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Author (up) Aarestrup, F.M.; Bager, F.; Jensen, N.E.; Madsen, M.; Meyling, A.; Wegener, H.C. file  url
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  Title Surveillance of antimicrobial resistance in bacteria isolated from food animals to antimicrobial growth promoters and related therapeutic agents in Denmark Type Journal Article
  Year 1998 Publication APMIS : Acta Pathologica, Microbiologica, et Immunologica Scandinavica Abbreviated Journal Apmis  
  Volume 106 Issue 6 Pages 606-622  
  Keywords Animals; Anti-Bacterial Agents/*pharmacology; Bacteria/*drug effects/*isolation & purification; Bacterial Infections/drug therapy/veterinary; Cattle; Cattle Diseases/drug therapy/microbiology; Cecum/microbiology; Chickens/growth & development; Drug Resistance, Microbial; Feces/microbiology; Meat/*microbiology; Microbial Sensitivity Tests/veterinary; Poultry Diseases/drug therapy/microbiology; Swine/growth & development; Swine Diseases/drug therapy/microbiology  
  Abstract This study was conducted to describe the occurrence of acquired resistance to antimicrobials used for growth promotion among bacteria isolated from swine, cattle and poultry in Denmark. Resistance to structurally related therapeutic agents was also examined. Three categories of bacteria were tested: 1) indicator bacteria (Escherichia coli, Enterococcus faecalis, Enterococcus faecium), 2) zoonotic bacteria (Campylobacter, Salmonella, Yersinia enterocolitica), and 3) animal pathogens (E. coli, Staphylococcus aureus, coagulase-negative staphylococci (CNS), Staphylococcus hyicus, Actinobacillus pleuropneumoniae). All antimicrobials used as growth promoters in Denmark and some structurally related therapeutic agents (in brackets) were included: Avilamycin, avoparcin (vancomycin), bacitracin, carbadox, flavomycin, monensin, olaquindox, salinomycin, spiramycin (erythromycin, lincomycin), tylosin (erythromycin, lincomycin), and virginiamycin (pristinamycin). Bacterial species intrinsically resistant to an antimicrobial were not tested towards that antimicrobial. Breakpoints for growth promoters were established by population distribution of the bacteria tested. A total of 2,372 bacterial isolates collected during October 1995 to September 1996 were included in the study. Acquired resistance to all currently used growth promoting antimicrobials was found. A frequent occurrence of resistance were observed to avilamycin, avoparcin, bacitracin, flavomycin, spiramycin, tylosin and virginiamycin, whereas resistance to carbadox, monensin, olaquindox and salinomycin was less frequent. The occurrence of resistance varied by animal origin and bacterial species. The highest levels of resistance was observed among enterococci, whereas less resistance was observed among zoonotic bacteria and bacteria pathogenic to animals. The association between the occurrence of resistance and the consumption of the antimicrobial is discussed. The results show the present level of resistance to growth promoters in bacteria from food animals in Denmark. They will form the baseline for comparison with future prospective studies, thereby enabling the determination of trends over time.  
  Call Number Serial 1676  
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Author (up) Cundliffe, E.; McQuillen, K. file  url
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  Title Bacterial protein synthesis: the effects of antibiotics Type Journal Article
  Year 1967 Publication Journal of Molecular Biology Abbreviated Journal J Mol Biol  
  Volume 30 Issue 1 Pages 137-146  
  Keywords Amino Acids/metabolism; Anti-Bacterial Agents/*pharmacology; Bacillus megaterium/*drug effects/metabolism; Bacterial Proteins/*biosynthesis; Carbon Isotopes; Centrifugation, Density Gradient; Chloramphenicol/pharmacology; Chlortetracycline/*pharmacology; Deoxyribonucleases/pharmacology; Erythromycin/pharmacology; Peptides/metabolism; Phosphates/metabolism; Phosphorus Isotopes; Protoplasts/metabolism; Puromycin/*pharmacology; Ribonucleases/pharmacology; Ribosomes/drug effects/metabolism  
  Abstract Puromycin induced the release of nascent peptides from ribosomes. We have studied this effect in vivo using protoplasts of Bacillus megaterium. Chloramphenicol, erythromycin and sparsomycin inhibited the reaction, but chlortetracycline, bottromycin and pactamycin did not.

In the presence of chlortetracycline, both chloramphenicol and sparsomycin completely inhibited the puromycin reaction, whereas erythromycin allowed release of much of the nascent peptide.

We suggest that chloramphenicol and sparsomycin inhibit the peptidyl transferase reaction, and that erythromycin may inhibit the translocation reaction(s).
 
  Call Number Serial 531  
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Author (up) Firsov, A.A.; Strukova, E.N.; Portnoy, Y.A.; Shlykova, D.S.; Zinner, S.H. file  url
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  Title Bacterial antibiotic resistance studies using in vitro dynamic models: Population analysis vs. susceptibility testing as endpoints of mutant enrichment Type Journal Article
  Year 2015 Publication International Journal of Antimicrobial Agents Abbreviated Journal Int J Antimicrob Agents  
  Volume 46 Issue 3 Pages 313-318  
  Keywords Anti-Bacterial Agents/*pharmacology; Ciprofloxacin/*pharmacology; *Drug Resistance, Bacterial; Humans; Microbial Sensitivity Tests; Models, Theoretical; Mutation; Pseudomonas Infections/microbiology; Pseudomonas aeruginosa/*drug effects/*growth & development/isolation & purification; *Selection, Genetic; Time Factors; Bacterial resistance studies; Fluoroquinolones; Population analysis; Pseudomonas aeruginosa; Susceptibility testing  
  Abstract 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 2x, 4x, 8x and 16x 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.  
  Call Number Serial 1214  
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Author (up) Heuer, H.; Schmitt, H.; Smalla, K. file  url
openurl 
  Title Antibiotic resistance gene spread due to manure application on agricultural fields Type Journal Article
  Year 2011 Publication Current Opinion in Microbiology Abbreviated Journal Curr Opin Microbiol  
  Volume 14 Issue 3 Pages 236-243  
  Keywords Agriculture/*methods; Animals; Anti-Bacterial Agents/*pharmacology; Bacteria/*drug effects/*genetics; *Drug Resistance, Bacterial; Gene Transfer, Horizontal; Humans; Interspersed Repetitive Sequences; Manure/*microbiology; Selection, Genetic  
  Abstract The usage of antibiotics in animal husbandry has promoted the development and abundance of antibiotic resistance in farm environments. Manure has become a reservoir of resistant bacteria and antibiotic compounds, and its application to agricultural soils is assumed to significantly increase antibiotic resistance genes and selection of resistant bacterial populations in soil. The genome location of resistance genes is likely to shift towards mobile genetic elements such as broad-host-range plasmids, integrons, and transposable elements. Horizontal transfer of these elements to bacteria adapted to soil or other habitats supports their environmental transmission independent of the original host. The human exposure to soil-borne resistance has yet to be determined, but is likely to be severely underestimated.  
  Call Number Serial 1955  
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Author (up) Kim, T.; Bak, G.; Lee, J.; Kim, K.-S. file  url
openurl 
  Title Systematic analysis of the role of bacterial Hfq-interacting sRNAs in the response to antibiotics Type Journal Article
  Year 2015 Publication The Journal of Antimicrobial Chemotherapy Abbreviated Journal J Antimicrob Chemother  
  Volume 70 Issue 6 Pages 1659-1668  
  Keywords Adaptation, Physiological; Anti-Bacterial Agents/*pharmacology; Escherichia coli/*drug effects/genetics/growth & development; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Gene Knockout Techniques; Host Factor 1 Protein/genetics/*metabolism; Humans; Microbial Sensitivity Tests; Microbial Viability/drug effects; RNA, Small Untranslated/genetics/*metabolism; Salmonella/*drug effects/genetics/growth & development; Stress, Physiological; Hfq protein; multidrug resistance; small non-coding RNA; species conservation  
  Abstract OBJECTIVES: To systematically analyse the interplay between the expression of Hfq-associated small non-coding RNAs (sRNAs) and antibiotic susceptibility in Gram-negative bacteria. METHODS: To identify the roles of sRNAs in the antibiotic susceptibility of Escherichia coli and Salmonella species, susceptibility tests, growth analyses and viability assays were performed using E. coli Hfq-associated sRNAs from overexpression libraries. Prediction, susceptibility testing of gene knockouts and expression analysis of target genes under conditions of sRNA overexpression or knockout were performed to identify candidate targets for modulating antibiotic susceptibility. RESULTS: The susceptibilities of E. coli strains overexpressing each of the 26 known Hfq-dependent sRNAs to major classes of antibiotics were determined. Induced expression of 17 sRNAs modulated the susceptibility of E. coli to antibiotics. Among them, four sRNA knockout strains partially or completely reversed susceptibility phenotypes of sRNA overexpression. The phenotype of OxyS, RseX or MicF was not entirely dependent on the presence of Hfq protein, in contrast to the dependency of previously characterized roles. The function of eight of nine sRNAs was found to be conserved in the response to antibiotics in Salmonella. Some MicF- or RyeB-mediated cellular target genes and pathways that may be important for the regulation of antibiotic susceptibility were identified. Finally, the overexpression of RyeB potentiated the efficacy of levofloxacin against MDR strains. CONCLUSIONS: Our data indicate that Hfq-associated sRNAs potentially enable bacteria to adapt to antibiotic challenges via multifaceted approaches. Therefore, sRNA-based applications will form a new antibiotic arsenal for combating the rise in antibiotic resistance.  
  Call Number Serial 1588  
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