耐环丙沙星鲍曼不动杆菌gyrA和parC突变模式分析

Mutation patterns in gyrA and parC genes of ciprofloxacin-resistant strains of Acinetobacter baumannii

目的对临床耐环丙沙星的鲍曼不动杆菌进行gyrA和parC基因突变模式的分子流行病学调查。方法采用E-test法测定环丙沙星对94株临床分离鲍曼不动杆菌的最低抑菌浓度(MIC);对鲍曼不动杆菌的gyrA和parC基因进行聚合酶链反应(PCR)-限制性内切酶片段长度多态性(RFLP)分析及DNA测序。结果在94株鲍曼不动杆菌中,只有38株(40.43%)对环丙沙星敏感(MIC≤1mg/L),而对环丙沙星的耐药率接近60%;PCR-RFLP分析结果表明,对环丙沙星耐药的56株菌都发生了gyrA和parC基因突变,且parC基因的突变率(87.50%)略高于gyrA基因(82.14%)。结论鲍曼不动杆菌对环丙沙星的耐药与gyrA和parC基因突变相关,其中parC基因突变的明显增长值得重视。

Objective To evaluate epidemiology of mutations in the gyrA and parC genes leading to possible increase in ciprofloxacin resistance in clinical isolates of Acinetobacter baumannii. Methods Minimum inhibitory concentration （MIC） of ciprofloxacin to 94 clinical isolates of Acinetobacter baumannii were detected with the Etest method, gyrA and parC genes of these isolates were analysed by PCR-RFLP analysis and DNA sequence. Results Out of the 94 clinical isolates tested, only 38 （40. 43%） strains were found to be susceptible to ciprofloxacin （MIC 41 mg/L）, the resistant rate of these isolates against ciprofloxacin was near 60%. PCR-RFLP analysis revealed that 56 ciprofloxacin-resistant strains had mutation in gyrA and parC genes, the mutation rate of parC gene（87. 50%） was slightly higher than that of gyrA gene（82. 14%）. Conclusion Resistant to ciprofloxacin of Acinetobacter baumannii is related with the mutations in the gyrA and parC genes, the increase of the mutation in the parC should be paid attention.