季铵盐诱导肺炎克雷伯菌外排泵AcrAB-TolC高表达与喹诺酮耐药关系的研究

Relationship between the high expression of efflux pump AcrAB-TolC induced by quaternary ammonium compound and the resistance of quinolones in K.pneumoniae

目的探讨肺炎克雷伯菌(Kpn) Acr AB-Tol C外排泵参与季铵盐和喹诺酮类抗生素交叉耐药的机制。方法微量稀释法检测苯扎溴铵诱导前后Kpn临床菌株对苯扎溴铵和环丙沙星(CIP)的最低抑菌浓度(MICs);荧光定量RTPCR技术检测诱导菌株和母株外排泵基因acr AB的mRNA的转录水平。结果经苯扎溴铵诱导16株临床菌株对其MICs值提高了2倍~8倍;8株CIP敏感株诱导后5株仍敏感、1株对CIP的MIC=2 mg/L为中介耐药株、2株MIC分别为8 mg/L和16 mg/L成为CIP耐药株;8株CIP耐药株苯扎溴铵诱导后对CIP的MICs提高2倍~8倍。诱导株acr AB基因相对表达量明显高于母株(P <0. 05)。结论 Acr AB-Tol C外排泵表达与季铵盐和喹诺酮类抗生素交叉耐药有一定的相关性。

Objective To investigate the mechanism of efflux pump AcrAB-TolC involved in the cross-resistance between quaternary ammonium compounds and quinolones in K.pneumonia(Kpn).Methods The minimum inhibitory concentrations(MICs)of benzalkonium bromide and ciprofloxacin(CIP)in Kpnisolates which were induced before and after benzalkonium bromide were detected by microdilution method.The efflux pump gene acrAB at mRNA level in the induced isolates and their parent isolates were detected by quantitative real-time PCR.Results The MICs of all Kpn isolates induced by benzalkonium bromide increased by 2-8 times.In 8 CIP sensitive isolates,5 isolates were still CIP sensitive,1 strain mediated and 2 strains resistant after benzalkonium bromide induction;the MICs of CIP in 8 resistant strains increased by 2-8 times.Compared with the parent isolates,the induced Kpn isolates showed higher expression of acrAB gene,and the differences between the two groups were statistically significant(P<0.05).Conclusion It was speculated that the increased expression of efflux pump AcrAB-TolC level in the induced Kpn isolates were related to the cross-resistance between quaternary ammonium compounds and quinolone antibiotics.