title: Resistance to multiple fluoroquinolones in a clinical isolate of Streptococcus pyogenes: identification of gyrA and parC and specification of point mutations associated with resistance.
abstract: A strain of Streptococcus pyogenes resistant to multiple fluoroquinolones was isolated from the blood of an immunocompromised patient. Resistance to fluoroquinolones in S. pyogenes has not been previously studied. Compared to 10 sensitive strains of S. pyogenes, the fluoroquinolone-resistant clinical isolate of S. pyogenes presented point mutations in gyrA, predicting that serine-81 was changed to phenylalanine and that methionine-99 was changed to leucine, and in parC, predicting that serine-79 was changed to tyrosine. The mechanism of fluoroquinolone resistance in this isolate of S. pyogenes appears to be analogous to previously reported mechanisms for Streptococcus pneumoniae.
authors.affiliation: Microbiology Service, CPD, Clinical Center, National Institutes of Health, Bethesda, Maryland 20892-1508, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Yan
authors.forename: M L
authors.initials: ML
authors.lastname: Fox
authors.forename: S M
authors.initials: SM
authors.lastname: Holland
authors.forename: F
authors.initials: F
authors.lastname: Stock
authors.forename: V J
authors.initials: VJ
authors.lastname: Gill
authors.forename: D P
authors.initials: DP
authors.lastname: Fedorko
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D027081:DNA Gyrase; D027101:DNA Topoisomerase IV; D004250:DNA Topoisomerases, Type II / Q000235:genetics*; D004352:Drug Resistance, Microbial / Q000235:genetics; D018432:Drug Resistance, Multiple / Q000235:genetics*; D024841:Fluoroquinolones; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D017354:Point Mutation; D013297:Streptococcus pyogenes / Q000187:drug effects / Q000235:genetics*
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II