title: In vivo sequential selection of Escherichia coli with topoisomerase- and efflux-mediated misleading quinolone resistance phenotypes.
abstract: Two mutants of Escherichia coli (V1 and V2) with acquired mechanisms of resistance to fluoroquinolones were isolated sequentially from blood cultures of a patient with cholangiocarcinoma treated repeatedly with ofloxacin; a third mutant (V3) was isolated under ciprofloxacin therapy. All mutants were related clonally. V1 was susceptible to quinolones but with diminished susceptibility to ofloxacin. V2 was hypersusceptible to nalidixic acid but had high-level resistance to ofloxacin. V3 was resistant to all quinolones. Ofloxacin selected for original gyrA and parC mutations, leading to the unusual and misleading resistance phenotypes of V1 and V2, whereas efflux played a major role in the increased resistance of V3.
authors: Service de Bactériologie, Hôpital Avicenne, APHP, Bobigny and Université Paris, Bobigny, France.
authors: Mounira
authors: M
authors: Smati
authors: Jean-Philippe
authors: JP
authors: Emond
authors: Guillaume
authors: G
authors: Arlet
authors: Jacques
authors: J
authors: Tankovic
mesh_terms: D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D015373:Bacterial Typing Techniques; D002939:Ciprofloxacin / Q000494:pharmacology; D027081:DNA Gyrase / Q000235:genetics*; D004264:DNA Topoisomerases, Type I / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009268:Nalidixic Acid / Q000494:pharmacology; D015242:Ofloxacin / Q000494:pharmacology; D010641:Phenotype; D015363:Quinolones / Q000494:pharmacology; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015363:Quinolones; D009268:Nalidixic Acid; D002939:Ciprofloxacin; D015242:Ofloxacin; D004264:DNA Topoisomerases, Type I; D027081:DNA Gyrase