title: Amino acid substitutions in GyrA and ParC are associated with fluoroquinolone resistance in Mycoplasma bovis isolates from Japanese dairy calves.
abstract: We investigated the contribution of quinolone resistance-determining region (QRDR) mutations to fluoroquinolone (enrofloxacin, orbifloxacin and danofloxacin) susceptibility in 58 Mycoplasma bovis isolates from dairy cattle in Japan. Fluoroquinolone non-resistant isolates (fluoroquinolone-MICs≤2 μg/ml) possessed no QRDR mutations (19 isolates) or Ser83Leu in GyrA (32 isolates). Fluoroquinolone-resistant isolates (fluoroquinolone-MICs≥4 μg/ml) possessed Ser83Leu in GyrA and Ser81Pro in ParC (3 isolates) or Ser83Phe in GyrA and Ser80Ile in ParC (4 isolates). Laboratory-derived fluoroquinolone-resistant mutants selected from 2 isolates (possessing Ser83Leu in GyrA) had an amino acid substitution in ParC at the same position (Ser80Ile or Ser81Tyr) as fluoroquinolone-resistant isolates, suggesting a concurrent amino acid substitution in ParC (Ser80 or Ser81) is important in fluoroquinolone resistance in M. bovis isolates.
authors.affiliation: Laboratory of Food Microbiology and Food Safety, Department of Health and Environmental Sciences, School of Veterinary Medicine, Rakuno Gakuen University, 582 Bunkyoudai-Midorimachi, Ebetsu, Hokkaido 069-8501, Japan.
authors.forename: Toyotaka
authors.initials: T
authors.lastname: Sato
authors.forename: Torahiko
authors.initials: T
authors.lastname: Okubo
authors.forename: Masaru
authors.initials: M
authors.lastname: Usui
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Higuchi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tamura
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000382:microbiology; D027081:DNA Gyrase / Q000235:genetics*; D027101:DNA Topoisomerase IV / Q000235:genetics*; D025141:Drug Resistance, Fungal / Q000235:genetics*; D024841:Fluoroquinolones / Q000494:pharmacology*; D007564:Japan; D008826:Microbial Sensitivity Tests; D009175:Mycoplasma Infections / Q000188:drug therapy / Q000662:veterinary*; D045682:Mycoplasma bovis / Q000187:drug effects / Q000235:genetics*
chemical_list: D024841:Fluoroquinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase