gyrA和parC介导的铜绿假单胞菌对环丙沙星耐药机制研究

Mechanism of gyrA and parC mediated ciprofloxacin resistance in pseudomonas aeruginosa

目的了解十堰地区耐氟喹诺酮类铜绿假单胞菌(PA)的药敏情况及gyrA和parC基因突变情况。方法用Vitek32对110株PA进行鉴定和药敏检测,对临床常用抗生素的药敏情况进行分析,琼脂稀释法测定60株耐环丙沙星(CIP)的PA对CIP的最低抑菌浓度(MIC),限制性长度多态性分析法(PCR-RFLP)检测耐CIP的PAgyrA和parC基因突变情况。结果耐药菌株对哌拉西林/他唑巴坦的敏感率最高(68.3%)。在60株耐CIP的PA中有42株(70.0%)耐药菌株发生gyrA基因的83位点突变,密码子发生ACC→ATC改变,编码83位氨基酸的碱基发生突变Thr→Ile(ACC→ATC),有38株(63.3%)耐药菌株发生parC基因87位点突变Ser→Leu(TCG→TTG),同时发生两种突变的共36株(60.0%)。结论耐氟喹诺酮类PA对临床常用抗生素的敏感性降低,并呈多重耐药,药物作用靶位gyrA和parC的基因突变为其耐氟喹诺酮类药物的主要机制。

Objective To explore the drug sensitivity and the gyrA and parC gene mutation of quinolone-resistant Pseudomonas aeruginosa （PA） in Shiyan district. Methods Identification and the drug resistance of 110 strains PA were performed and detected by Vitek 32 system. Agar dilution and PCR-RFLP were used to detect the minimum inhibitory concentrations （MIC） of PA to cip- rofloxacin（CIP） and the mutation of gyrA and parC in 60 CIP resistant PA strains,respectively. Results CIP resistant PA strains were most sensitive to piperacillin/tazobactam （68.3 %）. Among the 60 CIP resistant PA strains,C83T mutation in gyrA gene,inducing Thr→Ile amino acid mutation,were detected in 42 CIP resistant PA strains（70.0%） and C87T mutation in parC gene,indu cing Ser→Leu mutation,were detected in 42（70.0%） and 38（63.3%） strains,respectively,and the two mutations were both detected in 36（60.0%） strains. Conclusion The sensitivity of quinolones resistant PA to common clinically used antibiotics have been decreased, with multi-drug resistance detected. The mechanism of fluoroquinolones resistance of PA could be due to the mutaions of gyrA and parC gene,encoding the target sites of fluoroquinolones.