CIP耐药的铜绿假单胞菌两种分子耐药机制关系的研究

Study on the relationship of gyrA and parC gene mutation and pump efflux in Pseudomonas aeruginosa clinical isolates of ciprofloxacin resistance

目的探讨环丙沙星(CIP)耐药的铜绿假单胞菌临床分离株主动外排药物与gyrA、parC基因突变的关系。方法联合碳酰氰基-对-氯苯腙(CCCP)和CIP对CIP耐药的铜绿假单胞菌株进行主动外排阳性株和阴性株的筛选,并对这些菌株的gyrA、parC基因进行聚合酶链式反应-限制性片段长度多态性分析(PCR-RFLP)。结果57%(55/97)的CIP耐药菌株最小抑菌浓度(MIC)可被逆转,gyrA单基因突变率为65%,gyrA和parC双基因突变率为35%,未发现parC单基因突变的菌株。主动外排阳性组与阴性组gyrA、parC基因突变情况差异无显著性。结论在本地区铜绿假单胞菌对CIP的耐药机制中,主动外排系统表达上调与抗菌药物作用靶位的改变均占有重要的地位,两者可能是并存的两种相对独立的机制。

Objective To study the relationship ofgyrA andparC gene mutation and pump effiux in Pseudomonas aeruginosa clinical isolates of ciprofloxacin resistance. Methods The dilution method was used to determine minimum inhibitory concentration（MIC） with or without the effiux pump inhibitor Carbonyl Cyarude-3-chlorophcnylhydrazone（CCCP）. Polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） was used to detect the mutation of gyrA and parC. Results. The MIC of 57% （55/97） ciprofloxacin-resistant strains could be significantly reduced by CCCP. The rate of gyrA single gene mutation was 65% ,while the rate of gyrA and parC double gene mutation was 35%. No single gene mutation of parC could be found in the test. There was no statistics difference in gyrA or parC gene mutation between the strains with or without effiux pump. Conclusion In ciprofloxacin resistance mechanism of P. aeruginosa clinical isolates, both gyrA and parC gene mutation and pump effiux play very important roles ,but might function independently.