Examination of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus Mutants with Low-Level Fluoroquinolone Resistance

For Staphylococcus aureus, stepwise mutations result in high-level quinolone resistance. Methicillin-resistant and -susceptible quinolone-resistant, first-step mutants generated in vitro were obtained and found to be no different than those recovered from murine abscesses. Approximately 10% of all first-step mutants were resistant to ethidium bromide, and selected strains had mutations that mapped to flqB. NorA-mediated resistance among first-step mutants may be more prevalent than previously reported.

针对金黄色葡萄球菌（Staphylococcus aureus），逐步突变可使其产生高水平喹诺酮耐药性（quinolone resistance）。本研究成功获取了体外（in vitro）构建的喹诺酮耐药第一步突变体，该类突变体涵盖耐甲氧西林与甲氧西林敏感两种表型；经比对验证，其与从小鼠脓肿中分离得到的对应突变体无显著差异。约10%的第一步突变体对溴化乙锭（ethidium bromide）具有耐药性，经筛选获得的菌株携带定位在flqB基因上的突变。第一步突变体中由NorA介导的耐药性可能比此前文献报道的更为普遍。