title: In vitro selected fluoroquinolone-resistant mutants of Citrobacter freundii: analysis of the quinolone resistance acquisition.
abstract: Ten quinolone-resistant mutants of Citrobacter freundii, which were selected in vitro with fluoroquinolones from two clinical isolates, were studied. The parent isolates were susceptible to quinolones in spite of showing a single substitution in the GyrB (His-417 --> Leu). No change was observed in the outer membrane proteins or in the lipopolysaccharide in any of the ten mutants studied with respect to their parent isolates. The development of quinolone resistance in selected mutants was associated with the appearance of a substitution in the GyrA (Thr-83 --> Ile) in nine of the ten mutants plus enhanced active efflux in all of them.
authors.affiliation: Microbiology, Department of Clinical Sciences, School of Medicine, University of Las Palmas de Gran Canaria. mtavio@infovia.ulpgc.es
authors.forename: M
authors.initials: M
authors.lastname: Tavío
authors.forename: J
authors.initials: J
authors.lastname: Vila
authors.forename: J
authors.initials: J
authors.lastname: Ruiz
authors.forename: G
authors.initials: G
authors.lastname: Amicosante
authors.forename: N
authors.initials: N
authors.lastname: Franceschini
authors.forename: A M
authors.initials: AM
authors.lastname: Martín-Sánchez
authors.forename: M T
authors.initials: MT
authors.lastname: de Anta
mesh_terms: D000890:Anti-Infective Agents / Q000378:metabolism / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000187:drug effects; D016971:Citrobacter freundii / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D004352:Drug Resistance, Microbial; D008070:Lipopolysaccharides / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics; D009643:Norfloxacin / Q000378:metabolism / Q000494:pharmacology; D010641:Phenotype
chemical_list: D000890:Anti-Infective Agents; D001425:Bacterial Outer Membrane Proteins; D008070:Lipopolysaccharides; D009643:Norfloxacin