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Sample records for multimetal resistant bacterial

  1. Comparison of two multimetal resistant bacterial strains: Enterobacter sp. YSU and Stenotrophomonas maltophilia ORO2.

    PubMed

    Holmes, Andrew; Vinayak, Anubhav; Benton, Cherise; Esbenshade, Aaron; Heinselman, Carlisle; Frankland, Daniel; Kulkarni, Samatha; Kurtanich, Adrienne; Caguiat, Jonathan

    2009-11-01

    The Y-12 plant in Oak Ridge, TN, which manufactured nuclear weapons during World War II and the Cold War, contaminated East Fork Poplar Creek with heavy metals. The multimetal resistant bacterial strain, Stenotrophomonas maltophilia Oak Ridge strain O2 (S. maltophilia O2), was isolated from East Fork Poplar Creek. Sequence analysis of 16s rDNA suggested that our working strain of S. maltophilia O2 was a strain of Enterobacter. Phylogenetic tree analysis and biochemical tests confirmed that it belonged to an Enterobacter species. This new strain was named Enterobacter sp. YSU. Using a modified R3A growth medium, R3A-Tris, the Hg(II), Cd(II), Zn(II), Cu(II), Au(III), Cr(VI), Ag(I), As(III), and Se(IV) MICs for a confirmed strain of S. maltophilia O2 were 0.24, 0.33, 5, 5, 0.25, 7, 0.03, 14, and 40 mM, respectively, compared to 0.07, 0.24, 0.8, 3, 0.05, 0.4, 0.08, 14, and 40 mM, respectively, for Enterobacter sp. YSU. Although S. maltophilia O2 was generally more metal resistant than Enterobacter sp. YSU, in comparison to Escherichia coli strain HB101, Enterobacter sp. YSU was resistant to Hg(II), Cd(II), Zn(II), Au(III), Ag(I), As(III), and Se(IV). By studying metal resistances in these two strains, it may be possible to understand what makes one microorganism more metal resistant than another microorganism. This work also provided benchmark MICs that can be used to evaluate the metal resistance properties of other bacterial isolates from East Fork Poplar Creek and other metal contaminated sites.

  2. The hyperaccumulator Sedum plumbizincicola harbors metal-resistant endophytic bacteria that improve its phytoextraction capacity in multi-metal contaminated soil.

    PubMed

    Ma, Ying; Oliveira, Rui S; Nai, Fengjiao; Rajkumar, Mani; Luo, Yongming; Rocha, Inês; Freitas, Helena

    2015-06-01

    Endophyte-assisted phytoremediation has recently been suggested as a successful approach for ecological restoration of metal contaminated soils, however little information is available on the influence of endophytic bacteria on the phytoextraction capacity of metal hyperaccumulating plants in multi-metal polluted soils. The aims of our study were to isolate and characterize metal-resistant and 1-aminocyclopropane-1-carboxylate (ACC) utilizing endophytic bacteria from tissues of the newly discovered Zn/Cd hyperaccumulator Sedum plumbizincicola and to examine if these endophytic bacterial strains could improve the efficiency of phytoextraction of multi-metal contaminated soils. Among a collection of 42 metal resistant bacterial strains isolated from the tissues of S. plumbizincicola grown on Pb/Zn mine tailings, five plant growth promoting endophytic bacterial strains (PGPE) were selected due to their ability to promote plant growth and to utilize ACC as the sole nitrogen source. The five isolates were identified as Bacillus pumilus E2S2, Bacillus sp. E1S2, Bacillus sp. E4S1, Achromobacter sp. E4L5 and Stenotrophomonas sp. E1L and subsequent testing revealed that they all exhibited traits associated with plant growth promotion, such as production of indole-3-acetic acid and siderophores and solubilization of phosphorus. These five strains showed high resistance to heavy metals (Cd, Zn and Pb) and various antibiotics. Further, inoculation of these ACC utilizing strains significantly increased the concentrations of water extractable Cd and Zn in soil. Moreover, a pot experiment was conducted to elucidate the effects of inoculating metal-resistant ACC utilizing strains on the growth of S. plumbizincicola and its uptake of Cd, Zn and Pb in multi-metal contaminated soils. Out of the five strains, B. pumilus E2S2 significantly increased root (146%) and shoot (17%) length, fresh (37%) and dry biomass (32%) of S. plumbizincicola as well as plant Cd uptake (43%), whereas

  3. Using a Multimeter to Study an RC Circuit.

    ERIC Educational Resources Information Center

    King, John G.; French, A. P.

    1995-01-01

    Presents several resistance measurement experiments based on the function of a magnetic multimeter. Resistance is measured in terms of the current that the internal dry cell drives through the unknown resistor connected across the input terminals. For use with digital and nondigital multimeters. (LZ)

  4. Bacterial cheating limits antibiotic resistance

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    The widespread use of antibiotics has led to the evolution of resistance in bacteria. Bacteria can gain resistance to the antibiotic ampicillin by acquiring a plasmid carrying the gene beta-lactamase, which inactivates the antibiotic. This inactivation may represent a cooperative behavior, as the entire bacterial population benefits from removing the antibiotic. The cooperative nature of this growth suggests that a cheater strain---which does not contribute to breaking down the antibiotic---may be able to take advantage of cells cooperatively inactivating the antibiotic. Here we find experimentally that a ``sensitive'' bacterial strain lacking the plasmid conferring resistance can invade a population of resistant bacteria, even in antibiotic concentrations that should kill the sensitive strain. We observe stable coexistence between the two strains and find that a simple model successfully explains the behavior as a function of antibiotic concentration and cell density. We anticipate that our results will provide insight into the evolutionary origin of phenotypic diversity and cooperative behaviors.

  5. Bacterial strategies of resistance to antimicrobial peptides.

    PubMed

    Joo, Hwang-Soo; Fu, Chih-Iung; Otto, Michael

    2016-05-26

    Antimicrobial peptides (AMPs) are a key component of the host's innate immune system, targeting invasive and colonizing bacteria. For successful survival and colonization of the host, bacteria have a series of mechanisms to interfere with AMP activity, and AMP resistance is intimately connected with the virulence potential of bacterial pathogens. In particular, because AMPs are considered as potential novel antimicrobial drugs, it is vital to understand bacterial AMP resistance mechanisms. This review gives a comparative overview of Gram-positive and Gram-negative bacterial strategies of resistance to various AMPs, such as repulsion or sequestration by bacterial surface structures, alteration of membrane charge or fluidity, degradation and removal by efflux pumps.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'.

  6. Boosting bacterial metabolism to combat antibiotic resistance.

    PubMed

    Bhargava, Prerna; Collins, James J

    2015-02-03

    The metabolic state of a bacterial cell influences its susceptibility to antibiotics. In this issue, Peng et al. (2015) show that resistant bacteria can be sensitized to antibiotic treatment through the addition of exogenous metabolites that stimulate central metabolic pathways and increase drug uptake.

  7. Effects of Cd, Pb, Zn, Cu-resistant endophytic Enterobacter sr CBSB1 and Rhodotorula sp. CBSB79 on the growth and phytoextraction of Brassica plants in multimetal contaminated soils.

    PubMed

    Wang, Wenfeng; Deng, Zujun; Tan, Hongming; Cao, Lixiang

    2013-01-01

    To survey the effects of endophytic Enterobacter sp. CBSB1 and Rhodotorula sp. CBSB79 resistant to Cd2+, Pb2+, Zn2+, and Cu2+ on the growth and phytoextraction of Brassica, the endophytes were isolated by surface- sterilized methods and characterized. The CBSB1 significantly increased 44.2% of the dry weight of Brassica napus in the multimetal contaminated soil (P < 0.05) and showed no effect or declined the dry weight of B. alboglabra, B. campestris ssp. chinensis var. cummunis, B. campestris ssp. chinensis var. utilis cv. Youqing12, B. campestris ssp. chinensis var. utilis cv. Lvbao701 plants. The dry weights of B. napus, B. campestris ssp. chinensis var. utilis, and B. alboglabra showed a significant increase when the CBSB79 was inoculated (P < 0.05). In general, inoculation with bacteria and yeast did not greatly alter the metal concentration in plant tissues. Compared to Enterobacter sp. CBSB1, the yeast Rhodotorula sp CBSB79 showed higher potentials to improve extraction efficacy of Cd, Pb, Zn, and Cu by Brassica seedlings in the field.

  8. Colourful parrot feathers resist bacterial degradation.

    PubMed

    Burtt, Edward H; Schroeder, Max R; Smith, Lauren A; Sroka, Jenna E; McGraw, Kevin J

    2011-04-23

    The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage.

  9. Colourful parrot feathers resist bacterial degradation

    PubMed Central

    Burtt, Edward H.; Schroeder, Max R.; Smith, Lauren A.; Sroka, Jenna E.; McGraw, Kevin J.

    2011-01-01

    The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage. PMID:20926430

  10. Persistence of antibiotic resistance in bacterial populations.

    PubMed

    Andersson, Dan I; Hughes, Diarmaid

    2011-09-01

    Unfortunately for mankind, it is very likely that the antibiotic resistance problem we have generated during the last 60 years due to the extensive use and misuse of antibiotics is here to stay for the foreseeable future. This view is based on theoretical arguments, mathematical modeling, experiments and clinical interventions, suggesting that even if we could reduce antibiotic use, resistant clones would remain persistent and only slowly (if at all) be outcompeted by their susceptible relatives. In this review, we discuss the multitude of mechanisms and processes that are involved in causing the persistence of chromosomal and plasmid-borne resistance determinants and how we might use them to our advantage to increase the likelihood of reversing the problem. Of particular interest is the recent demonstration that a very low antibiotic concentration can be enriching for resistant bacteria and the implication that antibiotic release into the environment could contribute to the selection for resistance. Several mechanisms are contributing to the stability of antibiotic resistance in bacterial populations and even if antibiotic use is reduced it is likely that most resistance mechanisms will persist for considerable times.

  11. Bacterial Enzymes and Antibiotic Resistance- Oral Presentation

    SciTech Connect

    Maltz, Lauren

    2015-08-25

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

  12. Impact of repeated single-metal and multi-metal pollution events on soil quality.

    PubMed

    Burges, Aritz; Epelde, Lur; Garbisu, Carlos

    2015-02-01

    Most frequently, soil metal pollution results from the occurrence of repeated single-metal and, above all, multi-metal pollution events, with concomitant adverse consequences for soil quality. Therefore, in this study, we evaluated the impact of repeated single-metal and multi-metal (Cd, Pb, Cu, Zn) pollution events on soil quality, as reflected by the values of a variety of soil microbial parameters with potential as bioindicators of soil functioning. Specifically, parameters of microbial activity (potentially mineralizable nitrogen, β-glucosidase and acid phosphatase activity) and biomass (fungal and bacterial gene abundance by RT-qPCR) were determined, in the artificially metal-polluted soil samples, at regular intervals over a period of 26 weeks. Similarly, we studied the evolution over time of CaCl2-extractable metal fractions, in order to estimate metal bioavailability in soil. Different metals showed different values of bioavailability and relative bioavailability ([metal]bio/[metal]tot) in soil throughout the experiment, under both repeated single-metal and multi-metal pollution events. Both repeated Zn-pollution and multi-metal pollution events led to a significant reduction in the values of acid phosphatase activity, and bacterial and fungal gene abundance, reflecting the negative impact of these repeated events on soil microbial activity and biomass, and, hence, soil quality.

  13. Developing live bacterial vaccines by selecting resistance to antibacterials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four chemicals were used in this study to modify bacterial isolates through chemical-resistance strategy. All bacteria were able to develop high resistance to gossypol. However, none of the gossypol-resistant isolate was attenuated. Although majority of the proflavine hemisulfate-resistant isolates ...

  14. Bacterial and archaeal resistance to ionizing radiation

    NASA Astrophysics Data System (ADS)

    Confalonieri, F.; Sommer, S.

    2011-01-01

    Organisms living in extreme environments must cope with large fluctuations of temperature, high levels of radiation and/or desiccation, conditions that can induce DNA damage ranging from base modifications to DNA double-strand breaks. The bacterium Deinococcus radiodurans is known for its resistance to extremely high doses of ionizing radiation and for its ability to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Recently, extreme ionizing radiation resistance was also generated by directed evolution of an apparently radiation-sensitive bacterial species, Escherichia coli. Radioresistant organisms are not only found among the Eubacteria but also among the Archaea that represent the third kingdom of life. They present a set of particular features that differentiate them from the Eubacteria and eukaryotes. Moreover, Archaea are often isolated from extreme environments where they live under severe conditions of temperature, pressure, pH, salts or toxic compounds that are lethal for the large majority of living organisms. Thus, Archaea offer the opportunity to understand how cells are able to cope with such harsh conditions. Among them, the halophilic archaeon Halobacterium sp and several Pyrococcus or Thermococcus species, such as Thermococcus gammatolerans, were also shown to display high level of radiation resistance. The dispersion, in the phylogenetic tree, of radioresistant prokaryotes suggests that they have independently acquired radioresistance. Different strategies were selected during evolution including several mechanisms of radiation byproduct detoxification and subtle cellular metabolism modifications to help cells recover from radiation-induced injuries, protection of proteins against oxidation, an efficient DNA repair tool box, an original pathway of DNA double-strand break repair, a condensed nucleoid that may prevent the dispersion of the DNA fragments and specific radiation-induced proteins involved in

  15. Bacterial mercury resistance from atoms to ecosystems.

    PubMed

    Barkay, Tamar; Miller, Susan M; Summers, Anne O

    2003-06-01

    Bacterial resistance to inorganic and organic mercury compounds (HgR) is one of the most widely observed phenotypes in eubacteria. Loci conferring HgR in Gram-positive or Gram-negative bacteria typically have at minimum a mercuric reductase enzyme (MerA) that reduces reactive ionic Hg(II) to volatile, relatively inert, monoatomic Hg(0) vapor and a membrane-bound protein (MerT) for uptake of Hg(II) arranged in an operon under control of MerR, a novel metal-responsive regulator. Many HgR loci encode an additional enzyme, MerB, that degrades organomercurials by protonolysis, and one or more additional proteins apparently involved in transport. Genes conferring HgR occur on chromosomes, plasmids, and transposons and their operon arrangements can be quite diverse, frequently involving duplications of the above noted structural genes, several of which are modular themselves. How this very mobile and plastic suite of proteins protects host cells from this pervasive toxic metal, what roles it has in the biogeochemical cycling of Hg, and how it has been employed in ameliorating environmental contamination are the subjects of this review.

  16. Targeting bacterial topoisomerases: how to counter mechanisms of resistance.

    PubMed

    Tse-Dinh, Yuk-Ching

    2016-06-01

    DNA gyrase and topoisomerase IV are type IIA bacterial topoisomerases that are targeted by highly effective antibiotics. However, resistance via multiple mechanisms arises to limit the efficacies of these drugs. Continued research on type IIA bacterial topoisomerases has provided novel approaches to counter the most common resistance mechanism for utilization of these proven targets in antibacterial therapy. Bacterial topoisomerase I is being explored as an alternative target that is not expected to show cross-resistance. Dual targeting or combination therapy could be strategies for circumventing the development of resistance to topoisomerase-targeting antibiotics. Bacterial topoisomerases are high-value bactericidal targets that could continue to be exploited for antibacterial therapy, if new tactics to counter resistance can be adopted.

  17. [Bacterial proteases and bacterial resistance against human innate immunity factors].

    PubMed

    Tiurin, Iu A; Mustafin, I G; Fassakhov, R S

    2011-01-01

    The molecular and cell-mediated mechanisms that are developed by certain opportunistic and pathogenic bacteria and were obtained over the course of evolution to preserve resistance against principal components of human body innate immunity are summarized.

  18. SCREENING OF TRANSGENIC ANTHURIUMS FOR BACTERIAL BLIGHT AND NEMATODE RESISTANCE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anthuriums exhibit limited resistance to bacterial blight caused by Xanthomonas axonopodis pv. dieffenbachiae and to the nematodes Radopholus simile and Meloidogyne javanica. Agrobacterium tumefaciens transformation of embryogenic calli with strains LBA4404, EHA105, and AGLO resulted in transgenic p...

  19. Bacterial Cheating Limits the Evolution of Antibiotic Resistance

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  20. Selection of bacterial wilt-resistant tomato through tissue culture.

    PubMed

    Toyoda, H; Shimizu, K; Chatani, K; Kita, N; Matsuda, Y; Ouchi, S

    1989-06-01

    Bacterial wilt-resistant plants were obtained using a tomato tissue culture system. A virulent strain ofPseudomonas solanacearum secreted some toxic substances into the culture medium. Leaf explant-derived callus tissues which were resistant to these toxic substances in the culture filtrate were selectedin vitro and regenerated into plants. These plants expressed bacterial wilt resistance at the early infection stage to suppress or delay the growth of the inoculated bacteria. On the other hand, complete resistance was obtained in self-pollinated progeny of regenerants derived from non-selected callus tissues. These plants showed a high resistance when inoculated with this strain, and were also resistant when planted in a field infested with a different strain of the pathogen.

  1. Assessment of Bacterial Antibiotic Resistance Transfer in the Gut

    PubMed Central

    Schjørring, Susanne; Krogfelt, Karen A.

    2011-01-01

    We assessed horizontal gene transfer between bacteria in the gastrointestinal (GI) tract. During the last decades, the emergence of antibiotic resistant strains and treatment failures of bacterial infections have increased the public awareness of antibiotic usage. The use of broad spectrum antibiotics creates a selective pressure on the bacterial flora, thus increasing the emergence of multiresistant bacteria, which results in a vicious circle of treatments and emergence of new antibiotic resistant bacteria. The human gastrointestinal tract is a massive reservoir of bacteria with a potential for both receiving and transferring antibiotic resistance genes. The increased use of fermented food products and probiotics, as food supplements and health promoting products containing massive amounts of bacteria acting as either donors and/or recipients of antibiotic resistance genes in the human GI tract, also contributes to the emergence of antibiotic resistant strains. This paper deals with the assessment of antibiotic resistance gene transfer occurring in the gut. PMID:21318188

  2. Antibiotic resistant bacterial profiles of anaerobic swine lagoon effluent.

    PubMed

    Brooks, J P; McLaughlin, M R

    2009-01-01

    Although land application of swine (Sus scrofa) manure lagoon effluent is a common and effective method of disposal, the presence of antibiotic-resistant bacteria, both pathogenic and commensal can complicate already understood issues associated with its safe disposal. The aim of this study was to assess antibiotic resistance in swine lagoon bacteria from sow, nursery, and finisher farms in the southeastern United States. Effluents from 37 lagoons were assayed for the presence of Escherichia coli, Campylobacter, Listeria, and Salmonella. Antibiotic resistance profiles were determined by the Kirby-Bauer swab method for 12 antibiotics comprising eight classes. Statistical analyses indicated that farm type influenced the amount and type of resistance, with nurseries and sow farms ranking as most influential, perhaps due to use of more antibiotic treatments. Finisher farms tended to have the least amount of antibiotic class resistance, signaling an overall healthier market pig, and less therapeutic or prophylactic antibiotic use. Many bacterial isolates were resistant to penicillin, cephalosporin, and tetracycline class antibiotics, while nearly all were susceptible to quinolone antibiotics. It appeared that swine farm type had a significant association with the amount of resistance associated with bacterial genera sampled from the lagoons; nurseries contributed the largest amount of bacterial resistance.

  3. Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants

    PubMed Central

    Blanco, Paula; Hernando-Amado, Sara; Reales-Calderon, Jose Antonio; Corona, Fernando; Lira, Felipe; Alcalde-Rico, Manuel; Bernardini, Alejandra; Sanchez, Maria Blanca; Martinez, Jose Luis

    2016-01-01

    Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics. PMID:27681908

  4. Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants.

    PubMed

    Blanco, Paula; Hernando-Amado, Sara; Reales-Calderon, Jose Antonio; Corona, Fernando; Lira, Felipe; Alcalde-Rico, Manuel; Bernardini, Alejandra; Sanchez, Maria Blanca; Martinez, Jose Luis

    2016-02-16

    Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics.

  5. Proteome studies of bacterial antibiotic resistance mechanisms.

    PubMed

    Vranakis, Iosif; Goniotakis, Ioannis; Psaroulaki, Anna; Sandalakis, Vassilios; Tselentis, Yannis; Gevaert, Kris; Tsiotis, Georgios

    2014-01-31

    Ever since antibiotics were used to help humanity battle infectious diseases, microorganisms straight away fought back. Antibiotic resistance mechanisms indeed provide microbes with possibilities to by-pass and survive the action of antibiotic drugs. Several methods have been employed to identify these microbial resistance mechanisms in an ongoing effort to reduce the steadily increasing number of treatment failures due to multi-drug-resistant microbes. Proteomics has evolved to an important tool for this area of research. Following rapid advances in whole genome sequencing, proteomic technologies have been widely used to investigate microbial gene expression. This review highlights the contribution of proteomics in identifying microbial drug resistance mechanisms. It summarizes different proteomic studies on bacteria resistant to different antibiotic drugs. The review further includes an overview of the methodologies used, as well as lists key proteins identified, thus providing the reader not only a summary of research already done, but also directions for future research. This article is part of a Special Issue entitled: Trends in Microbial Proteomics.

  6. Bacterial resistance to antibodies: a model evolutionary study.

    PubMed

    Schulman, Lawrence S

    2017-03-21

    The tangled nature model of evolution (reviewed in the main text) is adapted for use in the study of antibody resistance acquired by horizontal gene transfer. Exchanges of DNA and the acquisition of resistant gene sequences are considered. For the parameters used, resistant strains rapidly proliferate and dominate, although initial intense antibiotic treatment can occasionally prevent this. Variation in genome distribution appears to be long tailed. If this is reflected in nature, the occurrence of resistant bacterial strains can be expected, as well as considerable variation in patient outcomes.

  7. Mechanisms and consequences of bacterial resistance to antimicrobial peptides.

    PubMed

    Andersson, D I; Hughes, D; Kubicek-Sutherland, J Z

    2016-05-01

    Cationic antimicrobial peptides (AMPs) are an intrinsic part of the human innate immune system. Over 100 different human AMPs are known to exhibit broad-spectrum antibacterial activity. Because of the increased frequency of resistance to conventional antibiotics there is an interest in developing AMPs as an alternative antibacterial therapy. Several cationic peptides that are derivatives of AMPs from the human innate immune system are currently in clinical development. There are also ongoing clinical studies aimed at modulating the expression of AMPs to boost the human innate immune response. In this review we discuss the potential problems associated with these therapeutic approaches. There is considerable experimental data describing mechanisms by which bacteria can develop resistance to AMPs. As for any type of drug resistance, the rate by which AMP resistance would emerge and spread in a population of bacteria in a natural setting will be determined by a complex interplay of several different factors, including the mutation supply rate, the fitness of the resistant mutant at different AMP concentrations, and the strength of the selective pressure. Several studies have already shown that AMP-resistant bacterial mutants display broad cross-resistance to a variety of AMPs with different structures and modes of action. Therefore, routine clinical administration of AMPs to treat bacterial infections may select for resistant bacterial pathogens capable of better evading the innate immune system. The ramifications of therapeutic levels of exposure on the development of AMP resistance and bacterial pathogenesis are not yet understood. This is something that needs to be carefully studied and monitored if AMPs are used in clinical settings.

  8. Evolution of antibiotic resistance by human and bacterial niche construction.

    PubMed

    Boni, Maciej F; Feldman, Marcus W

    2005-03-01

    Antibiotic treatment by humans generates strong viability selection for antibiotic-resistant bacterial strains. The frequency of host antibiotic use often determines the strength of this selection, and changing patterns of antibiotic use can generate many types of behaviors in the population dynamics of resistant and sensitive bacterial populations. In this paper, we present a simple model of hosts dimorphic for their tendency to use/avoid antibiotics and bacterial pathogens dimorphic in their resistance/sensitivity to antibiotic treatment. When a constant fraction of hosts uses antibiotics, the two bacterial strain populations can coexist unless host use-frequency is above a critical value; this critical value is derived as the ratio of the fitness cost of resistance to the fitness cost of undergoing treatment. When strain frequencies can affect host behavior, the dynamics may be analyzed in the light of niche construction. We consider three models underlying changing host behavior: conformism, the avoidance of long infections, and adherence to the advice of public health officials. In the latter two, we find that the pathogen can have quite a strong effect on host behavior. In particular, if antibiotic use is discouraged when resistance levels are high, we observe a classic niche-construction phenomenon of maintaining strain polymorphism even in parameter regions where it would not be expected.

  9. Mechanisms of bacterial resistance to macrolide antibiotics.

    PubMed

    Nakajima, Yoshinori

    1999-06-01

    Macrolides have been used in the treatment of infectious diseases since the late 1950s. Since that time, a finding of antagonistic action between erythromycin and spiramycin in clinical isolates1 led to evidence of the biochemical mechanism and to the current understanding of inducible or constitutive resistance to macrolides mediated by erm genes containing, respectively, the functional regulation mechanism or constitutively mutated regulatory region. These resistant mechanisms to macrolides are recognized in clinically isolated bacteria. (1) A methylase encoded by the erm gene can transform an adenine residue at 2058 (Escherichia coli equivalent) position of 23S rRNA into an 6N, 6N-dimethyladenine. Position 2058 is known to reside either in peptidyltransferase or in the vicinity of the enzyme region of domain V. Dimethylation renders the ribosome resistant to macrolides (MLS). Moreover, another finding adduced as evidence is that a mutation in the domain plays an important role in MLS resistance: one of several mutations (transition and transversion) such as A2058G, A2058C or U, and A2059G, is usually associated with MLS resistance in a few genera of bacteria. (2) M (macrolide antibiotics)- and MS (macrolide and streptogramin type B antibiotics)- or PMS (partial macrolide and streptogramin type B antibiotics)-phenotype resistant bacteria cause decreased accumulation of macrolides, occasionally including streptogramin type B antibiotics. The decreased accumulation, probably via enhanced efflux, is usually inferred from two findings: (i) the extent of the accumulated drug in a resistant cell increases as much as that in a susceptible cell in the presence of an uncoupling agent such as carbonylcyanide-m-chlorophenylhydrazone (CCCP), 2,4-dinitrophenol (DNP), and arsenate; (ii) transporter proteins, in M-type resistants, have mutual similarity to the 12-transmembrane domain present in efflux protein driven by proton-motive force, and in MS- or PMS-type resistants

  10. Alternatives to overcoming bacterial resistances: State-of-the-art.

    PubMed

    Rios, Alessandra C; Moutinho, Carla G; Pinto, Flávio C; Del Fiol, Fernando S; Jozala, Angela; Chaud, Marco V; Vila, Marta M D C; Teixeira, José A; Balcão, Victor M

    2016-10-01

    Worldwide, bacterial resistance to chemical antibiotics has reached such a high level that endangers public health. Presently, the adoption of alternative strategies that promote the elimination of resistant microbial strains from the environment is of utmost importance. This review discusses and analyses several (potential) alternative strategies to current chemical antibiotics. Bacteriophage (or phage) therapy, although not new, makes use of strictly lytic phage particles as an alternative, or a complement, in the antimicrobial treatment of bacterial infections. It is being rediscovered as a safe method, because these biological entities devoid of any metabolic machinery do not possess any affinity whatsoever to eukaryotic cells. Lysin therapy is also recognized as an innovative antimicrobial therapeutic option, since the topical administration of preparations containing purified recombinant lysins with amounts in the order of nanograms, in infections caused by Gram-positive bacteria, demonstrated a high therapeutic potential by causing immediate lysis of the target bacterial cells. Additionally, this therapy exhibits the potential to act synergistically when combined with certain chemical antibiotics already available on the market. Another potential alternative antimicrobial therapy is based on the use of antimicrobial peptides (AMPs), amphiphilic polypeptides that cause disruption of the bacterial membrane and can be used in the treatment of bacterial, fungal and viral infections, in the prevention of biofilm formation, and as antitumoral agents. Interestingly, bacteriocins are a common strategy of bacterial defense against other bacterial agents, eliminating the potential opponents of the former and increasing the number of available nutrients in the environment for their own growth. They can be applied in the food industry as biopreservatives and as probiotics, and also in fighting multi-resistant bacterial strains. The use of antibacterial antibodies

  11. Antibiotics and Bacterial Resistance in the 21st Century

    PubMed Central

    Fair, Richard J; Tor, Yitzhak

    2014-01-01

    Dangerous, antibiotic resistant bacteria have been observed with increasing frequency over the past several decades. In this review the factors that have been linked to this phenomenon are addressed. Profiles of bacterial species that are deemed to be particularly concerning at the present time are illustrated. Factors including economic impact, intrinsic and acquired drug resistance, morbidity and mortality rates, and means of infection are taken into account. Synchronously with the waxing of bacterial resistance there has been waning antibiotic development. The approaches that scientists are employing in the pursuit of new antibacterial agents are briefly described. The standings of established antibiotic classes as well as potentially emerging classes are assessed with an emphasis on molecules that have been clinically approved or are in advanced stages of development. Historical perspectives, mechanisms of action and resistance, spectrum of activity, and preeminent members of each class are discussed. PMID:25232278

  12. Antiplaque biocides and bacterial resistance: a review.

    PubMed

    Sreenivasan, Prem; Gaffar, Abdul

    2002-11-01

    Modern dentistry emphasizes the importance of dental plaque control to improve oral health. The use of oral care formulations with antiplaque biocides plays a crucial role in patient-directed approaches for plaque control. The antiplaque efficacies of these formulations have been extensively studied in many long-term clinical studies designed in accordance with well-accepted guidelines. The results from these studies conclusively demonstrate that long-term use of oral care formulations with well-known antiplaque biocides such as chlorhexidine and triclosan reduce supragingival plaque and gingivitis. This review summarizes microbiological results from clinical studies conducted with oral care formulations containing antiplaque biocides. Results from a number of long-term clinical studies conducted under real-life use conditions indicate no adverse alterations in the bacteria found in dental plaque or emergent microbial resistance. Additionally, microbial sampling of dental plaque subsequent to extended use of antiplaque biocides reveals no increase in resistant microflora. Large numbers of common oral bacteria isolated from patients using chlorhexidine indicate no increase in microbial resistance to chlorhexidine or to commonly used antibiotics. The effects of antiplaque biocides containing oral care formulations on dental plaque that exists naturally as a biofilm are examined. These formulations contain biocide, surfactants, polymers and other components that are effective against the biofilm. In summary, the results of studies on the real-life use of oral care formulations with antiplaque biocides show no emergence of resistant microflora or alterations of the oral microbiota, while such formulations have been found to provide the benefits of reducing plaque and gingivitis.

  13. Management of multidrug resistant bacterial endemic.

    PubMed

    Zahar, J-R; Lesprit, P

    2014-09-01

    The fight against multi-drug resistant Gram-negative bacilli (MDRGNB), especially extended-spectrum β-lactamase producing Enterobacteriaceae, is about to be lost in our country. The emergence of new resistance mechanisms to carbapenems in these Enterobacteriaceae exposes patients to a risk of treatment failure without any other therapeutic options. This dramatic situation is paradoxical because we are well aware of the 2 major factors responsible for this situation: 1) MDRO cross-transmission, associated with a low compliance to standard precautions, especially hand hygiene, and 2) overexposure of patients to antibiotics. The implementation of a "search and isolate" policy, which was justified to control the spread of some MDRO that remained rare in the country, was not associated with a better adherence to standard precautions. The antibiotic policy and the measures implemented to control antibiotic consumptions have rarely been enforced and have shown inconsistent results. Notably, no significant decrease of antibiotic consumption has been observed. There is no excuse for these poor results, because some authors evaluating the effectiveness of programs for the control of MDRO have reported their positive effects on antimicrobial resistance without any detrimental effects. It is now urgent to deal with the 2 major factors by establishing an educational and persuasive program with quantified and opposable objectives. Firstly, we have to improve the observance of hand hygiene above 70%. Secondly, we have to define and reach a target for the reduction of antibiotic consumption both in community and in hospital settings.

  14. Detection of bacterial blight resistance genes in basmati rice landraces.

    PubMed

    Ullah, I; Jamil, S; Iqbal, M Z; Shaheen, H L; Hasni, S M; Jabeen, S; Mehmood, A; Akhter, M

    2012-07-20

    Aromatic basmati rice is vulnerable to bacterial blight disease. Genes conferring resistance to bacterial blight have been identified in coarse rice; however, their incorporation into basmati varieties compromises the prized basmati aroma. We identified bacterial blight resistance genes Xa4, xa5, Xa7, and xa13 in 52 basmati landraces and five basmati cultivars using PCR markers. The Xa7 gene was found to be the most prevalent among the cultivars and landraces. The cultivars Basmati-385 and Basmati-2000 also contained the Xa4 gene; however, xa5 and xa13 were confined to landraces only. Ten landraces were found to have multiple resistance genes. Landraces Basmati-106, Basmati-189 and Basmati-208 contained Xa4 and Xa7 genes. Whereas, landraces Basmati-122, Basmati-427, Basmati-433 were observed to have xa5 and Xa7 genes. Landraces Basmati-48, Basmati-51A, Basmati-334, and Basmati-370A possessed Xa7 and xa13 genes. The use of landraces containing recessive genes xa5 and xa13 as donor parents in hybridization with cultivars Basmati-385 and Basmati-2000, which contain the genes Xa4 and Xa7, will expedite efforts to develop bacterial blight-resistant basmati rice cultivars through marker assisted selection, based on a pyramiding approach, without compromising aroma and grain quality.

  15. Genetics and breeding of bacterial leaf spot resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf spot (BLS) caused by the pathogen Xanthomonas campestris pv. vitians (Xcv) is a globally important disease of whole head and baby leaf lettuce that reduces crop yield and quality. Host resistance is the most feasible method to reduce disease losses. Screening Lactuca accessions has id...

  16. Test for bacterial resistance build-up against plasma treatment

    NASA Astrophysics Data System (ADS)

    Zimmermann, J. L.; Shimizu, T.; Schmidt, H.-U.; Li, Y.-F.; Morfill, G. E.; Isbary, G.

    2012-07-01

    It is well known that the evolution of resistance of microorganisms to a range of different antibiotics presents a major problem in the control of infectious diseases. Accordingly, new bactericidal ‘agents’ are in great demand. Using a cold atmospheric pressure (CAP) plasma dispenser operated with ambient air, a more than five orders of magnitude inactivation or reduction of Methicillin-resistant Staphylococcus aureus (MRSA; resistant against a large number of the tested antibiotics) was obtained in less than 10 s. This makes CAP the most promising candidate for combating nosocomial (hospital-induced) infections. To test for the occurrence and development of bacterial resistance against such plasmas, experiments with Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Enterococcus mundtii) were performed. The aim was to determine quantitative limits for primary (naturally) or secondary (acquired) resistance against the plasma treatment. Our results show that E. coli and E. mundtii possess no primary resistance against the plasma treatment. By generating four generations of bacteria for every strain, where the survivors of the plasma treatment were used for the production of the next generation, a lower limit to secondary resistance was obtained. Our results indicate that CAP technology could contribute to the control of infections in hospitals, in outpatient care and in disaster situations, providing a new, fast and efficient broad-band disinfection technology that is not constrained by bacterial resistance mechanisms.

  17. Persistence and resistance as complementary bacterial adaptations to antibiotics.

    PubMed

    Vogwill, T; Comfort, A C; Furió, V; MacLean, R C

    2016-06-01

    Bacterial persistence represents a simple of phenotypic heterogeneity, whereby a proportion of cells in an isogenic bacterial population can survive exposure to lethal stresses such as antibiotics. In contrast, genetically based antibiotic resistance allows for continued growth in the presence of antibiotics. It is unclear, however, whether resistance and persistence are complementary or alternative evolutionary adaptations to antibiotics. Here, we investigate the co-evolution of resistance and persistence across the genus Pseudomonas using comparative methods that correct for phylogenetic nonindependence. We find that strains of Pseudomonas vary extensively in both their intrinsic resistance to antibiotics (ciprofloxacin and rifampicin) and persistence following exposure to these antibiotics. Crucially, we find that persistence correlates positively to antibiotic resistance across strains. However, we find that different genes control resistance and persistence implying that they are independent traits. Specifically, we find that the number of type II toxin-antitoxin systems (TAs) in the genome of a strain is correlated to persistence, but not resistance. Our study shows that persistence and antibiotic resistance are complementary, but independent, evolutionary adaptations to stress and it highlights the key role played by TAs in the evolution of persistence.

  18. Cooperative Bacterial Growth Dynamics Predict the Evolution of Antibiotic Resistance

    NASA Astrophysics Data System (ADS)

    Artemova, Tatiana; Gerardin, Ylaine; Hsin-Jung Li, Sophia; Gore, Jeff

    2011-03-01

    Since the discovery of penicillin, antibiotics have been our primary weapon against bacterial infections. Unfortunately, bacteria can gain resistance to penicillin by acquiring the gene that encodes beta-lactamase, which inactivates the antibiotic. However, mutations in this gene are necessary to degrade the modern antibiotic cefotaxime. Understanding the conditions that favor the spread of these mutations is a challenge. Here we show that bacterial growth in beta-lactam antibiotics is cooperative and that the nature of this growth determines the conditions in which resistance evolves. Quantitative analysis of the growth dynamics predicts a peak in selection at very low antibiotic concentrations; competition between strains confirms this prediction. We also find significant selection at higher antibiotic concentrations, close to the minimum inhibitory concentrations of the strains. Our results argue that an understanding of the evolutionary forces that lead to antibiotic resistance requires a quantitative understanding of the evolution of cooperation in bacteria.

  19. Resistance to antibiotics targeted to the bacterial cell wall.

    PubMed

    Nikolaidis, I; Favini-Stabile, S; Dessen, A

    2014-03-01

    Peptidoglycan is the main component of the bacterial cell wall. It is a complex, three-dimensional mesh that surrounds the entire cell and is composed of strands of alternating glycan units crosslinked by short peptides. Its biosynthetic machinery has been, for the past five decades, a preferred target for the discovery of antibacterials. Synthesis of the peptidoglycan occurs sequentially within three cellular compartments (cytoplasm, membrane, and periplasm), and inhibitors of proteins that catalyze each stage have been identified, although not all are applicable for clinical use. A number of these antimicrobials, however, have been rendered inactive by resistance mechanisms. The employment of structural biology techniques has been instrumental in the understanding of such processes, as well as the development of strategies to overcome them. This review provides an overview of resistance mechanisms developed toward antibiotics that target bacterial cell wall precursors and its biosynthetic machinery. Strategies toward the development of novel inhibitors that could overcome resistance are also discussed.

  20. [Effect of Three Typical Disinfection Byproducts on Bacterial Antibiotic Resistance].

    PubMed

    Lü, Lu; Zhang, Meng-lu; Wang, Chun-ming; Lin, Hui-rong; Yu, Xin

    2015-07-01

    The effect of typical disinfection byproducts (DBPs) on bacterial antibiotic resistance was investigated in this study. chlorodibromomethane (CDBM), iodoacetic acid (IAA) and chloral hydrate (CH) were selected, which belong to trihalomethanes (THMs), haloacetic acids (HAAs) and aldehydes, respectively. After exposure to the selected DBPs, the resistance change of the tested strains to antibiotics was determined. As a result, all of the three DBPs induced Pseudomonas aeruginosa PAO1 to gain increased resistance to the five antibiotics tested, and the DBPs ranked as IAA > CH > CDBM according to their enhancement effects. Multidrug resistance could also be enhanced by treatment with IAA. The same result was observed in Escherichia coli K12, suggesting that the effect of DBPs on antibiotic resistance was a common phenomenon. The mechanism was probably that DBPs stimulated oxidative stress, which induced mutagenesis. And the antibiotic resistance mutation frequency could be increased along with mutagenesis. This study revealed that the acquisition of bacterial antibiotic resistance might be related to DBPs in drinking water systems. Besides the genotoxicological risks, the epidemiological risks of DBPs should not be overlooked.

  1. Bacterial resistance to Quaternary Ammonium Compounds (QAC) disinfectants.

    PubMed

    Bragg, Robert; Jansen, Arina; Coetzee, Marisa; van der Westhuizen, Wouter; Boucher, Charlotte

    2014-01-01

    Control of bacterial diseases has, for many years, been dependent on the use of antibiotics. Due to the high levels of efficacy of antibiotics in the past other disease control options have, to a large extent, been neglected. Mankind is now facing an increasing problem with antibiotic resistance. In an effort to retain some antibiotics for human use, there are moves afoot to limit or even ban the use of antibiotics in animal production. The use of antibiotics as growth promoters have been banned in the European Union and the USA. The potential ban on the use of antibiotics to treat diseases in production animals creates a dilemma for man-suffer significant problem with bacterial infection or suffer from a severe shortage of food! There are other options for the control of bacterial diseases. These include vaccine development, bacteriophage therapy, and improved biosecurity. Vaccine development against bacterial pathogens, particularly opportunistic pathogens, is often very challenging, as in many cases the molecular basis of the virulence is not always clearly understood. This is particularly true for Escherichia coli. Biosecurity (disinfection) has been a highly neglected area in disease control. With the ever-increasing problems with antibiotic resistance-the focus should return to improvements in biosecurity. As with antibiotics, bacteria also have mechanisms for resistance to disinfectants. To ensure that we do not replace one set of problems (increasing antibiotic resistance) with another (increasing resistance to disinfectants) we need to fully understand the modes of action of disinfectants and how the bacteria develop resistance to these disinfectants. Molecular studies have been undertaken to relate the presence of QAC resistance genes in bacteria to their levels of sensitivity to different generations of QAC-based products. The mode of action of QAC on bacteria has been studied using NanoSAM technology, where it was revealed that the QAC causes disruption

  2. Bacterial resistance to arsenic protects against protist killing.

    PubMed

    Hao, Xiuli; Li, Xuanji; Pal, Chandan; Hobman, Jon; Larsson, D G Joakim; Saquib, Quaiser; Alwathnani, Hend A; Rosen, Barry P; Zhu, Yong-Guan; Rensing, Christopher

    2017-04-01

    Protists kill their bacterial prey using toxic metals such as copper. Here we hypothesize that the metalloid arsenic has a similar role. To test this hypothesis, we examined intracellular survival of Escherichia coli (E. coli) in the amoeba Dictyostelium discoideum (D. discoideum). Deletion of the E. coli ars operon led to significantly lower intracellular survival compared to wild type E. coli. This suggests that protists use arsenic to poison bacterial cells in the phagosome, similar to their use of copper. In response to copper and arsenic poisoning by protists, there is selection for acquisition of arsenic and copper resistance genes in the bacterial prey to avoid killing. In agreement with this hypothesis, both copper and arsenic resistance determinants are widespread in many bacterial taxa and environments, and they are often found together on plasmids. A role for heavy metals and arsenic in the ancient predator-prey relationship between protists and bacteria could explain the widespread presence of metal resistance determinants in pristine environments.

  3. Essential Oils, A New Horizon in Combating Bacterial Antibiotic Resistance

    PubMed Central

    Yap, Polly Soo Xi; Yiap, Beow Chin; Ping, Hu Cai; Lim, Swee Hua Erin

    2014-01-01

    For many years, the battle between humans and the multitudes of infection and disease causing pathogens continues. Emerging at the battlefield as some of the most significant challenges to human health are bacterial resistance and its rapid rise. These have become a major concern in global public health invigorating the need for new antimicrobial compounds. A rational approach to deal with antibiotic resistance problems requires detailed knowledge of the different biological and non-biological factors that affect the rate and extent of resistance development. Combination therapy combining conventional antibiotics and essential oils is currently blooming and represents a potential area for future investigations. This new generation of phytopharmaceuticals may shed light on the development of new pharmacological regimes in combating antibiotic resistance. This review consolidated and described the observed synergistic outcome between essential oils and antibiotics, and highlighted the possibilities of essential oils as the potential resistance modifying agent. PMID:24627729

  4. [Genetics and genomics for the study of bacterial resistance].

    PubMed

    Garza-Ramos, Ulises; Silva-Sánchez, Jesús; Martínez-Romero, Esperanza

    2009-01-01

    Bacterial resistance is a public health problem causing high rates of morbidity and mortality in hospital settings. To the extent that different antibiotics are used, bacteria resistant to multiple drugs are selected. The development of new molecular genomic and proteomic tools such as real-time PCR, DNA pyrosequencing, mass spectrometry, DNA microarrays, and bioinformatics allow for more in-depth knowledge about the physiology and structure of bacteria and mechanisms involved in antibiotic resistance. These studies identify new targets for drugs and design specific antibiotics to provide more accurate treatments to combat infections caused by bacteria. Using these techniques, it will also be possible to rapidly identify genes that confer resistance to antibiotics, and to identify complex genetic structures, such as integrons that are involved in the spread of genes that confer multidrug-resistance.

  5. New Technologies for Rapid Bacterial Identification and Antibiotic Resistance Profiling.

    PubMed

    Kelley, Shana O

    2017-04-01

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

  6. PARAMETERS OF TREATED STAINLESS STEEL SURFACES IMPORTANT FOR RESISTANCE TO BACTERIAL CONTAMINATION

    EPA Science Inventory

    Use of materials that are resistant to bacterial contamination could enhance food safety during processing. Common finishing treatments of stainless steel surfaces used for components of poultry processing equipment were tested for resistance to bacterial attachment. Surface char...

  7. 75 FR 33317 - Antibacterial Resistance and Diagnostic Device and Drug Development Research for Bacterial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-11

    ... HUMAN SERVICES Food and Drug Administration Antibacterial Resistance and Diagnostic Device and Drug... resistance, rapid diagnostic device development for bacterial diseases, and antibacterial drug development. The workshop will address antibacterial drug resistance, mechanisms of resistance, epidemiology...

  8. Differential resistance of drinking water bacterial populations to monochloramine disinfection.

    PubMed

    Chiao, Tzu-Hsin; Clancy, Tara M; Pinto, Ameet; Xi, Chuanwu; Raskin, Lutgarde

    2014-04-01

    The impact of monochloramine disinfection on the complex bacterial community structure in drinking water systems was investigated using culture-dependent and culture-independent methods. Changes in viable bacterial diversity were monitored using culture-independent methods that distinguish between live and dead cells based on membrane integrity, providing a highly conservative measure of viability. Samples were collected from lab-scale and full-scale drinking water filters exposed to monochloramine for a range of contact times. Culture-independent detection of live cells was based on propidium monoazide (PMA) treatment to selectively remove DNA from membrane-compromised cells. Quantitative PCR (qPCR) and pyrosequencing of 16S rRNA genes was used to quantify the DNA of live bacteria and characterize the bacterial communities, respectively. The inactivation rate determined by the culture-independent PMA-qPCR method (1.5-log removal at 664 mg·min/L) was lower than the inactivation rate measured by the culture-based methods (4-log removal at 66 mg·min/L). Moreover, drastic changes in the live bacterial community structure were detected during monochloramine disinfection using PMA-pyrosequencing, while the community structure appeared to remain stable when pyrosequencing was performed on samples that were not subject to PMA treatment. Genera that increased in relative abundance during monochloramine treatment include Legionella, Escherichia, and Geobacter in the lab-scale system and Mycobacterium, Sphingomonas, and Coxiella in the full-scale system. These results demonstrate that bacterial populations in drinking water exhibit differential resistance to monochloramine, and that the disinfection process selects for resistant bacterial populations.

  9. Synthesis of Multimetal-Graphene Composite by Mechanical Milling

    NASA Astrophysics Data System (ADS)

    Saiphaneendra, Bachu; Srivastava, Avi Krishna; Srivastava, Chandan

    2016-10-01

    Multimetal-graphene composites were synthesized using the ball milling technique. To prepare the composite, graphite powder was mixed with Fe, Cr, Co, Cu and Mg powders. This mixture was then mechanically milled for 35 h in toluene medium. After milling, the multimetal-graphite mixture was mixed with sodium lauryl sulfate and sonicated for 2 h. Sonication led to the exfoliation of graphene sheets. Formation of graphene was confirmed from x-ray diffraction and Raman spectroscopy. Transmission electron microscopy-based analysis revealed the formation of multimetal deposits over the graphene surface. Compositional analysis of the multimetal deposits revealed fairly uniform distribution of all the five component metal atoms over the graphene sheet. The average composition of the multimetal deposit was determined to be 11.4 ± 4 at.% Mg, 33.8 ± 19 at.% Cr, 21.8 ± 16 at.% Fe, 9.4 ± 5.7 at.% Co and 23.6 ± 12 at.% Cu.

  10. Population Dynamics of Patients with Bacterial Resistance in Hospital Environment

    PubMed Central

    Qu, Leilei; Pan, Qiuhui; Gao, Xubin; He, Mingfeng

    2016-01-01

    During the past decades, the increase of antibiotic resistance has become a major concern worldwide. The researchers found that superbugs with new type of resistance genes (NDM-1) have two aspects of transmission characteristics; the first is that the antibiotic resistance genes can horizontally transfer among bacteria, and the other is that the superbugs can spread between humans through direct contact. Based on these two transmission mechanisms, we study the dynamics of population in hospital environment where superbugs exist. In this paper, we build three mathematic models to illustrate the dynamics of patients with bacterial resistance in hospital environment. The models are analyzed using stability theory of differential equations. Positive equilibrium points of the system are investigated and their stability analysis is carried out. Moreover, the numerical simulation of the proposed model is also performed which supports the theoretical findings. PMID:26904150

  11. Population Dynamics of Patients with Bacterial Resistance in Hospital Environment.

    PubMed

    Qu, Leilei; Pan, Qiuhui; Gao, Xubin; He, Mingfeng

    2016-01-01

    During the past decades, the increase of antibiotic resistance has become a major concern worldwide. The researchers found that superbugs with new type of resistance genes (NDM-1) have two aspects of transmission characteristics; the first is that the antibiotic resistance genes can horizontally transfer among bacteria, and the other is that the superbugs can spread between humans through direct contact. Based on these two transmission mechanisms, we study the dynamics of population in hospital environment where superbugs exist. In this paper, we build three mathematic models to illustrate the dynamics of patients with bacterial resistance in hospital environment. The models are analyzed using stability theory of differential equations. Positive equilibrium points of the system are investigated and their stability analysis is carried out. Moreover, the numerical simulation of the proposed model is also performed which supports the theoretical findings.

  12. Screening Rice Cultivars for Resistance to Bacterial Leaf Blight.

    PubMed

    Fred, Agaba Kayihura; Kiswara, Gilang; Yi, Gihwan; Kim, Kyung-Min

    2016-05-28

    Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious threats to rice production. In this study, screening of rice for resistance to BLB was carried out at two different times and locations; that is, in a greenhouse during winter and in an open field during summer. The pathogenicity of Xoo race K1 was tested on 32 Korean rice cultivars. Inoculation was conducted at the maximum tillering stage, and the lesion length was measured after 14 days of inoculation. Five cultivars, Hanareum, Namcheon, Samgdeok, Samgang, and Yangjo, were found to be resistant in both the greenhouse and open-field screenings. Expression of the plant defense-related genes JAmyb, OsNPR1, OsPR1a, OsWRKY45, and OsPR10b was observed in resistant and susceptible cultivars by qRT-PCR. Among the five genes tested, only OsPR10b showed coherent expression with the phenotypes. Screening of resistance to Xoo in rice was more accurate when conducted in open fields in the summer cultivation period than in greenhouses in winter. The expression of plant defenserelated genes after bacterial inoculation could give another perspective in elucidating defense mechanisms by using both resistant and susceptible individuals.

  13. Absence of bacterial resistance following repeat exposure to photodynamic therapy

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    The prevalence of antibiotic resistant bacteria necessitates exploration of alternative approaches to treat hospital and community acquired infections. The aim of this study was to determine whether bacterial pathogens develop resistance to antimicrobial photodynamic therapy (aPDT) during repeated sub-lethal challenge. Antibiotic sensitive and resistant strains of S. aureus and antibiotic sensitive E. coli were subjected to repeat PDT treatments using a methylene blue photosensitizer formulation and 670 nm illumination from a non-thermal diode laser. Parameters were adjusted such that kills were <100% so that surviving colonies could be passaged for subsequent exposures. With each repeat, kills were compared to those using non-exposed cultures of the same strain. Oxacillin resistance was induced in S. aureus using a disc diffusion method. For each experiment, "virgin" and "repeat" cultures were exposed to methylene blue at 0.01% w/v and illuminated with an energy dose of 20.6 J/cm2. No significant difference in killing of E. coli (repeat vs. virgin culture) was observed through 11 repeat exposures. Similar results were seen using MSSA and MRSA, wherein kill rate did not significantly differ from control over 25 repeat exposures. In contrast, complete oxacillin resistance could be generated in S. aureus over a limited number of exposures. PDT is effective in the eradication of pathogens including antibiotic resistance strains. Furthermore, repeated sub-lethal exposure does not induce resistance to subsequent PDT treatments. The absence of resistance formation represents a significant advantage of PDT over traditional antibiotics.

  14. Bacterial cheating limits the evolution of antibiotic resistance

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    The widespread use of antibiotics has led to the evolution of resistance in bacteria. Bacteria can gain resistance to the antibiotic ampicillin by acquiring a plasmid carrying the gene beta-lactamase, which inactivates the antibiotic. This inactivation may represent a cooperative behavior, as the entire bacterial population benefits from removing the antibiotic. The cooperative nature of this growth suggests that a cheater strain--which does not contribute to breaking down the antibiotic--may be able to take advantage of cells cooperatively inactivating the antibiotic. Here we experimentally find that a ``sensitive'' bacterial strain lacking the plasmid conferring resistance can invade a population of resistant bacteria, even in antibiotic concentrations that should kill the sensitive strain. We observe stable coexistence between the two strains and find that a simple model successfully explains the behavior as a function of antibiotic concentration and cell density. We anticipate that our results will provide insight into the evolutionary origin of phenotypic diversity and cooperative behaviors found in nature.

  15. Drug resistance analysis of bacterial strains isolated from burn patients.

    PubMed

    Wang, L F; Li, J L; Ma, W H; Li, J Y

    2014-01-22

    This study aimed to analyze the spectrum and drug resistance of bacteria isolated from burn patients to provide a reference for rational clinical use of antibiotics. Up to 1914 bacterial strain specimens isolated from burn patients admitted to hospital between 2001 and 2010 were subjected to resistance monitoring by using the K-B paper disk method. Retrospective analysis was performed on drug resistance analysis of burn patients. The top eight bacterium strains according to detection rate. A total of 1355 strains of Gram-negative (G(-)) bacteria and 559 strains of Gram-positive (G(+)) bacteria were detected. The top eight bacterium strains, according to detection rate, were Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae, Enterobacter cloacae, and Enterococcus. Drug resistance rates were higher than 90% in A. baumannii, P. aeruginosa, S. epidermidis, and S. aureus, which accounted for 52.2, 21.7, 27.8, and 33.3%, respectively, of the entire sample. Those with drug resistance rates lower than 30% accounted for 4.3, 30.4, 16.7, and 16.7%, respectively. Multidrug-resistant S. aureus (MRSA) and methicillin-resistant S. epidermidis (MRSE) accounted for 49.2 and 76.4% of the S. epidermis and S. aureus resistance, respectively. Antibacterial drugs that had drug resistance rates to MRSE and MRSA higher than 90% accounted for 38.9 and 72.2%, respectively, whereas those with lower than 30% drug resistance rates accounted for 11.1 and 16.7%, respectively. The burn patients enrolled in the study were mainly infected with G(-) bacteria. These results strongly suggest that clinicians should practice rational use of antibiotics based on drug susceptibility test results.

  16. Experimental quantum multimeter and one-qubit fingerprinting

    SciTech Connect

    Du Jiangfeng; Zou Ping; Peng Xinhua; Oi, Daniel K. L.; Ekert, Artur; Kwek, L. C.; Oh, C. H.

    2006-10-15

    There has been much recent effort to realize quantum devices in many different physical systems. Among them, nuclear magnetic resonance (NMR) has been the first to demonstrate nontrivial quantum algorithms with small numbers of qubits and hence is a prototype for the key ingredients needed to build quantum computers. An important building block in many quantum applications is the scattering circuit, which can be used as a quantum multimeter to perform various quantum information processing tasks directly without recourse to quantum tomography. We implement in NMR a three-qubit version of the multimeter and also demonstrate a single-qubit fingerprinting.

  17. QTLs for Resistance to Major Rice Diseases Exacerbated by Global Warming: Brown Spot, Bacterial Seedling Rot, and Bacterial Grain Rot.

    PubMed

    Mizobuchi, Ritsuko; Fukuoka, Shuichi; Tsushima, Seiya; Yano, Masahiro; Sato, Hiroyuki

    2016-12-01

    In rice (Oryza sativa L.), damage from diseases such as brown spot, caused by Bipolaris oryzae, and bacterial seedling rot and bacterial grain rot, caused by Burkholderia glumae, has increased under global warming because the optimal temperature ranges for growth of these pathogens are relatively high (around 30 °C). Therefore, the need for cultivars carrying genes for resistance to these diseases is increasing to ensure sustainable rice production. In contrast to the situation for other important rice diseases such as blast and bacterial blight, no genes for complete resistance to brown spot, bacterial seedling rot or bacterial grain rot have yet been discovered. Thus, rice breeders have to use partial resistance, which is largely influenced by environmental conditions. Recent progress in molecular genetics and improvement of evaluation methods for disease resistance have facilitated detection of quantitative trait loci (QTLs) associated with resistance. In this review, we summarize the results of worldwide screening for cultivars with resistance to brown spot, bacterial seedling rot and bacterial grain rot and we discuss the identification of QTLs conferring resistance to these diseases in order to provide useful information for rice breeding programs.

  18. MOCVD of multimetal and noble metal films

    NASA Astrophysics Data System (ADS)

    Endle, James Patrick

    2000-11-01

    Carbon content in TiN films produced with tetrakis(dimethylamino)titanium (TDMAT) and methylhydrazine or dimethylhydrazine can be controlled at or below 10% with a N/Ti ratio of ˜1.3 at growth temperatures between 573 and 723 K. Post-dosing either hydrazine on a CVD TiN film results in additional N-Ti bonds, indicating a surface reaction between the two precursors occurs. Co-dosing hydrazine-like compounds with larger alkyl ligands than methyl resulted in additional carbon incorporation in the TiN film. A growth system, consisting of a load lock and growth chamber, and a precursor pyrolysis system were designed and built to study metalorganic chemical vapor deposition. Addition of a bubbler and a direct liquid injection system allowed for the vaporization of solid and liquid precursors and solutions of multiple precursors. A precursor pyrolysis system was designed for high and low vapor pressure precursors and high carrier gas flow rates. The systems were used to study (Al,Ti)N and Ir film growth. (Al,Ti)N was used as a template to study the incorporation of elements into a multimetal chemical vapor deposited film using NH3 and a DLI solution of TDMAT and the tris(dimethylarnino)alane dimer (TDMAA) in toluene-NH 3 significantly decreases the decomposition temperature of both precursors. Carbon was reduced by increasing the NH3 partial pressure, and the Al incorporation was increased by increasing the TDMAA/TDMAT ratio in the DLI solution. Exposure to ambient resulted in significant oxygen incorporation and the removal of carbon and nitrogen from the (AI,Ti)N film. Conformal (AI,Ti)N films were produced at 450 K in the presence of NH3 and at 550 K without NH3. The role of O2 in Ir film growth was studied with the newly designed equipment. O2 significantly decreases the decomposition temperature of (MeCp)Ir(COD) below 425 K by preventing a carbonaceous build-up on the iridium film. By decreasing the oxygen partial pressure, the island nucleation and coalescence

  19. Antibiotic resistance in prevalent bacterial and protozoan sexually transmitted infections

    PubMed Central

    Krupp, Karl; Madhivanan, Purnima

    2015-01-01

    The emergence of multi-drug resistant sexually transmitted infections (STIs) is causing a treatment crisis across the globe. While cephalosporin-resistant gonorrhea is one of the most pressing issues, extensively antibiotic resistant Chlamydia trachomatis and Mycoplasma hominis are also becoming commonplace. Experts have suggested that the failure of current treatment regimens are “largely inevitable” and have called for entirely new classes of antimicrobial agents. With the exception of several new classes of drugs primarily targeting nosocomial infections, progress has been slow. While pharmaceutical companies continue to introduce new drugs, they are based on decade-old discoveries. While there is disagreement about what constitutes new classes of antibiotics, many experts suggest that the last truly new family of antimicrobials was discovered in 1987. This review summarizes the existing literature on antibiotic resistance in common bacterial and protozoal STIs. It also briefly discusses several of the most promising alternatives to current therapies, and further examines how advances in drug delivery, formulation, concentration, and timing are improving the efficacy of existing treatments. Finally, the paper discusses the current state of pharmaceutical development for multidrug-resistant STI. PMID:26392647

  20. Rapid methods for detection of bacterial resistance to antibiotics.

    PubMed

    March-Rosselló, Gabriel Alberto

    2017-03-01

    The most widely used antibiotic susceptibility testing methods in Clinical Microbiology are based on the phenotypic detection of antibiotic resistance by measuring bacterial growth in the presence of the antibiotic being tested. These conventional methods take typically 24hours to obtain results. Here we review the main techniques for rapid determination of antibiotic susceptibility. Data obtained with different methods such as molecular techniques, microarrays, commercial methods used in work routine, immunochromatographic methods, colorimetric methods, image methods, nephelometry, MALDI-TOF mass spectrometry, flow cytometry, chemiluminescence and bioluminescence, microfluids and methods based on cell disruption are analysed in detail.

  1. Evaluation of Glyphosate-Resistant Soybean Cultivars for Resistance to Bacterial Pustule

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xanthomonas axonopodis pv. glycines causes bacterial pustule of soybean, which is a common disease in many soybean-growing areas of the world and is controlled by a single recessive gene that was commonly found in many conventional glyphosate-sensitive soybean cultivars. Since glyphosate-resistant c...

  2. How to Measure Export via Bacterial Multidrug Resistance Efflux Pumps

    PubMed Central

    Blair, Jessica M. A.

    2016-01-01

    ABSTRACT Bacterial multidrug resistance (MDR) efflux pumps are an important mechanism of antibiotic resistance and are required for many pathogens to cause infection. They are also being harnessed to improve microbial biotechnological processes, including biofuel production. Therefore, scientists of many specialties must be able to accurately measure efflux activity. However, myriad methodologies have been described and the most appropriate method is not always clear. Within the scientific literature, many methods are misused or data arising are misinterpreted. The methods for measuring efflux activity can be split into two groups, (i) those that directly measure efflux and (ii) those that measure the intracellular accumulation of a substrate, which is then used to infer efflux activity. Here, we review the methods for measuring efflux and explore the most recent advances in this field, including single-cell or cell-free technologies and mass spectrometry, that are being used to provide more detailed information about efflux pump activity. PMID:27381291

  3. Sterilization Resistance of Bacterial Spores Explained with Water Chemistry.

    PubMed

    Friedline, Anthony W; Zachariah, Malcolm M; Middaugh, Amy N; Garimella, Ravindranath; Vaishampayan, Parag A; Rice, Charles V

    2015-11-05

    Bacterial spores can survive for long periods without nutrients and in harsh environmental conditions. This survival is influenced by the structure of the spore, the presence of protective compounds, and water retention. These compounds, and the physical state of water in particular, allow some species of bacterial spores to survive sterilization schemes with hydrogen peroxide and UV light. The chemical nature of the spore core and its water has been a subject of some contention and the chemical environment of the water impacts resistance paradigms. Either the spore has a glassy core, where water is immobilized along with other core components, or the core is gel-like with mobile water diffusion. These properties affect the movement of peroxide and radical species, and hence resistance. Deuterium solid-state NMR experiments are useful for examining the nature of the water inside the spore. Previous work in our lab with spores of Bacillus subtilis indicate that, for spores, the core water is in a more immobilized state than expected for the gel-like core theory, suggesting a glassy core environment. Here, we report deuterium solid-state NMR observations of the water within UV- and peroxide-resistant spores from Bacillus pumilus SAFR-032. Variable-temperature NMR experiments indicate no change in the line shape after heating to 50 °C, but an overall decrease in signal after heating to 100 °C. These results show glass-like core dynamics within B. pumilus SAFR-032 that may be the potential source of its known UV-resistance properties. The observed NMR traits can be attributed to the presence of an exosporium containing additional labile deuterons that can aid in the deactivation of sterilizing agents.

  4. Antifungal agents: mode of action, mechanisms of resistance, and correlation of these mechanisms with bacterial resistance.

    PubMed

    Ghannoum, M A; Rice, L B

    1999-10-01

    The increased use of antibacterial and antifungal agents in recent years has resulted in the development of resistance to these drugs. The significant clinical implication of resistance has led to heightened interest in the study of antimicrobial resistance from different angles. Areas addressed include mechanisms underlying this resistance, improved methods to detect resistance when it occurs, alternate options for the treatment of infections caused by resistant organisms, and strategies to prevent and control the emergence and spread of resistance. In this review, the mode of action of antifungals and their mechanisms of resistance are discussed. Additionally, an attempt is made to discuss the correlation between fungal and bacterial resistance. Antifungals can be grouped into three classes based on their site of action: azoles, which inhibit the synthesis of ergosterol (the main fungal sterol); polyenes, which interact with fungal membrane sterols physicochemically; and 5-fluorocytosine, which inhibits macromolecular synthesis. Many different types of mechanisms contribute to the development of resistance to antifungals. These mechanisms include alteration in drug target, alteration in sterol biosynthesis, reduction in the intercellular concentration of target enzyme, and overexpression of the antifungal drug target. Although the comparison between the mechanisms of resistance to antifungals and antibacterials is necessarily limited by several factors defined in the review, a correlation between the two exists. For example, modification of enzymes which serve as targets for antimicrobial action and the involvement of membrane pumps in the extrusion of drugs are well characterized in both the eukaryotic and prokaryotic cells.

  5. The Assembly Motif of a Bacterial Small Multidrug Resistance Protein*

    PubMed Central

    Poulsen, Bradley E.; Rath, Arianna; Deber, Charles M.

    2009-01-01

    Multidrug transporters such as the small multidrug resistance (SMR) family of bacterial integral membrane proteins are capable of conferring clinically significant resistance to a variety of common therapeutics. As antiporter proteins of ∼100 amino acids, SMRs must self-assemble into homo-oligomeric structures for efflux of drug molecules. Oligomerization centered at transmembrane helix four (TM4) has been implicated in SMR assembly, but the full complement of residues required to mediate its self-interaction remains to be characterized. Here, we use Hsmr, the 110-residue SMR family member of the archaebacterium Halobacterium salinarum, to determine the TM4 residue motif required to mediate drug resistance and SMR self-association. Twelve single point mutants that scan the central portion of the TM4 helix (residues 85–104) were constructed and were tested for their ability to confer resistance to the cytotoxic compound ethidium bromide. Six residues were found to be individually essential for drug resistance activity (Gly90, Leu91, Leu93, Ile94, Gly97, and Val98), defining a minimum activity motif of 90GLXLIXXGV98 within TM4. When the propensity of these mutants to dimerize on SDS-PAGE was examined, replacements of all but Ile resulted in ∼2-fold reduction of dimerization versus the wild-type antiporter. Our work defines a minimum activity motif of 90GLXLIXXGV98 within TM4 and suggests that this sequence mediates TM4-based SMR dimerization along a single helix surface, stabilized by a small residue heptad repeat sequence. These TM4-TM4 interactions likely constitute the highest affinity locus for disruption of SMR function by directly targeting its self-assembly mechanism. PMID:19224913

  6. Antiplasmid activity: loss of bacterial resistance to antibiotics.

    PubMed

    Molnár, J; Földeák, S; Nakamura, M J; Rausch, H; Domonkos, K; Szabó, M

    1992-01-01

    The antiplasmid activity of tricyclic compounds, e.g. phenothiazines, dibenzoazepines, dibenzocykloheptene derivatives and some stereoisomers, was shown on E. coli in vitro. Some ring-substituted phenothiazine and cannabis derivatives had only an antibacterial effect. Promethazine, a selected phenothiazine, cured antibiotic resistance and lactose fermentation of E.coli, tumour inducing ability of Agrobacterium tumefaciens and nodule formation of Rhizobium meliloti. Plasmids of different E.coli strains were eliminated with varying frequency. The antiplasmid activity of the compounds can be due to the increased membrane permeability. Inhibition of DNA gyrase and complex formation with the supercoiled form of plasmid DNA can lead to the cessation of plasmid replication in the bacterial cells. In addition, in vivo plasmid curing was demonstrated at a low frequency.

  7. Monopoly pricing of an antibiotic subject to bacterial resistance.

    PubMed

    Herrmann, Markus

    2010-01-01

    We develop a dynamic bio-economic model of bacterial resistance and disease transmission in which we characterize the pricing policy of a monopolist who is protected by a patent. After expiration, the monopolist behaves competitively in a generic industry having open access to the common pool of antibiotic efficacy and infection. The monopolist manages endogenously the levels of antibiotic efficacy as well as the infected population, which represent quality and market size respectively and achieves, at least temporarily, higher such levels than a hypothetically myopic monopolist who does not take into account the dynamic externalities. The pricing policy and the biological system is characterized by the turnpike property. Before the patent vanishes, the monopolist behaves more and more myopically, leading to a continuous decrease in the price of the antibiotic. Once the generic industry takes over, a discontinuous fall in price occurs. Whether a prolongation of the patent is socially desirable depends on the relative levels of antibiotic efficacy and infection.

  8. Modulation of Bacterial Multidrug Resistance Efflux Pumps of the Major Facilitator Superfamily

    PubMed Central

    Kumar, Sanath; Mukherjee, Mun Mun; Varela, Manuel F.

    2013-01-01

    Bacterial infections pose a serious public health concern, especially when an infectious disease has a multidrug resistant causative agent. Such multidrug resistant bacteria can compromise the clinical utility of major chemotherapeutic antimicrobial agents. Drug and multidrug resistant bacteria harbor several distinct molecular mechanisms for resistance. Bacterial antimicrobial agent efflux pumps represent a major mechanism of clinical resistance. The major facilitator superfamily (MFS) is one of the largest groups of solute transporters to date and includes a significant number of bacterial drug and multidrug efflux pumps. We review recent work on the modulation of multidrug efflux pumps, paying special attention to those transporters belonging primarily to the MFS. PMID:25750934

  9. Bacterial Resistance to Antisense Peptide Phosphorodiamidate Morpholino Oligomers

    PubMed Central

    Puckett, Susan E.; Reese, Kaleb A.; Mitev, Georgi M.; Mullen, Valerie; Johnson, Rudd C.; Pomraning, Kyle R.; Mellbye, Brett L.; Tilley, Lucas D.; Iversen, Patrick L.; Freitag, Michael

    2012-01-01

    Peptide phosphorodiamidate morpholino oligomers (PPMOs) are synthetic DNA mimics that bind cRNA and inhibit bacterial gene expression. The PPMO (RFF)3RXB-AcpP (where R is arginine, F, phenylalanine, X is 6-aminohexanoic acid, B is β-alanine, and AcpP is acyl carrier protein) is complementary to 11 bases of the essential gene acpP (which encodes acyl carrier protein). The MIC of (RFF)3RXB-AcpP was 2.5 μM (14 μg/ml) in Escherichia coli W3110. The rate of spontaneous resistance of E. coli to (RFF)3RXB-AcpP was 4 × 10−7 mutations/cell division. A spontaneous (RFF)3RXB-AcpP-resistant mutant (PR200.1) was isolated. The MIC of (RFF)3RXB-AcpP was 40 μM (224 μg/ml) for PR200.1. The MICs of standard antibiotics for PR200.1 and W3110 were identical. The sequence of acpP was identical in PR200.1 and W3110. PR200.1 was also resistant to other PPMOs conjugated to (RFF)3RXB or peptides with a similar composition or pattern of cationic and nonpolar residues. Genomic sequencing of PR200.1 identified a mutation in sbmA, which encodes an active transport protein. In separate experiments, a (RFF)3RXB-AcpP-resistant isolate (RR3) was selected from a transposome library, and the insertion was mapped to sbmA. Genetic complementation of PR200.1 or RR3 with sbmA restored susceptibility to (RFF)3RXB-AcpP. Deletion of sbmA caused resistance to (RFF)3RXB-AcpP. We conclude that resistance to (RFF)3RXB-AcpP was linked to the peptide and not the phosphorodiamidate morpholino oligomer, dependent on the composition or repeating pattern of amino acids, and caused by mutations in sbmA. The data further suggest that (RFF)3R-XB PPMOs may be transported across the plasma membrane by SbmA. PMID:22985881

  10. Bacterial resistance to antisense peptide phosphorodiamidate morpholino oligomers.

    PubMed

    Puckett, Susan E; Reese, Kaleb A; Mitev, Georgi M; Mullen, Valerie; Johnson, Rudd C; Pomraning, Kyle R; Mellbye, Brett L; Tilley, Lucas D; Iversen, Patrick L; Freitag, Michael; Geller, Bruce L

    2012-12-01

    Peptide phosphorodiamidate morpholino oligomers (PPMOs) are synthetic DNA mimics that bind cRNA and inhibit bacterial gene expression. The PPMO (RFF)(3)RXB-AcpP (where R is arginine, F, phenylalanine, X is 6-aminohexanoic acid, B is β-alanine, and AcpP is acyl carrier protein) is complementary to 11 bases of the essential gene acpP (which encodes acyl carrier protein). The MIC of (RFF)(3)RXB-AcpP was 2.5 μM (14 μg/ml) in Escherichia coli W3110. The rate of spontaneous resistance of E. coli to (RFF)(3)RXB-AcpP was 4 × 10(-7) mutations/cell division. A spontaneous (RFF)(3)RXB-AcpP-resistant mutant (PR200.1) was isolated. The MIC of (RFF)(3)RXB-AcpP was 40 μM (224 μg/ml) for PR200.1. The MICs of standard antibiotics for PR200.1 and W3110 were identical. The sequence of acpP was identical in PR200.1 and W3110. PR200.1 was also resistant to other PPMOs conjugated to (RFF)(3)RXB or peptides with a similar composition or pattern of cationic and nonpolar residues. Genomic sequencing of PR200.1 identified a mutation in sbmA, which encodes an active transport protein. In separate experiments, a (RFF)(3)RXB-AcpP-resistant isolate (RR3) was selected from a transposome library, and the insertion was mapped to sbmA. Genetic complementation of PR200.1 or RR3 with sbmA restored susceptibility to (RFF)(3)RXB-AcpP. Deletion of sbmA caused resistance to (RFF)(3)RXB-AcpP. We conclude that resistance to (RFF)(3)RXB-AcpP was linked to the peptide and not the phosphorodiamidate morpholino oligomer, dependent on the composition or repeating pattern of amino acids, and caused by mutations in sbmA. The data further suggest that (RFF)(3)R-XB PPMOs may be transported across the plasma membrane by SbmA.

  11. Management of febrile neutropenia in the era of bacterial resistance

    PubMed Central

    Alp, Sehnaz

    2013-01-01

    Managing cancer patients with fever and neutropenia must be considered as a medical emergency since any delay in initiating appropriate empirical antibacterial therapy may result in high rates of mortality and morbidity. Emerging antibacterial resistance in bacterial pathogens infecting febrile neutropenic patients complicates management, and choosing the type of empirical antimicrobial therapy has become a challenge. To further complicate the decision process, not all neutropenic patients are in same category of susceptibility to develop severe infection. While low-risk patients may be treated with oral antibiotics in the outpatient setting, high-risk patients usually need to be admitted to hospital and receive parenteral broad-spectrum antibiotics until the neutrophil levels recover. These strategies have recently been addressed in two international guidelines from the Infectious Diseases Society of America (IDSA) and the European Conference on Infections in Leukaemia (ECIL). This review gives a brief overview of current antimicrobial resistance problems and their effects in febrile neutropenic cancer patients by summarizing the suggestions from the IDSA and ECIL guidelines. PMID:25165543

  12. Molecular structure and dynamics in bacterial mercury resistance

    SciTech Connect

    Johs, Alexander; Shi, Liang; Miller, Susan M; Summers, Anne O; Liang, Liyuan

    2008-01-01

    Bacteria participate significantly in mercury transformation in natural and industrial environments. Previous studies have shown that bacterial mercury resistance is mediated by the mer operon, typically located on transposons or plasmids. It encodes specific genes that facilitate uptake of mercury species, cleavage of organomercurials, and reduction of Hg(II) to Hg(0). Expression of mer operon genes is regulated by MerR, a metal-responsive regulator protein on the level of transcription. In vitro studies have shown that MerR forms a non-transcribing pre-initiation complex with RNA polymerase and the promoter DNA. Binding of Hg(II) induces conformational changes in MerR and other components of the complex resulting in the transcription of mer operon genes. As part of ongoing investigations on allosteric conformational changes induced by Hg(II) in dimeric MerR, and the implications on the binding of RNA polymerase to the promoter of the mer operon, we applied small angle scattering to study the regulatory mechanism of MerR in the presence and absence of Hg(II). Our results show that in the presence of Hg(II) the MerR dimer undergoes a significant reorientation from a compact state to a conformation revealing two distinct domains. Bacterial reduction of Hg(II) can also occur at concentrations too low to induce mer operon functions. Dissimilatory metal reducing bacteria, such as Shewanella and Geobacter are able to reduce Hg(II) in the presence of mineral oxides. This process has been linked to the activity of outer membrane multiheme cytochromes. We isolated and purified a decaheme outer membrane cytochrome OmcA from Shewanella oneidensis MR-1 and characterized its envelope shape in solution by small angle x-ray scattering. Structural features were identified and compared to homology models. These results show that OmcA is an elongated macromolecule consisting of separate modules, which may be connected by flexible linkers.

  13. Understanding bacterial resistance to antimicrobial peptides: From the surface to deep inside.

    PubMed

    Maria-Neto, Simone; de Almeida, Keyla Caroline; Macedo, Maria Ligia Rodrigues; Franco, Octávio Luiz

    2015-11-01

    Resistant bacterial infections are a major health problem in many parts of the world. The major commercial antibiotic classes often fail to combat common bacteria. Although antimicrobial peptides are able to control bacterial infections by interfering with microbial metabolism and physiological processes in several ways, a large number of cases of resistance to antibiotic peptide classes have also been reported. To gain a better understanding of the resistance process various technologies have been applied. Here we discuss multiple strategies by which bacteria could develop enhanced antimicrobial peptide resistance, focusing on sub-cellular regions from the surface to deep inside, evaluating bacterial membranes, cell walls and cytoplasmic metabolism. Moreover, some high-throughput methods for antimicrobial resistance detection and discrimination are also examined. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.

  14. A computational model to monitor and predict trends in bacterial resistance.

    PubMed

    Alawieh, Ali; Sabra, Zahraa; Bizri, Abdul Rahman; Davies, Christopher; White, Roger; Zaraket, Fadi A

    2015-09-01

    Current concern over the emergence of multidrug-resistant superbugs has renewed interest in approaches that can monitor existing trends in bacterial resistance and make predictions of future trends. Recent advances in bacterial surveillance and the development of online repositories of susceptibility tests across wide geographical areas provide an important new resource, yet there are only limited computational tools for its exploitation. Here we propose a hybrid computational model called BARDmaps for automated analysis of antibacterial susceptibility tests from surveillance records and for performing future predictions. BARDmaps was designed to include a structural computational model that can detect patterns among bacterial resistance changes as well as a behavioural computational model that can use the detected patterns to predict future changes in bacterial resistance. Data from the European Antimicrobial Resistance Surveillance Network (EARS-Net) were used to validate and apply the model. BARDmaps was compared with standard curve-fitting approaches used in epidemiological research. Here we show that BARDmaps can reliably predict future trends in bacterial resistance across Europe. BARDmaps performed better than other curve-fitting approaches for predicting future resistance levels. In addition, BARDmaps was also able to detect abrupt changes in bacterial resistance in response to outbreaks and interventions as well as to compare bacterial behaviour across countries and drugs. In conclusion, BARDmaps is a reliable tool to automatically predict and analyse changes in bacterial resistance across Europe. We anticipate that BARDmaps will become an invaluable tool both for clinical providers and governmental agencies to help combat the threat posed by antibiotic-resistant bacteria.

  15. Antibiotic Capture by Bacterial Lipocalins Uncovers an Extracellular Mechanism of Intrinsic Antibiotic Resistance.

    PubMed

    El-Halfawy, Omar M; Klett, Javier; Ingram, Rebecca J; Loutet, Slade A; Murphy, Michael E P; Martín-Santamaría, Sonsoles; Valvano, Miguel A

    2017-03-14

    The potential for microbes to overcome antibiotics of different classes before they reach bacterial cells is largely unexplored. Here we show that a soluble bacterial lipocalin produced by Burkholderia cenocepacia upon exposure to sublethal antibiotic concentrations increases resistance to diverse antibiotics in vitro and in vivo These phenotypes were recapitulated by heterologous expression in B. cenocepacia of lipocalin genes from Pseudomonas aeruginosa, Mycobacterium tuberculosis, and methicillin-resistant Staphylococcus aureus Purified lipocalin bound different classes of bactericidal antibiotics and contributed to bacterial survival in vivo Experimental and X-ray crystal structure-guided computational studies revealed that lipocalins counteract antibiotic action by capturing antibiotics in the extracellular space. We also demonstrated that fat-soluble vitamins prevent antibiotic capture by binding bacterial lipocalin with higher affinity than antibiotics. Therefore, bacterial lipocalins contribute to antimicrobial resistance by capturing diverse antibiotics in the extracellular space at the site of infection, which can be counteracted by known vitamins.IMPORTANCE Current research on antibiotic action and resistance focuses on targeting essential functions within bacterial cells. We discovered a previously unrecognized mode of general bacterial antibiotic resistance operating in the extracellular space, which depends on bacterial protein molecules called lipocalins. These molecules are highly conserved in most bacteria and have the ability to capture different classes of antibiotics outside bacterial cells. We also discovered that liposoluble vitamins, such as vitamin E, overcome in vitro and in vivo antibiotic resistance mediated by bacterial lipocalins, providing an unexpected new alternative to combat resistance by using this vitamin or its derivatives as antibiotic adjuvants.

  16. Increase in Antibiotic-Resistant Gram-Negative Bacterial Infections in Febrile Neutropenic Children

    PubMed Central

    2016-01-01

    Background The incidence of bacteremia caused by Gram-negative bacteria has increased recently in febrile neutropenic patients with the increase of antibiotic-resistant Gram-negative bacterial infections. This study aimed to identify the distribution of causative bacteria and the proportion of antibiotic-resistant bacteria in bacteremia diagnosed in febrile neutropenic children. Materials and Methods The medical records of febrile neutropenic children diagnosed with bacteremia between 2010 and 2014 were retrospectively reviewed. The causative bacteria and proportion of antibiotic-resistant bacteria were investigated and compared yearly during the study period. The clinical impact of antibiotic-resistant bacterial infections was also determined. Results A total of 336 bacteremia episodes were identified. During the entire study period, 181 (53.9%) and 155 (46.1%) episodes were caused by Gram-negative and Gram-positive bacteria, respectively. Viridans streptococci (25.9%), Klebsiella spp. (16.7%), and Escherichia coli (16.4%) were the most frequent causative bacteria. The overall distribution of causative bacteria was not significantly different annually. Antibiotic-resistant bacteria were identified in 85 (25.3%) episodes, and the proportion of antibiotic-resistant bacteria was not significantly different annually. Extended-spectrum β-lactamase-producing E. coli and Klebsiella spp. were most common among antibiotic-resistant Gram-negative bacteria, and they accounted for 30.6% (n = 34) of the identified E. coli and K. pneumoniae. Methicillin-resistant coagulase-negative staphylococci were most common among antibiotic-resistant Gram-positive bacteria, and it accounted for 88.5% (n = 23) of the identified coagulase-negative staphylococci. Antibiotic-resistant bacterial infections, especially antibiotic-resistant Gram-negative bacterial infections, caused significantly higher mortality due to bacteremia compared with non-antibiotic-resistant bacterial infections (P <0

  17. Antibiotic Capture by Bacterial Lipocalins Uncovers an Extracellular Mechanism of Intrinsic Antibiotic Resistance

    PubMed Central

    El-Halfawy, Omar M.; Klett, Javier; Ingram, Rebecca J.; Loutet, Slade A.; Murphy, Michael E. P.; Martín-Santamaría, Sonsoles

    2017-01-01

    ABSTRACT The potential for microbes to overcome antibiotics of different classes before they reach bacterial cells is largely unexplored. Here we show that a soluble bacterial lipocalin produced by Burkholderia cenocepacia upon exposure to sublethal antibiotic concentrations increases resistance to diverse antibiotics in vitro and in vivo. These phenotypes were recapitulated by heterologous expression in B. cenocepacia of lipocalin genes from Pseudomonas aeruginosa, Mycobacterium tuberculosis, and methicillin-resistant Staphylococcus aureus. Purified lipocalin bound different classes of bactericidal antibiotics and contributed to bacterial survival in vivo. Experimental and X-ray crystal structure-guided computational studies revealed that lipocalins counteract antibiotic action by capturing antibiotics in the extracellular space. We also demonstrated that fat-soluble vitamins prevent antibiotic capture by binding bacterial lipocalin with higher affinity than antibiotics. Therefore, bacterial lipocalins contribute to antimicrobial resistance by capturing diverse antibiotics in the extracellular space at the site of infection, which can be counteracted by known vitamins. PMID:28292982

  18. Suppression of bacterial blight on mustard greens with host plant resistance and Acibenzolar-S-Methyl

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial blight, caused by Pseudomonas cannabina pv. alisalensis, attacks the leaves of most brassica vegetables, including mustard greens (Brassica juncea). ‘Carolina Broadleaf,’ a new mustard cultivar, is resistant to bacterial blight. Acibenzolar-S-methyl (trade name Actigard) has been used to m...

  19. Dominant gene for common bean resistance to common bacterial blight caused by Xanthomonas axonopodis pv. phaseoli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The common bacterial blight pathogen [Xanthomonas axonopodis pv. phaseoli (Xap)] is a limiting factor for common bean (Phaseolus vulgaris L.) production worldwide and resistance to the pathogen in most commercial cultivars is inadequate. Variability in virulence of the bacterial pathogen has been ob...

  20. Experimental Induction of Bacterial Resistance to the Antimicrobial Peptide Tachyplesin I and Investigation of the Resistance Mechanisms

    PubMed Central

    Hu, Jianye; Ke, Fei

    2016-01-01

    Tachyplesin I is a 17-amino-acid cationic antimicrobial peptide (AMP) with a typical cyclic antiparallel β-sheet structure that is a promising therapeutic for infections, tumors, and viruses. To date, no bacterial resistance to tachyplesin I has been reported. To explore the safety of tachyplesin I as an antibacterial drug for wide clinical application, we experimentally induced bacterial resistance to tachyplesin I by using two selection procedures and studied the preliminary resistance mechanisms. Aeromonas hydrophila XS91-4-1, Pseudomonas aeruginosa CGMCC1.2620, and Escherichia coli ATCC 25922 and F41 showed resistance to tachyplesin I under long-term selection pressure with continuously increasing concentrations of tachyplesin I. In addition, P. aeruginosa and E. coli exhibited resistance to tachyplesin I under UV mutagenesis selection conditions. Cell growth and colony morphology were slightly different between control strains and strains with induced resistance. Cross-resistance to tachyplesin I and antimicrobial agents (cefoperazone and amikacin) or other AMPs (pexiganan, tachyplesin III, and polyphemusin I) was observed in some resistant mutants. Previous studies showed that extracellular protease-mediated degradation of AMPs induced bacterial resistance to AMPs. Our results indicated that the resistance mechanism of P. aeruginosa was not entirely dependent on extracellular proteolytic degradation of tachyplesin I; however, tachyplesin I could induce increased proteolytic activity in P. aeruginosa. Most importantly, our findings raise serious concerns about the long-term risks associated with the development and clinical use of tachyplesin I. PMID:27480861

  1. Experimental Induction of Bacterial Resistance to the Antimicrobial Peptide Tachyplesin I and Investigation of the Resistance Mechanisms.

    PubMed

    Hong, Jun; Hu, Jianye; Ke, Fei

    2016-10-01

    Tachyplesin I is a 17-amino-acid cationic antimicrobial peptide (AMP) with a typical cyclic antiparallel β-sheet structure that is a promising therapeutic for infections, tumors, and viruses. To date, no bacterial resistance to tachyplesin I has been reported. To explore the safety of tachyplesin I as an antibacterial drug for wide clinical application, we experimentally induced bacterial resistance to tachyplesin I by using two selection procedures and studied the preliminary resistance mechanisms. Aeromonas hydrophila XS91-4-1, Pseudomonas aeruginosa CGMCC1.2620, and Escherichia coli ATCC 25922 and F41 showed resistance to tachyplesin I under long-term selection pressure with continuously increasing concentrations of tachyplesin I. In addition, P. aeruginosa and E. coli exhibited resistance to tachyplesin I under UV mutagenesis selection conditions. Cell growth and colony morphology were slightly different between control strains and strains with induced resistance. Cross-resistance to tachyplesin I and antimicrobial agents (cefoperazone and amikacin) or other AMPs (pexiganan, tachyplesin III, and polyphemusin I) was observed in some resistant mutants. Previous studies showed that extracellular protease-mediated degradation of AMPs induced bacterial resistance to AMPs. Our results indicated that the resistance mechanism of P. aeruginosa was not entirely dependent on extracellular proteolytic degradation of tachyplesin I; however, tachyplesin I could induce increased proteolytic activity in P. aeruginosa Most importantly, our findings raise serious concerns about the long-term risks associated with the development and clinical use of tachyplesin I.

  2. Identification of New Drug Targets in Multi-Drug Resistant Bacterial Infections

    DTIC Science & Technology

    2014-10-01

    Identification of New Drug Targets in Multi-Drug Resistant Bacterial Infections PRINCIPAL INVESTIGATOR: Andrew M. Gulick, PhD...Identification of New Drug Targets in Multi-Drug Resistant Bacterial Infections 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-11-2-0218 5c... infections . Recently, community-acquired infections , infections in wounded U.S. service members, and infections in residents of long-term care facilities

  3. Evolution of antibiotic resistance is linked to any genetic mechanism affecting bacterial duration of carriage

    PubMed Central

    Lehtinen, Sonja; Blanquart, François; Croucher, Nicholas J.; Turner, Paul; Lipsitch, Marc; Fraser, Christophe

    2017-01-01

    Understanding how changes in antibiotic consumption affect the prevalence of antibiotic resistance in bacterial pathogens is important for public health. In a number of bacterial species, including Streptococcus pneumoniae, the prevalence of resistance has remained relatively stable despite prolonged selection pressure from antibiotics. The evolutionary processes allowing the robust coexistence of antibiotic sensitive and resistant strains are not fully understood. While allelic diversity can be maintained at a locus by direct balancing selection, there is no evidence for such selection acting in the case of resistance. In this work, we propose a mechanism for maintaining coexistence at the resistance locus: linkage to a second locus that is under balancing selection and that modulates the fitness effect of resistance. We show that duration of carriage plays such a role, with long duration of carriage increasing the fitness advantage gained from resistance. We therefore predict that resistance will be more common in strains with a long duration of carriage and that mechanisms maintaining diversity in duration of carriage will also maintain diversity in antibiotic resistance. We test these predictions in S. pneumoniae and find that the duration of carriage of a serotype is indeed positively correlated with the prevalence of resistance in that serotype. These findings suggest heterogeneity in duration of carriage is a partial explanation for the coexistence of sensitive and resistant strains and that factors determining bacterial duration of carriage will also affect the prevalence of resistance. PMID:28096340

  4. Evolution of antibiotic resistance is linked to any genetic mechanism affecting bacterial duration of carriage.

    PubMed

    Lehtinen, Sonja; Blanquart, François; Croucher, Nicholas J; Turner, Paul; Lipsitch, Marc; Fraser, Christophe

    2017-01-31

    Understanding how changes in antibiotic consumption affect the prevalence of antibiotic resistance in bacterial pathogens is important for public health. In a number of bacterial species, including Streptococcus pneumoniae, the prevalence of resistance has remained relatively stable despite prolonged selection pressure from antibiotics. The evolutionary processes allowing the robust coexistence of antibiotic sensitive and resistant strains are not fully understood. While allelic diversity can be maintained at a locus by direct balancing selection, there is no evidence for such selection acting in the case of resistance. In this work, we propose a mechanism for maintaining coexistence at the resistance locus: linkage to a second locus that is under balancing selection and that modulates the fitness effect of resistance. We show that duration of carriage plays such a role, with long duration of carriage increasing the fitness advantage gained from resistance. We therefore predict that resistance will be more common in strains with a long duration of carriage and that mechanisms maintaining diversity in duration of carriage will also maintain diversity in antibiotic resistance. We test these predictions in S. pneumoniae and find that the duration of carriage of a serotype is indeed positively correlated with the prevalence of resistance in that serotype. These findings suggest heterogeneity in duration of carriage is a partial explanation for the coexistence of sensitive and resistant strains and that factors determining bacterial duration of carriage will also affect the prevalence of resistance.

  5. Pyramiding transgenic resistance in elite indica rice cultivars against the sheath blight and bacterial blight.

    PubMed

    Maruthasalam, S; Kalpana, K; Kumar, K K; Loganathan, M; Poovannan, K; Raja, J A J; Kokiladevi, E; Samiyappan, R; Sudhakar, D; Balasubramanian, P

    2007-06-01

    Elite indica rice cultivars were cotransformed with genes expressing a rice chitinase (chi11) and a thaumatin-like protein (tlp) conferring resistance to fungal pathogens and a serine-threonine kinase (Xa21) conferring bacterial blight resistance, through particle bombardment, with a view to pyramiding sheath blight and bacterial blight resistance. Molecular analyses of putative transgenic lines by polymerase chain reaction, Southern Blot hybridization, and Western Blotting revealed stable integration and expression of the transgenes in a few independent transgenic lines. Progeny analyses showed the stable inheritance of transgenes to their progeny. Coexpression of chitinase and thaumatin-like protein in the progenies of a transgenic Pusa Basmati1 line revealed an enhanced resistance to the sheath blight pathogen, Rhizoctonia solani, as compared to that in the lines expressing the individual genes. A transgenic Pusa Basmati1 line pyramided with chi11, tlp, and Xa21 showed an enhanced resistance to both sheath blight and bacterial blight.

  6. Resistance of Aerosolized Bacterial Viruses to Four Germicidal Products

    PubMed Central

    Turgeon, Nathalie; Michel, Kevin; Ha, Thi-Lan; Robine, Enric; Moineau, Sylvain; Duchaine, Caroline

    2016-01-01

    Viral diseases can spread through a variety of routes including aerosols. Yet, limited data are available on the efficacy of aerosolized chemicals to reduce viral loads in the air. Bacteriophages (phages) are often used as surrogates for hazardous viruses in aerosol studies because they are inexpensive, easy to handle, and safe for laboratory workers. Moreover, several of these bacterial viruses display physical characteristics similar to pathogenic human and animal viruses, like morphological size, type of nucleic acids, capsid morphology, and the presence of an envelope. In this study, the efficacy of four chemicals was evaluated on four airborne phages at two different relative humidity levels. Non-tailed bacteriophages MS2 (single-stranded RNA), ϕ6 (double-stranded RNA, enveloped), PR772 (double-stranded DNA), and ϕX174 (single-stranded DNA) were first aerosolized in a 55L rotative environmental chamber at 19°C with 25% and 50% relative humidity. Then, hydrogen peroxide, Eugenol (phenylpropene used in commercial perfumes and flavorings), Mist® (automobile disinfectant containing Triethylene glycol), and Pledge® (multisurface disinfectant containing Isopropanol, n-Alkyl Dimethyl Benzyl Amonium Chlorides, and n-Alkyl Dimethyl Ethylbenzyl Ammonium Chloride) were nebulized with the phages using a separate nebulizer. Aerosols were maintained in suspension during 10 minutes, 1 hour, and 2 hours. Viral aerosols were sampled using an SKC BioSampler and samples were analyzed using qPCR and plaque assays. The resistance levels of the four phages varied depending on the relative humidity (RH) and germicidal products tested. Phage MS2 was the most stable airborne virus under the environmental conditions tested while phage PR772 was the least stable. Pledge® and Eugenol reduced the infectivity of all airborne phages tested. At 25% RH, Pledge® and Eugenol were more effective at reducing infectivity of RNA phages ϕ6 and MS2. At 50% RH, Pledge® was the most effective

  7. Effect of Vibration on Bacterial Growth and Antibiotic Resistance

    NASA Technical Reports Server (NTRS)

    Juergensmeyer, Elizabeth A.; Juergensmeyer, Margaret A.

    2004-01-01

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

  8. Multidrug Efflux Pumps at the Crossroad between Antibiotic Resistance and Bacterial Virulence.

    PubMed

    Alcalde-Rico, Manuel; Hernando-Amado, Sara; Blanco, Paula; Martínez, José L

    2016-01-01

    Multidrug efflux pumps can be involved in bacterial resistance to antibiotics at different levels. Some efflux pumps are constitutively expressed at low levels and contribute to intrinsic resistance. In addition, their overexpression may allow higher levels of resistance. This overexpression can be transient, in the presence of an effector (phenotypic resistance), or constitutive when mutants in the regulatory elements of the expression of efflux pumps are selected (acquired resistance). Efflux pumps are present in all cells, from human to bacteria and are highly conserved, which indicates that they are ancient elements in the evolution of different organisms. Consequently, it has been suggested that, besides antibiotic resistance, bacterial multidrug efflux pumps would likely contribute to other relevant processes of the microbial physiology. In the current article, we discuss some specific examples of the role that efflux pumps may have in the bacterial virulence of animals' and plants' pathogens, including the processes of intercellular communication. Based in these evidences, we propose that efflux pumps are at the crossroad between resistance and virulence of bacterial pathogens. Consequently, the comprehensive study of multidrug efflux pumps requires addressing these functions, which are of relevance for the bacterial-host interactions during infection.

  9. Genetic engineering for increasing fungal and bacterial disease resistance in crop plants.

    PubMed

    Wally, Owen; Punja, Zamir K

    2010-01-01

    We review the current and future potential of genetic engineering strategies used to make fungal and bacterial pathogen-resistant GM crops, illustrating different examples of the technologies and the potential benefits and short-falls of the strategies. There are well- established procedures for the production of transgenic plants with resistance towards these pathogens and considerable progress has been made using a range of new methodologies. There are no current commercially available transgenic plant species with increased resistance towards fungal and bacterial pathogens; only plants with increased resistance towards viruses are available. With an improved understanding of plant signaling pathways in response to a range of other pathogens, such as fungi, additional candidate genes for achieving resistance are being investigated. The potential for engineering plants for resistance against individual devastating diseases or for plants with resistance towards multiple pathogens is discussed in detail.

  10. Bacterial resistance and impetigo treatment trends: a review.

    PubMed

    Bangert, Scott; Levy, Moise; Hebert, Adelaide A

    2012-01-01

    Impetigo is a common cutaneous infection that is especially prevalent in children. The prevalence of colonization and infection with resistant strains is continually increasing, forcing clinicians to reevaluate treatment strategies. Newer topical agents are effective in treating infections with resistant strains and may help minimize resistance and adverse effects from systemic agents. Use of topical disinfectants to decrease colonization is an important adjunctive measure. Physicians should be aware of local resistance patterns in impetigo to help guide therapy.

  11. Pilot Screening to Determine Antimicrobial Synergies in a Multidrug-Resistant Bacterial Strain Library

    PubMed Central

    Kim, Si-Hyun; Park, Chulmin; Chun, Hye-Sun; Choi, Jae-Ki; Lee, Hyo-Jin; Cho, Sung-Yeon; Park, Sun Hee; Choi, Su-Mi; Choi, Jung-Hyun; Yoo, Jin-Hong

    2016-01-01

    With the rise in multidrug-resistant (MDR) bacterial infections, there has been increasing interest in combinations of ≥2 antimicrobial agents with synergistic effects. We established an MDR bacterial strain library to screen for in vitro antimicrobial synergy by using a broth microdilution checkerboard method and high-throughput luciferase-based bacterial cell viability assay. In total, 39 MDR bacterial strains, including 23 carbapenem-resistant gram-negative bacteria, 9 vancomycin-intermediate Staphylococcus aureus, and 7 vancomycin-resistant Enterococcus faecalis, were used to screen for potential antimicrobial synergies. Synergies were more frequently identified with combinations of imipenem plus trimethoprim–sulfamethoxazole for carbapenem-resistant Acinetobacter baumannii in the library. To verify this finding, we tested 34 A. baumannii clinical isolates resistant to both imipenem and trimethoprim–sulfamethoxazole by the checkerboard method. The imipenem plus trimethoprim–sulfamethoxazole combination showed synergy in the treatment of 21 (62%) of the clinical isolates. The results indicate that pilot screening for antimicrobial synergy in the MDR bacterial strain library could be valuable in the selection of combination therapeutic regimens to treat MDR bacterial infections. Further studies are warranted to determine whether this screening system can be useful to screen for the combined effects of conventional antimicrobials and new-generation antimicrobials or nonantimicrobials. PMID:26974861

  12. [Advances in molecular mechanisms of bacterial resistance caused by stress-induced transfer of resistance genes--a review].

    PubMed

    Sun, Dongchang; Wang, Bing; Zhu, Lihong

    2013-07-04

    The transfer of resistance gene is one of the most important causes of bacterial resistance. Recent studies reveal that stresses induce the transfer of antibiotic resistance gene through multiple mechanisms. DNA damage stresses trigger bacterial SOS response and induce the transfer of resistance gene mediated by conjugative DNA. Antibiotic stresses induce natural bacterial competence for transformation in some bacteria which lack the SOS system. In addition, our latest studies show that the general stress response regulator RpoS regulates a novel type of resistance gene transfer which is mediated by double-stranded plasmid DNA and occurs exclusively on the solid surface. In this review, we summarized recent advances in SOS dependent and independent stress-induced DNA transfer which is mediated by conjugation and transformation respectively, and the transfer of double-stranded plasmid DNA on the solid surface which is regulated by RpoS. We propose that future work should address how stresses activate the key regulators and how these regulators control the expression of gene transfer related genes. Answers to the above questions would pave the way for searching for candidate targets for controlling bacterial resistance resulted from the transfer of antibiotic genes.

  13. Effect of Lipid Materials on Heat Resistance of Bacterial Spores

    PubMed Central

    Molin, N.; Snygg, B. G.

    1967-01-01

    The apparent heat resistance of spores of Bacillus megaterium, B. subtilis, B. cereus, B. stearothermophilus, and Clostridium botulinum type E in lipids was investigated and compared with the resistance of the spores in phosphate buffer solution. The most pronounced increase in heat resistance was noted for B. subtilis and C. botulinum type E, the increase varying with the type of lipid used. A high water content of the lipids used as heating menstruum lowered the heat resistance of the spores. Possible explanations for the high heat resistance of spores in lipids are discussed. PMID:16349757

  14. Response to selection for bacterial cold water disease resistance in rainbow trout

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous studies indicate that resistance to experimental bacterial cold water disease (BCWD) challenge is heritable and thus may be improved through selective breeding. Our objective was to estimate response after one generation of genetic selection for resistance to BCWD in a pedigreed population ...

  15. Phenotypic resistance and the dynamics of bacterial escape from phage control.

    PubMed

    Bull, James J; Vegge, Christina Skovgaard; Schmerer, Matthew; Chaudhry, Waqas Nasir; Levin, Bruce R

    2014-01-01

    The canonical view of phage - bacterial interactions in dense, liquid cultures is that the phage will eliminate most of the sensitive cells; genetic resistance will then ascend to restore high bacterial densities. Yet there are various mechanisms by which bacteria may remain sensitive to phages but still attain high densities in their presence - because bacteria enter a transient state of reduced adsorption. Importantly, these mechanisms may be cryptic and inapparent prior to the addition of phage yet result in a rapid rebound of bacterial density after phage are introduced. We describe mathematical models of these processes and suggest how different types of this 'phenotypic' resistance may be elucidated. We offer preliminary in vitro studies of a previously characterized E. coli model system and Campylobacter jejuni illustrating apparent phenotypic resistance. As phenotypic resistance may be specific to the receptors used by phages, awareness of its mechanisms may identify ways of improving the choice of phages for therapy. Phenotypic resistance can also explain several enigmas in the ecology of phage-bacterial dynamics. Phenotypic resistance does not preclude the evolution of genetic resistance and may often be an intermediate step to genetic resistance.

  16. New source of bacterial soft rot resistance in wild potato (Solanum chacoense) tubers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial soft rot caused by Pectobacterium and Dickeya species can cause major losses to the potato (Solanum tuberosum L.) industry, mostly due to tuber rot in storage. There are few germplasm resources for soft rot resistance breeding. Here, we introduce a resistant diploid wild potato relative, M...

  17. Antimicrobial resistance in bacterial isolates from a delhi hospital: one year outcomes.

    PubMed

    Jain, Sanjay; Sharma, Yukti; Arora, Vivek; Deka, Lopamudra; Singh, Sompal

    2013-01-01

    Antimicrobial resistance and hospital acquired infections have become an important public health issue. Data on pathogen and antibiotic resistance is important for physicians, microbiologists and infection control officials but limited information on antibiotic resistance prevents pathogen specific therapy and propels antibiotic misuse. A retrospective review of bacterial isolation and antimicrobial susceptibility profiles in the in- and outpatients of a Delhi hospital between January 2009-December 2009 was performed. A total of 1772 pathogens causing bacterial infections were recorded during the study period January 2009-December 2009. The most frequently encountered bacterial pathogens were Escherichia coli (40.51%), Klebsiella spp. (14.84%) and Staphylococcus aureus (13.99%). We encountered high resistance to ciprofloxacin in Enterobactereaceae family, i.e., 32.5%. Aminoglycosides, once considered optimum for broad spectrum coverage of pathogens for almost all systemic infections, are now showing high rate of resistance as was noted in Acinetobacter sp. (57.14%) and Pseudomonas aeruginosa (69.2%). Antibiotic susceptibility results show a higher level of resistance to cotrimoxazole, cephalosporins and ciprofloxacin which are easily available, orally administered and cheaper and thus are considered a better option for the patients. This study provides insight into the problem of resistance in bacterial pathogens in Delhi. Our results demonstrated that, in general, isolates have high rates of resistance to antibiotics commonly used in developing countries. Guidelines for surveillance and prevention of nosocomial infections must be implemented in order to reduce the rate of hospital acquired infections.

  18. Pattern of Pediatric Bacterial Infection and Antibiotic Resistance in New Delhi.

    PubMed

    Roy, Manas Pratim; Gaind, Rajni; Aggarwal, Kailash Chander; Chellani, Harish Kumar; Biswal, Indu

    2017-02-15

    The retrospective study analyzed 1025 bacterial isolates from blood cultures collected from pediatric patients admitted in a tertiary-care hospital in New Delhi to find out drug sensitivity patterns. Staphylococcus was isolated from approximate 70% of the cultures, with 63.7% of them being methicillin-resistant. Meropenem resistance among acinetobacter was 38.6%.

  19. Defensive remodeling: How bacterial surface properties and biofilm formation promote resistance to antimicrobial peptides.

    PubMed

    Nuri, Reut; Shprung, Tal; Shai, Yechiel

    2015-11-01

    Multidrug resistance bacteria are a major concern worldwide. These pathogens cannot be treated with conventional antibiotics and thus alternative therapeutic agents are needed. Antimicrobial peptides (AMPs) are considered to be good candidates for this purpose. Most AMPs are short and positively charged amphipathic peptides, which are found in all known forms of life. AMPs are known to kill bacteria by binding to the negatively charged bacterial surface, and in most cases cause membrane disruption. Resistance toward AMPs can be developed, by modification of bacterial surface molecules, secretion of protective material and up-regulation or elimination of specific proteins. Because of the general mechanisms of attachment and action of AMPs, bacterial resistance to AMPs often involves biophysical and biochemical changes such as surface rigidity, cell wall thickness, surface charge, as well as membrane and cell wall modification. Here we focus on the biophysical, surface and surrounding changes that bacteria undergo in acquiring resistance to AMPs. In addition we discuss the question of whether bacterial resistance to administered AMPs might compromise our innate immunity to endogenous AMPs. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.

  20. Effects of antibiotic resistance alleles on bacterial evolutionary responses to viral parasites.

    PubMed

    Arias-Sánchez, Flor I; Hall, Alex R

    2016-05-01

    Antibiotic resistance has wide-ranging effects on bacterial phenotypes and evolution. However, the influence of antibiotic resistance on bacterial responses to parasitic viruses remains unclear, despite the ubiquity of such viruses in nature and current interest in therapeutic applications. We experimentally investigated this by exposing various Escherichia coli genotypes, including eight antibiotic-resistant genotypes and a mutator, to different viruses (lytic bacteriophages). Across 960 populations, we measured changes in population density and sensitivity to viruses, and tested whether variation among bacterial genotypes was explained by their relative growth in the absence of parasites, or mutation rate towards phage resistance measured by fluctuation tests for each phage. We found that antibiotic resistance had relatively weak effects on adaptation to phages, although some antibiotic-resistance alleles impeded the evolution of resistance to phages via growth costs. By contrast, a mutator allele, often found in antibiotic-resistant lineages in pathogenic populations, had a relatively large positive effect on phage-resistance evolution and population density under parasitism. This suggests costs of antibiotic resistance may modify the outcome of phage therapy against pathogenic populations previously exposed to antibiotics, but the effects of any co-occurring mutator alleles are likely to be stronger.

  1. Evolution of resistance to a last-resort antibiotic in Staphyloccocus aureus via bacterial competition

    PubMed Central

    Koch, Gudrun; Yepes, Ana; Förstner, Konrad U.; Wermser, Charlotte; Stengel, Stephanie T.; Modamio, Jennifer; Ohlsen, Knut; Foster, Kevin R.; Lopez, Daniel

    2014-01-01

    Summary Antibiotic resistance is a key medical concern, with antibiotic use likely being an important cause. However, here we describe an alternative route to clinically-relevant antibiotic resistance that occurs solely due to competitive interactions between bacterial cells. We consistently observe that isolates of Methicillin-resistant Staphylococcus aureus diversify spontaneously into two distinct, sequentially arising strains. The first evolved strain outgrows the parent strain via secretion of surfactants and a toxic bacteriocin. The second is resistant to the bacteriocin. Importantly, this second strain is also resistant to intermediate levels of vancomycin. This so-called VISA (vancomycin-intermediate S. aureus) phenotype is seen in many hard-to-treat clinical isolates. This strain diversification also occurs during in vivo infection in a mouse model, consistent with the fact that both coevolved phenotypes resemble strains commonly found in clinic. Our study shows how competition between coevolving bacterial strains can generate antibiotic resistance and recapitulate key clinical phenotypes. PMID:25171407

  2. Bacterial flora and antimicrobial resistance in raw frozen cultured seafood imported to Denmark.

    PubMed

    Noor Uddin, Gazi M; Larsen, Marianne Halberg; Guardabassi, Luca; Dalsgaard, Anders

    2013-03-01

    Intensified aquaculture includes the use of antimicrobials for disease control. In contrast to the situation in livestock, Escherichia coli and enterococci are not part of the normal gastrointestinal flora of fish and shrimp and therefore not suitable indicators of antimicrobial resistance in seafood. In this study, the diversity and phenotypic characteristics of the bacterial flora in raw frozen cultured and wild-caught shrimp and fish were evaluated to identify potential indicators of antimicrobial resistance. The bacterial flora cultured on various agar media at different temperatures yielded total viable counts of 4.0 × 10(4) to 3.0 × 10(5) CFU g(-1). Bacterial diversity was indicated by 16S rRNA sequence analysis of 84 isolates representing different colony types; 24 genera and 51 species were identified. Pseudomonas spp. (23% of isolates), Psychrobacter spp. (17%), Serratia spp. (13%), Exiguobacterium spp. (7%), Staphylococcus spp. (6%), and Micrococcus spp. (6%) dominated. Disk susceptibility testing of 39 bacterial isolates to 11 antimicrobials revealed resistance to ampicillin, amoxicillin-clavulanic acid, erythromycin, and third generation cephalosporins. Resistance to third generation cephalosporins was found in Pseudomonas, a genus naturally resistant to most β-lactam antibiotics, and in Staphylococcus hominis. Half of the isolates were susceptible to all antimicrobials tested. Results indicate that identification of a single bacterial resistance indicator naturally present in seafood at point of harvest is unlikely. The bacterial flora found likely represents a processing rather than a raw fish flora because of repeated exposure of raw material to water during processing. Methods and appropriate indicators, such as quantitative PCR of resistance genes, are needed to determine how antimicrobials used in aquaculture affect resistance of bacteria in retailed products.

  3. 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.

  4. Resistance trends among clinical isolates in China reported from CHINET surveillance of bacterial resistance, 2005-2014.

    PubMed

    Hu, F-P; Guo, Y; Zhu, D-M; Wang, F; Jiang, X-F; Xu, Y-C; Zhang, X-J; Zhang, C-X; Ji, P; Xie, Y; Kang, M; Wang, C-Q; Wang, A-M; Xu, Y-H; Shen, J-L; Sun, Z-Y; Chen, Z-J; Ni, Y-X; Sun, J-Y; Chu, Y-Z; Tian, S-F; Hu, Z-D; Li, J; Yu, Y-S; Lin, J; Shan, B; Du, Y; Han, Y; Guo, S; Wei, L-H; Wu, L; Zhang, H; Kong, J; Hu, Y-J; Ai, X-M; Zhuo, C; Su, D-H; Yang, Q; Jia, B; Huang, W

    2016-03-01

    With the aim of gathering temporal trends on bacterial epidemiology and resistance from multiple laboratories in China, the CHINET surveillance system was organized in 2005. Antimicrobial susceptibility testing was carried out according to a unified protocol using the Kirby-Bauer method or automated systems. Results were analyzed according to Clinical and Laboratory Standards Institute (CLSI) 2014 definitions. Between 2005 and 2014, the number of bacterial isolates ranged between 22,774 and 84,572 annually. Rates of extended-spectrum β-lactamase production among Escherichia coli isolates were stable, between 51.7 and 55.8%. Resistance of E. coli and Klebsiella pneumoniae to amikacin, ciprofloxacin, piperacillin/tazobactam and cefoperazone/sulbactam decreased with time. Carbapenem resistance among K. pneumoniae isolates increased from 2.4 to 13.4%. Resistance of Pseudomonas aeruginosa strains against all of antimicrobial agents tested including imipenem and meropenem decreased with time. On the contrary, resistance of Acinetobacter baumannii strains to carbapenems increased from 31 to 66.7%. A marked decrease of methicillin resistance from 69% in 2005 to 44.6% in 2014 was observed for Staphylococcus aureus. Carbapenem resistance rates in K. pneumoniae and A. baumannii in China are high. Our results indicate the importance of bacterial surveillance studies.

  5. Immunological multimetal deposition for rapid visualization of sweat fingerprints.

    PubMed

    He, Yayun; Xu, Linru; Zhu, Yu; Wei, Qianhui; Zhang, Meiqin; Su, Bin

    2014-11-10

    A simple method termed immunological multimetal deposition (iMMD) was developed for rapid visualization of sweat fingerprints with bare eyes, by combining the conventional MMD with the immunoassay technique. In this approach, antibody-conjugated gold nanoparticles (AuNPs) were used to specifically interact with the corresponding antigens in the fingerprint residue. The AuNPs serve as the nucleation sites for autometallographic deposition of silver particles from the silver staining solution, generating a dark ridge pattern for visual detection. Using fingerprints inked with human immunoglobulin G (hIgG), we obtained the optimal formulation of iMMD, which was then successfully applied to visualize sweat fingerprints through the detection of two secreted polypeptides, epidermal growth factor and lysozyme. In comparison with the conventional MMD, iMMD is faster and can provide additional information than just identification. Moreover, iMMD is facile and does not need expensive instruments.

  6. Socioeconomic and behavioral factors leading to acquired bacterial resistance to antibiotics in developing countries.

    PubMed Central

    Okeke, I. N.; Lamikanra, A.; Edelman, R.

    1999-01-01

    In developing countries, acquired bacterial resistance to antimicrobial agents is common in isolates from healthy persons and from persons with community-acquired infections. Complex socioeconomic and behavioral factors associated with antibiotic resistance, particularly regarding diarrheal and respiratory pathogens, in developing tropical countries, include misuse of antibiotics by health professionals, unskilled practitioners, and laypersons; poor drug quality; unhygienic conditions accounting for spread of resistant bacteria; and inadequate surveillance. PMID:10081668

  7. Multidrug Efflux Pumps at the Crossroad between Antibiotic Resistance and Bacterial Virulence

    PubMed Central

    Alcalde-Rico, Manuel; Hernando-Amado, Sara; Blanco, Paula; Martínez, José L.

    2016-01-01

    Multidrug efflux pumps can be involved in bacterial resistance to antibiotics at different levels. Some efflux pumps are constitutively expressed at low levels and contribute to intrinsic resistance. In addition, their overexpression may allow higher levels of resistance. This overexpression can be transient, in the presence of an effector (phenotypic resistance), or constitutive when mutants in the regulatory elements of the expression of efflux pumps are selected (acquired resistance). Efflux pumps are present in all cells, from human to bacteria and are highly conserved, which indicates that they are ancient elements in the evolution of different organisms. Consequently, it has been suggested that, besides antibiotic resistance, bacterial multidrug efflux pumps would likely contribute to other relevant processes of the microbial physiology. In the current article, we discuss some specific examples of the role that efflux pumps may have in the bacterial virulence of animals’ and plants’ pathogens, including the processes of intercellular communication. Based in these evidences, we propose that efflux pumps are at the crossroad between resistance and virulence of bacterial pathogens. Consequently, the comprehensive study of multidrug efflux pumps requires addressing these functions, which are of relevance for the bacterial–host interactions during infection. PMID:27708632

  8. Multidrug resistance pattern of bacterial agents isolated from patient with chronic sinusitis

    PubMed Central

    Rezai, Mohammad Sadegh; Pourmousa, Rostam; Dadashzadeh, Roksana; Ahangarkani, Fatemeh

    2016-01-01

    Background: Treatment of chronic sinusitis is complicated due to increase of antibiotic-resistant bacteria. The aim of this study was to determine the multidrug resistance (MDR) pattern of the bacteria causing chronic sinusitis in north of Iran. Methods: This cross-sectional study was carried out on patients with chronic sinusitis. Bacterial susceptibility to antimicrobial agents was determined according to the CLSI 2013 standards. Double-disk synergy (DDS) test was performed for the detection of extended-spectrum beta-lactamase (ESBL) producing bacteria; also methicillin-resistant Staphylococcus (MRSA) strains were identified by MRSA screen agar. The MDR isolates were defined as resistant to 3 or more antibiotics. Data were analyzed using SPSS 17 software. Descriptive statistics was used to describe the features of the data in this study. Results: The rate of ESBL-producing bacteria was 28.75-37.03% among enterobacteriaceae and the rate of MRSA was 42.75%-60% among Staphylococcus strains. The most detectable rate of the MDR bacterial isolates was Gram-negative bacteria 39 (76.47%) and Enterobacter spp. 19(70.37%) was the most multidrug resistant isolate among Gram negative bacteria. Also 36 (73.46%) of the gram positive bacterial isolated were multidrug resistance and Staphylococcus aureus 9(90%) was the most MDR among Gram positive bacteria. Conclusion: Antimicrobial resistance is increasing in chronic bacterial sinusitis. The emergence of MRSA and ESBL bacteria causing chronic sinusitis is increasing. PMID:27386063

  9. 1997 Performance Testing of Multi-Metal Continuous Emissions Monitors

    SciTech Connect

    Sky +, Inc.

    1998-09-01

    Five prototype and two commercially available multi-metals continuous emissions monitors (CEMs) were tested in September 1997 at the Rotary Kiln Incinerator Simulator facility at the EPA National Risk Management Research Laboratory, Research Triangle Park, North Carolina. The seven CEMs were tested side by side in a long section of duct following the secondary combustion chamber of the RKIS. Two different concentrations of six toxic metals were introduced into the incinerator-approximately 15 and 75 µg/dscm of arsenic, beryllium, cadmium, chromium, lead, and mercury (We also tested for antimony but we are not reporting on it here because EPA recently dropped antimony from the list of metals addressed by the draft MACT rule). These concentrations were chosen to be close to emission standards in the draft MACT rule and the estimated Method Detection Limit (MDL) required of a CEM for regulatory compliance purposes. Results from this test show that no CEMs currently meet the performance specifications in the EPA draft MACT rule for hazardous waste incinerators. Only one of the CEMs tested was able to measure all six metals at the concentrations tested. Even so, the relative accuracy of this CEM varied between 35% and 100%, not 20% or less as required in the EPA performance specification. As a result, we conclude that no CEM is ready for long-term performance validation for compliance monitoring applications. Because sampling and measuring Hg is a recurring problem for multi-metal CEMs as well as Hg CEMs, we recommended that developers participate in a 1998 DOE-sponsored workshop to solve these and other common CEM measurement issues.

  10. Serpentine bacteria influence metal translocation and bioconcentration of Brassica juncea and Ricinus communis grown in multi-metal polluted soils.

    PubMed

    Ma, Ying; Rajkumar, Mani; Rocha, Inês; Oliveira, Rui S; Freitas, Helena

    2014-01-01

    The aim of this study was to assess the effects of inoculation of rhizosphere or endophytic bacteria (Psychrobacter sp. SRS8 and Pseudomonas sp. A3R3, respectively) isolated from a serpentine environment on the plant growth and the translocation and accumulation of Ni, Zn, and Fe by Brassica juncea and Ricinus communis on a multi-metal polluted serpentine soil (SS). Field collected SS was diluted to 0, 25, 50, and 75% with pristine soil in order to obtain a range of heavy metal concentrations and used in microcosm experiments. Regardless of inoculation with bacteria, the biomass of both plant species decreased with increase of the proportion of SS. Inoculation of plants with bacteria significantly increased the plant biomass and the heavy metal accumulation compared with non-inoculated control in the presence of different proportion of SS, which was attributed to the production of plant growth promoting and/or metal mobilizing metabolites by bacteria. However, SRS8 showed a maximum increase in the biomass of the test plants grown even in the treatment of 75% SS. In turn, A3R3 showed maximum effects on the accumulation of heavy metals in both plants. Regardless of inoculation of bacteria and proportion of SS, both plant species exhibited low values of bioconcentration factor (<1) for Ni and Fe. The inoculation of both bacterial strains significantly increased the translocation factor (TF) of Ni while decreasing the TF of Zn in both plant species. Besides this contrasting effect, the TFs of all metals were <1, indicating that all studied bacteria-plant combinations are suitable for phytostabilization. This study demonstrates that the bacterial isolates A3R3 and SRS8 improved the growth of B. juncea and R. communis in SS soils and have a great potential to be used as inoculants in phytostabilization scenarios of multi-metal contaminated soils.

  11. Serpentine bacteria influence metal translocation and bioconcentration of Brassica juncea and Ricinus communis grown in multi-metal polluted soils

    PubMed Central

    Ma, Ying; Rajkumar, Mani; Rocha, Inês; Oliveira, Rui S.; Freitas, Helena

    2015-01-01

    The aim of this study was to assess the effects of inoculation of rhizosphere or endophytic bacteria (Psychrobacter sp. SRS8 and Pseudomonas sp. A3R3, respectively) isolated from a serpentine environment on the plant growth and the translocation and accumulation of Ni, Zn, and Fe by Brassica juncea and Ricinus communis on a multi-metal polluted serpentine soil (SS). Field collected SS was diluted to 0, 25, 50, and 75% with pristine soil in order to obtain a range of heavy metal concentrations and used in microcosm experiments. Regardless of inoculation with bacteria, the biomass of both plant species decreased with increase of the proportion of SS. Inoculation of plants with bacteria significantly increased the plant biomass and the heavy metal accumulation compared with non-inoculated control in the presence of different proportion of SS, which was attributed to the production of plant growth promoting and/or metal mobilizing metabolites by bacteria. However, SRS8 showed a maximum increase in the biomass of the test plants grown even in the treatment of 75% SS. In turn, A3R3 showed maximum effects on the accumulation of heavy metals in both plants. Regardless of inoculation of bacteria and proportion of SS, both plant species exhibited low values of bioconcentration factor (<1) for Ni and Fe. The inoculation of both bacterial strains significantly increased the translocation factor (TF) of Ni while decreasing the TF of Zn in both plant species. Besides this contrasting effect, the TFs of all metals were <1, indicating that all studied bacteria–plant combinations are suitable for phytostabilization. This study demonstrates that the bacterial isolates A3R3 and SRS8 improved the growth of B. juncea and R. communis in SS soils and have a great potential to be used as inoculants in phytostabilization scenarios of multi-metal contaminated soils. PMID:25601876

  12. Bacterial resistance to tetracycline: mechanisms, transfer, and clinical significance.

    PubMed Central

    Speer, B S; Shoemaker, N B; Salyers, A A

    1992-01-01

    Tetracycline has been a widely used antibiotic because of its low toxicity and broad spectrum of activity. However, its clinical usefulness has been declining because of the appearance of an increasing number of tetracycline-resistant isolates of clinically important bacteria. Two types of resistance mechanisms predominate: tetracycline efflux and ribosomal protection. A third mechanism of resistance, tetracycline modification, has been identified, but its clinical relevance is still unclear. For some tetracycline resistance genes, expression is regulated. In efflux genes found in gram-negative enteric bacteria, regulation is via a repressor that interacts with tetracycline. Gram-positive efflux genes appear to be regulated by an attenuation mechanism. Recently it was reported that at least one of the ribosome protection genes is regulated by attenuation. Tetracycline resistance genes are often found on transmissible elements. Efflux resistance genes are generally found on plasmids, whereas genes involved in ribosome protection have been found on both plasmids and self-transmissible chromosomal elements (conjugative transposons). One class of conjugative transposon, originally found in streptococci, can transfer itself from streptococci to a variety of recipients, including other gram-positive bacteria, gram-negative bacteria, and mycoplasmas. Another class of conjugative transposons has been found in the Bacteroides group. An unusual feature of the Bacteroides elements is that their transfer is enhanced by preexposure to tetracycline. Thus, tetracycline has the double effect of selecting for recipients that acquire a resistance gene and stimulating transfer of the gene. PMID:1423217

  13. Identification, characterization and antibiotic resistance of bacterial isolates obtained from waterpipe device hoses.

    PubMed

    Masadeh, Majed M; Hussein, Emad I; Alzoubi, Karem H; Khabour, Omar; Shakhatreh, Muhamad Ali K; Gharaibeh, Mahmoud

    2015-05-13

    The general lack of knowledge about the health effects of waterpipe smoking is among the reasons for its global spread. In this study, bacterial contamination of waterpipe hoses was investigated. Twenty hoses were collected from waterpipe cafés and screened for bacterial pathogens using standard culture and isolation techniques. Additionally, resistance of isolated bacteria to common antibiotics was determined by identifying the minimum inhibitory concentration (MIC) of each isolate. Forty eight bacterial isolates were detected. Isolates included both Gram-positive and Gram-negative pathogens from species that included Micrococcus (12), Corynebacterium (13) and Bacillus (9). In addition, some of the detected pathogens were found to be resistant to aztreonam (79%), cefixime (79%), norfloxacin, amoxicillin (47%), clarithromycin (46%) and enrofloxacin (38%). In conclusion, the hose of the waterpipe device is a good environment for the growth of bacterial pathogens, which can then be transmitted to users.

  14. Comparison of monometal and multimetal adsorption in Mississippi River alluvial wetland sediment: batch and column experiments.

    PubMed

    Seo, Dong Cheol; Yu, Kewei; DeLaune, Ronald D

    2008-12-01

    Monometal and multimetal adsorption of selected heavy metals in a sediment from a coastal Louisiana forested swamp used for wastewater treatment was studied. Results from the batch experiments show that the maximum adsorption capacities of the metals by the sediment were in the order of Pb>Hg>Cr>CdCuZn>As based on monometal adsorption isotherm, and Hg>Cr>CuCd approximately Pb>As approximately Zn based on multimetal adsorption isotherm, respectively. Batch experimental data best fit the Langmuir model rather than the Freundlich isotherms. In the column experiments, the maximum adsorption capacities of the metals were in the order of Pb>Hg>Cr>Cd>Cu>Zn>As in monometal conditions, and Hg>Cr>Pb>CuZn approximately Cd>As in multimetal conditions. The metals became more mobile in multimetal than in monometal conditions. Results from both the batch and column experiments show that competitive adsorption among metals increases the mobility of these metals. Particularly, in this study, Pb in multimetal conditions lost it adsorption capacity most significantly. In both monometal and multimetal conditions, the maximum adsorption capacity of the metals in the column experiments was higher than that in the batch experiment indicating other metal retention mechanisms rather than adsorption may be involved. Therefore, both column and batch experiments are needed for estimating retention capacities and removal efficiencies of metals in sediments.

  15. Adaptation or selection? Old issues and new stakes in the postwar debates over bacterial drug resistance.

    PubMed

    Creager, Angela N H

    2007-03-01

    The 1940s and 1950s were marked by intense debates over the origin of drug resistance in microbes. Bacteriologists had traditionally invoked the notions of 'training' and 'adaptation' to account for the ability of microbes to acquire new traits. As the field of bacterial genetics emerged, however, its participants rejected 'Lamarckian' views of microbial heredity, and offered statistical evidence that drug resistance resulted from the selection of random resistant mutants. Antibiotic resistance became a key issue among those disputing physiological (usually termed 'adaptationist') vs. genetic (mutation and selection) explanations of variation in bacteria. Postwar developments connected with the Lysenko affair gave this debate a new political valence. Proponents of the neo-Darwinian synthesis weighed in with support for the genetic theory. However, certain features of drug resistance seemed inexplicable by mutation and selection, particularly the phenomenon of 'multiple resistance'--the emergence of resistance in a single strain against several unrelated antibiotics. In the late 1950s, Tsutomu Watanabe and his collaborators solved this puzzle by determining that resistance could be conferred by cytoplasmic resistance factors rather than chromosomal mutation. These R factors could carry resistance to many antibiotics and seemed able to promote their own dissemination in bacterial populations. In the end, the vindication of the genetic view of drug resistance was accompanied by a recasting of the 'gene' to include extrachromosomal hereditary units carried on viruses and plasmids.

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

    PubMed

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

    2015-10-20

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

  17. Bacterial antibiotic resistance in soils irrigated with reclaimed municipal wastewater

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wastewater reclamation for municipal irrigation and groundwater recharge is an increasingly attractive option for extending water supplies. However, public health concerns include the potential for development of antibiotic resistance (AR) in soil bacteria after exposure to residual chemicals in rec...

  18. A recent evaluation of empirical cephalosporin treatment and antibiotic resistance of changing bacterial profiles in spontaneous bacterial peritonitis.

    PubMed

    Yakar, Tolga; Güçlü, Mustafa; Serin, Ender; Alişkan, Hikmet; Husamettin, Erdamar

    2010-04-01

    The aim of this research is to evaluate the recent changes in microorganisms causing spontaneous bacterial peritonitis in cirrhotic patients, antibiotic resistance, and response to empirical cephalosporin therapy. A total of 218 patients with ascites secondary to cirrhosis were enrolled. Parenteral cefotaxime or cefepime was given to patients who had a neutrophil count of 250/mm(3) or more or a positive bacterial culture of ascitic fluid. Antibiotic failure was defined by an absence of clinical improvement and an insufficient decrease in neutrophil count of ascites (<25% of initial value) by the third day of therapy. Of all the patients, 44.6% had culture-negative neutrocytic ascites, 24.8% had spontaneous bacterial peritonitis, and 10.1% had monomicrobial nonneutrocytic bacterascites. Growth in culture was observed in 76 patients (34.9%). The two most common isolated bacteria were Escherichia coli (33.8%) and coagulase-negative Staphylococcus (CoNS; 19.7%). The two cephalosporins were effective against E. coli (82%) and but not against CoNS (44%), while levofloxacin showed reasonable activity against both E. coli (71%) and CoNS (90%) in vitro. We confirmed a recent increased incidence of spontaneous bacterial peritonitis caused by Gram-positive bacteria. Levofloxacin seems to be a good alternative treatment for patients with uncomplicated spontaneous ascites infections.

  19. Development of a Protocol for Predicting Bacterial Resistance to Microbicides

    PubMed Central

    Knapp, Laura; Amézquita, Alejandro; McClure, Peter; Stewart, Sara

    2015-01-01

    Regulations dealing with microbicides in Europe and the United States are evolving and now require data on the risk of the development of resistance in organisms targeted by microbicidal products. There is no standard protocol to assess the risk of the development of resistance to microbicidal formulations. This study aimed to validate the use of changes in microbicide and antibiotic susceptibility as initial markers for predicting microbicide resistance and cross-resistance to antibiotics. Three industrial isolates (Pseudomonas aeruginosa, Burkholderia cepacia, and Klebsiella pneumoniae) and two Salmonella enterica serovar Typhimurium strains (SL1344 and 14028S) were exposed to a shampoo, a mouthwash, eye makeup remover, and the microbicides contained within these formulations (chlorhexidine digluconate [CHG] and benzalkonium chloride [BZC]) under realistic, in-use conditions. Baseline and postexposure data were compared. No significant increases in the MIC or the minimum bactericidal concentration (MBC) were observed for any strain after exposure to the three formulations. Increases as high as 100-fold in the MICs and MBCs of CHG and BZC for SL1344 and 14028S were observed but were unstable. Changes in antibiotic susceptibility were not clinically significant. The use of MICs and MBCs combined with antibiotic susceptibility profiling and stability testing generated reproducible data that allowed for an initial prediction of the development of resistance to microbicides. These approaches measure characteristics that are directly relevant to the concern over resistance and cross-resistance development following the use of microbicides. These are low-cost, high-throughput techniques, allowing manufacturers to provide to regulatory bodies, promptly and efficiently, data supporting an early assessment of the risk of resistance development. PMID:25636848

  20. 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

  1. Correlation Models between Environmental Factors and Bacterial Resistance to Antimony and Copper

    PubMed Central

    Shi, Zunji; Cao, Zhan; Qin, Dong; Zhu, Wentao; Wang, Qian; Li, Mingshun; Wang, Gejiao

    2013-01-01

    Antimony (Sb) and copper (Cu) are toxic heavy metals that are associated with a wide variety of minerals. Sb(III)-oxidizing bacteria that convert the toxic Sb(III) to the less toxic Sb(V) are potentially useful for environmental Sb bioremediation. A total of 125 culturable Sb(III)/Cu(II)-resistant bacteria from 11 different types of mining soils were isolated. Four strains identified as Arthrobacter, Acinetobacter and Janibacter exhibited notably high minimum inhibitory concentrations (MICs) for Sb(III) (>10 mM),making them the most highly Sb(III)-resistant bacteria to date. Thirty-six strains were able to oxidize Sb(III), including Pseudomonas-, Comamonas-, Acinetobacter-, Sphingopyxis-, Paracoccus- Aminobacter-, Arthrobacter-, Bacillus-, Janibacter- and Variovorax-like isolates. Canonical correspondence analysis (CCA) revealed that the soil concentrations of Sb and Cu were the most obvious environmental factors affecting the culturable bacterial population structures. Stepwise linear regression was used to create two predictive models for the correlation between soil characteristics and the bacterial Sb(III) or Cu(II) resistance. The concentrations of Sb and Cu in the soil was the significant factors affecting the bacterial Sb(III) resistance, whereas the concentrations of S and P in the soil greatly affected the bacterial Cu(II) resistance. The two stepwise linear regression models that we derived are as follows: and [where the MICSb(III) and MICCu(II) represent the average bacterial MIC for the metal of each soil (µM), and the CSb, CCu, CS and CP represent concentrations for Sb, Cu, S and P (mg/kg) in soil, respectively, p<0.01]. The stepwise linear regression models we developed suggest that metals as well as other soil physicochemical parameters can contribute to bacterial resistance to metals. PMID:24205252

  2. Using experimental evolution to explore natural patterns between bacterial motility and resistance to bacteriophages.

    PubMed

    Koskella, Britt; Taylor, Tiffany B; Bates, Jennifer; Buckling, Angus

    2011-11-01

    Resistance of bacteria to phages may be gained by alteration of surface proteins to which phages bind, a mechanism that is likely to be costly as these molecules typically have critical functions such as movement or nutrient uptake. To address this potential trade-off, we combine a systematic study of natural bacteria and phage populations with an experimental evolution approach. We compare motility, growth rate and susceptibility to local phages for 80 bacteria isolated from horse chestnut leaves and, contrary to expectation, find no negative association between resistance to phages and bacterial motility or growth rate. However, because correlational patterns (and their absence) are open to numerous interpretations, we test for any causal association between resistance to phages and bacterial motility using experimental evolution of a subset of bacteria in both the presence and absence of naturally associated phages. Again, we find no clear link between the acquisition of resistance and bacterial motility, suggesting that for these natural bacterial populations, phage-mediated selection is unlikely to shape bacterial motility, a key fitness trait for many bacteria in the phyllosphere. The agreement between the observed natural pattern and the experimental evolution results presented here demonstrates the power of this combined approach for testing evolutionary trade-offs.

  3. Targeting bacterial adherence inhibits multidrug-resistant Pseudomonas aeruginosa infection following burn injury

    PubMed Central

    Huebinger, Ryan M.; Stones, Daniel H.; de Souza Santos, Marcela; Carlson, Deborah L.; Song, Juquan; Vaz, Diana Pereira; Keen, Emma; Wolf, Steven E.; Orth, Kim; Krachler, Anne Marie

    2016-01-01

    Classical antimicrobial drugs target proliferation and therefore place microbes under extreme selective pressure to evolve resistance. Alternative drugs that target bacterial virulence without impacting survival directly offer an attractive solution to this problem, but to date few such molecules have been discovered. We previously discovered a widespread group of bacterial adhesins, termed Multivalent Adhesion Molecules (MAMs) that are essential for initial binding of bacteria to host tissues and virulence. Thus, targeting MAM-based adherence is a promising strategy for displacing pathogens from host tissues and inhibiting infection. Here, we show that topical application of polymeric microbeads functionalized with the adhesin MAM7 to a burn infected with multidrug-resistant Pseudomonas aeruginosa substantially decreased bacterial loads in the wound and prevented the spread of the infection into adjacent tissues. As a consequence, the application of this adhesion inhibitor allowed for vascularization and wound healing, and maintained local and systemic inflammatory responses to the burn. We propose that MAM7-functionalized microbeads can be used as a topical treatment, to reduce bacterial attachment and hence prevent bacterial colonization and infection of wounds. As adhesion is not required for microbial survival, this anti-infective strategy has the potential to treat multidrug-resistant infections and limit the emergence of drug-resistant pathogens. PMID:27996032

  4. A new common bacterial blight resistance QTL in VAX 1 common bean and interaction of the new QTL, SAP6 and SU91 with bacterial strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common bacterial blight (CBB) is a severe disease in common bean. New resistance QTL should facilitate development of cultivars with high levels of resistance. Our objectives were to (i) identify new resistance QTL in VAX 1 and verify presence in VAX 3, (ii) determine interaction of new QTL with exi...

  5. Trends in bacterial resistance in a tertiary university hospital over one decade.

    PubMed

    Rubio, Fernando Góngora; Oliveira, Viviane Decicera Colombo; Rangel, Regina Mara Custódio; Nogueira, Mara Corrêa Lelles; Almeida, Margarete Teresa Gottardo

    2013-01-01

    The objective of this study was to investigate bacterial resistance trends, infection sites and the relationship between resistance and admittance to the intensive care unit (ICU). A total of 53,316 bacteria identified between 1999 and 2008 were evaluated. Multidrug resistance was characterized when gram-negative bacilli (GNB) presented resistance to two or more classes of antibiotics. Gram-positive cocci (CPC) were assessed for resistance to penicillin, oxacillin and vancomycin. GNB were the most common (66.1%) isolate. There was a 3.7-fold overall increase in multidrug resistant GNB over the study period; Acinetobacter baumanii and Staphylococcus aureus were the most prevalent. Highest increases were recorded for Klebsiella pneumoniae (14.6-fold) and enterococci (73-fold). The resistance rates for GNB and GPC were 36% and 51.7%, respectively. Most multidrug resistant GNB and GPC were recovered from ICU patients (p-value<0.001). Vancomycin-resistant enterococci were isolated during this decade with an increase of 18.7% by 2008. These data confirm the worldwide trend in multidrug bacterial resistance.

  6. Interferon in resistance to bacterial and protozoan infections

    NASA Technical Reports Server (NTRS)

    Sonnenfeld, Gerald; Gould, Cheryl L.; Kierszenbaum, Felipe; Degee, Antonie L. W.; Mansfield, John M.

    1986-01-01

    The effects of genetic differences in mouse strains on the modulation of protozoan infections by interferon (IFN) were investigated. In one set of experiments, three different strains of mice were injected with T. cruzi, and their sera were assayed at five time intervals for IFN titer. A greater quantity of IFN was produced by mouse strains that were susceptible to T. cruzi infection than by the more resistant strain. In another set of experiments, spleen cell cultures from inbred strains of mice were challenged with an antigen made from T.b. rhodesiense. The cells from mice resistant to infection, produced greater amounts of IFN-gamma than did cells from the susceptible mice. In a third set of experiments, it was found that mice injected with T.b. rhodesiense before being infected with a diabetogenic virus (EMC-D) were resistant to the effects of the virus and did not produce virus-specific antibody.

  7. Safety and effectiveness of home intravenous antibiotic therapy for multidrug-resistant bacterial infections.

    PubMed

    Mujal, A; Sola, J; Hernandez, M; Villarino, M-A; Machado, M-L; Baylina, M; Tajan, J; Oristrell, J

    2015-06-01

    Home intravenous antibiotic therapy is an alternative to hospital admission for moderately severe infections. However, few studies have analyzed its safety and effectiveness in the treatment of infections caused by multidrug-resistant bacteria. The purpose of this study is to analyze the safety and effectiveness of home intravenous antibiotic therapy in multidrug-resistant bacterial infections. We analyzed prospectively all patients admitted to our service who underwent home intravenous antibiotic therapy during the period 2008-2012. All the treatments were administered by caretakers or self-administered by patients, through elastomeric infusion devices. Effectiveness was evaluated by analyzing the readmission rate for poor infection control. Safety was evaluated by analyzing adverse events, catheter-related complications, and readmissions not related to poor infection control. There were 433 admissions (in 355 patients) for home intravenous antibiotic therapy during the study period. There were 226 (52.2 %) admissions due to multidrug-resistant bacterial infections and 207 (47.8 %) due to non-multidrug-resistant infections. Hospital readmissions in patients with multidrug-resistant infections were uncommon. Multidrug-resistant enterococcal infections, healthcare-associated infections, and carbapenem therapy were independent variables associated with increased readmissions due to poor infection control. Readmissions not related to poor infection control, adverse events, and catheter-related complications were similar in multidrug-resistant compared to non-multidrug-resistant bacterial infections. Home intravenous therapy, administered by patients or their caretakers using elastomeric infusion pumps, was safe and effective for the treatment of most multidrug-resistant bacterial infections.

  8. Antimicrobial Resistance and Virulence: a Successful or Deleterious Association in the Bacterial World?

    PubMed Central

    Beceiro, Alejandro; Tomás, María

    2013-01-01

    SUMMARY Hosts and bacteria have coevolved over millions of years, during which pathogenic bacteria have modified their virulence mechanisms to adapt to host defense systems. Although the spread of pathogens has been hindered by the discovery and widespread use of antimicrobial agents, antimicrobial resistance has increased globally. The emergence of resistant bacteria has accelerated in recent years, mainly as a result of increased selective pressure. However, although antimicrobial resistance and bacterial virulence have developed on different timescales, they share some common characteristics. This review considers how bacterial virulence and fitness are affected by antibiotic resistance and also how the relationship between virulence and resistance is affected by different genetic mechanisms (e.g., coselection and compensatory mutations) and by the most prevalent global responses. The interplay between these factors and the associated biological costs depend on four main factors: the bacterial species involved, virulence and resistance mechanisms, the ecological niche, and the host. The development of new strategies involving new antimicrobials or nonantimicrobial compounds and of novel diagnostic methods that focus on high-risk clones and rapid tests to detect virulence markers may help to resolve the increasing problem of the association between virulence and resistance, which is becoming more beneficial for pathogenic bacteria. PMID:23554414

  9. Pyramiding B genes in cotton achieves broader but not always higher resistance to bacterial blight.

    PubMed

    Essenberg, Margaret; Bayles, Melanie B; Pierce, Margaret L; Verhalen, Laval M

    2014-10-01

    Near-isogenic lines of upland cotton (Gossypium hirsutum) carrying single, race-specific genes B4, BIn, and b7 for resistance to bacterial blight were used to develop a pyramid of lines with all possible combinations of two and three genes to learn whether the pyramid could achieve broad and high resistance approaching that of L. A. Brinkerhoff's exceptional line Im216. Isogenic strains of Xanthomonas axonopodis pv. malvacearum carrying single avirulence (avr) genes were used to identify plants carrying specific resistance (B) genes. Under field conditions in north-central Oklahoma, pyramid lines exhibited broader resistance to individual races and, consequently, higher resistance to a race mixture. It was predicted that lines carrying two or three B genes would also exhibit higher resistance to race 1, which possesses many avr genes. Although some enhancements were observed, they did not approach the level of resistance of Im216. In a growth chamber, bacterial populations attained by race 1 in and on leaves of the pyramid lines decreased significantly with increasing number of B genes in only one of four experiments. The older lines, Im216 and AcHR, exhibited considerably lower bacterial populations than any of the one-, two-, or three-B-gene lines. A spreading collapse of spray-inoculated AcBIn and AcBInb7 leaves appears to be a defense response (conditioned by BIn) that is out of control.

  10. PREVALENCE OF BACTERIAL RESISTANCE IN HOSPITALIZED CIRRHOTIC PATIENTS IN SOUTHERN BRAZIL: A NEW CHALLENGE

    PubMed Central

    COSTABEBER, Ane Micheli; de MATTOS, Angelo Alves; SUKIENNIK, Teresa Cristina Teixeira

    2016-01-01

    Background & Aims: An increased frequency of infections by multiresistant bacteria has been described in hospitalized patients. The aim of this study was to evaluate the bacterial resistance profile in cirrhotic patients. Methods: This is a retrospective observational study. We assessed the antimicrobial susceptibility of 5,839 bacterial isolates from patients with and without cirrhosis. Regarding the multidrug resistance, we evaluated 4,505 bacterial isolates from 2,180 patients. Results: Two hundred and fifty-one patients had cirrhosis (mean age 57.6 ± 11 years; 61.8% were male, 47.8% of cases associated with hepatitis C virus). Of the isolates of patients with and without cirrhosis, 174/464 (37.5%) and 1,783/4,041 (44.1%) were multiresistant, respectively (p = 0.007). E. coli was the most common multiresistant bacteria in both groups. Approximately 20% of E. coli and Klebsiella sp. isolates were ESBL-producers and 44% of S. aureus isolates were methicillin-resistant in cirrhotic patients. In cirrhotic patients admitted to the emergency department, hospital ward, and intensive care unit, 28.3%, 50% and 40% had multiresistant isolates, respectively. In patients with and without cirrhosis, 36.2% and 33.5% of isolates were resistant to third-generation cephalosporins, respectively. Conclusions: The empirical treatment of infections in hospitalized patients using broad-spectrum antibiotics should consider the observed pattern of bacterial resistance. PMID:27253738

  11. Induced Bacterial Cross-Resistance toward Host Antimicrobial Peptides: A Worrying Phenomenon

    PubMed Central

    Fleitas, Osmel; Franco, Octávio L.

    2016-01-01

    Bacterial resistance to conventional antibiotics has reached alarming levels, threatening to return to the pre-antibiotic era. Therefore, the search for new antimicrobial compounds that overcome the resistance phenomenon has become a priority. Antimicrobial peptides (AMPs) appear as one of the most promising antibiotic medicines. However, in recent years several AMP-resistance mechanisms have been described. Moreover, the AMP-resistance phenomenon has become more complex due to its association with cross-resistance toward AMP effectors of the host innate immune system. In this context, the use of AMPs as a therapeutic option could be potentially hazardous, since bacteria could develop resistance toward our innate immune system. Here, we review the findings of major studies that deal with the AMP cross-resistance phenomenon. PMID:27047486

  12. Induced Bacterial Cross-Resistance toward Host Antimicrobial Peptides: A Worrying Phenomenon.

    PubMed

    Fleitas, Osmel; Franco, Octávio L

    2016-01-01

    Bacterial resistance to conventional antibiotics has reached alarming levels, threatening to return to the pre-antibiotic era. Therefore, the search for new antimicrobial compounds that overcome the resistance phenomenon has become a priority. Antimicrobial peptides (AMPs) appear as one of the most promising antibiotic medicines. However, in recent years several AMP-resistance mechanisms have been described. Moreover, the AMP-resistance phenomenon has become more complex due to its association with cross-resistance toward AMP effectors of the host innate immune system. In this context, the use of AMPs as a therapeutic option could be potentially hazardous, since bacteria could develop resistance toward our innate immune system. Here, we review the findings of major studies that deal with the AMP cross-resistance phenomenon.

  13. Increase of multi-metal tolerance of three leguminous plants by arbuscular mycorrhizal fungi colonization.

    PubMed

    Lin, Ai-Jun; Zhang, Xu-Hong; Wong, Ming-Hung; Ye, Zhi-Hong; Lou, Lai-Qing; Wang, You-Shan; Zhu, Yong-Guan

    2007-12-01

    A greenhouse pot experiment was conducted to investigate the effects of the colonization of arbuscular mycorrhizal fungus (AMF) Glomus mosseae on the growth and metal uptake of three leguminous plants (Sesbania rostrata, Sesbania cannabina, Medicago sativa) grown in multi-metal contaminated soil. AMF colonization increased the growth of the legumes, indicating that AMF colonization increased the plant's resistance to heavy metals. It also significantly stimulated the formation of root nodules and increased the N and P uptake of all of the tested leguminous plants, which might be one of the tolerance mechanisms conferred by AMF. Compared with the control, colonization by G. mosseae decreased the concentration of metals, such as Cu, in the shoots of the three legumes, indicating that the decreased heavy metals uptake and growth dilution were induced by AMF treatment, thereby reducing the heavy metal toxicity to the plants. The root/shoot ratios of Cu in the three legumes and Zn in M. sativa were significantly increased (P<0.05) with AMF colonization, indicating that heavy metals were immobilized by the mycorrhiza and the heavy metal translocations to the shoot were decreased.

  14. [The fight against bacterial resistance, a public health priority].

    PubMed

    Carlet, Jean

    2015-01-01

    The increase in the number of antibiotic resistant bacteria represents a major danger for the health of humans and animals. Combined with an almost complete absence of new antibiotics, it is one of the most alarming public health issues of our time. Measures must be taken in order to control the use of these drugs and safeguard their effectiveness.

  15. Use of phenotype microarrays to study the effect of acquisition of resistance to antimicrobials in bacterial physiology.

    PubMed

    Reales-Calderon, Jose A; Blanco, Paula; Alcalde-Rico, Manuel; Corona, Fernando; Lira, Felipe; Hernando-Amado, Sara; Bernardini, Alejandra; Sánchez, María B; Martínez, José L

    It is widely accepted that the acquisition of resistance to antimicrobials confers a fitness cost. Different works have shown that the effect of acquiring resistance in bacterial physiology may be more specific than previously thought. Study of these specific changes may help to predict the outcome of resistant organisms in different ecosystems. In addition to changing bacterial physiology, acquisition of resistance either increases or reduces susceptibility to other antimicrobials. In the current article, we review recent information on the effect of acquiring resistance upon bacterial physiology, with a specific focus on studies using phenotype microarray technology.

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

    PubMed Central

    Tillotson, Glenn S.

    2016-01-01

    Antibiotic resistance has been emerged as a major global health problem. In particular, gram-negative species pose a significant clinical challenge as bacteria develop or acquire more resistance mechanisms. Often, these bacteria possess multiple resistance mechanisms, thus nullifying most of the major classes of drugs. Novel approaches to this issue are urgently required. However, the challenges of developing new agents are immense. Introducing novel agents is fraught with hurdles, thus adapting known antibiotic classes by altering their chemical structure could be a way forward. A chemical addition to existing antibiotics known as a siderophore could be a solution to the gram-negative resistance issue. Siderophore molecules rely on the bacterial innate need for iron ions and thus can utilize a Trojan Horse approach to gain access to the bacterial cell. The current approaches to using this potential method are reviewed. PMID:27773991

  17. Interfamily transfer of a plant pattern-recognition receptor confers broad-spectrum bacterial resistance.

    PubMed

    Lacombe, Séverine; Rougon-Cardoso, Alejandra; Sherwood, Emma; Peeters, Nemo; Dahlbeck, Douglas; van Esse, H Peter; Smoker, Matthew; Rallapalli, Ghanasyam; Thomma, Bart P H J; Staskawicz, Brian; Jones, Jonathan D G; Zipfel, Cyril

    2010-04-01

    Plant diseases cause massive losses in agriculture. Increasing the natural defenses of plants may reduce the impact of phytopathogens on agricultural productivity. Pattern-recognition receptors (PRRs) detect microbes by recognizing conserved pathogen-associated molecular patterns (PAMPs). Although the overall importance of PAMP-triggered immunity for plant defense is established, it has not been used to confer disease resistance in crops. We report that activity of a PRR is retained after its transfer between two plant families. Expression of EFR (ref. 4), a PRR from the cruciferous plant Arabidopsis thaliana, confers responsiveness to bacterial elongation factor Tu in the solanaceous plants Nicotiana benthamiana and tomato (Solanum lycopersicum), making them more resistant to a range of phytopathogenic bacteria from different genera. Our results in controlled laboratory conditions suggest that heterologous expression of PAMP recognition systems could be used to engineer broad-spectrum disease resistance to important bacterial pathogens, potentially enabling more durable and sustainable resistance in the field.

  18. Quantitative trait Loci mapping for bacterial blight resistance in rice using bulked segregant analysis.

    PubMed

    Han, Xueying; Yang, Yong; Wang, Xuming; Zhou, Jie; Zhang, Wenhao; Yu, Chulang; Cheng, Chen; Cheng, Ye; Yan, Chengqi; Chen, Jianping

    2014-07-03

    Oryza meyeriana is highly resistant to rice bacterial blight (BB) and this resistance trait has been transferred to cultivated rice (O. sativa) using asymmetric somatic hybridization. However, no resistance genes have yet been cloned. In the present study, a progeny of the somatic hybridization with high BB resistance was crossed with a rice cultivar with high BB susceptibility to develop an F2 population. Using bulked segregant analysis (BSA), 17 polymorphic markers that were linked to rice BB resistance were obtained through scanning a total of 186 simple sequence repeats (SSR) and sequence-tagged site (STS) markers, evenly distributed on 12 chromosomes. A genetic linkage map was then constructed based on the 17 linkage markers and the F2 segregating population, which was followed by mapping for quantitative trait loci (QTLs) for BB resistance. Three QTLs were identified on chromosomes 1, 3 and 5, respectively, and the alleles of the resistant parent at any of the QTLs increased BB resistance. All of the three QTLs had a strong effect on resistance, explaining about 21.5%, 12.3% and 39.2% of the resistance variance, respectively. These QTLs were different from the loci of the BB resistance genes that have been identified in previous studies. The QTLs mapped in this work will facilitate the isolation of novel BB resistance genes and their utilization in rice resistance breeding.

  19. Mosquitocidal bacterial toxins: diversity, mode of action and resistance phenomena.

    PubMed

    Charles, J F; Nielsen-LeRoux, C

    2000-01-01

    Bacteria active against dipteran larvae (mosquitoes and black flies) include a wide variety of Bacillus thuringiensis and B. sphaericus strains, as well as isolates of Brevibacillus laterosporus and Clostridium bifermentans. All display different spectra and levels of activity correlated with the nature of the toxins, mainly produced during the sporulation process. This paper describes the structure and mode of action of the main mosquitocidal toxins, in relationship with their potential use in mosquito and/or black fly larvae control. Investigations with laboratory and field colonies of mosquitoes that have become highly resistant to the B. sphaericus Bin toxin have shown that several mechanisms of resistance are involved, some affecting the toxin/receptor binding step, others unknown.

  20. Insights into the amplification of bacterial resistance to erythromycin in activated sludge.

    PubMed

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

    2015-10-01

    Wastewater treatment plants are significant reservoirs for antimicrobial resistance. However, little is known about wastewater treatment effects on the variation of antibiotic resistance. The shifts of bacterial resistance to erythromycin, a macrolide widely used in human medicine, on a lab-scale activated sludge system fed with real wastewater was investigated from levels of bacteria, community and genes, in this study. The resistance variation of total heterotrophic bacteria was studied during the biological treatment process, based on culture dependent method. The alterations of bacterial community resistant to erythromycin and nine typical erythromycin resistance genes were explored with molecular approaches, including high-throughput sequencing and quantitative polymerase chain reaction. The results revealed that the total heterotrophs tolerance level to erythromycin concentrations (higher than 32 mg/L) was significantly amplified during the activated sludge treatment, with the prevalence increased from 9.6% to 21.8%. High-throughput sequencing results demonstrated an obvious increase of the total heterotrophic bacterial diversity resistant to erythromycin. Proteobacteria and Bacteroidetes were the two dominant phyla in the influent and effluent of the bioreactor. However, the prevalence of Proteobacteria decreased from 76% to 59% while the total phyla number increased greatly from 18 to 29 through activated sludge treatment. The gene proportions of erm(A), mef(E) and erm(D) were greatly amplified after biological treatment. It is proposed that the transfer of antibiotic resistance genes through the variable mixtures of bacteria in the activated sludge might be the reason for the antibiotic resistance amplification. The amplified risk of antibiotic resistance in wastewater treatment needs to be paid more attention.

  1. Antibiotic resistance, antimicrobial residues and bacterial community composition in urban wastewater.

    PubMed

    Novo, Ana; André, Sandra; Viana, Paula; Nunes, Olga C; Manaia, Célia M

    2013-04-01

    This study was based on the hypothesis that the occurrence of antimicrobial residues and antibiotic resistant bacteria in the sewage could be correlated with the structure and composition of the bacterial community and the antibiotic resistance loads of the final effluent. Raw and treated wastewater composite samples were collected from an urban treatment plant over 14 sampling dates. Samples were characterized for the i) occurrence of tetracyclines, penicillins, sulfonamides, quinolones, triclosan, arsenic, cadmium, lead, chromium and mercury; ii) antibiotic resistance percentages for tetracycline, sulfamethoxazole, ciprofloxacin and amoxicillin and iii) 16S rRNA gene-DGGE patterns. The data of corresponding samples, taking into account the hydraulic residence time, was analyzed using multivariate analysis. Variations on the bacterial community structure of the final effluent were significantly correlated with the occurrence of tetracyclines, penicillins, sulfonamides, quinolones and triclosan in the raw inflow. Members of the class Epsilonproteobacteria presented positive correlations with those antimicrobials, whereas negative correlations were observed with Beta and Gammaproteobacteria and Firmicutes. Antibiotic resistance percentages presented different trends of variation in heterotrophs/enterobacteria and in enterococci, varied over time and after wastewater treatment. Antibiotic resistance was positively correlated with the occurrence of tetracyclines residues and high temperature. A relationship between antibiotic residues, bacterial community structure and composition and antibiotic resistance is demonstrated. Further studies, involving more wastewater treatment plants may help to elucidate this complex relationship.

  2. Resistance of Aerosolized Bacterial Viruses to Relative Humidity and Temperature.

    PubMed

    Verreault, Daniel; Marcoux-Voiselle, Mélissa; Turgeon, Nathalie; Moineau, Sylvain; Duchaine, Caroline

    2015-10-01

    The use of aerosolized bacteriophages as surrogates for hazardous viruses might simplify and accelerate the discovery of links between viral components and their persistence in the airborne state under diverse environmental conditions. In this study, four structurally distinct lytic phages, MS2 (single-stranded RNA [ssRNA]), ϕ6 (double-stranded RNA [dsRNA]), ϕX174 (single-stranded DNA [ssDNA]), and PR772 (double-stranded DNA [dsDNA]), were nebulized into a rotating chamber and exposed to various levels of relative humidity (RH) and temperature as well as to germicidal UV radiation. The aerosolized viral particles were allowed to remain airborne for up to 14 h before being sampled for analysis by plaque assays and quantitative PCRs. Phages ϕ6 and MS2 were the most resistant at low levels of relative humidity, while ϕX174 was more resistant at 80% RH. Phage ϕ6 lost its infectivity immediately after exposure to 30°C and 80% RH. The infectivity of all tested phages rapidly declined as a function of the exposure time to UVC radiation, phage MS2 being the most resistant. Taken altogether, our data indicate that these aerosolized phages behave differently under various environmental conditions and highlight the necessity of carefully selecting viral simulants in bioaerosol studies.

  3. Resistance of Aerosolized Bacterial Viruses to Relative Humidity and Temperature

    PubMed Central

    Verreault, Daniel; Marcoux-Voiselle, Mélissa; Turgeon, Nathalie; Moineau, Sylvain

    2015-01-01

    The use of aerosolized bacteriophages as surrogates for hazardous viruses might simplify and accelerate the discovery of links between viral components and their persistence in the airborne state under diverse environmental conditions. In this study, four structurally distinct lytic phages, MS2 (single-stranded RNA [ssRNA]), ϕ6 (double-stranded RNA [dsRNA]), ϕX174 (single-stranded DNA [ssDNA]), and PR772 (double-stranded DNA [dsDNA]), were nebulized into a rotating chamber and exposed to various levels of relative humidity (RH) and temperature as well as to germicidal UV radiation. The aerosolized viral particles were allowed to remain airborne for up to 14 h before being sampled for analysis by plaque assays and quantitative PCRs. Phages ϕ6 and MS2 were the most resistant at low levels of relative humidity, while ϕX174 was more resistant at 80% RH. Phage ϕ6 lost its infectivity immediately after exposure to 30°C and 80% RH. The infectivity of all tested phages rapidly declined as a function of the exposure time to UVC radiation, phage MS2 being the most resistant. Taken altogether, our data indicate that these aerosolized phages behave differently under various environmental conditions and highlight the necessity of carefully selecting viral simulants in bioaerosol studies. PMID:26253683

  4. 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

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

    PubMed

    Hricová, Kristýna; Kolář, Milan

    2014-12-01

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

  6. Community-acquired methicillin-resistant Staphylococcus aureus: an emerging cause of acute bacterial parotitis.

    PubMed

    Nicolasora, Nelson P; Zacharek, Mark A; Malani, Anurag N

    2009-02-01

    Staphylococcus aureus has long been recognized as a cause of acute bacterial parotitis. A case of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) parotitis is presented, highlighting the emergence of this increasingly important pathogen to cause a wide variety of infections. Also reviewed are the salient clinical and microbiologic features of this novel infection.

  7. Response to selection for bacterial cold water disease resistance in rainbow trout

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A family-based selection program was initiated at the National Center for Cool and Cold Water Aquaculture in 2005 to improve resistance to bacterial cold water disease (BCWD) in rainbow trout. The objective of this study was to estimate response to 2 generations of selection. A total of 14,841 juven...

  8. Antibiotic exposure can induce various bacterial virulence phenotypes in multidrug-resistant Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella is one of the most prevalent bacterial foodborne diseases in the United States and causes an estimated 1 million human cases every year. Multidrug-resistant (MDR) Salmonella has emerged as a public health issue as it has been associated with increased morbidity in humans and mortality in...

  9. Development of candidate gene markers associated to common bacterial blight resistance in common bean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli (Xap), is a major yield-limiting factor of common bean (Phaseolus vulgaris L.) production around the world. Two major CBB-resistant quantitative trait loci (QTL), linked to the sequence characterized amplified region marker...

  10. 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

  11. Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance

    SciTech Connect

    Hoelzel, Christina S.; Mueller, Christa; Harms, Katrin S.; Mikolajewski, Sabine; Schaefer, Stefanie; Schwaiger, Karin; Bauer, Johann

    2012-02-15

    Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08-5.30 mg cadmium, 1.1-32.0 mg chrome, 22.4-3387.6 mg copper, <2.0-26.7 mg lead, <0.01-0.11 mg mercury, 3.1-97.3 mg nickel and 93.0-8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against {beta}-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against {beta}-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

  12. Antibiotic resistance among cultured bacterial isolates from bioethanol fermentation facilities across the United States.

    PubMed

    Murphree, Colin A; Heist, E Patrick; Moe, Luke A

    2014-09-01

    Bacterial contamination of fuel ethanol fermentations by lactic acid bacteria (LAB) can have crippling effects on bioethanol production. Producers have had success controlling bacterial growth through prophylactic addition of antibiotics to fermentors, yet concerns have arisen about antibiotic resistance among the LAB. Here, we report on mechanisms used by 32 LAB isolates from eight different US bioethanol facilities to persist under conditions of antibiotic stress. Minimum inhibitory concentration assays with penicillin, erythromycin, and virginiamycin revealed broad resistance to each of the antibiotics as well as high levels of resistance to individual antibiotics. Phenotypic assays revealed that antibiotic inactivation mechanisms contributed to the high levels of individual resistances among the isolates, especially to erythromycin and virginiamycin, yet none of the isolates appeared to use a β-lactamase. Biofilm formation was noted among the majority of the isolates and may contribute to persistence under low levels of antibiotics. Nearly all of the isolates carried at least one canonical antibiotic resistance gene and many carried more than one. The erythromycin ribosomal methyltransferase (erm) gene class was found in 19 of 32 isolates, yet a number of these isolates exhibit little to no resistance to erythromycin. The erm genes were present in 15 isolates that encoded more than one antibiotic resistance mechanism, suggestive of potential genetic linkages.

  13. Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance.

    PubMed

    Hölzel, Christina S; Müller, Christa; Harms, Katrin S; Mikolajewski, Sabine; Schäfer, Stefanie; Schwaiger, Karin; Bauer, Johann

    2012-02-01

    Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08-5.30 mg cadmium, 1.1-32.0 mg chrome, 22.4-3387.6 mg copper, <2.0-26.7 mg lead, <0.01-0.11 mg mercury, 3.1-97.3 mg nickel and 93.0-8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against β-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against β-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

  14. Stacking of antimicrobial genes in potato transgenic plants confers increased resistance to bacterial and fungal pathogens.

    PubMed

    Rivero, Mercedes; Furman, Nicolás; Mencacci, Nicolás; Picca, Pablo; Toum, Laila; Lentz, Ezequiel; Bravo-Almonacid, Fernando; Mentaberry, Alejandro

    2012-01-20

    Solanum tuberosum plants were transformed with three genetic constructions expressing the Nicotiana tabacum AP24 osmotine, Phyllomedusa sauvagii dermaseptin and Gallus gallus lysozyme, and with a double-transgene construction expressing the AP24 and lysozyme sequences. Re-transformation of dermaseptin-transformed plants with the AP24/lysozyme construction allowed selection of plants simultaneously expressing the three transgenes. Potato lines expressing individual transgenes or double- and triple-transgene combinations were assayed for resistance to Erwinia carotovora using whole-plant and tuber infection assays. Resistance levels for both infection tests compared consistently for most potato lines and allowed selection of highly resistant phenotypes. Higher resistance levels were found in lines carrying the dermaseptin and lysozyme sequences, indicating that theses proteins are the major contributors to antibacterial activity. Similar results were obtained in tuber infection tests conducted with Streptomyces scabies. Plant lines showing the higher resistance to bacterial infections were challenged with Phytophthora infestans, Rhizoctonia solani and Fusarium solani. Considerable levels of resistance to each of these pathogens were evidenced employing semi-quantitative tests based in detached-leaf inoculation, fungal growth inhibition and in vitro plant inoculation. On the basis of these results, we propose that stacking of these transgenes is a promising approach to achieve resistance to both bacterial and fungal pathogens.

  15. Engineering serendipity: High-throughput discovery of materials that resist bacterial attachment☆

    PubMed Central

    Magennis, E.P.; Hook, A.L.; Davies, M.C.; Alexander, C.; Williams, P.; Alexander, M.R.

    2016-01-01

    Controlling the colonisation of materials by microorganisms is important in a wide range of industries and clinical settings. To date, the underlying mechanisms that govern the interactions of bacteria with material surfaces remain poorly understood, limiting the ab initio design and engineering of biomaterials to control bacterial attachment. Combinatorial approaches involving high-throughput screening have emerged as key tools for identifying materials to control bacterial attachment. The hundreds of different materials assessed using these methods can be carried out with the aid of computational modelling. This approach can develop an understanding of the rules used to predict bacterial attachment to surfaces of non-toxic synthetic materials. Here we outline our view on the state of this field and the challenges and opportunities in this area for the coming years. Statement of significance This opinion article on high throughput screening methods reflects one aspect of how the field of biomaterials research has developed and progressed. The piece takes the reader through key developments in biomaterials discovery, particularly focusing on need to reduce bacterial colonisation of surfaces. Such bacterial resistant surfaces are increasingly required in this age of antibiotic resistance. The influence and origin of high-throughput methods are discussed with insights into the future of biomaterials development where computational methods may drive materials development into new fertile areas of discovery. New biomaterials will exhibit responsiveness to adapt to the biological environment and promote better integration and reduced rejection or infection. PMID:26577984

  16. Cultivable Bacterial Microbiota of Northern Bobwhite (Colinus virginianus): A New Reservoir of Antimicrobial Resistance?

    PubMed Central

    Su, Hongwen; McKelvey, Jessica; Rollins, Dale; Zhang, Michael; Brightsmith, Donald J.; Derr, James; Zhang, Shuping

    2014-01-01

    The northern bobwhite (Colinus virginianus) is an ecologically and economically important avian species. At the present time, little is known about the microbial communities associated with these birds. As the first step to create a quail microbiology knowledge base, the current study conducted an inventory of cultivable quail tracheal, crop, cecal, and cloacal microbiota and associated antimicrobial resistance using a combined bacteriology and DNA sequencing approach. A total of 414 morphologically unique bacterial colonies were selected from nonselective aerobic and anaerobic cultures, as well as selective and enrichment cultures. Analysis of the first 500-bp 16S rRNA gene sequences in conjunction with biochemical identifications revealed 190 non-redundant species-level taxonomic units, representing 160 known bacterial species and 30 novel species. The bacterial species were classified into 4 phyla, 14 orders, 37 families, and 59 or more genera. Firmicutes was the most commonly encountered phylum (57%) followed by Actinobacteria (24%), Proteobacteria (17%) and Bacteroidetes (0.02%). Extensive diversity in the species composition of quail microbiota was observed among individual birds and anatomical locations. Quail microbiota harbored several opportunistic pathogens, such as E. coli and Ps. aeruginosa, as well as human commensal organisms, including Neisseria species. Phenotypic characterization of selected bacterial species demonstrated a high prevalence of resistance to the following classes of antimicrobials: phenicol, macrolide, lincosamide, quinolone, and sulphate. Data from the current investigation warrant further investigation on the source, transmission, pathology, and control of antimicrobial resistance in wild quail populations. PMID:24937705

  17. Cultivable bacterial microbiota of northern bobwhite (Colinus virginianus): a new reservoir of antimicrobial resistance?

    PubMed

    Su, Hongwen; McKelvey, Jessica; Rollins, Dale; Zhang, Michael; Brightsmith, Donald J; Derr, James; Zhang, Shuping

    2014-01-01

    The northern bobwhite (Colinus virginianus) is an ecologically and economically important avian species. At the present time, little is known about the microbial communities associated with these birds. As the first step to create a quail microbiology knowledge base, the current study conducted an inventory of cultivable quail tracheal, crop, cecal, and cloacal microbiota and associated antimicrobial resistance using a combined bacteriology and DNA sequencing approach. A total of 414 morphologically unique bacterial colonies were selected from nonselective aerobic and anaerobic cultures, as well as selective and enrichment cultures. Analysis of the first 500-bp 16S rRNA gene sequences in conjunction with biochemical identifications revealed 190 non-redundant species-level taxonomic units, representing 160 known bacterial species and 30 novel species. The bacterial species were classified into 4 phyla, 14 orders, 37 families, and 59 or more genera. Firmicutes was the most commonly encountered phylum (57%) followed by Actinobacteria (24%), Proteobacteria (17%) and Bacteroidetes (0.02%). Extensive diversity in the species composition of quail microbiota was observed among individual birds and anatomical locations. Quail microbiota harbored several opportunistic pathogens, such as E. coli and Ps. aeruginosa, as well as human commensal organisms, including Neisseria species. Phenotypic characterization of selected bacterial species demonstrated a high prevalence of resistance to the following classes of antimicrobials: phenicol, macrolide, lincosamide, quinolone, and sulphate. Data from the current investigation warrant further investigation on the source, transmission, pathology, and control of antimicrobial resistance in wild quail populations.

  18. Bacterial glyphosate resistance conferred by overexpression of an E. coli membrane efflux transporter.

    PubMed

    Staub, Jeffrey M; Brand, Leslie; Tran, Minhtien; Kong, Yifei; Rogers, Stephen G

    2012-04-01

    Glyphosate herbicide-resistant crop plants, introduced commercially in 1994, now represent approximately 85% of the land area devoted to transgenic crops. Herbicide resistance in commercial glyphosate-resistant crops is due to expression of a variant form of a bacterial 5-enolpyruvylshikimate-3-phosphate synthase with a significantly decreased binding affinity for glyphosate at the target site of the enzyme. As a result of widespread and recurrent glyphosate use, often as the only herbicide used for weed management, increasing numbers of weedy species have evolved resistance to glyphosate. Weed resistance is most often due to changes in herbicide translocation patterns, presumed to be through the activity of an as yet unidentified membrane transporter in plants. To provide insight into glyphosate resistance mechanisms and identify a potential glyphosate transporter, we screened Escherichia coli genomic DNA for alternate sources of glyphosate resistance genes. Our search identified a single non-target gene that, when overexpressed in E. coli and Pseudomonas, confers high-level glyphosate resistance. The gene, yhhS, encodes a predicted membrane transporter of the major facilitator superfamily involved in drug efflux. We report here that an alternative mode of glyphosate resistance in E. coli is due to reduced accumulation of glyphosate in cells that overexpress this membrane transporter and discuss the implications for potential alternative resistance mechanisms in other organisms such as plants.

  19. Potential strategies for the eradication of multidrug-resistant Gram-negative bacterial infections.

    PubMed

    Huwaitat, Rawan; McCloskey, Alice P; Gilmore, Brendan F; Laverty, Garry

    2016-07-01

    Antimicrobial resistance is one of the leading threats to society. The increasing burden of multidrug-resistant Gram-negative infection is particularly concerning as such bacteria are demonstrating resistance to nearly all currently licensed therapies. Various strategies have been hypothesized to treat multidrug-resistant Gram-negative infections including: targeting the Gram-negative outer membrane; neutralization of lipopolysaccharide; inhibition of bacterial efflux pumps and prevention of protein folding. Silver and silver nanoparticles, fusogenic liposomes and nanotubes are potential strategies for extending the activity of licensed, Gram-positive selective, antibiotics to Gram-negatives. This may serve as a strategy to fill the current void in pharmaceutical development in the short term. This review outlines the most promising strategies that could be implemented to solve the threat of multidrug-resistant Gram-negative infections.

  20. Screening for antimicrobial resistance in normal bacterial flora of the skin using the replica plating method.

    PubMed

    Paavilainen, T; Osterblad, M; Leistevuo, T; Huovinen, P; Kotilainen, P

    2000-12-01

    The replica plating method was evaluated for detection of the antimicrobial resistance of normal bacterial flora of the skin and was compared with the results of a ten-colony method. If > or = 10% of the colonies from the master plate grew on a plate containing an antibiotic, the sensitivity of replica plating was comparable to that of a ten-colony method for samples containing resistant bacteria. However, this method classified significantly more samples as resistant to all eight antibiotics tested if the detection breakpoint was lowered to > or = 1% of the original colonies. Replica plating is an effective and practical tool for screening skin flora for resistance, also in samples with a low proportion of resistant strains.

  1. Facultative bacterial symbionts in aphids confer resistance to parasitic wasps

    PubMed Central

    Oliver, Kerry M.; Russell, Jacob A.; Moran, Nancy A.; Hunter, Martha S.

    2003-01-01

    Symbiotic relationships between animals and microorganisms are common in nature, yet the factors controlling the abundance and distributions of symbionts are mostly unknown. Aphids have an obligate association with the bacterium Buchnera aphidicola (the primary symbiont) that has been shown to contribute directly to aphid fitness. In addition, aphids sometimes harbor other vertically transmitted bacteria (secondary symbionts), for which few benefits of infection have been previously documented. We carried out experiments to determine the consequences of these facultative symbioses in Acyrthosiphon pisum (the pea aphid) for vulnerability of the aphid host to a hymenopteran parasitoid, Aphidius ervi, a major natural enemy in field populations. Our results show that, in a controlled genetic background, infection confers resistance to parasitoid attack by causing high mortality of developing parasitoid larvae. Compared with uninfected controls, experimentally infected aphids were as likely to be attacked by ovipositing parasitoids but less likely to support parasitoid development. This strong interaction between a symbiotic bacterium and a host natural enemy provides a mechanism for the persistence and spread of symbiotic bacteria. PMID:12563031

  2. The bacterial DNA repair protein Mfd confers resistance to the host nitrogen immune response

    PubMed Central

    Guillemet, Elisabeth; Leréec, Alain; Tran, Seav-Ly; Royer, Corinne; Barbosa, Isabelle; Sansonetti, Philippe; Lereclus, Didier; Ramarao, Nalini

    2016-01-01

    Production of reactive nitrogen species (NO) is a key step in the immune response following infections. NO induces lesions to bacterial DNA, thus limiting bacterial growth within hosts. Using two pathogenic bacteria, Bacillus cereus and Shigella flexneri, we show that the DNA-repair protein Mfd (Mutation-Frequency-Decline) is required for bacterial resistance to the host-NO-response. In both species, a mutant deficient for mfd does not survive to NO, produced in vitro or by phagocytic cells. In vivo, the ∆mfd mutant is avirulent and unable to survive the NO-stress. Moreover, NO induces DNA-double-strand-breaks and point mutations in the Δmfd mutant. In overall, these observations demonstrate that NO damages bacterial DNA and that Mfd is required to maintain bacterial genomic integrity. This unexpected discovery reveals that Mfd, a typical housekeeping gene, turns out to be a true virulence factor allowing survival and growth of the pathogen in its host, due to its capacity to protect the bacterium against NO, a key molecule of the innate immune defense. As Mfd is widely conserved in the bacterial kingdom, these data highlight a mechanism that may be used by a large spectrum of bacteria to overcome the host immune response and especially the mutagenic properties of NO. PMID:27435260

  3. Oscyp71Z2 involves diterpenoid phytoalexin biosynthesis that contributes to bacterial blight resistance in rice.

    PubMed

    Li, Wenqi; Shao, Min; Yang, Jie; Zhong, Weigong; Okada, Kazunori; Yamane, Hisakazu; Qian, Guoliang; Liu, Fengquan

    2013-06-01

    Bacterial blight is one of the most destructive rice diseases, which caused by Xoo, and results in yield losses, endangering worldwide food security. Diterpenoid phytoalexins, a type of antimicrobials produced in rice, are critical for resistance to fungal and bacterial pathogens. This article reports the characterization of the cytochrome P450 gene Oscyp71Z2, which belongs to the CYP71Z subfamily. Overexpression of Oscyp71Z2 in rice enhanced resistance to Xoo at the booting stage. The accumulation of phytoalexins was rapidly and strongly induced in Oscyp71Z2-overexpressing plants, and the transcript levels of genes related to the phytoalexin biosynthesis pathway were elevated. The H₂O₂ concentration in Oscyp71Z2-overexpressing plants was reduced in accordance with the increase in ROS-scavenging ability due to the induction of SOD as well as POD and CAT activation. We also showed that suppression of Oscyp71Z2 had no significantly effect on disease resistance to Xoo in rice. These results demonstrated that Oscyp71Z2 plays an important role in bacterial blight resistance by regulating the diterpenoid phytoalexin biosynthesis and H₂O₂ generation.

  4. Mathematical modelling of bacterial resistance to multiple antibiotics and immune system response.

    PubMed

    Daşbaşı, Bahatdin; Öztürk, İlhan

    2016-01-01

    Resistance of developed bacteria to antibiotic treatment is a very important issue, because introduction of any new antibiotic is after a little while followed by the formation of resistant bacterial isolates in the clinic. The significant increase in clinical resistance to antibiotics is a troubling situation especially in nosocomial infections, where already defenseless patients can be unsuccessful to respond to treatment, causing even greater health issue. Nosocomial infections can be identified as those happening within 2 days of hospital acceptance, 3 days of discharge or 1 month of an operation. They influence 1 out of 10 patients admitted to hospital. Annually, this outcomes in 5000 deaths only in UK with a cost to the National Health Service of a billion pounds. Despite these problems, antibiotic therapy is still the most common method used to treat bacterial infections. On the other hand, it is often mentioned that immune system plays a major role in the progress of infections. In this context, we proposed a mathematical model defining population dynamics of both the specific immune cells produced according to the properties of bacteria by host and the bacteria exposed to multiple antibiotics synchronically, presuming that resistance is gained through mutations due to exposure to antibiotic. Qualitative analysis found out infection-free equilibrium point and other equilibrium points where resistant bacteria and immune system cells exist, only resistant bacteria exists and sensitive bacteria, resistant bacteria and immune system cells exist. As a result of this analysis, our model highlights the fact that when an individual's immune system weakens, he/she suffers more from the bacterial infections which are believed to have been confined or terminated. Also, these results was supported by numerical simulations.

  5. Correlation models between environmental factors and bacterial resistance to antimony and copper.

    PubMed

    Shi, Zunji; Cao, Zhan; Qin, Dong; Zhu, Wentao; Wang, Qian; Li, Mingshun; Wang, Gejiao

    2013-01-01

    Antimony (Sb) and copper (Cu) are toxic heavy metals that are associated with a wide variety of minerals. Sb(III)-oxidizing bacteria that convert the toxic Sb(III) to the less toxic Sb(V) are potentially useful for environmental Sb bioremediation. A total of 125 culturable Sb(III)/Cu(II)-resistant bacteria from 11 different types of mining soils were isolated. Four strains identified as Arthrobacter, Acinetobacter and Janibacter exhibited notably high minimum inhibitory concentrations (MICs) for Sb(III) (>10 mM),making them the most highly Sb(III)-resistant bacteria to date. Thirty-six strains were able to oxidize Sb(III), including Pseudomonas-, Comamonas-, Acinetobacter-, Sphingopyxis-, Paracoccus- Aminobacter-, Arthrobacter-, Bacillus-, Janibacter- and Variovorax-like isolates. Canonical correspondence analysis (CCA) revealed that the soil concentrations of Sb and Cu were the most obvious environmental factors affecting the culturable bacterial population structures. Stepwise linear regression was used to create two predictive models for the correlation between soil characteristics and the bacterial Sb(III) or Cu(II) resistance. The concentrations of Sb and Cu in the soil was the significant factors affecting the bacterial Sb(III) resistance, whereas the concentrations of S and P in the soil greatly affected the bacterial Cu(II) resistance. The two stepwise linear regression models that we derived are as follows: MIC(Sb(III))=606.605+0.14533 x C(Sb)+0.4128 x C(Cu) and MIC((Cu)(II))=58.3844+0.02119 x C(S)+0.00199 x CP [where the MIC(Sb(III)) and MIC(Cu(II)) represent the average bacterial MIC for the metal of each soil (μM), and the C(Sb), C(Cu), C(S) and C(P) represent concentrations for Sb, Cu, S and P (mg/kg) in soil, respectively, p<0.01]. The stepwise linear regression models we developed suggest that metals as well as other soil physicochemical parameters can contribute to bacterial resistance to metals.

  6. Bacterial plasmid-mediated quinolone resistance genes in aquatic environments in China

    PubMed Central

    Yan, Lei; Liu, Dan; Wang, Xin-Hua; Wang, Yunkun; Zhang, Bo; Wang, Mingyu; Xu, Hai

    2017-01-01

    Emerging antimicrobial resistance is a major threat to human’s health in the 21st century. Understanding and combating this issue requires a full and unbiased assessment of the current status on the prevalence of antimicrobial resistance genes and their correlation with each other and bacterial groups. In aquatic environments that are known reservoirs for antimicrobial resistance genes, we were able to reach this goal on plasmid-mediated quinolone resistance (PMQR) genes that lead to resistance to quinolones and possibly also to the co-emergence of resistance to β-lactams. Novel findings were made that qepA and aac-(6′)-Ib genes that were previously regarded as similarly abundant with qnr genes are now dominant among PMQR genes in aquatic environments. Further statistical analysis suggested that the correlation between PMQR and β-lactam resistance genes in the environment is still weak, that the correlations between antimicrobial resistance genes could be weakened by sufficient wastewater treatment, and that the prevalence of PMQR has been implicated in environmental, pathogenic, predatory, anaerobic, and more importantly, human symbiotic bacteria. This work provides a comprehensive analysis of PMQR genes in aquatic environments in Jinan, China, and provides information with which combat with the antimicrobial resistance problem may be fought. PMID:28094345

  7. The drinking water treatment process as a potential source of affecting the bacterial antibiotic resistance.

    PubMed

    Bai, Xiaohui; Ma, Xiaolin; Xu, Fengming; Li, Jing; Zhang, Hang; Xiao, Xiang

    2015-11-15

    Two waterworks, with source water derived from the Huangpu or Yangtze River in Shanghai, were investigated, and the effluents were plate-screened for antibiotic-resistant bacteria (ARB) using five antibiotics: ampicillin (AMP), kanamycin (KAN), rifampicin (RFP), chloramphenicol (CM) and streptomycin (STR). The influence of water treatment procedures on the bacterial antibiotic resistance rate and the changes that bacteria underwent when exposed to the five antibiotics at concentration levels ranging from 1 to 100 μg/mL were studied. Multi-drug resistance was also analyzed using drug sensitivity tests. The results indicated that bacteria derived from water treatment plant effluent that used the Huangpu River rather than the Yangtze River as source water exhibited higher antibiotic resistance rates against AMP, STR, RFP and CM but lower antibiotic resistance rates against KAN. When the antibiotic concentration levels ranged from 1 to 10 μg/mL, the antibiotic resistance rates of the bacteria in the water increased as water treatment progressed. Biological activated carbon (BAC) filtration played a key role in increasing the antibiotic resistance rate of bacteria. Chloramine disinfection can enhance antibiotic resistance. Among the isolated ARB, 75% were resistant to multiple antibiotics. Ozone oxidation, BAC filtration and chloramine disinfection can greatly affect the relative abundance of bacteria in the community.

  8. Bacterial plasmid-mediated quinolone resistance genes in aquatic environments in China.

    PubMed

    Yan, Lei; Liu, Dan; Wang, Xin-Hua; Wang, Yunkun; Zhang, Bo; Wang, Mingyu; Xu, Hai

    2017-01-17

    Emerging antimicrobial resistance is a major threat to human's health in the 21(st) century. Understanding and combating this issue requires a full and unbiased assessment of the current status on the prevalence of antimicrobial resistance genes and their correlation with each other and bacterial groups. In aquatic environments that are known reservoirs for antimicrobial resistance genes, we were able to reach this goal on plasmid-mediated quinolone resistance (PMQR) genes that lead to resistance to quinolones and possibly also to the co-emergence of resistance to β-lactams. Novel findings were made that qepA and aac-(6')-Ib genes that were previously regarded as similarly abundant with qnr genes are now dominant among PMQR genes in aquatic environments. Further statistical analysis suggested that the correlation between PMQR and β-lactam resistance genes in the environment is still weak, that the correlations between antimicrobial resistance genes could be weakened by sufficient wastewater treatment, and that the prevalence of PMQR has been implicated in environmental, pathogenic, predatory, anaerobic, and more importantly, human symbiotic bacteria. This work provides a comprehensive analysis of PMQR genes in aquatic environments in Jinan, China, and provides information with which combat with the antimicrobial resistance problem may be fought.

  9. The "click" reaction involving metal azides, metal alkynes, or both: an exploration into multimetal structures.

    PubMed

    Casarrubios, Luis; de la Torre, María C; Sierra, Miguel A

    2013-03-11

    Cu(I) -catalyzed 1,3-cycloaddition of azides and alkynes (CuAAC) is one of the most powerful synthetic methodologies known. However, its use to prepare well-defined multimetallic structures is underdeveloped. Apart from the applications of this reaction to anchor different organometallic reagents to surfaces, polymers, and dendrimers, only isolated examples of CuAAC with metal-η(1) -alkyne and metal-azide complexes to prepare multimetal entities have been reported. This concept sketches the potential of these reactions not only to prepare "a la carte" multimetal 1,2,3-triazole derivatives, but also to discover new and unprecedented reactions.

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

    PubMed Central

    Cebrián, Guillermo; Mañas, Pilar; Condón, Santiago

    2016-01-01

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

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

    PubMed

    Cebrián, Guillermo; Mañas, Pilar; Condón, Santiago

    2016-01-01

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

  12. Epidemiology of urinary tract infections, bacterial species and resistances in primary care in France.

    PubMed

    Malmartel, A; Ghasarossian, C

    2016-03-01

    General practitioners often have to manage urinary tract infections (UTI) with probabilistic treatments, although bacterial resistances are increasing. Therefore, the French Society of Infectious Diseases published new guidelines in 2014. The aim of this study was to investigate the bacterial epidemiology of UTI in the general population in primary care and analyse risk factors for Escherichia coli resistance to antibiotics. A cross-sectional study was conducted in 12 ambulatory laboratories. Patients over 18 years of age coming for urinalysis were included. Risk factors for UTI were collected using a questionnaire and the laboratory records. Bacteria meeting criteria for UTI were analysed. A positive urinalysis was found in 1119 patients, corresponding to 1125 bacterial isolates. The bacterial species were: E. coli (73 %), Enterococcus spp. (7 %), Klebsiella spp. (6 %), Proteus spp. (4 %), Staphylococcus spp. (3 %) and Pseudomonas spp. (2 %). Regardless of the bacteria, the most common resistance was that to co-trimoxazole: 27 % (95 % confidence interval [CI] = [0.24; 0.30]), followed by ofloxacin resistance: 16 % [0.14; 0.18]. Escherichia coli resistances to co-trimoxazole, ofloxacin, cefixime, nitrofurantoin and fosfomycin were, respectively, 25.5 % [0.23; 0.28], 17 % [0.14; 0.20], 5.6 % [0.04; 0.07], 2.2 % [0.01; 0.03] and 1.2 % [0.005; 0.02]. Independent risk factors for E. coli resistance to ofloxacin were age over 85 years (odds ratio [OR] = 3.08; [1.61; 5.87]) and a history of UTI in the last 6 months (OR = 2.34; [1.54; 3.52]). Our findings support the guidelines recommending fluoroquinolone sparing. The scarcity of E. coli resistance to fosfomycin justifies its use as a first-line treatment in acute cystitis. These results should be reassessed in a few years to identify changes in the bacterial epidemiology of UTI.

  13. Making Silicone Rubber Highly Resistant to Bacterial Attachment Using Thiol-ene Grafting

    PubMed Central

    2016-01-01

    Biomedical devices are indispensable in modern medicine yet offer surfaces that promote bacterial attachment and biofilm formation, resulting in acute and chronic healthcare-associated infections. We have developed a simple method to graft acrylates to silicone rubber, polydimethylsiloxane (PDMS), a commonly used device material that is often colonized by bacteria. We demonstrate a novel method whereby nontoxic bacteria attachment-resistant polymers can be readily grafted from and grafted to the surface using thiol-ene chemistry, substantially reducing bacterial colonization. With use of this approach, bacterial biofilm coverage can be reduced by 99% compared with standard PDMS in an in vitro assay. This grafting approach offers significant advantages over commonly used physisorbed coatings, especially in areas of high shear or mechanical stress. Furthermore, the approach is versatile such that the grafted material properties can be tailored for the desired final application. PMID:27775316

  14. Evaluation of radiation resistance of the bacterial contaminants from femoral heads processed for allogeneic transplantation

    NASA Astrophysics Data System (ADS)

    Singh, Rita; Singh, Durgeshwer

    2009-09-01

    Femoral heads excised during surgery were obtained from patients who had a fractured neck of the femur and were processed as bone allograft. The bacterial contaminants were isolated from femoral heads at different stages of processing and identified based on morphological characteristics and biochemical tests. Bacterial contaminants on bone were mainly Gram-positive bacilli and cocci (58.3%). Twenty-four isolates from bone samples were screened for resistance to radiation. The D10 values for Gram-negative bacteria isolated from femoral heads ranged from 0.17 to 0.65 kGy. Higher D10 values 0.56-1.04 kGy were observed for Gram-positive bacterial isolates.

  15. MinION nanopore sequencing identifies the position and structure of a bacterial antibiotic resistance island.

    PubMed

    Ashton, Philip M; Nair, Satheesh; Dallman, Tim; Rubino, Salvatore; Rabsch, Wolfgang; Mwaigwisya, Solomon; Wain, John; O'Grady, Justin

    2015-03-01

    Short-read, high-throughput sequencing technology cannot identify the chromosomal position of repetitive insertion sequences that typically flank horizontally acquired genes such as bacterial virulence genes and antibiotic resistance genes. The MinION nanopore sequencer can produce long sequencing reads on a device similar in size to a USB memory stick. Here we apply a MinION sequencer to resolve the structure and chromosomal insertion site of a composite antibiotic resistance island in Salmonella Typhi Haplotype 58. Nanopore sequencing data from a single 18-h run was used to create a scaffold for an assembly generated from short-read Illumina data. Our results demonstrate the potential of the MinION device in clinical laboratories to fully characterize the epidemic spread of bacterial pathogens.

  16. Arabidopsis EF-Tu receptor enhances bacterial disease resistance in transgenic wheat.

    PubMed

    Schoonbeek, Henk-Jan; Wang, Hsi-Hua; Stefanato, Francesca L; Craze, Melanie; Bowden, Sarah; Wallington, Emma; Zipfel, Cyril; Ridout, Christopher J

    2015-04-01

    Perception of pathogen (or microbe)-associated molecular patterns (PAMPs/MAMPs) by pattern recognition receptors (PRRs) is a key component of plant innate immunity. The Arabidopsis PRR EF-Tu receptor (EFR) recognizes the bacterial PAMP elongation factor Tu (EF-Tu) and its derived peptide elf18. Previous work revealed that transgenic expression of AtEFR in Solanaceae confers elf18 responsiveness and broad-spectrum bacterial disease resistance. In this study, we developed a set of bioassays to study the activation of PAMP-triggered immunity (PTI) in wheat. We generated transgenic wheat (Triticum aestivum) plants expressing AtEFR driven by the constitutive rice actin promoter and tested their response to elf18. We show that transgenic expression of AtEFR in wheat confers recognition of elf18, as measured by the induction of immune marker genes and callose deposition. When challenged with the cereal bacterial pathogen Pseudomonas syringae pv. oryzae, transgenic EFR wheat lines had reduced lesion size and bacterial multiplication. These results demonstrate that AtEFR can be transferred successfully from dicot to monocot species, further revealing that immune signalling pathways are conserved across these distant phyla. As novel PRRs are identified, their transfer between plant families represents a useful strategy for enhancing resistance to pathogens in crops.

  17. Strategies to overcome the action of aminoglycoside-modifying enzymes for treating resistant bacterial infections

    PubMed Central

    Labby, Kristin J; Garneau-Tsodikova, Sylvie

    2013-01-01

    Shortly after the discovery of the first antibiotics, bacterial resistance began to emerge. Many mechanisms give rise to resistance; the most prevalent mechanism of resistance to the aminoglycoside (AG) family of antibiotics is the action of aminoglycoside-modifying enzymes (AMEs). Since the identification of these modifying enzymes, many efforts have been put forth to prevent their damaging alterations of AGs. These diverse strategies are discussed within this review, including: creating new AGs that are unaffected by AMEs; developing inhibitors of AMEs to be co-delivered with AGs; or regulating AME expression. Modern high-throughput methods as well as drug combinations and repurposing are highlighted as recent drug-discovery efforts towards fighting the increasing antibiotic resistance crisis. PMID:23859208

  18. On the in vivo significance of bacterial resistance to antimicrobial peptides

    PubMed Central

    Bauer, Margaret E.; Shafer, William M.

    2015-01-01

    Antimicrobial peptides (AMPs) are at the front-line of host defense during infection and play critical roles both in reducing the microbial load early during infection and in linking innate to adaptive immunity. However, successful pathogens have developed mechanisms to resist AMPs. Although considerable progress has been made in elucidating AMP-resistance mechanisms of pathogenic bacteria in vitro, less is known regarding the in vivo significance of such resistance. Nevertheless, progress has been made in this area, largely by using murine models and, in two instances, human models of infection. Herein, we review progress on the use of in vivo infection models in AMP research and discuss the AMP resistance mechanisms that have been established by in vivo studies to contribute to microbial infection. We posit that in vivo infection models are essential tools for investigators to understand the significance to pathogenesis of genetic changes that impact levels of bacterial susceptibility to AMPs. PMID:25701234

  19. Mapping EST-derived SSRs and ESTs involved in resistance to bacterial blight in Manihot esculenta.

    PubMed

    López, Camilo E; Quesada-Ocampo, Lina M; Bohórquez, Adriana; Duque, Myriam Cristina; Vargas, Jaime; Tohme, Joe; Verdier, Valérie

    2007-12-01

    Cassava (Manihot esculenta Crantz) is a major root crop widely grown in the tropics. Cassava bacterial blight, caused by Xanthomonas axonopodis pv. manihotis (Xam), is an important disease in Latin America and Africa resulting in significant losses. The preferred control method is the use of resistant genotypes. Mapping expressed sequence tags (ESTs) and determining their co-localization with quantitative trait loci (QTLs) may give additional evidence of the role of the corresponding genes in resistance or defense. Twenty-one EST-derived simple sequence repeats (SSRs) were mapped in 16 linkage groups. ESTs showing similarities with candidate resistance genes or defense genes were also mapped using strategies such as restriction fragment length polymorphisms, cleaved amplified polymorphic sequences, and allele-specific primers. In total, 10 defense-related genes and 2 bacterial artificial chromosomes (BACs) containing resistance gene candidates (RGCs) were mapped in 11 linkage groups. Two new QTLs associated with resistance to Xam strains CIO121 and CIO151 were detected in linkage groups A and U, respectively. The QTL in linkage group U explained 61.6% of the phenotypic variance and was associated with an RGC-containing BAC. No correlation was found between the new EST-derived SSRs or other mapped ESTs and the new or previously reported QTLs.

  20. High Prevalence of Antimicrobial Resistance Among Common Bacterial Isolates in a Tertiary Healthcare Facility in Rwanda

    PubMed Central

    Ntirenganya, Cyprien; Manzi, Olivier; Muvunyi, Claude Mambo; Ogbuagu, Onyema

    2015-01-01

    Antimicrobial resistance (AMR) is a serious public health threat in both developed and developing countries. Many developing countries, including Rwanda, lack adequate surveillance systems, and therefore, the prevalence of AMR is not well-known. We conducted a prospective observational study to assess the prevalence of AMR among common bacterial isolates from clinical specimens obtained from patients on the medical wards of Kigali University Teaching Hospital (KUTH). We evaluated the antibiotic sensitivity patterns of bacterial pathogens cultured from urine, blood, sputum, and wound swab specimens obtained over a 6-month period (July 1 to December 30, 2013). There were 154 positive cultures from specimens obtained from 141 unique patients over the study period. Urine, blood, wound swab, and sputum cultures comprised 55.2%, 25.3%, 16.2%, and 3.3% of the total specimens evaluated; 31.4% and 58.7% of Escherichia coli and Klebsiella isolates, respectively, were resistant to at least one of the third generation cephalosporins. Eight percent of E. coli isolates were resistant to imipenem; 82% and 6% of Staphylococcus aureus strains were oxacillin- and vancomycin-resistant respectively. Antimicrobial resistance rates are high in Rwanda and pose a serious therapeutic challenge to the management of common infections. PMID:25646259

  1. On the in vivo significance of bacterial resistance to antimicrobial peptides.

    PubMed

    Bauer, Margaret E; Shafer, William M

    2015-11-01

    Antimicrobial peptides (AMPs) are at the front-line of host defense during infection and play critical roles both in reducing the microbial load early during infection and in linking innate to adaptive immunity. However, successful pathogens have developed mechanisms to resist AMPs. Although considerable progress has been made in elucidating AMP-resistance mechanisms of pathogenic bacteria in vitro, less is known regarding the in vivo significance of such resistance. Nevertheless, progress has been made in this area, largely by using murine models and, in two instances, human models of infection. Herein, we review progress on the use of in vivo infection models in AMP research and discuss the AMP resistance mechanisms that have been established by in vivo studies to contribute to microbial infection. We posit that in vivo infection models are essential tools for investigators to understand the significance to pathogenesis of genetic changes that impact levels of bacterial susceptibility to AMPs. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.

  2. Antibiotic discovery: combatting bacterial resistance in cells and in biofilm communities.

    PubMed

    Penesyan, Anahit; Gillings, Michael; Paulsen, Ian T

    2015-03-24

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

  3. Incorporation of Bacterial Blight Resistance Genes Into Lowland Rice Cultivar Through Marker-Assisted Backcross Breeding.

    PubMed

    Pradhan, Sharat Kumar; Nayak, Deepak Kumar; Pandit, Elssa; Behera, Lambodar; Anandan, Annamalai; Mukherjee, Arup Kumar; Lenka, Srikanta; Barik, Durga Prasad

    2016-07-01

    Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is a major disease of rice in many rice growing countries. Pyramided lines carrying two BB resistance gene combinations (Xa21+xa13 and Xa21+xa5) were developed in a lowland cultivar Jalmagna background through backcross breeding by integrating molecular markers. In each backcross generation, markers closely linked to the disease resistance genes were used to select plants possessing the target genes. Background selection was continued in those plants carrying resistant genes until BC(3) generation. Plants having the maximum contribution from the recurrent parent genome were selected in each generation and hybridized with the recipient parent. The BB-pyramided line having the maximum recipient parent genome recovery of 95% was selected among BC3F1 plants and selfed to isolate homozygous BC(3)F(2) plants with different combinations of BB resistance genes. Twenty pyramided lines with two resistance gene combinations exhibited high levels of tolerance against the BB pathogen. In order to confirm the resistance, the pyramided lines were inoculated with different X. oryzae pv. oryzae strains of Odisha for bioassay. The genotypes with combination of two BB resistance genes conferred high levels of resistance to the predominant X. oryzae pv. oryzae isolates prevalent in the region. The pyramided lines showed similarity with the recipient parent with respect to major agro-morphologic traits.

  4. Emerging issues in gram-negative bacterial resistance: an update for the practicing clinician.

    PubMed

    Vasoo, Shawn; Barreto, Jason N; Tosh, Pritish K

    2015-03-01

    The rapid and global spread of antimicrobial-resistant organisms in recent years has been unprecedented. Although resistant gram-positive infections have been concerning to clinicians, the increasing incidence of antibiotic-resistant gram-negative infections has become the most pressing issue in bacterial resistance. Indiscriminate antimicrobial use in humans and animals coupled with increased global connectivity facilitated the transmission of gram-negative infections harboring extended-spectrum β-lactamases in the 1990s. Carbapenemase-producing Enterobacteriaceae, such as those containing Klebsiella pneumoniae carbapenemases and New Delhi metallo-β-lactamases, have been the latest scourge since the late 1990s to 2000s. Besides β-lactam resistance, these gram-negative infections are often resistant to multiple drug classes, including fluoroquinolones, which are commonly used to treat community-onset infections. In certain geographic locales, these pathogens, which have been typically associated with health care-associated infections, are disseminating into the community, posing a significant dilemma for clinicians treating community-onset infections. In this Concise Review, we summarize emerging trends in antimicrobial resistance. We also review the current knowledge on the detection, treatment, and prevention of infection with these organisms, with a focus on the carbapenemase-producing gram-negative bacilli. Finally, we discuss emerging therapies and areas that need further research and effort to stem the spread of antimicrobial resistance.

  5. Cockroaches as a Source of High Bacterial Pathogens with Multidrug Resistant Strains in Gondar Town, Ethiopia

    PubMed Central

    Huruy, Kahsay; Muluye, Dagnachew; Feleke, Tigist; G/Silassie, Fisha; Ayalew, Getenet; Nagappan, Raja

    2016-01-01

    Background. Cockroaches are source of bacterial infections and this study was aimed to assess bacterial isolates and their antimicrobial profiles from cockroaches in Gondar town, Ethiopia. Methods. A total of 60 cockroaches were collected from March 1 to May 30, 2014, in Gondar town. Bacterial species were isolated from external and internal parts of cockroaches. Disk diffusion method was used to determine antibiotic susceptibility patterns. Data were entered and analyzed by using SPSS version 20; P values <0.005 were considered as statistically significant. Results. Of 181 identified bacteria species, 110 (60.8%) and 71 (39.2%) were identified from external and internal parts of cockroaches, respectively. Klebsiella pneumoniae 32 (17.7%), Escherichia coli 29 (16%), and Citrobacter spp. 27 (15%) were the predominant isolates. High resistance rate was observed to cotrimoxazole, 60 (33.1%), and least resistance rate was noted to ciprofloxacin, 2 (1.1%). Additionally, 116 (64.1%) of the isolates were MDR strains; Salmonella spp. were the leading MDR isolates (100%) followed by Enterobacter (90.5%) and Shigella spp. (76.9%). Conclusion. Cockroaches are the potential source of bacteria pathogens with multidrug resistant strains and hence effective preventive and control measures are required to minimize cockroach related infections. PMID:27340653

  6. Cockroaches as a Source of High Bacterial Pathogens with Multidrug Resistant Strains in Gondar Town, Ethiopia.

    PubMed

    Moges, Feleke; Eshetie, Setegn; Endris, Mengistu; Huruy, Kahsay; Muluye, Dagnachew; Feleke, Tigist; G/Silassie, Fisha; Ayalew, Getenet; Nagappan, Raja

    2016-01-01

    Background. Cockroaches are source of bacterial infections and this study was aimed to assess bacterial isolates and their antimicrobial profiles from cockroaches in Gondar town, Ethiopia. Methods. A total of 60 cockroaches were collected from March 1 to May 30, 2014, in Gondar town. Bacterial species were isolated from external and internal parts of cockroaches. Disk diffusion method was used to determine antibiotic susceptibility patterns. Data were entered and analyzed by using SPSS version 20; P values <0.005 were considered as statistically significant. Results. Of 181 identified bacteria species, 110 (60.8%) and 71 (39.2%) were identified from external and internal parts of cockroaches, respectively. Klebsiella pneumoniae 32 (17.7%), Escherichia coli 29 (16%), and Citrobacter spp. 27 (15%) were the predominant isolates. High resistance rate was observed to cotrimoxazole, 60 (33.1%), and least resistance rate was noted to ciprofloxacin, 2 (1.1%). Additionally, 116 (64.1%) of the isolates were MDR strains; Salmonella spp. were the leading MDR isolates (100%) followed by Enterobacter (90.5%) and Shigella spp. (76.9%). Conclusion. Cockroaches are the potential source of bacteria pathogens with multidrug resistant strains and hence effective preventive and control measures are required to minimize cockroach related infections.

  7. Bacterial Communities Differ among Drosophila melanogaster Populations and Affect Host Resistance against Parasitoids

    PubMed Central

    Dini-Andreote, Francisco; Falcao Salles, Joana

    2016-01-01

    In Drosophila, diet is considered a prominent factor shaping the associated bacterial community. However, the host population background (e.g. genotype, geographical origin and founder effects) is a factor that may also exert a significant influence and is often overlooked. To test for population background effects, we characterized the bacterial communities in larvae of six genetically differentiated and geographically distant D. melanogaster lines collected from natural populations across Europe. The diet for these six lines had been identical for ca. 50 generations, thus any differences in the composition of the microbiome originates from the host populations. We also investigated whether induced shifts in the microbiome—in this case by controlled antibiotic administration—alters the hosts’ resistance to parasitism. Our data revealed a clear signature of population background on the diversity and composition of D. melanogaster microbiome that differed across lines, even after hosts had been maintained at the same diet and laboratory conditions for over 4 years. In particular, the number of bacterial OTUs per line ranged from 8 to 39 OTUs. Each line harboured 2 to 28 unique OTUs, and OTUs that were highly abundant in some lines were entirely missing in others. Moreover, we found that the response to antibiotic treatment differed among the lines and significantly altered the host resistance to the parasitoid Asobara tabida in one of the six lines. Wolbachia, a widespread intracellular endosymbiont associated with parasitoid resistance, was lacking in this line, suggesting that other components of the Drosophila microbiome caused a change in host resistance. Collectively, our results revealed that lines that originate from different population backgrounds show significant differences in the established Drosophila microbiome, outpacing the long-term effect of diet. Perturbations on these naturally assembled microbiomes to some degree influenced the hosts

  8. RESULTS OF THE SEPTEMBER 1997 DOE/EPA DEMONSTRATION OF MULTIMETAL CONTINUOUS EMISSION MONITORING TECHNOLOGIES

    EPA Science Inventory

    In September 1997, the U.S. Department of Energy (DOE) and U.S. Environmental Protection Agency (EPA) co-sponsored a demonstration of several multimetal continuous emission monitos (CEMs). The demonstration, performed at the EPA National Risk Management Research Laboratory, Air P...

  9. Performance testing of multi-metal continuous emissions monitors. Appendix Volume 2

    SciTech Connect

    Haas, W.J. Jr.; French, N.B.; Brown, C.H.; Burns, D.B.; Lemieux, P.M.; Ryan, J.V.; Priebe, S.J.; Waterland, L.R.

    1997-11-17

    This report contains appendices to the study of three prototype multi-metals continuous emission monitors (CEMs). The appendices are: Diagnostic Instrumentation and Analytical Laboratory daily logbook pages and CEM data; Navy/Thermo Jarrell Ash Corp. daily logbook pages and CEM data; Sandia National Laboratories daily logbook pages and CEM data; Measurement data from Insitec particle counter, sizers, velocimeter.

  10. Molecular determinants of bacterial sensitivity and resistance to mammalian Group IIA phospholipase A2.

    PubMed

    Weiss, Jerrold P

    2015-11-01

    Group IIA secretory phospholipase A2 (sPLA(2)-IIA) of mammalian species is unique among the many structurally and functionally related mammalian sPLA(2) in their high net positive charge and potent (nM) antibacterial activity. Toward the Gram-positive bacteria tested thus far, the global cationic properties of sPLA(2)-IIA are necessary for optimal binding to intact bacteria and penetration of the multi-layered thick cell wall, but not for the degradation of membrane phospholipids that is essential for bacterial killing. Various Gram-positive bacterial species can differ as much as 1000-fold in sPLA(2)-IIA sensitivity despite similar intrinsic enzymatic activity of sPLA(2)-IIA toward the membrane phospholipids of various bacteria. d-alanylation of wall- and lipo-teichoic acids in Staphylococcus aureus and sortase function in Streptococcus pyogenes increase bacterial resistance to sPLA(2)-IIA by up to 100-fold apparently by affecting translocation of bound sPLA(2)-IIA to the cell membrane. Action of the sPLA(2)-IIA and other related sPLA(2) against Gram-negative bacteria is more dependent on cationic properties of the enzyme near the amino-terminus of the protein and collaboration with other host defense proteins that produce alterations of the unique Gram-negative bacterial outer membrane that normally represents a barrier to sPLA(2)-IIA action. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.

  11. Reduction of rainbow trout spleen size by splenectomy does not alter resistance against bacterial cold water disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In lower vertebrates, the contribution of the spleen to anti-bacterial immunity is poorly understood. Researchers have previously reported a phenotypic and genetic correlation between resistance to Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD) and spleen so...

  12. Major Histocompatibility Complex Based Resistance to a Common Bacterial Pathogen of Amphibians

    PubMed Central

    Barribeau, Seth M.; Villinger, Jandouwe; Waldman, Bruce

    2008-01-01

    Given their well-developed systems of innate and adaptive immunity, global population declines of amphibians are particularly perplexing. To investigate the role of the major histocompatibilty complex (MHC) in conferring pathogen resistance, we challenged Xenopus laevis tadpoles bearing different combinations of four MHC haplotypes (f, g, j, and r) with the bacterial pathogen Aeromonas hydrophila in two experiments. In the first, we exposed ff, fg, gg, gj, and jj tadpoles, obtained from breeding MHC homozygous parents, to one of three doses of A. hydrophila or heat-killed bacteria as a control. In the second, we exposed ff, fg, fr, gg, rg, and rr tadpoles, obtained from breeding MHC heterozygous parents and subsequently genotyped by PCR, to A. hydrophila, heat-killed bacteria or media alone as controls. We thereby determined whether the same patterns of MHC resistance emerged within as among families, independent of non-MHC heritable differences. Tadpoles with r or g MHC haplotypes were more likely to die than were those with f or j haplotypes. Growth rates varied among MHC types, independent of exposure dose. Heterozygous individuals with both susceptible and resistant haplotypes were intermediate to either homozygous genotype in both size and survival. The effect of the MHC on growth and survival was consistent between experiments and across families. MHC alleles differentially confer resistance to, or tolerance of, the bacterial pathogen, which affects tadpoles' growth and survival. PMID:18629002

  13. Major histocompatibility complex based resistance to a common bacterial pathogen of amphibians.

    PubMed

    Barribeau, Seth M; Villinger, Jandouwe; Waldman, Bruce

    2008-07-16

    Given their well-developed systems of innate and adaptive immunity, global population declines of amphibians are particularly perplexing. To investigate the role of the major histocompatibility complex (MHC) in conferring pathogen resistance, we challenged Xenopus laevis tadpoles bearing different combinations of four MHC haplotypes (f, g, j, and r) with the bacterial pathogen Aeromonas hydrophila in two experiments. In the first, we exposed ff, fg, gg, gj, and jj tadpoles, obtained from breeding MHC homozygous parents, to one of three doses of A. hydrophila or heat-killed bacteria as a control. In the second, we exposed ff, fg, fr, gg, rg, and rr tadpoles, obtained from breeding MHC heterozygous parents and subsequently genotyped by PCR, to A. hydrophila, heat-killed bacteria or media alone as controls. We thereby determined whether the same patterns of MHC resistance emerged within as among families, independent of non-MHC heritable differences. Tadpoles with r or g MHC haplotypes were more likely to die than were those with f or j haplotypes. Growth rates varied among MHC types, independent of exposure dose. Heterozygous individuals with both susceptible and resistant haplotypes were intermediate to either homozygous genotype in both size and survival. The effect of the MHC on growth and survival was consistent between experiments and across families. MHC alleles differentially confer resistance to, or tolerance of, the bacterial pathogen, which affects tadpoles' growth and survival.

  14. Plastic phenotypic resistance to predation by Bdellovibrio and like organisms in bacterial prey.

    PubMed

    Shemesh, Yair; Jurkevitch, Edouard

    2004-01-01

    Predation at the lowest trophic level, i.e. between bacteria, is poorly understood, hindering efforts to assess its impact on the structure of bacterial communities. The interaction of Bdellovibrio and Bacteriovorax (Bdellovibrio and like organisms, BLOs), a group of obligate, ubiquitous predatory bacteria, with their Gram-negative bacterial prey results in the multiplication of the predator and in the lysis, but not in the eradication, of the prey. We show that the residual, surviving populations of prey cells exposed to predation stress differ from the populations before exposure, as they exhibit increased resistance to predation. This resistance was demonstrated in a number of Gram-negative prey. Moreover, predation resistance is not specific for the BLO strain experienced by the prey. The phenomenon does not stem from a mutation but is a plastic response associated with a phenotypic change, and it disappears upon removal of the predator. As resistance to predation is not total, this mechanism can ensure survival of both predator and prey.

  15. A retrospective analysis of skin bacterial colonisation, susceptibility and resistance in atopic dermatitis and impetigo patients.

    PubMed

    Salah, Louai A; Faergemann, Jan

    2015-05-01

    Atopic dermatitis (AD) and impetigo are skin conditions where bacterial colonisation and infection, especially with Staphylococcus aureus play an important role. We compared skin bacterial population, resistance patterns and choice of antimicrobial agents in patients diagnosed with AD and impetigo during 2005 and 2011 in our department. Number of positive cultures in the AD group were 40 and 53 in 2005 and 2011, with S. aureus found in 97.5% and 100%, respectively. Differences in resistance were marginal. In impetigo, S. aureus was found in all 70 patients in 2005 and all 40 patients in 2011. Antibiotic resistance to specifically fusidic acid was more common in 2005 impetigo patients (22.8%) versus 2011 (5%) (p = 0.078). The most commonly used oral antimicrobial was cefadroxil (in 57.5% and 52.8% of AD and 58.6% and 35% of impetigo patients in 2005 and 2011, respectively). Our observations confirm the high prevalence of S. aureus in both diseases and, interestingly, show a declining resistance trend in impetigo.

  16. Structural Studies of Bacterial Enzymes and their Relation to Antibiotic Resistance Mechanisms - Final Paper

    SciTech Connect

    Maltz, Lauren

    2015-08-27

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

  17. Exposure of juvenile Leghorn chickens to lead acetate enhances antibiotic resistance in enteric bacterial flora.

    PubMed

    Nisanian, M; Holladay, S D; Karpuzoglu, E; Kerr, R P; Williams, S M; Stabler, L; McArthur, J Vaun; Tuckfield, R Cary; Gogal, R M

    2014-04-01

    Heavy metals have been implicated for their ability to increase antibiotic resistance in bacteria collected from polluted waters, independent of antibiotic exposure. Specific-pathogen-free Leghorn chickens were therefore given Pb acetate in the drinking water to expose the enteric bacteria to Pb and to determine if antibiotic resistance changed in these bacteria. Concentrations of Pb used were 0.0, 0.01, 0.1, 1.0, or 10.0 mM; birds given the highest 2 concentrations showed signs of moribundity and dehydration and were removed from the study. Vent culture samples were collected for bacterial cultures on d 0 before Pb exposure, d 7 and 14, and then birds were euthanized by CO2 gas for necropsy on d 14, at which time intestinal contents were also collected for bacterial cultures. Fecal swabs but not intestinal samples from Pb-exposed birds contained isolates that had significantly elevated antibiotic resistance. Some of the isolates contained bacteria that were resistant to up to 20 antibiotics. These results suggest the need for repeated studies in chickens infected with zoonotic pathogens.

  18. Constitutive presence of antibiotic resistance genes within the bacterial community of a large subalpine lake.

    PubMed

    Di Cesare, Andrea; Eckert, Ester M; Teruggi, Alessia; Fontaneto, Diego; Bertoni, Roberto; Callieri, Cristiana; Corno, Gianluca

    2015-08-01

    The fate of antibiotic resistance genes (ARGs) in environmental microbial communities is of primary concern as prodromal of a potential transfer to pathogenic bacteria. Although of diverse origin, the persistence of ARGs in aquatic environments is highly influenced by anthropic activities, allowing potential control actions in well-studied environments. However, knowledge of abundance and space-time distribution of ARGs in ecosystems is still scarce. Using quantitative real-time PCR, we investigated the presence and the abundance of twelve ARGs (against tetracyclines, β-lactams, aminoglycosides, quinolones and sulphonamides) at different sampling sites, depths and seasons, in Lake Maggiore, a large subalpine lake, and in the area of its watershed. We then evaluated the correlation between each ARG and a number of ecological parameters in the water column in the deepest part of the lake. Our results suggest the constitutive presence of at least four ARGs within the bacterial community with a high proportion of bacteria potentially resistant to tetracyclines and sulphonamides. The presence of these ARGs was independent of the total bacterial density and temperature. The dynamics of tet(A) and sulII genes were, however, positively correlated with dissolved oxygen and negatively to chlorophyll a, suggesting that the resistant microbes inhabit specific niches. These observations indicate that the lake is a reservoir of antibiotic resistances, highlighting the need of a deeper understanding of the sources of ARGs and the factors allowing their persistence in waters.

  19. Antibiotic usage in animals: impact on bacterial resistance and public health.

    PubMed

    van den Bogaard, A E; Stobberingh, E E

    1999-10-01

    Antibiotic use whether for therapy or prevention of bacterial diseases, or as performance enhancers will result in antibiotic resistant micro-organisms, not only among pathogens but also among bacteria of the endogenous microflora of animals. The extent to which antibiotic use in animals will contribute to the antibiotic resistance in humans is still under much debate. In addition to the veterinary use of antibiotics, the use of these agents as antimicrobial growth promoters (AGP) greatly influences the prevalence of resistance in animal bacteria and a poses risk factor for the emergence of antibiotic resistance in human pathogens. Antibiotic resistant bacteria such as Escherichia coli, Salmonella spp., Campylobacter spp. and enterococci from animals can colonise or infect the human population via contact (occupational exposure) or via the food chain. Moreover, resistance genes can be transferred from bacteria of animals to human pathogens in the intestinal flora of humans. In humans, the control of resistance is based on hygienic measures: prevention of cross contamination and a decrease in the usage of antibiotics. In food animals housed closely together, hygienic measures, such as prevention of oral-faecal contact, are not feasible. Therefore, diminishing the need for antibiotics is the only possible way of controlling resistance in large groups of animals. This can be achieved by improvement of animal husbandry systems, feed composition and eradication of or vaccination against infectious diseases. Moreover, abolishing the use of antibiotics as feed additives for growth promotion in animals bred as a food source for humans would decrease the use of antibiotics in animals on a worldwide scale by nearly 50%. This would not only diminish the public health risk of dissemination of resistant bacteria or resistant genes from animals to humans, but would also be of major importance in maintaining the efficacy of antibiotics in veterinary medicine.

  20. Overexpression of BSR1 confers broad-spectrum resistance against two bacterial diseases and two major fungal diseases in rice

    PubMed Central

    Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki

    2016-01-01

    Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen. PMID:27436950

  1. Overexpression of BSR1 confers broad-spectrum resistance against two bacterial diseases and two major fungal diseases in rice.

    PubMed

    Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki

    2016-06-01

    Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen.

  2. A conservative region of the mercuric reductase gene (mera) as a molecular marker of bacterial mercury resistance

    PubMed Central

    Sotero-Martins, Adriana; de Jesus, Michele Silva; Lacerda, Michele; Moreira, Josino Costa; Filgueiras, Ana Luzia Lauria; Barrocas, Paulo Rubens Guimarães

    2008-01-01

    The most common bacterial mercury resistance mechanism is based on the reduction of Hg(II) to Hg0, which is dependent of the mercuric reductase enzyme (MerA) activity. The use of a 431 bp fragment of a conservative region of the mercuric reductase (merA) gene was applied as a molecular marker of this mechanism, allowing the identification of mercury resistant bacterial strains. PMID:24031221

  3. QTL mapping for bacterial wilt resistance in peanut (Arachis hypogaea L.).

    PubMed

    Zhao, Yongli; Zhang, Chong; Chen, Hua; Yuan, Mei; Nipper, Rick; Prakash, C S; Zhuang, Weijian; He, Guohao

    Bacterial wilt (BW) caused by Ralstonia solanacearum is a serious, global, disease of peanut (Arachis hypogaea L.), but it is especially destructive in China. Identification of DNA markers linked to the resistance to this disease will help peanut breeders efficiently develop resistant cultivars through molecular breeding. A F2 population, from a cross between disease-resistant and disease-susceptible cultivars, was used to detect quantitative trait loci (QTL) associated with the resistance to this disease in the cultivated peanut. Genome-wide SNPs were identified from restriction-site-associated DNA sequencing tags using next-generation DNA sequencing technology. SNPs linked to disease resistance were determined in two bulks of 30 resistant and 30 susceptible plants along with two parental plants using bulk segregant analysis. Polymorphic SSR and SNP markers were utilized for construction of a linkage map and for performing the QTL analysis, and a moderately dense linkage map was constructed in the F2 population. Two QTL (qBW-1 and qBW-2) detected for resistance to BW disease were located in the linkage groups LG1 and LG10 and account for 21 and 12 % of the bacterial wilt phenotypic variance. To confirm these QTL, the F8 RIL population with 223 plants was utilized for genotyping and phenotyping plants by year and location as compared to the F2 population. The QTL qBW-1 was consistent in the location of LG1 in the F8 population though the QTL qBW-2 could not be clarified due to fewer markers used and mapped in LG10. The QTL qBW-1, including four linked SNP markers and one SSR marker within 14.4-cM interval in the F8, was closely related to a disease resistance gene homolog and was considered as a candidate gene for resistance to BW. QTL identified in this study would be useful to conduct marker-assisted selection and may permit cloning of resistance genes. Our study shows that bulk segregant analysis of genome-wide SNPs is a useful approach to expedite the

  4. Decision tools for bacterial blight resistance gene deployment in rice-based agricultural ecosystems

    PubMed Central

    Dossa, Gerbert S.; Sparks, Adam; Cruz, Casiana Vera; Oliva, Ricardo

    2015-01-01

    Attempting to achieve long-lasting and stable resistance using uniformly deployed rice varieties is not a sustainable approach. The real situation appears to be much more complex and dynamic, one in which pathogens quickly adapt to resistant varieties. To prevent disease epidemics, deployment should be customized and this decision will require interdisciplinary actions. This perspective article aims to highlight the current progress on disease resistance deployment to control bacterial blight in rice. Although the model system rice-Xanthomonas oryzae pv. oryzae has distinctive features that underpin the need for a case-by-case analysis, strategies to integrate those elements into a unique decision tool could be easily extended to other crops. PMID:25999970

  5. Decision tools for bacterial blight resistance gene deployment in rice-based agricultural ecosystems.

    PubMed

    Dossa, Gerbert S; Sparks, Adam; Cruz, Casiana Vera; Oliva, Ricardo

    2015-01-01

    Attempting to achieve long-lasting and stable resistance using uniformly deployed rice varieties is not a sustainable approach. The real situation appears to be much more complex and dynamic, one in which pathogens quickly adapt to resistant varieties. To prevent disease epidemics, deployment should be customized and this decision will require interdisciplinary actions. This perspective article aims to highlight the current progress on disease resistance deployment to control bacterial blight in rice. Although the model system rice-Xanthomonas oryzae pv. oryzae has distinctive features that underpin the need for a case-by-case analysis, strategies to integrate those elements into a unique decision tool could be easily extended to other crops.

  6. Evolving trends in Streptococcus pneumoniae resistance: implications for therapy of community-acquired bacterial pneumonia.

    PubMed

    Jones, Ronald N; Jacobs, Michael R; Sader, Helio S

    2010-09-01

    Pneumonia is a major infectious disease associated with significant morbidity, mortality and utilisation of healthcare resources. Streptococcus pneumoniae is the predominant pathogen in community-acquired pneumonia (CAP), accounting for 20-60% of bacterial cases. Emergence of multidrug-resistant S. pneumoniae has become a significant problem in the management of CAP. Although pneumococcal conjugate vaccine usage in children has led to significant decreases in morbidity and mortality due to S. pneumoniae in all age groups, disease management has been further complicated by the unexpected increase in resistant serotypes, such as 19A, in some regions. Until rapid and accurate diagnostic tests become available, initial treatment of CAP will remain empirical. Thus, selection of appropriate antimicrobial therapy for CAP must be based on prediction of the most likely pathogens and their local antimicrobial susceptibility patterns. This article reviews information on antimicrobial resistance patterns amongst S. pneumoniae and implications for managing CAP.

  7. Induction of bacterial antibiotic resistance by mutagenic halogenated nitrogenous disinfection byproducts.

    PubMed

    Lv, Lu; Yu, Xin; Xu, Qian; Ye, Chengsong

    2015-10-01

    Halogenated nitrogenous disinfection byproducts (N-DBPs) raise concerns regarding their mutagenicity and carcinogenicity threatening public health. However, environmental consequence of their mutagenicity has received less attention. In this study, the effect of halogenated N-DBPs on bacterial antibiotic resistance (BAR) was investigated. After exposure to bromoacetamide (BAcAm), trichloroacetonitrile (TCAN) or tribromonitromethane (TBNM), the resistance of Pseudomonas aeruginosa PAO1 to both individual and multiple antibiotics (ciprofloxacin, gentamicin, polymyxin B, rifampin, tetracycline, ciprofloxacin + gentamicin and ciprofloxacin + tetracycline) was increased, which was predominantly ascribed to the overexpression of efflux pumps. The mechanism of this effect was demonstrated to be mutagenesis through sequencing and analyzing antibiotic resistance genes. The same induction phenomena also appeared in Escherichia coli, suggesting this effect may be universal to waterborne pathogens. Therefore, more attention should be given to halogenated N-DBPs, as they could increase not only genotoxicological risks but also epidemiological risks of drinking water.

  8. Antibiotics, Antibiotic Resistance Genes, and Bacterial Community Composition in Fresh Water Aquaculture Environment in China.

    PubMed

    Xiong, Wenguang; Sun, Yongxue; Zhang, Tong; Ding, Xueyao; Li, Yafei; Wang, Mianzhi; Zeng, Zhenling

    2015-08-01

    Environmental antibiotic resistance has drawn increasing attention due to its great threat to human health. In this study, we investigated concentrations of antibiotics (tetracyclines, sulfonamides and (fluoro)quinolones) and abundances of antibiotic resistance genes (ARGs), including tetracycline resistance genes, sulfonamide resistance genes, and plasmid-mediated quinolone resistance genes, and analyzed bacterial community composition in aquaculture environment in Guangdong, China. The concentrations of sulfametoxydiazine, sulfamethazine, sulfamethoxazole, oxytetracycline, chlorotetracycline, doxycycline, ciprofloxacin, norfloxacin, and enrofloxacin were as high as 446 μg kg(-1) and 98.6 ng L(-1) in sediment and water samples, respectively. The relative abundances (ARG copies/16S ribosomal RNA (rRNA) gene copies) of ARGs (sul1, sul2, sul3, tetM, tetO, tetW, tetS, tetQ, tetX, tetB/P, qepA, oqxA, oqxB, aac(6')-Ib, and qnrS) were as high as 2.8 × 10(-2). The dominant phyla were Proteobacteria, Bacteroidetes, and Firmicutes in sediment samples and Proteobacteria, Actinobacteria and Bacteroidetes in water samples. The genera associated with pathogens were also observed, such as Acinetobacter, Arcobacter, and Clostridium. This study comprehensively investigated antibiotics, ARGs, and bacterial community composition in aquaculture environment in China. The results indicated that fish ponds are reservoirs of ARGs and the presence of potential resistant and pathogen-associated taxonomic groups in fish ponds might imply the potential risk to human health.

  9. Antibiotic Resistance: New Challenge in the Management of Bacterial Eye Infections.

    PubMed

    Talukder, A K; Sultana, Z; Jahan, I; Khanam, M; Rahman, M; Rahman, M F; Rahman, M B

    2017-01-01

    Ophthalmologists are still facing difficulties in managing bacterial eye infections. The study was designed for the isolation and identification of bacteria from infected eyes and observation of the sensitivity and resistant pattern. This cross sectional study was performed among 160 patients of suspected bacterial eye infection at Dr. K. Zaman BNSB Eye Hospital, Mymensingh and Department of Microbiology and Hygiene, Bangladesh Agricultural University, Mymensingh from March, 2010 to June, 2014. After collection of the samples from suspected infected eyes, it was nourished into nutrient broth in shaking incubator for three hours and then cultured into nutrient agar media followed by Mannitol salt agar, MacConkey's agar and blood agar. Bacteria were categorized by colony characteristics and Gram staining. Antibiogram was performed by disc diffusion method on Mueller Hinton agar media. McFarland Equivalence Turbidity Standard was maintained. The efficacy of the drug was evaluated by measuring the diameter of the zone of inhibition surrounding the disc. Ten percent Staphylococcus species isolates was resistant to Gatifloxacin, Gentamicin, Tobramycin and Cloxacillin, 26.0% to Ciprofloxacin, 40.0% to Azythromycin and Moxifloxacin, 58.0% to Cefixime and 64.0% to Cephalexin. Methicillin resistant Staphylococcus aureus was 62.8%. About 24.0% Streptococcus species isolates was resistant to Gatifloxacin, 33.3% to Azythromycin, Ciprofloxacin, Gentamycin, Moxifloxacin and Tobramycin, 52.4% to Cefixime and 71.4% to Cephalexin. About 9.0% of Pseudomonas species was resistant to Gatifloxacin and Tobramycin, 14.7% to Ciprofloxacin, 26.5% to Cefixime, 29.4% to Gentamicin and Moxifloxacin, 44.1% to Azythromycin and 82.3% to Cephalexin and Cloxacillin. Rational use of antibiotics and proper attentions of concerned authorities are necessary to overcome the emergent ocular situation leaded by antibiotic resistant.

  10. A role for copper in protozoan grazing - two billion years selecting for bacterial copper resistance.

    PubMed

    Hao, Xiuli; Lüthje, Freja; Rønn, Regin; German, Nadezhda A; Li, Xuanji; Huang, Fuyi; Kisaka, Javan; Huffman, David; Alwathnani, Hend A; Zhu, Yong-Guan; Rensing, Christopher

    2016-11-01

    The Great Oxidation Event resulted in integration of soft metals in a wide range of biochemical processes including, in our opinion, killing of bacteria by protozoa. Compared to pressure from anthropologic copper contamination, little is known on impacts of protozoan predation on maintenance of copper resistance determinants in bacteria. To evaluate the role of copper and other soft metals in predatory mechanisms of protozoa, we examined survival of bacteria mutated in different transition metal efflux or uptake systems in the social amoeba Dictyostelium discoideum. Our data demonstrated a strong correlation between the presence of copper/zinc efflux as well as iron/manganese uptake, and bacterial survival in amoebae. The growth of protozoa, in turn, was dependent on bacterial copper sensitivity. The phagocytosis of bacteria induced upregulation of Dictyostelium genes encoding the copper uptake transporter p80 and a triad of Cu(I)-translocating PIB -type ATPases. Accumulated Cu(I) in Dictyostelium was monitored using a copper biosensor bacterial strain. Altogether, our data demonstrate that Cu(I) is ultimately involved in protozoan predation of bacteria, supporting our hypothesis that protozoan grazing selected for the presence of copper resistance determinants for about two billion years.

  11. Bacterial quorum sensing inhibitors: attractive alternatives for control of infectious pathogens showing multiple drug resistance.

    PubMed

    Bhardwaj, Ashima K; Vinothkumar, Kittappa; Rajpara, Neha

    2013-04-01

    Quorum sensing (QS) is a bacterial communication process that depends on the bacterial population density. It involves small diffusible signaling molecules which activate the expression of myriad genes that control diverse array of functions like bioluminescence, virulence, biofilm formation, sporulation, to name a few. Since QS is responsible for virulence in the clinically relevant bacteria, inhibition of QS appears to be a promising strategy to control these pathogenic bacteria. With indiscriminate use of antibiotics, there has been an alarming increase in the number of antibiotic resistant pathogens. Antibiotics are no longer the magic bullets they were once thought to be and therefore there is a need for development of new antibiotics and/or other novel strategies to combat the infections caused by multidrug resistant organisms. Quorum sensing inhibition or quorum quenching has been pursued as one of such novel strategies. While antibiotics kill or slow down the growth of bacteria, quorum sensing inhibitors (QSIs) or quorum quenchers (QQs) attenuate bacterial virulence. A large body of work on QS has been carried out in deadly pathogens like Pseudomonas aeruginosa, Staphylococcus aureus, Vibrio fischeri, V. harveyi, Escherichia coli and V. cholerae etc to unravel the mechanisms of QS as well as identify and study QSIs. This review describes various aspects of QS, QSI, different model systems to study these phenomena and recent patents on various QSIs. It suggests QSIs as attractive alternatives for controlling human, animal and plant pathogens and their utility in agriculture and other industries.

  12. Pipecolic acid enhances resistance to bacterial infection and primes salicylic acid and nicotine accumulation in tobacco.

    PubMed

    Vogel-Adghough, Drissia; Stahl, Elia; Návarová, Hana; Zeier, Juergen

    2013-11-01

    Distinct amino acid metabolic pathways constitute integral parts of the plant immune system. We have recently identified pipecolic acid (Pip), a lysine-derived non-protein amino acid, as a critical regulator of systemic acquired resistance (SAR) and basal immunity to bacterial infection in Arabidopsis thaliana. In Arabidopsis, Pip acts as an endogenous mediator of defense amplification and priming. For instance, Pip conditions plants for effective biosynthesis of the phenolic defense signal salicylic acid (SA), accumulation of the phytoalexin camalexin, and expression of defense-related genes. Here, we show that tobacco plants respond to leaf infection by the compatible bacterial pathogen Pseudomonas syringae pv tabaci (Pstb) with a significant accumulation of several amino acids, including Lys, branched-chain, aromatic, and amide group amino acids. Moreover, Pstb strongly triggers, alongside the biosynthesis of SA and increases in the defensive alkaloid nicotine, the production of the Lys catabolites Pip and α-aminoadipic acid. Exogenous application of Pip to tobacco plants provides significant protection to infection by adapted Pstb or by non-adapted, hypersensitive cell death-inducing P. syringae pv maculicola. Pip thereby primes tobacco for rapid and strong accumulation of SA and nicotine following bacterial infection. Thus, our study indicates that the role of Pip as an amplifier of immune responses is conserved between members of the rosid and asterid groups of eudicot plants and suggests a broad practical applicability for Pip as a natural enhancer of plant disease resistance.

  13. Overexpression of polyphenol oxidase in transgenic tomato plants results in enhanced bacterial disease resistance.

    PubMed

    Li, Li; Steffens, John C

    2002-06-01

    Polyphenol oxidases (PPOs; EC 1.10.3.2 or EC 1.14.18.1) catalyzing the oxygen-dependent oxidation of phenols to quinones are ubiquitous among angiosperms and assumed to be involved in plant defense against pests and pathogens. In order to investigate the role of PPO in plant disease resistance, we made transgenic tomato ( Lycopersicon esculentum Mill. cv. Money Maker) plants that overexpressed a potato ( Solanum tuberosum L.) PPO cDNA under control of the cauliflower mosaic virus 35S promoter. The transgenic plants expressed up to 30-fold increases in PPO transcripts and 5- to 10-fold increases in PPO activity and immunodetectable PPO. As expected, these PPO-overexpressing transgenic plants oxidized the endogenous phenolic substrate pool at a higher rate than control plants. Three independent transgenic lines were selected to assess their interaction with the bacterial pathogen Pseudomonas syringae pv. tomato. The PPO-overexpressing tomato plants exhibited a great increase in resistance to P. syringae. Compared with control plants, these transgenic lines showed less severity of disease symptoms, with over 15-fold fewer lesions, and strong inhibition of bacterial growth, with over 100-fold reduction of bacterial population in the infected leaves. These results demonstrate the importance of PPO-mediated phenolic oxidation in restricting plant disease development.

  14. Bacterial Uropathogens Causing Urinary Tract Infection and Their Resistance Patterns Among Children in Turkey

    PubMed Central

    Yilmaz, Yunus; Tekkanat Tazegun, Zuhal; Aydin, Emsal; Dulger, Mahmut

    2016-01-01

    Background Urinary tract infection (UTI) is a common problem in infants and children, as well as adults. Objectives The aim of this study was to assess the most common bacterial uropathogens, their susceptibility, and resistance to antibiotics in children with UTI. Materials and Methods This study included 7,365 urine samples sent from various departments to the Kars state hospital microbiology laboratory between January 2012 and May 2014. Bacterial isolation from clinical samples was made using standard microbiological methods. Antibiotic susceptibilities were determined by disk diffusion, according to CLSI recommendations. Results Bacterial growth was obtained in 1,373 samples (18.5%). The percentage distributions of the isolates were as follows: Escherichia coli, 940 (68.5%); Proteus spp, 183 (13.3%); Staphylococcus spp, 85 (6.2%); Enterococcus spp, 65 (4.7%); Klebsiella, 62 (4.5%); Pseudomonas aeruginosa, 21 (1.5%); and other Gram-negative bacteria and Gram-positive bacteria, 17 (1.2%). UTIs were more prevalent, after two years of age, among females than males (P < 0.001). Conclusions The identification of the most common microorganisms causing infectious diseases and regional resistance patterns is important in order to determine the antimicrobial policies and infection control guidelines of hospitals. PMID:27621929

  15. Antibacterial activity and mechanism of action of auranofin against multi-drug resistant bacterial pathogens

    PubMed Central

    Thangamani, Shankar; Mohammad, Haroon; Abushahba, Mostafa F. N.; Sobreira, Tiago J. P.; Hedrick, Victoria E.; Paul, Lake N.; Seleem, Mohamed N.

    2016-01-01

    Traditional methods employed to discover new antibiotics are both a time-consuming and financially-taxing venture. This has led researchers to mine existing libraries of clinical molecules in order to repurpose old drugs for new applications (as antimicrobials). Such an effort led to the discovery of auranofin, a drug initially approved as an anti-rheumatic agent, which also possesses potent antibacterial activity in a clinically achievable range. The present study demonstrates auranofin’s antibacterial activity is a complex process that involves inhibition of multiple biosynthetic pathways including cell wall, DNA, and bacterial protein synthesis. We also confirmed that the lack of activity of auranofin observed against Gram-negative bacteria is due to the permeability barrier conferred by the outer membrane. Auranofin’s ability to suppress bacterial protein synthesis leads to significant reduction in the production of key methicillin-resistant Staphylococcus aureus (MRSA) toxins. Additionally, auranofin is capable of eradicating intracellular MRSA present inside infected macrophage cells. Furthermore, auranofin is efficacious in a mouse model of MRSA systemic infection and significantly reduces the bacterial load in murine organs including the spleen and liver. Collectively, this study provides valuable evidence that auranofin has significant promise to be repurposed as a novel antibacterial for treatment of invasive bacterial infections. PMID:26936660

  16. Rainbow trout (Oncorhynchus mykiss) resistance to columnaris disease is heritable and favorably correlated with bacterial cold water disease resistance.

    PubMed

    Evenhuis, J P; Leeds, T D; Marancik, D P; LaPatra, S E; Wiens, G D

    2015-04-01

    Columnaris disease (CD), caused by Flavobacterium columnare, is an emerging disease affecting rainbow trout aquaculture. Objectives of this study were to 1) estimate heritability of CD resistance in a rainbow trout line (ARS-Fp-R) previously selected 4 generations for improved bacterial cold water disease (BCWD) resistance; 2) estimate genetic correlations among CD resistance, BCWD resistance, and growth to market BW; and 3) compare CD resistance among the ARS-Fp-R, ARS-Fp-S (selected 1 generation for increased BCWD susceptibility), and ARS-Fp-C (selection control) lines. Heritability of CD resistance was estimated using data from a waterborne challenge of 44 full-sib ARS-Fp-R families produced using a paternal half-sib mating design, and genetic correlations were estimated using these data and 5 generations of BCWD resistance, 9-mo BW (approximately 0.5 kg), and 12-mo BW (approximately 1.0 kg) data from 405 ARS-Fp-R full-sib families. The CD and BCWD challenges were initiated at approximately 52 and 84 d posthatch, or approximately 650 and 1,050 degree days (°C × d), respectively. Survival of ARS-Fp-R families ranged from 0 to 48% following CD challenge and heritability estimates were similar between CD (0.17 ± 0.09) and BCWD (0.18 ± 0.03) resistance, and the genetic correlation between these 2 traits was favorable (0.35 ± 0.25). Genetic correlations were small and antagonistic (-0.15 ± 0.08 to -0.19 ± 0.24) between the 2 resistance traits and 9- and 12-mo BW. Two challenges were conducted in consecutive years to compare CD resistance among ARS-Fp-R, ARS-Fp-C, and ARS-Fp-S families. In the first challenge, ARS-Fp-R families (83% survival) had greater CD resistance than ARS-Fp-C (73.5%; P = 0.02) and ARS-Fp-S (68%; P < 0.001) families, which did not differ (P = 0.16). In the second challenge, using an approximately 2.5-fold greater challenge dose, ARS-Fp-R families exhibited greater CD resistance (56% survival) than ARS-Fp-S (38% survival; P = 0.02) families

  17. Hidden Selection of Bacterial Resistance to Fluoroquinolones In Vivo: The Case of Legionella pneumophila and Humans

    PubMed Central

    Shadoud, Lubana; Almahmoud, Iyad; Jarraud, Sophie; Etienne, Jérôme; Larrat, Sylvie; Schwebel, Carole; Timsit, Jean-François; Schneider, Dominique; Maurin, Max

    2015-01-01

    Background Infectious diseases are the leading cause of human morbidity and mortality worldwide. One dramatic issue is the emergence of microbial resistance to antibiotics which is a major public health concern. Surprisingly however, such in vivo adaptive ability has not been reported yet for many intracellular human bacterial pathogens such as Legionella pneumophila. Methods We examined 82 unrelated patients with Legionnaire's disease from which 139 respiratory specimens were sampled during hospitalization and antibiotic therapy. We both developed a real time PCR assay and used deep-sequencing approaches to detect antibiotic resistance mutations in L. pneumophila and follow their selection and fate in these samples. Findings We identified the in vivo selection of fluoroquinolone resistance mutations in L. pneumophila in two infected patients treated with these antibiotics. By investigating the mutational dynamics in patients, we showed that antibiotic resistance occurred during hospitalization most likely after fluoroquinolone treatment. Interpretation In vivo selection of antibiotic resistances in L. pneumophila may be associated with treatment failures and poor prognosis. This hidden resistance must be carefully considered in the therapeutic management of legionellosis patients and in the control of the gradual loss of effectiveness of antibiotics. PMID:26501115

  18. Practical survey on antibiotic-resistant bacterial communities in livestock manure and manure-amended soil.

    PubMed

    Yang, Qingxiang; Wang, Ruifei; Ren, Siwei; Szoboszlay, Marton; Moe, Luke A

    2016-01-01

    Through livestock manure fertilization, antibiotics, antibiotic-resistant bacteria and genes are transferred to agricultural soils, resulting in a high prevalence of antibiotic-resistant bacteria in the soil. It is not clear, however, whether a correlation exists between resistant bacterial populations in manure and manure-amended soil. In this work, we demonstrate that the prevalence of cephalexin-, amoxicillin-, kanamycin- and gentamicin-resistant bacteria as well as bacteria simultaneously resistant to all four antibiotics was much higher in manure-amended soils than in manure-free soil. 454-pyrosequencing indicated that the ARB and multiple antibiotic-resistant bacteria (MARB) in swine or chicken manure and manure-amended soil were mainly distributed among Sphingobacterium, Myroides, Enterococcus, Comamonas and unclassified Flavobacteriaceae. The genus Sphingobacterium was highly prevalent among ARB from swine manure and manure-amended soil, and was also the most dominant genus among MARB from chicken manure and manure-amended soil. Other dominant genera among ARB or MARB populations in manure samples, including Myroides, Enterococcus and Comamonas, could not be detected or were detected at very low relative abundance in manure-amended soil. The present study suggests the possibility of transfer of ARBs from livestock manures to soils and persistence of ARB in these environments.

  19. Impact on Bacterial Resistance of Therapeutically Nonequivalent Generics: The Case of Piperacillin-Tazobactam

    PubMed Central

    Rodriguez, Carlos A.; Agudelo, Maria; Aguilar, Yudy A.; Zuluaga, Andres F.

    2016-01-01

    Previous studies have demonstrated that pharmaceutical equivalence and pharmacokinetic equivalence of generic antibiotics are necessary but not sufficient conditions to guarantee therapeutic equivalence (better called pharmacodynamic equivalence). In addition, there is scientific evidence suggesting a direct link between pharmacodynamic nonequivalence of generic vancomycin and promotion of resistance in Staphylococcus aureus. To find out if even subtle deviations from the expected pharmacodynamic behavior with respect to the innovator could favor resistance, we studied a generic product of piperacillin-tazobactam characterized by pharmaceutical and pharmacokinetic equivalence but a faulty fit of Hill’s Emax sigmoid model that could be interpreted as pharmacodynamic nonequivalence. We determined the impact in vivo of this generic product on the resistance of a mixed Escherichia coli population composed of ∼99% susceptible cells (ATCC 35218 strain) and a ∼1% isogenic resistant subpopulation that overproduces TEM-1 β-lactamase. After only 24 hours of treatment in the neutropenic murine thigh infection model, the generic amplified the resistant subpopulation up to 20-times compared with the innovator, following an inverted-U dose-response relationship. These findings highlight the critical role of therapeutic nonequivalence of generic antibiotics as a key factor contributing to the global problem of bacterial resistance. PMID:27191163

  20. Prevalence of bacterial resistance within an eco-agricultural system in Hangzhou, China.

    PubMed

    Xu, Like; Qian, Yanyun; Su, Chao; Cheng, Weixiao; Li, Jianan; Wahlqvist, Mark L; Chen, Hong

    2016-11-01

    The wide use of antibiotics in the animal husbandry and the relevant sustainable industries may promote the emergence of antibiotic-resistant bacteria (ARB), which constitutes a growing threat to human health. The objective of this study was to determine the abundance and diversity of sulfonamide- and tetracycline-resistant bacteria within an eco-agricultural system (EAS) in Hangzhou, China. We investigated samples at every link in the EAS, from livestock manure, to biogas residues and biogas slurry, to vegetable and ryegrass fields, to a fish pond. A combination of culture-based and 16S rRNA gene-based sequencing method was used in this study. Within the studied system, the average rate of bacterial resistance to sulfonamide (46.19 %) was much higher than that of tetracycline (8.51 %) (p < 0.01). There were 224 isolates that were enumerated and sequenced, 108 of which were identified to species level. The genera comprising the sulfamethoxazole-resistant (SMX(r)) bacteria were generally different from those of tetracycline-resistant (TC(r)) bacteria. Staphylococcus and Acinetobacter were the most dominant genera of SMX(r) bacteria (19.30 % of the total resistant bacteria) and TC(r) bacteria (14.04 % of the total resistant bacteria), respectively. Several strains of resistant opportunistic pathogens (e.g., Pantoea agglomerans) were detected in edible vegetable samples, which may exert a potential threat to both pig production and human health. In general, this study indicates that the EAS is an important reservoir of antibiotic-resistant bacteria, some of which may be pathogenic.

  1. PR-13/Thionin but not PR-1 mediates bacterial resistance in Nicotiana attenuata in nature, and neither influences herbivore resistance.

    PubMed

    Rayapuram, Cbgowda; Wu, Jianqiang; Haas, Christiane; Baldwin, Ian T

    2008-07-01

    Increases in pathogenesis-related (PR) transcripts are commonly interpreted as evidence of plants' resistance responses to pathogens; however, few studies have examined whether increases in PR proteins protect plants growing under natural conditions. Pseudomonas syringae pv. tomato DC3,000, which is virulent and causes disease in Arabidopsis, is also pathogenic to the native tobacco Nicotiana attenuata. N. attenuata responds to P. syringae pv. tomato DC3,000's challenges with increases in salicylic acid and transcripts of at least two PR genes, PR-1 and PR13/Thionin. To determine if either of these PR proteins functions in bacterial resistance, we independently silenced both genes by RNAi and found that only PR-13/Thionin mediates resistance to P. syringae pv. tomato DC3,000 in glasshouse experiments. When NaPR-1- and NaThionin-silenced plants were transplanted into the plant's native habitat in the Great Basin Desert of Utah, opportunistic Pseudomonas spp. performed better on NaThionin-silenced plants compared with NaPR-1-silenced and wild-type (WT) plants, and accounted for increased plant mortality. The native herbivore community of N. attenuata attacked both NaPR-1- and PR-13/NaThionin-silenced plants to the same degree as it did in WT plants, indicating that neither PR protein provides resistance to herbivores. Although PR-1 is generally considered a marker gene of disease resistance, we found no evidence that it has an antimicrobial function. In contrast, PR-13/NaThionin is clearly an ecologically relevant defense protein involved in resisting pathogens in N. attenuata.

  2. Proteomics As a Tool for Studying Bacterial Virulence and Antimicrobial Resistance

    PubMed Central

    Pérez-Llarena, Francisco J.; Bou, Germán

    2016-01-01

    Proteomic studies have improved our understanding of the microbial world. The most recent advances in this field have helped us to explore aspects beyond genomics. For example, by studying proteins and their regulation, researchers now understand how some pathogenic bacteria have adapted to the lethal actions of antibiotics. Proteomics has also advanced our knowledge of mechanisms of bacterial virulence and some important aspects of how bacteria interact with human cells and, thus, of the pathogenesis of infectious diseases. This review article addresses these issues in some of the most important human pathogens. It also reports some applications of Matrix-Assisted Laser Desorption/Ionization-Time-Of-Flight (MALDI-TOF) mass spectrometry that may be important for the diagnosis of bacterial resistance in clinical laboratories in the future. The reported advances will enable new diagnostic and therapeutic strategies to be developed in the fight against some of the most lethal bacteria affecting humans. PMID:27065974

  3. Oxidation resistance 1 (OXR1) participates in silkworm defense against bacterial infection through the JNK pathway.

    PubMed

    Su, Li-De; Zhang, Qiao-Ling; Lu, Zhiqiang

    2017-02-01

    Bacterial infection causes enhanced reactive oxygen species (ROS) levels in insects. Oxidation resistance 1 (OXR1) plays an antioxidant role in eukaryotic organisms, including insects. In this report, we demonstrated that Pseudomonas aeruginosa and Staphylococcus aureus infection and hydrogen peroxide (H2 O2 ) injection induced the expression of specific transcriptional isoforms of OXR1 in larval silkworms. We further showed that a Jun kinase (JNK) pathway inhibitor, SP600125, down-regulated expression of OXR1 during infection, leading to elevated H2 O2 levels in the hemolymph, resulting in lower viability of the injected bacteria inside the silkworm larvae. Our study suggests that OXR1 participates in protecting larval silkworms from oxidative stress and bacterial infection through the JNK pathway.

  4. Comparative Resistance of AH26 and a New Sealer Prototype to a Bacterial Challenge

    PubMed Central

    Duggan, Derek; Zhong, Sheng; Rivera, Eric; Arnold, Roland; Simmons, Eric

    2012-01-01

    Objective. This study compared the leakage resistance of a New Sealer Prototype (NSP) with a traditional sealer (AH 26) in Resilon-filled roots subjected to a bacterial challenge. Study Design. 41 roots were instrumented to ISO size 50 apically. Group 1 (n = 20) contained Resilon and AH 26 sealer and roots in group 2 (n = 21) contained Resilon and NSP. Roots were embedded in a dual-chamber model with the upper chamber containing Streptococcus mutans inoculum. Evidence of bacterial penetration was observed for 1 month. Fisher's Test was used to analyze the data. Results. 8 of 20 roots (40%) in the AH 26 group demonstrated leakage whereas 3 of 21 roots (14%) in the NSP group leaked. The difference in leakage rates was not statistically significant (P = 0.053). Conclusion. The traditional sealer (AH 26) demonstrated increased leakage rates compared to the New Sealer Prototype (NSP), but the difference did not reach statistical significance in this study. PMID:22505898

  5. Bacterial diversity and antibiotic resistance in water habitats: searching the links with the human microbiome.

    PubMed

    Vaz-Moreira, Ivone; Nunes, Olga C; Manaia, Célia M

    2014-07-01

    Water is one of the most important bacterial habitats on Earth. As such, water represents also a major way of dissemination of bacteria between different environmental compartments. Human activities led to the creation of the so-called urban water cycle, comprising different sectors (waste, surface, drinking water), among which bacteria can hypothetically be exchanged. Therefore, bacteria can be mobilized between unclean water habitats (e.g. wastewater) and clean or pristine water environments (e.g. disinfected and spring drinking water) and eventually reach humans. In addition, bacteria can also transfer mobile genetic elements between different water types, other environments (e.g. soil) and humans. These processes may involve antibiotic resistant bacteria and antibiotic resistance genes. In this review, the hypothesis that some bacteria may share different water compartments and be also hosted by humans is discussed based on the comparison of the bacterial diversity in different types of water and with the human-associated microbiome. The role of such bacteria as potential disseminators of antibiotic resistance and the inference that currently only a small fraction of the clinically relevant antibiotic resistome may be known is discussed.

  6. Parallel Loss-of-Function at the RPM1 Bacterial Resistance Locus in Arabidopsis thaliana

    PubMed Central

    Rose, Laura; Atwell, Susanna; Grant, Murray; Holub, Eric B.

    2012-01-01

    Dimorphism at the Resistance to Pseudomonas syringae pv. maculicola 1 (RPM1) locus is well documented in natural populations of Arabidopsis thaliana and has been portrayed as a long-term balanced polymorphism. The haplotype from resistant plants contains the RPM1 gene, which enables these plants to recognize at least two structurally unrelated bacterial effector proteins (AvrB and AvrRpm1) from bacterial crop pathogens. A complete deletion of the RPM1 coding sequence has been interpreted as a single event resulting in susceptibility in these individuals. Consequently, the ability to revert to resistance or for alternative R-gene specificities to evolve at this locus has also been lost in these individuals. Our survey of variation at the RPM1 locus in a large species-wide sample of A. thaliana has revealed four new loss-of-function alleles that contain most of the intervening sequence of the RPM1 open reading frame. Multiple loss-of-function alleles may have originated due to the reported intrinsic cost to plants expressing the RPM1 protein. The frequency and geographic distribution of rpm1 alleles observed in our survey indicate the parallel origin and maintenance of these loss-of-function mutations and reveal a more complex history of natural selection at this locus than previously thought. PMID:23272006

  7. PHACOS, a functionalized bacterial polyester with bactericidal activity against methicillin-resistant Staphylococcus aureus

    PubMed Central

    Dinjaski, Nina; Fernández-Gutiérrez, Mar; Selvam, Shivaram; Parra-Ruiz, Francisco J.; Lehman, Susan M.; Román, Julio San; García, Ernesto; García, José L.; García, Andrés J.; Prieto, María Auxiliadora

    2013-01-01

    Biomaterial-associated infections represent a significant clinical problem, and treatment of these microbial infections is becoming troublesome due to the increasing number of antibiotic-resistant strains. Here, we report a naturally functionalized bacterial polyhydroxyalkanoate (PHACOS) with antibacterial properties. We demonstrate that PHACOS selectively and efficiently inhibits the growth of methicillin-resistant Staphylococcus aureus (MRSA) both in vitro and in vivo. This ability has been ascribed to the functionalized side chains containing thioester groups. Significantly less (3.2-fold) biofilm formation of S. aureus was detected on PHACOS compared to biofilms formed on control poly(3-hydroxyoctanoate-co-hydroxyhexanoate) and poly(ethylene terephthalate), but no differences were observed in bacterial adhesion among these polymers. PHACOS elicited minimal cytotoxic and inflammatory effects on murine macrophages and supported normal fibroblast adhesion. In vivo fluorescence imaging demonstrated minimal inflammation and excellent antibacterial activity for PHACOS compared to controls in an in vivo model of implant-associated infection. Additionally, reductions in neutrophils and macrophages in the vicinity of sterile PHACOS compared to sterile PHO implant were observed by immunohistochemistry. Moreover, a similar percentage of inflammatory cells was found in the tissue surrounding sterile PHACOS and S. aureus pre-colonized PHACOS implants, and these levels were significantly lower than S. aureus pre-colonized control polymers. These findings support a contact active surface mode of antibacterial action for PHACOS and establish this functionalized polyhydroxyalkanoate as an infection-resistant biomaterial. PMID:24094939

  8. Gene Expression Variability Underlies Adaptive Resistance in Phenotypically Heterogeneous Bacterial Populations.

    PubMed

    Erickson, Keesha E; Otoupal, Peter B; Chatterjee, Anushree

    2015-11-13

    The root cause of the antibiotic resistance crisis is the ability of bacteria to evolve resistance to a multitude of antibiotics and other environmental toxins. The regulation of adaptation is difficult to pinpoint due to extensive phenotypic heterogeneity arising during evolution. Here, we investigate the mechanisms underlying general bacterial adaptation by evolving wild-type Escherichia coli populations to dissimilar chemical toxins. We demonstrate the presence of extensive inter- and intrapopulation phenotypic heterogeneity across adapted populations in multiple traits, including minimum inhibitory concentration, growth rate, and lag time. To search for a common response across the heterogeneous adapted populations, we measured gene expression in three stress-response networks: the mar regulon, the general stress response, and the SOS response. While few genes were differentially expressed, clustering revealed that interpopulation gene expression variability in adapted populations was distinct from that of unadapted populations. Notably, we observed both increases and decreases in gene expression variability upon adaptation. Sequencing select genes revealed that the observed gene expression trends are not necessarily attributable to genetic changes. To further explore the connection between gene expression variability and adaptation, we propagated single-gene knockout and CRISPR (clustered regularly interspaced short palindromic repeats) interference strains and quantified impact on adaptation to antibiotics. We identified significant correlations that suggest genes with low expression variability have greater impact on adaptation. This study provides evidence that gene expression variability can be used as an indicator of bacterial adaptive resistance, even in the face of the pervasive phenotypic heterogeneity underlying adaptation.

  9. Predicting bacterial resistance using the time inside the mutant selection window: possibilities and limitations.

    PubMed

    Firsov, Alexander A; Portnoy, Yury A; Strukova, Elena N; Shlykova, Darya S; Zinner, Stephen H

    2014-10-01

    The time inside the mutant selection window (TMSW) has been shown to be less predictive of selection of fluoroquinolone-resistant bacteria than the ratio of the area under the concentration-time curve to minimum inhibitory concentration (AUC/MIC). To explore the different predictive powers of TMSW and AUC/MIC, enrichment of ciprofloxacin-resistant mutants of four Escherichia coli strains was studied in an in vitro dynamic model at widely ranging TMSW values. Each organism was exposed to twice-daily ciprofloxacin for 3 days. Peak antibiotic concentrations were simulated to be close to the MIC, between the MIC and the mutant prevention concentration (MPC), and above the MPC, with TMSW varying from 0% to 100% of the dosing interval. Amplification of resistant mutants was monitored by plating on medium with 8× MIC of the antibiotic. For each organism, TMSW plots of the area under the bacterial mutant concentration-time curve (AUBCM) exhibited a hysteresis loop: at a given TMSW that corresponds to the points on the ascending portion of the bell-shaped AUBCM-AUC/MIC curve [when the time above the MPC (T>MPC) was zero], the AUBCM was greater than at the same TMSW related to the descending portion (T>MPC>0). A sigmoid function fits these separate data sets well for combined data with the four organisms (r(2)=0.81 and 0.92, respectively), in contrast to fitting the whole data pool while ignoring the AUC/MIC-resistance relationship (r(2)=0.61). These data allow the appropriate use of TMSW as a predictor of bacterial resistance.

  10. High-resolution genetic mapping of rice bacterial blight resistance gene Xa23.

    PubMed

    Wang, Chunlian; Fan, Yinglun; Zheng, Chongke; Qin, Tengfei; Zhang, Xiaoping; Zhao, Kaijun

    2014-10-01

    Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is the most devastating bacterial disease of rice (Oryza sativa L.), a staple food crop that feeds half of the world's population. In management of this disease, the most economical and effective approach is cultivating resistant varieties. Due to rapid change of pathogenicity in the pathogen, it is necessary to identify and characterize more host resistance genes for breeding new resistant varieties. We have previously identified the BB resistance (R) gene Xa23 that confers the broadest resistance to Xoo strains isolated from different rice-growing regions and preliminarily mapped the gene within a 1.7 cm region on the long arm of rice chromosome 11. Here, we report fine genetic mapping and in silico analysis of putative candidate genes of Xa23. Based on F2 mapping populations derived from crosses between Xa23-containing rice line CBB23 and susceptible varieties JG30 or IR24, six new STS markers Lj36, Lj46, Lj138, Lj74, A83B4, and Lj13 were developed. Linkage analysis revealed that the new markers were co-segregated with or closely linked to the Xa23 locus. Consequently, the Xa23 gene was mapped within a 0.4 cm region between markers Lj138 and A83B4, in which the co-segregating marker Lj74 was identified. The corresponding physical distance between Lj138 and A83B4 on Nipponbare genome is 49.8 kb. Six Xa23 candidate genes have been annotated, including four candidate genes encoding hypothetical proteins and the other two encoding a putative ADP-ribosylation factor protein and a putative PPR protein. These results will facilitate marker-assisted selection of Xa23 in rice breeding and molecular cloning of this valuable R gene.

  11. New insights in the bacterial spore resistance to extreme terrestrial and extraterrestrial factors

    NASA Astrophysics Data System (ADS)

    Moeller, Ralf; Horneck, Gerda; Reitz, Guenther

    Based on their unique resistance to various space parameters, Bacillus endospores are one of the model systems used for astrobiological studies. The extremely high resistance of bacterial endospores to environmental stress factors has intrigued researchers since long time and many characteristic spore features, especially those involved in the protection of spore DNA, have already been uncovered. The disclosure of the complete genomic sequence of Bacillus subtilis 168, one of the often used astrobiological model system, and the rapid development of tran-scriptional microarray techniques have opened new opportunities of gaining further insights in the enigma of spore resistance. Spores of B. subtilis were exposed to various extreme ter-restrial and extraterrestrial stressors to reach a better understanding of the DNA protection and repair strategies, which them to cope with the induced DNA damage. Following physical stress factors of environmental importance -either on Earth or in space -were selected for this thesis: (i) mono-and polychromatic UV radiation, (ii) ionizing radiation, (iii) exposure to ultrahigh vacuum; and (iv) high shock pressures simulating meteorite impacts. To reach a most comprehensive understanding of spore resistance to those harsh terrestrial or simulated extraterrestrial conditions, a standardized experimental protocol of the preparation and ana-lyzing methods was established including the determination of the following spore responses: (i) survival, (ii) induced mutations, (iii) DNA damage, (iv) role of different repair pathways by use of a set of repair deficient mutants, and (v) transcriptional responses during spore germi-nation by use of genome-wide transcriptome analyses and confirmation by RT-PCR. From this comprehensive set of data on spore resistance to a variety of environmental stress parameters a model of a "built-in" transcriptional program of bacterial spores in response to DNA damaging treatments to ensure DNA restoration

  12. In Vitro Evaluation of the Risk of Inducing Bacterial Resistance to Disinfection Treatment with Photolysis of Hydrogen Peroxide

    PubMed Central

    Ikai, Hiroyo; Odashima, Yu; Kanno, Taro; Nakamura, Keisuke; Shirato, Midori; Sasaki, Keiichi; Niwano, Yoshimi

    2013-01-01

    The purpose of the present study was to evaluate the risk of inducing bacterial resistance to disinfection treatment with photolysis of H2O2 and comparing this with existing antibacterial agents. We tested seven antibacterial agents, including amoxicillin, cefepime hydrochloride, erythromycin, ofloxacin, clindamycin hydrochloride, ciprofloxacin hydrochloride, and minocycline hydrochloride, as positive controls for validation of the assay protocol. For all of the agents tested, at least one of the four bacterial species (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Streptococcus salivarius) was resistant to these agents by repeated exposure to subinhibitory concentrations of the agents up to 10 times. In contrast, antibacterial activity against any of the bacterial species tested (S. aureus, E. faecalis, E. coli, S. salivarius, Pseudomonas aeruginosa, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans) was not affected by repeated exposure to the disinfection treatment up to 40 times. This finding suggested that the risk of inducing bacterial resistance by disinfection treatment was low. The active ingredient of this disinfection treatment is hydroxyl radicals generated by photolysis of H2O2. Therefore, hydroxyl radicals interact with several cell structures and different metabolic pathways in microbial cells, probably resulting in a lack of development of bacterial resistance. In conclusion, disinfection treatment with photolysis of H2O2 appears to be a potential alternative for existing antimicrobial agents in terms of a low risk of inducing bacterial resistance. PMID:24282582

  13. In vitro evaluation of the risk of inducing bacterial resistance to disinfection treatment with photolysis of hydrogen peroxide.

    PubMed

    Ikai, Hiroyo; Odashima, Yu; Kanno, Taro; Nakamura, Keisuke; Shirato, Midori; Sasaki, Keiichi; Niwano, Yoshimi

    2013-01-01

    The purpose of the present study was to evaluate the risk of inducing bacterial resistance to disinfection treatment with photolysis of H2O2 and comparing this with existing antibacterial agents. We tested seven antibacterial agents, including amoxicillin, cefepime hydrochloride, erythromycin, ofloxacin, clindamycin hydrochloride, ciprofloxacin hydrochloride, and minocycline hydrochloride, as positive controls for validation of the assay protocol. For all of the agents tested, at least one of the four bacterial species (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Streptococcus salivarius) was resistant to these agents by repeated exposure to subinhibitory concentrations of the agents up to 10 times. In contrast, antibacterial activity against any of the bacterial species tested (S. aureus, E. faecalis, E. coli, S. salivarius, Pseudomonas aeruginosa, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans) was not affected by repeated exposure to the disinfection treatment up to 40 times. This finding suggested that the risk of inducing bacterial resistance by disinfection treatment was low. The active ingredient of this disinfection treatment is hydroxyl radicals generated by photolysis of H2O2. Therefore, hydroxyl radicals interact with several cell structures and different metabolic pathways in microbial cells, probably resulting in a lack of development of bacterial resistance. In conclusion, disinfection treatment with photolysis of H2O2 appears to be a potential alternative for existing antimicrobial agents in terms of a low risk of inducing bacterial resistance.

  14. Molecular Mapping of High Resistance to Bacterial Leaf Spot in Lettuce PI 358001-1.

    PubMed

    Wang, Yunwen; Lu, Huangjun; Hu, Jinguo

    2016-11-01

    Lettuce (Lactuca sativa L.) is a diploid (2n = 18) with a genome size of 2,600 Mbp, and belongs to the family Compositae. Bacterial leaf spot (BLS), caused by Xanthomonas campestris pv. vitians, is a major disease of lettuce worldwide. Leaf lettuce PI 358001-1 has been characterized as an accession highly resistant to BLS and has white seed. In order to understand inheritance of the high resistance in this germplasm line, an F3 population consisting of 163 families was developed from the cross PI 358001-1 × 'Tall Guzmaine' (a susceptible Romaine lettuce variety with black seed). The segregation ratio of reaction to disease by seedling inoculation with X. campestris pv. vitians L7 strain in the F3 families was shown to be 32:82:48 homozygous resistant/heterozygous/homozygous susceptible, fitting to 1:2:1 (n = 162, χ(2) = 3.19, P = 0.20). The segregation ratio of seed color by checking F2 plants was 122:41 black/white, fitting to 3:1 (n = 163, χ(2) = 0.002, P = 0.96). The results indicated that both BLS resistance and seed color were inherited as a dominant gene mode. A genetic linkage map based on 124 randomly selected F2 plants was developed to enable molecular mapping of the BLS resistance and the seed color trait. In total, 199 markers, comprising 176 amplified fragment length polymorphisms, 16 simple-sequence repeats, 5 resistant gene candidate markers, and 2 cleaved amplified polymorphic sequences (CAPS) markers were assigned to six linkage groups. The dominant resistance gene to BLS (Xcvr) was mapped on linkage group 2 and the gene locus y for seed color was identified on linkage group 5. Due to the nature of a single gene inheritance, the high-resistance gene should be readily transferred to adapted lettuce cultivars to battle against the devastating disease of lettuce.

  15. Rapid Detection of Bacterial Antibiotic Resistance: Preliminary Evaluation of PCR Assays Targeting Tetracycline Resistance Genes

    DTIC Science & Technology

    2007-08-01

    Molecular analysis of rifampin resistance in Bacillus anthracis and Bacillus cereus . Antimicrobial Agents and Chemotherapy 46: 511-513 15 DSTO-TR...fever. Infections like inhalation anthrax and pneumonic plague, caused by Bacillus anthracis and Yersinia pestis, have to be treated with an effective...Table 1. Antibiotics commonly used against diseases caused by potential BW agents Organism Disease Antibiotics Bacillus anthracis Anthrax Ciprofloxacin

  16. Evidence of major genes affecting bacterial cold water disease resistance in rainbow trout using Bayesian methods of complex segregation analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial cold water disease (BCWD) causes significant economic loss in salmonid aquaculture. We previously detected genetic variation for BCWD resistance in our rainbow trout population, and a family-based selection program to improve resistance was initiated at the NCCCWA in 2005. The main objec...

  17. Evidence of major genes affecting resistance to bacterial cold water disease in rainbow trout using Bayesian methods of segregation analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial cold water disease (BCWD) causes significant economic loss in salmonid aquaculture. We previously detected genetic variation for BCWD resistance in our rainbow trout population, and a family-based selection program to improve resistance was initiated at the National Center for Cool and Col...

  18. Baby leaf lettuce germplasm enhancement: developing diverse populations with resistance to bacterial leaf spot caused by Xanthomonas campestris pv. vitians

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Baby leaf lettuce cultivars with resistance to bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vitians (Xcv) are needed to reduce crop losses. The objectives of this research were to assess the genetic diversity for BLS resistance in baby leaf lettuce cultivars and to select early gen...

  19. Covalently linked kanamycin - Ciprofloxacin hybrid antibiotics as a tool to fight bacterial resistance.

    PubMed

    Shavit, Michal; Pokrovskaya, Varvara; Belakhov, Valery; Baasov, Timor

    2017-03-16

    To address the growing problem of antibiotic resistance, a set of 12 hybrid compounds that covalently link fluoroquinolone (ciprofloxacin) and aminoglycoside (kanamycin A) antibiotics were synthesized, and their activity was determined against both Gram-negative and Gram-positive bacteria, including resistant strains. The hybrids were antagonistic relative to the ciprofloxacin, but were substantially more potent than the parent kanamycin against Gram-negative bacteria, and overcame most dominant resistance mechanisms to aminoglycosides. Selected hybrids were 42-640 fold poorer inhibitors of bacterial protein synthesis than the parent kanamycin, while they displayed similar inhibitory activity to that of ciprofloxacin against DNA gyrase and topoisomerase IV enzymes. The hybrids showed significant delay of resistance development in both E. coli and B. subtilis in comparison to that of component drugs alone or their 1:1 mixture. More generally, the data suggest that an antagonistic combination of aminoglycoside-fluoroquinolone hybrids can lead to new compounds that slowdown/prevent the emergence of resistance.

  20. Antimicrobial Resistance and Plasmid Profile of Bacterial Strains Isolated from the Urbanized Eltsovka-1 River (Russia).

    PubMed

    Lobova, Tatiana I; Yemelyanova, Elena; Andreeva, Irina S; Puchkova, Larisa I; Repin, Vladimir Ye

    2015-08-01

    Antimicrobial resistance and plasmid profile of Gram-positive and Gram-negative bacterial strains isolated from the urbanized Eltsovka-1 River (Russia) were investigated. Sequencing of the 16S rRNA of of G+ strains showed 99-100% identity to that of Bacillus aerophilus, Bacillus altitudinis, Bacillus amyloliquefaciens, Bacillus anthrancis, Bacillus barbaricus, Bacillus cereus, Bacillus flexus, Bacillus indriensis, Bacillus stratosphericus, Bacillus subtilis subsp. subtilis, Bacillus thuringiensis, Streptomyces albidoflavus, Streptomyces albus, Streptomyces exfoliatus, Streptomyces odorifer, and Streptomyces sampsonii. Sequencing of the 16S rRNA of G-strains was similar in 99-100% to that of Aeromonas bestiarum, Aeromonas encheleia, Aeromonas hydrophila, A. hydrophila subsp. anaerogenes, A. hydrophila subsp. dhakensis, Aeromonas media, Aeromonas molluscorum, Aeromonas popoffii, Aeromonas salmonicida subsp. masoucida, A. salmonicida subsp. pectinolytica, A. salmonicida subsp. salmonicida, Aeromonas punctata, Aeromonas sobria, and Shewanella putrefaciens. The highest percentage (88.4%) of strains was resistant to polymyxin B followed by 69% to lincomycin, 61.5% to benzilpenicillin, 57.7% to ampicillin, and 50% to carbenicillin. A low level of resistance (4%) was found to kanamycin (8%), to streptomycin (11.5%), to neomycin and tetracycline, and (15%) to erythromycin. No resistance was found to gentamycin, monomycin, and chloroamphenicol. The majority (80.7%) of strains was multidrug-resistant. Ninety-two percent of all strains carried plasmid DNA of various sizes.

  1. Expression of the Bs2 pepper gene confers resistance to bacterial spot disease in tomato

    PubMed Central

    Tai, Thomas H.; Dahlbeck, Douglas; Clark, Eszter T.; Gajiwala, Paresh; Pasion, Romela; Whalen, Maureen C.; Stall, Robert E.; Staskawicz, Brian J.

    1999-01-01

    The Bs2 resistance gene of pepper specifically recognizes and confers resistance to strains of Xanthomonas campestris pv. vesicatoria that contain the corresponding bacterial avirulence gene, avrBs2. The involvement of avrBs2 in pathogen fitness and its prevalence in many X. campestris pathovars suggests that the Bs2 gene may be durable in the field and provide resistance when introduced into other plant species. Employing a positional cloning strategy, the Bs2 locus was isolated and the gene was identified by coexpression with avrBs2 in an Agrobacterium-mediated transient assay. A single candidate gene, predicted to encode motifs characteristic of the nucleotide binding site–leucine-rich repeat class of resistance genes, was identified. This gene specifically controlled the hypersensitive response when transiently expressed in susceptible pepper and tomato lines and in a nonhost species, Nicotiana benthamiana, and was designated as Bs2. Functional expression of Bs2 in stable transgenic tomatoes supports its use as a source of resistance in other Solanaceous plant species. PMID:10570214

  2. Classification tree method for bacterial source tracking with antibiotic resistance analysis data.

    PubMed

    Price, Bertram; Venso, Elichia A; Frana, Mark F; Greenberg, Joshua; Ware, Adam; Currey, Lee

    2006-05-01

    Various statistical classification methods, including discriminant analysis, logistic regression, and cluster analysis, have been used with antibiotic resistance analysis (ARA) data to construct models for bacterial source tracking (BST). We applied the statistical method known as classification trees to build a model for BST for the Anacostia Watershed in Maryland. Classification trees have more flexibility than other statistical classification approaches based on standard statistical methods to accommodate complex interactions among ARA variables. This article describes the use of classification trees for BST and includes discussion of its principal parameters and features. Anacostia Watershed ARA data are used to illustrate the application of classification trees, and we report the BST results for the watershed.

  3. Comparison of Metals and Tetracycline as Selective Agents for Development of Tetracycline Resistant Bacterial Communities in Agricultural Soil.

    PubMed

    Song, Jianxiao; Rensing, Christopher; Holm, Peter E; Virta, Marko; Brandt, Kristian K

    2017-03-07

    Environmental selection of antibiotic resistance may be caused by either antibiotic residues or coselecting agents. Using a strictly controlled experimental design, we compared the ability of metals (Cu or Zn) and tetracycline to (co)select for tetracycline resistance in bacterial communities. Soil microcosms were established by amending agricultural soil with known levels of Cu, Zn, or tetracycline known to represent commonly used metals and antibiotics for pig farming. Soil bacterial growth dynamics and bacterial community-level tetracycline resistance were determined using the [(3)H]leucine incorporation technique, whereas soil Cu, Zn, and tetracycline exposure were quantified by a panel of whole-cell bacterial bioreporters. Tetracycline resistance increased significantly in soils containing environmentally relevant levels of Cu (≥365 mg kg(-1)) and Zn (≥264 mg kg(-1)) but not in soil spiked with unrealistically high levels of tetracycline (up to 100 mg kg(-1)). These observations were consistent with bioreporter data showing that metals remained bioavailable, whereas tetracycline was only transiently bioavailable. Community-level tetracycline resistance was correlated to the initial toxicant-induced inhibition of bacterial growth. In conclusion, our study demonstrates that toxic metals in some cases may exert a stronger selection pressure for environmental selection of resistance to an antibiotic than the specific antibiotic itself.

  4. Prevalence of antibacterial resistant bacterial contaminants from mobile phones of hospital inpatients.

    PubMed

    Vinod Kumar, B; Hobani, Yahya Hasan; Abdulhaq, Ahmed; Jerah, Ahmed Ali; Hakami, Othman M; Eltigani, Magdeldin; Bidwai, Anil K

    2014-01-01

    Mobile phones contaminated with bacteria may act as fomites. Antibiotic resistant bacterial contamination of mobile phones of inpatients was studied. One hundred and six samples were collected from mobile phones of patients admitted in various hospitals in Jazan province of Saudi Arabia. Eighty-nine (83.9%) out of 106 mobile phones were found to be contaminated with bacteria. Fifty-two (49.0%) coagulase-negative Staphylococcus, 12 (11.3%) Staphylococcus aureus, 7 (6.6%) Enterobacter cloacae, 3 (2.83%) Pseudomonas stutzeri, 3 (2.83%) Sphingomonas paucimobilis, 2 (1.8%) Enterococcus faecalis and 10 (9.4%) aerobic spore bearers were isolated. All the isolated bacteria were found to be resistant to various antibiotics. Hence, regular disinfection of mobile phones of hospital inpatients is advised.

  5. Origin and Proliferation of Multiple-Drug Resistance in Bacterial Pathogens

    PubMed Central

    Chang, Hsiao-Han; Cohen, Ted; Grad, Yonatan H.; Hanage, William P.; O'Brien, Thomas F.

    2015-01-01

    SUMMARY Many studies report the high prevalence of multiply drug-resistant (MDR) strains. Because MDR infections are often significantly harder and more expensive to treat, they represent a growing public health threat. However, for different pathogens, different underlying mechanisms are traditionally used to explain these observations, and it is unclear whether each bacterial taxon has its own mechanism(s) for multidrug resistance or whether there are common mechanisms between distantly related pathogens. In this review, we provide a systematic overview of the causes of the excess of MDR infections and define testable predictions made by each hypothetical mechanism, including experimental, epidemiological, population genomic, and other tests of these hypotheses. Better understanding the cause(s) of the excess of MDR is the first step to rational design of more effective interventions to prevent the origin and/or proliferation of MDR. PMID:25652543

  6. [Differential expression of genes related to bacterial wilt resistance in peanut (Arachis hypogaea L.)].

    PubMed

    Peng, Wen-Fang; Lv, Jian-Wei; Ren, Xiao-Ping; Huang, Li; Zhao, Xin-Yan; Wen, Qi-Gen; Jiang, Hui-Fang

    2011-04-01

    Peanut bacterial wilt (BW) caused by Ralstonia solanacearum is one of the most devastating diseases for peanut production in the world. It is believed that breeding and subsequent planting BW-resistant cultivars of peanut (Arachis hypogaea L.) should represent the most effective and economic means of controlling the disease. To illustrate the molecular mechanism of peanut resistant to BW, a BW-resistant cultivar, 'Yuanza 9102', and a BW-sensitive one, 'Zhonghua 12', were infected with Ralstonia solanacearum and differential expression of the genes related to BW-resistance was analyzed using complementary DNA amplified length polymorphism (cDNA-AFLP) technique. The infected 3-leaflet seedlings were followed for 48 h and root samples were taken at 0, 2, 10, 24 and 48 h after inoculation, respectively. A total of 12596 transcript-derived fragments (TDFs) were amplified with 256 primer combinations, including 709 differential expressed TDFs, which were generated from 119 primer combinations. Ninety-eight TDFs were randomly chosen for DNA sequence analysis. BLASTx analysis of the obtained sequences revealed that 40 TDFs encoded gene products associated with energy, transcription, signal transduction, defense, metabolism, cell growth, cell structure or/and protein synthesis. Analysis of the expression of four genes by qRT-PCR verified the results from cDNA-AFLP. Strikingly, one of the identified TDFs, 32-54-1, occurred for 47 times in a known BW-resistant SSH library. These results suggest that resistance to BW in peanut involves multifaceted biochemical and physiological reactions, including regulation of the genes involved in different pathways, such as defense, singal transduction, metabolism, transcription and abiotic stresses. The TDF 32-54-1 was predicted to be closely related to BW resistance in peanut.

  7. Vancomycin-Resistant Enterococci and Bacterial Community Structure following a Sewage Spill into an Aquatic Environment

    PubMed Central

    Young, Suzanne; Nayak, Bina; Sun, Shan; Badgley, Brian D.; Rohr, Jason R.

    2016-01-01

    ABSTRACT Sewage spills can release antibiotic-resistant bacteria into surface waters, contributing to environmental reservoirs and potentially impacting human health. Vancomycin-resistant enterococci (VRE) are nosocomial pathogens that have been detected in environmental habitats, including soil, water, and beach sands, as well as wildlife feces. However, VRE harboring vanA genes that confer high-level resistance have infrequently been found outside clinical settings in the United States. This study found culturable Enterococcus faecium harboring the vanA gene in water and sediment for up to 3 days after a sewage spill, and the quantitative PCR (qPCR) signal for vanA persisted for an additional week. Culturable levels of enterococci in water exceeded recreational water guidelines for 2 weeks following the spill, declining about five orders of magnitude in sediments and two orders of magnitude in the water column over 6 weeks. Analysis of bacterial taxa via 16S rRNA gene sequencing showed changes in community structure through time following the sewage spill in sediment and water. The spread of opportunistic pathogens harboring high-level vancomycin resistance genes beyond hospitals and into the broader community and associated habitats is a potential threat to public health, requiring further studies that examine the persistence, occurrence, and survival of VRE in different environmental matrices. IMPORTANCE Vancomycin-resistant enterococci (VRE) are harmful bacteria that are resistant to the powerful antibiotic vancomycin, which is used as a last resort against many infections. This study followed the release of VRE in a major sewage spill and their persistence over time. Such events can act as a means of spreading vancomycin-resistant bacteria in the environment, which can eventually impact human health. PMID:27422829

  8. Exploiting bacterial drug resistance: a single construct for the diagnosis and treatment of drug resistant infections

    NASA Astrophysics Data System (ADS)

    Sallum, Ulysses W.; Zheng, Xiang; Verma, Sarika; Hasan, Tayyaba

    2009-06-01

    β-lactamase enzyme-activated photosensitizer (β-LEAP). We aim to exploit drug resistance mechanisms to selectively release photosensitizers (PSs) for a specific photodynamic antimicrobial effect and reduced host tissue damage. Consequently, the fluorescence emission intensity of the PSs increases and allows for the detection of enzyme activity. In this work we sought to evaluate β-LEAP for use as a sensitive molecular probe. We have reported the enzyme specific antibacterial action of β-LEAP. Here we report the use of β-LEAP for the rapid functional definition of a β-lactamase.

  9. Interactions of Antibiotics and Methanolic Crude Extracts of Afzelia Africana (Smith.) Against Drug Resistance Bacterial Isolates

    PubMed Central

    Aiyegoro, Olayinka; Adewusi, Adekanmi; Oyedemi, Sunday; Akinpelu, David; Okoh, Anthony

    2011-01-01

    Infection due to multidrug resistance pathogens is difficult to manage due to bacterial virulence factors and because of a relatively limited choice of antimicrobial agents. Thus, it is imperative to discover fresh antimicrobials or new practices that are effective for the treatment of infectious diseases caused by drug-resistant microorganisms. The objective of this experiment is to investigate for synergistic outcomes when crude methanolic extract of the stem bark of Afzelia africana and antibiotics were combined against a panel of antibiotic resistant bacterial strains that have been implicated in infections. Standard microbiological protocols were used to determine the minimum inhibitory concentrations (MICs) of the extract and antibiotics, as well as to investigate the effect of combinations of the methanolic extract of A. africana stem bark and selected antibiotics using the time-kill assay method. The extract of Afzelia africana exhibited antibacterial activities against both Gram-negative and Gram-positive bacteria made up of environmental and standard strains at a screening concentration of 5 mg/mL. The MICs of the crude extracts and the antibiotics varied between 1 μg/mL and 5.0 mg/mL. Overall, synergistic response constituted about 63.79% of all manner of combinations of extract and antibiotics against all test organisms; antagonism was not detected among the 176 tests carried out. The extract from A. africana stem bark showed potentials of synergy in combination with antibiotics against strains of pathogenic bacteria. The detection of synergy between the extract and antibiotics demonstrates the potential of this plant as a source of antibiotic resistance modulating compounds. PMID:21845091

  10. Genome-wide association analysis identifies resistance loci for bacterial blight in a diverse collection of indica rice germplasm.

    PubMed

    Zhang, Fan; Wu, Zhi-Chao; Wang, Ming-Ming; Zhang, Fan; Dingkuhn, Michael; Xu, Jian-Long; Zhou, Yong-Li; Li, Zhi-Kang

    2017-01-01

    Bacterial blight, which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating rice diseases worldwide. The development and use of disease-resistant cultivars have been the most effective strategy to control bacterial blight. Identifying the genes mediating bacterial blight resistance is a prerequisite for breeding cultivars with broad-spectrum and durable resistance. We herein describe a genome-wide association study involving 172 diverse Oryza sativa ssp. indica accessions to identify loci influencing the resistance to representative strains of six Xoo races. Twelve resistance loci containing 121 significantly associated signals were identified using 317,894 single nucleotide polymorphisms, which explained 13.3-59.9% of the variability in lesion length caused by Xoo races P1, P6, and P9a. Two hotspot regions (L11 and L12) were located within or nearby two cloned R genes (xa25 and Xa26) and one fine-mapped R gene (Xa4). Our results confirmed the relatively high resolution of genome-wide association studies. Moreover, we detected novel significant associations on chromosomes 2, 3, and 6-10. Haplotype analyses of xa25, the Xa26 paralog (MRKc; LOC_Os11g47290), and a Xa4 candidate gene (LOC_11g46870) revealed differences in bacterial blight resistance among indica subgroups. These differences were responsible for the observed variations in lesion lengths resulting from infections by Xoo races P1 and P9a. Our findings may be relevant for future studies involving bacterial blight resistance gene cloning, and provide insights into the genetic basis for bacterial blight resistance in indica rice, which may be useful for knowledge-based crop improvement.

  11. Genome-wide association analysis identifies resistance loci for bacterial blight in a diverse collection of indica rice germplasm

    PubMed Central

    Wang, Ming-Ming; Zhang, Fan; Dingkuhn, Michael; Xu, Jian-Long; Zhou, Yong-Li; Li, Zhi-Kang

    2017-01-01

    Bacterial blight, which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating rice diseases worldwide. The development and use of disease-resistant cultivars have been the most effective strategy to control bacterial blight. Identifying the genes mediating bacterial blight resistance is a prerequisite for breeding cultivars with broad-spectrum and durable resistance. We herein describe a genome-wide association study involving 172 diverse Oryza sativa ssp. indica accessions to identify loci influencing the resistance to representative strains of six Xoo races. Twelve resistance loci containing 121 significantly associated signals were identified using 317,894 single nucleotide polymorphisms, which explained 13.3–59.9% of the variability in lesion length caused by Xoo races P1, P6, and P9a. Two hotspot regions (L11 and L12) were located within or nearby two cloned R genes (xa25 and Xa26) and one fine-mapped R gene (Xa4). Our results confirmed the relatively high resolution of genome-wide association studies. Moreover, we detected novel significant associations on chromosomes 2, 3, and 6–10. Haplotype analyses of xa25, the Xa26 paralog (MRKc; LOC_Os11g47290), and a Xa4 candidate gene (LOC_11g46870) revealed differences in bacterial blight resistance among indica subgroups. These differences were responsible for the observed variations in lesion lengths resulting from infections by Xoo races P1 and P9a. Our findings may be relevant for future studies involving bacterial blight resistance gene cloning, and provide insights into the genetic basis for bacterial blight resistance in indica rice, which may be useful for knowledge-based crop improvement. PMID:28355306

  12. The Composition and Spatial Patterns of Bacterial Virulence Factors and Antibiotic Resistance Genes in 19 Wastewater Treatment Plants

    PubMed Central

    Zhang, Bing; Xia, Yu; Wen, Xianghua; Wang, Xiaohui; Yang, Yunfeng; Zhou, Jizhong; Zhang, Yu

    2016-01-01

    Bacterial pathogenicity and antibiotic resistance are of concern for environmental safety and public health. Accumulating evidence suggests that wastewater treatment plants (WWTPs) are as an important sink and source of pathogens and antibiotic resistance genes (ARGs). Virulence genes (encoding virulence factors) are good indicators for bacterial pathogenic potentials. To achieve a comprehensive understanding of bacterial pathogenic potentials and antibiotic resistance in WWTPs, bacterial virulence genes and ARGs in 19 WWTPs covering a majority of latitudinal zones of China were surveyed by using GeoChip 4.2. A total of 1610 genes covering 13 virulence factors and 1903 genes belonging to 11 ARG families were detected respectively. The bacterial virulence genes exhibited significant spatial distribution patterns of a latitudinal biodiversity gradient and a distance-decay relationship across China. Moreover, virulence genes tended to coexist with ARGs as shown by their strongly positive associations. In addition, key environmental factors shaping the overall virulence gene structure were identified. This study profiles the occurrence, composition and distribution of virulence genes and ARGs in current WWTPs in China, and uncovers spatial patterns and important environmental variables shaping their structure, which may provide the basis for further studies of bacterial virulence factors and antibiotic resistance in WWTPs. PMID:27907117

  13. Seasonal variations in bacterial communities and antibiotic-resistant strains associated with green bottle flies (Diptera: Calliphoridae).

    PubMed

    Wei, Ting; Ishida, Ryuichi; Miyanaga, Kazuhiko; Tanji, Yasunori

    2014-05-01

    Green bottle flies occur frequently around human environments in Japan. Many species of green bottle flies have been studied with regard to their importance in forensic examinations or clinical therapies, but the bacterial communities associated with this group of flies have not been comprehensively investigated. In this research, 454 pyrosequencing was used to reveal the bacterial communities in green bottle flies collected in different seasons. Meanwhile, the bacteria were screened with selective media and tested for antibiotic susceptibility. Samples collected in three different seasons harbored distinctive bacterial communities. The predominant genera associated with green bottles flies were Staphylococcus in spring, Ignatzschineria in summer, and Vagococcus, Dysgonomonas, and an unclassified Acetobacteraceae in autumn. An upward trend in bacterial community diversity was observed from spring to autumn. Changes in climatic conditions could be the cause of these seasonal variations in fly-associated bacterial communities. The species of isolated antibiotic-resistant bacteria also differed across seasons, but it was difficult to correlate seasonal changes in antibiotic-resistant bacteria with changes in whole communities. A number of multiple-antibiotic-resistant bacteria were isolated, and some of these strains were closely affiliated with pathogens such as Enterococcus faecalis and Enterococcus faecium, which could cause serious threats to public health. Overall, this research provided us with information about the composition and seasonality of bacterial communities in green bottle flies, and highlighted the risks of fly-mediated dissemination of antibiotic-resistant pathogens.

  14. The Composition and Spatial Patterns of Bacterial Virulence Factors and Antibiotic Resistance Genes in 19 Wastewater Treatment Plants.

    PubMed

    Zhang, Bing; Xia, Yu; Wen, Xianghua; Wang, Xiaohui; Yang, Yunfeng; Zhou, Jizhong; Zhang, Yu

    2016-01-01

    Bacterial pathogenicity and antibiotic resistance are of concern for environmental safety and public health. Accumulating evidence suggests that wastewater treatment plants (WWTPs) are as an important sink and source of pathogens and antibiotic resistance genes (ARGs). Virulence genes (encoding virulence factors) are good indicators for bacterial pathogenic potentials. To achieve a comprehensive understanding of bacterial pathogenic potentials and antibiotic resistance in WWTPs, bacterial virulence genes and ARGs in 19 WWTPs covering a majority of latitudinal zones of China were surveyed by using GeoChip 4.2. A total of 1610 genes covering 13 virulence factors and 1903 genes belonging to 11 ARG families were detected respectively. The bacterial virulence genes exhibited significant spatial distribution patterns of a latitudinal biodiversity gradient and a distance-decay relationship across China. Moreover, virulence genes tended to coexist with ARGs as shown by their strongly positive associations. In addition, key environmental factors shaping the overall virulence gene structure were identified. This study profiles the occurrence, composition and distribution of virulence genes and ARGs in current WWTPs in China, and uncovers spatial patterns and important environmental variables shaping their structure, which may provide the basis for further studies of bacterial virulence factors and antibiotic resistance in WWTPs.

  15. Prevalence of plasmid mediated pesticide resistant bacterial assemblages in crop fields.

    PubMed

    Umamaheswari, S; Murali, M

    2010-11-01

    Three crop fields namely paddy sugarcane and tomato exposed to bavistin [Methyl (1H-benzimidazol-2-yl) carbomate], monocrotophos[Dimethyl(E)-1-methyl-2-(methyl-carbamoyl) vinyl phosphate] and kinado plus [(EZ)-2-chloro-3-dimethoxyphosphinoyloxy-X1, X1-diethylbut-2-enamide], respectively were chosen for the present investigation to know the bacterial population and degradation of pesticides. The chemical nature of the soil and water samples from the pesticide contaminated fields was analysed along with counting of the total heterotrophic bacteria (THB), Staphylococci and Enterococcci population. Mean calcium, phosphate and biological oxygen demand were maximum in tomato field water Field water recorded maximum phophate and silicate content, whereas, sugarcane field water elicited maximum dissolved oxygen content. On the other hand, available phosphate and exchangeable potassium were maximum is sugarcane field soil. Significant variations in the bacterial population were evident between the treatments in sugarcane field soil and tomato field water exposed to monocrotophos and kinado plus, respectively In addition, significant variations between THB, Staphlyococci and Enterococci population were also evinced in both the sugarcane andtomato fields. The dominant pesticide resistant bacteria, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeuroginosa harboured plasmids and the resistant trait observed were found to be plasmid borne.

  16. Gene silencing using the recessive rice bacterial blight resistance gene xa13 as a new paradigm in plant breeding.

    PubMed

    Li, Changyan; Wei, Jing; Lin, Yongjun; Chen, Hao

    2012-05-01

    Resistant germplasm resources are valuable for developing resistant varieties in agricultural production. However, recessive resistance genes are usually overlooked in hybrid breeding. Compared with dominant traits, however, they may confer resistance to different pathogenic races or pest biotypes with different mechanisms of action. The recessive rice bacterial blight resistance gene xa13, also involved in pollen development, has been cloned and its resistance mechanism has been recently characterized. This report describes the conversion of bacterial blight resistance mediated by the recessive xa13 gene into a dominant trait to facilitate its use in a breeding program. This was achieved by knockdown of the corresponding dominant allele Xa13 in transgenic rice using recently developed artificial microRNA technology. Tissue-specific promoters were used to exclude most of the expression of artificial microRNA in the anther to ensure that Xa13 functioned normally during pollen development. A battery of highly bacterial blight resistant transgenic plants with normal seed setting rates were acquired, indicating that highly specific gene silencing had been achieved. Our success with xa13 provides a paradigm that can be adapted to other recessive resistance genes.

  17. Transgenic resistance confers effective field level control of bacterial spot disease in tomato.

    PubMed

    Horvath, Diana M; Stall, Robert E; Jones, Jeffrey B; Pauly, Michael H; Vallad, Gary E; Dahlbeck, Doug; Staskawicz, Brian J; Scott, John W

    2012-01-01

    We investigated whether lines of transgenic tomato (Solanum lycopersicum) expressing the Bs2 resistance gene from pepper, a close relative of tomato, demonstrate improved resistance to bacterial spot disease caused by Xanthomonas species in replicated multi-year field trials under commercial type growing conditions. We report that the presence of the Bs2 gene in the highly susceptible VF 36 background reduced disease to extremely low levels, and VF 36-Bs2 plants displayed the lowest disease severity amongst all tomato varieties tested, including commercial and breeding lines with host resistance. Yields of marketable fruit from transgenic lines were typically 2.5 times that of the non-transformed parent line, but varied between 1.5 and 11.5 fold depending on weather conditions and disease pressure. Trials were conducted without application of any copper-based bactericides, presently in wide use despite negative impacts on the environment. This is the first demonstration of effective field resistance in a transgenic genotype based on a plant R gene and provides an opportunity for control of a devastating pathogen while eliminating ineffective copper pesticides.

  18. Clinical treatment of pandrug-resistant bacterial infection consulted by clinical pharmacist

    PubMed Central

    Zhi-Wen, Yang; Yan-Li, Zhang; Man, Yuan; Wei-Jun, Fang

    2015-01-01

    Objective Pandrug-resistant (PDR) bacterial infections are associated with considerable prolongation of hospitalization and mortality in clinical practice. Method This case-series study was conducted during a 3-year period from 2011 to 2013. A total of 30 PDR patients consulted by clinical pharmacist were recorded to evaluate the anti-infection treatment. Results All isolates of PDR bacteria from patients were identified as pan-drug resistant acine-tobacter baumannii (63.3%), pan-drug resistant klebsiella pneumonia (20.0%), and pandrug-resistant pseudomonas aeruginosa (16.7%). Of the 30 patients, 96.7% therapeutic regimens supposed by clinical pharmacists were applied to treat the infectious patients up to 82.8% clinical cure rates. 30 patients completed the prescribed treatment, of which 19 underwent monotherapy that the clinical cure rate was 78.9%, and 10 underwent combination therapy that the clinical cure rate was 90.0%. In the following therapy, doxycycline, cefoperazone shubatan and amikacin have the certain effect on anti-infection therapy. Combination therapy combined with doxycycline was better treatment option for PDR infectious patients. Conclusion In a word, it appears to be effective for the successful therapy of PDR infections upon tetracyclines administration. PMID:27134538

  19. Transgenic Resistance Confers Effective Field Level Control of Bacterial Spot Disease in Tomato

    PubMed Central

    Horvath, Diana M.; Stall, Robert E.; Jones, Jeffrey B.; Pauly, Michael H.; Vallad, Gary E.; Dahlbeck, Doug; Staskawicz, Brian J.; Scott, John W.

    2012-01-01

    We investigated whether lines of transgenic tomato (Solanum lycopersicum) expressing the Bs2 resistance gene from pepper, a close relative of tomato, demonstrate improved resistance to bacterial spot disease caused by Xanthomonas species in replicated multi-year field trials under commercial type growing conditions. We report that the presence of the Bs2 gene in the highly susceptible VF 36 background reduced disease to extremely low levels, and VF 36-Bs2 plants displayed the lowest disease severity amongst all tomato varieties tested, including commercial and breeding lines with host resistance. Yields of marketable fruit from transgenic lines were typically 2.5 times that of the non-transformed parent line, but varied between 1.5 and 11.5 fold depending on weather conditions and disease pressure. Trials were conducted without application of any copper-based bactericides, presently in wide use despite negative impacts on the environment. This is the first demonstration of effective field resistance in a transgenic genotype based on a plant R gene and provides an opportunity for control of a devastating pathogen while eliminating ineffective copper pesticides. PMID:22870280

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

    PubMed Central

    SOARES, Geisla Mary Silva; FIGUEIREDO, Luciene Cristina; FAVERI, Marcelo; CORTELLI, Sheila Cavalca; DUARTE, Poliana Mendes; FERES, Magda

    2012-01-01

    Antibiotics are important adjuncts in the treatment of infectious diseases, including periodontitis. The most severe criticisms to the indiscriminate use of these drugs are their side effects and, especially, the development of bacterial resistance. The knowledge of the biological mechanisms involved with the antibiotic usage would help the medical and dental communities to overcome these two problems. Therefore, the aim of this manuscript was to review the mechanisms of action of the antibiotics most commonly used in the periodontal treatment (i.e. penicillin, tetracycline, macrolide and metronidazole) and the main mechanisms of bacterial resistance to these drugs. Antimicrobial resistance can be classified into three groups: intrinsic, mutational and acquired. Penicillin, tetracycline and erythromycin are broad-spectrum drugs, effective against gram-positive and gram-negative microorganisms. Bacterial resistance to penicillin may occur due to diminished permeability of the bacterial cell to the antibiotic; alteration of the penicillin-binding proteins, or production of β-lactamases. However, a very small proportion of the subgingival microbiota is resistant to penicillins. Bacteria become resistant to tetracyclines or macrolides by limiting their access to the cell, by altering the ribosome in order to prevent effective binding of the drug, or by producing tetracycline/macrolide-inactivating enzymes. Periodontal pathogens may become resistant to these drugs. Finally, metronidazole can be considered a prodrug in the sense that it requires metabolic activation by strict anaerobe microorganisms. Acquired resistance to this drug has rarely been reported. Due to these low rates of resistance and to its high activity against the gram-negative anaerobic bacterial species, metronidazole is a promising drug for treating periodontal infections. PMID:22858695

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

    PubMed

    Soares, Geisla Mary Silva; Figueiredo, Luciene Cristina; Faveri, Marcelo; Cortelli, Sheila Cavalca; Duarte, Poliana Mendes; Feres, Magda

    2012-01-01

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

  2. Evaluation of cotton burdock (Arctium tomentosum Mill.) responses to multi-metal exposure.

    PubMed

    Al Harbawee, Waad E Q; Kluchagina, Alina N; Anjum, Naser A; Bashmakov, Dmitry I; Lukatkin, Alexander S; Pereira, Eduarda

    2017-02-01

    Plants have immense potential for their use in the minimization of emerging environmental pollution issues. Under simulated laboratory conditions, this work investigated the growth and biochemical responses of 14-day-old cotton burdock (Arctium tomentosum Mill.) seedlings to the body burdens of multi-metals including Pb, Cu, Ni, and Zn (1.0 μM-10 mM). Biochemical traits (superoxide generation, lipid peroxidation, content of total peroxides), growth traits (axial organs growth, dry weight accumulation, leaf area), and also metal body burdens varied with types and concentrations of metals. Results indicated a significant tolerance of A. tomentosum to multi-metals that can be implicated for its potential role in the metal phytoremediation programs.

  3. Increasing Incidence of Multidrug Resistance Among Cystic Fibrosis Respiratory Bacterial Isolates.

    PubMed

    Rutter, W Cliff; Burgess, Donna R; Burgess, David S

    2017-01-01

    Pseudomonas aeruginosa and Staphylococcus aureus are common pathogens in cystic fibrosis (CF) patients with increasing multidrug resistance (MDR). This study characterized antimicrobial susceptibility trends among organisms isolated from the respiratory tract of CF patients. Microbiological culture and sensitivity results for all CF patients were collected from January 2010 through December 2014. Minimum inhibitory concentrations were obtained using Phoenix(®) and Etest(®) methods. Clinical and Laboratory Standards Institute guidelines were used to remove duplicate isolates and develop antimicrobial susceptibility reports. MDR was defined as resistance to one agent in three or more antibiotic classes or oxacillin resistance in S. aureus. Overall, 542 bacterial isolates from 376 cultures were analyzed for trends. P. aeruginosa (41%), S. aureus (40%), and Stenotrophomonas maltophilia (8%) were the most commonly isolated organisms. Multidrug-resistant organism isolation increased from 39% to 49% (r = 0.76, p = 0.13), while representing 47.6% of all isolates. Multidrug-resistant P. aeruginosa incidence increased each year from 26% to 43% (r = 0.89, p = 0.046), while P. aeruginosa isolation decreased from 47% to 38% over the study period (r = -0.93, p = 0.02). MRSA accounted for 62.6% of all S. aureus isolated, while overall multidrug-resistant S. aureus incidence was 73.1% in all cultures. MDR among common pathogens in CF continues to increase. Empiric therapy for CF exacerbations should be targeted to previous antimicrobial susceptibility, and P. aeruginosa and S. aureus should be empirically covered.

  4. Arabidopsis dual resistance proteins, both RPS4 and RRS1, are required for resistance to bacterial wilt in transgenic Brassica crops.

    PubMed

    Narusaka, Mari; Hatakeyama, Katsunori; Shirasu, Ken; Narusaka, Yoshihiro

    2014-01-01

    Bacterial wilt phytopathogen Ralstonia solanacearum is a serious soil-borne disease that attacks several economically important plants worldwide, including Brassicaceae. Previous studies indicate that recognition of avirulence (Avr)-effector PopP2 by resistance (R) protein, RRS1-R, and physical interaction between RRS1-R and PopP2 in the nucleus are required for resistance. Of late, we showed that a pair of Arabidopsis thaliana TIR-NLR proteins, RRS1 and RPS4, function together in disease resistance against multiple pathogen isolates. Here, we report that dual R proteins, RRS1 and RPS4, from A. thaliana ecotype Wassilewskija confer resistance to bacterial wilt in transgenic Brassica crops. For practical applications, this finding may provide a new strategy for developing disease resistant plants that express R genes from other plants.

  5. ARG-ANNOT, a New Bioinformatic Tool To Discover Antibiotic Resistance Genes in Bacterial Genomes

    PubMed Central

    Gupta, Sushim Kumar; Padmanabhan, Babu Roshan; Diene, Seydina M.; Lopez-Rojas, Rafael; Kempf, Marie; Landraud, Luce

    2014-01-01

    ARG-ANNOT (Antibiotic Resistance Gene-ANNOTation) is a new bioinformatic tool that was created to detect existing and putative new antibiotic resistance (AR) genes in bacterial genomes. ARG-ANNOT uses a local BLAST program in Bio-Edit software that allows the user to analyze sequences without a Web interface. All AR genetic determinants were collected from published works and online resources; nucleotide and protein sequences were retrieved from the NCBI GenBank database. After building a database that includes 1,689 antibiotic resistance genes, the software was tested in a blind manner using 100 random sequences selected from the database to verify that the sensitivity and specificity were at 100% even when partial sequences were queried. Notably, BLAST analysis results obtained using the rmtF gene sequence (a new aminoglycoside-modifying enzyme gene sequence that is not included in the database) as a query revealed that the tool was able to link this sequence to short sequences (17 to 40 bp) found in other genes of the rmt family with significant E values. Finally, the analysis of 178 Acinetobacter baumannii and 20 Staphylococcus aureus genomes allowed the detection of a significantly higher number of AR genes than the Resfinder gene analyzer and 11 point mutations in target genes known to be associated with AR. The average time for the analysis of a genome was 3.35 ± 0.13 min. We have created a concise database for BLAST using a Bio-Edit interface that can detect AR genetic determinants in bacterial genomes and can rapidly and easily discover putative new AR genetic determinants. PMID:24145532

  6. Violacein as a genetically-controlled, enzymatically amplified and photobleaching-resistant chromophore for optoacoustic bacterial imaging

    PubMed Central

    Jiang, Yuanyuan; Sigmund, Felix; Reber, Josefine; Luís Deán-Ben, Xosé; Glasl, Sarah; Kneipp, Moritz; Estrada, Héctor; Razansky, Daniel; Ntziachristos, Vasilis; Westmeyer, Gil G.

    2015-01-01

    There is growing interest in genetically expressed reporters for in vivo studies of bacterial colonization in the context of infectious disease research, studies of the bacterial microbiome or cancer imaging and treatment. To empower non-invasive high-resolution bacterial tracking with deep tissue penetration, we herein use the genetically controlled biosynthesis of the deep-purple pigment Violacein as a photobleaching-resistant chromophore label for in vivo optoacoustic (photoacoustic) imaging in the near-infrared range. We demonstrate that Violacein-producing bacteria can be imaged with high contrast-to-noise in strongly vascularized xenografted murine tumors and further observe that Violacein shows anti-tumoral activity. Our experiments thus identify Violacein as a robust bacterial label for non-invasive optoacoustic imaging with high potential for basic research and future theranostic applications in bacterial tumor targeting. PMID:26091543

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

    PubMed

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

    2016-10-01

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

  8. Tetracycline Antibiotics: Mode of Action, Applications, Molecular Biology, and Epidemiology of Bacterial Resistance

    PubMed Central

    Chopra, Ian; Roberts, Marilyn

    2001-01-01

    Tetracyclines were discovered in the 1940s and exhibited activity against a wide range of microorganisms including gram-positive and gram-negative bacteria, chlamydiae, mycoplasmas, rickettsiae, and protozoan parasites. They are inexpensive antibiotics, which have been used extensively in the prophlylaxis and therapy of human and animal infections and also at subtherapeutic levels in animal feed as growth promoters. The first tetracycline-resistant bacterium, Shigella dysenteriae, was isolated in 1953. Tetracycline resistance now occurs in an increasing number of pathogenic, opportunistic, and commensal bacteria. The presence of tetracycline-resistant pathogens limits the use of these agents in treatment of disease. Tetracycline resistance is often due to the acquisition of new genes, which code for energy-dependent efflux of tetracyclines or for a protein that protects bacterial ribosomes from the action of tetracyclines. Many of these genes are associated with mobile plasmids or transposons and can be distinguished from each other using molecular methods including DNA-DNA hybridization with oligonucleotide probes and DNA sequencing. A limited number of bacteria acquire resistance by mutations, which alter the permeability of the outer membrane porins and/or lipopolysaccharides in the outer membrane, change the regulation of innate efflux systems, or alter the 16S rRNA. New tetracycline derivatives are being examined, although their role in treatment is not clear. Changing the use of tetracyclines in human and animal health as well as in food production is needed if we are to continue to use this class of broad-spectrum antimicrobials through the present century. PMID:11381101

  9. How fitness reduced, antimicrobial resistant bacteria survive and spread: a multiple pig-multiple bacterial strain model.

    PubMed

    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. Application of Targeted Molecular and Material Property Optimization to Bacterial Attachment-Resistant (Meth)acrylate Polymers.

    PubMed

    Adlington, Kevin; Nguyen, Nam T; Eaves, Elizabeth; Yang, Jing; Chang, Chien-Yi; Li, Jianing; Gower, Alexandra L; Stimpson, Amy; Anderson, Daniel G; Langer, Robert; Davies, Martyn C; Hook, Andrew L; Williams, Paul; Alexander, Morgan R; Irvine, Derek J

    2016-09-12

    Developing medical devices that resist bacterial attachment and subsequent biofilm formation is highly desirable. In this paper, we report the optimization of the molecular structure and thus material properties of a range of (meth)acrylate copolymers which contain monomers reported to deliver bacterial resistance to surfaces. This optimization allows such monomers to be employed within novel coatings to reduce bacterial attachment to silicone urinary catheters. We show that the flexibility of copolymers can be tuned to match that of the silicone catheter substrate, by copolymerizing these polymers with a lower Tg monomer such that it passes the flexing fatigue tests as coatings upon catheters, that the homopolymers failed. Furthermore, the Tg values of the copolymers are shown to be readily estimated by the Fox equation. The bacterial resistance performance of these copolymers were typically found to be better than the neat silicone or a commercial silver containing hydrogel surface, when the monomer feed contained only 25 v% of the "hit" monomer. The method of initiation (either photo or thermal) was shown not to affect the bacterial resistance of the copolymers. Optimized synthesis conditions to ensure that the correct copolymer composition and to prevent the onset of gelation are detailed.

  11. Bacterial cell-to-cell signaling promotes the evolution of resistance to parasitic bacteriophages.

    PubMed

    Moreau, Pierre; Diggle, Stephen P; Friman, Ville-Petri

    2017-03-01

    The evolution of host-parasite interactions could be affected by intraspecies variation between different host and parasite genotypes. Here we studied how bacterial host cell-to-cell signaling affects the interaction with parasites using two bacteria-specific viruses (bacteriophages) and the host bacterium Pseudomonas aeruginosa that communicates by secreting and responding to quorum sensing (QS) signal molecules. We found that a QS-signaling proficient strain was able to evolve higher levels of resistance to phages during a short-term selection experiment. This was unlikely driven by demographic effects (mutation supply and encounter rates), as nonsignaling strains reached higher population densities in the absence of phages in our selective environment. Instead, the evolved nonsignaling strains suffered relatively higher growth reduction in the absence of the phage, which could have constrained the phage resistance evolution. Complementation experiments with synthetic signal molecules showed that the Pseudomonas quinolone signal (PQS) improved the growth of nonsignaling bacteria in the presence of a phage, while the activation of las and rhl quorum sensing systems had no effect. Together, these results suggest that QS-signaling can promote the evolution of phage resistance and that the loss of QS-signaling could be costly in the presence of phages. Phage-bacteria interactions could therefore indirectly shape the evolution of intraspecies social interactions and PQS-mediated virulence in P. aeruginosa.

  12. Antimicrobial Resistance in the Intensive Care Unit: A Focus on Gram-Negative Bacterial Infections.

    PubMed

    MacVane, Shawn H

    2017-01-01

    Bacterial infections are a frequent cause of hospitalization, and nosocomial infections are an increasingly common condition, particularly within the acute/critical care setting. Infection control practices and new antimicrobial development have primarily focused on gram-positive bacteria; however, in recent years, the incidence of infections caused by gram-negative bacteria has risen considerably in intensive care units. Infections caused by multidrug-resistant (MDR) gram-negative organisms are associated with high morbidity and mortality, with significant direct and indirect costs resulting from prolonged hospitalizations due to antibiotic treatment failures. Of particular concern is the increasing prevalence of antimicrobial resistance to β-lactam antibiotics (including carbapenems) among Pseudomonas aeruginosa and Acinetobacter baumannii and, recently, among pathogens of the Enterobacteriaceae family. Treatment options for infections caused by these pathogens are limited. Antimicrobial stewardship programs focus on optimizing the appropriate use of currently available antimicrobial agents with the goals of improving outcomes for patients with infections caused by MDR gram-negative organisms, slowing the progression of antimicrobial resistance, and reducing hospital costs. Newly approved treatment options are available, such as β-lactam/β-lactamase inhibitor combinations, which significantly extend the armamentarium against MDR gram-negative bacteria.

  13. Tailored silica-antibiotic nanoparticles: overcoming bacterial resistance with low cytotoxicity.

    PubMed

    Capeletti, Larissa Brentano; de Oliveira, Luciane França; Gonçalves, Kaliandra de Almeida; de Oliveira, Jessica Fernanda Affonso; Saito, Ângela; Kobarg, Jörg; dos Santos, João Henrique Zimnoch; Cardoso, Mateus Borba

    2014-07-01

    New and more aggressive antibiotic resistant bacteria arise at an alarming rate and represent an ever-growing challenge to global health care systems. Consequently, the development of new antimicrobial agents is required to overcome the inefficiency of conventional antibiotics and bypass treatment limitations related to these pathologies. In this study, we present a synthesis protocol, which was able to entrap tetracycline antibiotic into silica nanospheres. Bactericidal efficacy of these structures was tested against bacteria that were susceptible and resistant to antibiotics. For nonresistant bacteria, our composite had bactericidal efficiency comparable to that of free-tetracycline. On the other hand, the synthesized composites were able to avoid bacterial growth of resistant bacteria while free-tetracycline has shown no significant bactericidal effect. Finally, we have investigated the cytotoxicity of these nanoparticles against mammalian cells to check any possible poisoning effect. It was found that these nanospheres are not apoptosis-inducers and only a reduction on the cell replication rate was seen when compared to the control without nanoparticles.

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

    PubMed

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

    2014-07-30

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

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

    PubMed Central

    Gonsu, Hortense Kamga; Koulla-Shiro, Sinata

    2016-01-01

    Introduction. Community-acquired urinary tract infections (CAUTIs) are usually treated empirically. Geographical variations in etiologic agents and their antibiotic sensitivity patterns are common. Knowledge of antibiotic resistance trends is important for improving evidence-based recommendations for empirical treatment of UTIs. Our aim was to determine the major bacterial etiologies of CAUTIs and their antibiotic resistance patterns in a cosmopolitan area of Cameroon for comparison with prescription practices of local physicians. Methods. We performed a cross-sectional descriptive study at two main hospitals in Yaoundé, collecting a clean-catch mid-stream urine sample from 92 patients having a clinical diagnosis of UTI. The empirical antibiotherapy was noted, and identification of bacterial species was done on CLED agar; antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method. Results. A total of 55 patients had samples positive for a UTI. Ciprofloxacin and amoxicillin/clavulanic acid were the most empirically prescribed antibiotics (30.9% and 23.6%, resp.); bacterial isolates showed high prevalence of resistance to both compounds. Escherichia coli (50.9%) was the most common pathogen, followed by Klebsiella pneumoniae (16.4%). Prevalence of resistance for ciprofloxacin was higher compared to newer quinolones. Conclusions. E. coli and K. pneumoniae were the predominant bacterial etiologies; the prevalence of resistance to commonly prescribed antibiotics was high. PMID:27667998

  16. Small-plasmid-mediated antibiotic resistance is enhanced by increases in plasmid copy number and bacterial fitness.

    PubMed

    San Millan, Alvaro; Santos-Lopez, Alfonso; Ortega-Huedo, Rafael; Bernabe-Balas, Cristina; Kennedy, Sean P; Gonzalez-Zorn, Bruno

    2015-01-01

    Plasmids play a key role in the horizontal spread of antibiotic resistance determinants among bacterial pathogens. When an antibiotic resistance plasmid arrives in a new bacterial host, it produces a fitness cost, causing a competitive disadvantage for the plasmid-bearing bacterium in the absence of antibiotics. On the other hand, in the presence of antibiotics, the plasmid promotes the survival of the clone. The adaptations experienced by plasmid and bacterium in the presence of antibiotics during the first generations of coexistence will be crucial for the progress of the infection and the maintenance of plasmid-mediated resistance once the treatment is over. Here we developed a model system using the human pathogen Haemophilus influenzae carrying the small plasmid pB1000 conferring resistance to β-lactam antibiotics to investigate host and plasmid adaptations in the course of a simulated ampicillin therapy. Our results proved that plasmid-bearing clones compensated for the fitness disadvantage during the first 100 generations of plasmid-host adaptation. In addition, ampicillin treatment was associated with an increase in pB1000 copy number. The augmentation in both bacterial fitness and plasmid copy number gave rise to H. influenzae populations with higher ampicillin resistance levels. In conclusion, we show here that the modulations in bacterial fitness and plasmid copy number help a plasmid-bearing bacterium to adapt during antibiotic therapy, promoting both the survival of the host and the spread of the plasmid.

  17. Characterization of copper-resistant bacteria and bacterial communities from copper-polluted agricultural soils of central Chile

    PubMed Central

    2012-01-01

    Background Copper mining has led to Cu pollution in agricultural soils. In this report, the effects of Cu pollution on bacterial communities of agricultural soils from Valparaiso region, central Chile, were studied. Denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA genes was used for the characterization of bacterial communities from Cu-polluted and non-polluted soils. Cu-resistant bacterial strains were isolated from Cu-polluted soils and characterized. Results DGGE showed a similar high number of bands and banding pattern of the bacterial communities from Cu-polluted and non-polluted soils. The presence of copA genes encoding the multi-copper oxidase that confers Cu-resistance in bacteria was detected by PCR in metagenomic DNA from the three Cu-polluted soils, but not in the non-polluted soil. The number of Cu-tolerant heterotrophic cultivable bacteria was significantly higher in Cu-polluted soils than in the non-polluted soil. Ninety two Cu-resistant bacterial strains were isolated from three Cu-polluted agricultural soils. Five isolated strains showed high resistance to copper (MIC ranged from 3.1 to 4.7 mM) and also resistance to other heavy metals. 16S rRNA gene sequence analyses indicate that these isolates belong to the genera Sphingomonas, Stenotrophomonas and Arthrobacter. The Sphingomonas sp. strains O12, A32 and A55 and Stenotrophomonas sp. C21 possess plasmids containing the Cu-resistance copA genes. Arthrobacter sp. O4 possesses the copA gene, but plasmids were not detected in this strain. The amino acid sequences of CopA from Sphingomonas isolates (O12, A32 and A55), Stenotrophomonas strain (C21) and Arthrobacter strain (O4) are closely related to CopA from Sphingomonas, Stenotrophomonas and Arthrobacter strains, respectively. Conclusions This study suggests that bacterial communities of agricultural soils from central Chile exposed to long-term Cu-pollution have been adapted by acquiring Cu genetic determinants. Five bacterial isolates

  18. Adaptation of the cecal bacterial microbiome of growing pigs in response to resistant starch type 4.

    PubMed

    Metzler-Zebeli, Barbara U; Schmitz-Esser, Stephan; Mann, Evelyne; Grüll, Dietmar; Molnar, Timea; Zebeli, Qendrim

    2015-12-01

    Resistant starch (RS) exacerbates health benefits on the host via modulation of the gut bacterial community. By far, these effects have been less well explored for RS of type 4. This study aimed at gaining a community-wide insight into the impact of enzymatically modified starch (EMS) on the cecal microbiota and hindgut fermentation in growing pigs. Castrated male pigs (n = 12/diet; 29-kg body weight) were fed diets with either 70% EMS or control starch for 10 days. The bacterial profile of each cecal sample was determined by sequencing of the V345 region of the 16S rRNA gene using the Illumina MiSeq platform. EMS diet reduced short-chain fatty acid concentrations in cecum and proximal colon compared to the control diet. Linear discriminant analyses and K means clustering indicated diet-specific cecal community profiles, whereby diversity and species richness were not different among diets. Pigs showed host-specific variation in their most abundant phyla, Firmicutes (55%), Proteobacteria (35%), and Bacteroidetes (10%). The EMS diet decreased abundance of Ruminococcus, Parasutterella, Bilophila, Enterococcus, and Lactobacillus operational taxonomic units (OTU), whereas Meniscus and Actinobacillus OTU were increased compared to those with the control diet (P < 0.05). Quantitative PCR confirmed results for host effect on Enterobacteriaceae and diet effect on members of the Lactobacillus group. The presence of less cecal short-chain fatty acids and the imputed metabolic functions of the cecal microbiome suggested that EMS was less degradable for cecal bacteria than the control starch. The present EMS effects on the bacterial community profiles were different than the previously reported RS effects and can be linked to the chemical structure of EMS.

  19. Adaptation of the Cecal Bacterial Microbiome of Growing Pigs in Response to Resistant Starch Type 4

    PubMed Central

    Schmitz-Esser, Stephan; Mann, Evelyne; Grüll, Dietmar; Molnar, Timea; Zebeli, Qendrim

    2015-01-01

    Resistant starch (RS) exacerbates health benefits on the host via modulation of the gut bacterial community. By far, these effects have been less well explored for RS of type 4. This study aimed at gaining a community-wide insight into the impact of enzymatically modified starch (EMS) on the cecal microbiota and hindgut fermentation in growing pigs. Castrated male pigs (n = 12/diet; 29-kg body weight) were fed diets with either 70% EMS or control starch for 10 days. The bacterial profile of each cecal sample was determined by sequencing of the V345 region of the 16S rRNA gene using the Illumina MiSeq platform. EMS diet reduced short-chain fatty acid concentrations in cecum and proximal colon compared to the control diet. Linear discriminant analyses and K means clustering indicated diet-specific cecal community profiles, whereby diversity and species richness were not different among diets. Pigs showed host-specific variation in their most abundant phyla, Firmicutes (55%), Proteobacteria (35%), and Bacteroidetes (10%). The EMS diet decreased abundance of Ruminococcus, Parasutterella, Bilophila, Enterococcus, and Lactobacillus operational taxonomic units (OTU), whereas Meniscus and Actinobacillus OTU were increased compared to those with the control diet (P < 0.05). Quantitative PCR confirmed results for host effect on Enterobacteriaceae and diet effect on members of the Lactobacillus group. The presence of less cecal short-chain fatty acids and the imputed metabolic functions of the cecal microbiome suggested that EMS was less degradable for cecal bacteria than the control starch. The present EMS effects on the bacterial community profiles were different than the previously reported RS effects and can be linked to the chemical structure of EMS. PMID:26431973

  20. Ethnomedicinal Cichorium intybus Seed Extracts: An Impending Preparation against Multidrug Resistant Bacterial Pathogens

    PubMed Central

    Rahman, Hazir; Khan, Usman Ali; Qasim, Muhammad; Muhammad, Noor; Khan, Muhammad Daud; Asif, Muhammad; Azizullah, Azizullah; Adnan, Muhammad; Murad, Waheed

    2016-01-01

    Background The present study was undertaken to analyze the phytochemical content and biological activity of Cichorium intybus seeds traditionally used in Charsadda, Pakistan against multidrug resistant (MDR) bacterial pathogens. Objectives This study explored the qualitative and quantitative antibacterial potential of C. intybus. Further qualitative analysis of phytochemical content was performed. Methods Cichorium intybus seed extracts were prepared in aqueous, chloroform, ethanol, and hexane separately. Results All the extracts of C. intybus seeds were screened for antibacterial activity and phytochemical content. Cichorium intybus seed extract showed considerable activity against MDR pathogenic bacteria. In the well diffusion method, aqueous extracts showed a higher zone of inhibition against Pseudomonas aeruginosa (16 mm ± 0.7 mm) and Acinetobacter baumannii (13 mm ± 0.5 mm), whereas chloroform, ethanol, and hexane extracts showed activity against P. aeruginosa (11 mm ± 0.3 mm, 12 mm ± 0.5 mm, and 11 mm ± 0 mm, respectively) as compared to Imipenem, a broad spectrum antibiotic. Minimum inhibitory concentration and minimum bactericidal concentration values for aqueous and ethanol extracts indicate that they were more effective against MDR bacteria. Phytochemical analysis revealed that aqueous and ethanol extracts were rich in alkaloids, carbohydrates, gallotannins, and triterpenoids, whereas chloroform and hexane extracts were more concentrated with phenolics, pseudotannins, saponins, and tannins. Cichorium intybus seed extract demonstrated potential activity against MDR human pathogenic bacteria. Conclusions The undertaken study has for the first time reported the effects of C. intybus seed extracts against MDR bacterial pathogens. Findings of the current study will be helpful for further elucidation of bioactive molecules for therapeutic use against MDR bacterial pathogens. PMID:28138372

  1. Close linkage of a blast resistance gene, Pias(t), with a bacterial leaf blight resistance gene, Xa1-as(t), in a rice cultivar 'Asominori'.

    PubMed

    Endo, Takashi; Yamaguchi, Masayuki; Kaji, Ryota; Nakagomi, Koji; Kataoka, Tomomori; Yokogami, Narifumi; Nakamura, Toshiki; Ishikawa, Goro; Yonemaru, Jun-Ichi; Nishio, Takeshi

    2012-12-01

    It has long been known that a bacterial leaf blight-resistant line in rice obtained from a crossing using 'Asominori' as a resistant parent also has resistance to blast, but a blast resistance gene in 'Asominori' has not been investigated in detail. In the present study, a blast resistance gene in 'Asominori', tentatively named Pias(t), was revealed to be located within 162-kb region between DNA markers YX4-3 and NX4-1 on chromosome 4 and to be linked with an 'Asominori' allele of the bacterial leaf blight resistance gene Xa1, tentatively named Xa1-as(t). An 'Asominori' allele of Pias(t) was found to be dominant and difference of disease severity between lines having the 'Asominori' allele of Pias(t) and those without it was 1.2 in disease index from 0 to 10. Pias(t) was also closely linked with the Ph gene controlling phenol reaction, suggesting the possibility of successful selection of blast resistance using the phenol reaction. Since blast-resistant commercial cultivars have been developed using 'Asominori' as a parent, Pias(t) is considered to be a useful gene in rice breeding for blast resistance.

  2. Development of robust biocompatible silicone with high resistance to protein adsorption and bacterial adhesion.

    PubMed

    Lin, Weifeng; Zhang, Juan; Wang, Zhen; Chen, Shengfu

    2011-05-01

    A new biocompatible silicone comprising a carboxybetaine (CB) ester analogue, 3-methacryloxypropyltris(trimethylsiloxy)silane (TRIS) and an organic silicone macromer (bis-α,ω-(methacryloxypropyl) polydimethylsiloxane) has been developed using photo-polymerisation. Following interfacial hydrolysis of the CB ester, the resulting zwitterionic material became significantly more hydrophilic and exhibited high resistance to both non-specific protein adsorption and bacterial adhesion. Moreover, the stability of these non-fouling properties was dramatically improved by using a slow and controlled rate of ester hydrolysis of the original protective hydrophobic matrix. The subsequent ability to maintain the original optical and mechanical properties of the bare silicone following surface activation makes this material an ideal candidate for preparing contact lenses and other medical devices.

  3. The role played by drug efflux pumps in bacterial multidrug resistance.

    PubMed

    Chitsaz, Mohsen; Brown, Melissa H

    2017-02-28

    Antimicrobial resistance is a current major challenge in chemotherapy and infection control. The ability of bacterial and eukaryotic cells to recognize and pump toxic compounds from within the cell to the environment before they reach their targets is one of the important mechanisms contributing to this phenomenon. Drug efflux pumps are membrane transport proteins that require energy to export substrates and can be selective for a specific drug or poly-specific that can export multiple structurally diverse drug compounds. These proteins can be classified into seven groups based on protein sequence homology, energy source and overall structure. Extensive studies on efflux proteins have resulted in a wealth of knowledge that has made possible in-depth understanding of the structures and mechanisms of action, substrate profiles, regulation and possible inhibition of many clinically important efflux pumps. This review focuses on describing known families of drug efflux pumps using examples that are well characterized structurally and/or biochemically.

  4. Classification Tree Method for Bacterial Source Tracking with Antibiotic Resistance Analysis Data

    PubMed Central

    Price, Bertram; Venso, Elichia A.; Frana, Mark F.; Greenberg, Joshua; Ware, Adam; Currey, Lee

    2006-01-01

    Various statistical classification methods, including discriminant analysis, logistic regression, and cluster analysis, have been used with antibiotic resistance analysis (ARA) data to construct models for bacterial source tracking (BST). We applied the statistical method known as classification trees to build a model for BST for the Anacostia Watershed in Maryland. Classification trees have more flexibility than other statistical classification approaches based on standard statistical methods to accommodate complex interactions among ARA variables. This article describes the use of classification trees for BST and includes discussion of its principal parameters and features. Anacostia Watershed ARA data are used to illustrate the application of classification trees, and we report the BST results for the watershed. PMID:16672492

  5. The bacterial paromomycin resistance gene, aphH, as a dominant selectable marker in Volvox carteri.

    PubMed

    Jakobiak, Thomas; Mages, Wolfgang; Scharf, Birgit; Babinger, Patrick; Stark, Klaus; Schmitt, Rüdiger

    2004-12-01

    The aminoglycoside antibiotic paromomycin that is highly toxic to the green alga Volvox carteri is efficiently inactivated by aminoglycoside 3'-phosphotransferase from Streptomyces rimosus. Therefore, we made constructs in which the bacterial aphH gene encoding this enzyme was combined with Volvox cis-regulatory elements in an attempt to develop a new dominant selectable marker--paromomycin resistance (PmR)--for use in Volvox nuclear transformation. The construct that provided the most efficient transformation was one in which aphH was placed between a chimeric promoter that was generated by fusing the Volvox hsp70 and rbcS3 promoters and the 3' UTR of the Volvox rbcS3 gene. When this plasmid was used in combination with a high-impact biolistic device, the frequency of stable PmR transformants ranged about 15 per 106 target cells. Due to rapid and sharp selection, PmR transformants were readily isolated after six days, which is half the time required for previously used markers. Co-transformation of an unselected marker ranged about 30%. The chimeric aphH gene was stably integrated into the Volvox genome, frequently as tandem multiple copies, and was expressed at a level that made selection of PmR transformants simple and unambiguous. This makes the engineered bacterial aphH gene an efficient dominant selection marker for the transformation and co-transformation of a broad range of V. carteri strains without the recurring need for using auxotrophic recipient strains.

  6. Development of candidate gene markers associated to common bacterial blight resistance in common bean.

    PubMed

    Shi, Chun; Yu, Kangfu; Xie, Weilong; Perry, Gregory; Navabi, Alireza; Pauls, K Peter; Miklas, Phillip N; Fourie, Deidré

    2012-11-01

    Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli (Xap), is a major yield-limiting factor of common bean (Phaseolus vulgaris L.) production around the world. Two major CBB-resistant quantitative trait loci (QTL), linked to the sequence characterized amplified region markers BC420 and SU91, are located at chromosomes 6 and 8, respectively. Using map-based cloning approach, four bacterial artificial chromosome (BAC) clones from the BC420-QTL locus and one BAC clone containing SU91 were sequenced by Roche 454 technique and subsequently assembled using merged assemblies from three different programs. Based on the quality of the assembly, only the sequences of BAC 32H6 and 4K7 were used for candidate gene marker (CGM) development and candidate gene (CG) selection. For the BC420-QTL locus, 21 novel genes were predicted in silico by FGENESH using Medicago gene model, whereas 16 genes were identified in the SU91-QTL locus. For each putative gene, one or more primer pairs were designed and tested in the contrasting near isogenic lines. Overall, six and nine polymorphic markers were found in the SU91- and BC420-QTL loci, respectively. Afterwards, association mapping was conducted in a breeding population of 395 dry bean lines to discover marker-trait associations. Two CGMs per each locus showed better association with CBB resistance than the BC420 and SU91 markers, which include BC420-CG10B and BC420-CG14 for BC420_QTL locus, and SU91-CG10 and SU91-CG11 for SU91_QTL locus. The strong associations between CBB resistance and the CGs 10 and 14 from BC420_QTL locus and the CGs 10 and 11 from SU91_QTL locus indicate that the genes 10 and 14 from the BC420 locus are potential CGs underlying the BC420_QTL locus, whereas the genes 10 and 11 from the SU91 locus are potential CGs underlying the SU91_QTL locus. The superiority of SU91-CG11 was further validated in a recombinant inbred line population Sanilac × OAC 09-3. Thus, co-dominant CGMs, BC420-CG14 and

  7. Bacteriophage therapy for membrane biofouling in membrane bioreactors and antibiotic-resistant bacterial biofilms.

    PubMed

    Bhattacharjee, Ananda Shankar; Choi, Jeongdong; Motlagh, Amir Mohaghegh; Mukherji, Sachiyo T; Goel, Ramesh

    2015-08-01

    To demonstrate elimination of bacterial biofilm on membranes to represent wastewater treatment as well as biofilm formed by antibiotic-resistant bacterial (ARB) to signify medical application, an antibiotic-resistant bacterium and its lytic bacteriophage were isolated from a full-scale wastewater treatment plant. Based on gram staining and complete 16 S rDNA sequencing, the isolated bacterium showed a more than 99% homology with Delftia tsuruhatensis, a gram-negative bacterium belonging to β-proteobacteria. The Delftia lytic phage's draft genome revealed the phage to be an N4-like phage with 59.7% G + C content. No transfer RNAs were detected for the phage suggesting that the phage is highly adapted to its host Delftia tsuruhatensis ARB-1 with regard to codon usage, and does not require additional tRNAs of its own. The gene annotation of the Delftia lytic phage found three different components of RNA polymerase (RNAP) in the genome, which is a typical characteristic of N4-like phages. The lytic phage specific to D. tsuruhatensis ARB-1 could successfully remove the biofilm formed by it on a glass slide. The water flux through the membrane of a prototype lab-scale membrane bioreactor decreased from 47 L/h m(2) to ∼15 L/h m(2) over 4 days due to a biofilm formed by D. tsuruhatensis ARB-1. However, the flux increased to 70% of the original after the lytic phage application. Overall, this research demonstrated phage therapy's great potential to solve the problem of membrane biofouling, as well as the problems posed by pathogenic biofilms in external wounds and on medical instruments.

  8. Aminomethyl Spectinomycins as Novel Therapeutics for Drug Resistant Respiratory Tract and Sexually Transmitted Bacterial Infections

    PubMed Central

    Madhura, Dora B.; Shcherbakov, Dimitri; Zheng, Zhong; Liu, Jiuyu; Abdelrahman, Yasser M.; Singh, Aman P.; Duscha, Stefan; Rathi, Chetan; Lee, Robin B.; Belland, Robert J.; Meibohm, Bernd; Rosch, Jason W.; Böttger, Erik C.; Lee, Richard E.

    2015-01-01

    The antibiotic spectinomycin is a potent inhibitor of bacterial protein synthesis with a unique mechanism of action and an excellent safety index, but it lacks antibacterial activity against most clinically important pathogens. A novel series of N-benzyl substituted 3'-(R)- 3'-aminomethyl-3'-hydroxy spectinomycins was developed based on a computational analysis of the aminomethyl spectinomycin binding site and structure guided synthesis. These compounds had ribosomal inhibition values comparable to spectinomycin but showed increased potency against common respiratory tract pathogens Streptococcus pneumoniae, Haemophilus influenzae, Legionella pneumophila, and Moraxella catarrhalis as well as the sexually transmitted bacteria Neisseria gonorrhoeae and Chlamydia trachomatis. Non-ribosome binding 3'-(S) isomers of the leads demonstrated weak inhibitory activity in in vitro protein translation assays and poor antibacterial activity, indicating that the antibacterial activity of the series remains on target. In addition to improved antibacterial potency, compounds also demonstrated no mammalian cytotoxicity, improved microsomal stability, and favorable pharmacokinetic properties in rats. The lead compound from the series, compound 1, exhibited excellent chemical stability, which was superior to spectinomycin and had no significant interaction with a panel of human receptors and drug metabolism enzymes suggesting low potential for adverse reactions or drug-drug interactions in vivo. Compound 1 was active in vitro against a panel of penicillin, macrolide, and cephalosporin resistant S. pneumoniae clinical isolates and cured mice of fatal pneumococcal pneumonia and sepsis at a dose of 5 mg/kg. Together, these studies indicate N-benzyl aminomethyl spectinomycins possess suitable properties for further development as novel antibacterial agents to treat drug resistant respiratory tract and sexually transmitted bacterial infections. PMID:25995221

  9. Resistance of a novel root canal sealer to bacterial ingress in vitro.

    PubMed

    Padachey, N; Patel, V; Santerre, P; Cvitkovitch, D; Lawrence, H P; Friedman, S

    2000-11-01

    A dentin-bonding root canal sealer (ZUT) has been developed, consisting of an experimental glass ionomer cement (KT-308) and an antimicrobial silver-containing zeolite (0.2% by weight). This in vitro study evaluated the ability of ZUT used with or without gutta-percha, to resist bacterial ingress of Enterococcus faecalis over a period of 90 days. Canals of 80 single-rooted teeth were prepared with apical patency and filled as follows (n = 10): KT-308 alone; KT-308 with a single gutta-percha cone (SCGP); ZUT alone; ZUT with SCGP; AH26 alone; AH26 with SCGP; positive control-no root canal filling; and negative control-no root canal filling, with the apices of this group sealed with C&B Metabond cement. Teeth were coated with nail polish except for the apical 2 mm, and each tooth was sealed in a 4-ml glass vial, with an 18-gauge needle inserted through the vial cover and bonded into the pulp chamber with C&B Metabond cement. After sterilization with 2.5 Mrad gamma-radiation, Brain Heart Infusion broth with phenol red was injected into each vial. An inoculum of E. faecalis was pipetted through the needle into the pulp chamber every 5 days, and the broth was monitored daily for color change and turbidity. When change occurred, the broth was cultured for growth of E. faecalis. Kaplan-Meier survival analysis and the log-rank test revealed no significant differences among the three sealers used. The presence of gutta-percha, however, significantly improved resistance to bacterial ingress through obturated root canals (X, p < 0.05). Under the conditions of this study, the hypothesized advantage of ZUT (0.2% zeolite) was not demonstrated.

  10. Characterization of rhizosphere fungi that mediate resistance in tomato against bacterial wilt disease.

    PubMed

    Jogaiah, Sudisha; Abdelrahman, Mostafa; Tran, Lam-Son Phan; Shin-ichi, Ito

    2013-09-01

    Plant immunization for resistance against a wide variety of phytopathogens is an effective strategy for plant disease management. Seventy-nine plant growth-promoting fungi (PGPFs) were isolated from rhizosphere soil of India. Among them, nine revealed saprophytic ability, root colonization, phosphate solubilization, IAA production, and plant growth promotion. Seed priming with four PGPFs exhibited early seedling emergence and enhanced vigour of a tomato cultivar susceptible to the bacterial wilt pathogen compared to untreated controls. Under greenhouse conditions, TriH_JSB27 and PenC_JSB41 treatments remarkably enhanced the vegetative and reproductive growth parameters. Maximum NPK uptake was noticed in TriH_JSB27-treated plants. A significant disease reduction of 57.3% against Ralstonia solanacearum was observed in tomato plants pretreated with TriH_JSB27. Furthermore, induction of defence-related enzymes and genes was observed in plants pretreated with PGPFs or inoculated with pathogen. The maximum phenylalanine ammonia lyase (PAL) activity (111U) was observed at 24h in seedlings treated with TriH_JSB27 and this activity was slightly reduced (99U) after pathogen inoculation. Activities of peroxidase (POX, 54U) and β-1,3-glucanase (GLU, 15U) were significantly higher in control plants inoculated with pathogen after 24h and remained constant at all time points. A similar trend in gene induction for PAL was evident in PGPFs-treated tomato seedlings with or without pathogen inoculation, whereas POX and GLU were upregulated in control plus pathogen-inoculated tomato seedlings. These results determine that the susceptible tomato cultivar is triggered after perception of potent PGPFs to synthesize PAL, POX, and GLU, which activate defence resistance against bacterial wilt disease, thereby contributing to plant health improvement.

  11. Housefly Larva Vermicomposting Efficiently Attenuates Antibiotic Resistance Genes in Swine Manure, with Concomitant Bacterial Population Changes

    PubMed Central

    Wang, Hang; Li, Hongyi; Gilbert, Jack A.; Li, Haibo; Wu, Longhua; Liu, Meng; Wang, Liling; Zhou, Qiansheng; Yuan, Junxiang

    2015-01-01

    Manure from swine treated with antimicrobials as feed additives is a major source for the expansion of the antibiotic resistance gene (ARG) reservoir in the environment. Vermicomposting via housefly larvae (Musca domestica) can be efficiently used to treat manure and regenerate biofertilizer, but few studies have investigated its effect on ARG attenuation. Here, we tracked the abundances of 9 ARGs and the composition and structure of the bacterial communities in manure samples across 6 days of full-scale manure vermicomposting. On day 6, the abundances of genes encoding tetracycline resistance [tet(M), tet(O), tet(Q), and tet(W)] were reduced (P < 0.05), while those of genes encoding sulfonamide resistance (sul1 and sul2) were increased (P < 0.05) when normalized to 16S rRNA. The abundances of tetracycline resistance genes were correlated (P < 0.05) with the changing concentrations of tetracyclines in the manure. The overall diversity and richness of the bacteria significantly decreased during vermicomposting, accompanied by a 100 times increase in the relative abundance of Flavobacteriaceae spp. Variations in the abundances of ARGs were correlated with the changing microbial community structure and the relative abundances of the family Ruminococcaceae, class Bacilli, or phylum Proteobacteria. Vermicomposting, as a waste management practice, can reduce the overall abundance of ARGs. More research is warranted to assess the use of this waste management practice as a measure to attenuate the dissemination of antimicrobial residues and ARGs from livestock production before vermicompost can be safely used as biofertilizer in agroecosystems. PMID:26296728

  12. Housefly Larva Vermicomposting Efficiently Attenuates Antibiotic Resistance Genes in Swine Manure, with Concomitant Bacterial Population Changes.

    PubMed

    Wang, Hang; Li, Hongyi; Gilbert, Jack A; Li, Haibo; Wu, Longhua; Liu, Meng; Wang, Liling; Zhou, Qiansheng; Yuan, Junxiang; Zhang, Zhijian

    2015-11-01

    Manure from swine treated with antimicrobials as feed additives is a major source for the expansion of the antibiotic resistance gene (ARG) reservoir in the environment. Vermicomposting via housefly larvae (Musca domestica) can be efficiently used to treat manure and regenerate biofertilizer, but few studies have investigated its effect on ARG attenuation. Here, we tracked the abundances of 9 ARGs and the composition and structure of the bacterial communities in manure samples across 6 days of full-scale manure vermicomposting. On day 6, the abundances of genes encoding tetracycline resistance [tet(M), tet(O), tet(Q), and tet(W)] were reduced (P < 0.05), while those of genes encoding sulfonamide resistance (sul1 and sul2) were increased (P < 0.05) when normalized to 16S rRNA. The abundances of tetracycline resistance genes were correlated (P < 0.05) with the changing concentrations of tetracyclines in the manure. The overall diversity and richness of the bacteria significantly decreased during vermicomposting, accompanied by a 100 times increase in the relative abundance of Flavobacteriaceae spp. Variations in the abundances of ARGs were correlated with the changing microbial community structure and the relative abundances of the family Ruminococcaceae, class Bacilli, or phylum Proteobacteria. Vermicomposting, as a waste management practice, can reduce the overall abundance of ARGs. More research is warranted to assess the use of this waste management practice as a measure to attenuate the dissemination of antimicrobial residues and ARGs from livestock production before vermicompost can be safely used as biofertilizer in agroecosystems.

  13. Ectopic activation of the rice NLR heteropair RGA4/RGA5 confers resistance to bacterial blight and bacterial leaf streak diseases.

    PubMed

    Hutin, Mathilde; Césari, Stella; Chalvon, Véronique; Michel, Corinne; Tran, Tuan Tu; Boch, Jens; Koebnik, Ralf; Szurek, Boris; Kroj, Thomas

    2016-10-01

    Bacterial blight (BB) and bacterial leaf streak (BLS) are important diseases in Oryza sativa caused by Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), respectively. In both bacteria, transcription activator-like (TAL) effectors are major virulence determinants that act by transactivating host genes downstream of effector-binding elements (EBEs) bound in a sequence-specific manner. Resistance to Xoo is mostly related to the action of TAL effectors, either by polymorphisms that prevent the induction of susceptibility (S) genes or by executor (R) genes with EBEs embedded in their promoter, and that induce cell death and resistance. For Xoc, no resistance sources are known in rice. Here, we investigated whether the recognition of effectors by nucleotide binding and leucine-rich repeat domain immune receptors (NLRs), the most widespread resistance mechanism in plants, is also able to stop BB and BLS. In one instance, transgenic rice lines harboring the AVR1-CO39 effector gene from the rice blast fungus Magnaporthe oryzae, under the control of an inducible promoter, were challenged with transgenic Xoo and Xoc strains carrying a TAL effector designed to transactivate the inducible promoter. This induced AVR1-CO39 expression and triggered BB and BLS resistance when the corresponding Pi-CO39 resistance locus was present. In a second example, the transactivation of an auto-active NLR by Xoo-delivered designer TAL effectors resulted in BB resistance, demonstrating that NLR-triggered immune responses efficiently control Xoo. This forms the foundation for future BB and BLS disease control strategies, whereupon endogenous TAL effectors will target synthetic promoter regions of Avr or NLR executor genes.

  14. The evolution of bacterial resistance against bacteriophages in the horse chestnut phyllosphere is general across both space and time.

    PubMed

    Koskella, Britt; Parr, Nicole

    2015-08-19

    Insight to the spatial and temporal scales of coevolution is key to predicting the outcome of host-parasite interactions and spread of disease. For bacteria infecting long-lived hosts, selection to overcome host defences is just one factor shaping the course of evolution; populations will also be competing with other microbial species and will themselves be facing infection by bacteriophage viruses. Here, we examine the temporal and spatial patterns of bacterial adaptation against natural phage populations from within leaves of horse chestnut trees. Using a time-shift experiment with both sympatric and allopatric phages from either contemporary or earlier points in the season, we demonstrate that bacterial resistance is higher against phages from the past, regardless of spatial sympatry or how much earlier in the season phages were collected. Similarly, we show that future bacterial hosts are more resistant to both sympatric and allopatric phages than contemporary bacterial hosts. Together, our results suggest the evolution of relatively general bacterial resistance against phages in nature and are contrasting to previously observed patterns of phage adaptation to bacteria from the same tree hosts over the same time frame, indicating a potential asymmetry in coevolutionary dynamics.

  15. The evolution of bacterial resistance against bacteriophages in the horse chestnut phyllosphere is general across both space and time

    PubMed Central

    Koskella, Britt; Parr, Nicole

    2015-01-01

    Insight to the spatial and temporal scales of coevolution is key to predicting the outcome of host–parasite interactions and spread of disease. For bacteria infecting long-lived hosts, selection to overcome host defences is just one factor shaping the course of evolution; populations will also be competing with other microbial species and will themselves be facing infection by bacteriophage viruses. Here, we examine the temporal and spatial patterns of bacterial adaptation against natural phage populations from within leaves of horse chestnut trees. Using a time-shift experiment with both sympatric and allopatric phages from either contemporary or earlier points in the season, we demonstrate that bacterial resistance is higher against phages from the past, regardless of spatial sympatry or how much earlier in the season phages were collected. Similarly, we show that future bacterial hosts are more resistant to both sympatric and allopatric phages than contemporary bacterial hosts. Together, our results suggest the evolution of relatively general bacterial resistance against phages in nature and are contrasting to previously observed patterns of phage adaptation to bacteria from the same tree hosts over the same time frame, indicating a potential asymmetry in coevolutionary dynamics. PMID:26150663

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

    PubMed

    Aydin, Sevcan; Ince, Bahar; Ince, Orhan

    2016-05-01

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

  17. The Terminal Oxidase Cytochrome bd Promotes Sulfide-resistant Bacterial Respiration and Growth

    PubMed Central

    Forte, Elena; Borisov, Vitaliy B.; Falabella, Micol; Colaço, Henrique G.; Tinajero-Trejo, Mariana; Poole, Robert K.; Vicente, João B.; Sarti, Paolo; Giuffrè, Alessandro

    2016-01-01

    Hydrogen sulfide (H2S) impairs mitochondrial respiration by potently inhibiting the heme-copper cytochrome c oxidase. Since many prokaryotes, including Escherichia (E.) coli, generate H2S and encounter high H2S levels particularly in the human gut, herein we tested whether bacteria can sustain sulfide-resistant O2-dependent respiration. E. coli has three respiratory oxidases, the cyanide-sensitive heme-copper bo3 enzyme and two bd oxidases much less sensitive to cyanide. Working on the isolated enzymes, we found that, whereas the bo3 oxidase is inhibited by sulfide with half-maximal inhibitory concentration IC50 = 1.1 ± 0.1 μM, under identical experimental conditions both bd oxidases are insensitive to sulfide up to 58 μM. In E. coli respiratory mutants, both O2-consumption and aerobic growth proved to be severely impaired by sulfide when respiration was sustained by the bo3 oxidase alone, but unaffected by ≤200 μM sulfide when either bd enzyme acted as the only terminal oxidase. Accordingly, wild-type E. coli showed sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases. In all tested conditions, cyanide mimicked the functional effect of sulfide on bacterial respiration. We conclude that bd oxidases promote sulfide-resistant O2-consumption and growth in E. coli and possibly other bacteria. The impact of this discovery is discussed. PMID:27030302

  18. Caenorhabditis elegans Bacterial Pathogen Resistant bus-4 Mutants Produce Altered Mucins

    PubMed Central

    Parsons, Lisa M.; Mizanur, Rahman M.; Jankowska, Ewa; Hodgkin, Jonathan; O′Rourke, Delia; Stroud, Dave; Ghosh, Salil; Cipollo, John F.

    2014-01-01

    Caenorabditis elegans bus-4 glycosyltransferase mutants are resistant to infection by Microbacterium nematophilum, Yersinia pestis and Yersinia pseudotuberculosis and have altered susceptibility to two Leucobacter species Verde1 and Verde2. Our objective in this study was to define the glycosylation changes leading to this phenotype to better understand how these changes lead to pathogen resistance. We performed MALDI-TOF MS, tandem MS and GC/MS experiments to reveal fine structural detail for the bus-4 N- and O-glycan pools. We observed dramatic changes in O-glycans and moderate ones in N-glycan pools compared to the parent strain. Ce core-I glycans, the nematode's mucin glycan equivalent, were doubled in abundance, halved in charge and bore shifts in terminal substitutions. The fucosyl O-glycans, Ce core-II and neutral fucosyl forms, were also increased in abundance as were fucosyl N-glycans. Quantitative expression analysis revealed that two mucins, let-653 and osm-8, were upregulated nearly 40 fold and also revealed was a dramatic increase in GDP-Man 4,6 dehydratease expression. We performed detailed lectin binding studies that showed changes in glycoconjugates in the surface coat, cuticle surface and intestine. The combined changes in cell surface glycoconjugate distribution, increased abundance and altered properties of mucin provide an environment where likely the above pathogens are not exposed to normal glycoconjugate dependent cues leading to barriers to these bacterial infections. PMID:25296196

  19. The Terminal Oxidase Cytochrome bd Promotes Sulfide-resistant Bacterial Respiration and Growth.

    PubMed

    Forte, Elena; Borisov, Vitaliy B; Falabella, Micol; Colaço, Henrique G; Tinajero-Trejo, Mariana; Poole, Robert K; Vicente, João B; Sarti, Paolo; Giuffrè, Alessandro

    2016-03-31

    Hydrogen sulfide (H2S) impairs mitochondrial respiration by potently inhibiting the heme-copper cytochrome c oxidase. Since many prokaryotes, including Escherichia (E.) coli, generate H2S and encounter high H2S levels particularly in the human gut, herein we tested whether bacteria can sustain sulfide-resistant O2-dependent respiration. E. coli has three respiratory oxidases, the cyanide-sensitive heme-copper bo3 enzyme and two bd oxidases much less sensitive to cyanide. Working on the isolated enzymes, we found that, whereas the bo3 oxidase is inhibited by sulfide with half-maximal inhibitory concentration IC50 = 1.1 ± 0.1 μM, under identical experimental conditions both bd oxidases are insensitive to sulfide up to 58 μM. In E. coli respiratory mutants, both O2-consumption and aerobic growth proved to be severely impaired by sulfide when respiration was sustained by the bo3 oxidase alone, but unaffected by ≤200 μM sulfide when either bd enzyme acted as the only terminal oxidase. Accordingly, wild-type E. coli showed sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases. In all tested conditions, cyanide mimicked the functional effect of sulfide on bacterial respiration. We conclude that bd oxidases promote sulfide-resistant O2-consumption and growth in E. coli and possibly other bacteria. The impact of this discovery is discussed.

  20. Nucleotide diversity analysis of three major bacterial blight resistance genes in rice.

    PubMed

    Bimolata, Waikhom; Kumar, Anirudh; M, Sai Kiran Reddy; Sundaram, Raman Meenakshi; Laha, Gouri Sankar; Qureshi, Insaf Ahmed; Ghazi, Irfan Ahmad

    2015-01-01

    Nucleotide sequence polymorphisms among R gene alleles influence the process of co-evolutionary interaction between host and pathogen by shaping the response of host plants towards invading pathogens. Here, we present the DNA sequence polymorphisms and diversities present among natural alleles of three rice bacterial blight resistance genes, Xa21, Xa26 and xa5. The diversity was examined across different wild relatives and cultivars of Oryza species. Functional significance of selected alleles was evaluated through semi-quantitative reverse transcription polymerase chain reaction and real time PCR. The greatest nucleotide diversity and singleton variable sites (SVS) were present in Xa26 (π = 0.01958; SVS = 182) followed by xa5 and Xa21 alleles. The highest frequency of single nucleotide polymorphisms were observed in Xa21 alleles and least in xa5. Transition bias was observed in all the genes and 'G' to 'A' transitions were more favored than other form of transitions. Neutrality tests failed to show the presence of selection at these loci, though negative Tajima's D values indicate the presence of a rare form of polymorphisms. At the interspecies level, O. nivara exhibited more diversity than O. sativa. We have also identified two nearly identical resistant alleles of xa5 and two sequentially identical alleles of Xa21. The alleles of xa5 showed basal levels of expression while Xa21 alleles were functionally not expressed.

  1. Sequence-Specific Targeting of Bacterial Resistance Genes Increases Antibiotic Efficacy

    PubMed Central

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

    2016-01-01

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

  2. Bioremediation potential of a highly mercury resistant bacterial strain Sphingobium SA2 isolated from contaminated soil.

    PubMed

    Mahbub, Khandaker Rayhan; Krishnan, Kannan; Megharaj, Mallavarapu; Naidu, Ravi

    2016-02-01

    A mercury resistant bacterial strain, SA2, was isolated from soil contaminated with mercury. The 16S rRNA gene sequence of this isolate showed 99% sequence similarity to the genera Sphingobium and Sphingomonas of α-proteobacteria group. However, the isolate formed a distinct phyletic line with the genus Sphingobium suggesting the strain belongs to Sphingobium sp. Toxicity studies indicated resistance to high levels of mercury with estimated EC50 values 4.5 mg L(-1) and 44.15 mg L(-1) and MIC values 5.1 mg L(-1) and 48.48 mg L(-1) in minimal and rich media, respectively. The strain SA2 was able to volatilize mercury by producing mercuric reductase enzyme which makes it potential candidate for remediating mercury. ICP-QQQ-MS analysis of Hg supplemented culture solutions confirmed that almost 79% mercury in the culture suspension was volatilized in 6 h. A very small amount of mercury was observed to accumulate in cell pellets which was also evident according to ESEM-EDX analysis. The mercuric reductase gene merA was amplified and sequenced. The deduced amino acid sequence demonstrated sequence homology with α-proteobacteria and Ascomycota group.

  3. Resistance and resilience responses of a range of soil eukaryote and bacterial taxa to fungicide application

    PubMed Central

    Howell, Christopher C.; Hilton, Sally; Semple, Kirk T.; Bending, Gary D.

    2014-01-01

    The application of plant protection products has the potential to significantly affect soil microbial community structure and function. However, the extent to which soil microbial communities from different trophic levels exhibit resistance and resilience to such compounds remains poorly understood. The resistance and resilience responses of a range of microbial communities (bacteria, fungi, archaea, pseudomonads, and nematodes) to different concentrations of the strobilurin fungicide, azoxystrobin were studied. A significant concentration-dependent decrease, and subsequent recovery in soil dehydrogenase activity was recorded, but no significant impact on total microbial biomass was observed. Impacts on specific microbial communities were studied using small subunit (SSU) rRNA terminal restriction fragment length polymorphism (T-RFLP) profiling using soil DNA and RNA. The application of azoxystrobin significantly affected fungal and nematode community structure and diversity but had no impact on other communities. Community impacts were more pronounced in the RNA-derived T-RFLP profiles than in the DNA-derived profiles. qPCR confirmed that azoxystrobin application significantly reduced fungal, but not bacterial, SSU rRNA gene copy number. Azoxystrobin application reduced the prevalence of ascomycete fungi, but increased the relative abundance of zygomycetes. Azoxystrobin amendment also reduced the relative abundance of nematodes in the order Enoplia, but stimulated a large increase in the relative abundance of nematodes from the order Araeolaimida. PMID:25048906

  4. Identification of single nucleotide polymorphism markers associated with bacterial cold water disease resistance and spleen size in rainbow trout

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial cold water disease (BCWD) is one of the frequent causes of elevated mortality in salmonid aquaculture. Previously, we identified and validated microsatellite markers associated with QTL (quantitative trait loci) for BCWD resistance and spleen size in rainbow trout. The objective of this st...

  5. Evaluation of triticale accessions for resistance to wheat bacterial leaf streak caused by Xanthomonas translucens pv. undulosa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The bacterium Xanthomonas translucens pv. undulosa (Xtu) causes bacterial leaf streak (BLS) on wheat and other small grains. Several triticale accessions were reported to possess high levels of resistance to wheat Xtu strains. In this study, we evaluated a worldwide collection of 502 triticale acces...

  6. Association mapping of quantitative trait loci responsible for resistance to Bacterial Leaf Streak and Spot Blotch in spring wheat landraces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa, and spot blotch (SB), caused by Cochliobolus sativus are two major diseases of wheat (Triticum aestivum L.). Planting resistant cultivars is the best approach to manage these diseases and identifying new sources of resistan...

  7. The inheritance of resistance to bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians in three lettuce cultivars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lettuce yields can be reduced by the disease bacterial leaf spot (BLS) caused by the pathogen Xanthomonas campestris pv. vitians (Xcv) and host resistance is the most feasible method to reduce disease losses. The cultivars La Brillante, Pavane, and Little Gem express an incompatible host-pathogen in...

  8. Identification of single nucleotide polymorphism markers associated with bacterial cold water disease resistance and spleen size in rainbow trout

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial cold water disease (BCWD) is one of the frequent causes of elevated mortality in salmonid aquaculture. Previously, we identified and validated microsatellites associated with QTL (quantitative trait loci) for BCWD resistance and spleen size in rainbow trout. The objective of this study was...

  9. Genetic Diversity of Lettuce (Lactuca sativa) for Resistance to Bacterial Leaf Spot Caused by Xanthomonas campestris pv. vitians.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lettuce plants were artificially inoculated with three isolates of Xanthomonas campestris pv. vitians in field and greenhouse evaluations for genetic variation in resistance to bacterial leaf spot. The cultivar Little Gem had the least amount of disease, whether evaluated for disease severity or dis...

  10. Genome-wide association studies identify 25 genetic loci associated with resistance to Bacterial Cold Water Disease in rainbow trout

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial cold water disease (BCWD) causes significant mortality and economic losses in salmonids aquaculture. In previous studies we have identified moderate-large effect QTL for BCWD resistance in rainbow trout (Oncorhynchus mykiss). However, the recent availability of a high density SNP array and...

  11. Altering the thermal resistance of foodborne bacterial pathogens with an eggshell membrane waste by-product.

    PubMed

    Poland, A L; Sheldon, B W

    2001-04-01

    Eggshells from egg-breaking operations are a significant waste disposal problem. Thus, the development of value-added by-products from this waste would be welcomed by the industry. The ability of extracted eggshell membranes containing, several bacteriolytic enzymes (i.e., lysozyme and beta-N-acetylglucosaminidase) or other membrane components to alter the thermal resistance of gram-positive and gram-negative bacterial pathogens was evaluated. Mid-log phase cells of Salmonella Enteritidis (SE), Salmonella Typhimurium (ST), Escherichia coli O157:H7 (EC), Listeria monocytogenes Scott A (LM), and Staphylococcus aureus (SA) were suspended in 100 ml of 0.1% peptone water (pH 6.9, 10(7-8) CFU/ml) containing either 0 (control) or 10 g of an eggshell membrane extract and incubated at 37 degrees C for 45 min. Following exposure, membrane-free samples (1.5 ml) were heated in a 56 degrees C (LM, SA), 54 degrees C (SE, ST), or 52 degrees C (EC) water bath from 0 to 14 min in sealed glass reaction vials (12 by 32 mm), and the survivors were recovered on brain heart infusion agar. Population reductions ranging from 27.6% (SA) to 99.8% (LM) (ST, 43.8%; SE, 47.5%; EC, 71.8%) were observed for cells treated for 45 min with extracted membrane, as compared to controls. D-value reductions ranging from 0 (LM) to 87.2% (SE) (SA, 36.7%; EC, 83.3%; ST, 86.3%) were observed when membrane-treated cells were subsequently heat inactivated. The effects of exposure pH, time, temperature, and organic load on membrane activity were also evaluated with Salmonella Typhimurium. Exposure pH (5.0 versus 6.9), time (15 versus 45 min), and temperature (4 degrees C versus 37 degrees C) did not significantly reduce the impact of eggshell membranes on D-values. However, the presence of organic matter (0.1% peptone water versus skim milk) significantly reduced the thermal resistance-reducing capacity of the membranes. These preliminary findings provide information on the potential use of extracted eggshell

  12. A genome-wide association study identifies a horizontally transferred bacterial surface adhesin gene associated with antimicrobial resistant strains

    PubMed Central

    Suzuki, Masato; Shibayama, Keigo; Yahara, Koji

    2016-01-01

    Carbapenems are a class of last-resort antibiotics; thus, the increase in bacterial carbapenem-resistance is a serious public health threat. Acinetobacter baumannii is one of the microorganisms that can acquire carbapenem-resistance; it causes severe nosocomial infection, and is notoriously difficult to control in hospitals. Recently, a machine-learning approach was first used to analyze the genome sequences of hundreds of susceptible and resistant A. baumannii strains, including those carrying commonly acquired resistant mechanisms, to build a classifier that can predict strain resistance. A complementary approach is to explore novel genetic elements that could be associated with the antimicrobial resistance of strains, independent of known mechanisms. Therefore, we carefully selected A. baumannii strains, spanning various genotypes, from public genome databases, and conducted the first genome-wide association study (GWAS) of carbapenem resistance. We employed a recently developed method, capable of identifying any kind of genetic variation and accounting for bacterial population structure, and evaluated its effectiveness. Our study identified a surface adhesin gene that had been horizontally transferred to an ancestral branch of A. baumannii, as well as a specific region of that gene that appeared to accumulate multiple individual variations across the different branches of carbapenem-resistant A. baumannii strains. PMID:27892531

  13. Assessment of Relationship Between Bacterial Stripe Resistance And Leaf Protein Bands In Rice (Oryza sativa L.) Varieties.

    NASA Astrophysics Data System (ADS)

    Talei, D.; Fotokian, M. H.

    2008-01-01

    Bacterial stripe as a new rice disease in Iran is more frequent nowadays. The objective of this study was to assessment of resistance in rice varieties together with evaluating of zymogram bands resulted from SDS PAGE electrophoresis of leaf proteins. For this purpose, 30 lines were tested in a randomized complete block design with three replications. The analysis of variance showed that there was significant difference between genotypes for resistance. Mean compare based on field results revealed that Domsiyah had the lowest resistance while Nemat and 7162 demonstrated the highest resistance. Laboratory results showed that there were significant difference between protein bands resulted from sensitive and resistance verities. Twenty bands were observed through SDS PAGE electrophoresis of leaf proteins. The 9th and 12th bands were found in sensitive varieties while were not in resistance genotypes. According to the results of this study, 7162 variety can be considered as the sources of resistance in breeding programs. Meanwhile attending to existence of 9th and 12th bands in sensitive varieties, resistance against bacterial stripe of rice maybe influenced by absence of these proteins.

  14. Interaction of common bacterial blight bacteria with disease resistance quantitative trait loci in common bean.

    PubMed

    Duncan, Robert W; Singh, Shree P; Gilbertson, Robert L

    2011-04-01

    Common bacterial blight (CBB) of common bean (Phaseolus vulgaris L.) is caused by Xanthomonas campestris pv. phaseoli and X. fuscans subsp. fuscans, and is the most important bacterial disease of this crop in many regions of the world. In 2005 and 2006, dark red kidney bean fields in a major bean-growing region in central Wisconsin were surveyed for CBB incidence and representative symptomatic leaves collected. Xanthomonad-like bacteria were isolated from these leaves and characterized based upon phenotypic (colony) characteristics, pathogenicity on common bean, polymerase chain reaction (PCR) with X. campestris pv. phaseoli- and X. fuscans subsp. fuscans-specific primers, and repetitive-element PCR (rep-PCR) and 16S-28S ribosomal RNA spacer region sequence analyses. Of 348 isolates that were characterized, 293 were identified as common blight bacteria (i.e., pathogenic on common bean and positive in PCR tests with the X. campestris pv. phaseoli- and X. fuscans subsp. fuscans-specific primers), whereas the other isolates were nonpathogenic xanthomonads. Most (98%) of the pathogenic xanthomonads were X. campestris pv. phaseoli, consistent with the association of this bacterium with CBB in large-seeded bean cultivars of the Andean gene pool. Two types of X. campestris pv. phaseoli were involved with CBB in this region: typical X. campestris pv. phaseoli (P) isolates with yellow mucoid colonies, no brown pigment production, and a typical X. campestris pv. phaseoli rep-PCR fingerprint (60% of strains); and a new phenotype and genotype (Px) with an X. campestris pv. phaseoli-type fingerprint and less mucoid colonies that produced brown pigment (40% of strains). In addition, a small number of X. fuscans subsp. fuscans strains, representing a new genotype (FH), were isolated from two fields in 2005. Representative P and Px X. campestris pv. phaseoli strains, an FH X. fuscans subsp. fuscans strain, plus five previously characterized X. campestris pv. phaseoli and X

  15. Antibacterial Activity of Salvadora persica L. (Miswak) Extracts against Multidrug Resistant Bacterial Clinical Isolates.

    PubMed

    Al-Ayed, Mohamed Saeed Zayed; Asaad, Ahmed Morad; Qureshi, Mohamed Ansar; Attia, Hany Goda; AlMarrani, Abduljabbar Hadi

    2016-01-01

    Much effort has focused on examining the inhibitory effect of Salvadora persica (miswak) on oral microorganisms, but information concerning its antibacterial activity against other human pathogens, particularly multidrug resistant (MDR) isolates, is scarce. Therefore, this study aimed to assess the in vitro antibacterial activities of Salvadora persica L. extracts against 10 MDR bacterial clinical isolates other than oral pathogens. The antibacterial activity of aqueous and methanol miswak extracts was assessed using the agar dilution and minimum inhibitory concentration (MIC) methods. Overall, the 400 mg/mL of miswak extract was the most effective on all strains. The methanol extract exhibited a stronger antibacterial activity against Gram-negative (3.3-13.6 mm) than Gram-positive (1.8-8.3 mm) bacteria. The lowest MIC value was seen for E. coli (0.39, 1.56 µg/mL), followed by Streptococcus pyogenes (1.56 µg/mL). The highest MIC value (6.25, 12.5 µg/mL) was recorded for methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii, and Stenotrophomonas maltophilia. This study demonstrates, for the first time, the moderate to strong antibacterial activity of miswak extracts against all tested MDR-pathogens. Methanol extract appears to be a potent antimicrobial agent that could be considered as complementary and alternative medicine against resistant pathogens. Further studies on a large number of MDR organisms are necessary to investigate and standardize the inhibitory effect of miswak extracts against these emerging pathogens.

  16. Antibacterial Activity of Salvadora persica L. (Miswak) Extracts against Multidrug Resistant Bacterial Clinical Isolates

    PubMed Central

    Al-Ayed, Mohamed Saeed Zayed; Asaad, Ahmed Morad; Qureshi, Mohamed Ansar; Attia, Hany Goda; AlMarrani, Abduljabbar Hadi

    2016-01-01

    Much effort has focused on examining the inhibitory effect of Salvadora persica (miswak) on oral microorganisms, but information concerning its antibacterial activity against other human pathogens, particularly multidrug resistant (MDR) isolates, is scarce. Therefore, this study aimed to assess the in vitro antibacterial activities of Salvadora persica L. extracts against 10 MDR bacterial clinical isolates other than oral pathogens. The antibacterial activity of aqueous and methanol miswak extracts was assessed using the agar dilution and minimum inhibitory concentration (MIC) methods. Overall, the 400 mg/mL of miswak extract was the most effective on all strains. The methanol extract exhibited a stronger antibacterial activity against Gram-negative (3.3–13.6 mm) than Gram-positive (1.8–8.3 mm) bacteria. The lowest MIC value was seen for E. coli (0.39, 1.56 µg/mL), followed by Streptococcus pyogenes (1.56 µg/mL). The highest MIC value (6.25, 12.5 µg/mL) was recorded for methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii, and Stenotrophomonas maltophilia. This study demonstrates, for the first time, the moderate to strong antibacterial activity of miswak extracts against all tested MDR-pathogens. Methanol extract appears to be a potent antimicrobial agent that could be considered as complementary and alternative medicine against resistant pathogens. Further studies on a large number of MDR organisms are necessary to investigate and standardize the inhibitory effect of miswak extracts against these emerging pathogens. PMID:26904146

  17. Atmospheric pressure resistive barrier air plasma jet induced bacterial inactivation in aqueous environment

    NASA Astrophysics Data System (ADS)

    Thiyagarajan, Magesh; Sarani, Abdollah; Gonzales, Xavier

    2013-03-01

    An atmospheric pressure resistive barrier air plasma jet is designed to inactivate bacteria in aqueous media in direct and indirect exposure modes of treatment. The resistive barrier plasma jet is designed to operate at both dc and standard 50-60 Hz low frequency ac power input and the ambient air at 50% humidity level was used as the operating gas. The voltage-current characteristics of the plasma jet were analyzed and the operating frequency of the discharge was measured to be 20 kHz and the plasma power was measured to be 26 W. The plasma jet rotational temperatures (Trot) are obtained from the optical emission spectra, from the N2C-B(2+) transitions by matching the experimental spectrum results with the Spectra Air (SPECAIR) simulation spectra. The reactive oxygen and nitrogen species were measured using optical emission spectroscopy and gas analyzers, for direct and indirect treatment modes. The nitric oxides (NO) were observed to be the predominant long lived reactive nitrogen species produced by the plasma. Three different bacteria including Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Neisseria meningitidis (Gram-negative) were suspended in an aqueous media and treated by the resistive barrier air plasma jet in direct and indirect exposure modes. The results show that a near complete bacterial inactivation was achieved within 120 s for both direct and indirect plasma treatment of S. aureus and E. coli bacteria. Conversely, a partial inactivation of N. meningitidis was observed by 120 s direct plasma exposure and insignificant inactivation was observed for the indirect plasma exposure treatment. Plasma induced shifts in N. meningitidis gene expression was analyzed using pilC gene expression as a representative gene and the results showed a reduction in the expression of the pilC gene compared to untreated samples suggesting that the observed protection against NO may be regulated by other genes.

  18. Bacterial silver resistance: molecular biology and uses and misuses of silver compounds.

    PubMed

    Silver, Simon

    2003-06-01

    Resistance to silver compounds as determined by bacterial plasmids and genes has been defined by molecular genetics. Silver resistance conferred by the Salmonella plasmid pMGH100 involves nine genes in three transcription units. A sensor/responder (SilRS) two-component transcriptional regulatory system governs synthesis of a periplasmic Ag(I)-binding protein (SilE) and two efflux pumps (a P-type ATPase (SilP) plus a three-protein chemiosmotic RND Ag(I)/H+ exchange system (SilCBA)). The same genes were identified on five of 19 additional IncH incompatibility class plasmids but thus far not on other plasmids. Of 70 random enteric isolates from a local hospital, isolates from catheters and other Ag-exposed sites, and total genomes of enteric bacteria, 10 have recognizable sil genes. The centrally located six genes are found and functional in the chromosome of Escherichia coli K-12, and also occur on the genome of E. coli O157:H7. The use of molecular epidemiological tools will establish the range and diversity of such resistance systems in clinical and non-clinical sources. Silver compounds are used widely as effective antimicrobial agents to combat pathogens (bacteria, viruses and eukaryotic microorganisms) in the clinic and for public health hygiene. Silver cations (Ag+) are microcidal at low concentrations and used to treat burns, wounds and ulcers. Ag is used to coat catheters to retard microbial biofilm development. Ag is used in hygiene products including face creams, "alternative medicine" health supplements, supermarket products for washing vegetables, and water filtration cartridges. Ag is generally without adverse effects for humans, and argyria (irreversible discoloration of the skin resulting from subepithelial silver deposits) is rare and mostly of cosmetic concern.

  19. The resistance of bacterial isolates from spacecraft assembly cleanrooms against physical and chemical treatments

    NASA Astrophysics Data System (ADS)

    Rettberg, Petra; Kloss, Maria; Barczyk, Simon; Reitz, Guenther

    The COSPAR planetary protection guidelines define bioburden limits for spacecraft to protect solar system bodies from contamination by terrestrial life, and to protect Earth from possible life forms that may be returned from other solar system bodies. The cleaning and sterilisation methods to be selected for space hardware have to be as efficient as necessary to reach the maximal allowed bioburden limit. To be able to asses the suitability of different methods it is mandatory to investigate the physiological potential of the microbial isolates from cleanrooms. In the ESA project BioDiv the bioburden and biodiversity was determined in cleanrooms where the satellite Herschel was integrated and tested. From all bacterial isolates obtained in sev-eral measurement campaigns 30 strains were selected. Their resistance as vegetative cells was tested against different physical and chemical treatments: drying under ambient conditions, desiccation under defined relative humidity, vacuum exposure, UVC radiation exposure, freeze-thaw cycles under martian atmosphere and pressure, exposure to high and low pH values, and exposure to alcohols. The results of these tests can be summarised as follows: i) Most of the tested microorganisms from cleanrooms exhibit a certain resistance against one or more of the tested conditions. This is in contrast to strains which have already been cultured for long-periods in time under optimal laboratory conditions. They tend to loose their original resistance against different environmental parameters. ii) Different isolates from the same species can exhibit significantly different resistances. Therefore, the sole identification of microorgnisms by 16S rDNA sequencing does not give insights into their physiological potential. iii) The first hours of drying have a substantial inactiviation effect, longer periods of drying or even vacuum exposure reduce the surviving fraction only slightly more. iv) The sensitivity against UVC radiation varies

  20. [Profile of bacterial resistance in pediatric urinary tract infections in 2014].

    PubMed

    Flammang, A; Morello, R; Vergnaud, M; Brouard, J; Eckart, P

    2017-03-01

    In pediatric units, bacteria-producing extended-spectrum-betalactamase (ESBL) have an increasing prevalence among bacteria causing febrile urinary tract infections (UTIs). The purpose of this study was to evaluate the epidemiology of bacteria resistance patterns observed in UTIs, in order to assess the current antibiotic treatment protocols. This study is based upon a single-center retrospective chart review of the cytobacteriological urine cultures performed in UTIs between 1 January and 31 December 2014, in the medical pediatric unit of the Caen University Hospital. Out of the total of 219 cases of UTI, 26.9% were recurrences of UTI, 18.3% were infections in infants less than 3 months old, 21% of the patients suffered from underlying uropathy, and 16.4% of the patients had recently been exposed to antibiotics. In 80.3% of the cases, Escherichia coli was found, while Enterococcus faecalis was found in 5.6%. The antibiograms proved that 33.5% of the bacteria were sensitive. Half of E. coli were resistant to ampicillin, 4.9% to cefixime, 4.9% to ceftriaxone, 1.1% to gentamicin, and 27.8% to trimethoprim-sulfamethoxazole. Nine E. coli and one Enterobacter cloacae produced ESBL, accounting for 4.6% of the UTIs. We did not find any bacteria-producing high-level cephalosporinase. Cefixime resistance was statistically linked to ongoing antibiotic treatment (OR=5.98; 95% CI [1.44; 24.91], P=0.014) and underlying uropathy (OR=6.24; 95% CI [1.47; 26.42], P=0.013). Ceftriaxone resistance was statistically related to ongoing antibiotic treatment (OR=6.93; 95% CI [1.45; 33.13], P=0.015). These results argue in favor of maintaining intravenous ceftriaxone for probabilistic ambulatory treatment. However, in case of hospitalization, cefotaxime can replace ceftriaxone, due to its lower ecological impact. Moreover, it is necessary to continue monitoring bacterial resistance and regularly review our treatment protocols.

  1. Antibiotic resistance genes in bacterial and bacteriophage fractions of Tunisian and Spanish wastewaters as markers to compare the antibiotic resistance patterns in each population.

    PubMed

    Colomer-Lluch, Marta; Calero-Cáceres, William; Jebri, Sihem; Hmaied, Fatma; Muniesa, Maite; Jofre, Juan

    2014-12-01

    The emergence and increased prevalence of antibiotic resistance genes (ARGs) in the environment may pose a serious global health concern. This study evaluates the abundance of several ARGs in bacterial and bacteriophage DNA via real-time qPCR in samples from five different sampling points in Tunisia; three wastewater treatment plants (WWTP 1, 2 and 3) and wastewater from two abattoirs slaughtering different animals. Results are compared with those obtained in the Barcelona area, in northeast Spain. Eight ARGs were quantified by qPCR from total and phage DNA fraction from the samples. Three β-lactamases (bla(TEM), bla(CTX-M) cluster 1 and bla(CTX-M) cluster 9), two quinolone resistance genes (qnrA and qnrS), the mecA gene that confers resistance to methicillin in Staphylococcus aureus, the emerging armA gene, conferring resistance to aminoglycosides and sul1, the most extended gene conferring resistance to sulfonamides, were evaluated. Sul1 and bla(TEM) were the most prevalent ARGs detected at all five Tunisian sampling points, similarly with the observations in Barcelona. bla(CTX-M-9) was more prevalent than bla(CTX-M-1) both in bacterial and DNA within phage particles in all samples analysed. mecA and armA were almost absent in Tunisian waters from human or animal origin in contrast with Barcelona that showed a medium prevalence. qnrA was more prevalent than qnrS in bacterial and phage DNA from all sampling points. In conclusion, our study shows that ARGs are found in the bacterial and is reflected in the phage DNA fraction of human and animal wastewaters. The densities of each ARGs vary depending on the ARGs shed by each population and is determined by the characteristics of each area. Thus, the evaluation of ARGs in wastewaters seems to be suitable as marker reflecting the antibiotic resistance patterns of a population.

  2. Cultivation and qPCR Detection of Pathogenic and Antibiotic-Resistant Bacterial Establishment in Naive Broiler Houses.

    PubMed

    Brooks, J P; McLaughlin, M R; Adeli, A; Miles, D M

    2016-05-01

    Conventional commercial broiler production involves the rearing of more than 20,000 broilers in a single confined space for approximately 6.5 wk. This environment is known for harboring pathogens and antibiotic-resistant bacteria, but studies have focused on previously established houses with mature litter microbial populations. In the current study, a set of three naive houses were followed from inception through 11 broiler flocks and monitored for ambient climatic conditions, bacterial pathogens, and antibiotic resistance. Within the first 3 wk of the first flock cycle, 100% of litter samples were positive for and , whereas was cultivation negative but PCR positive. Antibiotic resistance genes were ubiquitously distributed throughout the litter within the first flock, approaching 10 to 10 genomic units g. Preflock litter levels were approximately 10 CFU g for heterotrophic plate count bacteria, whereas midflock levels were >10 colony forming units (CFU) g; other indicators demonstrated similar increases. The influence of intrahouse sample location was minor. In all likelihood, given that preflock levels were negative for pathogens and antibiotic resistance genes and 4 to 5 Log lower than flock levels for indicators, incoming birds most likely provided the colonizing microbiome, although other sources were not ruled out. Most bacterial groups experienced a cyclical pattern of litter contamination seen in other studies, whereas microbial stabilization required approximately four flocks. This study represents a first-of-its-kind view into the time required for bacterial pathogens and antibiotic resistance to colonize and establish in naive broiler houses.

  3. Overexpression of a C-type lectin enhances bacterial resistance in red swamp crayfish Procambarus clarkii.

    PubMed

    Zhang, Xiao-Wen; Liu, Ying-Ying; Mu, Yi; Ren, Qian; Zhao, Xiao-Fan; Wang, Jin-Xing

    2013-05-01

    C-type lectins play important roles in the innate immune system of crustaceans. In this study, a novel C-type lectin gene, designated as PcLec4, was obtained from the red swamp crayfish (Procambarus clarkii). Quantitative real-time polymerase chain reaction revealed that PcLec4 is mainly expressed in the crayfish hepatopancreas and intestine, and the PcLec4 mRNA expression is upregulated after challenged with the bacteria Vibrio anguillarum. PcLec4 was recombinantly expressed in Escherichia coli and anti-PcLec4 polyclonal antiserum was prepared. Binding experiments revealed that the recombinant PcLec4 binds to various bacteria and polysaccharides on the bacterial surface, which suggests that PcLec4 recognizes bacterial pathogens. Overexpression of PcLec4 in crayfish using the pIeLec4 vector was performed. The results show that the crayfish overexpressing PcLec4 eliminate injected V. anguillarum more quickly than the control, which suggests that PcLec4 elicits further immune response for removing invading bacteria. The results of the survival experiment confirmed the function of PcLec4 in resisting V. anguillarum because PcLec4 overexpression in crayfish significantly increased the crayfish survival rate. These results reveal that PcLec4 has an important role in the antibacterial immunity of crayfish, and in vivo PcLec4 overexpression might be used as a disease control strategy in aquiculture.

  4. Resistance to ketolide antibiotics by coordinated expression of rRNA methyltransferases in a bacterial producer of natural ketolides

    PubMed Central

    Almutairi, Mashal M.; Park, Sung Ryeol; Rose, Simon; Hansen, Douglas A.; Vázquez-Laslop, Nora; Douthwaite, Stephen; Sherman, David H.; Mankin, Alexander S.

    2015-01-01

    Ketolides are promising new antimicrobials effective against a broad range of Gram-positive pathogens, in part because of the low propensity of these drugs to trigger the expression of resistance genes. A natural ketolide pikromycin and a related compound methymycin are produced by Streptomyces venezuelae strain ATCC 15439. The producer avoids the inhibitory effects of its own antibiotics by expressing two paralogous rRNA methylase genes pikR1 and pikR2 with seemingly redundant functions. We show here that the PikR1 and PikR2 enzymes mono- and dimethylate, respectively, the N6 amino group in 23S rRNA nucleotide A2058. PikR1 monomethylase is constitutively expressed; it confers low resistance at low fitness cost and is required for ketolide-induced activation of pikR2 to attain high-level resistance. The regulatory mechanism controlling pikR2 expression has been evolutionary optimized for preferential activation by ketolide antibiotics. The resistance genes and the induction mechanism remain fully functional when transferred to heterologous bacterial hosts. The anticipated wide use of ketolide antibiotics could promote horizontal transfer of these highly efficient resistance genes to pathogens. Taken together, these findings emphasized the need for surveillance of pikR1/pikR2-based bacterial resistance and the preemptive development of drugs that can remain effective against the ketolide-specific resistance mechanism. PMID:26438831

  5. Resistance to ketolide antibiotics by coordinated expression of rRNA methyltransferases in a bacterial producer of natural ketolides.

    PubMed

    Almutairi, Mashal M; Park, Sung Ryeol; Rose, Simon; Hansen, Douglas A; Vázquez-Laslop, Nora; Douthwaite, Stephen; Sherman, David H; Mankin, Alexander S

    2015-10-20

    Ketolides are promising new antimicrobials effective against a broad range of Gram-positive pathogens, in part because of the low propensity of these drugs to trigger the expression of resistance genes. A natural ketolide pikromycin and a related compound methymycin are produced by Streptomyces venezuelae strain ATCC 15439. The producer avoids the inhibitory effects of its own antibiotics by expressing two paralogous rRNA methylase genes pikR1 and pikR2 with seemingly redundant functions. We show here that the PikR1 and PikR2 enzymes mono- and dimethylate, respectively, the N6 amino group in 23S rRNA nucleotide A2058. PikR1 monomethylase is constitutively expressed; it confers low resistance at low fitness cost and is required for ketolide-induced activation of pikR2 to attain high-level resistance. The regulatory mechanism controlling pikR2 expression has been evolutionary optimized for preferential activation by ketolide antibiotics. The resistance genes and the induction mechanism remain fully functional when transferred to heterologous bacterial hosts. The anticipated wide use of ketolide antibiotics could promote horizontal transfer of these highly efficient resistance genes to pathogens. Taken together, these findings emphasized the need for surveillance of pikR1/pikR2-based bacterial resistance and the preemptive development of drugs that can remain effective against the ketolide-specific resistance mechanism.

  6. Drug resistance of bacterial dental biofilm and the potential use of natural compounds as alternative for prevention and treatment.

    PubMed

    Kouidhi, Bochra; Al Qurashi, Yasir Mohammed A; Chaieb, Kamel

    2015-03-01

    Oral diseases, such as dental caries and periodontal disease are directly linked with the ability of bacteria to form biofilm. The development of dental caries involves acidogenic and aciduric Gram-positive bacteria colonizing the supragingival biofilm (Streptococcus, Lactobacillus and Actinomycetes). Periodontal diseases have been linked to anaerobic Gram-negative bacteria forming a subgingival plaque (Porphyromonas gingivalis, Actinobacillus, Prevotella and Fusobacterium). Cells embedded in biofilm are up to 1000-fold more resistant to antibiotics compared to their planctonic ones. Several mechanisms have been proposed to explain biofilms drug resistance. Given the increased bacterial resistance to antibiotics currently used in dentistry, a great importance is given to natural compounds for the prevention of oral bacterial growth, adhesion and colonization. Over the past decade, interest in drugs derived from medicinal plants has markedly increased. It has been well documented that medicinal plants and natural compounds confer considerable antibacterial activity against various microorganisms including cariogenic and periodontal pathogens. This paper provides a review of the literature focusing on the studies on (i) biofilm in the oral cavity, (ii) drug resistance of bacterial biofilm and (iii) the potential use of plant extracts, essential oils and natural compounds as biofilm preventive agents in dentistry, involving their origin and their mechanism of biofilm inhibition.

  7. Overexpression of the Eggplant (Solanum melongena) NAC Family Transcription Factor SmNAC Suppresses Resistance to Bacterial Wilt

    PubMed Central

    Na, Chen; Shuanghua, Wu; Jinglong, Fu; Bihao, Cao; Jianjun, Lei; Changming, Chen; Jin, Jiang

    2016-01-01

    Bacterial wilt (BW) is a serious disease that affects eggplant (Solanum melongena) production. Although resistance to this disease has been reported, the underlying mechanism is unknown. In this study, we identified a NAC family transcription factor (SmNAC) from eggplant and characterized its expression, its localization at the tissue and subcellular levels, and its role in BW resistance. To this end, transgenic eggplant lines were generated in which the expression of SmNAC was constitutively up regulated or suppressed using RNAi. The results indicated that overexpression of SmNAC decreases resistance to BW. Moreover, SmNAC overexpression resulted in the reduced accumulation of the plant immune signaling molecule salicylic acid (SA) and reduced expression of ICS1 (a gene that encode isochorismate synthase 1, which is involved in SA biosynthesis). We propose that reduced SA content results in increased bacterial wilt susceptibility in the transgenic lines. Our results provide important new insights into the regulatory mechanisms of bacterial wilt resistance in eggplant. PMID:27528282

  8. Overexpression of the Eggplant (Solanum melongena) NAC Family Transcription Factor SmNAC Suppresses Resistance to Bacterial Wilt.

    PubMed

    Na, Chen; Shuanghua, Wu; Jinglong, Fu; Bihao, Cao; Jianjun, Lei; Changming, Chen; Jin, Jiang

    2016-08-16

    Bacterial wilt (BW) is a serious disease that affects eggplant (Solanum melongena) production. Although resistance to this disease has been reported, the underlying mechanism is unknown. In this study, we identified a NAC family transcription factor (SmNAC) from eggplant and characterized its expression, its localization at the tissue and subcellular levels, and its role in BW resistance. To this end, transgenic eggplant lines were generated in which the expression of SmNAC was constitutively up regulated or suppressed using RNAi. The results indicated that overexpression of SmNAC decreases resistance to BW. Moreover, SmNAC overexpression resulted in the reduced accumulation of the plant immune signaling molecule salicylic acid (SA) and reduced expression of ICS1 (a gene that encode isochorismate synthase 1, which is involved in SA biosynthesis). We propose that reduced SA content results in increased bacterial wilt susceptibility in the transgenic lines. Our results provide important new insights into the regulatory mechanisms of bacterial wilt resistance in eggplant.

  9. Endotoxin, capsule, and bacterial attachment contribute to Neisseria meningitidis resistance to the human antimicrobial peptide LL-37.

    PubMed

    Jones, Allison; Geörg, Miriam; Maudsdotter, Lisa; Jonsson, Ann-Beth

    2009-06-01

    Pathogenic bacteria have evolved numerous mechanisms to evade the human immune system and have developed widespread resistance to traditional antibiotics. We studied the human pathogen Neisseria meningitidis and present evidence of novel mechanisms of resistance to the human antimicrobial peptide LL-37. We found that bacteria attached to host epithelial cells are resistant to 10 microM LL-37 whereas bacteria in solution or attached to plastic are killed, indicating that the cell microenvironment protects bacteria. The bacterial endotoxin lipooligosaccharide and the polysaccharide capsule contribute to LL-37 resistance, probably by preventing LL-37 from reaching the bacterial membrane, as more LL-37 reaches the bacterial membrane on both lipooligosaccharide-deficient and capsule-deficient mutants whereas both mutants are also more susceptible to LL-37 killing than the wild-type strain. N. meningitidis bacteria respond to sublethal doses of LL-37 and upregulate two of their capsule genes, siaC and siaD, which further results in upregulation of capsule biosynthesis.

  10. Hierarchical nested trial design (HNTD) for demonstrating treatment efficacy of new antibacterial drugs in patient populations with emerging bacterial resistance.

    PubMed

    Huque, Mohammad F; Valappil, Thamban; Soon, Guoxing Greg

    2014-11-10

    In the last decade or so, pharmaceutical drug development activities in the area of new antibacterial drugs for treating serious bacterial diseases have declined, and at the same time, there are worries that the increased prevalence of antibiotic-resistant bacterial infections, especially the increase in drug-resistant Gram-negative infections, limits available treatment options . A recent CDC report, 'Antibiotic Resistance Threats in the United States', indicates that antimicrobial resistance is one of our most serious health threats. However, recently, new ideas have been proposed to change this situation. An idea proposed in this regard is to conduct randomized clinical trials in which some patients, on the basis of a diagnostic test, may show presence of bacterial pathogens that are resistant to the control treatment, whereas remaining patients would show pathogens that are susceptible to the control. The control treatment in such trials can be the standard of care or the best available therapy approved for the disease. Patients in the control arm with resistant pathogens can have the option for rescue therapies if their clinical signs and symptoms worsen. A statistical proposal for such patient populations is to use a hierarchical noninferiority-superiority nested trial design that is informative and allows for treatment-to-control comparisons for the two subpopulations without any statistical penalty. This design can achieve in the same trial dual objectives: (i) to show that the new drug is effective for patients with susceptible pathogens on the basis of a noninferiority test and (ii) to show that it is superior to the control in patients with resistant pathogens. This paper addresses statistical considerations and methods for achieving these two objectives for this design. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  11. Characterization of a disease susceptibility locus for exploring an efficient way to improve rice resistance against bacterial blight.

    PubMed

    Cheng, Qi; Mao, Weihua; Xie, Wenya; Liu, Qinsong; Cao, Jianbo; Yuan, Meng; Zhang, Qinglu; Li, Xianghua; Wang, Shiping

    2017-03-01

    Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is the most harmful bacterial disease of rice worldwide. Previously, we characterized major disease resistance (MR) gene xa25, which confers race-specific resistance to Xoo strain PXO339. The xa25 is a recessive allele of the SWEET13 locus, but SWEET13's interaction with PXO339 and how efficiently using this locus for rice breeding still need to be defined. Here we show that the SWEET13 allele from rice Zhenshan 97 is a susceptibility gene to PXO339. Using this allele's promoter to regulate xa25 resulted in disease, suggesting that the promoter is a key determinant in SWEET13 caused disease in Zhanshan 97 after PXO339 infection. PXO339 transcriptionally induces SWEET13 to cause disease. Partial suppressing SWEET13 expression leads to a high level of resistance to PXO339. Thus, the transcriptionally suppressed SWEET13 functions as xa25 in resistance to PXO339. Hybrid rice is widely grown in many countries. However, recessive MR genes have not been efficiently used for disease resistance breeding in hybrid rice production for both parents of the hybrid have to carry the same recessive gene. However, the suppressed SWEET13 functions dominantly, which will have advantage to improve the resistance of hybrid rice to xa25-incomptible Xoo.

  12. Thermal resistance of naturally occurring airborne bacterial spores. [Viking spacecraft dry heat decontamination simulation

    NASA Technical Reports Server (NTRS)

    Puleo, J. R.; Bergstrom, S. L.; Peeler, J. T.; Oxborrow, G. S.

    1978-01-01

    Simulation of a heat process used in the terminal dry-heat decontamination of the Viking spacecraft is reported. Naturally occurring airborne bacterial spores were collected on Teflon ribbons in selected spacecraft assembly areas and subsequently subjected to dry heat. Thermal inactivation experiments were conducted at 105, 111.7, 120, 125, 130, and 135 C with a moisture level of 1.2 mg of water per liter. Heat survivors were recovered at temperatures of 135 C when a 30-h heating cycle was employed. Survivors were recovered from all cycles studied and randomly selected for identification. The naturally occurring spore population was reduced an average of 2.2 to 4.4 log cycles from 105 to 135 C. Heating cycles of 5 and 15 h at temperature were compared with the standard 30-h cycle at 111.7, 120, and 125 C. No significant differences in inactivation (alpha = 0.05) were observed between 111.7 and 120 C. The 30-h cycle differs from the 5- and 15-h cycles at 125 C. Thus, the heating cycle can be reduced if a small fraction (about 0.001 to 0.0001) of very resistant spores can be tolerated.

  13. The surface layer of Tannerella forsythia contributes to serum resistance and oral bacterial coaggregation.

    PubMed

    Shimotahira, Naohiro; Oogai, Yuichi; Kawada-Matsuo, Miki; Yamada, Sakuo; Fukutsuji, Kenji; Nagano, Keiji; Yoshimura, Fuminobu; Noguchi, Kazuyuki; Komatsuzawa, Hitoshi

    2013-04-01

    Tannerella forsythia is an anaerobic, Gram-negative bacterium involved in the so-called "red complex," which is associated with severe and chronic periodontitis. The surface layer (S-layer) of T. forsythia is composed of cell surface glycoproteins, such as TfsA and TfsB, and is known to play a role in adhesion/invasion and suppression of proinflammatory cytokine expression. Here we investigated the association of this S-layer with serum resistance and coaggregation with other oral bacteria. The growth of the S-layer-deficient mutant in a bacterial medium containing more than 20% non-heat-inactivated calf serum (CS) or more than 40% non-heat-inactivated human serum was significantly suppressed relative to that of the wild type (WT). Next, we used confocal microscopy to perform quantitative analysis on the effect of serum. The survival ratio of the mutant exposed to 100% non-heat-inactivated CS (76% survival) was significantly lower than that of the WT (97% survival). Furthermore, significant C3b deposition was observed in the mutant but not in the WT. In a coaggregation assay, the mutant showed reduced coaggregation with Streptococcus sanguinis, Streptococcus salivarius, and Porphyromonas gingivalis but strong coaggregation with Fusobacterium nucleatum. These results indicated that the S-layer of T. forsythia plays multiple roles in virulence and may be associated with periodontitis.

  14. Method for collecting naturally occurring airborne bacterial spores for determining their thermal resistance.

    PubMed

    Puleo, J R; Favero, M S; Oxborrow, G S; Herring, C M

    1975-11-01

    The ability to determine the thermal resistance of naturally occurring airborne bacterial spores associated with spacecraft and their assembly areas has been hindered by lack of an effective collecting system. Efforts to collect and concentrate spores with air samplers or from air filters have not been successful. A fallout method was developed for this purpose and tested. Sterile Teflon ribbons (7.6 by 183 cm) were exposed in pertinent spacecraft assembly areas and subsequently treated with dry heat. Thermal inactivation experiments were conducted at 125 and 113 C. Heating intervals ranged from 1 to 12 h at 125 C and 6, 12, 18, and 24 h at 113 C. Eight hours was the longest heating time yielding survivors at 125 C, whereas survivors were recovered at all of the heating intervals at 113 C. D125C values were calculated using the fractional-replicate-unit-negative technique of Pflug and Schmidt (1968) and ranged from 25 to 126 min. This variation indicated that the most probable number of survivors at each heating interval did not fall on a straight line passing through the initial spore population. However, the most-probable-number values taken alone formed a straight line suggesting logarithmic thermal destruction of a subpopulation of spores with a D125C value of 6.3 h.

  15. Antimicrobial potential of Halophilic actinomycetes against multi drug resistant (MDR) ventilator associated pneumonia causing bacterial pathogens.

    PubMed

    Aslam, Sana; Sajid, Imran

    2016-03-01

    A collection of forty halophilic actinomycetes isolated from water and mud samples of the saline lake at Kalar Kahar, salt range, Pakistan, was screened to investigate their antimicrobial potential against multi drug resistant (MDR) ventilator associated pneumonia causing bacterial pathogens. The isolates exhibited significant tolerance to alkaline conditions and grew well at pH 9-11. The taxonomic status of the isolated strains was determined by morphological, biochemical and physiological characterization and by 16s rRNA gene sequencing. The results revealed that majority of the isolates (90%) belong to the genus Streptomyces. Most of the isolates exhibited remarkable antimicrobial activity up to 20mm zone of inhibition against MDR ventilator associated pneumonia causing bacteria including Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris, Klebsiella pneumoniae, Escherichia coli, Enterobacter and Acinetobacter spp. Additionally the isolates showed moderate to high cytotoxicity in the range of 40 to 80% larval mortality against Artemia salina in a micro well cytotoxicity assay. The chemical screening or the so called metabolic fingerprinting of the methanolic extracts of each isolate, by thin layer chromatography (TLC) using various staining reagents and by high performance liquid chromatography (HPLC-UV), indicated an impressive diversity of the compounds produced by these strains. The study reveals that these halophilic actinomycetes are a promising source of bioactive compounds. The preparative scale fermentation, isolation, purification and structure elucidation of the compounds produced by them may yield novel antimicrobial or chemotherapeutic agents.

  16. An efficient system for intracellular delivery of beta-lactam antibiotics to overcome bacterial resistance

    PubMed Central

    Abed, Nadia; Saïd-Hassane, Fatouma; Zouhiri, Fatima; Mougin, Julie; Nicolas, Valérie; Desmaële, Didier; Gref, Ruxandra; Couvreur, Patrick

    2015-01-01

    The “Golden era” of antibiotics is definitely an old story and this is especially true for intracellular bacterial infections. The poor intracellular bioavailability of antibiotics reduces the efficency of many treatments and thereby promotes resistances. Therefore, the development of nanodevices coupled with antibiotics that are capable of targeting and releasing the drug into the infected-cells appears to be a promising solution to circumvent these complications. Here, we took advantage of two natural terpenes (farnesyl and geranyl) to design nanodevices for an efficient intracellular delivery of penicillin G. The covalent linkage between the terpene moieties and the antibiotic leads to formation of prodrugs that self-assemble to form nanoparticles with a high drug payload between 55–63%. Futhermore, the addition of an environmentally-sensitive bond between the antibiotic and the terpene led to an efficient antibacterial activity against the intracellular pathogen Staphylococcus aureus with reduced intracellular replication of about 99.9% compared to untreated infected cells. Using HPLC analysis, we demonstrated and quantified the intracellular release of PenG when this sensitive-bond (SB) was present on the prodrug, showing the success of this technology to deliver antibiotics directly into cells. PMID:26311631

  17. Effect of different biochars on antibiotic resistance genes and bacterial community during chicken manure composting.

    PubMed

    Cui, Erping; Wu, Ying; Zuo, Yiru; Chen, Hong

    2016-03-01

    Rice straw biochar (RSB) and mushroom biochar (MB) were added to lab-scale chicken manure composting to evaluate their effects on the behaviors of antibiotic resistance genes (ARGs) and on total and bio-available heavy metals (Cu, Zn and As). The associated bacterial community was characterized by 16SrRNA high-throughput sequencing. The abundance of pathogenic bacteria was also calculated. At the end of the control composting experiment, the average removal rate of ARGs was 0.86 log units and the removal rate of pathogenic bacteria was 57.1%. MB addition resulted in a higher removal rate than that in the control composting experiment. However, RSB addition yielded opposite results, which may be due to the higher abundance of Erysipelotrichaceae, Lactobacillaceae, Family_XI_Incertae_Sedis (belonging to Firmicutes carrying and disseminating ARGs) and pathogenic bacteria carrying ARGs. Furthermore, the correlations between bio-available heavy metals and ARGs were more obvious than those between total heavy metals and ARGs.

  18. The Surface Layer of Tannerella forsythia Contributes to Serum Resistance and Oral Bacterial Coaggregation

    PubMed Central

    Shimotahira, Naohiro; Oogai, Yuichi; Kawada-Matsuo, Miki; Yamada, Sakuo; Fukutsuji, Kenji; Nagano, Keiji; Yoshimura, Fuminobu; Noguchi, Kazuyuki

    2013-01-01

    Tannerella forsythia is an anaerobic, Gram-negative bacterium involved in the so-called “red complex,” which is associated with severe and chronic periodontitis. The surface layer (S-layer) of T. forsythia is composed of cell surface glycoproteins, such as TfsA and TfsB, and is known to play a role in adhesion/invasion and suppression of proinflammatory cytokine expression. Here we investigated the association of this S-layer with serum resistance and coaggregation with other oral bacteria. The growth of the S-layer-deficient mutant in a bacterial medium containing more than 20% non-heat-inactivated calf serum (CS) or more than 40% non-heat-inactivated human serum was significantly suppressed relative to that of the wild type (WT). Next, we used confocal microscopy to perform quantitative analysis on the effect of serum. The survival ratio of the mutant exposed to 100% non-heat-inactivated CS (76% survival) was significantly lower than that of the WT (97% survival). Furthermore, significant C3b deposition was observed in the mutant but not in the WT. In a coaggregation assay, the mutant showed reduced coaggregation with Streptococcus sanguinis, Streptococcus salivarius, and Porphyromonas gingivalis but strong coaggregation with Fusobacterium nucleatum. These results indicated that the S-layer of T. forsythia plays multiple roles in virulence and may be associated with periodontitis. PMID:23357386

  19. Epidemiology and burden of multidrug-resistant bacterial infection in a developing country

    PubMed Central

    Lim, Cherry; Takahashi, Emi; Hongsuwan, Maliwan; Wuthiekanun, Vanaporn; Thamlikitkul, Visanu; Hinjoy, Soawapak; Day, Nicholas PJ; Peacock, Sharon J; Limmathurotsakul, Direk

    2016-01-01

    Little is known about the excess mortality caused by multidrug-resistant (MDR) bacterial infection in low- and middle-income countries (LMICs). We retrospectively obtained microbiology laboratory and hospital databases of nine public hospitals in northeast Thailand from 2004 to 2010, and linked these with the national death registry to obtain the 30-day mortality outcome. The 30-day mortality in those with MDR community-acquired bacteraemia, healthcare-associated bacteraemia, and hospital-acquired bacteraemia were 35% (549/1555), 49% (247/500), and 53% (640/1198), respectively. We estimate that 19,122 of 45,209 (43%) deaths in patients with hospital-acquired infection due to MDR bacteria in Thailand in 2010 represented excess mortality caused by MDR. We demonstrate that national statistics on the epidemiology and burden of MDR in LMICs could be improved by integrating information from readily available databases. The prevalence and mortality attributable to MDR in Thailand are high. This is likely to reflect the situation in other LMICs. DOI: http://dx.doi.org/10.7554/eLife.18082.001 PMID:27599374

  20. Exogenous l-Valine Promotes Phagocytosis to Kill Multidrug-Resistant Bacterial Pathogens

    PubMed Central

    Chen, Xin-hai; Liu, Shi-rao; Peng, Bo; Li, Dan; Cheng, Zhi-xue; Zhu, Jia-xin; Zhang, Song; Peng, Yu-ming; Li, Hui; Zhang, Tian-tuo; Peng, Xuan-xian

    2017-01-01

    The emergence of multidrug-resistant bacteria presents a severe threat to public health and causes extensive losses in livestock husbandry and aquaculture. Effective strategies to control such infections are in high demand. Enhancing host immunity is an ideal strategy with fewer side effects than antibiotics. To explore metabolite candidates, we applied a metabolomics approach to investigate the metabolic profiles of mice after Klebsiella pneumoniae infection. Compared with the mice that died from K. pneumoniae infection, mice that survived the infection displayed elevated levels of l-valine. Our analysis showed that l-valine increased macrophage phagocytosis, thereby reducing the load of pathogens; this effect was not only limited to K. pneumoniae but also included Escherichia coli clinical isolates in infected tissues. Two mechanisms are involved in this process: l-valine activating the PI3K/Akt1 pathway and promoting NO production through the inhibition of arginase activity. The NO precursor l-arginine is necessary for l-valine-stimulated macrophage phagocytosis. The valine-arginine combination therapy effectively killed K. pneumoniae and exerted similar effects in other Gram-negative (E. coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. Our study extends the role of metabolism in innate immunity and develops the possibility of employing the metabolic modulator-mediated innate immunity as a therapy for bacterial infections. PMID:28321214

  1. Past, Present, and Future of Antibacterial Economics: Increasing Bacterial Resistance, Limited Antibiotic Pipeline, and Societal Implications.

    PubMed

    Luepke, Katherine H; Suda, Katie J; Boucher, Helen; Russo, Rene L; Bonney, Michael W; Hunt, Timothy D; Mohr, John F

    2017-01-01

    Growing antimicrobial resistance and a dwindling antibiotic pipeline have resulted in an emerging postantibiotic era, as patients are now dying from bacterial infections that were once treatable. The fast-paced "Golden Age" of antibiotic development that started in the 1940s has lost momentum; from the 1980s to the early 2000s, there was a 90% decline in the approval of new antibiotics as well as the discovery of few new novel classes. Many companies have shifted away from development due to scientific, regulatory, and economic hurdles that proved antibiotic development to be less attractive compared with more lucrative therapeutic areas. National and global efforts are focusing attention toward potential solutions for reinvigorating the antibiotic pipeline and include "push" incentives such as public-private partnerships and "pull" incentives such as reimbursement reform and market exclusivity. Hybrid models of incentives, global coordination among stakeholders, and the appropriate balance of antibiotic pricing, volume of drug used, and proper antimicrobial stewardship are key to maximizing efforts toward drug development to ensure access to patients in need of these therapies.

  2. The inflammasomes: molecular effectors of host resistance against bacterial, viral, parasitic, and fungal infections.

    PubMed

    Skeldon, Alexander; Saleh, Maya

    2011-01-01

    The inflammasomes are large multi-protein complexes scaffolded by cytosolic pattern recognition receptors (PRRs) that form an important part of the innate immune system. They are activated following the recognition of microbial-associated molecular patterns or host-derived danger signals (danger-associated molecular patterns) by PRRs. This recognition results in the recruitment and activation of the pro-inflammatory protease caspase-1, which cleaves its preferred substrates pro-interleukin-1β (IL-1β) and pro-IL-18 into their mature biologically active cytokine forms. Through processing of a number of other cellular substrates, caspase-1 is also required for the release of "alarmins" and the induction and execution of an inflammatory form of cell death termed pyroptosis. A growing spectrum of inflammasomes have been identified in the host defense against a variety of pathogens. Reciprocally, pathogens have evolved effector strategies to antagonize the inflammasome pathway. In this review we discuss recent developments in the understanding of inflammasome-mediated recognition of bacterial, viral, parasitic, and fungal infections and the beneficial or detrimental effects of inflammasome signaling in host resistance.

  3. [Using kenaf (Hibiscus cannabinus) to reclaim multi-metal contaminated acidic soil].

    PubMed

    Yang, Yu-Xi; Lu, Huan-Liang; Zhan, Shu-Shun; Deng, Teng-hao-bo; Lin, Qing-Qi; Wang, Shi-Zhong; Yang, Xiu-Hong; Qiu, Rong-Liang

    2013-03-01

    A five-year field trial was conducted at the surrounding area of Dabao Mountain Mine to explore the feasibility and availability of using kenaf (Hibiscus cannabinus) , a fiber crop with strong heavy metals tolerance and potential economic value, to reclaim the multi-metal contaminated acidic farmland soil. Different amendments were applied prior to the kenaf planting to evaluate their effects on the soil properties and kenaf growth. After the amendments application, the kenaf could grow well on the heavy metals contaminated soil with the Pb, Zn, Cu, Cd, and As concentrations being 1600, 440, 640, 7. 6, and 850 mg . kg-1, respectively. Among the amendments, dolomite and fly ash had better effects than limestone and organic fertilizer. With the application of dolomite and fly ash, the aboveground dry mass production of kenaf reached 14-15 t . hm-2, which was similar to that on normal soils, and the heavy metal concentrations in the bast fiber and stem of kenaf decreased significantly, as compared with the control. The mass of the bast fiber accounted for 32% -38% of the shoot production, and the extractable heavy metal concentrations in the bast fiber could meet the standard of 'technical specifications of ecological textiles' in China, suggesting that the bast fiber had potential economic value. It was suggested that planting kenaf combining with dolomite/fly ash application could be an effective measure to reclaim the multi-metal contaminated acidic farmland soil.

  4. Development and evaluation of a new multi-metal binding biosorbent.

    PubMed

    Abdolali, A; Ngo, H H; Guo, W S; Lee, D J; Tung, K L; Wang, X C

    2014-05-01

    A novel multi-metal binding biosorbent (MMBB) was developed by combining a group of three from the selective natural lignocellulosic agro-industrial wastes for effectively eliminating lead, cadmium, copper and zinc from aqueous solutions. Four MMBBs with different combinations (MMBB1: tea waste, corncob, sugarcane bagasse; MMBB2: tea waste, corncob and sawdust; MMBB3: tea waste, corncob and apple peel; MMBB4: tea waste, corncob and grape stalk) were evaluated. FTIR analysis for characterizing the MMBB2 explored that the MMBB2 contains more functional groups available for multi-metals binding. Comparing among the MMBBs as well as the single group biosorbents, MMBB2 was the best biosorbent with the maximum biosorption capacities of 41.48, 39.48, 94.00 and 27.23 mg/g for Cd(II), Cu(II), Pb(II) and Zn(II), respectively. After 5 times of desorption with CaCl2, CH3COOH and NaCl as eluent, the MMBB2 still remained excellent biosorptive capacity, so as it could be well regenerated for reuse and possible recovery of metals.

  5. Induction of Xa10-like genes in rice cultivar Nipponbare confers disease resistance to rice bacterial blight.

    PubMed

    Wang, Jun; Tian, Dongsheng; Gu, Keyu; Yang, Xiaobei; Wang, Lanlan; Zeng, Xuan; Yin, Zhongchao

    2017-03-17

    Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive bacterial diseases throughout the major rice growing regions in the world. The rice disease resistance (R) genes Xa10 confers race-specific disease resistance to X. oryzae pv. oryzae strains that deliver the corresponding transcription activator-like (TAL) effectors AvrXa10. Upon bacterial infection, AvrXa10 binds specifically to the effector binding element (EBE) in the promoter of the R gene and activates its expression. Xa10 encodes an executor R protein that triggers hypersensitive response and activates disease resistance. Rice cultivar Nipponbare carries two Xa10-like genes in its genome, of which one is the susceptible allele of the Xa23 gene, a Xa10-like TAL effector-dependent executor R gene isolated recently from rice cultivar CBB23. However, the function of the two Xa10-like genes in disease resistance to X. oryzae pv. oryzae strains has not been investigated. Here we designated the two Xa10-like genes as Xa10-Ni and Xa23-Ni and characterized their function for disease resistance to rice bacterial blight. Both Xa10-Ni and Xa23-Ni provided disease resistance to X. oryzae pv. oryzae strains that deliver the matching artificially designed TAL effectors (dTALEs). Transgenic rice plants containing Xa10-Ni and Xa23-Ni under the Xa10 promoter provided specific disease resistance to X. oryzae pv. oryzae strains that deliver AvrXa10. Xa10-Ni and Xa23-Ni knock-out mutants abolished dTALE-dependent disease resistance to X. oryzae pv. oryzae. Heterologous expression of Xa10-Ni and Xa23-Ni in Nicotiana benthamiana triggered cell death. The 19-amino acid residues at the N-terminal regions of XA10 or XA10-Ni are dispensable for their function in inducing cell death in N. benthamiana and the C-terminal regions of XA10, XA10-Ni and XA23-Ni are interchangeable among each other without affecting their function. Like XA10, both XA10-Ni and XA23-Ni locate to the endoplasmic

  6. Prevalence of bacterial pathogens and their anti-microbial resistance in Tilapia and their pond water in Trinidad.

    PubMed

    Newaj-Fyzul, A; Mutani, A; Ramsubhag, A; Adesiyun, A

    2008-05-01

    In Trinidad, Tilapia (Oreonchromis spp.) is one of the most important fresh water food fish and the number of farms has been increasing annually. A study was conducted in the local tilapia industry to determine the microbial quality of pond water, prevalence of bacterial pathogens and their anti-microbial resistance using the disk diffusion method. Seventy-five apparently healthy fish and 15 pond water samples from three of the four commercial tilapia fish farms in the country were processed. The 202 bacterial isolates recovered from fish slurry and 88 from water, belonged to 13 and 16 genera respectively. The predominant bacteria from fish slurry were Pseudomonas spp. (60.0%), Aeromonas spp. (44.0%), Plesiomonas (41.3%) and Chromobacterium (36.0%) (P < 0.05; chi(2)) compared with isolates from pond water where Bacillus spp. (80.0%), Staphylococcus spp., Alcaligenes spp. and Aeromonas spp. (60.0%) were most prevalent (P < 0.05; chi(2)). Using eight anti-microbial agents, to test bacteria from five genera (Aeromonas, Chromobacterium, Enterobacter, Plesiomonas and Pseudomonas), 168 (97.1%) of 173 bacterial isolates from fish slurry exhibited resistance to one or more anti-microbial agents compared with 47 (90.4%) of 52 from water (P > 0.05; chi(2)). Resistance was high to ampicillin, 90.2% (158 of 173), erythromycin, 66.5% (115 of 173) and oxytetracycline, 52.6%, (91 of 173) but relatively low to chloramphenicol, 9.8% (17 of 173) and sulphamethoxazole/trimethoprim, 6.4% (11 of 173) (P < 0.05; chi(2)). For pond water isolates, the frequency of resistance across bacterial genera ranged from 75% (nine of 12) for Chromobacter spp. to 100% found amongst Enterobacter spp. (six of six), Plesiomonas spp. (nine of nine) and Pseudomonas spp. (eight of eight) (P < 0.05; chi(2)). Resistance was generally high to ampicillin, 78.8% (41 of 52), erythromycin, 51.9% (27 of 52) and oxytetracycline, 34.5% (18 of 52) but low to sulphamethoxazole/trimethoprim, 7.7% (four of 52) and

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

    PubMed

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

    2010-10-01

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

  8. D-Psicose induces upregulation of defense-related genes and resistance in rice against bacterial blight.

    PubMed

    Kano, Akihito; Hosotani, Kouji; Gomi, Kenji; Yamasaki-Kokudo, Yumiko; Shirakawa, Chikage; Fukumoto, Takeshi; Ohtani, Kouhei; Tajima, Shigeyuki; Izumori, Ken; Tanaka, Keiji; Ishida, Yutaka; Nishizawa, Yoko; Ichimura, Kazuya; Tada, Yasuomi; Akimitsu, Kazuya

    2011-10-15

    We examined rice responses to a rare sugar, d-psicose. Rice growth was inhibited by d-psicose but not by common sugars. Microarray analysis revealed that d-psicose treatment caused an upregulation of many defense-related genes in rice, and dose-dependent upregulation of these genes was confirmed by quantitative reverse-transcription polymerase chain reaction. The level of upregulation of defense-related genes by d-psicose was low compared with that by d-allose, which is another rare sugar known to confer induction of resistance to rice bacterial blight in rice. Treatment with d-psicose conferred resistance to bacterial blight in rice in a dose-dependent manner, and the results indicate that d-psicose might be a candidate plant activator for reducing disease development in rice.

  9. Empirical modeling of heavy metal extraction by EDDS from single-metal and multi-metal contaminated soils.

    PubMed

    Yip, Theo C M; Tsang, Daniel C W; Ng, Kelvin T W; Lo, Irene M C

    2009-01-01

    The effectiveness of using biodegradable EDDS (S,S-ethylenediaminedisuccinic acid) for metal extraction has drawn increasing attention in recent years. In this study, an empirical model, which utilized the initial metal distribution in soils and a set of parameter values independently determined from sequential extraction, was developed for estimating the time-dependent heavy metal extraction by EDDS from single-metal and multi-metal contaminated soils. The model simulation provided a satisfactory description of the experimental results of the 7-d extraction kinetics of Cu, Zn, and Pb in both artificially contaminated and field-contaminated soils. Thus, independent and prior assessment of extraction efficiency would be available to facilitate the engineering applications of EDDS. Furthermore, a simple empirical equation using the initial metal distribution was also proposed to estimate the extraction efficiency at equilibrium. It was found that, for the same type of soils, higher extraction efficiency was achieved in multi-metal contaminated soils than in single-metal contaminated soils. The differences were 4-9%, 9-16%, and 21-31% for Cu, Zn, and Pb, respectively, probably due to the larger proportion of exchangeable and carbonate fractions of sorbed Zn and Pb in multi-metal contaminated soils. EDDS-promoted mineral dissolution, on the other hand, was more significant in multi-metal contaminated soils as a result of the higher EDDS concentration applied to the soils of higher total metal content.

  10. Bacteriophage resistance mechanisms in the fish pathogen Flavobacterium psychrophilum: linking genomic mutations to changes in bacterial virulence factors.

    PubMed

    Castillo, Daniel; Christiansen, Rói Hammershaimb; Dalsgaard, Inger; Madsen, Lone; Middelboe, Mathias

    2015-02-01

    Flavobacterium psychrophilum is an important fish pathogen in salmonid aquaculture worldwide. Due to increased antibiotic resistance, pathogen control using bacteriophages has been explored as a possible alternative treatment. However, the effective use of bacteriophages in pathogen control requires overcoming the selection for phage resistance in the bacterial populations. Here, we analyzed resistance mechanisms in F. psychrophilum after phage exposure using whole-genome sequencing of the ancestral phage-sensitive strain 950106-1/1 and six phage-resistant isolates. The phage-resistant strains had all obtained unique insertions and/or deletions and point mutations distributed among intergenic and genic regions. Mutations in genes related to cell surface properties, gliding motility, and biosynthesis of lipopolysaccharides and cell wall were found. The observed links between phage resistance and the genetic modifications were supported by direct measurements of bacteriophage adsorption rates, biofilm formation, and secretion of extracellular enzymes, which were all impaired in the resistant strains, probably due to superficial structural changes. The clustered regularly interspaced short palindromic repeat (CRISPR) region was unaffected in the resistant isolates and thus did not play a role as a resistance mechanism for F. psychrophilum under the current conditions. All together, the results suggest that resistance in F. psychrophilum was driven by spontaneous mutations, which were associated with a number of derived effects on the physiological properties of the pathogen, including reduced virulence under in vitro conditions. Consequently, phage-driven physiological changes associated with resistance may have implications for the impact of the pathogen in aquaculture, and these effects of phage resistance on host properties are therefore important for the ongoing exploration of phage-based control of F. psychrophilum.

  11. Molecular characterization of conjugative plasmids in pesticide tolerant and multi-resistant bacterial isolates from contaminated alluvial soil.

    PubMed

    Anjum, Reshma; Grohmann, Elisabeth; Malik, Abdul

    2011-06-01

    A total of 35 bacteria from contaminated soil (cultivated fields) near pesticide industry from Chinhat, Lucknow, (India) were isolated and tested for their tolerance/resistance to pesticides, heavy metals and antibiotics. Bacterial isolates were identified by 16S rDNA sequencing. Gas Chromatography analysis of the soil samples revealed the presence of lindane at a concentration of 547 ng g(-1) and α-endosulfan and β-endosulfan of 422 ng g(-1) and 421 ng g(-1) respectively. Atomic Absorption Spectrophotometry analysis of the test sample was done and Cr, Zn, Ni, Fe, Cu and Cd were detected at concentrations of 36.2, 42.5, 43.2, 241, 13.3 and 11.20 mg kg(-1) respectively. Minimum inhibitory concentrations of all the isolates were determined for pesticides and heavy metals. All the multi-resistant/tolerant bacterial isolates were also tested for the presence of incompatibility (Inc) group IncP, IncN, IncW, IncQ plasmids and for rolling circle plasmids of the pMV158-family by PCR. Total community DNA was extracted from pesticide contaminated soil. PCR amplification of the bacterial isolates and soil DNA revealed the presence of IncP-specific sequences (trfA2 and oriT) which was confirmed by dot blot hybridization with RP4-derived DIG-labelled probes. Plasmids belonging to IncN, IncW and IncQ group were neither detected in the bacterial isolates nor in total soil DNA. The presence of conjugative or mobilizable IncP plasmids in the isolates indicate that these bacteria have gene transfer capacity with implications for dissemination of heavy metal and antibiotic resistance genes. We propose that IncP plasmids are mainly responsible for the spread of multi-resistant bacteria in the contaminated soils.

  12. Nonviral Genome Editing Based on a Polymer-Derivatized CRISPR Nanocomplex for Targeting Bacterial Pathogens and Antibiotic Resistance.

    PubMed

    Kang, Yoo Kyung; Kwon, Kyu; Ryu, Jea Sung; Lee, Ha Neul; Park, Chankyu; Chung, Hyun Jung

    2017-02-27

    The overuse of antibiotics plays a major role in the emergence and spread of multidrug-resistant bacteria. A molecularly targeted, specific treatment method for bacterial pathogens can prevent this problem by reducing the selective pressure during microbial growth. Herein, we introduce a nonviral treatment strategy delivering genome editing material for targeting antibacterial resistance. We apply the CRISPR-Cas9 system, which has been recognized as an innovative tool for highly specific and efficient genome engineering in different organisms, as the delivery cargo. We utilize polymer-derivatized Cas9, by direct covalent modification of the protein with cationic polymer, for subsequent complexation with single-guide RNA targeting antibiotic resistance. We show that nanosized CRISPR complexes (= Cr-Nanocomplex) were successfully formed, while maintaining the functional activity of Cas9 endonuclease to induce double-strand DNA cleavage. We also demonstrate that the Cr-Nanocomplex designed to target mecA-the major gene involved in methicillin resistance-can be efficiently delivered into Methicillin-resistant Staphylococcus aureus (MRSA), and allow the editing of the bacterial genome with much higher efficiency compared to using native Cas9 complexes or conventional lipid-based formulations. The present study shows for the first time that a covalently modified CRISPR system allows nonviral, therapeutic genome editing, and can be potentially applied as a target specific antimicrobial.

  13. Temporal and multiple quantitative trait loci analyses of resistance to bacterial wilt in tomato permit the resolution of linked loci.

    PubMed Central

    Mangin, B; Thoquet, P; Olivier, J; Grimsley, N H

    1999-01-01

    Ralstonia solanacearum is a soil-borne bacterium that causes the serious disease known as bacterial wilt in many plant species. In tomato, several QTL controlling resistance have been found, but in different studies, markers spanning a large region of chromosome 6 showed strong association with the resistance. By using two different approaches to analyze the data from a field test F3 population, we show that at least two separate loci approximately 30 cM apart on this chromosome are most likely involved in the resistance. First, a temporal analysis of the progression of symptoms reveals a distal locus early in the development of the disease. As the disease progresses, the maximum LOD peak observed shifts toward the proximal end of the chromosome, obscuring the distal locus. Second, although classical interval mapping could only detect the presence of one locus, a statistical "two-QTL model" test, specifically adapted for the resolution of linked QTL, strongly supported the hypothesis for the presence of two loci. These results are discussed in the context of current molecular knowledge about disease resistance genes on chromosome 6 and observations made by tomato breeders during the production of bacterial wilt-resistant varieties. PMID:10049932

  14. Temporal and multiple quantitative trait loci analyses of resistance to bacterial wilt in tomato permit the resolution of linked loci.

    PubMed

    Mangin, B; Thoquet, P; Olivier, J; Grimsley, N H

    1999-03-01

    Ralstonia solanacearum is a soil-borne bacterium that causes the serious disease known as bacterial wilt in many plant species. In tomato, several QTL controlling resistance have been found, but in different studies, markers spanning a large region of chromosome 6 showed strong association with the resistance. By using two different approaches to analyze the data from a field test F3 population, we show that at least two separate loci approximately 30 cM apart on this chromosome are most likely involved in the resistance. First, a temporal analysis of the progression of symptoms reveals a distal locus early in the development of the disease. As the disease progresses, the maximum LOD peak observed shifts toward the proximal end of the chromosome, obscuring the distal locus. Second, although classical interval mapping could only detect the presence of one locus, a statistical "two-QTL model" test, specifically adapted for the resolution of linked QTL, strongly supported the hypothesis for the presence of two loci. These results are discussed in the context of current molecular knowledge about disease resistance genes on chromosome 6 and observations made by tomato breeders during the production of bacterial wilt-resistant varieties.

  15. Microbiological quality of indoor and outdoor swimming pools in Greece: investigation of the antibiotic resistance of the bacterial isolates.

    PubMed

    Papadopoulou, Chrissanthy; Economou, Vangelis; Sakkas, Hercules; Gousia, Panagiota; Giannakopoulos, X; Dontorou, Catherine; Filioussis, George; Gessouli, Helen; Karanis, Panagiotis; Leveidiotou, Stamatina

    2008-07-01

    During 1997-2005, the microbiological quality and susceptibility of bacterial isolates of swimming pool waters were investigated. A total of 462 water samples were collected from three indoor swimming pools (a teaching pool, a competition public pool, a hydrotherapy pool) and two outdoor swimming pools (a hotel semi-public and a residential private pool) in Northwestern Greece. All water samples were analyzed for the presence of bacteria, protozoa and fungi and susceptibility tests were performed for the bacterial isolates. Sixty-seven percent of the examined water samples conformed to the microbiological standards and 32.9% exceeded at least one of the indicated limits. Out of 107 bacterial isolates, 38 (35.5%) resistant strains were detected. Multi-resistant Pseudomonas alcaligenes, Leuconostoc, and Staphylococcus aureus (isolated from the teaching pool), Staphylococcus wernerii, Chryseobacterium indologenes and Ochrobactrum anthropi (isolated from the competition pool), Pseudomonas aeruginosa, P. fluorescens, Aeromonas hydrophila, Enterobacter cloacae, Klebsiella pneumoniae and S. aureus (isolated from the hydrotherapy pool) and A. hydrophila (isolated from the hotel pool) were detected. The swimming pool with the poorest microbiological quality (THC 500 cfu/ml in 12.1% of the samples, P. aeruginosa counts 1500 cfu/100 ml in 6% of the samples) and the highest prevalence of multi-resistant isolates (73.6%) was the hydrotherapy pool. No Cryptosporidium or Giardia cysts and no Legionella, Mycobacteria and Salmonella were detected, but there were isolations of Candida albicans, Aspergillus spp., Mucor spp., Alternaria spp., Rhizopus spp., Trichophyton spp., and Penicillium spp.

  16. Association mapping of common bacterial blight resistance QTL in Ontario bean breeding populations

    PubMed Central

    2011-01-01

    Background Common bacterial blight (CBB), incited by Xanthomonas axonopodis pv. phaseoli (Xap), is a major yield-limiting factor of common bean (Phaseolus vulgaris L.) production around the world. Host resistance is practically the most effective and environmentally-sound approach to control CBB. Unlike conventional QTL discovery strategies, in which bi-parental populations (F2, RIL, or DH) need to be developed, association mapping-based strategies can use plant breeding populations to synchronize QTL discovery and cultivar development. Results A population of 469 dry bean lines of different market classes representing plant materials routinely developed in a bean breeding program were used. Of them, 395 lines were evaluated for CBB resistance at 14 and 21 DAI (Days After Inoculation) in the summer of 2009 in an artificially inoculated CBB nursery in south-western Ontario. All lines were genotyped using 132 SNPs (Single Nucleotide Polymorphisms) evenly distributed across the genome. Of the 132 SNPs, 26 SNPs had more than 20% missing data, 12 SNPs were monomorphic, and 17 SNPs had a MAF (Minor Allelic Frequency) of less than 0.20, therefore only 75 SNPs were used for association study, based on one SNP per locus. The best possible population structure was to assign 36% and 64% of the lines into Andean and Mesoamerican subgroups, respectively. Kinship analysis also revealed complex familial relationships among all lines, which corresponds with the known pedigree history. MLM (Mixed Linear Model) analysis, including population structure and kinship, was used to discover marker-trait associations. Eighteen and 22 markers were significantly associated with CBB rating at 14 and 21 DAI, respectively. Fourteen markers were significant for both dates and the markers UBC420, SU91, g321, g471, and g796 were highly significant (p ≤ 0.001). Furthermore, 12 significant SNP markers were co-localized with or close to the CBB-QTLs identified previously in bi-parental QTL mapping

  17. TaCPK2-A, a calcium-dependent protein kinase gene that is required for wheat powdery mildew resistance enhances bacterial blight resistance in transgenic rice.

    PubMed

    Geng, Shuaifeng; Li, Aili; Tang, Lichuan; Yin, Lingjie; Wu, Liang; Lei, Cailin; Guo, Xiuping; Zhang, Xin; Jiang, Guanghuai; Zhai, Wenxue; Wei, Yuming; Zheng, Youliang; Lan, Xiujin; Mao, Long

    2013-08-01

    Calcium-dependent protein kinases (CPKs) are important Ca2+ signalling components involved in complex immune and stress signalling networks; but the knowledge of CPK gene functions in the hexaploid wheat is limited. Previously, TaCPK2 was shown to be inducible by powdery mildew (Blumeria graminis tritici, Bgt) infection in wheat. Here, its functions in disease resistance are characterized further. This study shows the presence of defence-response and cold-response cis-elements on the promoters of the A subgenome homoeologue (TaCPK2-A) and D subgenome homoeologue (TaCPK2-D), respectively. Their expression patterns were then confirmed by quantitative real-time PCR (qRT-PCR) using genome-specific primers, where TaCPK2-A was induced by Bgt treatment while TaCPK2-D mainly responded to cold treatment. Downregulation of TaCPK2-A by virus-induced gene silencing (VIGS) causes loss of resistance to Bgt in resistant wheat lines, indicating that TaCPK2-A is required for powdery mildew resistance. Furthermore, overexpression of TaCPK2-A in rice enhanced bacterial blight (Xanthomonas oryzae pv. oryzae, Xoo) resistance. qRT-PCR analysis showed that overexpression of TaCPK2-A in rice promoted the expression of OsWRKY45-1, a transcription factor involved in both fungal and bacterial resistance by regulating jasmonic acid and salicylic acid signalling genes. The opposite effect was found in wheat TaCPK2-A VIGS plants, where the homologue of OsWRKY45-1 was significantly repressed. These data suggest that modulation of WRKY45-1 and associated defence-response genes by CPK2 genes may be the common mechanism for multiple disease resistance in grass species, which may have undergone subfunctionalization in promoters before the formation of hexaploid wheat.

  18. TaCPK2-A, a calcium-dependent protein kinase gene that is required for wheat powdery mildew resistance enhances bacterial blight resistance in transgenic rice

    PubMed Central

    Geng, Shuaifeng; Li, Aili; Tang, Lichuan; Lan, Xiujin; Mao, Long

    2013-01-01

    Calcium-dependent protein kinases (CPKs) are important Ca2+ signalling components involved in complex immune and stress signalling networks; but the knowledge of CPK gene functions in the hexaploid wheat is limited. Previously, TaCPK2 was shown to be inducible by powdery mildew (Blumeria graminis tritici, Bgt) infection in wheat. Here, its functions in disease resistance are characterized further. This study shows the presence of defence-response and cold-response cis-elements on the promoters of the A subgenome homoeologue (TaCPK2-A) and D subgenome homoeologue (TaCPK2-D), respectively. Their expression patterns were then confirmed by quantitative real-time PCR (qRT-PCR) using genome-specific primers, where TaCPK2-A was induced by Bgt treatment while TaCPK2-D mainly responded to cold treatment. Downregulation of TaCPK2-A by virus-induced gene silencing (VIGS) causes loss of resistance to Bgt in resistant wheat lines, indicating that TaCPK2-A is required for powdery mildew resistance. Furthermore, overexpression of TaCPK2-A in rice enhanced bacterial blight (Xanthomonas oryzae pv. oryzae, Xoo) resistance. qRT-PCR analysis showed that overexpression of TaCPK2-A in rice promoted the expression of OsWRKY45-1, a transcription factor involved in both fungal and bacterial resistance by regulating jasmonic acid and salicylic acid signalling genes. The opposite effect was found in wheat TaCPK2-A VIGS plants, where the homologue of OsWRKY45-1 was significantly repressed. These data suggest that modulation of WRKY45-1 and associated defence-response genes by CPK2 genes may be the common mechanism for multiple disease resistance in grass species, which may have undergone subfunctionalization in promoters before the formation of hexaploid wheat. PMID:23918959

  19. Transcriptome of American oysters, Crassostrea virginica, in response to bacterial challenge: insights into potential mechanisms of disease resistance.

    PubMed

    McDowell, Ian C; Nikapitiya, Chamilani; Aguiar, Derek; Lane, Christopher E; Istrail, Sorin; Gomez-Chiarri, Marta

    2014-01-01

    The American oyster Crassostrea virginica, an ecologically and economically important estuarine organism, can suffer high mortalities in areas in the Northeast United States due to Roseovarius Oyster Disease (ROD), caused by the gram-negative bacterial pathogen Roseovarius crassostreae. The goals of this research were to provide insights into: 1) the responses of American oysters to R. crassostreae, and 2) potential mechanisms of resistance or susceptibility to ROD. The responses of oysters to bacterial challenge were characterized by exposing oysters from ROD-resistant and susceptible families to R. crassostreae, followed by high-throughput sequencing of cDNA samples from various timepoints after disease challenge. Sequence data was assembled into a reference transcriptome and analyzed through differential gene expression and functional enrichment to uncover genes and processes potentially involved in responses to ROD in the American oyster. While susceptible oysters experienced constant levels of mortality when challenged with R. crassostreae, resistant oysters showed levels of mortality similar to non-challenged oysters. Oysters exposed to R. crassostreae showed differential expression of transcripts involved in immune recognition, signaling, protease inhibition, detoxification, and apoptosis. Transcripts involved in metabolism were enriched in susceptible oysters, suggesting that bacterial infection places a large metabolic demand on these oysters. Transcripts differentially expressed in resistant oysters in response to infection included the immune modulators IL-17 and arginase, as well as several genes involved in extracellular matrix remodeling. The identification of potential genes and processes responsible for defense against R. crassostreae in the American oyster provides insights into potential mechanisms of disease resistance.

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

    PubMed

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

    2016-04-01

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

  1. High level multiple antibiotic resistance among fish surface associated bacterial populations in non-aquaculture freshwater environment.

    PubMed

    Ozaktas, Tugba; Taskin, Bilgin; Gozen, Ayse G

    2012-12-01

    Freshwater fish, Alburnus alburnus (bleak), were captured from Lake Mogan, situated in Ankara, during spring. The surface mucus of the fish was collected and associated bacteria were cultured and isolated. By sequencing PCR-amplified 16S RNA encoding genes, the isolates were identified as members of 12 different genera: Acinetobacter, Aeromonas, Bacillus, Brevundimonas, Gordonia, Kocuria, Microbacterium, Mycobacterium, Pseudomonas, Rhodococcus, and Staphylococcus, in addition to one strain that was unidentified. The mucus-dwelling bacterial isolates were tested for resistance against ampicillin, kanamycin, streptomycin and chloramphenicol. About 95% of the isolates were found to be resistant to ampicillin, 93% to chloramphenicol, and 88% to kanamycin and streptomycin. A Microbacterium oxydans and the unidentified environmental isolate were resistant to all four antibiotics tested at very high levels (>1600 μg/ml ampicillin and streptomycin; >1120 μg/ml kanamycin; >960 μg/ml chloramphenicol). Only a Kocuria sp. was sensitive to all four antibiotics at the lowest concentrations tested (3.10 μg/ml ampicillin and streptomycin; 2.15 μg/ml kanamycin; 1.85 μg/ml chloramphenicol). The rest of the isolates showed different resistance levels. Plasmid isolations were carried out to determine if the multiple antibiotic resistance could be attributed to the presence of plasmids. However, no plasmid was detected in any of the isolates. The resistance appeared to be mediated by chromosome-associated functions. This study indicated that multiple antibiotic resistance at moderate to high levels is common among the current phenotypes of the fish mucus-dwelling bacterial populations in this temperate, shallow lake which has not been subjected to any aquaculturing so far but under anthropogenic effect being in a recreational area.

  2. Experimental Sugar Beet Cultivars Evaluated for Resistance Bacterial Root Rot in Idaho, 2008

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial root rot of sugar beet caused by Leuconostoc mesenteroides subsp. dextranicum is a disease problem recently described in the United States. To ameliorate the impact of bacterial root rot on sucrose loss in the field, storage piles, and factories, a study was conducted to identify resistan...

  3. Expression of an evolved engineered variant of a bacterial glycine oxidase leads to glyphosate resistance in alfalfa.

    PubMed

    Nicolia, A; Ferradini, N; Molla, G; Biagetti, E; Pollegioni, L; Veronesi, F; Rosellini, D

    2014-08-20

    The main strategy for resistance to the herbicide glyphosate in plants is the overexpression of an herbicide insensitive, bacterial 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). A glyphosate resistance strategy based on the ability to degrade the herbicide can be useful to reduce glyphosate phytotoxicity to the crops. Here we present the characterization of glyphosate resistance in transgenic alfalfa (Medicago sativa L.) expressing a plant-optimized variant of glycine oxidase (GO) from Bacillus subtilis, evolved in vitro by a protein engineering approach to efficiently degrade glyphosate. Two constructs were used, one with (GO(TP+)) and one without (GO(TP-)) the pea rbcS plastid transit peptide. Molecular and biochemical analyses confirmed the stable integration of the transgene and the correct localization of the plastid-imported GO protein. Transgenic alfalfa plants were tested for glyphosate resistance both in vitro and in vivo. Two GO(TP+) lines showed moderate resistance to the herbicide in both conditions. Optimization of expression of this GO variant may allow to attain sufficient field resistance to glyphosate herbicides, thus providing a resistance strategy based on herbicide degradation.

  4. Root-associated bacterial endophytes from Ralstonia solanacearum resistant and susceptible tomato cultivars and their pathogen antagonistic effects

    PubMed Central

    Upreti, Reshmi; Thomas, Pious

    2015-01-01

    This study was undertaken to assess if the root-associated native bacterial endophytes in tomato have any bearing in governing the host resistance to the wilt pathogen Ralstonia solanacearum. Internal colonization of roots by bacterial endophytes was confirmed through confocal imaging after SYTO-9 staining. Endophytes were isolated from surface-sterilized roots of 4-weeks-old seedlings of known wilt resistant (R) tomato cultivar Arka Abha and susceptible (S) cv. Arka Vikas on nutrient agar after plating the tissue homogenate. Arka Abha displayed more diversity with nine distinct organisms while Arka Vikas showed five species with two common organisms (Pseudomonas oleovorans and Agrobacterium tumefaciens). Screening for general indicators of biocontrol potential showed more isolates from Arka Abha positive for siderophore, HCN and antibiotic biosynthesis than from Arka Vikas. Direct challenge against the pathogen indicated strong antagonism by three Arka Abha isolates (P. oleovorans, Pantoea ananatis, and Enterobacter cloacae) and moderate activity by three others, while just one isolate from Arka Vikas (P. oleovorans) showed strong antagonism. Validation for the presence of bacterial endophytes on three R cultivars (Arka Alok, Arka Ananya, Arka Samrat) showed 8–9 antagonistic bacteria in them in comparison with four species in the three S cultivars (Arka Ashish, Arka Meghali, Arka Saurabhav). Altogether 34 isolates belonging to five classes, 16 genera and 27 species with 23 of them exhibiting pathogen antagonism were isolated from the four R cultivars against 17 isolates under three classes, seven genera and 13 species from the four S cultivars with eight isolates displaying antagonistic effects. The prevalence of higher endophytic bacterial diversity and more antagonistic organisms associated with the seedling roots of resistant cultivars over susceptible genotypes suggest a possible role by the root-associated endophytes in natural defense against the pathogen

  5. Bacterial Epidemiology and Antimicrobial Resistance in the Surgery Wards of a Large Teaching Hospital in Southern Italy

    PubMed Central

    Esposito, Silvano; Gioia, Renato; De Simone, Giuseppe; Noviello, Silvana; Lombardi, Domenico; Di Crescenzo, Vincenzo Giuseppe; Filippelli, Amelia; Rega, Maria Rosaria; Massari, Angelo; Elberti, Maria Giovanna; Grisi, Lucilla; Boccia, Giovanni; De Caro, Francesco; Leone, Sebastiano

    2015-01-01

    Objectives Surgical infections represent an increasingly important problem for the National Health System. In this study we retrospectively evaluated the bacterial epidemiology and antimicrobial susceptibility of the microorganisms concerned as well as the utilization of antibiotics in the General and Emergency Surgery wards of a large teaching hospital in southern Italy in the period 2011–2013. Methods Data concerning non-duplicate bacterial isolates and antimicrobial susceptibility were retrieved from the Vitek 2 database. The pharmacy provided data about the consumption of antibiotics in the above reported wards. Chi-square or Fisher’s exact test were used. Results In all, 94 Gram-negative were isolated in 2011, 77 in 2012, and 125 in 2013, Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa always being the most frequently isolated microorganisms. A. baumannii showed high rates of resistance to carbapenems (with values of 100% in 2011 and 2012) and low rates of resistance to tigecycline, colistin and amikacin. In the same years, there were respectively 105, 93, and 165 Gram-positive isolated. The rate of MRSA isolates ranged from 66% to 75% during the study period. Conclusions Our results show no significant increase in antimicrobial resistance over the period in question, and a higher rate of both MRSA isolates and resistance to carbapenems in A. baumannii compared with other European data. PMID:26075047

  6. A novel, sensitive method to evaluate potato germplasm for bacterial wilt resistance using a luminescent Ralstonia solanacearum reporter strain.

    PubMed

    Cruz, Andrea Paola Zuluaga; Ferreira, Virginia; Pianzzola, María Julia; Siri, María Inés; Coll, Núria S; Valls, Marc

    2014-03-01

    Several breeding programs are under way to introduce resistance to bacterial wilt caused by Ralstonia solanacearum in solanaceous crops. The lack of screening methods allowing easy measurement of pathogen colonization and the inability to detect latent (i.e., symptomless) infections are major limitations when evaluating resistance to this disease in plant germplasm. We describe a new method to study the interaction between R. solanacearum and potato germplasm that overcomes these restrictions. The R. solanacearum UY031 was genetically modified to constitutively generate light from a synthetic luxCDABE operon stably inserted in its chromosome. Colonization of this reporter strain on different potato accessions was followed using life imaging. Bacterial detection in planta by this nondisruptive system correlated with the development of wilting symptoms. In addition, we demonstrated that quantitative detection of the recombinant strain using a luminometer can identify latent infections on symptomless potato plants. We have developed a novel, unsophisticated, and accurate method for high-throughput evaluation of pathogen colonization in plant populations. We applied this method to compare the behavior of potato accessions with contrasting resistance to R. solanacearum. This new system will be especially useful to detect latency in symptomless parental lines before their inclusion in long-term breeding programs for disease resistance.

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

    PubMed

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

    2009-05-01

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

  8. Amoxicillin/clavulanate (Augmentin) resistant Escherichia coli in bacterial peritonitis after abdominal surgery--clinical outcome in ICU patients.

    PubMed

    Rahnama'i, M S; Wagenvoort, J H T; van der Linden, C J

    2009-05-01

    Bacterial resistance to antimicrobial agents is of great concern to clinicians. Patient outcome after infection is mainly dependent on the sensitivity of the bacterium to the agent used. We retrospectively studied 89 postoperative intensive care unit (ICU) patients with proven Escherichia coli peritonitis and investigated the clinical consequences of the E. coli resistance to amoxicillin/clavulanate. Significantly increased mortality, days of ventilation and ICU stay were noted in the co-amoxicillin/clavulanate resistant group. Furthermore, our results demonstrate that the sensitivity of E. coli to amoxicillin/clavulanate in the postoperative ICU setting has decreased in recent years. We can conclude that the current antibiotic regimen for the empirical treatment of ICU patients with peritonitis, as used in our hospital, needs to be changed. A switch, for instance, to ceftriaxone (Rocephin) in combination with metronidazole and gentamicin, instead of the present regimen of amoxicillin/clavulanate in combination with gentamicin, seems preferable.

  9. Application of atomic absorption spectroscopy for detection of multimetal traces in low-voltage electrical marks.

    PubMed

    Jakubeniene, Marija; Zakaras, Algirdas; Minkuviene, Zita Nijole; Benoshys, Alvydas

    2006-08-10

    Application of atomic absorption spectroscopy to detect multimetal traces in injured skin is a promising tool for investigation of fatalities caused by electrocution. The present paper is aimed at testing the reliability of this method for metal traces detection in electric current marks and is focused on study of peculiarities of metal penetration into the skin exposed to a current impact. Bare aluminum wire, tin-lead coated copper multistrand wire, and zinc-plated steel rope were used to make electrical marks on pig skin. It is demonstrated that amount of copper, zinc, lead, and iron may serve as statistically reliable indicators for the type of wire, which caused the electrical mark, in spite of the background content of these metals in the skin without injury. Different penetration rates for different metals contained in the wire inflicting an electrical mark were observed.

  10. Competitive adsorption of metals on cabbage waste from multi-metal solutions.

    PubMed

    Hossain, M A; Ngo, H H; Guo, W S; Nghiem, L D; Hai, F I; Vigneswaran, S; Nguyen, T V

    2014-05-01

    This study assessed the adsorption capacity of the agro-waste 'cabbage' as a biosorbent in single, binary, ternary and quaternary sorption systems with Cu(II), Pb(II), Zn(II) and Cd(II) ions. Dried and ground powder of cabbage waste (CW) was used for the sorption of metals ions. Carboxylic, hydroxyl, and amine groups in cabbage waste were found to be the key functional groups for metal sorption. The adsorption isotherms obtained could be well fitted to both the mono- and multi-metal models. In the competitive adsorption systems, cabbage waste adsorbed larger amount of Pb(II) than the other three metals. However, the presence of the competing ions suppressed the sorption of the target metal ions. Except the case of binary system of Cd(II)-Zn(II) and Cd(II)-Cu(II), there was a linear inverse dependency between the sorption capacities and number of different types of competitive metal ions.

  11. Bacterial antibiotic resistance studies using in vitro dynamic models: Population analysis vs. susceptibility testing as endpoints of mutant enrichment.

    PubMed

    Firsov, Alexander A; Strukova, Elena N; Portnoy, Yury A; Shlykova, Darya S; Zinner, Stephen H

    2015-09-01

    Emergence of bacterial antibiotic resistance is usually characterised either by population analysis or susceptibility testing. To compare these endpoints in their ability to demonstrate clear relationships with the ratio of 24-h area under the concentration-time curve (AUC24) to the minimum inhibitory concentration (MIC), enrichment of ciprofloxacin-resistant mutants of four clinical isolates of Pseudomonas aeruginosa was studied in an in vitro dynamic model that simulates mono-exponential pharmacokinetics of ciprofloxacin over a wide range of the AUC24/MIC ratios. Each organism was exposed to twice-daily ciprofloxacin for 3 days. Amplification of resistant mutants was monitored by plating on media with 2×, 4×, 8× and 16× MIC of ciprofloxacin. Population analysis data were expressed by the area under the bacterial mutant concentration-time curve (AUBCM). Changes in P. aeruginosa susceptibility were examined by daily MIC determinations. To account for the different susceptibilities of P. aeruginosa strains, post-exposure MICs (MICfinal) were related to the MICs determined with the starting inoculum (MICinitial). For each organism, AUC24/MIC relationships both with AUBCM and MICfinal/MICinitial were bell-shaped, but the latter were more strain-specific than the former. Using combined data on all four isolates, AUBCM showed a better correlation than MICfinal/MICinitial (r(2)=0.75 vs. r(2)=0.53). The shift of MICfinal/MICinitial relative to AUBCM vs. AUC24/MIC curves resulted in a weak correlation between AUBCM and MICfinal/MICinitial (r(2)=0.41). These data suggest that population analysis is preferable to susceptibility testing in bacterial resistance studies and that these endpoints should not be considered interchangeable.

  12. A Locked Nucleic Acid (LNA)-Based Real-Time PCR Assay for the Rapid Detection of Multiple Bacterial Antibiotic Resistance Genes Directly from Positive Blood Culture

    PubMed Central

    Zhu, Lingxiang; Shen, Dingxia; Zhou, Qiming; Li, Zexia; Fang, Xiangdong; Li, Quan-Zhen

    2015-01-01

    Bacterial strains resistant to various antibiotic drugs are frequently encountered in clinical infections, and the rapid identification of drug-resistant strains is highly essential for clinical treatment. We developed a locked nucleic acid (LNA)-based quantitative real-time PCR (LNA-qPCR) method for the rapid detection of 13 antibiotic resistance genes and successfully used it to distinguish drug-resistant bacterial strains from positive blood culture samples. A sequence-specific primer-probe set was designed, and the specificity of the assays was assessed using 27 ATCC bacterial strains and 77 negative blood culture samples. No cross-reaction was identified among bacterial strains and in negative samples, indicating 100% specificity. The sensitivity of the assays was determined by spiking each bacterial strain into negative blood samples, and the detection limit was 1–10 colony forming units (CFU) per reaction. The LNA-qPCR assays were first applied to 72 clinical bacterial isolates for the identification of known drug resistance genes, and the results were verified by the direct sequencing of PCR products. Finally, the LNA-qPCR assays were used for the detection in 47 positive blood culture samples, 19 of which (40.4%) were positive for antibiotic resistance genes, showing 91.5% consistency with phenotypic susceptibility results. In conclusion, LNA-qPCR is a reliable method for the rapid detection of bacterial antibiotic resistance genes and can be used as a supplement to phenotypic susceptibility testing for the early detection of antimicrobial resistance to allow the selection of appropriate antimicrobial treatment and to prevent the spread of resistant isolates. PMID:25775001

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

    PubMed

    Zhu, Lingxiang; Shen, Dingxia; Zhou, Qiming; Li, Zexia; Fang, Xiangdong; Li, Quan-Zhen

    2015-01-01

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

  14. Bacterial Resistance Studies Using In Vitro Dynamic Models: the Predictive Power of the Mutant Prevention and Minimum Inhibitory Antibiotic Concentrations

    PubMed Central

    Strukova, Elena N.; Shlykova, Darya S.; Portnoy, Yury A.; Kozyreva, Varvara K.; Edelstein, Mikhail V.; Dovzhenko, Svetlana A.; Kobrin, Mikhail B.; Zinner, Stephen H.

    2013-01-01

    In light of the concept of the mutant selection window, i.e., the range between the MIC and the mutant prevention concentration (MPC), MPC-related pharmacokinetic indices should be more predictive of bacterial resistance than the respective MIC-related indices. However, experimental evidence of this hypothesis remains limited and contradictory. To examine the predictive power of the ratios of the area under the curve (AUC24) to the MPC and the MIC, the selection of ciprofloxacin-resistant mutants of four Escherichia coli strains with different MPC/MIC ratios was studied. Each organism was exposed to twice-daily ciprofloxacin for 3 days at AUC24/MIC ratios that provide peak antibiotic concentrations close to the MIC, between the MIC and the MPC, and above the MPC. Resistant E. coli was intensively enriched at AUC24/MPCs from 1 to 10 h (AUC24/MIC from 60 to 360 h) but not at the lower or higher AUC24/MPC and AUC24/MIC ratios. AUC24/MPC and AUC24/MIC relationships of the areas under the time courses of ciprofloxacin-resistant E. coli (AUBCM) were bell-shaped. A Gaussian-like function fits the AUBCM-AUC24/MPC and AUBCM-AUC24/MIC data combined for all organisms (r2 = 0.69 and 0.86, respectively). The predicted anti-mutant AUC24/MPC ratio was 58 ± 35 h, and the respective AUC24/MIC ratio was 1,080 ± 416 h. Although AUC24/MPC was less predictive of strain-independent E. coli resistance than AUC24/MIC, the established anti-mutant AUC24/MPC ratio was closer to values reported for Staphylococcus aureus (60 to 69 h) than the respective AUC24/MIC ratio (1,080 versus 200 to 240 h). This implies that AUC24/MPC might be a better interspecies predictor of bacterial resistance than AUC24/MIC. PMID:23896481

  15. Characterization of hypersensitive resistance to bacterial spot race T3 (Xanthomonas perforans) from tomato accession PI 128216.

    PubMed

    Robbins, Matthew D; Darrigues, Audrey; Sim, Sung-Chur; Masud, Mohammed Abu Taher; Francis, David M

    2009-09-01

    Bacterial spot of tomato is caused by four species of Xanthomonas. The accession PI 128216 (Solanum pimpinellifolium) displays a hypersensitive reaction (HR) to race T3 strains (predominantely Xanthomonas perforans). We developed an inbred backcross (IBC) population (BC(2)S(5), 178 families) derived from PI 128216 and OH88119 (S. lycopersicum) as the susceptible recurrent parent for simultaneous introgression and genetic analysis of the HR response. These IBC families were evaluated in the greenhouse for HR to race T3 strain Xcv761. The IBC population was genotyped with molecular markers distributed throughout the genome in order to identify candidate loci conferring resistance. We treated the IBC population as a hypothesis forming generation to guide validation in subsequent crosses. Nonparametric analysis identified an association between HR and markers clustered on chromosome 11 (P < 0.05 to 0.0001) and chromosome 6 (0.04 > P > 0.002). Further analysis of the IBC population suggested that markers on chromosome 6 and 11 failed to assort independently, a phenomenon known as gametic phase disequilibrium. Therefore, to validate marker-trait linkages, resistant IBC plants were crossed with OH88119 and BC(3)F(2) progeny were evaluated for HR in the greenhouse. In these subsequent populations, the HR response was associated with the chromosome 11 markers (P < 0.0002) but not with the markers on chromosome 6 (P > 0.25). Independent F(2) families were developed by crossing resistant IBC lines to OH8245, OH88119, and OH7530. These populations were genotyped, organized into classes based on chromosome 11 markers, and evaluated for resistance in the field. The PI 128216 locus on chromosome 11 provided resistance that was dependent on gene dosage and genetic background. These results define a single locus, Rx-4, from PI 128216, which provides resistance to bacterial spot race T3, has additive gene action, and is located on chromosome 11.

  16. Insights into the mechanism of inhibition of novel bacterial topoisomerase inhibitors from characterization of resistant mutants of Staphylococcus aureus.

    PubMed

    Lahiri, Sushmita D; Kutschke, Amy; McCormack, Kathy; Alm, Richard A

    2015-09-01

    The type II topoisomerases DNA gyrase and topoisomerase IV are clinically validated bacterial targets that catalyze the modulation of DNA topology that is vital to DNA replication, repair, and decatenation. Increasing resistance to fluoroquinolones, which trap the topoisomerase-DNA complex, has led to significant efforts in the discovery of novel inhibitors of these targets. AZ6142 is a member of the class of novel bacterial topoisomerase inhibitors (NBTIs) that utilizes a distinct mechanism to trap the protein-DNA complex. AZ6142 has very potent activity against Gram-positive organisms, including Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus pyogenes. In this study, we determined the frequencies of resistance to AZ6142 and other representative NBTI compounds in S. aureus and S. pneumoniae. The frequencies of selection of resistant mutants at 4× the MIC were 1.7 × 10(-8) for S. aureus and <5.5 × 10(-10) for S. pneumoniae. To improve our understanding of the NBTI mechanism of inhibition, the resistant S. aureus mutants were characterized and 20 unique substitutions in the topoisomerase subunits were identified. Many of these substitutions were located outside the NBTI binding pocket and impact the susceptibility of AZ6142, resulting in a 4- to 32-fold elevation in the MIC over the wild-type parent strain. Data on cross-resistance with other NBTIs and fluoroquinolones enabled the differentiation of scaffold-specific changes from compound-specific variations. Our results suggest that AZ6142 inhibits both type II topoisomerases in S. aureus but that DNA gyrase is the primary target. Further, the genotype of the resistant mutants suggests that domain conformations and DNA interactions may uniquely impact NBTIs compared to fluoroquinolones.

  17. Synthesis, characterization, PL properties, photocatalytic and antibacterial activities of nano multi-metal oxide NiOṡCeO2ṡZnO

    NASA Astrophysics Data System (ADS)

    Subhan, Md Abdus; Ahmed, Tanzir; Uddin, Nizam; Azad, Abdul Kalam; Begum, Kulsuma

    2015-02-01

    A novel multi-metal nanocomposite, NiOṡCeO2ṡZnO has been prepared by co-precipitation of their carbonates from aqueous solutions of the metal nitrates following calcination and annealing 5 h at 450 °C and 10 h at 950 °C. NiOṡCeO2ṡZnO has been characterized by XRD, SEM, EDS, IR and PL spectra. The crystallite size of the as-synthesized sample varies in the range of 14-23 nm and those of the annealed sample in the range of 17-50 nm. Emissions of NiOṡCeO2ṡZnO have been observed in UV (NBE emission) and visible region at different excitations. Excitation wavelength dependent PL behavior of NiOṡCeO2ṡZnO has been observed in acetone at room temperature. This PL property is in disagreement with Kasha's rule of excitation wavelength dependence of emission spectrum. Photocatalytic as well as anti-bacterial activities were studied.

  18. Synthesis, characterization, PL properties, photocatalytic and antibacterial activities of nano multi-metal oxide NiO⋅CeO2⋅ZnO.

    PubMed

    Subhan, Md Abdus; Ahmed, Tanzir; Uddin, Nizam; Azad, Abdul Kalam; Begum, Kulsuma

    2015-02-05

    A novel multi-metal nanocomposite, NiO⋅CeO2⋅ZnO has been prepared by co-precipitation of their carbonates from aqueous solutions of the metal nitrates following calcination and annealing 5 h at 450°C and 10 h at 950°C. NiO⋅CeO2⋅ZnO has been characterized by XRD, SEM, EDS, IR and PL spectra. The crystallite size of the as-synthesized sample varies in the range of 14-23 nm and those of the annealed sample in the range of 17-50 nm. Emissions of NiO⋅CeO2⋅ZnO have been observed in UV (NBE emission) and visible region at different excitations. Excitation wavelength dependent PL behavior of NiO⋅CeO2⋅ZnO has been observed in acetone at room temperature. This PL property is in disagreement with Kasha's rule of excitation wavelength dependence of emission spectrum. Photocatalytic as well as anti-bacterial activities were studied.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  20. The two-component signal transduction system YvcPQ regulates the bacterial resistance to bacitracin in Bacillus thuringiensis.

    PubMed

    Zhang, Shumeng; Li, Xinfeng; Wang, Xun; Li, Zhou; He, Jin

    2016-10-01

    YvcPQ is one of the two-component signal transduction systems that respond to specific stimuli and enable cells to adjust multiple cellular functions. It consists of a histidine kinase YvcQ and a response regulator YvcP. In this study, through searching the consensus sequence recognized by YvcP, we found four YvcP-binding motifs in the promoter regions of genes yvcR (BMB171_C4100), BMB171_C4385, kapD (BMB171_C4525) and BMB171_C4835 in Bacillus thuringiensis BMB171 which is a representative of Bacillus cereus group, and confirmed that these genes are regulated by YvcP. We compared the sequence of yvcPQ and its downstream genes in genus Bacillus, and found two different kinds of yvc locus, one was the yvcPQ-RS in B. subtilis species and the other was the yvcPQ-R-S1S2 in B. cereus group. Furthermore, we found that YvcP activates the transcription of yvcS1S2 (downstream of yvcR) to promote bacterial resistance to bacitracin and deletion of either yvcPQ operon or yvcS1S2 operon renders the bacterial cells more sensitive to bacitracin. This study enriched our understanding of both the YvcPQ's function and the mechanism of bacterial resistance to bacitracin.

  1. Antimicrobial-Resistant Bacterial Populations and Antimicrobial Resistance Genes Obtained from Environments Impacted by Livestock and Municipal Waste

    PubMed Central

    Durso, Lisa M.; Harhay, Dayna M.; Schmidt, John W.

    2015-01-01

    This study compared the populations of antimicrobial-resistant bacteria and the repertoire of antimicrobial resistance genes in four environments: effluent of three municipal wastewater treatment facilities, three cattle feedlot runoff catchment ponds, three swine waste lagoons, and two “low impact” environments (an urban lake and a relict prairie). Multiple liquid and solid samples were collected from each environment. The prevalences and concentrations of antimicrobial-resistant (AMR) Gram-negative (Escherichia coli and Salmonella enterica) and Gram-positive (enterococci) bacteria were determined from individual samples (n = 174). The prevalences of 84 antimicrobial resistance genes in metagenomic DNA isolated from samples pooled (n = 44) by collection date, location, and sample type were determined. The prevalences and concentrations of AMR E. coli and Salmonella were similar among the livestock and municipal sample sources. The levels of erythromycin-resistant enterococci were significantly higher in liquid samples from cattle catchment ponds and swine waste lagoons than in liquid samples from municipal wastewater treatment facilities, but solid samples from these environments did not differ significantly. Similarly, trimethoprim/sulfamethoxazole-resistant E. coli concentrations were significantly higher in swine liquid than in municipal liquid samples, but there was no difference in solid samples. Multivariate analysis of the distribution of antimicrobial resistance genes using principal coordinate analysis showed distinct clustering of samples with livestock (cattle and swine), low impact environment and municipal samples forming three separate clusters. The numbers of class A beta-lactamase, class C beta-lactamase, and fluoroquinolone resistance genes detected were significantly higher (P < 0.05) in municipal samples than in cattle runoff or swine lagoon samples. In conclusion, we report that AMR is a very widespread phenomenon and that similar

  2. The population genetics of drug resistance evolution in natural populations of viral, bacterial and eukaryotic pathogens

    PubMed Central

    WILSON, BENJAMIN A.; GARUD, NANDITA R.; FEDER, ALISON F.; ASSAF, ZOE J.; PENNINGS, PLEUNI S.

    2016-01-01

    Drug resistance is a costly consequence of pathogen evolution and a major concern in public health. In this review, we show how population genetics can be used to study the evolution of drug resistance and also how drug resistance evolution is informative as an evolutionary model system. We highlight five examples from diverse organisms with particular focus on: (i) identifying drug resistance loci in the malaria parasite Plasmodium falciparum using the genomic signatures of selective sweeps, (ii) determining the role of epistasis in drug resistance evolution in influenza, (iii) quantifying the role of standing genetic variation in the evolution of drug resistance in HIV, (iv) using drug resistance mutations to study clonal interference dynamics in tuberculosis and (v) analysing the population structure of the core and accessory genome of Staphylococcus aureus to understand the spread of methicillin resistance. Throughout this review, we discuss the uses of sequence data and population genetic theory in studying the evolution of drug resistance. PMID:26578204

  3. The population genetics of drug resistance evolution in natural populations of viral, bacterial and eukaryotic pathogens.

    PubMed

    Wilson, Benjamin A; Garud, Nandita R; Feder, Alison F; Assaf, Zoe J; Pennings, Pleuni S

    2016-01-01

    Drug resistance is a costly consequence of pathogen evolution and a major concern in public health. In this review, we show how population genetics can be used to study the evolution of drug resistance and also how drug resistance evolution is informative as an evolutionary model system. We highlight five examples from diverse organisms with particular focus on: (i) identifying drug resistance loci in the malaria parasite Plasmodium falciparum using the genomic signatures of selective sweeps, (ii) determining the role of epistasis in drug resistance evolution in influenza, (iii) quantifying the role of standing genetic variation in the evolution of drug resistance in HIV, (iv) using drug resistance mutations to study clonal interference dynamics in tuberculosis and (v) analysing the population structure of the core and accessory genome of Staphylococcus aureus to understand the spread of methicillin resistance. Throughout this review, we discuss the uses of sequence data and population genetic theory in studying the evolution of drug resistance.

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

    PubMed Central

    Devarajan, Naresh; Laffite, Amandine; Mulaji, Crispin Kyela; Otamonga, Jean-Paul; Mpiana, Pius Tshimankinda; Mubedi, Josué Ilunga; Prabakar, Kandasamy; Ibelings, Bastiaan Willem; Poté, John

    2016-01-01

    The occurrence of emerging biological contaminants including antibiotic resistance genes (ARGs) and Faecal Indicator Bacteria (FIB) is still little investigated in developing countries under tropical conditions. In this study, the total bacterial load, the abundance of FIB (E. coli and Enterococcus spp. (ENT)), Pseudomonas spp. and ARGs (blaTEM, blaCTX-M, blaSHV, blaNDM and aadA) were quantified using quantitative PCR in the total DNA extracted from the sediments recovered from hospital outlet pipes (HOP) and the Cauvery River Basin (CRB), Tiruchirappalli, Tamil Nadu, India. The abundance of bacterial marker genes were 120, 104 and 89 fold higher for the E. coli, Enterococcus spp. and Pseudomonas spp., respectively at HOP when compared with CRB. The ARGs aadA and blaTEM were most frequently detected in higher concentration than other ARGs at all the sampling sites. The ARGs blaSHV and blaNDM were identified in CRB sediments contaminated by hospital and urban wastewaters. The ARGs abundance strongly correlated (r ≥ 0.36, p < 0.05, n = 45) with total bacterial load and E. coli in the sediments, indicating a common origin and extant source of contamination. Tropical aquatic ecosystems receiving wastewaters can act as reservoir of ARGs, which could potentially be transferred to susceptible bacterial pathogens at these sites. PMID:26910062

  5. Attempt to develop live attenuated bacterial vaccines by selecting resistance to gossypol, proflavine hemisulfate, novobiocin, or ciprofloxacin.

    PubMed

    Pridgeon, Julia W; Klesius, Phillip H; Yildirim-Aksoy, Mediha

    2013-04-26

    In an attempt to develop attenuated bacteria as potential live vaccines, four chemicals (gossypol, proflavine hemisulfate, novobiocin, and ciprofloxacin) were used to modify the following four genera of bacteria through chemical-resistance strategy: (1) Aeromonas hydrophila (9 isolates); (2) Edwardsiella tarda (9 isolates); (3) Streptococcus iniae (9 isolates); and (4) S. agalactiae (11 isolates). All bacteria used in this study were able to develop high resistance to gossypol. However, only some bacteria were able to develop resistance to proflavine hemisulfate, novobiocin, or ciprofloxacin. When the virulence of resistant bacteria was tested in tilapia or catfish, none of the gossypol-resistant isolate was attenuated, whereas majority of the proflavine hemisulfate-resistant isolates were attenuated. However, all proflavine hemisulfate-attenuated bacteria failed to provide significant protection to fish. Eight novobiocin- or ciprofloxacin-resistant Gram-positive bacteria (S. agalactiae and S. inaie) were found to be attenuated. However, none of them offered protection higher than 70%. Of seven attenuated novobiocin- or ciprofloxacin-resistant Gram-negative isolates (A. hydrophila and E. tarda), only one (novobiocin-resistant E. tarda 30305) was found to safe and highly efficacious. When E. tarda 30305-novo vaccinated Nile tilapia were challenged by its virulent E. tarda 30305, relative percent of survival of vaccinated fish at 14- and 28-days post vaccination (dpv) was 100% and 92%, respectively. Similarly, E. tarda 30305-novo offered 100% protection to channel catfish against challenges with virulent parent isolate E. tarda 30305 at both 14- and 28-dpv. Our results suggest that the development of live attenuated bacterial vaccines that are safe and efficacious is challenging, although it is feasible.

  6. Triclosan Resistance in a Bacterial Fish Pathogen, Aeromonas salmonicida subsp. salmonicida, is Mediated by an Enoyl Reductase, FabV.

    PubMed

    Khan, Raees; Lee, Myung Hwan; Joo, Hae-Jin; Jung, Yong-Hoon; Ahmad, Shabir; Choi, Jin-Hee; Lee, Seon-Woo

    2015-04-01

    Triclosan, the widely used biocide, specifically targets enoyl-acyl carrier protein reductase (ENR) in the bacterial fatty acid synthesis system. Although the fish pathogen Aeromonas salmonicida subsp. salmonicida exhibits triclosan resistance, the nature of this resistance has not been elucidated. Here, we aimed to characterize the triclosan resistance of A. salmonicida subsp. salmonicida causing furunculosis. The fosmid library of triclosan-resistant A. salmonicida subsp. salmonicida was constructed to select a fosmid clone showing triclosan resistance. With the fosmid clone showing triclosan resistance, a subsequent secondary library search resulted in the selection of subclone pTSR-1. DNA sequence analysis of pTSR-1 revealed the presence of a chromosomal-borne fabV-encoding ENR homolog. The ENR of A. salmonicida (FabVas) exhibited significant homology with previously known FabV, including the catalytic domain YX(8)K. fabVas introduction into E. coli dramatically increased its resistance to triclosan. Heterologous expression of FabVas might functionally replace the triclosan-sensitive FabI in vivo to confer E. coli with triclosan resistance. A genome-wide search for fabVas homologs revealed the presence of an additional fabV gene (fabVas2) paralog in A. salmonicida strains and the fabVas orthologs from other gram-negative fish pathogens. Both of the potential FabV ENRs expressed similarly with or without triclosan supplement. This is the first report about the presence of two potential FabV ENRs in a single pathogenic bacterium. Our result suggests that triclosan-resistant ENRs are widely distributed in various bacteria in nature, and the wide use of this biocide can spread these triclosan-tolerant ENRs among fish pathogens and other pathogenic bacteria.

  7. Antimicrobial-resistant bacterial populations and antimicrobial resistance genes obtained from environments impacted by livestock and municipal waste

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study compared the populations of antimicrobial-resistant bacteria and the repertoire of antimicrobial resistance genes in four environments: effluent of three municipal waste water treatment facilities, three cattle feedlot runoff catchment ponds, three swine waste lagoons, and two "low impact...

  8. Characterization of antibiotic resistant and enzyme producing bacterial strains isolated from the Arabian Sea.

    PubMed

    Tallur, Preeti N; Sajjan, Dayanand B; Mulla, Sikandar I; Talwar, Manjunatha P; Pragasam, A; Nayak, Vinayak M; Ninnekar, Harichandra Z; Bhat, Shivanand S

    2016-06-01

    Marine bacteria are known to produce many bioactive molecules and extracellular enzymes of commercial importance. We have investigated the bacterial diversity of the coastal area of Karwar, Karnataka State, India. Among these bacterial isolates, five bacterial strains were selected and identified by their morphological, biochemical characteristics and phylogenetic analysis based on 16S rRNA gene sequences. The identified bacterial isolates, Bacillus toyonensis PNTB1, Lysinibacillus sphaericus PTB, Vibrio vulnificus PMD, Shewanella MPTDBS, and Pseudomonas chlororaphis PNTB were characterized for their tolerance to salt and antibiotics. Vibrio vulnificus PMD showed maximum tolerance at higher concentration of salt than other bacteria. These bacterial strains were screened for the production of extracellular enzymes such as lipase, cellulase, pectinase, tannase, chitinase, and L-glutaminase. Vibrio vulnificus showed maximum production of L-glutaminase enzyme. Bacillus toyonensis PNTB1 shows lipase, CM-cellulase and chitinase activities. These isolated bacterial cultures were also utilized most of the aromatic compounds at 7 mM. These findings indicate the organisms present in this zone may have more potential applications in bioremediation, agricultural, industrial, and therapeutics.

  9. High-throughput genomic sequencing of cassava bacterial blight strains identifies conserved effectors to target for durable resistance.

    PubMed

    Bart, Rebecca; Cohn, Megan; Kassen, Andrew; McCallum, Emily J; Shybut, Mikel; Petriello, Annalise; Krasileva, Ksenia; Dahlbeck, Douglas; Medina, Cesar; Alicai, Titus; Kumar, Lava; Moreira, Leandro M; Rodrigues Neto, Júlio; Verdier, Valerie; Santana, María Angélica; Kositcharoenkul, Nuttima; Vanderschuren, Hervé; Gruissem, Wilhelm; Bernal, Adriana; Staskawicz, Brian J

    2012-07-10

    Cassava bacterial blight (CBB), incited by Xanthomonas axonopodis pv. manihotis (Xam), is the most important bacterial disease of cassava, a staple food source for millions of people in developing countries. Here we present a widely applicable strategy for elucidating the virulence components of a pathogen population. We report Illumina-based draft genomes for 65 Xam strains and deduce the phylogenetic relatedness of Xam across the areas where cassava is grown. Using an extensive database of effector proteins from animal and plant pathogens, we identify the effector repertoire for each sequenced strain and use a comparative sequence analysis to deduce the least polymorphic of the conserved effectors. These highly conserved effectors have been maintained over 11 countries, three continents, and 70 y of evolution and as such represent ideal targets for developing resistance strategies.

  10. In vitro activities of a novel nanoemulsion against Burkholderia and other multidrug-resistant cystic fibrosis-associated bacterial species.

    PubMed

    LiPuma, John J; Rathinavelu, Sivaprakash; Foster, Bridget K; Keoleian, Jordan C; Makidon, Paul E; Kalikin, Linda M; Baker, James R

    2009-01-01

    Respiratory tract infection, most often involving opportunistic bacterial species with broad-spectrum antibiotic resistance, is the primary cause of death in persons with cystic fibrosis (CF). Species within the Burkholderia cepacia complex are especially problematic in this patient population. We investigated a novel surfactant-stabilized oil-in-water nanoemulsion (NB-401) for activity against 150 bacterial isolates recovered primarily from CF respiratory tract specimens. These specimens included 75 Burkholderia isolates and 75 isolates belonging to other CF-relevant species including Pseudomonas, Achromobacter, Pandoraea, Ralstonia, Stenotrophomonas, and Acinetobacter. Nearly one-third of the isolates were multidrug resistant, and 20 (13%) were panresistant based on standard antibiotic testing. All isolates belonging to the same species were genotyped to ensure that each isolate was a distinct strain. The MIC(90) of NB-401 was 125 microg/ml. We found no decrease in activity against multidrug-resistant or panresistant strains. MBC testing showed no evidence of tolerance to NB-401. We investigated the activity of NB-401 against a subset of strains grown as a biofilm and against planktonic strains in the presence of CF sputum. Although the activity of NB-401 was decreased under both conditions, the nanoemulsion remained bactericidal for all strains tested. These results support NB-401's potential role as a novel antimicrobial agent for the treatment of infection due to CF-related opportunistic pathogens.

  11. Whole-Genome Sequencing of Invasion-Resistant Cells Identifies Laminin α2 as a Host Factor for Bacterial Invasion

    PubMed Central

    van Wijk, Xander M.; Döhrmann, Simon; Hallström, Björn M.; Li, Shangzhong; Voldborg, Bjørn G.; Meng, Brandon X.; McKee, Karen K.; van Kuppevelt, Toin H.; Yurchenco, Peter D.; Palsson, Bernhard O.; Lewis, Nathan E.; Nizet, Victor

    2017-01-01

    ABSTRACT To understand the role of glycosaminoglycans in bacterial cellular invasion, xylosyltransferase-deficient mutants of Chinese hamster ovary (CHO) cells were created using clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated gene 9 (CRISPR-cas9) gene targeting. When these mutants were compared to the pgsA745 cell line, a CHO xylosyltransferase mutant generated previously using chemical mutagenesis, an unexpected result was obtained. Bacterial invasion of pgsA745 cells by group B Streptococcus (GBS), group A Streptococcus, and Staphylococcus aureus was markedly reduced compared to the invasion of wild-type cells, but newly generated CRISPR-cas9 mutants were only resistant to GBS. Invasion of pgsA745 cells was not restored by transfection with xylosyltransferase, suggesting that an additional mutation conferring panresistance to multiple bacteria was present in pgsA745 cells. Whole-genome sequencing and transcriptome sequencing (RNA-Seq) uncovered a deletion in the gene encoding the laminin subunit α2 (Lama2) that eliminated much of domain L4a. Silencing of the long Lama2 isoform in wild-type cells strongly reduced bacterial invasion, whereas transfection with human LAMA2 cDNA significantly enhanced invasion in pgsA745 cells. The addition of exogenous laminin-α2β1γ1/laminin-α2β2γ1 strongly increased bacterial invasion in CHO cells, as well as in human alveolar basal epithelial and human brain microvascular endothelial cells. Thus, the L4a domain in laminin α2 is important for cellular invasion by a number of bacterial pathogens. PMID:28074024

  12. Interactions Between QTL SAP6 and SU91 on Resistance to Common Bacterial Blight in Red Kidney Bean and Pinto Bean Populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resistance to common bacterial blight in common bean is a complex trait that is quantitatively inherited. We examined the interaction between two independent QTL, SAP6 and SU91, which condition resistance to CBB.The QTL were studied in a pinto bean F2 population a cross between Othello (sap6 sap6 //...

  13. Identification of single nucleotide polymorphism markers associated with bacterial cold water disease resistance and spleen size in rainbow trout.

    PubMed

    Liu, Sixin; Vallejo, Roger L; Palti, Yniv; Gao, Guangtu; Marancik, David P; Hernandez, Alvaro G; Wiens, Gregory D

    2015-01-01

    Bacterial cold water disease (BCWD) is one of the frequent causes of elevated mortality in salmonid aquaculture. Previously, we identified and validated microsatellites on chromosome Omy19 associated with QTL (quantitative trait loci) for BCWD resistance and spleen size in rainbow trout. Recently, SNPs (single nucleotide polymorphism) have become the markers of choice for genetic analyses in rainbow trout as they are highly abundant, cost-effective and are amenable for high throughput genotyping. The objective of this study was to identify SNP markers associated with BCWD resistance and spleen size using both genome-wide association studies (GWAS) and linkage-based QTL mapping approaches. A total of 298 offspring from the two half-sib families used in our previous study to validate the significant BCWD QTL on chromosome Omy19 were genotyped with RAD-seq (restriction-site-associated DNA sequencing), and 7,849 informative SNPs were identified. Based on GWAS, 18 SNPs associated with BCWD resistance and 20 SNPs associated with spleen size were identified. Linkage-based QTL mapping revealed three significant QTL for BCWD resistance. In addition to the previously validated dam-derived QTL on chromosome Omy19, two significant BCWD QTL derived from the sires were identified on chromosomes Omy8 and Omy25, respectively. A sire-derived significant QTL for spleen size on chromosome Omy2 was detected. The SNP markers reported in this study will facilitate fine mapping to identify positional candidate genes for BCWD resistance in rainbow trout.

  14. Methicillin-resistant Staphylococcus aureus Bacterial Nitric-oxide Synthase Affects Antibiotic Sensitivity and Skin Abscess Development*

    PubMed Central

    van Sorge, Nina M.; Beasley, Federico C.; Gusarov, Ivan; Gonzalez, David J.; von Köckritz-Blickwede, Maren; Anik, Sabina; Borkowski, Andrew W.; Dorrestein, Pieter C.; Nudler, Evgeny; Nizet, Victor

    2013-01-01

    Staphylococcus aureus infections present an enormous global health concern complicated by an alarming increase in antibiotic resistance. S. aureus is among the few bacterial species that express nitric-oxide synthase (bNOS) and thus can catalyze NO production from l-arginine. Here we generate an isogenic bNOS-deficient mutant in the epidemic community-acquired methicillin-resistant S. aureus (MRSA) USA300 clone to study its contribution to virulence and antibiotic susceptibility. Loss of bNOS increased MRSA susceptibility to reactive oxygen species and host cathelicidin antimicrobial peptides, which correlated with increased MRSA killing by human neutrophils and within neutrophil extracellular traps. bNOS also promoted resistance to the pharmaceutical antibiotics that act on the cell envelope such as vancomycin and daptomycin. Surprisingly, bNOS-deficient strains gained resistance to aminoglycosides, suggesting that the role of bNOS in antibiotic susceptibility is more complex than previously observed in Bacillus species. Finally, the MRSA bNOS mutant showed reduced virulence with decreased survival and smaller abscess generation in a mouse subcutaneous infection model. Together, these data indicate that bNOS contributes to MRSA innate immune and antibiotic resistance phenotypes. Future development of specific bNOS inhibitors could be an attractive option to simultaneously reduce MRSA pathology and enhance its susceptibility to commonly used antibiotics. PMID:23322784

  15. A mutation within the leucine-rich repeat domain of the Arabidopsis disease resistance gene RPS5 partially suppresses multiple bacterial and downy mildew resistance genes.

    PubMed Central

    Warren, R F; Henk, A; Mowery, P; Holub, E; Innes, R W

    1998-01-01

    Recognition of pathogens by plants is mediated by several distinct families of functionally variable but structurally related disease resistance (R) genes. The largest family is defined by the presence of a putative nucleotide binding domain and 12 to 21 leucine-rich repeats (LRRs). The function of these LRRs has not been defined, but they are speculated to bind pathogen-derived ligands. We have isolated a mutation in the Arabidopsis RPS5 gene that indicates that the LRR region may interact with other plant proteins. The rps5-1 mutation causes a glutamate-to-lysine substitution in the third LRR and partially compromises the function of several R genes that confer bacterial and downy mildew resistance. The third LRR is relatively well conserved, and we speculate that it may interact with a signal transduction component shared by multiple R gene pathways. PMID:9724691

  16. Resistance and resilience of removal efficiency and bacterial community structure of gas biofilters exposed to repeated shock loads.

    PubMed

    Cabrol, Léa; Malhautier, Luc; Poly, Franck; Roux, Xavier Le; Lepeuple, Anne-Sophie; Fanlo, Jean-Louis

    2012-11-01

    Since full-scale biofilters are often operated under fluctuating conditions, it is critical to understand their response to transient states. Four pilot-scale biofilters treating a composting gas mixture and undergoing repeated substrate pulses of increasing intensity were studied. A systematic approach was proposed to quantify the resistance and resilience capacity of their removal efficiency, which enabled to distinguish between recalcitrant (ammonia, DMDS, ketones) and easily degradable (esters and aldehyde) compounds. The threshold of disturbing shock intensity and the influence of disturbance history depended on the contaminant considered. The spatial and temporal distribution of the bacterial community structure in response to the perturbation regime was analysed by Denaturing Gradient Gel Electrophoresis (DGGE). Even if the substrate-pulses acted as a driving force for some community characteristics (community stratification), the structure-function relationships were trickier to evidence: the distributions of resistance and composition were only partially coupled, with contradictory results depending on the contaminant considered.

  17. The animal food supplement sepiolite promotes a direct horizontal transfer of antibiotic resistance plasmids between bacterial species.

    PubMed

    Rodríguez-Beltrán, Jerónimo; Rodríguez-Rojas, Alexandro; Yubero, Elva; Blázquez, Jesús

    2013-06-01

    Animal fodder is routinely complemented with antibiotics together with other food supplements to improve growth. For instance, sepiolite is currently used as a dietary coadjuvant in animal feed, as it increases animal growth parameters and improves meat and derived final product quality. This type of food additive has so far been considered innocuous for the development and spread of antibiotic resistance. In this study, we demonstrate that sepiolite promotes the direct horizontal transfer of antibiotic resistance plasmids between bacterial species. The conditions needed for plasmid transfer (sepiolite and friction forces) occur in the digestive tracts of farm animals, which routinely receive sepiolite as a food additive. Furthermore, this effect may be aggravated by the use of antibiotics supplied as growth promoters.

  18. Selective modification of the 3''-amino group of kanamycin prevents significant loss of activity in resistant bacterial strains.

    PubMed

    Santana, Andrés G; Zárate, Sandra G; Asensio, Juan Luis; Revuelta, Julia; Bastida, Agatha

    2016-01-14

    Aminoglycosides are highly potent, wide-spectrum bactericidals. N-1 modification of aminoglycosides has thus far been the best approach to regain bactericidal efficiency of this class of antibiotics against resistant bacterial strains. In the present study we have evaluated the effect that both, the number of modifications and their distribution on the aminoglycoside amino groups (N-1, N-3, N-6' and N-3''), have on the antibiotic activity. The modification of N-3'' in the antibiotic kanamycin A is the key towards the design of new aminoglycoside antibiotics. This derivative maintains the antibiotic activity against aminoglycoside acetyl-transferase- and nucleotidyl-transferase-expressing strains, which are two of the most prevalent modifying enzymes found in aminoglycoside resistant bacteria.

  19. Resistance of different stocks and transferrin genotypes of coho salmon, Oncorhynchus kisutch, and steelhead trout, Salmo gairdneri, to bacterial kidney disease and vibriosis

    USGS Publications Warehouse

    Winter , Gary W.; Schreck, Carl B.; McIntyre, John D.

    1979-01-01

    Juvenile coho salmon and steelhead trout ofdifferentstocks and three transferrin genotypes(AA, AC, and CCl, all reared in identical or similar environments, were experimentally infected with Corynebacterium sp., the causative agent ofbacterial kidney disease, or with Vibrio anguillarum, the causative agent of vibriosis. Mortality due to the pathogens was compared among stocks within a species and among transferrin genotypes within a stock to determine whetherthere was a geneticbasis for resistance to disease. Differences in resistance to bacterial kidney disease among coho salmon stocks had a genetic basis. Stock susceptibility to vibriosis was strongly influenced by environmental factors. Coho salmon orsteelhead trout of one stock may be resistant to one disease but susceptible to another. The importance of transferrin genotype of coho salmon in resistance to bacterial kidney disease was stock specific; in stocks that showed differential resistance of genotypes, the AA was the most susceptible. No differencesin resistance to vibriosis were observed among transferrin genotypes.

  20. Reengineering Antibiotics to Combat Bacterial Resistance: Click Chemistry [1,2,3]-Triazole Vancomycin Dimers with Potent Activity against MRSA and VRE.

    PubMed

    Silverman, Steven M; Moses, John E; Sharpless, K Barry

    2017-01-01

    Vancomycin has long been considered a drug of last resort. Its efficiency in treating multiple drug-resistant bacterial infections, particularly methicillin-resistant Staphylococcus aureus (MRSA), has had a profound effect on the treatment of life-threatening infections. However, the emergence of resistance to vancomycin is a cause for significant worldwide concern, prompting the urgent development of new effective treatments for antibiotic resistant bacterial infections. Harnessing the benefits of multivalency and cooperativity against vancomycin-resistant strains, we report a Click Chemistry approach towards reengineered vancomycin derivatives and the synthesis of a number of dimers with increased potency against MRSA and vancomycin resistant Enterococci (VRE; VanB). These semi-synthetic dimeric ligands were linked together with great efficiency using the powerful CuAAC reaction, demonstrating high levels of selectivity and purity.

  1. Bacterial Colonization and Antibiotic Resistance in a Prospective Cohort of Newborn Infants During the First Year of Life

    PubMed Central

    Stange, Kurt C.; Jacobs, Michael R.; Weiss, Judith K.; Bajaksouzian, Saralee; Bonomo, Robert A.

    2016-01-01

    Background. Infants are virtually sterile at birth and frequently use antibiotics; our objective was to (1) characterize the longitudinal colonization with bacterial pathogens and associated antibiotic resistance in a cohort of community-dwelling infants in Northeast Ohio and (2) describe longitudinal concurrent antibiotic and daycare exposures. Methods. For 35 newborns, nasopharyngeal swabs were cultured for Streptococcus pneumoniae, anterior nasal for Staphylococcus aureus, and perirectal for extended-spectrum beta-lactamase (ESBL)-producing Gram-negative enteric bacteria, at 3-month intervals for 12 months. Infant and household antibiotics and daycare exposure were assessed longitudinally. Results. Thirteen infants received perinatal or nursery antibiotics. By 3 months, at least 22 were colonized with Gram-negative bacteria; 2 with S pneumoniae (type 19A, resistant; 15C, susceptible), 5 with methicillin-susceptible S aureus. By 12 months, at least 22 of 35 infants received antibiotics, 20 had household members with antibiotics, and 12 attended daycare; 7 more had household members with daycare exposure. The ESBL-producing organisms were not identified. At least 10 infants were colonized at some time with an antibiotic-resistant organism, 3 more with pathogens displaying intermediate resistance. Pathogen colonization and resistance were intermittent and inconsistent. Conclusions. In a community-based cohort followed from birth, early antibiotic and daycare exposures are common, especially considering perinatal maternal exposures. Colonization patterns of Gram-negative bacteria, S pneumoniae, S aureus, and resistant pneumococci are strikingly dynamic. Further research can identify key areas for potential interventions to maximize clinical antibiotic outcomes while minimizing future resistance. PMID:27957505

  2. Bacterial self-resistance to the natural proteasome inhibitor salinosporamide A

    PubMed Central

    Kale, Andrew J.; McGlinchey, Ryan P.; Lechner, Anna; Moore, Bradley S.

    2011-01-01

    Proteasome inhibitors have recently emerged as a therapeutic strategy in cancer chemotherapy but susceptibility to drug resistance limits their efficacy. The marine actinobacterium Salinispora tropica produces salinosporamide A (NPI-0052, marizomib), a potent proteasome inhibitor and promising clinical agent in the treatment of multiple myeloma. Actinobacteria also possess 20S proteasome machinery, raising the question of self-resistance. We identified a redundant proteasome β-subunit, SalI, encoded within the salinosporamide biosynthetic gene cluster and biochemically characterized the SalI proteasome complex. The SalI β-subunit has an altered substrate specificity profile, 30-fold resistance to salinosporamide A, and cross-resistance to the FDA-approved proteasome inhibitor bortezomib. An A49V mutation in SalI correlates to clinical bortezomib resistance from a human proteasome β 5-subunit A49T mutation, suggesting that intrinsic resistance to natural proteasome inhibitors may predict clinical outcomes. PMID:21882868

  3. Quantitative PCR Monitoring of Antibiotic Resistance Genes and Bacterial Pathogens in Three European Artificial Groundwater Recharge Systems▿ †

    PubMed Central

    Böckelmann, Uta; Dörries, Hans-Henno; Ayuso-Gabella, M. Neus; Salgot de Marçay, Miquel; Tandoi, Valter; Levantesi, Caterina; Masciopinto, Costantino; Van Houtte, Emmanuel; Szewzyk, Ulrich; Wintgens, Thomas; Grohmann, Elisabeth

    2009-01-01

    Aquifer recharge presents advantages for integrated water management in the anthropic cycle, namely, advanced treatment of reclaimed water and additional dilution of pollutants due to mixing with natural groundwater. Nevertheless, this practice represents a health and environmental hazard because of the presence of pathogenic microorganisms and chemical contaminants. To assess the quality of water extracted from recharged aquifers, the groundwater recharge systems in Torreele, Belgium, Sabadell, Spain, and Nardò, Italy, were investigated for fecal-contamination indicators, bacterial pathogens, and antibiotic resistance genes over the period of 1 year. Real-time quantitative PCR assays for Helicobacter pylori, Yersinia enterocolitica, and Mycobacterium avium subsp. paratuberculosis, human pathogens with long-time survival capacity in water, and for the resistance genes ermB, mecA, blaSHV-5, ampC, tetO, and vanA were adapted or developed for water samples differing in pollutant content. The resistance genes and pathogen concentrations were determined at five or six sampling points for each recharge system. In drinking and irrigation water, none of the pathogens were detected. tetO and ermB were found frequently in reclaimed water from Sabadell and Nardò. mecA was detected only once in reclaimed water from Sabadell. The three aquifer recharge systems demonstrated different capacities for removal of fecal contaminators and antibiotic resistance genes. Ultrafiltration and reverse osmosis in the Torreele plant proved to be very efficient barriers for the elimination of both contaminant types, whereas aquifer passage followed by UV treatment and chlorination at Sabadell and the fractured and permeable aquifer at Nardò posed only partial barriers for bacterial contaminants. PMID:19011075

  4. Current epidemiology and antimicrobial resistance data for bacterial bloodstream infections in patients with hematologic malignancies: an Italian multicentre prospective survey.

    PubMed

    Trecarichi, E M; Pagano, L; Candoni, A; Pastore, D; Cattaneo, C; Fanci, R; Nosari, A; Caira, M; Spadea, A; Busca, A; Vianelli, N; Tumbarello, M

    2015-04-01

    A prospective cohort study was conducted in nine hematology wards at tertiary care centres or at university hospitals located throughout Italy from January 2009 to December 2012. All of the cases of bacterial bloodstream infection (BBSI) occurring in adult patients with hematologic malignancies were included. A total of 668 bacterial isolates were recovered in 575 BBSI episodes. Overall, the susceptibility rates of Gram-negative bacteria were 59.1% to ceftazidime, 20.1% to ciprofloxacin, 79.1% to meropenem, 85.2% to amikacin, 69.2% to gentamicin and 69.8% to piperacillin/tazobactam. Resistance to third-generation cephalosporins was found in 98/265 (36.9%) of Enterobacteriaceae isolates. Among Klebsiella pneumoniae strains, 15/43 (34.9%) were resistant to carbapenems. Of 66 Pseudomonas aeruginosa isolates, 46 (69.7%) were multidrug resistant. Overall, the susceptibility rates of Gram-positive bacteria were 97.4% to vancomycin and 94.2% to teicoplanin. Among the monomicrobial cases of BBSI, the 21-day mortality rate was significantly higher for those caused by Gram-negative bacteria compared to those caused by Gram-positive bacteria (47/278, 16.9% vs. 12/212, 5.6%; p < 0.001). Among Gram-negative bacteria, the mortality rate was significantly higher for BBSI caused by K. pneumoniae, P. aeruginosa, and Acinetobacter baumannii. Our results confirm the recently reported shift of prevalence from Gram-positive to Gram-negative bacteria as causative agents of BBSIs among patients with hematologic malignancies and highlight a worrisome increasing frequency in antimicrobial resistance among Gram-negative bacteria.

  5. Responses of plasmid-mediated quinolone resistance genes and bacterial taxa to (fluoro)quinolones-containing manure in arable soil.

    PubMed

    Xiong, Wenguang; Sun, Yongxue; Ding, Xueyao; Zhang, Yiming; Zhong, Xiaoxia; Liang, Wenfei; Zeng, Zhenling

    2015-01-01

    The aim of the present study was to investigate the fate of plasmid-mediated quinolone resistance (PMQR) genes and the disturbance of soil bacterial communities posed by (fluoro)quinolones (FQNs)-containing manure in arable soil. Representative FQNs (enrofloxacin (ENR), ciprofloxacin (CIP) and norfloxacin (NOR)), PMQR genes (qepA, oqxA, oqxB, aac(6')-Ib-cr and qnrS) and bacterial communities in untreated soil, +manure and +manure+FQNs groups were analyzed using culture independent methods. The significantly higher abundance of oqxA, oqxB and aac(6')-Ib-cr, and significantly higher abundance of qnrS in +manure group than those in untreated soil disappeared at day 30 and day 60, respectively. All PMQR genes (oqxA, oqxB, aac(6')-Ib-cr and qnrS) dissipated 1.5-1.7 times faster in +manure group than those in +manure+FQNs group. The disturbance of soil bacterial communities posed by FQNs-containing manure was also found. The results indicated that significant effects of PMQR genes (oqxA, oqxB, aac(6')-Ib and qnrS) on arable soils introduced by manure disappeared 2 month after manure application. FQNs introduced by manure slowed down the dissipation of PMQR genes. The presence of high FQNs provided a selective advantage for species affiliated to the phylum including Acidobacteria, Verrucomicrobia and Planctomycetes while suppressing Proteobacteria and Actinobacteria.

  6. The role of silicon in enhancing resistance to bacterial blight of hydroponic- and soil-cultured rice.

    PubMed

    Song, Alin; Xue, Gaofeng; Cui, Peiyuan; Fan, Fenliang; Liu, Hongfang; Yin, Chang; Sun, Wanchun; Liang, Yongchao

    2016-04-19

    Here we report for the first time that bacterial blight of rice can be alleviated by silicon (Si) added. In both inoculated and uninoculated plants, shoot dry weight was significantly higher in the +Si plants than in the -Si plants. A soil-cultured trial showed that disease severity was 24.3% lower in the Si-amended plants than in the non-Si-amended plants. Plants that were switched from -Si to +Si nutrient solution and simultaneously inoculated with Xoo also exhibited the same high resistance to bacterial blight as the plants that were treated continuously with Si, with control efficiencies of 52.8 and 62.9%, respectively. Moreover, total concentrations of soluble phenolics and lignin in rice leaves were significantly higher in the +Si plants than in the -Si plants. Polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities in rice leaves were observed to be higher in the +Si plants than in the -Si plants. The expression levels of Os03g0109600, Prla, Rcht2 and Lox2osPil, were also higher in +Si plants than in -Si plants post-inoculation during the experimental time. Addition of Si resulted in increased Pal transcription, and inhibited CatA and Os03g0126000 expression in the earlier and later stages of bacterial inoculation, respectively.

  7. Production of putrescine-capped stable silver nanoparticle: its characterization and antibacterial activity against multidrug-resistant bacterial strains

    NASA Astrophysics Data System (ADS)

    Saha, Saswati; Gupta, Bhaskar; Gupta, Kamala; Chaudhuri, Mahua Ghosh

    2016-11-01

    Integration of biology with nanotechnology is now becoming attention-grabbing area of research. The antimicrobial potency of silver has been eminent from antiquity. Due to the recent desire for the enhancement of antibacterial efficacy of silver, various synthesis methods of silver in their nano dimensions are being practiced using a range of capping material. The present work highlights a facile biomimetic approach for production of silver nanoparticle being capped and stabilized by putrescine, possessing a diameter of 10-25 ± 1.5 nm. The synthesized nanoparticles have been analyzed spectrally and analytically. Morphological studies are carried out by high-resolution transmission electron microscopy and crystallinity by selected area electron diffraction patterns. Moreover, the elemental composition of the capped nanoparticles was confirmed by energy-dispersive X-ray spectroscopy analysis. A comparative study (zone of inhibition and minimum inhibitory concentration) regarding the interactions and antibacterial potentiality of the capped silver nanoparticles with respect to the bare ones reveal the efficiency of the capped one over the bare one. The bacterial kinetic study was executed to monitor the interference of nanoparticles with bacterial growth rate. The results also highlight the efficacy of putrescine-capped silver nanoparticles as effective growth inhibitors against multi-drug resistant human pathogenic bacterial strains, which may, thus, potentially be applicable as an effective antibacterial control system to fight diseases.

  8. The role of silicon in enhancing resistance to bacterial blight of hydroponic- and soil-cultured rice

    PubMed Central

    Song, Alin; Xue, Gaofeng; Cui, Peiyuan; Fan, Fenliang; Liu, Hongfang; Yin, Chang; Sun, Wanchun; Liang, Yongchao

    2016-01-01

    Here we report for the first time that bacterial blight of rice can be alleviated by silicon (Si) added. In both inoculated and uninoculated plants, shoot dry weight was significantly higher in the +Si plants than in the −Si plants. A soil-cultured trial showed that disease severity was 24.3% lower in the Si-amended plants than in the non-Si-amended plants. Plants that were switched from −Si to +Si nutrient solution and simultaneously inoculated with Xoo also exhibited the same high resistance to bacterial blight as the plants that were treated continuously with Si, with control efficiencies of 52.8 and 62.9%, respectively. Moreover, total concentrations of soluble phenolics and lignin in rice leaves were significantly higher in the +Si plants than in the −Si plants. Polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities in rice leaves were observed to be higher in the +Si plants than in the −Si plants. The expression levels of Os03g0109600, Prla, Rcht2 and Lox2osPil, were also higher in +Si plants than in −Si plants post-inoculation during the experimental time. Addition of Si resulted in increased Pal transcription, and inhibited CatA and Os03g0126000 expression in the earlier and later stages of bacterial inoculation, respectively. PMID:27091552

  9. Bacterial resistance of self-assembled surfaces using PPOm-b-PSBMAn zwitterionic copolymer - concomitant effects of surface topography and surface chemistry on attachment of live bacteria.

    PubMed

    Hsiao, Sheng-Wen; Venault, Antoine; Yang, Hui-Shan; Chang, Yung

    2014-06-01

    Three well-defined diblock copolymers made of poly(sulfobetaine methacrylate) (poly(SBMA)) and poly(propylene oxide) (PPO) groups were synthesized by atom transfer radical polymerization (ATRP) method. They were physically adsorbed onto three types of surfaces having different topography, including smooth flat surface, convex surface, and indented surface. Chemical state of surfaces was characterized by XPS while the various topographies were examined by SEM and AFM. Hydrophilicity of surfaces was dependent on both the surface chemistry and the surface topography, suggesting that orientation of copolymer brushes can be tuned in the design of surfaces aimed at resisting bacterial attachment. Escherichia coli, Staphylococcus epidermidis, Streptococcus mutans and Escherichia coli with green fluorescent protein (E. coli GFP) were used in bacterial tests to assess the resistance to bacterial attachment of poly(SBMA)-covered surfaces. Results highlighted a drastic improvement of resistance to bacterial adhesion with the increasing of poly(SBMA) to PPO ratio, as well as an important effect of surface topography. The chemical effect was directly related to the length of the hydrophilic moieties. When longer, more water could be entrapped, leading to improved anti-bacterial properties. The physical effect impacted on the orientation of the copolymer brushes, as well as on the surface contact area available. Convex surfaces as well as indented surfaces wafer presented the best resistance to bacterial adhesion. Indeed, bacterial attachment was more importantly reduced on these surfaces compared with smooth surfaces. It was explained by the non-orthogonal orientation of copolymer brushes, resulting in a more efficient surface coverage of zwitterionic molecules. This work suggests that not only the control of surface chemistry is essential in the preparation of surfaces resisting bacterial attachment, but also the control of surface topography and orientation of antifouling

  10. Mapping quantitative trait loci associated with resistance to bacterial spot (Xanthomonas arboricola pv. pruni) in peach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial spot, caused by Xanthomonas arboricola pv. pruni (Xap), is a serious disease that can affect peach fruit quality and production worldwide. This disease causes severe defoliation and blemishing of fruit, particularly in areas with high rainfall, strong winds, high humidity, and sandy soil. ...

  11. Monitoring bacterial panicle blight disease of rice and germplasm evaluation for resistance in Arkansas in 2015

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice is a major cereal crop that contributes significantly to the global food security. Rice production is challenged by both abiotic and biotic stresses. Rice bacterial panicle blight (BPB) has been recognized as one of the major biotic factors that can cause severe yield loss in Southern rice stat...

  12. Registration of common bacterial blight resistant cranberry dry bean germplasm line USCR-CBB-20

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common bacterial blight is a serious disease of dry edible beans in warm humid climates. The disease is most prominent east of the continental divide in the U.S. Large seeded dry beans from the Andean gene pool, such as those in the cranberry bean market class are very susceptible to this disease. ...

  13. Spleen size is an indirect indicator of rainbow trout bacterial cold water disease resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The contribution of the spleen to anti-bacterial immunity in lower vertebrates is poorly understood. The spleen first appears as a recognizable organ in shark and bony fish lineages while factors influencing its size and functions in lower vertebrates have received little attention. We have previou...

  14. Pasteurization Procedures for Donor Human Milk Affect Body Growth, Intestinal Structure, and Resistance against Bacterial Infections in Preterm Pigs.

    PubMed

    Li, Yanqi; Nguyen, Duc Ninh; de Waard, Marita; Christensen, Lars; Zhou, Ping; Jiang, Pingping; Sun, Jing; Bojesen, Anders Miki; Lauridsen, Charlotte; Lykkesfeldt, Jens; Dalsgaard, Trine Kastrup; Bering, Stine Brandt; Sangild, Per Torp

    2017-03-15

    Background: Holder pasteurization (HP) destroys multiple bioactive factors in donor human milk (DM), and UV-C irradiation (UVC) is potentially a gentler method for pasteurizing DM for preterm infants.Objective: We investigated whether UVC-treated DM improves gut maturation and resistance toward bacterial infections relative to HP-treated DM.Methods: Bacteria, selected bioactive components, and markers of antioxidant capacity were measured in unpasteurized donor milk (UP), HP-treated milk, and UVC-treated milk (all from the same DM pool). Fifty-seven cesarean-delivered preterm pigs (91% gestation; ratio of males to females, 30:27) received decreasing volumes of parental nutrition (average 69 mL ⋅ kg(-1) ⋅ d(-1)) and increasing volumes of the 3 DM diets (n = 19 each, average 89 mL ⋅ kg(-1) ⋅ d(-1)) for 8-9 d. Body growth, gut structure and function, and systemic bacterial infection were evaluated.Results: A high bacterial load in the UP (6×10(5) colony forming units/mL) was eliminated similarly by HP and UVC treatments. Relative to HP-treated milk, both UVC-treated milk and UP showed greater activities of lipase and alkaline phosphatase and concentrations of lactoferrin, secretory immunoglobulin A, xanthine dehydrogenase, and some antioxidant markers (all P < 0.05). The pigs fed UVC-treated milk and pigs fed UP showed higher relative weight gain than pigs fed HP-treated milk (5.4% and 3.5%), and fewer pigs fed UVC-treated milk had positive bacterial cultures in the bone marrow (28%) than pigs fed HP-treated milk (68%) (P < 0.05). Intestinal health was also improved in pigs fed UVC-treated milk compared with those fed HP-treated milk as indicated by a higher plasma citrulline concentration (36%) and villus height (38%) (P < 0.05) and a tendency for higher aminopeptidase N (48%) and claudin-4 (26%) concentrations in the distal intestine (P < 0.08). The gut microbiota composition was similar among groups except for greater proportions of Enterococcus in pigs

  15. Enhanced biofilm formation and increased resistance to antimicrobial agents and bacterial invasion are caused by synergistic interactions in multispecies biofilms.

    PubMed

    Burmølle, Mette; Webb, Jeremy S; Rao, Dhana; Hansen, Lars H; Sørensen, Søren J; Kjelleberg, Staffan

    2006-06-01

    Most biofilms in their natural environments are likely to consist of consortia of species that influence each other in synergistic and antagonistic manners. However, few reports specifically address interactions within multispecies biofilms. In this study, 17 epiphytic bacterial strains, isolated from the surface of the marine alga Ulva australis, were screened for synergistic interactions within biofilms when present together in different combinations. Four isolates, Microbacterium phyllosphaerae, Shewanella japonica, Dokdonia donghaensis, and Acinetobacter lwoffii, were found to interact synergistically in biofilms formed in 96-well microtiter plates: biofilm biomass was observed to increase by >167% in biofilms formed by the four strains compared to biofilms composed of single strains. When exposed to the antibacterial agent hydrogen peroxide or tetracycline, the relative activity (exposed versus nonexposed biofilms) of the four-species biofilm was markedly higher than that in any of the single-species biofilms. Moreover, in biofilms established on glass surfaces in flow cells and subjected to invasion by the antibacterial protein-producing Pseudoalteromonas tunicata, the four-species biofilms resisted invasion to a greater extent than did the biofilms formed by the single species. Replacement of each strain by its cell-free culture supernatant suggested that synergy was dependent both on species-specific physical interactions between cells and on extracellular secreted factors or less specific interactions. In summary, our data strongly indicate that synergistic effects promote biofilm biomass and resistance of the biofilm to antimicrobial agents and bacterial invasion in multispecies biofilms.

  16. Functional studies of cochleate assemblies of an oligo-acyl-lysyl with lipid mixtures for combating bacterial multidrug resistance.

    PubMed

    Sarig, Hadar; Ohana, Dafna; Epand, Raquel F; Mor, Amram; Epand, Richard M

    2011-10-01

    The cationic antimicrobial oligo-acyl-lysyls (OAKs) interact with lipid mixtures mimicking the composition of bacterial cytoplasmic membranes. We have reported the ability of one such OAK, C(12)K-7α(8), to cluster anionic lipids and to promote a structural change with lipid bilayers to form rolled cylindrical structures or cochleates, without requiring divalent cations for their assembly. These assemblies can be exploited for drug delivery, permitting their synergistic use with antibiotics in systemic therapy to increase efficacy and reduce toxicity. Our previous studies of the biophysical properties of these systems led us to select mixtures with the goal of optimizing their potential for enhancing effectiveness in combating bacterial multidrug resistance. Here, we further investigate the properties of such mixtures that result in enhanced in vivo activity. The role of erythromycin in the assembly of cochleates with OAK in the gel and the liquid crystalline states were assessed, as well as the encapsulation efficiency of the systems chosen. In addition, we found that erythromycin did not undermine the ability of OAKs to induce fusion of vesicles, fusion being an essential component of cochleate formation. The in vivo activity of the new assemblies tested resulted in higher survival rates of animals infected with multidrug resistant bacteria.

  17. Accumulation of clinically relevant antibiotic-resistance genes, bacterial load, and metals in freshwater lake sediments in Central Europe.

    PubMed

    Devarajan, Naresh; Laffite, Amandine; Graham, Neil D; Meijer, Maria; Prabakar, Kandasamy; Mubedi, Josué I; Elongo, Vicky; Mpiana, Pius T; Ibelings, Bastiaan Willem; Wildi, Walter; Poté, John

    2015-06-02

    Wastewater treatment plants (WWTP) receive the effluents from various sources (communities, industrial, and hospital effluents) and are recognized as reservoir for antibiotic-resistance genes (ARGs) that are associated with clinical pathogens. The aquatic environment is considered a hot-spot for horizontal gene transfer, and lake sediments offer the opportunity for reconstructing the pollution history and evaluating the impacts. In this context, variation with depth and time of the total bacterial load, the abundance of faecal indicator bacteria (FIB; E. coli and Enterococcus spp. (ENT)), Pseudomonas spp., and ARGs (blaTEM, blaSHV, blaCTX-M, blaNDM, and aadA) were quantified in sediment profiles of different parts of Lake Geneva using quantitative PCR. The abundance of bacterial marker genes was identified in sediments contaminated by WWTP following eutrophication of the lake. Additionally, ARGs, including the extended-spectrum ß-lactam- and aminoglycoside-resistance genes, were identified in the surface sediments. The ARG and FIB abundance strongly correlated (r ≥ 0.403, p < 0.05, n = 34) with organic matter and metal concentrations in the sediments, indicating a common and contemporary source of contamination. The contamination of sediments by untreated or partially treated effluent water can affect the quality of ecosystem. Therefore, the reduction of contaminants from the source is recommended for further improvement of water quality.

  18. Sulfamethoxazole and COD increase abundance of sulfonamide resistance genes and change bacterial community structures within sequencing batch reactors.

    PubMed

    Guo, Xueping; Pang, Weihai; Dou, Chunling; Yin, Daqiang

    2017-05-01

    The abundant microbial community in biological treatment processes in wastewater treatment plants (WWTPs) may potentially enhance the horizontal gene transfer of antibiotic resistance genes with the presence of antibiotics. A lab-scale sequencing batch reactor was designed to investigate response of sulfonamide resistance genes (sulI, sulII) and bacterial communities to various concentrations of sulfamethoxazole (SMX) and chemical oxygen demand (COD) of wastewater. The SMX concentrations (0.001 mg/L, 0.1 mg/L and 10 mg/L) decreased with treatment time and higher SMX level was more difficult to remove. The presence of SMX also significantly reduced the removal efficiency of ammonia nitrogen, affecting the normal function of WWTPs. All three concentrations of SMX raised both sulI and sulII genes with higher concentrations exhibiting greater increases. The abundance of sul genes was positive correlated with treatment time and followed the second-order reaction kinetic model. Interestingly, these two genes have rather similar activity. SulI and sulII gene abundance also performed similar response to COD. Simpson index and Shannon-Weiner index did not show changes in the microbial community diversity. However, the 16S rRNA gene cloning and sequencing results showed the bacterial community structures varied during different stages. The results demonstrated that influent antibiotics into WWTPs may facilitate selection of ARGs and affect the wastewater conventional treatment as well as the bacteria community structures.

  19. Influence of Rice Development on the Function of Bacterial Blight Resistance Genes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Disease resistance genes most commonly used in breeding programs are single, dominant, resistance (R) genes with relative effectiveness influenced by plant developmental stage. Knowing the developmental stages at which an R gene is functional is important for disease management. In rice, resistanc...

  20. Influence of temperature regimes on resistance gene-mediated response to rice bacterial blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing temperatures could reduce yield growth rate of rice by 10% in several rice production areas. Similarly, higher temperatures are predicted to accelerate the breakdown of plant disease resistance through higher disease pressure or altered resistance (R) gene effectiveness in many host-path...

  1. Heavy-Metal and Antibiotic Resistance in the Bacterial Flora of Sediments of New York Bight

    PubMed Central

    Timoney, J. F.; Port, Jennifer; Giles, Janis; Spanier, J.

    1978-01-01

    The New York Bight extends seaward some 80 to 100 miles (ca. 129 to 161 km) from the Long Island and New Jersey shorelines to the edge of the continental shelf. Over 14 × 106 m3 of sewage sludge, dredge spoils, acid wastes, and cellar dirt are discharged into this area each year. Large populations of Bacillus sp. resistant to 20 μg of mercury per ml were observed in Bight sediments contaminated by these wastes. Resistant Bacillus populations were much greater in sediments containing high concentrations of Hg and other heavy metals than in sediments from areas further offshore where dumping has never been practiced and where heavy-metal concentrations were found to be low. Ampicillin resistance due mainly to β-lactamase production was significantly (P < 0.001) more frequent in Bacillus strains from sediments near the sewage sludge dump site than in similar Bacillus populations from control sediments. Bacillus strains with combined ampicillin and Hg resistances were almost six times as frequent at the sludge dump site as in control sediments. This observation suggests that genes for Hg resistance and β-lactamase production are simultaneously selected for in Bacillus and that heavy-metal contamination of an ecosystem can result in a selection pressure for antibiotic resistance in bacteria in that system. Also, Hg resistance was frequently linked with other heavy-metal resistances and, in a substantial proportion of Bacillus strains, involved reduction to volatile metallic Hg (Hg°). PMID:727779

  2. Trends in antimicrobial resistance in equine bacterial isolates: 1999-2012.

    PubMed

    Johns, I C; Adams, E-L

    2015-03-28

    This study aimed to identify changing antimicrobial resistance patterns in isolates commonly obtained from equine clinical submissions. Laboratory records from 1999 to 2012 were searched for equine samples from which Escherichia coli or Streptococcus species was isolated. Susceptibility to enrofloxacin, ceftiofur, gentamicin, penicillin G, trimethoprim sulfamethoxazole (TMPS) and tetracyclines was noted. Isolates were divided into those identified between 1999 and 2004 (Early) and between 2007 and 2012 (Late). The proportion of isolates resistant to each antimicrobial and multiple drug-resistant (MDR) isolates (≥3 antimicrobial classes) was compared between time periods. There were 464 isolates identified (242 Early; 222 Late). A significant increase in the percentage of E coli isolates resistant to ceftiofur (7.3-22.7 per cent, P=0.002), gentamicin (28.5-53.9 per cent, P<0.001), tetracyclines (48.4-74.2 per cent, P=0.002) and MDR (26.6-49.4 per cent, P=0.007) was identified. There was a significant increase over time in the percentage of all streptococcal species resistant to enrofloxacin, ranging from 0 per cent (Early) up to 63 per cent (Late) depending on species. For Streptococcus zooepidemicus, resistance over time to tetracyclines and MDR increased. There was also a decrease in the proportion of S zooepidemicus resistant to TMPS over time. An increase in resistance over time of common equine pathogens to a number of commonly used antimicrobials supports the responsible use of antimicrobials.

  3. EDS1 mediates pathogen resistance and virulence function of a bacterial effector in soybean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Enhanced disease susceptibility 1 (EDS1) and phytoalexin deficient 4 (PAD4) are well known regulators of both basal and resistance (R) protein-mediated plant defense. We identified two EDS1- (GmEDS1a/b) and one PAD4-like (GmPAD4) protein that are required for resistance signaling in soybean. Consist...

  4. Protein, cell and bacterial fouling resistance of polypeptoid-modified surfaces: effect of side-chain chemistry†

    PubMed Central

    Statz, Andrea R.; Barron, Annelise E.; Messersmith, Phillip B.

    2011-01-01

    Peptidomimetic polymers consisting of poly-N-substituted glycine oligomers (polypeptoids) conjugated to biomimetic adhesive polypeptides were investigated as antifouling surface coatings. The polymers were immobilized onto TiO2 surfaces via an anchoring peptide consisting of alternating residues of 3,4-dihydroxyphenylalanine (DOPA) and lysine. Three polypeptoid side-chain compositions were investigated for antifouling performance and stability toward enzymatic degradation. Ellipsometry and XPS analysis confirmed that purified polymers adsorbed strongly to TiO2 surfaces, and the immobilized polymers were resistant to enzymatic degradation as demonstrated by mass spectrometry. All polypeptoid-modified surfaces exhibited significant reductions in adsorption of lysozyme, fibrinogen and serum proteins, and were resistant to 3T3 fibroblast cell attachment for up to seven days. Long-term in vitro cell attachment studies conducted for six weeks revealed the importance of polypeptoid side-chain composition, with a methoxyethyl side chain providing superior long-term fouling resistance compared to hydroxyethyl and hydroxypropyl side chains. Finally, attachment of both gram-positive and gram-negative bacteria for up to four days under continuous-flow conditions was significantly reduced on the polypeptoid-modified surfaces compared to unmodified TiO2 surfaces. The results reveal the influence of polypeptoid side-chain chemistry on short-term and long-term protein, cell and bacterial fouling resistance. PMID:21472038

  5. Ectopic expression of Tsi1 in transgenic hot pepper plants enhances host resistance to viral, bacterial, and oomycete pathogens.

    PubMed

    Shin, Ryoung; Park, Jeong Mee; An, Jong-Min; Paek, Kyung-Hee

    2002-10-01

    In many plants, including hot pepper plants, productivity is greatly affected by pathogen attack. We reported previously that tobacco stress-induced gene 1 (Tsi1) may play an important role in regulating stress responsive genes and pathogenesis-related (PR) genes. In this study, we demonstrated that overexpression of Tsi1 gene in transgenic hot pepper plants induced constitutive expression of several PR genes in the absence of stress or pathogen treatment. The transgenic hot pepper plants expressing Tsi1 exhibited resistance to Pepper mild mottle virus (PMMV) and Cucumber mosaic virus (CMV). Furthermore, these transgenic plants showed increased resistance to a bacterial pathogen, Xanthomonas campestris pv. vesicatoria and also an oomycete pathogen, Phytophthora capsici. These results suggested that ectopic expression of Tsi1 in transgenic hot pepper plants enhanced the resistance of the plants to various pathogens, including viruses, bacteria, and oomycete. These results suggest that using transcriptional regulatory protein genes may contribute to developing broad-spectrum resistance in crop plants.

  6. Low-Concentration Ciprofloxacin Selects Plasmid-Mediated Quinolone Resistance Encoding Genes and Affects Bacterial Taxa in Soil Containing Manure

    PubMed Central

    Huang, Ting; Xu, Ying; Zeng, Jie; Zhao, Dong-Hao; Li, Liang; Liao, Xiao-Ping; Liu, Ya-Hong; Sun, Jian

    2016-01-01

    The spread of antimicrobial resistance in environment is promoted at least in part by the inappropriate use of antibiotics in animals and humans. The present study was designed to investigate the impact of different concentrations of ciprofloxacin in soil containing manure on the development of plasmid-mediated quinolone resistance (PMQR) – encoding genes and the abundance of soil bacterial communities. For these studies, high-throughput next-generation sequencing of 16S rRNA, real-time polymerase chain reaction and standard microbiologic culture methods were utilized. We demonstrated that the dissipate rate of relative abundances of some of PMQR-encoding genes, such as qnrS, oqxA and aac(6′)-Ib-cr, were significantly lower with ciprofloxacin 0.04 and 0.4 mg/kg exposure as compared to no-ciprofloxacin control and ciprofloxacin 4 mg/kg exposure during 2 month. Also, the number of ciprofloxacin resistant bacteria was significantly greater in ciprofloxacin 0.04 and 0.4 mg/kg exposure as compared with no-ciprofloxacin control and the ciprofloxacin 4 mg/kg exposure. In addition, lower ciprofloxacin concentration provided a selective advantage for the populations of Xanthomonadales and Bacillales in orders while Agrobacterium, Bacillus, Enterococcus, and Burkholderia in genera. These findings suggest that lower concentration of ciprofloxacin resulted in a slower rate of PMQR-encoding genes dissipation and selected development of ciprofloxacin-resistant bacteria in soil amended with manure. PMID:27847506

  7. Identification of two AFLP markers linked to bacterial wilt resistance in tomato and conversion to SCAR markers.

    PubMed

    Miao, Lixiang; Shou, Senyan; Cai, Jiayan; Jiang, Fang; Zhu, Zhujun; Li, Hongbin

    2009-03-01

    Tomato bacterial wilt (BW) incited by Ralstonia solanacearum is a constraint on tomato production in tropical, subtropical and humid regions of the world. In this paper, we present the results of a research aimed at the identification of PCR-based markers amplified fragment length polymorphism (AFLP) linked to the genes that confer resistance to tomato BW. To this purpose, bulked segregant analysis was applied to an F(2) population segregating for the BW resistant gene and derived from the pair-cross between a BW resistant cultivar T51A and the susceptible cultivar T9230. Genetic analysis indicated that tomato BW was conferred by two incomplete dominant genes. A CTAB method for total DNA extraction, developed by Murray and Thompson with some modifications was used to isolation the infected tomato leaves. Thirteen differential fragments were detected using 256 primer combinations, and two AFLP markers were linked to the BW resistance. Subsequently, the AFLP markers were converted to co-dominant SCAR markers, named TSCAR(AAT/CGA) and TSCAR(AAG/CAT). Linkage analysis showed that the two markers are on the contralateral side of TRSR-1. Genetic distance between TSCAR(AAT/CGA) and TRS-1 was estimated to 4.6 cM, while 8.4 cM between TSCAR(AAG/CAT) and TRS-1.

  8. Over-expression of rice leucine-rich repeat protein results in activation of defense response, thereby enhancing resistance to bacterial soft rot in Chinese cabbage.

    PubMed

    Park, Young Ho; Choi, Changhyun; Park, Eun Mi; Kim, Hyo Sun; Park, Hong Jae; Bae, Shin Cheol; Ahn, Ilpyung; Kim, Min Gab; Park, Sang Ryeol; Hwang, Duk-Ju

    2012-10-01

    Pectobacterium carotovorum subsp. carotovorum causes soft rot disease in various plants, including Chinese cabbage. The simple extracellular leucine-rich repeat (eLRR) domain proteins have been implicated in disease resistance. Rice leucine-rich repeat protein (OsLRP), a rice simple eLRR domain protein, is induced by pathogens, phytohormones, and salt. To see whether OsLRP enhances disease resistance to bacterial soft rot, OsLRP was introduced into Chinese cabbage by Agrobacterium-mediated transformation. Two independent transgenic lines over-expressing OsLRP were generated and further analyzed. Transgenic lines over-expressing OsLRP showed enhanced disease resistance to bacterial soft rot compared to non-transgenic control. Bacterial growth was retarded in transgenic lines over-expressing OsLRP compared to non-transgenic controls. We propose that OsLRP confers enhanced resistance to bacterial soft rot. Monitoring expression of defense-associated genes in transgenic lines over-expressing OsLRP, two different glucanases and Brassica rapa polygalacturonase inhibiting protein 2, PDF1 were constitutively activated in transgenic lines compared to non-transgenic control. Taken together, heterologous expression of OsLRP results in the activation of defense response and enhanced resistance to bacterial soft rot.

  9. Antibiotic resistance in bacterial pathogens from retail raw meats and food-producing animals in Japan.

    PubMed

    Hiroi, Midori; Kawamori, Fumihiko; Harada, Tetsuya; Sano, Yono; Miwa, Norinaga; Sugiyama, Kanji; Hara-Kudo, Yukiko; Masuda, Takashi

    2012-10-01

    To determine the prevalence and antimicrobial susceptibility profiles of Campylobacter, Salmonella, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and vancomycin-resistant enterococci (VRE) in food-producing animals and retail raw meats in Japan, raw meat samples as well as food-producing animal feces, cutaneous swabs, and nasal swabs collected from 2004 to 2006 were analyzed. Isolation rates of Campylobacter jejuni and Campylobacter coli, Salmonella, and S. aureus were 34.6% (363 of 1,050), 2.7% (28 of 1,050), and 32.8% (238 of 725), respectively. MRSA was isolated from 3% (9 of 300) of meat samples. No VRE were isolated in this study. Antibiotic resistance in C. coli was higher than that in C. jejuni. Three C. jejuni isolates from a patient with diarrhea in a hospital of Shizuoka Prefecture and two chicken samples that exhibited resistance to ciprofloxacin had identical pulsed-field gel electrophoresis patterns, suggesting that ciprofloxacin-resistant C. jejuni could have been distributed in meat. S. aureus isolates showed the highest level of resistance to ampicillin and tetracycline. Resistance to tetracycline in S. aureus isolates from beef was lower than that seen in isolates from chicken and pork (P < 0.01). This study revealed that the prevalence of MRSA and VRE were low in food-producing animals and retail domestic meats in Japan, although Campylobacter isolates resistant to fluoroquinolone and erythromycin were detected. The occurrence of antimicrobial-resistant pathogens should be monitored continuously to improve the management of the risks associated with antimicrobial drug resistance transferred from food-producing animals to humans.

  10. The genetic architecture of defence as resistance to and tolerance of bacterial infection in Drosophila melanogaster.

    PubMed

    Howick, Virginia M; Lazzaro, Brian P

    2017-03-01

    Defence against pathogenic infection can take two forms: resistance and tolerance. Resistance is the ability of the host to limit a pathogen burden, whereas tolerance is the ability to limit the negative consequences of infection at a given level of infection intensity. Evolutionarily, a tolerance strategy that is independent of resistance could allow the host to avoid mounting a costly immune response and, theoretically, to avoid a co-evolutionary arms race between pathogen virulence and host resistance. Biomedically, understanding the mechanisms of tolerance and how they relate to resistance could potentially yield treatment strategies that focus on health improvement instead of pathogen elimination. To understand the impact of tolerance on host defence and identify genetic variants that determine host tolerance, we defined genetic variation in tolerance as the residual deviation from a binomial regression of fitness under infection against infection intensity. We then performed a genomewide association study to map the genetic basis of variation in resistance to and tolerance of infection by the bacterium Providencia rettgeri. We found a positive genetic correlation between resistance and tolerance, and we demonstrated that the level of resistance is highly predictive of tolerance. We identified 30 loci that predict tolerance, many of which are in genes involved in the regulation of immunity and metabolism. We used RNAi to confirm that a subset of mapped genes have a role in defence, including putative wound repair genes grainy head and debris buster. Our results indicate that tolerance is not an independent strategy from resistance, but that defence arises from a collection of physiological processes intertwined with canonical immunity and resistance.

  11. Turbot (Scophthalmus maximus) hepcidin-1 and hepcidin-2 possess antimicrobial activity and promote resistance against bacterial and viral infection.

    PubMed

    Zhang, Jian; Yu, Lan-Ping; Li, Mo-Fei; Sun, Li

    2014-05-01

    Hepcidin is an antimicrobial peptide and a regulator of iron homeostasis. In turbot (Scophthalmus maximus), two types of hepcidins have been identified, which share approximately 50% sequence identity. In this study, we examined the antimicrobial potentials of the two hepcidins in the form of synthesized peptides, SmHep1P and SmHep2P. We found that SmHep1P and SmHep2P exhibited apparent bactericidal activities against both Gram-positive and Gram-negative bacteria in a dose-dependent manner. The bactericidal effect of SmHep1P was stronger against Gram-positive bacteria, while the bactericidal effect of SmHep2P was stronger against Gram-negative bacteria. Fluorescence and electron microscopy showed that both peptides were able to bind to the target bacterial cells and alter the surface structure of the cells. In vitro studies showed that SmHep1P and SmHep2P reduced bacterial invasion into cultured fish cells. In vivo studies showed that turbot administered with SmHep1P and SmHep2P exhibited significantly enhanced resistance against bacterial and viral infection. In both in vivo and in vitro studies, the antimicrobial activities of SmHep2P were in most cases significantly stronger than those of SmHep1P. Together these results indicate that the two hepcidins of turbot most likely possess antimicrobial properties and play a role in the innate immune defense against bacterial and viral pathogens.

  12. Size-related bacterial diversity and tetracycline resistance gene abundance in the air of concentrated poultry feeding operations.

    PubMed

    Gao, Min; Jia, Ruizhi; Qiu, Tianlei; Han, Meilin; Wang, Xuming

    2017-01-01

    Concentrated animal-feeding operations (CAFOs) are considered a source of airborne human pathogens and antibiotic resistance genes. Although bacterial abundance and diversity have been well studied, limited information on the size distribution of bioaerosols has prevented a clear understanding of the health effects of exposure to bioaerosols from CAFOs. Here, different sizes of particles were sampled from the inside and outside of atmospheric environments of layer and broiler feeding operations using 8-stage Andersen samplers. The quantitative real-time polymerase chain reaction (qPCR) and 16S rDNA-based sequencing were used to analyze the characteristics of biological abundance and diversity, respectively, according to size. The results indicated that size-related differences occurred in terms of airborne bacterial richness, diversity, and concentration at poultry-feeding operations. The richness of biological genera in the urban atmospheric environment was lower than in concentrated poultry-feeding operations. The biological diversity of airborne bacterial genera, including genera associated with potential pathogens, varied according to size. The bacterial lineages of bioaerosols present in the 7 size stages for layers clustered apart from those for broilers, suggesting that the type of poultry house is a more important factor than the particle size in shaping the microbial communities. In most cases, the concentrations of the 16S rDNA, Escherichia coli, tetW, and tetL genes increased as the particle size increased, with the geometric mean diameters varying from 4.7 to 5.8 μm. These results regarding the size-related differences in the diversity and abundance of bioaerosols will facilitate a better understanding of the potential health impact on both poultry and humans working in such environments.

  13. Synergistic and Additive Effect of Oregano Essential Oil and Biological Silver Nanoparticles against Multidrug-Resistant Bacterial Strains

    PubMed Central

    Scandorieiro, Sara; de Camargo, Larissa C.; Lancheros, Cesar A. C.; Yamada-Ogatta, Sueli F.; Nakamura, Celso V.; de Oliveira, Admilton G.; Andrade, Célia G. T. J.; Duran, Nelson; Nakazato, Gerson; Kobayashi, Renata K. T.

    2016-01-01

    Bacterial resistance to conventional antibiotics has become a clinical and public health problem, making therapeutic decisions more challenging. Plant compounds and nanodrugs have been proposed as potential antimicrobial alternatives. Studies have shown that oregano (Origanum vulgare) essential oil (OEO) and silver nanoparticles have potent antibacterial activity, also against multidrug-resistant strains; however, the strong organoleptic characteristics of OEO and the development of resistance to these metal nanoparticles can limit their use. This study evaluated the antibacterial effect of a two-drug combination of biologically synthesized silver nanoparticles (bio-AgNP), produced by Fusarium oxysporum, and OEO against Gram-positive and Gram-negative bacteria, including multidrug-resistant strains. OEO and bio-AgNP showed bactericidal effects against all 17 strains tested, with minimal inhibitory concentrations (MIC) ranging from 0.298 to 1.193 mg/mL and 62.5 to 250 μM, respectively. Time-kill curves indicated that OEO acted rapidly (within 10 min), while the metallic nanoparticles took 4 h to kill Gram-negative bacteria and 24 h to kill Gram-positive bacteria. The combination of the two compounds resulted in a synergistic or additive effect, reducing their MIC values and reducing the time of action compared to bio-AgNP used alone, i.e., 20 min for Gram-negative bacteria and 7 h for Gram-positive bacteria. Scanning electron microscopy (SEM) revealed similar morphological alterations in Staphylococcus aureus (non-methicillin-resistant S. aureus, non-MRSA) cells exposed to three different treatments (OEO, bio-AgNP and combination of the two), which appeared cell surface blebbing. Individual and combined treatments showed reduction in cell density and decrease in exopolysaccharide matrix compared to untreated bacterial cells. It indicated that this composition have an antimicrobial activity against S. aureus by disrupting cells. Both compounds showed very low

  14. Rice WRKY45 plays important roles in fungal and bacterial disease resistance.

    PubMed

    Shimono, Masaki; Koga, Hironori; Akagi, Aya; Hayashi, Nagao; Goto, Shingo; Sawada, Miyuki; Kurihara, Takayuki; Matsushita, Akane; Sugano, Shoji; Jiang, Chang-Jie; Kaku, Hisatoshi; Inoue, Haruhiko; Takatsuji, Hiroshi

    2012-01-01

    Plant 'activators', such as benzothiadiazole (BTH), protect plants from various diseases by priming the plant salicylic acid (SA) signalling pathway. We have reported previously that a transcription factor identified in rice, WRKY45 (OsWRKY45), plays a pivotal role in BTH-induced disease resistance by mediating SA signalling. Here, we report further functional characterization of WRKY45. Different plant activators vary in their action points, either downstream (BTH and tiadinil) or upstream (probenazole) of SA. Rice resistance to Magnaporthe grisea, induced by both types of plant activator, was markedly reduced in WRKY45-knockdown (WRKY45-kd) rice, indicating a universal role for WRKY45 in chemical-induced resistance. Fungal invasion into rice cells was blocked at most attempted invasion sites (pre-invasive defence) in WRKY45-overexpressing (WRKY45-ox) rice. Hydrogen peroxide accumulated within the cell wall underneath invading fungus appressoria or between the cell wall and the cytoplasm, implying a possible role for H(2)O(2) in pre-invasive defence. Moreover, a hypersensitive reaction-like reaction was observed in rice cells, in which fungal growth was inhibited after invasion (post-invasive defence). The two levels of defence mechanism appear to correspond to Type I and II nonhost resistances. The leaf blast resistance of WRKY45-ox rice plants was much higher than that of other known blast-resistant varieties. WRKY45-ox plants also showed strong panicle blast resistance. BTH-induced resistance to Xanthomonas oryzae pv. oryzae was compromised in WRKY45-kd rice, whereas WRKY45-ox plants were highly resistant to this pathogen. However, WRKY45-ox plants were susceptible to Rhizoctonia solani. These results indicate the versatility and limitations of the application of this gene.

  15. Rapid identification of bacterial resistance to Ciprofloxacin using surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kastanos, Evdokia; Hadjigeorgiou, Katerina; Pitris, Costas

    2014-02-01

    Due to its effectiveness and broad coverage, Ciprofloxacin is the fifth most prescribed antibiotic in the US. As current methods of infection diagnosis and antibiotic sensitivity testing (i.e. an antibiogram) are very time consuming, physicians prescribe ciprofloxacin before obtaining antibiogram results. In order to avoid increasing resistance to the antibiotic, a method was developed to provide both a rapid diagnosis and the sensitivity to the antibiotic. Using Surface Enhanced Raman Spectroscopy, an antibiogram was obtained after exposing the bacteria to Ciprofloxacin for just two hours. Spectral analysis revealed clear separation between sensitive and resistant bacteria and could also offer some inside into the mechanisms of resistance.

  16. Development of Gene-Pyramid Lines of the Elite Restorer Line, RPHR-1005 Possessing Durable Bacterial Blight and Blast Resistance.

    PubMed

    Abhilash Kumar, V; Balachiranjeevi, C H; Bhaskar Naik, S; Rambabu, R; Rekha, G; Harika, G; Hajira, S K; Pranathi, K; Anila, M; Kousik, M; Vijay Kumar, S; Yugander, A; Aruna, J; Dilip Kumar, T; Vijaya Sudhakara Rao, K; Hari Prasad, A S; Madhav, M S; Laha, G S; Balachandran, S M; Prasad, M S; Viraktamath, B C; Ravindra Babu, V; Sundaram, R M

    2016-01-01

    RPHR-1005, the stable restorer line of the popular medium slender (MS) grain type rice hybrid, DRRH-3 was improved in this study for resistance against bacterial blight (BB) and blast diseases through marker-assisted backcross breeding (MABB). In this study, four major resistance genes (i.e., Xa21 and Xa33 for BB resistance and Pi2 and Pi54 for blast resistance) have been transferred to RPHR-1005 using RPBio Patho-1 (possessing Xa21 + Pi2), RPBio Patho-2 (possessing Xa21 + Pi54) and FBR1-15EM (possessing Xa33) as the donors. Foreground selection was carried out using PCR-based molecular markers specific for the target resistance genes and the major fertility restorer genes, Rf3 and Rf4, while background selection was carried out using a set of parental polymorphic rice SSR markers and backcrossing was continued uptoBC2 generation. At BC2F2, plants possessing the gene combination- Xa21 + Pi2, Xa21 + Pi54 and Xa33 in homozygous condition and with >92% recovery of the recurrent parent genome (RPG) were identified and intercrossed to combine all the four resistance genes. Twenty-two homozygous, pyramid lines of RPHR-1005 comprising of three single-gene containing lines, six 2-gene containing lines, eight 3-gene containing lines, and five 4-gene containing lines were identified among the double intercross lines at F3 generation (DICF3). They were then evaluated for their resistance against BB and blast, fertility restoration ability and for key agro-morphological traits. While single gene containing lines were resistant to either BB or blast, the 2-gene, 3-gene, and 4-gene pyramid lines showed good level of resistance against both and/or either of the two diseases. Most of the 2-gene, 3-gene, and 4-gene containing pyramid lines showed yield levels and other key agro-morphological and grain quality traits comparable to the original recurrent parent and showed complete fertility restoration ability, with a few showing higher yield as compared to RPHR-1005. Further, the

  17. Development of Gene-Pyramid Lines of the Elite Restorer Line, RPHR-1005 Possessing Durable Bacterial Blight and Blast Resistance

    PubMed Central

    Abhilash Kumar, V.; Balachiranjeevi, C. H.; Bhaskar Naik, S.; Rambabu, R.; Rekha, G.; Harika, G.; Hajira, S. K.; Pranathi, K.; Anila, M.; Kousik, M.; Vijay Kumar, S.; Yugander, A.; Aruna, J.; Dilip Kumar, T.; Vijaya Sudhakara Rao, K.; Hari Prasad, A. S.; Madhav, M. S.; Laha, G. S.; Balachandran, S. M.; Prasad, M. S.; Viraktamath, B. C.; Ravindra Babu, V.; Sundaram, R. M.

    2016-01-01

    RPHR-1005, the stable restorer line of the popular medium slender (MS) grain type rice hybrid, DRRH-3 was improved in this study for resistance against bacterial blight (BB) and blast diseases through marker-assisted backcross breeding (MABB). In this study, four major resistance genes (i.e., Xa21 and Xa33 for BB resistance and Pi2 and Pi54 for blast resistance) have been transferred to RPHR-1005 using RPBio Patho-1 (possessing Xa21 + Pi2), RPBio Patho-2 (possessing Xa21 + Pi54) and FBR1-15EM (possessing Xa33) as the donors. Foreground selection was carried out using PCR-based molecular markers specific for the target resistance genes and the major fertility restorer genes, Rf3 and Rf4, while background selection was carried out using a set of parental polymorphic rice SSR markers and backcrossing was continued uptoBC2 generation. At BC2F2, plants possessing the gene combination- Xa21 + Pi2, Xa21 + Pi54 and Xa33 in homozygous condition and with >92% recovery of the recurrent parent genome (RPG) were identified and intercrossed to combine all the four resistance genes. Twenty-two homozygous, pyramid lines of RPHR-1005 comprising of three single-gene containing lines, six 2-gene containing lines, eight 3-gene containing lines, and five 4-gene containing lines were identified among the double intercross lines at F3 generation (DICF3). They were then evaluated for their resistance against BB and blast, fertility restoration ability and for key agro-morphological traits. While single gene containing lines were resistant to either BB or blast, the 2-gene, 3-gene, and 4-gene pyramid lines showed good level of resistance against both and/or either of the two diseases. Most of the 2-gene, 3-gene, and 4-gene containing pyramid lines showed yield levels and other key agro-morphological and grain quality traits comparable to the original recurrent parent and showed complete fertility restoration ability, with a few showing higher yield as compared to RPHR-1005. Further, the

  18. Identification of New Drug Targets in Multi-Drug Resistant Bacterial Infections

    DTIC Science & Technology

    2015-06-15

    in either exponential or stationary phase of growth . Once again, the most highly over-expressed genes in the biofilm cultures were the genes that...identify the natural product through in vitro reconstitution and analysis of mutant strains, and assay the role of this pathway in bacterial growth and...group has developed a novel and efficient approach to identify GNB genes and their protein products that are essential for growth and/or survival

  19. Effect of Seed Treatment by Cold Plasma on the Resistance of Tomato to Ralstonia solanacearum (Bacterial Wilt)

    PubMed Central

    Jiang, Jiafeng; Lu, Yufang; Li, Jiangang; Li, Ling; He, Xin; Shao, Hanliang; Dong, Yuanhua

    2014-01-01

    This study investigated the effect of cold plasma seed treatment on tomato bacterial wilt, caused by Ralstonia solanacearum (R. solanacearum), and the regulation of resistance mechanisms. The effect of cold plasma of 80W on seed germination, plant growth, nutrient uptake, disease severity, hydrogen peroxide (H2O2) concentration and activities of peroxidase (POD; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.10.3.2) and phenylalanine ammonia lyase (PAL; EC 4.3.1.5) were examined in tomato plants. Plasma treatment increased tomato resistance to R. solanacearum with an efficacy of 25.0%. Plasma treatment significantly increased both germination and plant growth in comparison with the control treatment, and plasma-treated plants absorbed more calcium and boron than the controls. In addition, H2O2 levels in treated plants rose faster and reached a higher peak, at 2.579 µM gFW−1, 140% greater than that of the control. Activities of POD (421.3 U gFW−1), PPO (508.8 U gFW−1) and PAL (707.3 U gFW−1) were also greater in the treated plants than in the controls (103.0 U gFW−1, 166.0 U gFW−1 and 309.4 U gFW−1, respectively). These results suggest that plasma treatment affects the regulation of plant growth, H2O2 concentration, and POD, PPO and PAL activity in tomato, resulting in an improved resistance to R. solanacearum. Consequently, cold plasma seed treatment has the potential to control tomato bacterial wilt caused by R. solanacearum. PMID:24840508

  20. Effect of seed treatment by cold plasma on the resistance of tomato to Ralstonia solanacearum (Bacterial Wilt).

    PubMed

    Jiang, Jiafeng; Lu, Yufang; Li, Jiangang; Li, Ling; He, Xin; Shao, Hanliang; Dong, Yuanhua

    2014-01-01

    This study investigated the effect of cold plasma seed treatment on tomato bacterial wilt, caused by Ralstonia solanacearum (R. solanacearum), and the regulation of resistance mechanisms. The effect of cold plasma of 80W on seed germination, plant growth, nutrient uptake, disease severity, hydrogen peroxide (H2O2) concentration and activities of peroxidase (POD; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.10.3.2) and phenylalanine ammonia lyase (PAL; EC 4.3.1.5) were examined in tomato plants. Plasma treatment increased tomato resistance to R. solanacearum with an efficacy of 25.0%. Plasma treatment significantly increased both germination and plant growth in comparison with the control treatment, and plasma-treated plants absorbed more calcium and boron than the controls. In addition, H2O2 levels in treated plants rose faster and reached a higher peak, at 2.579 µM gFW-1, 140% greater than that of the control. Activities of POD (421.3 U gFW-1), PPO (508.8 U gFW-1) and PAL (707.3 U gFW-1) were also greater in the treated plants than in the controls (103.0 U gFW-1, 166.0 U gFW-1 and 309.4 U gFW-1, respectively). These results suggest that plasma treatment affects the regulation of plant growth, H2O2 concentration, and POD, PPO and PAL activity in tomato, resulting in an improved resistance to R. solanacearum. Consequently, cold plasma seed treatment has the potential to control tomato bacterial wilt caused by R. solanacearum.

  1. Pre-adapting parasitic phages to a pathogen leads to increased pathogen clearance and lowered resistance evolution with Pseudomonas aeruginosa cystic fibrosis bacterial isolates.

    PubMed

    Friman, V-P; Soanes-Brown, D; Sierocinski, P; Molin, S; Johansen, H K; Merabishvili, M; Pirnay, J-P; De Vos, D; Buckling, A

    2016-01-01

    Recent years have seen renewed interest in phage therapy--the use of viruses to specifically kill disease-causing bacteria--because of the alarming rise in antibiotic resistance. However, a major limitation of phage therapy is the ease at with bacteria can evolve resistance to phages. Here, we determined whether in vitro experimental coevolution can increase the efficiency of phage therapy by limiting the resistance evolution of intermittent and chronic cystic fibrosis Pseudomonas aeruginosa lung isolates to four different phages. We first pre-adapted all phage strains against all bacterial strains and then compared the efficacy of pre-adapted and nonadapted phages against ancestral bacterial strains. We found that evolved phages were more efficient in reducing bacterial densities than ancestral phages. This was primarily because only 50% of bacterial strains were able to evolve resistance to evolved phages, whereas all bacteria were able to evolve some level of resistance to ancestral phages. Although the rate of resistance evolution did not differ between intermittent and chronic isolates, it incurred a relatively higher growth cost for chronic isolates when measured in the absence of phages. This is likely to explain why evolved phages were more effective in reducing the densities of chronic isolates. Our data show that pathogen genotypes respond differently to phage pre-adaptation, and as a result, phage therapies might need to be individually adjusted for different patients.

  2. Response in soil of Cupriavidus necator and other copper-resistant bacterial predators of bacteria to addition of water, soluble nutrients, various bacterial species, or Bacillus thuringiensis spores and crystals

    SciTech Connect

    Casida, L.E. Jr. )

    1988-09-01

    Soil was incubated with various species of bacteria, Bacillus subtilis, or Bacillus thuringiensis spores and crystals. These were added to serve as potential prey for indigenous, copper-resistant, nonobligate bacterial predators of bacteria in the soil. Alternatively, the soil was incubated with soluble nutrients or water only to cause potential indigenous prey cells to multiply so the predator cells would multiply. All of these incubation procedures caused excessive multiplication of some gram-negative bacteria in soil. Even greater multiplication, however, often occurred for certain copper-resistant bacterial predators of bacteria that made up a part of the gram-negative response. Incubation of the soil with copper per se did not give these responses. In most cases, the copper-resistant bacteria that responded were Cupriavidus necator, bacterial predator L-2, or previously unknown bacteria that resembled them. The results suggest that, under various conditions of soil incubation, gram-negative bacterial predators of bacteria multiply and that several copper-resistant types among them can be detected, counted, and isolated by plating dilutions of the soil onto media containing excess copper.

  3. [Mobile ISCR elements: structure, functions, and role in the emergence, increasing and spreading of blocks of bacterial genes of multiple antibiotic resistance].

    PubMed

    Il'ina, T S

    2012-01-01

    The recently discovered method of horizontal distribution of bacterial genes with atypical ISCR sequences is reviewed using an example of drug resistance genes. The adjacent DNA segment mobilization is provided by the transposition of such elements, including rolling circle replication, formation of autonomous nonreplicable circular structures, and homological recombination. The gene distribution capacity with the ISCR elements is more significant than the capacity of transposons and integrons, thereby providing formation of groups of mobile genes, including antibiotic-resistance genes of pathogenic bacteria. The structure and functions of the ISCR elements were discussed together with their similarity and dissimilarity with the group of IS91-similar elements and their role in the emergence of blocks of bacterial genes encoding of multiple antibiotic resistance and their contribution to evolution of bacterial and plasmid genes.

  4. Filtration of a bacterial fermentation broth: harvest conditions effects on cake hydraulic resistance.

    PubMed

    Meireles, M; Lavoute, E; Bacchin, P

    2003-03-01

    The hydraulic resistance of cakes formed during the ultrafiltration of Streptomyces pristinaespiralis broths has been investigated for different harvesting conditions. S. pristinaespiralis broth was harvested after the point of microorganism activity declines (0-h aged broth) and afterwards held for different durations of up to 16 h (16 aged broths). Aging behavior occurring between the end of microorganism activity and harvest was compared for different acidification procedures (pH) and the mechanisms for which the hydraulic resistance of the cake is affected by aging have been investigated. For broths harvested under conditions where the acidification is fixed at pH 2 or 3, hydraulic resistance associated with cake build-up is directly determined by the interactions between the cells. Holding broths beyond 5 h contributes to a release of a soluble component from the cell surface. Enhanced cell surface interactions then turn the cake structure into a more open one and reduce the specific hydraulic resistance. For broths harvested under conditions where the acidification is fixed at pH 4, hydraulic resistance associated with cake build-up is both determined by cell interactions and cell morphology. The cause of the increase in specific hydraulic resistance with aging is due to the binding of a soluble component released by the microorganisms, which decreases the cell surface interactions.

  5. Enhancement of bacterial competitive fitness by apramycin resistance plasmids from non-pathogenic Escherichia coli.

    PubMed

    Yates, C M; Shaw, D J; Roe, A J; Woolhouse, M E J; Amyes, S G B

    2006-09-22

    The study of antibiotic resistance has in the past focused on organisms that are pathogenic to humans or animals. However, the development of resistance in commensal organisms is of concern because of possible transfer of resistance genes to zoonotic pathogens. Conjugative plasmids are genetic elements capable of such transfer and are traditionally thought to engender a fitness burden on host bacteria. In this study, conjugative apramycin resistance plasmids isolated from newborn calves were characterized. Calves were raised on a farm that had not used apramycin or related aminoglycoside antibiotics for at least 20 months prior to sampling. Of three apramycin resistance plasmids, one was capable of transfer at very high rates and two were found to confer fitness advantages on new Escherichia coli hosts. This is the first identification of natural plasmids isolated from commensal organisms that are able to confer a fitness advantage on a new host. This work indicates that reservoirs of antibiotic resistance genes in commensal organisms might not decrease if antibiotic usage is halted.

  6. Steering Evolution with Sequential Therapy to Prevent the Emergence of Bacterial Antibiotic Resistance.

    PubMed

    Nichol, Daniel; Jeavons, Peter; Fletcher, Alexander G; Bonomo, Robert A; Maini, Philip K; Paul, Jerome L; Gatenby, Robert A; Anderson, Alexander R A; Scott, Jacob G

    2015-09-01

    The increasing rate of antibiotic resistance and slowing discovery of novel antibiotic treatments presents a growing threat to public health. Here, we consider a simple model of evolution in asexually reproducing populations which considers adaptation as a biased random walk on a fitness landscape. This model associates the global properties of the fitness landscape with the algebraic properties of a Markov chain transition matrix and allows us to derive general results on the non-commutativity and irreversibility of natural selection as well as antibiotic cycling strategies. Using this formalism, we analyze 15 empirical fitness landscapes of E. coli under selection by different β-lactam antibiotics and demonstrate that the emergence of resistance to a given antibiotic can be either hindered or promoted by different sequences of drug application. Specifically, we demonstrate that the majority, approximately 70%, of sequential drug treatments with 2-4 drugs promote resistance to the final antibiotic. Further, we derive optimal drug application sequences with which we can probabilistically 'steer' the population through genotype space to avoid the emergence of resistance. This suggests a new strategy in the war against antibiotic-resistant organisms: drug sequencing to shepherd evolution through genotype space to states from which resistance cannot emerge and by which to maximize the chance of successful therapy.

  7. Activity of Norspermidine on Bacterial Biofilms of Multidrug-Resistant Clinical Isolates Associated with Persistent Extremity Wound Infections.

    PubMed

    Cardile, Anthony P; Woodbury, Ronald L; Sanchez, Carlos J; Becerra, Sandra C; Garcia, Rebecca A; Mende, Katrin; Wenke, Joseph C; Akers, Kevin S

    2016-11-19

    Biofilm formation is a major virulence factor for numerous pathogenic bacteria and is cited as a central event in the pathogenesis of chronic human infections, which is in large part due to excessive extracellular matrix secretion and metabolic changes that occur within the biofilm rendering them highly tolerant to antimicrobial treatments. Polyamines, including norspermidine, play central roles in bacterial biofilm development, but have also recently been shown to inhibit biofilm formation in select strains of various pathogenic bacteria. The aim of this study was to evaluate in vitro the biofilm dispersive and inhibitory activities of norspermidine against multidrug-resistant clinical isolates of Acinetobacter baumannii(n = 4), Klebsiella pneumoniae (n = 3), Pseudomonas aeruginosa (n = 5) and Staphylococcus aureus (n = 4) associated with chronic extremity wound infections using the semi-quantitative 96-well plate method and confocal laser microscopy. In addition to the antibiofilm activity, biocompatibility of norspermidine was also evaluated by measuring toxicity in vitro to human cell lines and whole porcine tissue explants using MTT viability assay and histological analysis. Norspermidine (5-20 mM) had variable dispersive and inhibitory activity on biofilms which was dependent on both the strain and species. Of the clinical bacterial species evaluated herein, A. baumannii isolates were the most sensitive to the effect of norspermidine, which was in part due to the inhibitory effects of norspermidine on bacterial motility and expression of genes involved in the production of homoserine lactones and quorum sensing molecules both essential for biofilm formation. Importantly, exposure of cell lines and whole tissues to norspermidine for prolonged periods of time (≥24 h) was observed to reduce viability and alter tissue histology in a time and concentration dependent manner, with 20 mM exposure having the greatest negative effects on both

  8. Bioremediation of multi-metal contaminated soil using biosurfactant - a novel approach.

    PubMed

    Juwarkar, Asha A; Dubey, Kirti V; Nair, Anupa; Singh, Sanjeev Kumar

    2008-03-01

    An unconventional nutrient medium, distillery spent wash (1:3) diluted) was used to produce di-rhamnolipid biosurfactant by Pseudomonas aeruginosa strain BS2. This research further assessed the potential of the biosurfactant as a washing agent for metal removal from multimetal contaminated soil (Cr-940 ppm; Pb-900 ppm; Cd-430 ppm; Ni-880 ppm; Cu-480 ppm). Out of the treatments of contaminated soil with tap water and rhamnolipid biosurfactant, the latter was found to be potent in mobilization of metal and decontamination of contaminated soil. Within 36 hours of leaching study, di-rhamnolipid as compared to tap water facilitated 13 folds higher removal of Cr from the heavy metal spiked soil whereas removal of Pb and Cu was 9-10 and 14 folds higher respectively. Leaching of Cd and Ni was 25 folds higher from the spiked soil. This shows that leaching behavior of biosurfactant was different for different metals. The use of wastewater for production of biosurfactant and its efficient use in metal removal make it a strong applicant for bioremediation.

  9. Development and application of a multimetal multibiotic ligand model for assessing aquatic toxicity of metal mixtures.

    PubMed

    Santore, Robert C; Ryan, Adam C

    2015-04-01

    A multimetal, multiple binding site version of the biotic ligand model (mBLM) has been developed for predicting and explaining the bioavailability and toxicity of mixtures of metals to aquatic organisms. The mBLM was constructed by combining information from single-metal BLMs to preserve compatibility between the single-metal and multiple-metal approaches. The toxicities from individual metals were predicted by assuming additivity of the individual responses. Mixture toxicity was predicted based on both dissolved metal and mBLM-normalized bioavailable metal. Comparison of the 2 prediction methods indicates that metal mixtures frequently appear to have greater toxicity than an additive estimation of individual effects on a dissolved metal basis. However, on an mBLM-normalized basis, mixtures of metals appear to be additive or less than additive. This difference results from interactions between metals and ligands in solutions including natural organic matter, processes that are accounted for in the mBLM. As part of the mBLM approach, a technique for considering variability was developed to calculate confidence bounds (called response envelopes) around the central concentration-response relationship. Predictions using the mBLM and response envelope were compared with observed toxicity for a number of invertebrate and fish species. The results show that the mBLM is a useful tool for considering bioavailability when assessing the toxicity of metal mixtures.

  10. [Biotypes and antibiotic resistance patterns of Gardnerella vaginalis strains isolated from healthy women and women with bacterial vaginosis].

    PubMed

    Tosun, Ilknur; Alpay Karaoğlu, Sengül; Ciftçi, Hasan; Buruk, Celal Kurtuluş; Aydin, Faruk; Kiliç, Ali Osman; Ertürk, Murat

    2007-01-01

    As Gardnerella vaginalis is accepted as a member of normal vaginal flora, it is one of the dominant species which has been related to bacterial vaginosis (BV). The aim of this study was to determine the isolation rate, biotypes and antibiotic resistance patterns of G.vaginalis from the vaginal swab samples of 408 women who were admitted to the outpatient clinics of Family Planning Center. Hippurate hydrolysis, lipase and beta-galactosidase tests were performed for biotyping the isolates, and agar dilution (for metronidazole) and disk diffusion (for clindamycin) tests were used for the detection of antibiotic resistance patterns. As a result, by Nugent's BV scoring protocol, 122 (29.9%), 20 (29.4%), 137 (33.6%), and 18 (4.4%) of the women were diagnosed as BV, intermediate form, normal vaginal flora (NVF) and mycotic vaginosis, respectively. The overall isolation rate of G.vaginalis was found as 23% (94/408). Of them, 56.4% (53/94) and 8.5% (8/94) were isolated from samples of BV cases and subjects with NVF, respectively, and the difference was statistically significant (p<0.05). The biotyping results showed that the most frequently detected types were biotype 1 (44%), 5 (20%) and 4 (18%). There was no statistically significant difference between the biotype distribution of BV patients and the subjects who have NVF (p=0.687). The results of antibiotic susceptibility tests indicated that 70% and 53% of the isolates were resistant to metronidazole and clindamycin, respectively. It was of interest that MIC values for metronidazole was > or =128 microg/ml in 57% of resistant strains. The data of this study has emphasized that the metronidazole resistance is very high in our population, and the large scale studies are needed to clarify the relationship between BV and G.vaginalis biotypes, which can be found in the normal vaginal flora.

  11. Improvement of Basmati rice varieties for resistance to blast and bacterial blight diseases using marker assisted backcross breeding.

    PubMed

    Ellur, Ranjith K; Khanna, Apurva; Yadav, Ashutosh; Pathania, Sandeep; Rajashekara, H; Singh, Vikas K; Gopala Krishnan, S; Bhowmick, Prolay K; Nagarajan, M; Vinod, K K; Prakash, G; Mondal, Kalyan K; Singh, Nagendra K; Vinod Prabhu, K; Singh, Ashok K

    2016-01-01

    Marker assisted backcross breeding was employed to incorporate the blast resistance genes, Pi2 and Pi54 and bacterial blight (BB) resistance genes xa13 and Xa21 into the genetic background of Pusa Basmati 1121 (PB1121) and Pusa Basmati 6. Foreground selection for target gene(s) was followed by arduous phenotypic and background selection which fast-tracked the recovery of recurrent parent genome (RPG) to an extent of 95.8% in one of the near-isogenic lines (NILs) namely, Pusa 1728-23-33-31-56, which also showed high degree of resemblance to recurrent parent, PB6 in phenotype. The phenotypic selection prior to background selection provided an additional opportunity for identifying the novel recombinants viz., Pusa 1884-9-12-14 and Pusa 1884-3-9-175, superior to parental lines in terms of early maturity, higher yield and improved quality parameters. There was no significant difference between the RPG recovery estimated based on SSR or SNP markers, however, the panel of SNPs markers was considered as the better choice for background selection as it provided better genome coverage and included SNPs in the genic regions. Multi-location evaluation of NILs depicted their stable and high mean performance in comparison to the respective recurrent parents. The Pi2+Pi54 carrying NILs were effective in combating a pan-India panel of Magnaporthe oryzae isolates with high level of field resistance in northern, eastern and southern parts of India. Alongside, the PB1121-NILs and PB6-NILs carrying BB resistance genes xa13+Xa21 were resistant against Xanthomonas oryzae pv. oryzae races of north-western, southern and eastern parts of the country. Three of NILs developed in this study, have been promoted to final stage of testing during the ​Kharif 2015 in the Indian National Basmati Trial.