title: Polymorphic mutation frequencies in clinical isolates of Staphylococcus aureus: the role of weak mutators in the development of fluoroquinolone resistance.
abstract: The polymorphic mutation frequencies for 154 Staphylococcus aureus isolates from Chinese bovine clinical mastitis cases were investigated. We found that nearly 29% of the isolates presented as weak mutators, while only two (1.3%) strong mutators were detected. Of the 15 weak mutators that exhibited ciprofloxacin resistance phenotypes, only one isolate was found to be mutS deficient. All of the ciprofloxacin-resistant isolates had the classic ciprofloxacin resistance mutations at codon 80 within the ParC subunit of topoisomerase IV and codon 84/88 within the GyrA subunit of DNA gyrase. The proportion of ciprofloxacin-resistant isolates among the weak mutators (34.1%) was significantly higher than that found in the normomutators (11.4%) and hypomutators (0%) (P < 0.001, Fisher's exact test), suggesting a positive correlation between weak mutators and ciprofloxacin resistance.
authors: Beijing Key Laboratory of Detection Technology for Animal-Derived Food Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors: Shaochen
authors: S
authors: Wang
authors: Yang
authors: Y
authors: Wang
authors: Jianzhong
authors: J
authors: Shen
authors: Yongning
authors: Y
authors: Wu
authors: Congming
authors: C
authors: Wu
mesh_terms: D000818:Animals; D002417:Cattle; D002939:Ciprofloxacin / Q000494:pharmacology*; D027081:DNA Gyrase / Q000235:genetics; D053843:DNA Mismatch Repair; D027101:DNA Topoisomerase IV / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005260:Female; D005798:Genes, Bacterial; D008414:Mastitis, Bovine / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D059645:Mutation Rate; D012293:Rifampin / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D004269:DNA, Bacterial; D002939:Ciprofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; D012293:Rifampin