title: Relationships between mutant prevention concentrations and mutation frequencies against enrofloxacin for avian pathogenic Escherichia coli isolates.
abstract: Clinical efficacies of mutant prevention concentration (MPC) and mutant selection window (MSW) hypotheses have been evaluated for human clinical isolates. We tested the MSW hypothesis by evaluating the relationships between MPCs and mutation frequencies against enrofloxacin for avian pathogenic Escherichia coli (APEC) isolates. Mutation frequencies of strains with MPC:MIC ratios of 8 to 16 were significantly higher than those of strains with an MPC:MIC ratio of 4. Mutation frequencies and MPCs of serogroup O2 strains were lower than those of the other strains; these results may correlate with the absence of fluoroquinolone-resistant O2 strains. Our results support the MSW hypothesis that the range of the MSW is involved in selection of resistant mutants.
authors: National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan. ozawa@nval.maff.go.jp
authors: Manao
authors: M
authors: Ozawa
authors: Tetsuo
authors: T
authors: Asai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002645:Chickens; D027081:DNA Gyrase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D027101:DNA Topoisomerase IV / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D000077422:Enrofloxacin; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D024841:Fluoroquinolones / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D007564:Japan / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D009154:Mutation; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology; D012641:Selection, Genetic
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D024841:Fluoroquinolones; D000077422:Enrofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase