title: In vitro effect of qnrA1, qnrB1, and qnrS1 genes on fluoroquinolone activity against isogenic Escherichia coli isolates with mutations in gyrA and parC.
abstract: This article provides an analysis of the in vitro effect of qnrA1, qnrB1, and qnrS1 genes, combined with quinolone-resistant Ser83Leu substitutions in GyrA and/or Ser80Arg in ParC, on fluoroquinolone (FQ) resistance in isogenic Escherichia coli strains. The association of Ser83Leu substitution in GyrA, Ser80Arg substitution in ParC, and qnr gene expression increased the MIC of ciprofloxacin to 2 μg/ml. qnr genes present in E. coli that harbored a Ser83Leu substitution in GyrA increased mutant prevention concentration (MPC) values to 8 to 32 μg/ml. qnr gene expression in E. coli may play an important role in selecting for one-step FQ-resistant mutants.
authors.affiliation: Department of Microbiology, University of Seville, Seville, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Briales
authors.forename: J M
authors.initials: JM
authors.lastname: Rodríguez-Martínez
authors.forename: C
authors.initials: C
authors.lastname: Velasco
authors.forename: P
authors.initials: P
authors.lastname: Díaz de Alba
authors.forename: J
authors.initials: J
authors.lastname: Domínguez-Herrera
authors.forename: J
authors.initials: J
authors.lastname: Pachón
authors.forename: A
authors.initials: A
authors.lastname: Pascual
mesh_terms: D002939:Ciprofloxacin / Q000494:pharmacology; D027081:DNA Gyrase / Q000235:genetics*; D027101:DNA Topoisomerase IV / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D024841:Fluoroquinolones / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009154:Mutation
chemical_list: D029968:Escherichia coli Proteins; D024841:Fluoroquinolones; D002939:Ciprofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase