title: Characterization of gyrA, gyrB, grlA and grlB mutations in fluoroquinolone-resistant clinical isolates of Staphylococcus aureus.
abstract: The distribution of fluoroquinolone resistance-associated point mutations in genes encoding the subunits of DNA gyrase and DNA topoisomerase i.v. was examined in 110 clinical isolates of Staphylococcus aureus. Point mutations were detected by polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis and mutations were further characterized by sequencing of PCR products. Mutations at Ser84 of GyrA were widely distributed among isolates exhibiting various degrees of fluoroquinolone resistance, and border zones between mutant and non-mutant strains based on drug susceptibility were generally distinct. Mutations at Ser80 of GrlA were also widely distributed, but border zones between mutant and non-mutant isolates were in this case less distinct and several GrlA mutants were highly susceptible to sparfloxacin and tosufloxacin. Only two gyrB mutants and one grlB mutant were observed among the isolates: all contained a previously unreported mutation. GyrA and grlA mutations thus appear to impart high levels of fluoroquinolone resistance in many S. aureus clinical isolates.
authors.affiliation: Department of Respiratory Oncology and Molecular Medicine, Tohoku University, Miyagi, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
authors.forename: T
authors.initials: T
authors.lastname: Kikuchi
authors.forename: S
authors.initials: S
authors.lastname: Shoji
authors.forename: S
authors.initials: S
authors.lastname: Fujimura
authors.forename: A B
authors.initials: AB
authors.lastname: Lutfor
authors.forename: Y
authors.initials: Y
authors.lastname: Tokue
authors.forename: T
authors.initials: T
authors.lastname: Nukiwa
authors.forename: A
authors.initials: A
authors.lastname: Watanabe
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D027101:DNA Topoisomerase IV; D004250:DNA Topoisomerases, Type II / Q000235:genetics*; D004148:Dioxolanes / Q000494:pharmacology; D004352:Drug Resistance, Microbial / Q000235:genetics; D024841:Fluoroquinolones; D005798:Genes, Bacterial / Q000235:genetics*; D006801:Humans; D010879:Piperazines / Q000494:pharmacology; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D015363:Quinolones / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*
chemical_list: D000890:Anti-Infective Agents; D004148:Dioxolanes; D024841:Fluoroquinolones; D010879:Piperazines; D015363:Quinolones; D027101:DNA Topoisomerase IV; D004250:DNA Topoisomerases, Type II; C074191:prulifloxacin; C077155:balofloxacin