title: In-vitro mutagenesis of qnrA and qnrS genes and quinolone resistance in Escherichia coli.
abstract: Plasmid-mediated quinolone resistance is being reported increasingly worldwide among isolates of enterobacteria. This resistance is mostly associated with Qnr-like determinants that confer resistance to quinolones, e.g., nalidixic acid, and reduced susceptibility to fluoroquinolones. This study investigated whether amino-acid substitutions in QnrA1 and QnrS1 determinants might be responsible for an enhancement of resistance to quinolones and, particularly, to fluoroquinolones. However, random and site-directed mutagenesis failed to identify any single amino-acid substitution that could be responsible for higher levels of resistance to quinolones or fluoroquinolones, indicating that the selection of such mutants in vivo is probably a rare event.
authors.affiliation: Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, Université Paris XI, France.
authors.forename: V
authors.initials: V
authors.lastname: Cattoir
authors.forename: L
authors.initials: L
authors.lastname: Poirel
authors.forename: P
authors.initials: P
authors.lastname: Nordmann
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D016296:Mutagenesis; D010957:Plasmids / Q000235:genetics; D015363:Quinolones / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D015363:Quinolones