed by tight junctional immunostaining and measured by tissue conductance and luminal-to-serosal dextran fluxes. Our results showed that antibiotic treatment enabled intestinal colonization and transient dominance of orally acquired Amp-r E. coli in mice. The colonized Amp-r E. coli peaked on day 3 postinoculation and was competed out after 1 wk, as evidenced by the recovery of commensals, such as Escherichia, Bacteroides, Lachnospiraceae, Clostridium, and Lactobacillus. Mucosal penetration and extraintestinal dissemination of exogenous and endogenous enterobacteria were correlated with abnormal epithelial transcytosis but uncoupled with paracellular tight junctional damage. In conclusion, antibiotic-induced enteric dysbiosis predisposes to exogenous infection and causes systemic dissemination of both antibiotic-resistant and commensal enterobacteria through transcytotic routes across epithelial layers. These results may help explain the susceptibility to sepsis in antibiotic-resistant enteric bacterial infection. Copyright © 2014 the American Physiological Society.

  9. Sulfonamide-Resistant Bacteria and Their Resistance Genes in Soils Fertilized with Manures from Jiangsu Province, Southeastern China

    PubMed Central

    Jiao, Shaojun; Zhang, Jun; Ye, Boping; Gao, Shixiang

    2014-01-01

    Antibiotic-resistant bacteria and genes are recognized as new environmental pollutants that warrant special concern. There were few reports on veterinary antibiotic-resistant bacteria and genes in China. This work systematically analyzed the prevalence and distribution of sulfonamide resistance genes in soils from the environments around poultry and livestock farms in Jiangsu Province, Southeastern China. The results showed that the animal manure application made the spread and abundance of antibiotic resistance genes (ARGs) increasingly in the soil. The frequency of sulfonamide resistance genes was sul1 > sul2 > sul3 in pig-manured soil DNA and sul2 > sul1 > sul3 in chicken-manured soil DNA. Further analysis suggested that the frequency distribution of the sul genes in the genomic DNA and plasmids of the SR isolates from manured soil was sul2 > sul1 > sul3 overall (p<0.05). The combination of sul1 and sul2 was the most frequent, and the co-existence of sul1 and sul3 was not found either in the genomic DNA or plasmids. The sample type, animal type and sampling time can influence the prevalence and distribution pattern of sulfonamide resistance genes. The present study also indicated that Bacillus, Pseudomonas and Shigella were the most prevalent sul-positive genera in the soil, suggesting a potential human health risk. The above results could be important in the evaluation of antibiotic-resistant bacteria and genes from manure as sources of agricultural soil pollution; the results also demonstrate the necessity and urgency of the regulation and supervision of veterinary antibiotics in China. PMID:25405870

  10. Culture-independent detection of "TM7" bacteria in a streptomycin-resistant acidophilic nitrifying process

    NASA Astrophysics Data System (ADS)

    Kurogi, T.; Linh, N. T. T.; Kuroki, T.; Yamada, T.; Hiraishi, A.

    2014-02-01

    Nitrification in biological wastewater treatment processes has been believed for long time to take place under neutral conditions and is inhibited under acidic conditions. However, we previously constructed acidophilic nitrifying sequencing-batch reactors (ANSBRs) being capable of nitrification at < pH 4 and harboring bacteria of the candidate phylum "TM7" as the major constituents of the microbial community. In light of the fact that the 16S rRNA of TM7 bacteria has a highly atypical base substitution possibly responsible for resistance to streptomycin at the ribosome level, this study was undertaken to construct streptomycin-resistant acidophilic nitrifying (SRAN) reactors and to demonstrate whether TM7 bacteria are abundant in these reactors. The SRAN reactors were constructed by seeding with nitrifying sludge from an ANSBR and cultivating with ammonium-containing mineral medium (pH 4.0), to which streptomycin at a concentration of 10, 30 and 50 mg L-1 was added. In all reactors, the pH varied between 2.7 and 4.0, and ammonium was completely converted to nitrate in every batch cycle. PCR-aided denaturing gradient gel electrophoresis (DGGE) targeting 16S rRNA genes revealed that some major clones assigned to TM7 bacteria and Gammaproteobacteria were constantly present during the overall period of operation. Fluorescence in situ hybridization (FISH) with specific oligonucleotide probes also showed that TM7 bacteria predominated in all SRAN reactors, accounting for 58% of the total bacterial population on average. Although the biological significance of the TM7 bacteria in the SRAN reactors are unknown, our results suggest that these bacteria are possibly streptomycin-resistant and play some important roles in the acidophilic nitrifying process.

  11. Culture-independent detection of 'TM7' bacteria in a streptomycin-resistant acidophilic nitrifying process

    SciTech Connect

    Kurogi, T.; Linh, N. T. T.; Kuroki, T.; Yamada, T.; Hiraishi, A.

    2014-02-20

    Nitrification in biological wastewater treatment processes has been believed for long time to take place under neutral conditions and is inhibited under acidic conditions. However, we previously constructed acidophilic nitrifying sequencing-batch reactors (ANSBRs) being capable of nitrification at < pH 4 and harboring bacteria of the candidate phylum 'TM7' as the major constituents of the microbial community. In light of the fact that the 16S rRNA of TM7 bacteria has a highly atypical base substitution possibly responsible for resistance to streptomycin at the ribosome level, this study was undertaken to construct streptomycin-resistant acidophilic nitrifying (SRAN) reactors and to demonstrate whether TM7 bacteria are abundant in these reactors. The SRAN reactors were constructed by seeding with nitrifying sludge from an ANSBR and cultivating with ammonium-containing mineral medium (pH 4.0), to which streptomycin at a concentration of 10, 30 and 50 mg L{sup −1} was added. In all reactors, the pH varied between 2.7 and 4.0, and ammonium was completely converted to nitrate in every batch cycle. PCR-aided denaturing gradient gel electrophoresis (DGGE) targeting 16S rRNA genes revealed that some major clones assigned to TM7 bacteria and Gammaproteobacteria were constantly present during the overall period of operation. Fluorescence in situ hybridization (FISH) with specific oligonucleotide probes also showed that TM7 bacteria predominated in all SRAN reactors, accounting for 58% of the total bacterial population on average. Although the biological significance of the TM7 bacteria in the SRAN reactors are unknown, our results suggest that these bacteria are possibly streptomycin-resistant and play some important roles in the acidophilic nitrifying process.

  12. Preparation of silver nanoparticles fabrics against multidrug-resistant bacteria

    NASA Astrophysics Data System (ADS)

    Hanh, Truong Thi; Thu, Nguyen Thi; Hien, Nguyen Quoc; An, Pham Ngoc; Loan, Truong Thi Kieu; Hoa, Phan Thi

    2016-04-01

    The silver nanoparticles (AgNPs)/peco fabrics were prepared by immobilization of AgNPs on fabrics in which AgNPs were synthesized by γ-irradiation of the 10 mM AgNO3 chitosan solution at the dose of 17.6 kGy. The AgNPs size has been estimated to be about 11 nm from TEM image. The AgNPs content onto peco fabrics was of 143±6 mg/kg at the initial AgNPs concentration of 100 ppm. The AgNPs colloidal solution was characterized by UV-vis spectroscopy and TEM image. The antibacterial activity of AgNPs/peco fabrics after 60 washings against Staphylococcus aureus and Klebsiella pneumoniae was found to be over 99%. Effects of AgNPs fabics on multidrug-resistant pathogens from the clinical specimens were also tested.

  13. Intestinal regeneration as an insect resistance mechanism to entomopathogenic bacteria

    PubMed Central

    Castagnola, Anaïs; Jurat-Fuentes, Juan Luis

    2016-01-01

    The intestinal epithelium of insects is exposed to xenobiotics and entomopathogens during the feeding developmental stages. In these conditions, an effective enterocyte turnover mechanism is highly desirable to maintain integrity of the gut epithelial wall. As in other insects, the gut of lepidopteran larvae have stem cells that are capable of proliferation, which occurs during molting and pathogenic episodes. While much is known on the regulation of gut stem cell division during molting, there is a current knowledge gap on the molecular regulation of gut healing processes after entomopathogen exposure. Relevant information on this subject is emerging from studies of the response to exposure to insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) as model intoxicants. In this work we discuss currently available data on the molecular cues involved in gut stem cell proliferation, insect gut healing, and the implications of enhanced healing as a potential mechanism of resistance against Bt toxins. PMID:27436739

  14. Efficacy of Locally Isolated Lactic Acid Bacteria Against Antibiotic-Resistant Uropathogens.

    PubMed

    Manzoor, Asma; Ul-Haq, Ikram; Baig, Shahjhan; Qazi, Javed Iqbal; Seratlic, Sanja

    2016-01-01

    Antibiotic resistance represents a serious global health threat to public health, so infections such as pneumonia and urinary tract infection (UTI) are becoming harder to treat. Therefore, it is necessary to develop an action plan to restrain the problem of antibiotic resistance. One approach in UTI control could be the use of lactobacilli because these indigenous inhabitants in human intestine have been found to play an important role in protecting the host from various infections. We sought to check the efficacy of locally isolated Lactobacillus species to eradicate antibiotic-resistant pathogenic bacteria causing UTI. Lactic acid bacteria isolated from spoiled fruits and vegetables and grown in MRS medium were screened against multi-drug-resistant Candida albicans, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus fecalis. Fifty-four lactic acid bacteria were isolated from spoiled fruits and vegetables, of which 11 Gram-positive and catalase-negative Lactobacillus isolates were identified by carbohydrate assimilation profiles as Lactobacillus acidophilus, L. paracasei, L. delbrueckii, L. casei, L. helveticus, L. brevis, L. salivarius, L. fermentum, L. rhamnosus, L. animalis, and L. plantarum. The latter organism had the highest abundance of all the samples, so its isolates were also verified through 16S rRNA gene sequencing. The isolated Lactobacilli were screened against multi-drug-resistant uropathogens, viz. C. albicans, P. aeruginosa, K. pneumoniae, E. fecalis, and E. coli. The growth inhibition zone (GIZ) was over 10 mm against all the uropathogenic test organisms, where L. fermentum and L. plantarum strains demonstrated remarkable inhibitory activities against E. coli and E. faecalis, with a GIZ up to 28 mm. The susceptibility test to 16 antibiotics showed multidrug resistance (3 to 5 antibiotics) among all the tested uropathogens. The obtained results revealed that all the Lactobacillus isolates displayed antimicrobial

  15. Efficacy of Locally Isolated Lactic Acid Bacteria Against Antibiotic-Resistant Uropathogens

    PubMed Central

    Manzoor, Asma; Ul-Haq, Ikram; Baig, Shahjhan; Qazi, Javed Iqbal; Seratlic, Sanja

    2016-01-01

    Background: Antibiotic resistance represents a serious global health threat to public health, so infections such as pneumonia and urinary tract infection (UTI) are becoming harder to treat. Therefore, it is necessary to develop an action plan to restrain the problem of antibiotic resistance. One approach in UTI control could be the use of lactobacilli because these indigenous inhabitants in human intestine have been found to play an important role in protecting the host from various infections. Objectives: We sought to check the efficacy of locally isolated Lactobacillus species to eradicate antibiotic-resistant pathogenic bacteria causing UTI. Materials and Methods: Lactic acid bacteria isolated from spoiled fruits and vegetables and grown in MRS medium were screened against multi-drug-resistant Candida albicans, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus fecalis. Results: Fifty-four lactic acid bacteria were isolated from spoiled fruits and vegetables, of which 11 Gram-positive and catalase-negative Lactobacillus isolates were identified by carbohydrate assimilation profiles as Lactobacillus acidophilus, L. paracasei, L. delbrueckii, L. casei, L. helveticus, L. brevis, L. salivarius, L. fermentum, L. rhamnosus, L. animalis, and L. plantarum. The latter organism had the highest abundance of all the samples, so its isolates were also verified through 16S rRNA gene sequencing. The isolated Lactobacilli were screened against multi-drug-resistant uropathogens, viz. C. albicans, P. aeruginosa, K. pneumoniae, E. fecalis, and E. coli. The growth inhibition zone (GIZ) was over 10 mm against all the uropathogenic test organisms, where L. fermentum and L. plantarum strains demonstrated remarkable inhibitory activities against E. coli and E. faecalis, with a GIZ up to 28 mm. The susceptibility test to 16 antibiotics showed multidrug resistance (3 to 5 antibiotics) among all the tested uropathogens. Conclusions: The obtained results

  16. Bisphosphocins: novel antimicrobials for enhanced killing of drug-resistant and biofilm-forming bacteria.

    PubMed

    Wong, Jonathan P; DiTullio, Paul; Parkinson, Steve

    2015-01-01

    The global prevalence of antibiotic resistance and the threat posed by drug-resistant superbugs are a leading challenge confronting modern medicine in the 21st century. However, the progress on the development of novel antibiotics to combat this problem is severely lagging. A more concerted effort to develop novel therapeutic agents with robust activity and unique mechanisms of action will be needed to overcome the problem of drug resistance. Furthermore, biofilm forming bacteria are known to be increasingly resistant to the actions of antibiotics and are a leading cause of mortality or morbidity in nosocomial infections. Bisphosphocins (also scientifically known as nubiotics) are novel small protonated deoxynucleotide molecules, and exert their antibacterial activity by depolarization of the bacterial cell membrane, causing bacterial cell death. Bisphosphocins may represent an effective weapon against antibiotic-resistant and biofilm-forming pathogenic bacteria. Preclinical efficacy studies in animals have shown that the compounds are safe and, efficacious against various bacterial infections, including drug-resistant pathogens. In vitro biochemical analysis confirmed that the bactericidal activity of bisphosphocins is mediated by depolarization of the bacterial cell membrane, and these compounds are better able to penetrate through bacterial biofilm and kill the biofilm encased bacteria. This article will cover the structure, mode of action, safety, efficacy and the current state of development of bisphosphocins. Together, the information presented here will present a strong case for bisphosphocins to be considered for use as new weapons to complement the existing arsenal of antimicrobial drugs and as a first line defence against drug-resistant and biofilm-forming bacteria.

  17. Ciprofloxacin residue and antibiotic-resistant biofilm bacteria in hospital effluent.

    PubMed

    Ory, Jérôme; Bricheux, Geneviève; Togola, Anne; Bonnet, Jean Louis; Donnadieu-Bernard, Florence; Nakusi, Laurence; Forestier, Christiane; Traore, Ousmane

    2016-07-01

    Discharge of antimicrobial residues and resistant bacteria in hospital effluents is supposed to have strong impacts on the spread of antibiotic resistant bacteria in the environment. This study aimed to characterize the effluents of the Gabriel Montpied teaching hospital, Clermont-Ferrand, France, by simultaneously measuring the concentration of ciprofloxacin and of biological indicators resistant to this molecule in biofilms formed in the hospital effluent and by comparing these data to ciprofloxacin consumption and resistant bacterial isolates of the hospital. Determination of the measured environmental concentration of ciprofloxacin by spot sampling and polar organic chemical integrative (POCIS) sampling over 2 weeks, and comparison with predicted environmental concentrations produced a hazard quotient >1, indicating a potential ecotoxicological risk. A negative impact was also observed with whole hospital effluent samples using the Tetrahymena pyriformis biological model. During the same period, biofilms were formed within the hospital effluent, and analysis of ciprofloxacin-resistant isolates indicated that Gamma-Proteobacteria were numerous, predominantly Aeromonadaceae (69.56%) and Enterobacteriaceae (22.61%). Among the 115 isolates collected, plasmid-mediated fluoroquinolone-resistant genes were detected, with mostly aac(6')-lb-cr and qnrS. In addition, 60% of the isolates were resistant to up to six antibiotics, including molecules mostly used in the hospital (aminosides and third-generation cephalosporins). In parallel, 1247 bacteria isolated from hospitalized patients and resistant to at least one of the fluoroquinolones were collected. Only 5 of the 14 species identified in the effluent biofilm were also found in the clinical isolates, but PFGE typing of the Gram-negative isolates found in both compartments showed there was no clonality among the strains. Altogether, these data confirm the role of hospital loads as sources of pollution for wastewater

  18. [Correlations of integrons and resistance gene cassettes in Gram-negative bacteria with multi-drug resistance].

    PubMed

    Li, Jiao; Ma, Yun-xia; Zhang, Quan-bin; Zhou, Yong-an; Shang, Run-ping; Li, Peng-li; Hao, Zi-qi

    2013-12-01

    To explore the correlations of integrons, gene cassettes and drug resistance phenotypes in 90 multi-drug resistant Gram-negative bacteria. Class I/II/III integron and variable region of positive strains of 90 Gram-negative bacteria were amplified by PCR and types of integron variable region gene cassettes analyzed by DNA sequence. And the resistant rates of integron positive and negative strains were tested by drug susceptibility. The detection rate of integron was 81.1% (73/90) in 90 Gram-negative bacteria. The integron types were class I (n = 70), class II (n = 3) and class III (n = 0). Based on the BLAST analysis by GenBank database, in the amplified fragments of Class I integron positive strains variable region gene ranging from 730 to 3300 bp, 8 types of integron structure were identified. And there were aadB (n = 11), aac (6')-II (n = 7), aadA5 (n = 10), dfrA17-aadA5 (n = 14), dfrA12-OrfF-aadA2(n = 1), aacA4-catB8-aadA1(n = 24), aacC1-OrfA-OrfB-aadA1 (n = 3), catB3-aadB-dhfrV-aacA4-nit1-nit2 (n = 1), in which catB3-aadB-dhfrV-aacA4-nit1-nit2 was a new resistance gene cassette; the variable region fragment of class II integron positive strain was 1600 bp, with 3 carrier strains of sat2-aadA1 gene cassette.Susceptibility testing showed that the antimicrobial resistance rate of integron positive strains to aminoglycosides and sulfa were significantly higher than those of integron negative strains and accorded with the results of integration variable region gene cassettes; the positive strains were more sensitive to amikacin with a resistance rate of 32.9% (24/73); and the drug resistance rates of all beta-lactam strains were ≥ 80%. There is a higher carrier rates of classI integron in Gram-negative bacteria. And the resistant phenotype is related with the types of resistance gene cassettes of integron variable region.

  19. Prevalence of plasmid-mediated multidrug resistance determinants in fluoroquinolone-resistant bacteria isolated from sewage and surface water.

    PubMed

    Osińska, Adriana; Harnisz, Monika; Korzeniewska, Ewa

    2016-06-01

    Fluoroquinolones (FQs) are fully synthetic broad-spectrum antibacterial agents that are becoming increasingly popular in the treatment of clinical and veterinary infections. Being excreted during treatment, mostly as active compounds, their biological action is not limited to the therapeutic site, but it is moved further as resistance selection pressure into the environment. Water environment is an ideal medium for the aggregation and dissemination of antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs), which can pose a serious threat to human health. Because of this, the aim of this study was to determine the number of fluoroquinolone-resistant bacteria (FQRB) and their share in total heterotrophic plate counts (HPC) in treated wastewater (TWW), and upstream and downstream river water (URW, DRW) samples where TWW is discharged. The spread of plasmid-mediated quinolone resistance (PMQR) determinants and the presence/absence of resistance genes to other most popular antibiotic groups (against tetracyclines and beta-lactams) in selected 116 multiresistant isolates were investigated. The share of FQRB in total HPC in all samples was rather small and ranged from 0.7 % in URW samples to 7.5 % in TWW. Bacteria from Escherichia (25.0 %), Acinetobacter (25.0 %), and Aeromonas (6.9 %) genera were predominant in the FQRB group. Fluoroquinolone resistance was mostly caused by the presence of the gene aac(6')-1b-cr (91.4 %). More rarely reported was the occurrence of qnrS, qnrD, as well as oqxA, but qnrA, qnrB, qepA, and oqxB were extremely rarely or never noted in FQRB. The most prevalent bacterial genes connected with beta-lactams' resistance in FQRB were bla TEM, bla OXA, and bla CTX-M. The bla SHV was less common in the community of FQRB. The occurrence of bla genes was reported in almost 29.3 % of FQRB. The most abundant tet genes in FQRB were tet(A), tet(L), tet(K), and tet(S). The prevalence of tet genes was observed in 41.4

  20. Re-sensitizing drug-resistant bacteria to antibiotics by designing Antisense Therapeutics

    NASA Astrophysics Data System (ADS)

    Courtney, Colleen; Chatterjee, Anushree

    2014-03-01

    ``Super-bugs'' or ``multi-drug resistant organisms'' are a serious international health problem, with devastating consequences to patient health care. The Center for Disease Control has identified antibiotic resistance as one of the world's most pressing public health problems as a significant fraction of bacterial infections contracted are drug resistant. Typically, antibiotic resistance is encoded by ``resistance-genes'' which express proteins that carryout the resistance causing functions inside the bacterium. We present a RNA based therapeutic strategy for designing antimicrobials capable of re-sensitizing resistant bacteria to antibiotics by targeting labile regions of messenger RNAs encoding for resistance-causing proteins. We perform in silico RNA secondary structure modeling to identify labile target regions in an mRNA of interest. A synthetic biology approach is then used to administer antisense nucleic acids to our model system of ampicillin resistant Escherichia coli. Our results show a prolonged lag phase and decrease in viability of drug-resistant E. colitreated with antisense molecules. The antisense strategy can be applied to alter expression of other genes in antibiotic resistance pathways or other pathways of interest.

  1. Antibiotic resistance among aquatic bacteria in natural freshwater environments of Korea.

    PubMed

    Kim, Tae Woon; Joung, Yochan; Han, Ji-Hye; Jung, Wonwha; Kim, Seung Bum

    2015-12-01

    The taxonomic diversity and antibiotic resistance among freshwater bacterial communities in the major water bodies of Korea was examined using 437 penicillin-resistant, and 110 tetracycline-resistant bacterial isolates. Based on 16S rRNA gene sequence analysis, most isolates were assigned to Proteobacteria, which was then followed by Bacteroidetes. Strains of Aeromonas were found as the most abundant penicillin-resistant populations, whereas those affiliated to diverse species including enteric groups were found as the most abundant tetracycline-resistant populations. Most strains exhibited multiple antibiotic resistance, and all tested strains were resistant to penicillin and hygromycin. High levels of resistance were observed for antibiotics acting on cell wall synthesis, whereas low levels were for those acting on DNA replication or transcription in general. It is apparent from this study that penicillin resistance is widespread among environmental bacteria, although the antibiotic has been generally non-detectable in the environment. It is also likely from the taxonomic composition of the resistant communities that various sources including terrestrial animals and humans may contribute to antibiotic resistance in the freshwater environment.

  2. Intervention to Reduce Transmission of Resistant Bacteria in Intensive Care

    PubMed Central

    Huskins, W. Charles; Huckabee, Charmaine M.; O’Grady, Naomi P.; Murray, Patrick; Kopetskie, Heather; Zimmer, Louise; Walker, Mary Ellen; Sinkowitz-Cochran, Ronda L.; Jernigan, John A.; Samore, Matthew; Wallace, Dennis; Goldmann, Donald A.

    2012-01-01

    BACKGROUND Intensive care units (ICUs) are high-risk settings for the transmission of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE). METHODS In a cluster-randomized trial, we evaluated the effect of surveillance for MRSA and VRE colonization and of the expanded use of barrier precautions (intervention) as compared with existing practice (control) on the incidence of MRSA or VRE colonization or infection in adult ICUs. Surveillance cultures were obtained from patients in all participating ICUs; the results were reported only to ICUs assigned to the intervention. In intervention ICUs, patients who were colonized or infected with MRSA or VRE were assigned to care with contact precautions; all the other patients were assigned to care with universal gloving until their discharge or until surveillance cultures obtained at admission were reported to be negative. RESULTS During a 6-month intervention period, there were 5434 admissions to 10 intervention ICUs, and 3705 admissions to 8 control ICUs. Patients who were colonized or infected with MRSA or VRE were assigned to barrier precautions more frequently in intervention ICUs than in control ICUs (a median of 92% of ICU days with either contact precautions or universal gloving [51% with contact precautions and 43% with universal gloving] in intervention ICUs vs. a median of 38% of ICU days with contact precautions in control ICUs, P<0.001). In intervention ICUs, health care providers used clean gloves, gowns, and hand hygiene less frequently than required for contacts with patients assigned to barrier precautions; when contact precautions were specified, gloves were used for a median of 82% of contacts, gowns for 77% of contacts, and hand hygiene after 69% of contacts, and when universal gloving was specified, gloves were used for a median of 72% of contacts and hand hygiene after 62% of contacts. The mean (±SE) ICU-level incidence of events of colonization or infection

  3. How innate immunity proteins kill bacteria and why they are not prone to resistance.

    PubMed

    Dziarski, Roman; Gupta, Dipika

    2017-08-24

    Recent advances on antibacterial activity of peptidoglycan recognition proteins (PGRPs) offer some insight into how innate immunity has retained its antimicrobial effectiveness for millions of years with no frequent emergence of resistant strains. First, PGRP can bind to multiple components of bacterial envelope (peptidoglycan, lipoteichoic acid, and lipopolysaccharide). Second, PGRP simultaneously induces oxidative, thiol, and metal stress responses in bacteria, which individually are bacteriostatic, but in combination are bactericidal. Third, PGRP induces oxidative, thiol, and metal stress responses in bacteria through three independent pathways. Fourth, antibacterial effects of PGRP are enhanced by other innate immune responses. Thus, emergence of PGRP resistance is prevented by bacteriostatic effect and independence of each PGRP-induced stress response, as PGRP resistance would require simultaneous acquisition of three separate mechanisms disabling the induction of all three stress responses. By contrast, each antibiotic has one primary target and one primary antibacterial mechanism, and for this reason resistance to antibiotics can be generated by inhibition of this primary mechanism. Manipulating bacterial metabolic responses can enhance bacterial killing by antibiotics and elimination of antibiotic-tolerant bacteria, but such manipulations do not overcome genetically encoded antibiotic resistance. Pathogens cause infections by evading, inhibiting, or subverting host immune responses.

  4. Lufenuron suppresses the resistance of Formosan subterranean termites (Isoptera: Rhinotermitidae) to entomopathogenic bacteria.

    PubMed

    Wang, Cai; Henderson, Gregg; Gautam, Bal K

    2013-08-01

    Pesticides can negatively affect insect immunity. Although studies show that Formosan subterranean termites, Coptotermes formosanus Shiraki, are resistant to microbial infections, the effects of pesticides on disease resistance is not well studied. In this study, C. formosanus previously fed lufenuron was exposed to each of the three entomopathogenic bacteria, Pseudomonas aeruginosa (Schroeter) Migula, Serratia marcescens Bizio, and Bacillus thuringiensis Berliner subsp. israelensis. We found that termite mortality was significantly higher and synergistic in the combination of lufenuron and P. aeruginosa compared with treatment of lufenuron or P. aeruginosa alone. Other bacteria and lufenuron combinations were not quite as effective. Interestingly, only in treatments without lufenuron did termites show carcass-burying behavior. The results indicate that lufenuron, a chitin synthesis inhibitor, can suppress Formosan subterranean termite resistance to P. aeruginosa. Possible suppression mechanisms are discussed.

  5. Infections Caused by Resistant Gram-Negative Bacteria: Epidemiology and Management.

    PubMed

    Kaye, Keith S; Pogue, Jason M

    2015-10-01

    Infections caused by resistant gram-negative bacteria are becoming increasingly prevalent and now constitute a serious threat to public health worldwide because they are difficult to treat and are associated with high morbidity and mortality rates. In the United States, there has been a steady increase since 2000 in rates of extended-spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and multidrug-resistant strains of Pseudomonas aeruginosa and Acinetobacter baumannii, particularly among hospitalized patients with intraabdominal infections, urinary tract infections, ventilator-associated pneumonia, and bacteremia. Colonization with resistant gram-negative bacteria is common among residents in long-term care facilities (particularly those residents with an indwelling device), and these facilities are considered important originating sources of such strains for hospitals. Antibiotic resistance is associated with a substantial clinical and economic burden, including increased mortality, greater hospital and antibiotic costs, and longer stays in hospitals and intensive care units. Control of resistant gram-negative infections requires a comprehensive approach, including strategies for risk factor identification, detection and identification of resistant organisms, and implementation of infection-control and prevention strategies. In treating resistant gram-negative infections, a review of surveillance data and hospital-specific antibiograms, including resistance patterns within local institutions, and consideration of patient characteristics are helpful in guiding the choice of empiric therapy. Although only a few agents are available with activity against resistant gram-negative organisms, two recently released β-lactam/β-lactamase inhibitor combinations - ceftolozane/tazobactam and ceftazidime/avibactam - have promising activity against these organisms. In this article, we review the epidemiology, risk factors, and

  6. Isolation and Characterization of Bacteria Resistant to Metallic Copper Surfaces▿ †

    PubMed Central

    Espírito Santo, Christophe; Morais, Paula Vasconcelos; Grass, Gregor

    2010-01-01

    Metallic copper alloys have recently attracted attention as a new antimicrobial weapon for areas where surface hygiene is paramount. Currently it is not understood on a molecular level how metallic copper kills microbes, but previous studies have demonstrated that a wide variety of bacteria, including Escherichia coli, Staphylococcus aureus, and Clostridium difficile, are inactivated within minutes or a few hours of exposure. In this study, we show that bacteria isolated from copper alloy coins comprise strains that are especially resistant against the toxic properties exerted by dry metallic copper surfaces. The most resistant of 294 isolates were Gram-positive staphylococci and micrococci, Kocuria palustris, and Brachybacterium conglomeratum but also included the proteobacterial species Sphingomonas panni and Pseudomonas oleovorans. Cells of some of these bacterial strains survived on copper surfaces for 48 h or more. Remarkably, when these dry-surface-resistant strains were exposed to moist copper surfaces, resistance levels were close to those of control strains and MICs for copper ions were at or below control strain levels. This suggests that mechanisms conferring resistance against dry metallic copper surfaces in these newly isolated bacterial strains are different from well-characterized copper ion detoxification systems. Furthermore, staphylococci on coins did not exhibit increased levels of resistance to antibiotics, arguing against coselection with copper surface resistance traits. PMID:20048058

  7. Glycopeptide antibiotic analogs efficient against vancomycin-resistant bacteria: a patent evaluation (WO2013022763).

    PubMed

    Olsufyeva, Eugenia N; Preobrazhenskaya, Maria N

    2013-12-01

    The patent claims the preparation of vancomycin analogs equally active against bacterial strains that are primarily sensitive or resistant to this antibiotic. The pseudopeptide core of new compounds carries the amidine group that replaces the carboxamide linking group in the D ring-bearing amino acid residue of the glycopeptide. An elegant method of synthesis of amidine containing glycopeptides via thioamides was developed. The key glycopeptide thioamide analogs were prepared by total multistep synthesis. These analogs can be readily converted to the antibiotic's amidine as well as to alkylamidines, amidrazones, hydroxyamidines and similar analogs. The new analogs are capable of circumventing bacterial resistance derived from the D-Ala-D-Ala to D-Ala-D-Lac alteration - the mechanism operational in the resistant strains VanA and VanB. The interaction of the carboxamide, thioamide and amidine fragments of vancomycin analogs with the targets in resistant and sensitive bacteria was investigated. The novel compounds demonstrated potent activity against VanA-resistant bacteria Enterococcus faecalis (minimal inhibitory concentration = 0.3 - 0.6 μg/ml). However data on susceptible strains and resistant clinical isolates are lacking to further document the interest of the compounds. The results provide evidence for structural modifications that can improve the therapeutic efficacy of vancomycin, in particular, for treatment of vancomycin-resistant infections.

  8. Isolation, identification and characterization of highly tellurite-resistant, tellurite-reducing bacteria from Antarctica

    NASA Astrophysics Data System (ADS)

    Arenas, Felipe A.; Pugin, Benoit; Henríquez, Nicole A.; Arenas-Salinas, Mauricio A.; Díaz-Vásquez, Waldo A.; Pozo, María F.; Muñoz, Claudia M.; Chasteen, Thomas G.; Pérez-Donoso, José M.; Vásquez, Claudio C.

    2014-03-01

    The tellurium oxyanion, tellurite, is extremely noxious to most living organisms. Its toxicity has been mainly related to the generation of reactive oxygen species (ROS) as well as to an unbalancing of the thiol:redox buffering system. Nevertheless, a few bacteria are capable of thriving at high tellurite concentrations. One mechanism of resistance is the enzymatic and non-enzymatic reduction of tellurite to the less toxic elemental tellurium. This reduction generates nano- to micrometric tellurium crystals that display different shapes and sizes. To date, a very limited number of highly tellurite-resistant and tellurite-reducing bacterial species are available from international culture collections. In this work, we decided to look for tellurite-reducing bacteria from an extreme environment, Antarctica. This environment exhibits a combination of several extreme factors such as high UV-radiation and desiccation and freezing conditions that impact directly on the local biodiversity. Since, as does, all these factors induce ROS formation, we hypothesized that Antarctic bacteria could also exhibit tellurite-resistance. In this context, we isolated 123 tellurite-resistant bacteria, and characterized six new tellurite-resistant and tellurite-reducing bacterial strains from samples collected in Antarctica. These strains were identified according to their 16S rRNA gene sequence as Staphylococcus hameolyticus, Staphylococcus sciuri, Acinetobacter haemolyticus, Pseudomonas lini, and two strains of Psychrobacter immobilis. The isolates display tellurite-resistance about 35- to 500-fold higher than Escherichia coli (Te-sensitive organism), and a high level of tellurite reduction which might be interesting for an application in the field of bioremediation or nanoparticle biosynthesis.

  9. How Fitness Reduced, Antimicrobial Resistant Bacteria Survive and Spread: A Multiple Pig - Multiple Bacterial Strain Model

    PubMed Central

    Græsbøll, Kaare; Nielsen, Søren Saxmose; Toft, Nils; Christiansen, Lasse Engbo

    2014-01-01

    More than 30% of E. coli strains sampled from pig farms in Denmark over the last five years were resistant to the commonly used antimicrobial tetracycline. This raises a number of questions: How is this high level sustained if resistant bacteria have reduced growth rates? Given that there are multiple susceptible and resistant bacterial strains in the pig intestines, how can we describe their coexistence? To what extent does the composition of these multiple strains in individual pigs influence the total bacterial population of the pig pen? What happens to a complex population when antimicrobials are used? To investigate these questions, we created a model where multiple strains of bacteria coexist in the intestines of pigs sharing a pen, and explored the parameter limits of a stable system; both with and without an antimicrobial treatment. The approach taken is a deterministic bacterial population model with stochastic elements of bacterial distributions and transmission. The rates that govern the model are process-oriented to represent growth, excretion, and uptake from environment, independent of herd and meta-population structures. Furthermore, an entry barrier and elimination process for the individual strains in each pig were implemented. We demonstrate how competitive growth between multiple bacterial strains in individual pigs, and the transmission between pigs in a pen allow for strains of antimicrobial resistant bacteria to persist in a pig population to different extents, and how quickly they can become dominant if antimicrobial treatment is initiated. The level of spread depends in a non-linear way of the parameters that govern excretion and uptake. Furthermore, the sampling of initial distributions of strains and stochastic transmission events give rise to large variation in how homogenous and how resistant the bacterial population becomes. Most important: resistant bacteria are demonstrated to survive with a disadvantage in growth rate of well over 10

  10. Antibiotic resistance of lactic acid bacteria isolated from dry-fermented sausages.

    PubMed

    Fraqueza, Maria João

    2015-11-06

    Dry-fermented sausages are meat products highly valued by many consumers. Manufacturing process involves fermentation driven by natural microbiota or intentionally added starter cultures and further drying. The most relevant fermentative microbiota is lactic acid bacteria (LAB) such as Lactobacillus, Pediococcus and Enterococcus, producing mainly lactate and contributing to product preservation. The great diversity of LAB in dry-fermented sausages is linked to manufacturing practices. Indigenous starters development is considered to be a very promising field, because it allows for high sanitary and sensorial quality of sausage production. LAB have a long history of safe use in fermented food, however, since they are present in human gastrointestinal tract, and are also intentionally added to the diet, concerns have been raised about the antimicrobial resistance in these beneficial bacteria. In fact, the food chain has been recognized as one of the key routes of antimicrobial resistance transmission from animal to human bacterial populations. The World Health Organization 2014 report on global surveillance of antimicrobial resistance reveals that this issue is no longer a future prediction, since evidences establish a link between the antimicrobial drugs use in food-producing animals and the emergence of resistance among common pathogens. This poses a risk to the treatment of nosocomial and community-acquired infections. This review describes the possible sources and transmission routes of antibiotic resistant LAB of dry-fermented sausages, presenting LAB antibiotic resistance profile and related genetic determinants. Whenever LAB are used as starters in dry-fermented sausages processing, safety concerns regarding antimicrobial resistance should be addressed since antibiotic resistant genes could be mobilized and transferred to other bacteria.

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

    PubMed

    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

  12. [Epidemiological features of multidrug resistant bacteria isolated from urine samples at the Mohammed V Military Teaching Hospital in Rabat, Morocco].

    PubMed

    Zohoun, A; Ngoh, E; Bajjou, T; Sekhsokh, Y; Elhamzaoui, S

    2010-08-01

    Hospital-acquired multidrug resistant bacteria infections are a serious public health issue causing increased morbidity, mortality and care cost. These risks underscore the need for health care institutions to maintain active panels to monitor, prevent, and manage hospital-acquired infections. The purpose of this study was to assess the epidemiology of urinary tract infection involving multidrug resistant bacteria at the Microbiology Laboratory of the Mohammed-V Military Teaching Hospital in Rabat. Study was carried out retrospectively on bacteria isolated from 10,243 urinary samples collected from January 1 to December 31, 2008. A total of 1,439 non-redundant bacteria (14.1%) meeting the criteria of urinary infection were identified. One hundred and three of the 1,439 bacteria isolated (7%) were multidrug resistant. Multidrug-resistant bacteria were more common in in-patients (63.1%). Mean patient age was 53.8 +/- 18.2 and the M/F sex ratio was 2.2. The most common multi-drug resistant bacteria were Enterobacteria producing extended spectrum bêta-lactamase (54.4% including 40.8% of Klebsiella pneumonia) and non-fermenting bacteria (45.6% including 26.2% of Pseudomonas aeruginosa. and 19.4% of Acinetobacter baumannii. These bacteria were resistant to the most commonly used antibiotics but remained highly sensitive to colistin, imipenem and amikacin.

  13. Novel ISCR1-linked resistance genes found in multidrug-resistant Gram-negative bacteria in southern China.

    PubMed

    Wang, Fengping; Wu, Kuihai; Sun, Jingjing; Wang, Qian; Chen, Qing; Yu, Shouyi; Rui, Yongyu

    2012-11-01

    Non-duplicate multidrug-resistant (MDR) Gram-negative bacteria (n=1329) isolated from southern China between January 2008 and December 2009 were investigated for the presence of ISCR1 as well as characterisation of ISCR1-linked resistance genes. Of 433 ISCR1-positive strains, 151 appeared to carry ISCR1-linked resistance genes. Seven different ISCR1-linked resistance gene arrays were identified by restriction fragment length polymorphism (RFLP) and DNA sequencing analysis. Many of these arrays are reported in some species for the first time. A total of 12 genes, including a novel ABC transporter (GenBank accession no. GU944725), qnrA1, qnrB2, qnrB6, bla(DHA-1), ampR, bla(CTX-M-9), bla(PER-1), insB, sapA-like peptide transport periplasmic protein, putative glutathione S-transferase and short-chain dehydrogenase/reductase, were detected. This study was the first to employ PCR-RFLP using HinfI and RsaI to analyse ISCR1-linked genes. ISCR1 was widely disseminated among MDR Gram-negative bacteria and was in close association with quinolone resistance and β-lactamase genes (class A and class C) in southern China.

  14. Induced systemic resistance of selected endophytic bacteria against Meloidogyne incognita on tomato.

    PubMed

    Munif, A; Hallmann, J; Sikora, R A

    2001-01-01

    In previous work, the four endophytic bacteria Pantoea agglomerans MK-29, Cedeca davisae MK-30, Enterobacter spp. MK-42 and Pseudomonas putida MT-19 were shown to reduce Meloidogyne incognita on tomato when applied as a seed treatment and/or soil drench. The objective of this work was to study these bacteria for their potential to induce systemic resistance against root knot nematodes on tomato. To guarantee spatial separation between inducing agent and pathogen a split-root system was chosen and inoculated with the bacteria as a drench application on one side of the root system and 6 days later with 2000 juveniles of Meloidogyne incognita on the other side of the split-root system. The experiment was maintained in the greenhouse and repeated once. The penetration rate of juveniles as well as the total number of root-knot galls and egg masses was recorded. Treatment with all four bacteria significantly reduced juvenile penetration and the number of root-knot galls when compared with the non-treated control. Induced systemic resistance is considered a possible control mechanism of endophytic bacteria against root-knot nematodes.

  15. Microbiological characterization of aquatic microbiomes targeting taxonomical marker genes and antibiotic resistance genes of opportunistic bacteria.

    PubMed

    Alexander, Johannes; Bollmann, Anna; Seitz, Wolfram; Schwartz, Thomas

    2015-04-15

    The dissemination of medically relevant antibiotic resistance genes (ARGs) (blaVIM-1, vanA, ampC, ermB, and mecA) and opportunistic bacteria (Enterococcus faecium/faecalis, Pseudomonas aeruginosa, Enterobacteriaceae, Staphylococcus aureus, and CNS) was determined in different anthropogenically influenced aquatic habitats in a selected region of Germany. Over a period of two years, four differently sized wastewater treatment plants (WWTPs) with and without clinical influence, three surface waters, four rain overflow basins, and three groundwater sites were analyzed by quantitative Polymerase Chain Reaction (qPCR). Results were calculated in cell equivalents per 100 ng of total DNA extracted from water samples and per 100 mL sample volume, which seems to underestimate the abundance of antibiotic resistance and opportunistic bacteria. High abundances of opportunistic bacteria and ARG were quantified in clinical wastewaters and influents of the adjacent WWTP. The removal capacities of WWTP were up to 99% for some, but not all investigated bacteria. The abundances of most ARG targets were found to be increased in the bacterial population after conventional wastewater treatment. As a consequence, downstream surface water and also some groundwater compartments displayed high abundances of all four ARGs. It became obvious that the dynamics of the ARG differed from the fate of the opportunistic bacteria. This underlines the necessity of an advanced microbial characterization of anthropogenically influenced environments.

  16. Cooperation and competition shape ecological resistance during periodic spatial disturbance of engineered bacteria.

    PubMed

    Wilson, Cortney E; Lopatkin, Allison J; Craddock, Travis J A; Driscoll, William W; Eldakar, Omar Tonsi; Lopez, Jose V; Smith, Robert P

    2017-03-27

    Cooperation is fundamental to the survival of many bacterial species. Previous studies have shown that spatial structure can both promote and suppress cooperation. Most environments where bacteria are found are periodically disturbed, which can affect the spatial structure of the population. Despite the important role that spatial disturbances play in maintaining ecological relationships, it remains unclear as to how periodic spatial disturbances affect bacteria dependent on cooperation for survival. Here, we use bacteria engineered with a strong Allee effect to investigate how the frequency of periodic spatial disturbances affects cooperation. We show that at intermediate frequencies of spatial disturbance, the ability of the bacterial population to cooperate is perturbed. A mathematical model demonstrates that periodic spatial disturbance leads to a tradeoff between accessing an autoinducer and accessing nutrients, which determines the ability of the bacteria to cooperate. Based on this relationship, we alter the ability of the bacteria to access an autoinducer. We show that increased access to an autoinducer can enhance cooperation, but can also reduce ecological resistance, defined as the ability of a population to resist changes due to disturbance. Our results may have implications in maintaining stability of microbial communities and in the treatment of infectious diseases.

  17. Recovery of metallo-tolerant and antibiotic resistant psychrophilic bacteria from Siachen glacier, Pakistan.

    PubMed

    Rafiq, Muhammad; Hayat, Muhammad; Anesio, Alexandre M; Jamil, Syed Umair Ullah; Hassan, Noor; Shah, Aamer Ali; Hasan, Fariha

    2017-01-01

    Cultureable bacterial diversity of previously unexplored Siachen glacier, Pakistan, was studied. Out of 50 isolates 33 (66%) were Gram negative and 17 (34%) Gram positive. About half of the isolates were pigment producers and were able to grow at 4-37°C. 16S rRNA gene sequences revealed Gram negative bacteria dominated by Proteobacteria (especially γ-proteobacteria and β-proteobacteria) and Flavobacteria. The genus Pseudomonas (51.51%, 17) was dominant among γ- proteobacteria. β-proteobacteria constituted 4 (12.12%) Alcaligenes and 4 (12.12%) Janthinobacterium strains. Among Gram positive bacteria, phylum Actinobacteria, Rhodococcus (23.52%, 4) and Arthrobacter (23.52%, 4) were the dominating genra. Other bacteria belonged to Phylum Firmicutes with representative genus Carnobacterium (11.76%, 2) and 4 isolates represented 4 genera Bacillus, Lysinibacillus, Staphylococcus and Planomicrobium. Most of the Gram negative bacteria were moderate halophiles, while most of the Gram positives were extreme halophiles and were able to grow up to 6.12 M of NaCl. More than 2/3 of the isolates showed antimicrobial activity against multidrug resistant S. aureus, E. coli, Klebsiella pneumonia, Enterococcus faecium, Candida albicans, Aspergillus flavus and Aspergillus fumigatus and ATCC strains. Gram positive bacteria (94.11%) were more resistant to heavy metals as compared to Gram negative (78.79%) and showed maximum tolerance against iron and least tolerance against mercury.

  18. Performance of a Heating Block System Designed for Studying the Heat Resistance of Bacteria in Foods.

    PubMed

    Kou, Xiao-Xi; Li, Rui; Hou, Li-Xia; Huang, Zhi; Ling, Bo; Wang, Shao-Jin

    2016-07-28

    Knowledge of bacteria's heat resistance is essential for developing effective thermal treatments. Choosing an appropriate test method is important to accurately determine bacteria's heat resistances. Although being a major factor to influence the thermo-tolerance of bacteria, the heating rate in samples cannot be controlled in water or oil bath methods due to main dependence on sample's thermal properties. A heating block system (HBS) was designed to regulate the heating rates in liquid, semi-solid and solid foods using a temperature controller. Distilled water, apple juice, mashed potato, almond powder and beef were selected to evaluate the HBS's performance by experiment and computer simulation. The results showed that the heating rates of 1, 5 and 10 °C/min with final set-point temperatures and holding times could be easily and precisely achieved in five selected food materials. A good agreement in sample central temperature profiles was obtained under various heating rates between experiment and simulation. The experimental and simulated results showed that the HBS could provide a sufficiently uniform heating environment in food samples. The effect of heating rate on bacterial thermal resistance was evaluated with the HBS. The system may hold potential applications for rapid and accurate assessments of bacteria's thermo-tolerances.

  19. Arsenic resistance and accumulation by two bacteria isolated from a natural arsenic contaminated site.

    PubMed

    Pandey, Neha; Bhatt, Renu

    2015-11-01

    Forty-three indigenous arsenic resistant bacteria were isolated from arsenic rich soil of Rajnandgaon district in the state of Chhattisgarh, India by enrichment culture technique. Among the isolates, two of the bacteria (As-9 and As-14) exhibited high resistance to As(V) [MIC ≥ 700 mM] and As(III) [MIC ≥ 10 mM] and were selected for further studies. Both these bacteria grew well in the presence of arsenic [20 mM As(V) and 5 mM As(III)], but the isolate As-14 strictly required arsenic for its survival and growth and was characterized as a novel arsenic dependent bacterium. The isolates contributed to 99% removal of arsenic from the growth medium which was efficiently accumulated in the cell. Quantitative estimation of arsenic through Atomic Absorption Spectrophotometer revealed that there was >60% accumulation of both As(V) and As(III) by the two isolates. Scanning Electron Microscopic analysis showed a fourfold increase in bacterial cell volume when grown in the presence of arsenic and the results of Transmission Electron Microscopy and energy-dispersive X-ray spectroscopy proved that such an alteration was due to arsenic accumulation. Such arsenic resistant bacteria with efficient accumulating property could be effectively applied in the treatment of arsenic contaminated water.

  20. Native California soils are selective reservoirs for multidrug-resistant bacteria.

    PubMed

    Hollowell, Amanda C; Gano, Kelsey A; Lopez, Gabriel; Shahin, Kareem; Regus, John U; Gleason, Nathaniel; Graeter, Stefanie; Pahua, Victor; Sachs, Joel L

    2015-06-01

    Soil bacteria can exhibit extensive antibiotic resistomes and act as reservoirs of important antibiotic resistance traits. However, the geographic sources and evolutionary drivers of resistance traits are poorly understood in these natural settings. We investigated the prevalence, spatial structure and evolutionary drivers of multidrug resistance in natural populations of Bradyrhizobium, a cosmopolitan bacterial lineage that thrives in soil and aquatic systems as well as in plant and human hosts. We genotyped > 400 isolates from plant roots and soils across California and assayed 98 of them for resistance traits against 17 clinically relevant antibiotics. We investigated the geographic and phylogenetic structure of resistance traits, and analysed correlations of resistance with strain abundance, host infection capacity and in vitro fitness. We found: (i) multidrug resistance at all sites, (ii) subsets of resistance traits that are spatially structured and (iii) significant associations between resistance traits and increased strain abundance or host infection capacity. Our results highlight multiple selective factors that can result in the spread of resistance traits in native Bradyrhizobium populations.

  1. Adaptive resistance in bacteria requires epigenetic inheritance, genetic noise, and cost of efflux pumps.

    PubMed

    Motta, Santiago Sandoval; Cluzel, Philippe; Aldana, Maximino

    2015-01-01

    Adaptive resistance emerges when populations of bacteria are subjected to gradual increases of antibiotics. It is characterized by a rapid emergence of resistance and fast reversibility to the non-resistant phenotype when the antibiotic is removed from the medium. Recent work shows that adaptive resistance requires epigenetic inheritance and heterogeneity of gene expression patterns that are, in particular, associated with the production of porins and efflux pumps. However, the precise mechanisms by which inheritance and variability govern adaptive resistance, and what processes cause its reversibility remain unclear. Here, using an efflux pump regulatory network (EPRN) model, we show that the following three mechanisms are essential to obtain adaptive resistance in a bacterial population: 1) intrinsic variability in the expression of the EPRN transcription factors; 2) epigenetic inheritance of the transcription rate of EPRN associated genes; and 3) energetic cost of the efflux pumps activity that slows down cell growth. While the first two mechanisms acting together are responsible for the emergence and gradual increase of the resistance, the third one accounts for its reversibility. In contrast with the standard assumption, our model predicts that adaptive resistance cannot be explained by increased mutation rates. Our results identify the molecular mechanism of epigenetic inheritance as the main target for therapeutic treatments against the emergence of adaptive resistance. Finally, our theoretical framework unifies known and newly identified determinants such as the burden of efflux pumps that underlie bacterial adaptive resistance to antibiotics.

  2. Adaptive Resistance in Bacteria Requires Epigenetic Inheritance, Genetic Noise, and Cost of Efflux Pumps

    PubMed Central

    Motta, Santiago Sandoval; Cluzel, Philippe; Aldana, Maximino

    2015-01-01

    Adaptive resistance emerges when populations of bacteria are subjected to gradual increases of antibiotics. It is characterized by a rapid emergence of resistance and fast reversibility to the non-resistant phenotype when the antibiotic is removed from the medium. Recent work shows that adaptive resistance requires epigenetic inheritance and heterogeneity of gene expression patterns that are, in particular, associated with the production of porins and efflux pumps. However, the precise mechanisms by which inheritance and variability govern adaptive resistance, and what processes cause its reversibility remain unclear. Here, using an efflux pump regulatory network (EPRN) model, we show that the following three mechanisms are essential to obtain adaptive resistance in a bacterial population: 1) intrinsic variability in the expression of the EPRN transcription factors; 2) epigenetic inheritance of the transcription rate of EPRN associated genes; and 3) energetic cost of the efflux pumps activity that slows down cell growth. While the first two mechanisms acting together are responsible for the emergence and gradual increase of the resistance, the third one accounts for its reversibility. In contrast with the standard assumption, our model predicts that adaptive resistance cannot be explained by increased mutation rates. Our results identify the molecular mechanism of epigenetic inheritance as the main target for therapeutic treatments against the emergence of adaptive resistance. Finally, our theoretical framework unifies known and newly identified determinants such as the burden of efflux pumps that underlie bacterial adaptive resistance to antibiotics. PMID:25781931

  3. Deoxynybomycins inhibit mutant DNA gyrase and rescue mice infected with fluoroquinolone-resistant bacteria

    PubMed Central

    Parkinson, Elizabeth I.; Bair, Joseph S.; Nakamura, Bradley A.; Lee, Hyang Y.; Kuttab, Hani I.; Southgate, Emma H.; Lezmi, Stéphane; Lau, Gee W.; Hergenrother, Paul J.

    2015-01-01

    Fluoroquinolones are one of the most commonly prescribed classes of antibiotics, but fluoroquinolone resistance (FQR) is widespread and increasing. Deoxynybomycin (DNM) is a natural-product antibiotic with an unusual mechanism of action, inhibiting the mutant DNA gyrase that confers FQR. Unfortunately, isolation of DNM is difficult and DNM is insoluble in aqueous solutions, making it a poor candidate for development. Here we describe a facile chemical route to produce DNM and its derivatives. These compounds possess excellent activity against FQR methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci clinical isolates and inhibit mutant DNA gyrase in-vitro. Bacteria that develop resistance to DNM are re-sensitized to fluoroquinolones, suggesting that resistance that emerges to DNM would be treatable. Using a DNM derivative, the first in-vivo efficacy of the nybomycin class is demonstrated in a mouse infection model. Overall, the data presented suggest the promise of DNM derivatives for the treatment of FQR infections. PMID:25907309

  4. The expression of antibiotic resistance genes in antibiotic-producing bacteria.

    PubMed

    Mak, Stefanie; Xu, Ye; Nodwell, Justin R

    2014-08-01

    Antibiotic-producing bacteria encode antibiotic resistance genes that protect them from the biologically active molecules that they produce. The expression of these genes needs to occur in a timely manner: either in advance of or concomitantly with biosynthesis. It appears that there have been at least two general solutions to this problem. In many cases, the expression of resistance genes is tightly linked to that of antibiotic biosynthetic genes. In others, the resistance genes can be induced by their cognate antibiotics or by intermediate molecules from their biosynthetic pathways. The regulatory mechanisms that couple resistance to antibiotic biosynthesis are mechanistically diverse and potentially relevant to the origins of clinical antibiotic resistance. © 2014 John Wiley & Sons Ltd.

  5. Deoxynybomycins inhibit mutant DNA gyrase and rescue mice infected with fluoroquinolone-resistant bacteria.

    PubMed

    Parkinson, Elizabeth I; Bair, Joseph S; Nakamura, Bradley A; Lee, Hyang Y; Kuttab, Hani I; Southgate, Emma H; Lezmi, Stéphane; Lau, Gee W; Hergenrother, Paul J

    2015-04-24

    Fluoroquinolones are one of the most commonly prescribed classes of antibiotics, but fluoroquinolone resistance (FQR) is widespread and increasing. Deoxynybomycin (DNM) is a natural-product antibiotic with an unusual mechanism of action, inhibiting the mutant DNA gyrase that confers FQR. Unfortunately, isolation of DNM is difficult and DNM is insoluble in aqueous solutions, making it a poor candidate for development. Here we describe a facile chemical route to produce DNM and its derivatives. These compounds possess excellent activity against FQR methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci clinical isolates and inhibit mutant DNA gyrase in-vitro. Bacteria that develop resistance to DNM are re-sensitized to fluoroquinolones, suggesting that resistance that emerges to DNM would be treatable. Using a DNM derivative, the first in-vivo efficacy of the nybomycin class is demonstrated in a mouse infection model. Overall, the data presented suggest the promise of DNM derivatives for the treatment of FQR infections.

  6. Iron metabolism and resistance to infection by invasive bacteria in the social amoeba Dictyostelium discoideum.

    PubMed

    Bozzaro, Salvatore; Buracco, Simona; Peracino, Barbara

    2013-01-01

    Dictyostelium cells are forest soil amoebae, which feed on bacteria and proliferate as solitary cells until bacteria are consumed. Starvation triggers a change in life style, forcing cells to gather into aggregates to form multicellular organisms capable of cell differentiation and morphogenesis. As a soil amoeba and a phagocyte that grazes on bacteria as the obligate source of food, Dictyostelium could be a natural host of pathogenic bacteria. Indeed, many pathogens that occasionally infect humans are hosted for most of their time in protozoa or free-living amoebae, where evolution of their virulence traits occurs. Due to these features and its amenability to genetic manipulation, Dictyostelium has become a valuable model organism for studying strategies of both the host to resist infection and the pathogen to escape the defense mechanisms. Similarly to higher eukaryotes, iron homeostasis is crucial for Dictyostelium resistance to invasive bacteria. Iron is essential for Dictyostelium, as both iron deficiency or overload inhibit cell growth. The Dictyostelium genome shares with mammals many genes regulating iron homeostasis. Iron transporters of the Nramp (Slc11A) family are represented with two genes, encoding Nramp1 and Nramp2. Like the mammalian ortholog, Nramp1 is recruited to phagosomes and macropinosomes, whereas Nramp2 is a membrane protein of the contractile vacuole network, which regulates osmolarity. Nramp1 and Nramp2 localization in distinct compartments suggests that both proteins synergistically regulate iron homeostasis. Rather than by absorption via membrane transporters, iron is likely gained by degradation of ingested bacteria and efflux via Nramp1 from phagosomes to the cytosol. Nramp gene disruption increases Dictyostelium sensitivity to infection, enhancing intracellular growth of Legionella or Mycobacteria. Generation of mutants in other "iron genes" will help identify genes essential for iron homeostasis and resistance to pathogens.

  7. In vitro antibacterial potency of Butea monosperma Lam. against 12 clinically isolated multidrug resistant bacteria

    PubMed Central

    Sahu, Mahesh Chandra; Padhy, Rabindra Nath

    2013-01-01

    Objective To investigate the antibacterial activity, using cold and hot extraction procedures with five solvents, petroleum ether, acetone, ethanol, methanol and water to validate medicinal uses of Butea monosperma Lam (B. monosperma) in controlling infections; and to qualitatively estimate phytochemical constituents of leaf-extracts of the plant. Methods The antibacterial activity of leaf-extracts was evaluated by the agar-well diffusion method against clinically isolated 12 Gram-positive and -negative multidrug resistant (MDR) pathogenic bacteria in vitro. Values of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of leaf-extracts against each bacterium were obtained in a 96-well micro-titre plate, by broth dilution micro-titre plate technique. Results The presence of tannins, flavonoids, starch, glycosides and carbohydrates in different leaf extracts was established. Pathogenic bacteria used were, Acinetobacter sp., Chromobacterium violaceum, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella sp., Enterococcus sp., Staphylococcus aureus (S. aureus), methicillin resistant S. aureus and vancomycin resistant S. aureus, along with standard bacterial strains. These MDR bacteria had been recorded to have significant inhibitions by leaf extracts, obtained by cold and hot extraction procedures with five solvents. In addition, the hot aqueous extract against Enterococcus sp. had the highest inhibition zone-size (21 mm). Ciprofloxacin 30 µg/disc was the positive/reference control and the diluting solvent, 10% dimethyl sulphoxide was the negative control. Recorded MIC values of different extracts ranged between 0.23 and 13.30 mg/mL, and MBC values were 0.52 to 30.00 mg/mL, for these bacteria. Conclusions Leaf-extracts with hot water and ethanol had shown significant antibacterial activity against all bacteria. B. monosperma leaf-extract could be used in treating infectious

  8. Reflection-type long period grating biosensor for the detection of drug resistant bacteria: The Opto-bacteria Project

    NASA Astrophysics Data System (ADS)

    Consales, M.; Quero, G.; Zuppolini, S.; Sansone, L.; Borriello, A.; Giordano, M.; Venturelli, A.; Cusano, A.

    2014-05-01

    We report on the development of a multilayer coated reflection-type long period fiber grating (LPG) biosensor, useful for the detection of antibiotic resistance bacteria. A standard LPG is first transformed in a more practical probe working in reflection mode, then it is coated by a primary layer of aPS and a secondary layer of PMMA in order to increase its surrounding refractive index sensitivity and at the same time provide the necessary conditions for a correct biofunctionalization. Standard linkage chemistry has been applied to anchor the bioreceptors on the probe surface. We show some preliminary results demonstrating the capability of our LPG biosensor to successfully monitor all the biological steps of the biomolecular experiments, including β-lactamase binding detection tests.

  9. Co-occurrence of antibiotic drugs, resistant bacteria and resistance genes in runoff from cattle feedlots

    USDA-ARS?s Scientific Manuscript database

    Agricultural uses of antibiotics raises concerns about the development of antibiotic resistance in food animals, and the potential to transmit resistance to human clinical settings via fecal contamination of surface and ground water. Although there is broad agreement that agricultural resistance can...

  10. Antibiotic resistance monitoring in heterotrophic bacteria from anthropogenic-polluted seawater and the intestines of oyster Crassostrea hongkongensis.

    PubMed

    Wang, Rui Xuan; Wang, AnLi; Wang, Jiang Yong

    2014-11-01

    A total of 1,050 strains of heterotrophic bacteria isolated from farming seawater and the intestines of oyster species Crassostrea hongkongensis were tested for resistance to 10 antibiotics by the Kirby-Bauer diffusion method. The resistant rates of seawater-derived bacteria to chloramphenicol, enrofloxacin, and ciprofloxacin were low (less than 20%), whereas the bacteria obtained from oysters showed low resistance to chloramphenicol and enrofloxacin. Many strains showed high resistant rates (more than 40%) to furazolidone, penicillin G, and rifampin. A total of 285 strains from farming seawater and oysters were resistant to more than three antibiotics. Several strains showed resistance to more than nine antibiotics. Furthermore, the peak resistant rates of the seawater-derived strains to multiple antibiotics overlapped in April, June, September, and November, and those of oyster-derived strains overlapped during April, July, and September. The multi-resistant rate patterns of strains from farming seawater and oyster intestines were similar.

  11. Efficacy of Antibacterial Peptides Against Peptide-Resistant MRSA Is Restored by Permeabilization of Bacteria Membranes

    PubMed Central

    Ravensdale, Joshua; Wong, Zachary; O’Brien, Frances; Gregg, Keith

    2016-01-01

    Clinical application of antimicrobial peptides (AMPs), as with conventional antibiotics, may be compromised by the development of bacterial resistance. This study investigated AMP resistance in methicillin resistant Staphylococcus aureus, including aspects related to the resilience of the resistant bacteria toward the peptides, the stability of resistance when selection pressures are removed, and whether resistance can be overcome by using the peptides with other membrane-permeabilising agents. Genotypically variant strains of S. aureus became equally resistant to the antibacterial peptides melittin and bac8c when grown in sub-lethal concentrations. Subculture of a melittin-resistant strain without melittin for 8 days lowered the minimal lethal concentration of the peptide from 170 μg ml-1 to 30 μg ml-1. Growth for 24 h in 12 μg ml-1 melittin restored the MLC to 100 μg ml-1. Flow cytometry analysis of cationic fluorophore binding to melittin-naïve and melittin-resistant bacteria revealed that resistance coincided with decreased binding of cationic molecules, suggesting a reduction in nett negative charge on the membrane. Melittin was haemolytic at low concentrations but the truncated analog of melittin, mel12-26, was confirmed to lack haemolytic activity. Although a previous report found that mel12-26 retained full bactericidal activity, we found it to lack significant activity when added to culture medium. However, electroporation in the presence of 50 μg ml-1 of mel12-26, killed 99.3% of the bacteria. Similarly, using a low concentration of the non-ionic detergent Triton X-100 to permeabilize bacteria to mel12-26 markedly increased its bactericidal activity. The observation that bactericidal activity of the non-membranolytic peptide mel12-26 was enhanced when the bacterial membrane was permeablized by detergents or electroporation, suggests that its principal mechanism in reducing bacterial survival may be through interaction with intracellular organelles

  12. Bacteria isolated from sewage influent resistant to ciprofloxacin, chloramphenicol and tetracycline.

    PubMed

    Zwenger, Sam R; Gillock, Eric T

    2009-02-01

    This study assessed the presence of antibiotic-resistant bacteria in sewage influent. Resistance was measured by determining the lowest concentration of antibiotic, in micrograms per milliliter (microg mL(- 1)). To determine the minimum inhibitory concentration (MIC), which is used in diagnostic laboratories, we used the Etest, a plastic strip containing an antibiotic concentration gradient. In total, we sampled five sewage treatment plants of various sizes in Kansas and isolated bacteria resistant to three broad-spectrum antibiotics; ciprofloxacin (1-cyclopropyl-6-fluoro-4-oxo-7-piperazin-1-yl-quinoline-3-carboxylic acid), chloramphenicol 2,2-dichlor-N-[(aR, bR)-b-hydroxy-a-hydroxymethyl-4-nitrophenethyl] acetamide), and tetracycline (2-(amino-hydroxy-ethylidene)-4-dimethylamino-6,10,11,12a-tetrahydroxy-6-methyl-4,4a,5,5a-tetrahydrotetracene-1,3,12-trione). In total, 25 Gram-negative isolates were found to be resistant to at least one of the antibiotics tested. Some isolates were multi-drug resistant, regardless of the amount of influent the sewage treatment plant received. A Pseudomonas isolate from the smallest sewage treatment plant (approximately 2 million gallons treated per day) showed resistance to all three antibiotics, albeit at low levels (10 microg mL(- 1)). The largest number of bacteria (6 species) were isolated from the largest sewage treatment plant (45 million gallons per day). Regardless, the results of this study are in agreement with similar studies, antibiotic resistance can persist long after the antibiotics have been forgotten.

  13. Xenopus laevis oocytes infected with multi-drug-resistant bacteria: implications for electrical recordings.

    PubMed

    O'Connell, Denice; Mruk, Karen; Rocheleau, Jessica M; Kobertz, William R

    2011-08-01

    The Xenopus laevis oocyte has been the workhorse for the investigation of ion transport proteins. These large cells have spawned a multitude of novel techniques that are unfathomable in mammalian cells, yet the fickleness of the oocyte has driven many researchers to use other membrane protein expression systems. Here, we show that some colonies of Xenopus laevis are infected with three multi-drug-resistant bacteria: Pseudomonas fluorescens, Pseudomonas putida, and Stenotrophomonas maltophilia. Oocytes extracted from infected frogs quickly (3-4 d) develop multiple black foci on the animal pole, similar to microinjection scars, which render the extracted eggs useless for electrical recordings. Although multi-drug resistant, the bacteria were susceptible to amikacin and ciprofloxacin in growth assays. Supplementing the oocyte storage media with these two antibiotics prevented the appearance of the black foci and afforded oocytes suitable for whole-cell recordings. Given that P. fluorescens associated with X. laevis has become rapidly drug resistant, it is imperative that researchers store the extracted oocytes in the antibiotic cocktail and not treat the animals harboring the multi-drug-resistant bacteria.

  14. Nontoxic colloidal particles impede antibiotic resistance of swarming bacteria by disrupting collective motion and speed

    NASA Astrophysics Data System (ADS)

    Lu, Shengtao; Liu, Fang; Xing, Bengang; Yeow, Edwin K. L.

    2015-12-01

    A monolayer of swarming B. subtilis on semisolid agar is shown to display enhanced resistance against antibacterial drugs due to their collective behavior and motility. The dynamics of swarming motion, visualized in real time using time-lapse microscopy, prevents the bacteria from prolonged exposure to lethal drug concentrations. The elevated drug resistance is significantly reduced when the collective motion of bacteria is judiciously disrupted using nontoxic polystyrene colloidal particles immobilized on the agar surface. The colloidal particles block and hinder the motion of the cells, and force large swarming rafts to break up into smaller packs in order to maneuver across narrow spaces between densely packed particles. In this manner, cohesive rafts rapidly lose their collectivity, speed, and group dynamics, and the cells become vulnerable to the drugs. The antibiotic resistance capability of swarming B. subtilis is experimentally observed to be negatively correlated with the number density of colloidal particles on the engineered surface. This relationship is further tested using an improved self-propelled particle model that takes into account interparticle alignment and hard-core repulsion. This work has pertinent implications on the design of optimal methods to treat drug resistant bacteria commonly found in swarming colonies.

  15. [Bacteria and resistance to antibiotics in acute otitis media in paediatrics, depending on the geographical origin].

    PubMed

    Bidet, Philippe; Doit, Catherine; Bingen, Edouard

    2003-11-22

    EPIDEMIOLOGY OF THE BACTERIA RESPONSIBLE: Acute otitis media (AOM) is the most common bacterial infection in childhood below the age of 5 years. Bacteria may be isolated from middle ear fluid in about two-thirds of patients. The prevalence of bacteria varies from one country to the next. The most common pathogens recovered are Streptococcus pneumoniae, Haemophilus influenzae (20-50%) and less frequently Moraxella catarrhalis (10%). However, several recent reports suggest an increasing rate of isolation of M. catarrhalis approaching 20%. Concomitant isolation of two or more organisms occurs in up to 10% of cases. The role of Group A Streptococci and Staphylococcus aureus in AOM has decreased since the use of antibiotics. EPIDEMIOLOGY OF ANTIMICROBIAL RESISTANCE: The recent spread of penicillin resistant S. pneumoniae and amoxycillin resistant H. influenzae varies considerably from one country to an other and appears related to the use of antibiotics and socio-economic conditions. A follow up of bacterial epidemiology and antibiotic resistance is necessary in each region of the world to define accurate strategies of acute otitis antibiotherapy.

  16. Aerobic Mercury-resistant bacteria alter Mercury speciation and retention in the Tagus Estuary (Portugal).

    PubMed

    Figueiredo, Neusa L; Canário, João; O'Driscoll, Nelson J; Duarte, Aida; Carvalho, Cristina

    2016-02-01

    Aerobic mercury-resistant bacteria were isolated from the sediments of two highly mercury-polluted areas of the Tagus Estuary (Barreiro and Cala do Norte) and one natural reserve area (Alcochete) in order to test their capacity to transform mercury. Bacterial species were identified using 16S rRNA amplification and sequencing techniques and the results indicate the prevalence of Bacillus sp. Resistance patterns to mercurial compounds were established by the determination of minimal inhibitory concentrations. Representative Hg-resistant bacteria were further tested for transformation pathways (reduction, volatilization and methylation) in cultures containing mercury chloride. Bacterial Hg-methylation was carried out by Vibrio fluvialis, Bacillus megaterium and Serratia marcescens that transformed 2-8% of total mercury into methylmercury in 48h. In addition, most of the HgR bacterial isolates showed Hg(2+)-reduction andHg(0)-volatilization resulting 6-50% mercury loss from the culture media. In summary, the results obtained under controlled laboratory conditions indicate that aerobic Hg-resistant bacteria from the Tagus Estuary significantly affect both the methylation and reduction of mercury and may have a dual face by providing a pathway for pollution dispersion while forming methylmercury, which is highly toxic for living organisms.

  17. Nontoxic colloidal particles impede antibiotic resistance of swarming bacteria by disrupting collective motion and speed.

    PubMed

    Lu, Shengtao; Liu, Fang; Xing, Bengang; Yeow, Edwin K L

    2015-12-01

    A monolayer of swarming B. subtilis on semisolid agar is shown to display enhanced resistance against antibacterial drugs due to their collective behavior and motility. The dynamics of swarming motion, visualized in real time using time-lapse microscopy, prevents the bacteria from prolonged exposure to lethal drug concentrations. The elevated drug resistance is significantly reduced when the collective motion of bacteria is judiciously disrupted using nontoxic polystyrene colloidal particles immobilized on the agar surface. The colloidal particles block and hinder the motion of the cells, and force large swarming rafts to break up into smaller packs in order to maneuver across narrow spaces between densely packed particles. In this manner, cohesive rafts rapidly lose their collectivity, speed, and group dynamics, and the cells become vulnerable to the drugs. The antibiotic resistance capability of swarming B. subtilis is experimentally observed to be negatively correlated with the number density of colloidal particles on the engineered surface. This relationship is further tested using an improved self-propelled particle model that takes into account interparticle alignment and hard-core repulsion. This work has pertinent implications on the design of optimal methods to treat drug resistant bacteria commonly found in swarming colonies.

  18. Viability of multiple antibiotic resistant bacteria in distribution lines of treated sewage effluent used for irrigation.

    PubMed

    Al-Bahry, S N; Mahmoud, I Y; Al-Khaifi, A; Elshafie, A E; Al-Harthy, A

    2009-01-01

    Viability of multiple antibiotic resistant bacteria (MARB) in tertiary treated sewage effluent (TTSE) used for irrigation, was investigated at the Sultan Qaboos University sewage treatment plant (STP). This water recycle system is used here as a model for the systems commonly used throughout Oman and the Gulf region. Samples of TTSE were collected weekly from four sites, 1.5 km from each other. Chlorine levels declined gradually at the three sites with increasing distance from the STP. Viable bacteria, coliforms and nitrate concentrations increased significantly while biological oxygen demand (BOD) declined after STP chlorination. Mean values of turbidity changed slightly. Trace elements values were insignificant. A total of 336 bacteria from 8 genera revealed that the dominant isolates were Enterobacter spp., Pseudomonas spp., and Aeromonas spp. Among the isolates 59.8% were multiply resistant to several antibiotics. Resistance was higher to ampicillin followed by sulphamethoxazole, carbenicillin, streptomycine and minocycline. Frequency of resistance to the 14 antibiotics varied among the isolates. The present system related to the viability of MARB in TTSE used for irrigation may have serious implications for public health and wildlife. Results of this investigation will be of value in modifying current STPs systems and thus avoiding serious health issues.

  19. Priming innate immune responses to infection by cyclooxygenase inhibition kills antibiotic susceptible and resistant bacteria

    PubMed Central

    Stables, Melanie J.; Newson, Justine; Ayoub, Samir S.; Brown, Jeremy; Hyams, Catherine J.; Gilroy, Derek W.

    2017-01-01

    Inhibition of cyclooxygenase (COX)-derived prostaglandins (PGs) by non-steroidal anti-inflammatory drugs (NSAIDs) mediates leukocyte killing of bacteria. However, the relative contribution of COX 1 versus COX 2 to this process as well as the mechanisms controlling it in mouse and humans are unknown. Indeed, the potential of NSAIDs to facilitate leukocyte killing of drug-resistance bacteria warrants investigation. Therefore, we carried a series of experiments in mouse and humans finding that COX 1 is the predominant isoform active in PG synthesis during infection and that its prophylactic or therapeutic inhibition primes leukocytes to kill bacteria by increasing phagocytic uptake and reactive oxygen intermediate-mediated killing in a cAMP-dependent manner. Moreover, NSAIDs enhance bacterial killing in humans, exerting an additive effect when used in combination with antibiotics. Finally, NSAIDs, through the inhibition of COX prime the innate immune system to mediate bacterial clearance of penicillin-resistant Streptococcus pneumoniae serotype 19A, which is a well recognised vaccine escape serotype of particular concern given its increasing prevalence and multi-antibiotic resistance. Therefore, these data underline the importance of lipid mediators in host responses to infection and the potential of inhibitors of PG signaling pathways as adjunctive therapies, particularly in the context of antibiotic resistance. PMID:20606163

  20. Survey of antibiotic-resistant bacteria isolated from bottlenose dolphins Tursiops truncatus in the southeastern USA.

    PubMed

    Stewart, Jill R; Townsend, Forrest I; Lane, Suzanne M; Dyar, Elizabeth; Hohn, Aleta A; Rowles, Teri K; Staggs, Lydia A; Wells, Randall S; Balmer, Brian C; Schwacke, Lori H

    2014-02-19

    Contamination of coastal waters can carry pathogens and contaminants that cause diseases in humans and wildlife, and these pathogens can be transported by water to areas where they are not indigenous. Marine mammals may be indicators of potential health effects from such pathogens and toxins. Here we isolated bacterial species of relevance to humans from wild bottlenose dolphins Tursiops truncatus and assayed isolated bacteria for antibiotic resistance. Samples were collected during capture-release dolphin health assessments at multiple coastal and estuarine sites along the US mid-Atlantic coast and the Gulf of Mexico. These samples were transported on ice and evaluated using commercial systems and aerobic culture techniques routinely employed in clinical laboratories. The most common bacteria identified were species belonging to the genus Vibrio, although Escherichia coli, Shewanella putrefaciens, and Pseudomonas fluorescens/putida were also common. Some of the bacterial species identified have been associated with human illness, including a strain of methicillin-resistant Staphylococcus aureus (MRSA) identified in 1 sample. Widespread antibiotic resistance was observed among all sites, although the percentage of resistant isolates varied across sites and across time. These data provide a baseline for future comparisons of the bacteria that colonize bottlenose dolphins in the southeastern USA.

  1. Ozone treatment of conditioned wastewater selects antibiotic resistance genes, opportunistic bacteria, and induce strong population shifts.

    PubMed

    Alexander, Johannes; Knopp, Gregor; Dötsch, Andreas; Wieland, Arne; Schwartz, Thomas

    2016-07-15

    An ozone treatment system was investigated to analyze its impact on clinically relevant antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs). A concentration of 0.9±0.1g ozone per 1g DOC was used to treat conventional clarified wastewater. PCR, qPCR analyses, Illumina 16S Amplicon Sequencing, and PCR-DGGE revealed diverse patterns of resistances and susceptibilities of opportunistic bacteria and accumulations of some ARGs after ozone treatment. Molecular marker genes for enterococci indicated a high susceptibility to ozone. Although they were reduced by almost 99%, they were still present in the bacterial population after ozone treatment. In contrast to this, Pseudomonas aeruginosa displayed only minor changes in abundance after ozone treatment. This indicated different mechanisms of microorganisms to cope with the bactericidal effects of ozone. The investigated ARGs demonstrated an even more diverse pattern. After ozone treatment, the erythromycin resistance gene (ermB) was reduced by 2 orders of magnitude, but simultaneously, the abundance of two other clinically relevant ARGs increased within the surviving wastewater population (vanA, blaVIM). PCR-DGGE analysis and 16S-Amplicon-Sequencing confirmed a selection-like process in combination with a substantial diversity loss within the vital wastewater population after ozone treatment. Especially the PCR-DGGE results demonstrated the survival of GC-rich bacteria after ozone treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. [Inactivation of the chlorine-resistant bacteria isolated from the drinking water distribution system].

    PubMed

    Chen, Yu-Qiao; Duan, Xiao-Di; Lu, Pin-Pin; Wang, Qian; Zhang, Xiao-Jian; Chen, Chao

    2012-01-01

    Inactivation experiments of seven strains of chlorine-resistant bacteria, isolated from a drinking water distribution system, were conducted with four kinds of disinfectants. All the bacteria showed high resistance to chlorine, especially for Mycobacterium mucogenicum. The CT value of 99.9% inactivation for M. mucogenicum, Sphingomonas sanguinis and Methylobacterium were 120 mg x (L x min)(-1), 7 mg x (L x min)(-1) and 4 mg x (L x min)(-1), respectively. The results of inactivation experiments showed that chlorine dioxide and potassium monopersulfate could inactive 5 lg of M. mucogenicum within 30 min, which showed significantly higher efficiency than free chlorine and monochloramine. Free chlorine was less effective because the disinfectant decayed very quickly. Chloramination needed higher concentration to meet the disinfection requirements. The verified dosage of disinfectants, which could effectively inactivate 99.9% of the highly chlorine-resistant M. mucogenicum within 1 h, were 3.0 mg/L monochloramine, 1.0 mg/L chlorine dioxide (as Cl2), and 1.0 mg/L potassium monopersulfate (as Cl2). It was suggested that the water treatment plants increase the concentration of monochloramine or apply chlorine dioxide intermittently to control the disinfectant-resistant bacteria.

  3. Activity of topical antimicrobial agents against multidrug-resistant bacteria recovered from burn patients.

    PubMed

    Glasser, Jessie S; Guymon, Charles H; Mende, Katrin; Wolf, Steven E; Hospenthal, Duane R; Murray, Clinton K

    2010-12-01

    Topical antimicrobials are employed for prophylaxis and treatment of burn wound infections despite no established susceptibility breakpoints, which are becoming vital in an era of multidrug-resistant (MDR) bacteria. We compared two methods of determining topical antimicrobial susceptibilities. Isolates of Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), extended spectrum beta-lactamase (ESBL) producing Klebsiella pneumoniae, and Acinetobacter baumanii-calcoaceticus (ABC) from burn patients were tested using broth microdilution and agar well diffusion to determine minimum inhibitory concentrations (MICs) and zones of inhibition (ZI). Isolates had systemic antibiotic resistance and clonality determined. MDR included resistance to antibiotics in three or more classes. We assessed 22 ESBL-producing K. pneumoniae, 20 ABC (75% MDR), 20 P. aeruginosa (45% MDR), and 20 MRSA isolates. The most active agents were mupirocin for MRSA and mafenide acetate for the gram-negatives with moderate MICs/ZI found with silver sulfadiazene, silver nitrate, and honey. MDR and non-MDR isolates had similar topical resistance. There was no clonality associated with resistance patterns. Despite several methods to test bacteria for topical susceptibility, no defined breakpoints exist and standards need to be established. We recommend continuing to use silver products for prophylaxis against gram-negatives and mafenide acetate for treatment, and mupirocin for MRSA. Published by Elsevier Ltd.

  4. Occurrence of antibiotic resistance in bacteria isolated from seawater organisms caught in Campania Region: preliminary study.

    PubMed

    Smaldone, Giorgio; Marrone, Raffaele; Cappiello, Silvia; Martin, Giuseppe A; Oliva, Gaetano; Cortesi, Maria L; Anastasio, Aniello

    2014-07-15

    Environmental contamination by pharmaceuticals is a public health concern: drugs administered to humans and animals are excreted with urine or faeces and attend the sewage treatment. The main consequences of use and abuse of antibiotics is the development and diffusion of antibiotic resistance that has become a serious global problem. Aim of the study is to evaluate the presence of antimicrobial residues and to assess the antimicrobial resistance in bacteria species isolated from different wild caught seawater fish and fishery products. Three antibiotic substances (Oxytetracicline, Sulfamethoxazole and Trimethoprim) were detected (by screening and confirmatory methods) in Octopus vulgaris, Sepia officinalis and Thais haemastoma. All Vibrio strains isolated from fish were resistant to Vancomycin (VA) and Penicillin (P). In Vibrio alginolyticus, isolated in Octopus vulgaris, a resistance against 9 antibiotics was noted. Wild caught seawater fish collected in Gulf of Salerno (Campania Region), especially in marine areas including mouths of streams, were contaminated with antibiotic-resistant bacteria strains and that they might play an important role in the spread of antibiotic-resistance.

  5. Implications of stress-induced genetic variation for minimizing multidrug resistance in bacteria.

    PubMed

    Obolski, Uri; Hadany, Lilach

    2012-08-13

    Antibiotic resistance in bacterial infections is a growing threat to public health. Recent evidence shows that when exposed to stressful conditions, some bacteria perform higher rates of horizontal gene transfer and mutation, and thus acquire antibiotic resistance more rapidly. We incorporate this new notion into a mathematical model for the emergence of antibiotic multi-resistance in a hospital setting. We show that when stress has a considerable effect on genetic variation, the emergence of antibiotic resistance is dramatically affected. A strategy in which patients receive a combination of antibiotics (combining) is expected to facilitate the emergence of multi-resistant bacteria when genetic variation is stress-induced. The preference between a strategy in which one of two effective drugs is assigned randomly to each patient (mixing), and a strategy where only one drug is administered for a specific period of time (cycling) is determined by the resistance acquisition mechanisms. We discuss several features of the mechanisms by which stress affects variation and predict the conditions for success of different antibiotic treatment strategies. These findings should encourage research on the mechanisms of stress-induced genetic variation and establish the importance of incorporating data about these mechanisms when considering antibiotic treatment strategies.

  6. Occurrence of antibiotic resistance in bacteria isolated from seawater organisms caught in Campania Region: preliminary study

    PubMed Central

    2014-01-01

    Background Environmental contamination by pharmaceuticals is a public health concern: drugs administered to humans and animals are excreted with urine or faeces and attend the sewage treatment. The main consequences of use and abuse of antibiotics is the development and diffusion of antibiotic resistance that has become a serious global problem. Aim of the study is to evaluate the presence of antimicrobial residues and to assess the antimicrobial resistance in bacteria species isolated from different wild caught seawater fish and fishery products. Results Three antibiotic substances (Oxytetracicline, Sulfamethoxazole and Trimethoprim) were detected (by screening and confirmatory methods) in Octopus vulgaris, Sepia officinalis and Thais haemastoma. All Vibrio strains isolated from fish were resistant to Vancomycin (VA) and Penicillin (P). In Vibrio alginolyticus, isolated in Octopus vulgaris, a resistance against 9 antibiotics was noted. Conclusions Wild caught seawater fish collected in Gulf of Salerno (Campania Region), especially in marine areas including mouths of streams, were contaminated with antibiotic-resistant bacteria strains and that they might play an important role in the spread of antibiotic-resistance. PMID:25027759

  7. The challenge of efflux-mediated antibiotic resistance in Gram-negative bacteria.

    PubMed

    Li, Xian-Zhi; Plésiat, Patrick; Nikaido, Hiroshi

    2015-04-01

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

  8. Targeting Pan-Resistant Bacteria With Antibodies to a Broadly Conserved Surface Polysaccharide Expressed During Infection

    PubMed Central

    Skurnik, David; Davis, Michael R.; Benedetti, Dennis; Moravec, Katie L.; Cywes-Bentley, Colette; Roux, Damien; Traficante, David C.; Walsh, Rebecca L.; Maira-Litràn, Tomas; Cassidy, Sara K.; Hermos, Christina R.; Martin, Thomas R.; Thakkallapalli, Erin L.; Vargas, Sara O.; McAdam, Alexander J.; Lieberman, Tami D.; Kishony, Roy; LiPuma, John J.; Pier, Gerald B.; Goldberg, Joanna B.; Priebe, Gregory P.

    2012-01-01

    Background New therapeutic targets for antibiotic-resistant bacterial pathogens are desperately needed. The bacterial surface polysaccharide poly-β-(1-6)-N-acetyl-glucosamine (PNAG) mediates biofilm formation by some bacterial species, and antibodies to PNAG can confer protective immunity. By analyzing sequenced genomes, we found that potentially multidrug-resistant bacterial species such as Klebsiella pneumoniae, Enterobacter cloacae, Stenotrophomonas maltophilia, and the Burkholderia cepacia complex (BCC) may be able to produce PNAG. Among patients with cystic fibrosis patients, highly antibiotic-resistant bacteria in the BCC have emerged as problematic pathogens, providing an impetus to study the potential of PNAG to be targeted for immunotherapy against pan-resistant bacterial pathogens. Methods The presence of PNAG on BCC was assessed using a combination of bacterial genetics, microscopy, and immunochemical approaches. Antibodies to PNAG were tested using opsonophagocytic assays and for protective efficacy against lethal peritonitis in mice. Results PNAG is expressed in vitro and in vivo by the BCC, and cystic fibrosis patients infected by the BCC species B. dolosa mounted a PNAG-specific opsonophagocytic antibody response. Antisera to PNAG mediated opsonophagocytic killing of BCC and were protective against lethal BCC peritonitis even during coinfection with methicillin-resistant Staphylococcus aureus. Conclusions Our findings raise potential new therapeutic options against PNAG-producing bacteria, including even pan-resistant pathogens. PMID:22448004

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

    PubMed Central

    Plésiat, Patrick

    2015-01-01

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

  10. Multiple resistance to betalactam antibiotics, azithromycin or moxifloxacin in implant associated bacteria.

    PubMed

    Karbach, Julia; Callaway, Angelika S; Willershausen, Brita; Wagner, Wilfried; Al-Nawas, Bilal

    2013-01-01

    Antibiotics are more and more frequently prescribed in dentistry for prevention and treatment of oral diseases. Bacterial resistance to these agents is clearly increasing, including even previously susceptible micro-organisms and true pathogens. The aim of the present investigation was to examine resistant bacterial strains with respect to possible multiple antibiotic resistance. In a previous investigation, implant-associated bacteria were tested first as mixed cultures and again as pure isolates (n = 138) for resistance to one of five antibiotics (ampicillin/AM, ampicillin + sulbactam/AB, azithromycin/AZ, penicillin/PG, moxifloxacin/MX) using the Etest. The resistance of most of the pure isolates was lower than in mixed culture, but 31.2% had retained their original resistance. Subsequently, all 138 isolates were tested for resistance or susceptibility to the other four antibiotics, again using the Etest. 27.6% (38/138) of the isolates retained their original antibiotic resistance and were resistant to at least one other antibiotic (MIC > or = 128 microg/mL for AB, AM or AZ, > or = 32 microg/mL PG, > or = 24 microg/mL MX). 2.2% (3/138) strains had lost their original antibiotic resistance, but were resistant to at least one other antibiotic (MIC > 128 microg/mL for AB, AM, or AZ, > or = 32 microg/mL PG, > or = 24 microg/mL MX). Some of the isolates belonging to the implant-associated microflora were multi-resistant, even though the patients had not received any antibiotics six weeks prior to the sampling. The exact mechanisms that lead to multiple resistance need to be examined in further studies.

  11. The antimicrobial efficacy of silver on antibiotic-resistant bacteria isolated from burn wounds.

    PubMed

    Percival, Steven L; Thomas, John; Linton, Sara; Okel, Tyler; Corum, Linda; Slone, Will

    2012-10-01

    The antibiotic-resistant bacteria are a major concern to wound care because of their ability to resist many of the antibiotics used today to treat infections. Consequently, other antimicrobials, in particular ionic silver, are considered ideal topical agents for effectively helping to manage and prevent local infections. Little is known about the antimicrobial efficacy of ionic silver on antibiotic-resistant bacteria at different pH values. Consequently, in this study our aim was to evaluate the effect of pH on the antimicrobial efficacy of a silver alginate (SA) and a silver carboxymethyl cellulose (SCMC) dressing on antibiotic-resistant bacteria isolated from burn patients. Forty-nine antibiotic-resistant bacteria, including Vancomycin-resistant Enterococcus faecium, meticillin-resistant Staphylococcus aureus, multidrug-resistant (MDR) Pseudomonas aeruginosa, MDR Vibrio sp, MDR Stenotrophomonas maltophilia, extended-spectrum ß-lactamase (ESBL) producing Salmonella sp, ESBL producing Klebsiella pneumoniae, ESBL producing Proteus mirabilis, ESBL producing Escherichia coli and MDR Acinetobacter baumannii, routinely isolated from burn wounds were used in the study and evaluated for their susceptibility to two silver containing wound dressings using a standardised antimicrobial efficacy screening assay [corrected zone of inhibition (CZOI)]. The mean overall CZOI for the Gram-positive isolates at a pH of 5·5 were very similar for both dressings. A mean CZOI of 5 mm was recorded for the SCMC dressing, which was slightly higher, at 5·4 mm for the SA dressing. At a pH of 7·0 both dressings, in general, showed a similar activity. However, at a pH of 8·5 the mean CZOI of the SCMC dressing was found to be significantly (P < 0·05) higher than the SA dressing for a select number of isolates. The mean overall CZOI for the Gram-negative bacteria followed a similar pattern as observed with the Gram-positive bacteria. Susceptibility to silver ions did vary significantly

  12. Occurrence of Multidrug Resistant Extended Spectrum Beta-Lactamase-Producing Bacteria on Iceberg Lettuce Retailed for Human Consumption.

    PubMed

    Bhutani, Natasha; Muraleedharan, Chithra; Talreja, Deepa; Rana, Sonia Walia; Walia, Sandeep; Kumar, Ashok; Walia, Satish K

    2015-01-01

    Antibiotic resistance in bacteria is a global problem exacerbated by the dissemination of resistant bacteria via uncooked food, such as green leafy vegetables. New strains of bacteria are emerging on a daily basis with novel expanded antibiotic resistance profiles. In this pilot study, we examined the occurrence of antibiotic resistant bacteria against five classes of antibiotics on iceberg lettuce retailed in local convenience stores in Rochester, Michigan. In this study, 138 morphologically distinct bacterial colonies from 9 iceberg lettuce samples were randomly picked and tested for antibiotic resistance. Among these isolates, the vast majority (86%) demonstrated resistance to cefotaxime, and among the resistant bacteria, the majority showed multiple drug resistance, particularly against cefotaxime, chloramphenicol, and tetracycline. Three bacterial isolates (2.17%) out of 138 were extended spectrum beta-lactamase (ESBL) producers. Two ESBL producers (T1 and T5) were identified as Klebsiella pneumoniae, an opportunistic pathogen with transferable sulfhydryl variable- (SHV-) and TEM-type ESBLs, respectively. The DNA sequence analysis of the bla SHV detected in K. pneumoniae isolate T1 revealed 99% relatedness to bla SHV genes found in clinical isolates. This implies that iceberg lettuce is a potential reservoir of newly emerging and evolving antibiotic resistant bacteria and its consumption poses serious threat to human health.

  13. Animal antibiotic use has an early but important impact on the emergence of antibiotic resistance in human commensal bacteria

    PubMed Central

    Smith, David L.; Harris, Anthony D.; Johnson, Judith A.; Silbergeld, Ellen K.; Morris, J. Glenn

    2002-01-01

    Antibiotic use is known to promote the development of antibiotic resistance, but substantial controversy exists about the impact of agricultural antibiotic use (AAU) on the subsequent emergence of antibiotic-resistant bacteria among humans. AAU for animal growth promotion or for treatment or control of animal diseases generates reservoirs of antibiotic-resistant (AR) bacteria that contaminate animal food products. Mathematical models are an important tool for understanding the potential medical consequences of this increased exposure. We have developed a mathematical model to evaluate factors affecting the prevalence of human commensal AR bacteria that cause opportunistic infections (e.g., enterococci). Our analysis suggests that AAU hastens the appearance of AR bacteria in humans. Our model indicates that the greatest impact occurs very early in the emergence of resistance, when AR bacteria are rare, possibly below the detection limits of current surveillance methods. PMID:11972035

  14. Analysis on antimicrobial resistance of clinical bacteria isolated from county hospitals and a teaching hospital.

    PubMed

    Sun, Ziyong; Li, Li; Zhu, Xuhui; Ma, Yue; Li, Jingyun; Shen, Zhengyi; Jin, Shaohong

    2006-01-01

    The distinction of antimicrobial resistance of clinical bacteria isolated from county hospitals and a teaching hospital was investigated. Disc diffusion test was used to study the antimicrobial resistance of isolates collected from county hospitals and a teaching hospital. The data was analyzed by WHONET5 and SPSS statistic software. A total of 655 strains and 1682 strains were collected from county hospitals and a teaching hospital, respectively, in the year of 2003. The top ten pathogens were Coagulase negative staphylococci (CNS), E. coli, Klebsiella spp., S. areus, P. aeruginosa, Enterococcus spp., Enterobacter spp., otherwise Salmonella spp., Proteus spp., Shigella spp. in county hospitals and Streptococcus spp., Acinetobacter spp., X. maltophilia in the teaching hospital. The prevalence of multi-drug resistant bacteria was 5% (4/86) of methicillin-resistant S. areus (MRSA), 12% (16/133) and 15.8% (9/57) of extended-spectrum beta-lactamases producing strains of E. coli and Klebsiella spp., respectively, in county hospitals. All of the three rates were lower than that in the teaching hospital and the difference was statistically significant (P < 0. 01). However, the incidence of methicillin-resistant CNS (MRCNS) reached to 70% (109/156) in the two classes of hospitals. Generally, the antimicrobial resistant rates in the county hospitals were lower than those in the teaching hospital, except the resistant rates of ciprofloxacin, erythromycin, clindamycin, SMZco which were similar in the two classes of hospitals. There were differences between county hospitals and the teaching hospital in the distribution of clinical isolates and prevalence of antimicrobial resistance. It was the basis of rational use of antimicrobial agents to monitor antimicrobial resistance by each hospital.

  15. Conjugation between quinolone-susceptible bacteria can generate mutations in the quinolone resistance-determining region, inducing quinolone resistance.

    PubMed

    Pitondo-Silva, André; Martins, Vinicius Vicente; Silva, Carolina Fávero da; Stehling, Eliana Guedes

    2015-02-01

    Quinolones are an important group of antibacterial agents that can inhibit DNA gyrase and topoisomerase IV activity. DNA gyrase is responsible for maintaining bacteria in a negatively supercoiled state, being composed of subunits A and B. Topoisomerase IV is a homologue of DNA gyrase and consists of two subunits codified by the parC and parE genes. Mutations in gyrA and gyrB of DNA gyrase may confer resistance to quinolones, and the majority of resistant strains show mutations between positions 67 and 106 of gyrA, a region denoted the quinolone resistance-determining region (QRDR). The most frequent substitutions occur at positions 83 and 87, but little is known about the mechanisms promoting appearance of mutations in the QRDR. The present study proposes that some mutations in the QRDR could be generated as a result of the natural mechanism of conjugation between bacteria in their natural habitat. This event was observed following conjugation in vitro of two different isolates of quinolone-susceptible Pseudomonas aeruginosa, which transferred plasmids of different molecular weights to a recipient strain of Escherichia coli (HB101), also quinolone-susceptible, generating two different transconjugants that presented mutations in DNA gyrase and acquisition of resistance to all quinolones tested.

  16. Bacteria–bacteria interactions within the microbiota of the ancestral metazoan Hydra contribute to fungal resistance

    PubMed Central

    Fraune, Sebastian; Anton-Erxleben, Friederike; Augustin, René; Franzenburg, Sören; Knop, Mirjam; Schröder, Katja; Willoweit-Ohl, Doris; Bosch, Thomas CG

    2015-01-01

    Epithelial surfaces of most animals are colonized by diverse microbial communities. Although it is generally agreed that commensal bacteria can serve beneficial functions, the processes involved are poorly understood. Here we report that in the basal metazoan Hydra, ectodermal epithelial cells are covered with a multilayered glycocalyx that provides a habitat for a distinctive microbial community. Removing this epithelial microbiota results in lethal infection by the filamentous fungus Fusarium sp. Restoring the complex microbiota in gnotobiotic polyps prevents pathogen infection. Although mono-associations with distinct members of the microbiota fail to provide full protection, additive and synergistic interactions of commensal bacteria are contributing to full fungal resistance. Our results highlight the importance of resident microbiota diversity as a protective factor against pathogen infections. Besides revealing insights into the in vivo function of commensal microbes in Hydra, our findings indicate that interactions among commensal bacteria are essential to inhibit pathogen infection. PMID:25514534

  17. The carriage of antibiotic resistance by enteric bacteria from imported tokay geckos (Gekko gecko) destined for the pet trade.

    PubMed

    Casey, Christine L; Hernandez, Sonia M; Yabsley, Michael J; Smith, Katherine F; Sanchez, Susan

    2015-02-01

    The emergence of antibiotic-resistant bacteria is a growing public health concern and has serious implications for both human and veterinary medicine. The nature of the global economy encourages the movement of humans, livestock, produce, and wildlife, as well as their potentially antibiotic-resistant bacteria, across international borders. Humans and livestock can be reservoirs for antibiotic-resistant bacteria; however, little is known about the prevalence of antibiotic-resistant bacteria harbored by wildlife and, to our knowledge, limited data has been reported for wild-caught reptiles that were specifically collected for the pet trade. In the current study, we examined the antibiotic resistance of lactose-positive Enterobacteriaceae isolates from wild-caught Tokay geckos (Gekko gecko) imported from Indonesia for use in the pet trade. In addition, we proposed that the conditions under which wild animals are captured, transported, and handled might affect the shedding or fecal prevalence of antibiotic resistance. In particular we were interested in the effects of density; to address this, we experimentally modified densities of geckos after import and documented changes in antibiotic resistance patterns. The commensal enteric bacteria from Tokay geckos (G. gecko) imported for the pet trade displayed resistance against some antibiotics including: ampicillin, amoxicillin/clavulanic acid, cefoxitin, chloramphenicol, kanamycin and tetracycline. There was no significant difference in the prevalence of antibiotic-resistant bacteria after experimentally mimicking potentially stressful transportation conditions reptiles experience prior to purchase. There were, however, some interesting trends observed when comparing Tokay geckos housed individually and those housed in groups. Understanding the prevalence of antibiotic resistant commensal enteric flora from common pet reptiles is paramount because of the potential for humans exposed to these animals to acquire antibiotic-resistant

  18. Surveillance of antimicrobial resistance in bacteria isolated from food animals to antimicrobial growth promoters and related therapeutic agents in Denmark.

    PubMed

    Aarestrup, F M; Bager, F; Jensen, N E; Madsen, M; Meyling, A; Wegener, H C

    1998-06-01

    This study was conducted to describe the occurrence of acquired resistance to antimicrobials used for growth promotion among bacteria isolated from swine, cattle and poultry in Denmark. Resistance to structurally related therapeutic agents was also examined. Three categories of bacteria were tested: 1) indicator bacteria (Escherichia coli, Enterococcus faecalis, Enterococcus faecium), 2) zoonotic bacteria (Campylobacter, Salmonella, Yersinia enterocolitica), and 3) animal pathogens (E. coli, Staphylococcus aureus, coagulase-negative staphylococci (CNS), Staphylococcus hyicus, Actinobacillus pleuropneumoniae). All antimicrobials used as growth promoters in Denmark and some structurally related therapeutic agents (in brackets) were included: Avilamycin, avoparcin (vancomycin), bacitracin, carbadox, flavomycin, monensin, olaquindox, salinomycin, spiramycin (erythromycin, lincomycin), tylosin (erythromycin, lincomycin), and virginiamycin (pristinamycin). Bacterial species intrinsically resistant to an antimicrobial were not tested towards that antimicrobial. Breakpoints for growth promoters were established by population distribution of the bacteria tested. A total of 2,372 bacterial isolates collected during October 1995 to September 1996 were included in the study. Acquired resistance to all currently used growth promoting antimicrobials was found. A frequent occurrence of resistance were observed to avilamycin, avoparcin, bacitracin, flavomycin, spiramycin, tylosin and virginiamycin, whereas resistance to carbadox, monensin, olaquindox and salinomycin was less frequent. The occurrence of resistance varied by animal origin and bacterial species. The highest levels of resistance was observed among enterococci, whereas less resistance was observed among zoonotic bacteria and bacteria pathogenic to animals. The association between the occurrence of resistance and the consumption of the antimicrobial is discussed. The results show the present level of resistance to

  19. Occurrence and distribution of antibiotic-resistant bacteria and transfer of resistance genes in Lake Taihu.

    PubMed

    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: bla(TEM) > bla(SHV) > bla(CTMX) 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.

  20. Resistance index of penicillin-resistant bacteria to various physicochemical agents.

    PubMed

    Kazemi, M; Kasra Kermanshahi, R; Heshmat Dehkordi, E; Payami, F; Behjati, M

    2012-01-01

    Widespread use of various antimicrobial agents resulted in the emergence of bacterial resistance. Mechanisms like direct efflux, formation, and sequestration of metals and drugs in complexes and antiporter pumps are some examples. This investigation aims to investigate the resistance pattern of penicillin-resistant bacterial strains to some physicochemical agents. Sensitivity/resistance pattern of common bacterial strains to antimicrobial agents were evaluated by disk diffusion assay. Broth and agar dilution method were used for determination of minimum inhibitory concentration and minimal bactericidal concentration. The impact of UV ray on the bacterial growth under laminar flow hood was measured using photonmeter. Our data demonstrates that the most prevalent metal resistance was against arsenate (95.92%), followed by cadmium (52.04%) and mercury (36.73%). There was significant difference between cetrimide resistances among studied microbial strains especially for P. aeruginosa (P < 0.05). High rate of pathogen resistance to various antibacterial agents in our study supports previously published data. This great rate of bacterial resistance is attributed to the emergence of defense mechanisms developed in pathogens. The higher general bacterial resistance rate among Staphylococcus strains rather than E. coli and P. aeruginosa strains draws attention towards focusing on designing newer therapeutic compounds for Staphylococcus strains.

  1. [Isolation and characterization of two bacteria with heavy metal resistance and phosphate solubilizing capability].

    PubMed

    Tian, Jiang; Peng, Xia-Wei; Li, Xia; Sun, Ya-Jun; Feng, Hong-Mei; Jiang, Ze-Ping

    2014-06-01

    Two phosphate solubilizing bacteria (T PSB1 and T PSB 2) with high heavy metal resistance were isolated from soil of a lead-zinc mine in Huayuan of Hunan Province, China. These two bacteria were identified as Stenotrophomonas maltophilia and Burkholderia gladioli by 16S rRNA sequencing analysis, respectively. In the media containing insoluble inorganic calcium phosphate, the soluble phosphate amounts reached respectively 402.9 mg x L(-1) and 589.9 mg x L(-1) with the bacteria T PSB1 and T PSB2 after two weeks' growth. Moreover, the two bacteria developed solubilizing halos on the plates supplemented with the organic phosphate compounds, and the resulting soluble phosphate amounts in the broth media were respectively 2.97 mg x L(-1) and 4.69 mg x L(-1). In addition, these two bacteria showed the resistance to up to 2000 mg x L(-1) Zn2+, and their phosphate solubilizing amounts reached respectively 114.8 mg x L(-1) and 125.1 mg x L(-1). Similarly, their heavy metal resistance and phosphate solubilizing ability were also found in the Cr and Pb broth media with the concentration of 1000 mg x L(-1). In the Pb media, the soluble phosphate amounts reached respectively 57.9 mg x L(-1) and 71.7 mg x L(-1), and the soluble P amounts in the Cr media were 60.1 mg x L(-1) and 98.4 mg x L(-1) at the concentration of 1000 mg x L(-1).

  2. Antimicrobial Use for and Resistance of Zoonotic Bacteria Recovered from Nonhuman Primates

    PubMed Central

    Kim, Jeffrey; Coble, Dondrae J; Salyards, Gregory W; Bower, Julie K; Rinaldi, William J; Plauche, Gail B; Habing, Gregory G

    2017-01-01

    As a growing threat to human and animal health, antimicrobial resistance (AMR) has become a central public-health topic. Large-scale surveillance systems, such as the National Antimicrobial Resistance Monitoring System (NARMS), are now established to monitor and provide guidance regarding AMR, but comprehensive literature on AMR among NHP is sparse. This study provides data regarding current antimicrobial use strategies and the prevalence of AMR in zoonotic bacteria recovered from NHP within biomedical research institutions. We focused on 4 enteric bacteria: Shigella flexneri, Yersinia enterocolitica, Y. pseudotuberculosis, and Campylobacter jejuni. Fifteen veterinarians, 7 biomedical research institutions, and 4 diagnostic laboratories participated, providing susceptibility test results from January 2012 through April 2015. Veterinarians primarily treated cases caused by S. flexneri, Y. enterocolitica, and Y. pseudotuberculosis with enrofloxacin but treated C. jejuni cases with azithromycin and tylosin. All isolates were susceptible to the associated primary antimicrobial but often showed resistance to others. Specifically, S. flexneri isolates frequently were resistant to erythromycin (87.5%), doxycycline (73.7%), and tetracycline (38.3%); Y. enterocolitica isolates to ampicillin (100%) and cefazolin (93.6%); and C. jejuni isolates to methicillin (99.5%) and cephalothin (97.5%). None of the 58 Y. pseudotuberculosis isolates was resistant to any tested antimicrobial. Notably, resistance patterns were not shared between this study's NHP isolates and human isolates presented by NARMS. Our findings indicate that zoonotic bacteria from NHP diagnostic samples are broadly susceptible to the antimicrobials used to treat the clinical infections. These results can help veterinarians ensure effective antimicrobial therapy and protect staff by minimizing occupational risk. PMID:28222842

  3. Sewage sludge and liquid pig manure as possible sources of antibiotic resistant bacteria.

    PubMed

    Hölzel, Christina S; Schwaiger, Karin; Harms, Katrin; Küchenhoff, Helmut; Kunz, Anne; Meyer, Karsten; Müller, Christa; Bauer, Johann

    2010-05-01

    Within the last decades, the environmental spread of antibiotic resistant bacteria has become a topic of concern. In this study, liquid pig manure (n=305) and sewage sludge (n=111) - used as agricultural fertilizers between 2002 and 2005 - were investigated for the presence of Escherichia coli, Enterococcus faecalis and Enterococcus faecium. Bacteria were tested for their resistance against 40 chemotherapeutics including several "reserve drugs". E. coli (n=613) from pig manure were at a significantly higher degree resistant to streptomycin, doxycycline, spectinomycin, cotrimoxazole, and chloramphenicol than E. coli (n=116) from sewage sludge. Enterococci (Ent. faecalis, n=387, and Ent. faecium, n=183) from pig manure were significantly more often resistant to high levels of doxycycline, rifampicin, erythromycin, and streptomycin than Ent. faecalis (n=44) and Ent. faecium (n=125) from sewage sludge. Significant differences in enterococcal resistance were also seen for tylosin, chloramphenicol, gentamicin high level, fosfomycin, clindamicin, enrofloxacin, moxifloxacin, nitrofurantoin, and quinupristin/dalfopristin. By contrast, aminopenicillins were more effective in enterococci from pig manure, and mean MIC-values of piperacillin+tazobactam and third generation cefalosporines were significantly lower in E. coli from pig manure than in E. coli from sewage sludge. 13.4% (E. coli) to 25.3% (Ent. faecium) of pig manure isolates were high-level multiresistant to substances from more than three different classes of antimicrobial agents. In sewage sludge, high-level-multiresistance reached from 0% (Ent. faecalis) to 16% (Ent. faecium). High rates of (multi-) resistant bacteria in pig manure emphasize the need for a prudent - cautious - use of antibiotics in farm animals.

  4. Antimicrobial Use for and Resistance of Zoonotic Bacteria Recovered from Nonhuman Primates.

    PubMed

    Kim Dondrae J Coble Gregory W Salyards Julie K Bower William J Rinaldi Gail B Plauche And Gregory G Habing, Jeffrey

    2017-01-26

    As a growing threat to human and animal health, antimicrobial resistance (AMR) has become a central public-health topic. Largescale surveillance systems, such as the National Antimicrobial Resistance Monitoring System (NARMS), are now established to monitor and provide guidance regarding AMR, but comprehensive literature on AMR among NHP is sparse. This study provides data regarding current antimicrobial use strategies and the prevalence of AMR in zoonotic bacteria recovered from NHP within biomedical research institutions. We focused on 4 enteric bacteria: Shigella flexneri, Yersinia enterocolitica, Y. pseudotuberculosis,and Campylobacter jejuni. Fifteen veterinarians, 7 biomedical research institutions, and 4 diagnostic laboratories participated, providingsusceptibility test results from January 2012 through April 2015. Veterinarians primarily treated cases caused by S. flexneri,Y. enterocolitica, and Y. pseudotuberculosis with enrofloxacin but treated C. jejuni cases with azithromycin and tylosin. All isolates were susceptible to the associated primary antimicrobial but often showed resistance to others. Specifically, S. flexneri isolates frequently were resistant to erythromycin (87.5%), doxycycline (73.7%), and tetracycline (38.3%); Y. enterocolitica isolates to ampicillin (100%) and cefazolin (93.6%); and C. jejuni isolates to methicillin (99.5%) and cephalothin (97.5%). None of the 58 Y. pseudotuberculosis isolates was resistant to any tested antimicrobial. Notably, resistance patterns were not shared between this study's NHP isolates and human isolates presented by NARMS. Our findings indicate that zoonotic bacteria from NHP diagnostic samples are broadly susceptible to the antimicrobials used to treat the clinical infections. These results can help veterinarians ensure effective antimicrobial therapy and protect staff by minimizing occupational risk.

  5. Antimicrobial Use for and Resistance of Zoonotic Bacteria Recovered from Nonhuman Primates.

    PubMed

    Kim, Jeffrey; Coble, Dondrae J; Salyards, Gregory W; Bower, Julie K; Rinaldi, William J; Plauche, Gail B; Habing, Gregory G

    2017-02-01

    As a growing threat to human and animal health, antimicrobial resistance (AMR) has become a central public-health topic. Largescale surveillance systems, such as the National Antimicrobial Resistance Monitoring System (NARMS), are now established to monitor and provide guidance regarding AMR, but comprehensive literature on AMR among NHP is sparse. This study provides data regarding current antimicrobial use strategies and the prevalence of AMR in zoonotic bacteria recovered from NHP within biomedical research institutions. We focused on 4 enteric bacteria: Shigella flexneri, Yersinia enterocolitica, Y. pseudotuberculosis, and Campylobacter jejuni. Fifteen veterinarians, 7 biomedical research institutions, and 4 diagnostic laboratories participated, providing susceptibility test results from January 2012 through April 2015. Veterinarians primarily treated cases caused by S. flexneri, Y. enterocolitica, and Y. pseudotuberculosis with enrofloxacin but treated C. jejuni cases with azithromycin and tylosin. All isolates were susceptible to the associated primary antimicrobial but often showed resistance to others. Specifically, S. flexneri isolates frequently were resistant to erythromycin (87.5%), doxycycline (73.7%), and tetracycline (38.3%); Y. enterocolitica isolates to ampicillin (100%) and cefazolin (93.6%); and C. jejuni isolates to methicillin (99.5%) and cephalothin (97.5%). None of the 58 Y. pseudotuber-culosis isolates was resistant to any tested antimicrobial. Notably, resistance patterns were not shared between this study's NHP isolates and human isolates presented by NARMS. Our findings indicate that zoonotic bacteria from NHP diagnostic samples are broadly susceptible to the antimicrobials used to treat the clinical infections. These results can help veterinarians ensure effective antimicrobial therapy and protect staff by minimizing occupational risk.

  6. Chemical composition and antibacterial activity of Lavandula coronopifolia essential oil against antibiotic-resistant bacteria.

    PubMed

    Ait Said, L; Zahlane, K; Ghalbane, I; El Messoussi, S; Romane, A; Cavaleiro, C; Salgueiro, L

    2015-01-01

    The aim of this study was to analyse the composition of the essential oil (EO) of Lavandula coronopifolia from Morocco and to evaluate its in vitro antibacterial activity against antibiotic-resistant bacteria isolated from clinical infections. The antimicrobial activity was assessed by a broth micro-well dilution method using multiresistant clinical isolates of 11 pathogenic bacteria: Klebsiella pneumoniae subsp. pneumoniae, Klebsiella ornithinolytica, Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Providencia rettgeri, Citrobacter freundii, Hafnia alvei, Salmonella spp., Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus. The main compounds of the oil were carvacrol (48.9%), E-caryophyllene (10.8%) and caryophyllene oxide (7.7%). The oil showed activity against all tested strains with minimal inhibitory concentration (MIC) values ranging between 1% and 4%. For most of the strains, the MIC value was equivalent to the minimal bactericidal concentration value, indicating a clear bactericidal effect of L. coronopifolia EO.

  7. Prediction of Ionizing Radiation Resistance in Bacteria Using a Multiple Instance Learning Model.

    PubMed

    Aridhi, Sabeur; Sghaier, Haïtham; Zoghlami, Manel; Maddouri, Mondher; Nguifo, Engelbert Mephu

    2016-01-01

    Ionizing-radiation-resistant bacteria (IRRB) are important in biotechnology. In this context, in silico methods of phenotypic prediction and genotype-phenotype relationship discovery are limited. In this work, we analyzed basal DNA repair proteins of most known proteome sequences of IRRB and ionizing-radiation-sensitive bacteria (IRSB) in order to learn a classifier that correctly predicts this bacterial phenotype. We formulated the problem of predicting bacterial ionizing radiation resistance (IRR) as a multiple-instance learning (MIL) problem, and we proposed a novel approach for this purpose. We provide a MIL-based prediction system that classifies a bacterium to either IRRB or IRSB. The experimental results of the proposed system are satisfactory with 91.5% of successful predictions.

  8. [Stress resistance and genetic diversity of endophytic bacteria isolated from Caragana spp. root nodules].

    PubMed

    Dai, Jin-Xia; Wang, Yu-Jiong; Wu, Xue-Juan; Zhang, Xiao-Ling

    2012-02-01

    By adopting PCR-RFLP and 16S rDNA sequencing, this paper analyzed the genetic diversity and phylogeny of 40 endophytic bacterial strains isolated from Caragana spp. root nodules, and determined the salt resistance, acid- and alkali resistance, and growth temperature range of the strains. A total of 9 genotypes were obtained from the 40 strains by RFLP. The 16S rDNA sequencing, morphological observation, and biochemical test of representative strains showed that the strains belonged to Bacillus, Inquilinus, Shinella and Acinetobacter, respectively, and had rich genetic diversity. 57.5% of the strains could tolerate 4% NaCl stress, 75% of the strains could grow in YMA medium with an initial pH 11.0, and 85% of the strains could survive after heat shock treatment at 60 degrees C, suggesting that the endophytic bacteria of Caragana spp. had strong resistance capacity. Among the strains, LWEN 07 and LWEN 15 were most resistant.

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

    PubMed Central

    Stickler, D J; Thomas, B

    1980-01-01

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

  10. Curing bacteria of antibiotic resistance: reverse antibiotics, a novel class of antibiotics in nature.

    PubMed

    Hiramatsu, Keiichi; Igarashi, Masayuki; Morimoto, Yuh; Baba, Tadashi; Umekita, Maya; Akamatsu, Yuzuru

    2012-06-01

    By screening cultures of soil bacteria, we re-discovered an old antibiotic (nybomycin) as an antibiotic with a novel feature. Nybomycin is active against quinolone-resistant Staphylococcus aureus strains with mutated gyrA genes but not against those with intact gyrA genes against which quinolone antibiotics are effective. Nybomycin-resistant mutant strains were generated from a quinolone-resistant, nybomycin-susceptible, vancomycin-intermediate S. aureus (VISA) strain Mu 50. The mutants, occurring at an extremely low rate (<1 × 10(-11)/generation), were found to have their gyrA genes back-mutated and to have lost quinolone resistance. Here we describe nybomycin as the first member of a novel class of antibiotics designated 'reverse antibiotics'.

  11. Synergistic effects of antimicrobial peptide DP7 combined with antibiotics against multidrug-resistant bacteria.

    PubMed

    Wu, Xiaozhe; Li, Zhan; Li, Xiaolu; Tian, Yaomei; Fan, Yingzi; Yu, Chaoheng; Zhou, Bailing; Liu, Yi; Xiang, Rong; Yang, Li

    2017-01-01

    Antibiotic-resistant bacteria present a great threat to public health. In this study, the synergistic effects of antimicrobial peptides (AMPs) and antibiotics on several multidrug-resistant bacterial strains were studied, and their synergistic effects on azithromycin (AZT)-resistance genes were analyzed to determine the relationships between antimicrobial resistance and these synergistic effects. A checkerboard method was used to evaluate the synergistic effects of AMPs (DP7 and CLS001) and several antibiotics (gentamicin, vancomycin [VAN], AZT, and amoxicillin) on clinical bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli). The AZT-resistance genes (ermA, ermB, ermC, mefA, and msrA) were identified in the resistant strains using quantitative polymerase chain reaction. For all the clinical isolates tested that were resistant to different antibiotics, DP7 had high antimicrobial activity (≤32 mg/L). When DP7 was combined with VAN or AZT, the effect was most frequently synergistic. When we studied the resistance genes of the AZT-resistant isolates, the synergistic effect of DP7-AZT occurred most frequently in highly resistant strains or strains carrying more than two AZT-resistance genes. A transmission electron microscopic analysis of the S. aureus strain synergistically affected by DP7-AZT showed no noteworthy morphological changes, suggesting that a molecular-level mechanism plays an important role in the synergistic action of DP7-AZT. AMP DP7 plus the antibiotic AZT or VAN is more effective, especially against highly antibiotic-resistant strains.

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

    PubMed Central

    Louie, Arnold; MacGowan, Alasdair; Hope, William

    2015-01-01

    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. PMID:26711759

  13. Synergistic effects of antimicrobial peptide DP7 combined with antibiotics against multidrug-resistant bacteria

    PubMed Central

    Wu, Xiaozhe; Li, Zhan; Li, Xiaolu; Tian, Yaomei; Fan, Yingzi; Yu, Chaoheng; Zhou, Bailing; Liu, Yi; Xiang, Rong; Yang, Li

    2017-01-01

    Antibiotic-resistant bacteria present a great threat to public health. In this study, the synergistic effects of antimicrobial peptides (AMPs) and antibiotics on several multidrug-resistant bacterial strains were studied, and their synergistic effects on azithromycin (AZT)-resistance genes were analyzed to determine the relationships between antimicrobial resistance and these synergistic effects. A checkerboard method was used to evaluate the synergistic effects of AMPs (DP7 and CLS001) and several antibiotics (gentamicin, vancomycin [VAN], AZT, and amoxicillin) on clinical bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli). The AZT-resistance genes (ermA, ermB, ermC, mefA, and msrA) were identified in the resistant strains using quantitative polymerase chain reaction. For all the clinical isolates tested that were resistant to different antibiotics, DP7 had high antimicrobial activity (≤32 mg/L). When DP7 was combined with VAN or AZT, the effect was most frequently synergistic. When we studied the resistance genes of the AZT-resistant isolates, the synergistic effect of DP7–AZT occurred most frequently in highly resistant strains or strains carrying more than two AZT-resistance genes. A transmission electron microscopic analysis of the S. aureus strain synergistically affected by DP7–AZT showed no noteworthy morphological changes, suggesting that a molecular-level mechanism plays an important role in the synergistic action of DP7–AZT. AMP DP7 plus the antibiotic AZT or VAN is more effective, especially against highly antibiotic-resistant strains. PMID:28356719

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

    PubMed Central

    Hope, William; MacGowan, Alasdair; Louie, Arnold

    2015-01-01

    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. PMID:26711766

  15. Fluoroquinolone-Resistant Enteric Bacteria in Sub-Saharan Africa: Clones, Implications and Research Needs

    PubMed Central

    Chattaway, Marie A.; Aboderin, Aaron O.; Fashae, Kayode; Okoro, Chinyere K.; Opintan, Japheth A.; Okeke, Iruka N.

    2016-01-01

    Fluoroquinolones came into widespread use in African countries in the early 2000s, after patents for the first generation of these drugs expired. By that time, quinolone antibacterial agents had been used intensively worldwide and resistant lineages of many bacterial species had evolved. We sought to understand which Gram negative enteric pandemic lineages have been reported from Africa, as well as the nature and transmission of any indigenous resistant clones. A systematic review of articles indexed in the Medline and AJOL literature databases was conducted. We report on the findings of 43 eligible studies documenting local or pandemic fluoroquinolone-resistant enteric clones in sub-Sahara African countries. Most reports are of invasive non-typhoidal Salmonella and Escherichia coli lineages and there have been three reports of cholera outbreaks caused by fluoroquinolone-resistant Vibrio cholerae O1. Fluoroquinolone-resistant clones have also been reported from commensals and animal isolates but there are few data for non-Enterobacteriaceae and almost none for difficult-to-culture Campylobacter spp. Fluoroquinolone-resistant lineages identified in African countries were universally resistant to multiple other classes of antibacterial agents. Although as many as 972 non-duplicate articles refer to fluoroquinolone resistance in enteric bacteria from Africa, most do not report on subtypes and therefore information on the epidemiology of fluoroquinolone-resistant clones is available from only a handful of countries in the subcontinent. When resistance is reported, resistance mechanisms and lineage information is rarely investigated. Insufficient attention has been given to molecular and sequence-based methods necessary for identifying and tracking resistant clones in Africa and more research is needed in this area. PMID:27148238

  16. Fluoroquinolone-Resistant Enteric Bacteria in Sub-Saharan Africa: Clones, Implications and Research Needs.

    PubMed

    Chattaway, Marie A; Aboderin, Aaron O; Fashae, Kayode; Okoro, Chinyere K; Opintan, Japheth A; Okeke, Iruka N

    2016-01-01

    Fluoroquinolones came into widespread use in African countries in the early 2000s, after patents for the first generation of these drugs expired. By that time, quinolone antibacterial agents had been used intensively worldwide and resistant lineages of many bacterial species had evolved. We sought to understand which Gram negative enteric pandemic lineages have been reported from Africa, as well as the nature and transmission of any indigenous resistant clones. A systematic review of articles indexed in the Medline and AJOL literature databases was conducted. We report on the findings of 43 eligible studies documenting local or pandemic fluoroquinolone-resistant enteric clones in sub-Sahara African countries. Most reports are of invasive non-typhoidal Salmonella and Escherichia coli lineages and there have been three reports of cholera outbreaks caused by fluoroquinolone-resistant Vibrio cholerae O1. Fluoroquinolone-resistant clones have also been reported from commensals and animal isolates but there are few data for non-Enterobacteriaceae and almost none for difficult-to-culture Campylobacter spp. Fluoroquinolone-resistant lineages identified in African countries were universally resistant to multiple other classes of antibacterial agents. Although as many as 972 non-duplicate articles refer to fluoroquinolone resistance in enteric bacteria from Africa, most do not report on subtypes and therefore information on the epidemiology of fluoroquinolone-resistant clones is available from only a handful of countries in the subcontinent. When resistance is reported, resistance mechanisms and lineage information is rarely investigated. Insufficient attention has been given to molecular and sequence-based methods necessary for identifying and tracking resistant clones in Africa and more research is needed in this area.

  17. Arsenic resistance genes of As-resistant purple nonsulfur bacteria isolated from As-contaminated sites for bioremediation application.

    PubMed

    Nookongbut, Phitthaya; Kantachote, Duangporn; Krishnan, Kannan; Megharaj, Mallavarapu

    2017-04-01

    This study aimed to identify arsenic resistant mechanisms in As-resistant purple nonsulfur bacteria (PNSB) by screening them for presence of As-resistance genes and related enzymes. Resistance to As(III) and As(V) of four As-resistant PNSB determined in terms of median inhibition concentration (IC50 values) were in the order of strains Rhodopseudomonas palustris C1 > R. palustris AB3 > Rubrivivax benzoatilyticus C31 > R. palustris L28 which corresponded to the presence of As-resistance genes in these bacteria. The strain C1 showed all As-marker genes; arsC, arsM, aioA, and acr3, while aioA was not detected in strain AB3. Strains C31 and L28 had only Arsenite-transporter gene, acr3. Translation of all these detected gene sequences of strain C1 to amino acid sequences showed that these proteins have vicinal cysteine; Cys126, Cys105, and Cys178 of Acr3, ArsC, AioA, respectively. Tertiary structure of proteins Acr3, ArsC, AioA, and ArsM showed strain C1 exhibits the high activities of arsenite oxidase and arsenate reductase enzymes that are encoded by aioA and arsC genes, respectively. Moreover, strain C1 with arsM gene produced volatile-methylated As-compounds; monomethylarsonic acid (MMA), dimethylarsenic acid (DMA), and arsenobetaine (AsB) in the presence of either As(III) or As(V). In conclusion, the strain C1 has great potential for its application in bioremediation of As-contaminated sites.

  18. Reprogrammable microbial cell-based therapeutics against antibiotic-resistant bacteria.

    PubMed

    Hwang, In Young; Koh, Elvin; Kim, Hye Rim; Yew, Wen Shan; Chang, Matthew Wook

    2016-07-01

    The discovery of antimicrobial drugs and their subsequent use has offered an effective treatment option for bacterial infections, reducing morbidity and mortality over the past 60 years. However, the indiscriminate use of antimicrobials in the clinical, community and agricultural settings has resulted in selection for multidrug-resistant bacteria, which has led to the prediction of possible re-entrance to the pre-antibiotic era. The situation is further exacerbated by significantly reduced antimicrobial drug discovery efforts by large pharmaceutical companies, resulting in a steady decline in the number of new antimicrobial agents brought to the market in the past several decades. Consequently, there is a pressing need for new antimicrobial therapies that can be readily designed and implemented. Recently, it has become clear that the administration of broad-spectrum antibiotics can lead to collateral damage to the human commensal microbiota, which plays several key roles in host health. Advances in genetic engineering have opened the possibility of reprogramming commensal bacteria that are in symbiotic existence throughout the human body to implement antimicrobial drugs with high versatility and efficacy against pathogenic bacteria. In this review, we discuss recent advances and potentialities of engineered bacteria in providing a novel antimicrobial strategy against antibiotic resistance. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    PubMed Central

    2013-01-01

    Background In response to the propagation of bacteria resistant to many antibiotics also called multi-drug resistant (MDR) bacteria, the discovery of new and more efficient antibacterial agents is primordial. The present study was aimed at evaluating the antibacterial activities of seven Cameroonian dietary plants (Adansonia digitata, Aframomum alboviolaceum, Aframomum polyanthum, Anonidium. mannii, Hibiscus sabdarifa, Ocimum gratissimum and Tamarindus indica). Methods The phytochemical screening of the studied extracts was performed using described methods whilst the liquid broth micro dilution was used for all antimicrobial assays against 27 Gram-negative bacteria. Results The results of the phytochemical tests indicate that all tested extracts contained phenols and triterpenes, other classes of chemicals being selectively present. The studied extracts displayed various degrees of antibacterial activities. The extracts of A. digitata, H. sabdarifa, A. polyanthum, A. alboviolaceum and O. gratissimum showed the best spectra of activity, their inhibitory effects being recorded against 81.48%, 66.66%, 62.96%, 55.55%, and 55.55% of the 27 tested bacteria respectively. The extract of A. polyanthum was very active against E. aerogenes EA294 with the lowest recorded minimal inhibitory concentration (MIC) of 32 μg/ml. Conclusion The results of the present work provide useful baseline information for the potential use of the studied edible plants in the fight against both sensitive and MDR phenotypes. PMID:23837916

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

    PubMed

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

    2013-07-10

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

  1. Characteristics of Hg-resistant bacteria isolated from Minamata Bay sediment

    SciTech Connect

    Nakamura, K.; Fujisaki, T.; Tamashiro, H.

    1986-06-01

    Seventy-two strains of Hg-resistant bacteria (Pseudomonas) were isolated on agar plates containing 40 micrograms/ml of HgCl2 from Minamata Bay sediment, which was heavily polluted with mercury (45.8 micrograms/g). The minimal inhibitory concentrations (MICs) of mercurial compounds were determined for the Hg-resistant pseudomonads and 65 strains (Pseudomonas sp., Bacillus sp., Vibrio sp., and Corynebacterium sp.) isolated from Sendai Bay sediment (1 microgram/g of mercury) as control. The MICs to HgCl/sub 2/, CH/sub 3/HgCl, C/sub 2/H/sub 5/HgCl, C/sub 3/H/sub 7/HgCl, and C/sub 6/H/sub 5/HgOCOCH/sub 3/ for the Hg-resistant pseudomonads from Minamata Bay were significantly higher than those of strains from Sendai Bay. The volatilization from liquid culture containing 20 micrograms/ml of HgCl2 was observed in all of the Hg-resistant pseudomonads from Minamata Bay (70 strains). The mean loss of mercury from liquid culture was 60.4 +/- 17.3%. Further study is warranted to determine what role the Hg-resistant bacteria, particularly the Pseudomonas species, play in the mercury cycle in Minamata Bay.

  2. Role of Mn2+ and Compatible Solutes in the Radiation Resistance of Thermophilic Bacteria and Archaea

    PubMed Central

    Webb, Kimberly M.; DiRuggiero, Jocelyne

    2012-01-01

    Radiation-resistant bacteria have garnered a great deal of attention from scientists seeking to expose the mechanisms underlying their incredible survival abilities. Recent analyses showed that the resistance to ionizing radiation (IR) in the archaeon Halobacterium salinarum is dependent upon Mn-antioxidant complexes responsible for the scavenging of reactive oxygen species (ROS) generated by radiation. Here we examined the role of the compatible solutes trehalose, mannosylglycerate, and di-myo-inositol phosphate in the radiation resistance of aerobic and anaerobic thermophiles. We found that the IR resistance of the thermophilic bacteria Rubrobacter xylanophilus and Rubrobacter radiotolerans was highly correlated to the accumulation of high intracellular concentration of trehalose in association with Mn, supporting the model of Mn2+-dependent ROS scavenging in the aerobes. In contrast, the hyperthermophilic archaea Thermococcus gammatolerans and Pyrococcus furiosus did not contain significant amounts of intracellular Mn, and we found no significant antioxidant activity from mannosylglycerate and di-myo-inositol phosphate in vitro. We therefore propose that the low levels of IR-generated ROS under anaerobic conditions combined with highly constitutively expressed detoxification systems in these anaerobes are key to their radiation resistance and circumvent the need for the accumulation of Mn-antioxidant complexes in the cell. PMID:23209374

  3. Antibiotic-resistant bacteria associated with retail aquaculture products from Guangzhou, China.

    PubMed

    Ye, Lei; Lu, Zhang; Li, Xinhui; Shi, Lei; Huang, Ying; Wang, Hua H

    2013-02-01

    This study examined the prevalence of antibiotic-resistant (ART) bacteria and representative antibiotic resistance (AR)-encoding genes associated with several aquaculture products from retail markets in Guangzhou, China. ART commensal bacteria were found in 100% of the products examined. Among 505 multidrug-resistant isolates examined, close to one-fourth contained intI and sul1 genes: 15% contained sul2 and 5% contained tet (E). Incidences of β-lactamase-encoding genes bla(TEM), bla(CMY) and erythromycin resistance determinants ermB and ermC were 4.5, 1.7, 1.3, and 0.3%, respectively. Most of the ART isolates identified from the rinse water were Aeromonas spp.; those from intestines belonged to the Enterobacteriaceae. Plasmid-associated intI and AR-encoding genes were identified in several ART isolates by Southern hybridization. Three multidrug resistance-encoding plasmids were transferred into Escherichia coli DH5 a by chemical transformation and led to acquired AR in the transformants. In addition, the AR traits in many isolates were quite stable, even in the absence of selective pressure. Further studies are needed to reveal risk factors associated with the aquaculture production chain for targeted AR mitigation.

  4. Role of Mn2+ and compatible solutes in the radiation resistance of thermophilic bacteria and archaea.

    PubMed

    Webb, Kimberly M; DiRuggiero, Jocelyne

    2012-01-01

    Radiation-resistant bacteria have garnered a great deal of attention from scientists seeking to expose the mechanisms underlying their incredible survival abilities. Recent analyses showed that the resistance to ionizing radiation (IR) in the archaeon Halobacterium salinarum is dependent upon Mn-antioxidant complexes responsible for the scavenging of reactive oxygen species (ROS) generated by radiation. Here we examined the role of the compatible solutes trehalose, mannosylglycerate, and di-myo-inositol phosphate in the radiation resistance of aerobic and anaerobic thermophiles. We found that the IR resistance of the thermophilic bacteria Rubrobacter xylanophilus and Rubrobacter radiotolerans was highly correlated to the accumulation of high intracellular concentration of trehalose in association with Mn, supporting the model of Mn(2+)-dependent ROS scavenging in the aerobes. In contrast, the hyperthermophilic archaea Thermococcus gammatolerans and Pyrococcus furiosus did not contain significant amounts of intracellular Mn, and we found no significant antioxidant activity from mannosylglycerate and di-myo-inositol phosphate in vitro. We therefore propose that the low levels of IR-generated ROS under anaerobic conditions combined with highly constitutively expressed detoxification systems in these anaerobes are key to their radiation resistance and circumvent the need for the accumulation of Mn-antioxidant complexes in the cell.

  5. Assessment and characterization of heavy metal resistance in Palk Bay sediment bacteria.

    PubMed

    Nithya, Chari; Gnanalakshmi, Balasubramanian; Pandian, Shunmugiah Karutha

    2011-05-01

    The present study aimed at characterizing the heavy metal resistance and assessing the resistance pattern to multiple heavy metals (300 mmol L⁻¹) by Palk Bay sediment bacteria. From 46 isolates, 24 isolates showed resistance to more than eight heavy metals. Among the 24 isolates S8-06 (Bacillus arsenicus), S8-10 (Bacillus pumilus), S8-14 (B. arsenicus), S6-01 (Bacillus indicus), S6-04 (Bacillus clausii), SS-06 (Planococcus maritimus) and SS-08 (Staphylococcus pasteuri) exhibited high resistance against arsenic, mercury, cobalt, cadmium, lead and selenium. Plasmid curing confirmed that the heavy metal resistance in S8-10 is chromosomal borne. Upon treatment with the heavy metals, the strain S8-10 showed many morphological and physiological changes as shown by SEM, FTIR and AAS analysis. S8-10 removed 47% of cadmium and 96% of lead from the growth medium. The study suggests that sediment bacteria can be biological indicators of heavy metal contamination.

  6. Multi-resistant bacteria in spontaneous bacterial peritonitis: A new step in management?

    PubMed Central

    de Mattos, Angelo Alves; Costabeber, Ane Micheli; Lionço, Livia Caprara; Tovo, Cristiane Valle

    2014-01-01

    Spontaneous bacterial peritonitis (SBP) is the most typical infection observed in cirrhosis patients. SBP is responsible for an in-hospital mortality rate of approximately 32%. Recently, pattern changes in the bacterial flora of cirrhosis patients have been observed, and an increase in the prevalence of infections caused by multi-resistant bacteria has been noted. The wide-scale use of quinolones in the prophylaxis of SBP has promoted flora modifications and resulted in the development of bacterial resistance. The efficacy of traditionally recommended therapy has been low in nosocomial infections (up to 40%), and multi-resistance has been observed in up to 22% of isolated germs in nosocomial SBP. For this reason, the use of a broad empirical spectrum antibiotic has been suggested in these situations. The distinction between community-acquired infectious episodes, healthcare-associated infections, or nosocomial infections, and the identification of risk factors for multi-resistant germs can aid in the decision-making process regarding the empirical choice of antibiotic therapy. Broad-spectrum antimicrobial agents, such as carbapenems with or without glycopeptides or piperacillin-tazobactam, should be considered for the initial treatment not only of nosocomial infections but also of healthcare-associated infections when the risk factors or severity signs for multi-resistant bacteria are apparent. The use of cephalosporins should be restricted to community-acquired infections. PMID:25339797

  7. Assessment of copper and zinc salts as selectors of antibiotic resistance in Gram-negative bacteria.

    PubMed

    Becerra-Castro, Cristina; Machado, Rita A; Vaz-Moreira, Ivone; Manaia, Célia M

    2015-10-15

    Some metals are nowadays considered environmental pollutants. Although some, like Cu and Zn, are essential for microorganisms, at high concentrations they can be toxic or exert selective pressures on bacteria. This study aimed to assess the potential of Cu or Zn as selectors of specific bacterial populations thriving in wastewater. Populations of Escherichia coli recovered on metal-free and metal-supplemented culture medium were compared based on antibiotic resistance phenotype and other traits. In addition, the bacterial groups enriched after successive transfers in metal-supplemented culture medium were identified. At a concentration of 1mM, Zn produced a stronger inhibitory effect than Cu on the culturability of Enterobacteriaceae. It was suggested that Zn selected populations with increased resistance prevalence to sulfamethoxazole or ciprofloxacin. In non-selective culture media, Zn or Cu selected for mono-species populations of ubiquitous Betaproteobacteria and Flavobacteriia, such as Ralstonia pickettii or Elizabethkingia anophelis, yielding multidrug resistance profiles including resistance against carbapenems and third generation cephalosporins, confirming the potential of Cu or Zn as selectors of antibiotic resistant bacteria.

  8. Colistin Use in Neonates and Children With Infections Due to Carbapenem-resistant Bacteria.

    PubMed

    Antachopoulos, Charalampos; Iosifidis, Elias

    2017-09-01

    Current evidence on the use of colistin in pediatric patients for infections caused by carbapenem-resistant bacteria is based on retrospective case series. The coadministration of colistin with other antimicrobial agents was associated with a relatively low rate of nephrotoxicity and a favorable outcome in >70% of these patients. Further study of colistin pharmacokinetics in children and neonates will likely lead to optimization of dosage recommendations.

  9. Thermodynamic Analysis of the Lipopolysaccharide-Dependent Resistance of Gram-Negative Bacteria against Polymyxin B

    PubMed Central

    Howe, Jörg; Andrä, Jörg; Conde, Raquel; Iriarte, Maite; Garidel, Patrick; Koch, Michel H. J.; Gutsmann, Thomas; Moriyón, Ignacio; Brandenburg, Klaus

    2007-01-01

    Cationic antimicrobial cationic peptides (CAMP) have been found in recent years to play a decisive role in hosts' defense against microbial infection. They have also been investigated as a new therapeutic tool, necessary in particular due to the increasing resistance of microbiological populations to antibiotics. The structural basis of the activity of CAMPs has only partly been elucidated and may comprise quite different mechanism at the site of the bacterial cell membranes or in their cytoplasm. Polymyxin B (PMB) is a CAMP which is effective in particular against Gram-negative bacteria and has been well studied with the aim to understand its interaction with the outer membrane or isolated membrane components such as lipopolysaccharide (LPS) and to define the mechanism by which the peptides kill bacteria or neutralize LPS. Since PMB resistance of bacteria is a long-known phenomenon and is attributed to structural changes in the LPS moiety of the respective bacteria, we have performed a thermodynamic and biophysical analysis to get insights into the mechanisms of various LPS/PMB interactions in comparison to LPS from sensitive strains. In isothermal titration calorimetric (ITC) experiments considerable differences of PMB binding to sensitive and resistant LPS were found. For sensitive LPS the endothermic enthalpy change in the gel phase of the hydrocarbon chains converts into an exothermic reaction in the liquid crystalline phase. In contrast, for resistant LPS the binding enthalpy change remains endothermic in both phases. As infrared data show, these differences can be explained by steric changes in the headgroup region of the respective LPS. PMID:17237210

  10. Inoculation of Lens culinaris with Pb-resistant bacteria shows potential for phytostabilization.

    PubMed

    Jebara, Salwa Harzalli; Saadani, Omar; Fatnassi, Imen Challougui; Chiboub, Manel; Abdelkrim, Souhir; Jebara, Moez

    2015-02-01

    Phytoremediation comprises a set of plant and microbe-based technologies for remediation of soil heavy metal contamination. In this work, four Pb-resistant bacteria (Agrobacterium tumefaciens, Rahnella aquatilis, and two Pseudomonas sp.) were selected among a collection of isolates from root nodule of Lens culinaris. They had a high degree of bioaccumulation ability in nutrient medium containing 2 mM Pb, and the maximum Pb accumulation of whole cell was found after 48-h incubation. These Pb-resistant bacteria synthesized plant growth promoting substances such as indole acetic acid and siderophore. The presence of the Pb resistance genes (pbrA) in these bacteria has been confirmed by PCR. L. culinaris cultivated in two experimental soils with different levels of contamination showed that Pb contamination affected plant growth; therefore, it's co-inoculation with the consortium of Pb-resistant bacteria improved plant biomass. The present study demonstrated that lentil accumulated Pb primarily in their roots and poorly in their shoots; in addition, it's co-inoculation in moderately Pb-contaminated soil induced a reduction in Pb accumulation in roots and shoots by 22 and 80 %, respectively. Whereas in highly Pb-contaminated soil, we registered a diminution in concentration of Pb in shoots (66 %) and an augmentation in roots (21 %). The contamination of soil by Pb caused an oxidative stress in lentil plant, inducing modulation in antioxidant enzymes activities, essentially in superoxide dismutase (SOD) and peroxidase (GPOX) activities which were more pronounced in lentil cultivated in highly Pb-contaminated soil, in addition, co-inoculation enhanced these activities, suggesting the protective role of enzymatic antioxidant against Pb-induced plant stress.Thus, the present study demonstrated that co-inoculation of lentil with A. tumefaciens, R. aquatilis, and Pseudomonas sp. formed a symbiotic system useful for phytostabilization of highly and moderately Pb

  11. Ecological study on antimicrobial-resistant zoonotic bacteria transmitted by flies in cattle farms.

    PubMed

    Mohammed, Asmaa N; Abdel-Latef, Gihan K; Abdel-Azeem, Naglaa M; El-Dakhly, Khaled Mohamed

    2016-10-01

    Flies were qualitatively and quantitatively monitored on both livestock animals and the surrounding environment to investigate their role as a potential carrier for antimicrobial-resistant bacteria of zoonotic importance in cattle farms. This was done by the use of visual observations and animal photography; meanwhile, in the surrounding environment, flies were collected using sticky cards and then microscopically identified. Representative fly samples were cultured for bacterial isolation, biochemical identification, and then tested against common 12 antibiotics. The total average of dipterous flies in examined farms was 400.42 ± 6.2. Culicoides biting midges were the most common existing species (70.01 %) followed by house flies, stable flies, and mosquitoes (18.31, 7.74, and 3.91 %, respectively) at X (2) = 9.0, P < 0.05. The most predominant bacterial isolates were Escherichia coli (22.6 %), Staphylococcus aureus and Enterobacter (17.3 % each), coagulase-negative Staphylococci (CNS) (14.7 %), Klebsiella sp. (8 %), Salmonella spp. (6.7 %), and Shigella spp. and Proteus spp. (6.7 % each). The tested bacterial isolates were resistant to variant antibiotics used. S. aureus exhibited 100 % resistance to colistine. However, E. coli revealed 92.9 and 78.6 % resistance against tetracycline and colistine, respectively. Both Salmonella spp. and Shigella spp. were 100 % resistant to penicillin, and Klebsiella sp. had 100 % resistance to tetracycline. In conclusion, Culicoides biting midges and house flies could be considered as a potential carrier for multi-drug-resistant bacteria of zoonotic importance. Furthermore, cows' environment has an essential role in propagation and wide spread of antimicrobial-resistant bacterial pathogens.

  12. Thermotolerance and multidrug resistance in bacteria isolated from equids and their environment.

    PubMed

    Singh, B R

    2009-06-13

    Sixty-nine vaginal swabs and 138 rectal swabs collected from 195 equids were analysed for the presence of thermotolerant bacteria, that is, bacteria surviving at 60+/-0.1 degrees C for one hour. Thermotolerant Escherichia coli, Enterobacter species, Klebsiella pneumoniae, Proteus species and Pseudomonas species were isolated from 41, 16, nine, three and three of the 138 rectal swabs, respectively; seven of the E coli and two of the Enterobacter species isolates survived pasteurisation at 63.8+/-0.1 degrees C for 30 minutes. All except three E coli, two Enterobacter species and one Proteus species isolate were resistant to three or more antimicrobial drugs, that is, they were multidrug resistant. Thermotolerant E coli, Enterobacter species and Proteus species were isolated from 11, two and two of the 69 vaginal swabs, respectively, but only one isolate of E coli survived pasteurisation at 63.8+/-0.1 degrees C for 30 minutes. All except two of the E coli isolates were multidrug resistant. None of the four thermotolerant isolates from nine soil samples collected on four of the farms where the equids were kept was pasteurisation resistant, but they were all multidrug resistant. Of the 10 pasteurisation-resistant isolates, nine were multidrug resistant but none was resistant to chloramphenicol, ciprofloxacin, cotrimazine, cotrimoxazole or streptomycin. All the isolates grew at 42+/-0.1 degrees C but none grew at 46+/-0.1 degrees C or above. The Enterobacter isolates were more tolerant to pasteurisation than the E coli isolates, particularly during the first few minutes of exposure.

  13. Transmission dynamics of resistant bacteria in a predator-prey system.

    PubMed

    Gao, Xubin; Pan, Qiuhui; He, Mingfeng

    2015-01-01

    This paper discusses the impact on human health caused by the addition of antibiotics in the feed of food animals. We use the established transmission rule of resistant bacteria and combine it with a predator-prey system to determine a differential equations model. The equations have three steady equilibrium points corresponding to three population dynamics states under the influence of resistant bacteria. In order to quantitatively analyze the stability of the equilibrium points, we focused on the basic reproduction numbers. Then, both the local and global stability of the equilibrium points were quantitatively analyzed by using essential mathematical methods. Numerical results are provided to relate our model properties to some interesting biological cases. Finally, we discuss the effect of the two main parameters of the model, the proportion of antibiotics added to feed and the predation rate, and estimate the human health impacts related to the amount of feed antibiotics used. We further propose an approach for the prevention of the large-scale spread of resistant bacteria and illustrate the necessity of controlling the amount of in-feed antibiotics used.

  14. Synergistic Antimicrobial Activity of Camellia sinensis and Juglans regia against Multidrug-Resistant Bacteria

    PubMed Central

    Farooqui, Amber; Khan, Adnan; Borghetto, Ilaria; Kazmi, Shahana U.; Rubino, Salvatore; Paglietti, Bianca

    2015-01-01

    Synergistic combinations of antimicrobial agents with different mechanisms of action have been introduced as more successful strategies to combat infections involving multidrug resistant (MDR) bacteria. In this study, we investigated synergistic antimicrobial activity of Camellia sinensis and Juglans regia which are commonly used plants with different antimicrobial agents. Antimicrobial susceptibility of 350 Gram-positive and Gram-negative strains belonging to 10 different bacterial species, was tested against Camellia sinensis and Juglans regia extracts. Minimum inhibitory concentrations (MICs) were determined by agar dilution and microbroth dilution assays. Plant extracts were tested for synergistic antimicrobial activity with different antimicrobial agents by checkerboard titration, Etest/agar incorporation assays, and time kill kinetics. Extract treated and untreated bacteria were subjected to transmission electron microscopy to see the effect on bacterial cell morphology. Camellia sinensis extract showed higher antibacterial activity against MDR S. Typhi, alone and in combination with nalidixic acid, than to susceptible isolates.” We further explore anti-staphylococcal activity of Juglans regia that lead to the changes in bacterial cell morphology indicating the cell wall of Gram-positive bacteria as possible target of action. The synergistic combination of Juglans regia and oxacillin reverted oxacillin resistance of methicillin resistant Staphylococcus aureus (MRSA) strains in vitro. This study provides novel information about antimicrobial and synergistic activity of Camellia sinensis and Juglans regia against MDR pathogens PMID:25719410

  15. Potential Emergence of Multi-quorum Sensing Inhibitor Resistant (MQSIR) Bacteria.

    PubMed

    Koul, Shikha; Prakash, Jyotsana; Mishra, Anjali; Kalia, Vipin Chandra

    2016-03-01

    Expression of certain bacterial genes only at a high bacterial cell density is termed as quorum-sensing (QS). Here bacteria use signaling molecules to communicate among themselves. QS mediated genes are generally involved in the expression of phenotypes such as bioluminescence, biofilm formation, competence, nodulation, and virulence. QS systems (QSS) vary from a single in Vibrio spp. to multiple in Pseudomonas and Sinorhizobium species. The complexity of QSS is further enhanced by the multiplicity of signals: (1) peptides, (2) acyl-homoserine lactones, (3) diketopiperazines. To counteract this pathogenic behaviour, a wide range of bioactive molecules acting as QS inhibitors (QSIs) have been elucidated. Unlike antibiotics, QSIs don't kill bacteria and act at much lower concentration than those of antibiotics. Bacterial ability to evolve resistance against multiple drugs has cautioned researchers to develop QSIs which may not generate undue pressure on bacteria to develop resistance against them. In this paper, we have discussed the implications of the diversity and multiplicity of QSS, in acting as an arsenal to withstand attack from QSIs and may use these as reservoirs to develop multi-QSI resistance.

  16. Surface-mediated chromate-resistant mechanism of Enterobacter cloacae bacteria investigated by atomic force microscopy.

    PubMed

    Yang, Chunpeng; Cheng, Yangjian; Ma, Xiaoyan; Zhu, Ying; Holman, Hoi-Ying; Lin, Zhang; Wang, Chen

    2007-04-10

    The Enterobacter cloacae CYS-25 strain isolated from a chromate plant shows a strong capability for chromate resistance instead of chromate reduction in aerobic conditions. In this study, atomic force microscopy (AFM) was used for studying the morphology characteristics of bacterial properties during the chromate resistance process. The average length of E. cloacae bacteria in the stationary phase is about 2.3 +/- 0.6 microm, while under the stimulation of 400 mg/L CrO42-, the length of bacteria increases to 3.2 +/- 0.7 microm. Height and phase images showed that, with the addition of CrO42-, the smooth surface of bacteria changed into one with discontinuous features with characteristic dimension of 40-200 nm. Analysis reveals that these compact convex patches are organic components stimulated by CrO42-. A chromate resistance mechanism relating to the overexpression of extracellular biologic components for preventing the permeability of CrO42- into the cell is proposed as the survival strategy of E. cloacae in chromate situation.

  17. Synergistic antimicrobial activity of Camellia sinensis and Juglans regia against multidrug-resistant bacteria.

    PubMed

    Farooqui, Amber; Khan, Adnan; Borghetto, Ilaria; Kazmi, Shahana U; Rubino, Salvatore; Paglietti, Bianca

    2015-01-01

    Synergistic combinations of antimicrobial agents with different mechanisms of action have been introduced as more successful strategies to combat infections involving multidrug resistant (MDR) bacteria. In this study, we investigated synergistic antimicrobial activity of Camellia sinensis and Juglans regia which are commonly used plants with different antimicrobial agents. Antimicrobial susceptibility of 350 Gram-positive and Gram-negative strains belonging to 10 different bacterial species, was tested against Camellia sinensis and Juglans regia extracts. Minimum inhibitory concentrations (MICs) were determined by agar dilution and microbroth dilution assays. Plant extracts were tested for synergistic antimicrobial activity with different antimicrobial agents by checkerboard titration, Etest/agar incorporation assays, and time kill kinetics. Extract treated and untreated bacteria were subjected to transmission electron microscopy to see the effect on bacterial cell morphology. Camellia sinensis extract showed higher antibacterial activity against MDR S. Typhi, alone and in combination with nalidixic acid, than to susceptible isolates." We further explore anti-staphylococcal activity of Juglans regia that lead to the changes in bacterial cell morphology indicating the cell wall of Gram-positive bacteria as possible target of action. The synergistic combination of Juglans regia and oxacillin reverted oxacillin resistance of methicillin resistant Staphylococcus aureus (MRSA) strains in vitro. This study provides novel information about antimicrobial and synergistic activity of Camellia sinensis and Juglans regia against MDR pathogens.

  18. Azithromycin, fluoroquinolone and chloramphenicol resistance of non-chlamydia conjunctival bacteria in rural community of Ethiopia

    PubMed Central

    Abera, Bayeh; Kibret, Mulugeta

    2014-01-01

    Aim: To determine profiles of non-chlamydia conjunctival bacteria and their antimicrobial susceptibility from adults who underwent trachomatous trichiasis surgery in rural areas of Ethiopia. Materials and Methods: A cross-sectional study was conducted in rural districts in West Gojjam administrative zone. Conjunctival swabs were collected during surgery and transported using Stuart transport broth (Oxoid, UK). Antibiotic susceptibility of conjunctival isolates was determined using the Kirby-Bauer disc-diffusion method. Results: Non-chlamydia pathogenic bacteria were recovered from conjunctiva of 438 (31%) participants before treatment. The isolated conjunctival bacteria were Staphylococcus aureus, coagulase-negative Staphylococci, Streptococcus group (A, C, F and G), Enterococci, Streptococcus pneumoniae, Moraxella spp., Escherichia coli, Citrobacter spp., Proteus spp., Klebsiella spp., Pseudomonas spp. and Enterobacter spp. Overall, resistance rates of 57.8% to azithromycin and 68.5% to chloramphenicol were found. However, 86-94.4% sensitivity was demonstrated to ciprofloxacin and norfloxacin. Moderate sensitivity rates (61.8-78.4%) were observed to ceftriaxone, tetracycline and cotrimoxazole. Conclusion: Fluoroquinolones that have activity against the majority of bacterial isolates were potent at in vitro. However, unacceptably high levels of resistance to azithromycin and chloramphenicol in rural community indicated a need for further study and antimicrobial resistance surveillance. PMID:23571246

  19. Photodynamic inactivation of multidrug-resistant bacteria in hospital wastewaters: influence of residual antibiotics.

    PubMed

    Almeida, Joana; Tomé, João P C; Neves, Maria G P M S; Tomé, Augusto C; Cavaleiro, José A S; Cunha, Ângela; Costa, Liliana; Faustino, Maria A F; Almeida, Adelaide

    2014-04-01

    One environmental concern related to hospital effluents is discharge of them without preliminary treatment. Antimicrobial photodynamic inactivation (PDI) may represent an alternative to the traditional expensive, unsafe and not always effective disinfection methods. The main goal of this work was to assess the efficiency of PDI on clinical multidrug-resistant (MDR) bacteria in hospital wastewaters in order to evaluate its potential use in treating hospital effluents. The efficiency of PDI was assessed using a cationic porphyrin as the photosensitizer (PS), four MDR bacteria either in phosphate buffered saline or in filtrated hospital wastewaters. The synergistic effect of PDI and antibiotics (ampicillin and chloramphenicol) was also evaluated, as well as the effect of the surfactant sodium dodecyl sulfate (SDS). The results show the efficient inactivation of MDR bacteria in PBS (reduction of 6-8 log after 270 min of irradiation at 40 W m(-2) with 5.0 μM of PS). In wastewater, the inactivation of the four MDR bacteria was again efficient and the decrease in bacterial survival starts even sooner. A faster decrease in bacterial survival occurred when PDI was combined with the addition of antibiotics, at sub-inhibitory and inhibitory concentrations, but the SDS did not affect the PDI efficiency. It can be concluded that PDI has potential to be an effective alternative for the inactivation of MDR bacteria in hospital wastewaters and that the presence of antibiotics may enhance its effectiveness.

  20. New biodiagnostics based on optical tweezers: typing red blood cells, and identification of drug resistant bacteria

    NASA Astrophysics Data System (ADS)

    Chen, Jia-Wen; Lin, Chuen-Fu; Wang, Shyang-Guang; Lee, Yi-Chieh; Chiang, Chung-Han; Huang, Min-Hui; Lee, Yi-Hsiung; Vitrant, Guy; Pan, Ming-Jeng; Lee, Horng-Mo; Liu, Yi-Jui; Baldeck, Patrice L.; Lin, Chih-Lang

    2013-09-01

    Measurements of optical tweezers forces on biological micro-objects can be used to develop innovative biodiagnostics methods. In the first part of this report, we present a new sensitive method to determine A, B, D types of red blood cells. Target antibodies are coated on glass surfaces. Optical forces needed to pull away RBC from the glass surface increase when RBC antigens interact with their corresponding antibodies. In this work, measurements of stripping optical forces are used to distinguish the major RBC types: group O Rh(+), group A Rh(+) and group B Rh(+). The sensitivity of the method is found to be at least 16-folds higher than the conventional agglutination method. In the second part of this report, we present an original way to measure in real time the wall thickness of bacteria that is one of the most important diagnostic parameters of bacteria drug resistance in hospital diagnostics. The optical tweezers force on a shell bacterium is proportional to its wall thickness. Experimentally, we determine the optical tweezers force applied on each bacteria family by measuring their escape velocity. Then, the wall thickness of shell bacteria can be obtained after calibrating with known bacteria parameters. The method has been successfully applied to indentify, from blind tests, Methicillinresistant Staphylococcus aureus (MRSA), including VSSA (NCTC 10442), VISA (Mu 50), and heto-VISA (Mu 3)

  1. Antimicrobial resistance genes in marine bacteria and human uropathogenic Escherichia coli from a region of intensive aquaculture.

    PubMed

    Tomova, Alexandra; Ivanova, Larisa; Buschmann, Alejandro H; Rioseco, Maria Luisa; Kalsi, Rajinder K; Godfrey, Henry P; Cabello, Felipe C

    2015-10-01

    Antimicrobials are heavily used in Chilean salmon aquaculture. We previously found significant differences in antimicrobial-resistant bacteria between sediments from an aquaculture and a non-aquaculture site. We now show that levels of antimicrobial resistance genes (ARG) are significantly higher in antimicrobial-selected marine bacteria than in unselected bacteria from these sites. While ARG in tetracycline- and florfenicol-selected bacteria from aquaculture and non-aquaculture sites were equally frequent, there were significantly more plasmid-mediated quinolone resistance genes per bacterium and significantly higher numbers of qnrB genes in quinolone-selected bacteria from the aquaculture site. Quinolone-resistant urinary Escherichia coli from patients in the Chilean aquacultural region were significantly enriched for qnrB (including a novel qnrB gene), qnrS, qnrA and aac(6')-1b, compared with isolates from New York City. Sequences of qnrA1, qnrB1 and qnrS1 in quinolone-resistant Chilean E. coli and Chilean marine bacteria were identical, suggesting horizontal gene transfer between antimicrobial-resistant marine bacteria and human pathogens. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  2. Effect of Tetracycline Dose and Treatment Mode on Selection of Resistant Coliform Bacteria in Nursery Pigs.

    PubMed

    Græsbøll, Kaare; Damborg, Peter; Mellerup, Anders; Herrero-Fresno, Ana; Larsen, Inge; Holm, Anders; Nielsen, Jens Peter; Christiansen, Lasse Engbo; Angen, Øystein; Ahmed, Shahana; Folkesson, Anders; Olsen, John Elmerdahl

    2017-06-15

    This study describes the results of a randomized clinical trial investigating the effect of oxytetracycline treatment dose and mode of administration on the selection of antibiotic-resistant coliform bacteria in fecal samples from nursery pigs. Nursery pigs (pigs of 4 to 7 weeks of age) in five pig herds were treated with oxytetracycline for Lawsonia intracellularis-induced diarrhea. Each group was randomly allocated to one of five treatment groups: oral flock treatment with a (i) high (20 mg/kg of body weight), (ii) medium (10 mg/kg), or (iii) low (5 mg/kg) dose, (iv) oral pen-wise (small-group) treatment (10 mg/kg), and (v) individual intramuscular injection treatment (10 mg/kg). All groups were treated once a day for 5 days. In all groups, treatment caused a rise in the numbers and proportions of tetracycline-resistant coliform bacteria right after treatment, followed by a significant drop by the time that the pigs left the nursery unit. The counts and proportions of tetracycline-resistant coliforms did not vary significantly between treatment groups, except immediately after treatment, when the highest treatment dose resulted in the highest number of resistant coliforms. A control group treated with tiamulin did not show significant changes in the numbers or proportions of tetracycline-resistant coliforms. Selection for tetracycline-resistant coliforms was significantly correlated to selection for ampicillin- and sulfonamide-resistant strains but not to selection for cefotaxime-resistant strains. In conclusion, the difference in the dose of oxytetracycline and the way in which the drug was applied did not cause significantly different levels of selection of tetracycline-resistant coliform bacteria under the conditions tested.IMPORTANCE Antimicrobial resistance is a global threat to human health. Treatment of livestock with antimicrobials has a direct impact on this problem, and there is a need to improve the ways that we use antimicrobials in livestock

  3. Use of natural antimicrobials to increase antibiotic susceptibility of drug resistant bacteria.

    PubMed

    Palaniappan, Kavitha; Holley, Richard A

    2010-06-15

    Plant-derived antibacterial compounds may be of value as a novel means for controlling antibiotic resistant zoonotic pathogens which contaminate food animals and their products. Individual activity of natural antimicrobials (eugenol, thymol, carvacrol, cinnamaldehyde, allyl isothiocyanate (AIT)) and activity when paired with an antibiotic was studied using broth microdilution and checkerboard methods. In the latter assays, fractional inhibitory concentration (FIC) values were calculated to characterize interactions between the inhibitors. Bacteria tested were chosen because of their resistance to at least one antibiotic which had a known genetic basis. Substantial susceptibility of these bacteria toward the natural antimicrobials and a considerable reduction in the minimum inhibitory concentrations (MIC's) of the antibiotics were noted when paired combinations of antimicrobial and antibiotic were used. In the interaction study, thymol and carvacrol were found to be highly effective in reducing the resistance of Salmonella Typhimurium SGI 1 (tet A) to ampicillin, tetracycline, penicillin, bacitracin, erythromycin and novobiocin (FIC<0.4) and resistance of Streptococcus pyogenes ermB to erythromycin (FIC<0.5). With Escherichia coli N00 666, thymol and cinnamaldehyde were found to have a similar effect (FIC<0.4) in reducing the MIC's of ampicillin, tetracycline, penicillin, erythromycin and novobiocin. Carvacrol, thymol (FIC<0.3) and cinnamaldehyde (FIC<0.4) were effective against Staphylococcus aureus blaZ and in reducing the MIC's of ampicillin, penicillin and bacitracin. Allyl isothiocyanate (AIT) was effective in reducing the MIC of erythromycin (FIC<0.3) when tested against S. pyogenes. Fewer combinations were found to be synergistic when the decrease in viable population (log DP) was calculated. Together, fractional inhibitory concentrations < or = 0.5 and log DP<-1 indicated synergistic action between four natural antimicrobials and as many as three antibiotics

  4. The fate of carbapenem-resistant bacteria in a wastewater treatment plant.

    PubMed

    Hrenovic, Jasna; Ivankovic, Tomislav; Ivekovic, Damir; Repec, Sinisa; Stipanicev, Drazenka; Ganjto, Marin

    2017-09-22

    Wastewater treatment plants have been considered potential sources of antibiotic resistance gene exchange and release into the environment. The aim of our study was to quantify environmental and human-associated carbapenem-resistant bacterial populations (CRBPs) across wastewater treatment stages and correlate bacterial counts to physicochemical and other bacteriological parameters in order to see their behaviour in wastewater and sludge and their potential dissemination in the environment. Samples were taken from five sites (treatment stages) of the largest Croatian wastewater treatment plant (20 per site) over 10 months of monitoring. CRBPs were found at all wastewater treatment stages save for the lime-treated, stabilised sludge, which underlines the importance of effluent and digested sludge disinfection. Secondary sludge settling removed 99% of CRBP from the effluent, but the relative proportion of CRBP in the total bacterial count significantly increased in the effluent (0.0020%) and digested sludge (0.0019%) compared to the influent (0.0006%), indicating selection for resistant bacteria in these settings. CRBP counts did not correlate with measured carbapenem concentrations in wastewater, which suggests that antibiotic concentrations were not the reason for CRBP selection. Negative correlation between activated sludge retention time and CRBP indicated that their number could be reduced by increasing the retention time during secondary treatment. Despite the indications that WWTPs select for antibiotic-resistant bacteria, wastewater treatment is very efficient in reducing their absolute numbers, and proper effluent and sludge disinfection can significantly reduce dissemination of antibiotic-resistant bacteria into the environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Human recreational exposure to antibiotic resistant bacteria in coastal bathing waters.

    PubMed

    Leonard, Anne F C; Zhang, Lihong; Balfour, Andrew J; Garside, Ruth; Gaze, William H

    2015-09-01

    Infections caused by antibiotic resistant bacteria (ARB) are associated with poor health outcomes and are recognised globally as a serious health problem. Much research has been conducted on the transmission of ARB to humans. Yet the role the natural environment plays in the spread of ARB and antibiotic resistance genes is not well understood. Antibiotic resistant bacteria have been detected in natural aquatic environments, and ingestion of seawater during water sports is one route by which many people could be directly exposed. The aim was to estimate the prevalence of resistance to one clinically important class of antibiotics (third-generation cephalosporins (3GCs)) amongst Escherichia coli in coastal surface waters in England and Wales. Prevalence data was used to quantify ingestion of 3GC-resistant E. coli (3GCREC) by people participating in water sports in designated coastal bathing waters. A further aim was to use this value to derive a population-level estimate of exposure to these bacteria during recreational use of coastal waters in 2012. The prevalence of 3GC-resistance amongst E. coli isolated from coastal surface waters was estimated using culture-based methods. This was combined with the density of E. coli reported in designated coastal bathing waters along with estimations of the volumes of water ingested during various water sports reported in the literature to calculate the mean number of 3GCREC ingested during different water sports. 0.12% of E. coli isolated from surface waters were resistant to 3GCs. This value was used to estimate that in England and Wales over 6.3 million water sport sessions occurred in 2012 that resulted in the ingestion of at least one 3GCREC. Despite the low prevalence of resistance to 3GCs amongst E. coli in surface waters, there is an identifiable human exposure risk for water users, which varies with the type of water sport undertaken. The relative importance of this exposure is likely to be greater in areas where a

  6. The inhibitory effect of Zingiber corallinum Hance essential oil on drug-resistant bacteria and evaluation of its acute toxicity

    PubMed Central

    Yang, Ce; Zhou, Lin-Lin; Wang, Hai-Yan; Huang, Su-Na; Liu, Qing; Hu, Shi-Lin; Li, Ting-Rong; Chen, Yan-Bing; Jiang, Jian-Xin

    2011-01-01

    Summary Background The excessive and irregular use of antibiotics could result in the generation and diffusion of drug-resistant bacteria. The aim of this study was to investigate the inhibitory effect of Zingiber corallinum Hance essential oil (ZCHO) on drug-resistant bacteria, especially on drug-resistant Acinetobacter baumannii. Material/Methods Susceptibility testing was used to evaluate the effect of ZCHO on growth inhibition of drug-resistant bacteria by paper disk method. Mice orally administered with ZCHO were used to observe acute toxicity and to determine median lethal dose (LD50) of ZCHO. Broth dilution method was used to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ZCHO on drug-resistant Acinetobacter baumannii. Results ZCHO exhibited an obvious inhibitory effect not only on gram-negative drug-resistant bacteria including Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae and Acinetobacter baumannii, but also on gram-positive drug-resistant bacteria including Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus haemolyticus. The ZCHO containing 79% terpinen-4-ol revealed better bacteriostatic effect than ZCHO with 34% terpinen-4-ol. The LD50 of ZCHO was 1790.427 mg/kg. The MIC and MBC of ZCHO on drug-resistant Acinetobacter baumannii were 1457.81 mg/L. Conclusions ZCHO has obvious bacteriostasis and bactericidal effects, especially against drug-resistant Acinetobacter baumannii. Therefore, ZCHO is a promising natural bioactive component with antibacterial effect and satisfactory safety due to its low toxicity. PMID:21525802

  7. Incidence and transferability of antibiotic resistance in the enteric bacteria isolated from hospital wastewater

    PubMed Central

    Alam, Mohammad Zubair; Aqil, Farrukh; Ahmad, Iqbal; Ahmad, Shamim

    2013-01-01

    This study reports the occurrence of antibiotic resistance and production of β-lactamases including extended spectrum beta-lactamases (ESβL) in enteric bacteria isolated from hospital wastewater. Among sixty-nine isolates, tested for antibiotic sensitivity, 73.9% strains were resistant to ampicillin followed by nalidixic acid (72.5%), penicillin (63.8%), co-trimoxazole (55.1%), norfloxacin (53.6%), methicillin (52.7%), cefuroxime (39.1%), cefotaxime (23.2%) and cefixime (20.3%). Resistance to streptomycin, chloramphenicol, nitrofurantoin, tetracycline, and doxycycline was recorded in less than 13% of the strains. The minimum inhibitory concentration (MIC) showed a high level of resistance (800–1600 μg/mL) to one or more antibiotics. Sixty three (91%) isolates produced β-lactamases as determined by rapid iodometric test. Multiple antibiotic resistances were noted in both among ESβL and non-ESβL producers. The β-lactamases hydrolyzed multiple substrates including penicillin (78.8% isolates), ampicillin (62.3%), cefodroxil (52.2%), cefotoxime (21.7%) and cefuroxime (18.8%). Fifteen isolates producing ESβLs were found multidrug resistant. Four ESβL producing isolates could transfer their R-plasmid to the recipient strain E. coli K-12 with conjugation frequency ranging from 7.0 × 10−3 to 8.8 × 10−4. The findings indicated that ESβL producing enteric bacteria are common in the waste water. Such isolates may disseminate the multiple antibiotic resistance traits among bacterial community through genetic exchange mechanisms and thus requires immediate attention. PMID:24516448

  8. Antibiotic resistance among bacteria isolated from seawater and penguin fecal samples collected near Palmer Station, Antarctica.

    PubMed

    Miller, Robert V; Gammon, Katharine; Day, Martin J

    2009-01-01

    Antibiotic resistance in aquatic bacteria has increased steadily as a consequence of the widespread use of antibiotics, but practice and international treaty should have limited antibiotic contamination in Antarctica. We estimated antibiotic resistance in microorganisms isolated from the Antarctic marine waters and a penguin rookery, for 2 reasons: (i) as a measure of human impact and (ii) as a potential "snapshot" of the preantibiotic world. Samples were taken at 4 established sampling sites near Palmer Station, which is situated at the southern end of the Palmer Archipelago (64 degrees 10'S, 61 degrees 50'W). Sites were chosen to provide different potentials for human contamination. Forty 50 mL samples of seawater were collected and colony-forming units (CFU)/mL were determined at 6 and 20 degrees C. For this study, presumed psychrophiles (growth at 6 degrees C) were assumed to be native to Antarctic waters, whereas presumed mesophiles (growth at 20 degrees C but not at 6 degrees C) were taken to represent introduced organisms. The 20-6 degrees C CFU/mL ratio was used as a measure of the relative impact to the ecosystem of presumably introduced organisms. This ratio was highest at the site nearest to Palmer Station and decreased with distance from it, suggesting that human presence has impacted the natural microbial flora of the site. The frequency of resistance to 5 common antibiotics was determined in each group of isolates. Overall drug resistance was higher among the presumed mesophiles than the presumed psychrophiles and increased with proximity to Palmer Station, with the presumed mesophiles showing higher frequencies of single and multiple drug resistance than the psychrophile population. The frequency of multidrug resistance followed the same pattern. It appears that multidrug resistance is low among native Antarctic bacteria but is increased by human habitation.

  9. Incidence and transferability of antibiotic resistance in the enteric bacteria isolated from hospital wastewater.

    PubMed

    Alam, Mohammad Zubair; Aqil, Farrukh; Ahmad, Iqbal; Ahmad, Shamim

    2013-01-01

    This study reports the occurrence of antibiotic resistance and production of β-lactamases including extended spectrum beta-lactamases (ESβL) in enteric bacteria isolated from hospital wastewater. Among sixty-nine isolates, tested for antibiotic sensitivity, 73.9% strains were resistant to ampicillin followed by nalidixic acid (72.5%), penicillin (63.8%), co-trimoxazole (55.1%), norfloxacin (53.6%), methicillin (52.7%), cefuroxime (39.1%), cefotaxime (23.2%) and cefixime (20.3%). Resistance to streptomycin, chloramphenicol, nitrofurantoin, tetracycline, and doxycycline was recorded in less than 13% of the strains. The minimum inhibitory concentration (MIC) showed a high level of resistance (800-1600 μg/mL) to one or more antibiotics. Sixty three (91%) isolates produced β-lactamases as determined by rapid iodometric test. Multiple antibiotic resistances were noted in both among ESβL and non-ESβL producers. The β-lactamases hydrolyzed multiple substrates including penicillin (78.8% isolates), ampicillin (62.3%), cefodroxil (52.2%), cefotoxime (21.7%) and cefuroxime (18.8%). Fifteen isolates producing ESβLs were found multidrug resistant. Four ESβL producing isolates could transfer their R-plasmid to the recipient strain E. coli K-12 with conjugation frequency ranging from 7.0 × 10(-3) to 8.8 × 10(-4). The findings indicated that ESβL producing enteric bacteria are common in the waste water. Such isolates may disseminate the multiple antibiotic resistance traits among bacterial community through genetic exchange mechanisms and thus requires immediate attention.

  10. Metal and antibiotic resistance of bacteria isolated from the Baltic Sea.

    PubMed

    Moskot, Marta; Kotlarska, Ewa; Jakóbkiewicz-Banecka, Joanna; Gabig-Cimińska, Magdalena; Fari, Karolina; Wegrzyn, Grzegorz; Wróbel, Borys

    2012-09-01

    The resistance of 49 strains of bacteria isolated from surface Baltic Sea waters to 11 antibiotics was analyzed and the resistance of selected strains to three metal ions (Ni2+, Mn2+, Zn2+) was tested. Most isolates belonged to Gammaproteobacteria (78%), while Alphaproteobacteria (8%), Actinobacteria (10%), and Bacteroidetes (4%) were less abundant. Even though previous reports suggested relationships between resistance and the presence of plasmids or the ability to produce pigments, no compelling evidence for such relationships was obtained for the strains isolated in this work. In particular, strains resistant to multiple antibiotics did not carry plasmids more frequently than sensitive strains. A relation between resistance and the four aminoglycosides tested (gentamycin, kanamycin, neomycin, and streptomycin), but not to spectinomycin, was demonstrated. This observation is of interest given that spectinomycin is not always classified as an aminoglycoside because it lacks a traditional sugar moiety. Statistical analysis indicated relationships between resistance to some antibiotics (ampicillin and erythromycin, chloramphenicol and erythromycin, chloramphenicol and tetracycline, erythromycin and tetracycline), suggesting the linkage of resistance genes for antibiotics belonging to different classes. The effects of NiSO4, ZnCl2 and MnCl2 on various media suggested that the composition of Marine Broth might result in low concentrations of Mn2+ due to chemical interactions that potentially lead to precipitation.

  11. Multidrug-resistant bacteria among patients with ventilatorassociated pneumonia in an emergency intensive care unit, Egypt.

    PubMed

    Azzab, Magda M; El-Sokkary, Rehab H; Tawfeek, Mohamed M; Gebriel, Manar G

    2017-02-01

    Ventilator-associated pneumonia (VAP) is the most common hospital-acquired infection among mechanically ventilated patients. Our objectives were to determine the incidence of VAP, isolate multidrug-resistant bacteria, identify the most prevalent resistant strains and identify their antibiotic susceptibility pattern. The VAP rate was calculated. The isolated microbes were identified and tested for antibiotic susceptibilities. The minimum inhibitory concentrations were determined of imipenem, meropenem and ertapenem for Klebsiella isolates. Klebsiella isolates resistant to carbapenems were tested for the presence of the blaKPC gene. The VAP incidence density rate was 48.8 incidences/1 000 ventilator days. The most common Gram-positive organism was Staphylococcus aureus, of which 86.6% of isolates were resistant to cefoxitin , but 100% were sensitive to teicoplanin, linezolid and tigecycline. The most common Gram-negative bacillus was Klebsiella, of which 94.6% of isolates were resistant to cefotaxime, 70.2% to imipenem, and 64.9% to ertapenem, but 100% were sensitive to colistin and 94.6% were sensitive to tigecycline. Of the carbapenem-resistant Klebsiella strains, 23.1% had the blaKPC gene. The high rates of VAP and the high rates of resistance among isolated organisms point to improper implementation of infection control programmes.

  12. Enhanced antibiotic multi-resistance in nasal and faecal bacteria after agricultural use of streptomycin

    PubMed Central

    Scherer, Alexandre; Vogt, Hans-Rudolf; Vilei, Edy M; Frey, Joachim; Perreten, Vincent

    2013-01-01

    Streptomycin is used in arboriculture to control fire blight. Using sheep as a model, multidrug-resistant bacteria in mammals were found to be selected after the intentional release of streptomycin into the environment. Escherichia coli and Staphylococcus spp. were isolated from the faeces and nasal cavities, respectively, of sheep grazing on a field sprayed with streptomycin at concentrations used in orchards (test group) and on a field without streptomycin (control group). Before the application of streptomycin, the percentage of streptomycin-resistant E. coli isolates in faeces was 15.8% in the control group and 14.7% in the test group. After the application of streptomycin, the overall number of streptomycin-resistant E. coli isolates was significantly higher in the test group (39.9%) than in the control group (22.3%). Streptomycin-resistant Staphylococcus isolates were only detected after the application of streptomycin. Streptomycin resistance was frequently associated with resistance to sulfamethoxazole, ampicillin, tetracycline and chloramphenicol and less frequently to cefotaxime in E. coli, and to tetracycline, fusidic acid and tiamulin in Staphylococcus spp. This study shows that the application of low concentrations of streptomycin on grass, as occurs during the spraying of orchards, selects for multidrug-resistant nasal and enteric bacterial flora, including extended-spectrum beta-lactamase-producing E. coli. PMID:23157680

  13. Multiple antibiotic-resistant bacteria on fluted pumpkin leaves, a herb of therapeutic value.

    PubMed

    Igbeneghu, Oluwatoyin A; Abdu, Abdulrasheed B

    2014-06-01

    Fluted pumpkin (Telfairia occidentalis) is a minimally-processed green leafy vegetable traditionally used for its antianaemic properties in the form of leaf juice without a heating or inactivation step before consumption. The aim of the study was to assess the presence of surface microbiota on T. occidentalis leaves and also to determine the antimicrobial susceptibility of isolated organisms. Bacterial contaminants on 50 samples of T. occidentalis leaves were isolated and characterized using standard biochemical methods and the antimicrobial susceptibility of isolated organisms was determined using the antibiotic disc diffusion assay. The results obtained show that the leaves of T. occidentalis is contaminated with organisms which included Enterobacter agglomerans (25.9%), Proteus vulgaris (24.9%), Klebsiella spp. (2.6%), and Serratia liquefaciens (2.1%). Other bacterial isolates recovered in order of frequency included: Staphylococcus spp. (33.7%), Bacillus spp. (8.3%), and Pseudomonas fluorescens (2.6%). Of the 193 bacterial isolates from the leaves of T. occidentalis samples tested for antimicrobial resistance, all (100%) were found to be resistant to ampicillin, cloxacillin, augmentin, erythromycin, and tetracycline while 96% of the isolates were resistant to cephalothin. Resistance to trimethoprim (93%) and gentamicin (83%) was also observed. Approximately, 22% of the isolates were resistant to ciprofloxacin; however, only 11 (5.8%) were resistant to ofloxacin. Thus, uncooked T. occidentalis is a potential source of highly-resistant epiphytic bacteria which could be opportunistic pathogens in consumers.

  14. Multiple Antibiotic-resistant Bacteria on Fluted Pumpkin Leaves, a Herb of Therapeutic Value

    PubMed Central

    Abdu, Abdulrasheed B.

    2014-01-01

    ABSTRACT Fluted pumpkin (Telfairia occidentalis) is a minimally-processed green leafy vegetable traditionally used for its antianaemic properties in the form of leaf juice without a heating or inactivation step before consumption. The aim of the study was to assess the presence of surface microbiota on T. occidentalis leaves and also to determine the antimicrobial susceptibility of isolated organisms. Bacterial contaminants on 50 samples of T. occidentalis leaves were isolated and characterized using standard biochemical methods and the antimicrobial susceptibility of isolated organisms was determined using the antibiotic disc diffusion assay. The results obtained show that the leaves of T. occidentalis is contaminated with organisms which included Enterobacter agglomerans (25.9%), Proteus vulgaris (24.9%), Klebsiella spp. (2.6%), and Serratia liquefaciens (2.1%). Other bacterial isolates recovered in order of frequency included: Staphylococcus spp. (33.7%), Bacillus spp. (8.3%), and Pseudomonas fluorescens (2.6%). Of the 193 bacterial isolates from the leaves of T. occidentalis samples tested for antimicrobial resistance, all (100%) were found to be resistant to ampicillin, cloxacillin, augmentin, erythromycin, and tetracycline while 96% of the isolates were resistant to cephalothin. Resistance to trimethoprim (93%) and gentamicin (83%) was also observed. Approximately, 22% of the isolates were resistant to ciprofloxacin; however, only 11 (5.8%) were resistant to ofloxacin. Thus, uncooked T. occidentalis is a potential source of highly-resistant epiphytic bacteria which could be opportunistic pathogens in consumers. PMID:25076655

  15. The emerging threat of multidrug-resistant Gram-negative bacteria in urology.

    PubMed

    Zowawi, Hosam M; Harris, Patrick N A; Roberts, Matthew J; Tambyah, Paul A; Schembri, Mark A; Pezzani, M Diletta; Williamson, Deborah A; Paterson, David L

    2015-10-01

    Antibiotic resistance in Gram-negative uropathogens is a major global concern. Worldwide, the prevalence of Enterobacteriaceae that produce extended-spectrum β-lactamase or carbapenemase enzymes continues to increase at alarming rates. Likewise, resistance to other antimicrobial agents including aminoglycosides, sulphonamides and fluoroquinolones is also escalating rapidly. Bacterial resistance has major implications for urological practice, particularly in relation to catheter-associated urinary tract infections (UTIs) and infectious complications following transrectal-ultrasonography-guided biopsy of the prostate or urological surgery. Although some new drugs with activity against Gram-negative bacteria with highly resistant phenotypes will become available in the near future, the existence of a single agent with activity against the great diversity of resistance is unlikely. Responding to the challenges of Gram-negative resistance will require a multifaceted approach including considered use of current antimicrobial agents, improved diagnostics (including the rapid detection of resistance) and surveillance, better adherence to basic measures of infection prevention, development of new antibiotics and research into non-antibiotic treatment and preventive strategies.

  16. CIPROFLOXACIN RESISTANCE PATTERN AMONG BACTERIA ISOLATED FROM PATIENTS WITH COMMUNITY-ACQUIRED URINARY TRACT INFECTION.

    PubMed

    Reis, Ana Carolina Costa; Santos, Susana Regia da Silva; Souza, Siane Campos de; Saldanha, Milena Góes; Pitanga, Thassila Nogueira; Oliveira, Ricardo Riccio

    2016-07-11

    To identify the main bacterial species associated with community-acquired urinary tract infection (UTI) and to assess the pattern of ciprofloxacin susceptibility among bacteria isolated from urine cultures. We conducted a retrospective study in all the patients with community-acquired UTI seen in Santa Helena Laboratory, Camaçari, Bahia, Brazil during five years (2010-2014). All individuals who had a positive urine culture result were included in this study. A total of 1,641 individuals met the inclusion criteria. Despite the fact that participants were female, we observed a higher rate of resistance to ciprofloxacin in males. The most frequent pathogens identified in urine samples were Escherichia coli, Klebsiella pneumoniae and Staphylococcus saprophyticus. Antimicrobial resistance has been observed mainly for ampicillin, sulfamethoxazole + trimethoprim and ciprofloxacin. Moreover, E. coli has shown the highest rate of ciprofloxacin resistance, reaching 36% of ciprofloxacin resistant strains in 2014. The rate of bacterial resistance to ciprofloxacin observed in the studied population is much higher than expected, prompting the need for rational use of this antibiotic, especially in infections caused by E. coli. Prevention of bacterial resistance can be performed through control measures to limit the spread of resistant microorganisms and a rational use of antimicrobial policy.

  17. CIPROFLOXACIN RESISTANCE PATTERN AMONG BACTERIA ISOLATED FROM PATIENTS WITH COMMUNITY-ACQUIRED URINARY TRACT INFECTION

    PubMed Central

    REIS, Ana Carolina Costa; SANTOS, Susana Regia da Silva; de SOUZA, Siane Campos; SALDANHA, Milena Góes; PITANGA, Thassila Nogueira; OLIVEIRA, Ricardo Riccio

    2016-01-01

    SUMMARY Objective: To identify the main bacterial species associated with community-acquired urinary tract infection (UTI) and to assess the pattern of ciprofloxacin susceptibility among bacteria isolated from urine cultures. Methods: We conducted a retrospective study in all the patients with community-acquired UTI seen in Santa Helena Laboratory, Camaçari, Bahia, Brazil during five years (2010-2014). All individuals who had a positive urine culture result were included in this study. Results: A total of 1,641 individuals met the inclusion criteria. Despite the fact that participants were female, we observed a higher rate of resistance to ciprofloxacin in males. The most frequent pathogens identified in urine samples were Escherichia coli, Klebsiella pneumoniae and Staphylococcus saprophyticus. Antimicrobial resistance has been observed mainly for ampicillin, sulfamethoxazole + trimethoprim and ciprofloxacin. Moreover, E. coli has shown the highest rate of ciprofloxacin resistance, reaching 36% of ciprofloxacin resistant strains in 2014. Conclusion: The rate of bacterial resistance to ciprofloxacin observed in the studied population is much higher than expected, prompting the need for rational use of this antibiotic, especially in infections caused by E. coli. Prevention of bacterial resistance can be performed through control measures to limit the spread of resistant microorganisms and a rational use of antimicrobial policy. PMID:27410913

  18. Antibiotic-resistant genes and antibiotic-resistant bacteria in the effluent of urban residential areas, hospitals, and a municipal wastewater treatment plant system.

    PubMed

    Li, Jianan; Cheng, Weixiao; Xu, Like; Strong, P J; Chen, Hong

    2015-03-01

    In this study, we determined the abundance of 8 antibiotics (3 tetracyclines, 4 sulfonamides, and 1 trimethoprim), 12 antibiotic-resistant genes (10 tet, 2 sul), 4 antibiotic-resistant bacteria (tetracycline, sulfamethoxazole, and combined resistance), and class 1 integron integrase gene (intI1) in the effluent of residential areas, hospitals, and municipal wastewater treatment plant (WWTP) systems. The concentrations of total/individual targets (antibiotics, genes, and bacteria) varied remarkably among different samples, but the hospital samples generally had a lower abundance than the residential area samples. The WWTP demonstrated removal efficiencies of 50.8% tetracyclines, 66.8% sulfonamides, 0.5 logs to 2.5 logs tet genes, and less than 1 log of sul and intI1 genes, as well as 0.5 log to 1 log removal for target bacteria. Except for the total tetracycline concentration and the proportion of tetracycline-resistant bacteria (R (2) = 0.330, P < 0.05), there was no significant correlation between antibiotics and the corresponding resistant bacteria (P > 0.05). In contrast, various relationships were identified between antibiotics and antibiotic resistance genes (P < 0.05). Tet (A) and tet (B) displayed noticeable relationships with both tetracycline and combined antibiotic-resistant bacteria (P < 0.01).

  19. Enumeration and characterization of antimicrobial-resistant Escherichia coli bacteria in effluent from municipal, hospital, and secondary treatment facility sources.

    PubMed

    Galvin, Sandra; Boyle, Fiona; Hickey, Paul; Vellinga, Akke; Morris, Dearbháile; Cormican, Martin

    2010-07-01

    We describe a modification of the most probable number (MPN) method for rapid enumeration of antimicrobial-resistant Escherichia coli bacteria in aqueous environmental samples. E. coli (total and antimicrobial-resistant) bacteria were enumerated in effluent samples from a hospital (n = 17) and municipal sewers upstream (n = 5) and downstream (n = 5) from the hospital, effluent samples from throughout the treatment process (n = 4), and treated effluent samples (n = 13). Effluent downstream from the hospital contained a higher proportion of antimicrobial-resistant E. coli than that upstream from the hospital. Wastewater treatment reduced the numbers of E. coli bacteria (total and antimicrobial resistant); however, antimicrobial-resistant E. coli was not eliminated, and E. coli resistant to cefotaxime (including extended-spectrum beta-lactamase [ESBL] producers), ciprofloxacin, and cefoxitin was present in treated effluent samples.

  20. Diversity and characterization of mercury-resistant bacteria in snow, freshwater and sea-ice brine from the High Arctic.

    PubMed

    Møller, Annette K; Barkay, Tamar; Abu Al-Soud, Waleed; Sørensen, Søren J; Skov, Henrik; Kroer, Niels

    2011-03-01

    It is well-established that atmospheric deposition transports mercury from lower latitudes to the Arctic. The role of bacteria in the dynamics of the deposited mercury, however, is unknown. We characterized mercury-resistant bacteria from High Arctic snow, freshwater and sea-ice brine. Bacterial densities were 9.4 × 10(5), 5 × 10(5) and 0.9-3.1 × 10(3) cells mL(-1) in freshwater, brine and snow, respectively. Highest cultivability was observed in snow (11.9%), followed by freshwater (0.3%) and brine (0.03%). In snow, the mercury-resistant bacteria accounted for up to 31% of the culturable bacteria, but <2% in freshwater and brine. The resistant bacteria belonged to the Alpha-, Beta- and Gammaproteobacteria, Firmicutes, Actinobacteria, and Bacteriodetes. Resistance levels of most isolates were not temperature dependent. Of the resistant isolates, 25% reduced Hg(II) to Hg(0). No relation between resistance level, ability to reduce Hg(II) and phylogenetic group was observed. An estimation of the potential bacterial reduction of Hg(II) in snow suggested that it was important in the deeper snow layers where light attenuation inhibited photoreduction. Thus, by reducing Hg(II) to Hg(0), mercury-resistant bacteria may limit the supply of substrate for methylation processes and, hence, contribute to lowering the risk that methylmercury is being incorporated into the Arctic food chains.

  1. Prevalence of antibiotic resistance in bacteria isolated from drinking well water available in Guinea-Bissau (West Africa).

    PubMed

    Machado, A; Bordalo, A A

    2014-08-01

    The dissemination of antibiotic-resistant bacteria and the spread of antibiotic resistance genes are a major public health concern worldwide, being even proposed as emerging contaminants. The aquatic environment is a recognized reservoir of antibiotic resistant bacteria, and antibiotic resistance genes have been recently detected in drinking water. In this study, the water quality and the prevalence of antibiotic resistance of heterotrophic culturable bacteria were characterized seasonally in wells that serve the population of Guinea-Bissau (West Africa) as the sole source of water for drinking and other domestic proposes. The results revealed that well water was unfit for human consumption independently of the season, owing to high acidity and heavy fecal contamination. Moreover, potentially pathogenic bacteria, which showed resistance to the most prescribed antibiotics in Guinea-Bissau, were isolated from well water, posing an additional health risk. Our results suggest that well water not only fosters the transmission of potential pathogenic bacteria, but also represents an important reservoir for the proliferation of antibiotic resistant bacteria, that can aggravate the potential to cause disease in a very vulnerable population that has no other alternative but to consume such water. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. [Resistance of chemoorganotrophic bacteria isolated from Antarctic cliffs to toxic metals].

    PubMed

    Tashirev, A B; Rokitko, P V; Levishko, A S; Romanovskaia, V A; Tashireva, A A

    2012-01-01

    Resistance to toxic metals ( Hg2+, Cu2+, Ni2+, Co2+, Cr(VI)) of bacteria isolated from rock lichen samples of vertical cliffs located on the biogeographic polygon of Ukrainian Antarctic Station Akademik Vernadsky (island Galindez) is studied. Among the Antarctic rock microorganisms isolated on nonselective medium (without toxic metals), bacteria able to grow at toxic metal concentrations lethal for the majority of microorganisms (Hg2+, Cu2+, Ni2+, Co2+, Cr(VI)) are found out. The studied bacteria are most resistant to Cr(VI) possessing oxidative properties in concentration range 1.25-20.0 g/l depending on the strain. Maximal metal concentrations, at which the growth of bacteria was possible, was: Ni2+ to toxic metals - 2.0 g/l, Co(2+) - 0.1 g/l. In the presence of metal ions possessing both replacing and oxidative properties the strains grew in a concentration range: Hg(2+) - 0.005-0.05 g/l, Cu(2+) - 0.1-1.25 g/l. The highest toxic effect was shown for mercury ions. One of the isolated Antarctic strains which was superresistant to high toxic metal concentrations (g/l): Cr(VI) - 20.0, Ni(2+) - 2.0, Cu(2+) - 1.25, Co(2+) - 0.1, Hg(2+) - 0.05. Thus, for the Antarctic bacteria isolated from rock damaging or bactericidal toxic metal concentrations are by 2-3 orders higher than for the majority of microorganisms.

  3. Characterization of antibiotic resistance in commensal bacteria from an aquaculture ecosystem

    PubMed Central

    Huang, Ying; Zhang, Lu; Tiu, Laura; Wang, Hua H.

    2015-01-01

    The objective of the study was to improve the understanding of antibiotic resistance (AR) ecology through characterization of antibiotic-resistant commensal isolates associated with an aquaculture production system. A total of 4767 isolates non-susceptible to sulfamethoxazole/trimethoprim (Sul/Tri), tetracycline (Tet), erythromycin (Erm), or cefotaxime (Ctx), originated from fish, feed, and environmental samples of an aquaculture farm with no known history of antibiotic appli