AcrAB外排泵ramA对肺炎克雷伯菌耐喹诺酮类药物的影响

Effect on ramA of AcrAB efflux pump in quinolones-resistant Klebsiella pneumoniae

目的探讨AcrAB外排泵调控基因ramA对肺炎克雷伯菌耐喹诺酮类药物的影响。方法用喹诺酮类药敏纸片扩散法、MIC及其逆转实验和有机溶剂耐受实验测定细菌耐药表型,用PCR扩增外排泵结构基因acrA、acrB、tolC及调控基因acrR,ramA,marA,用半定量PCR检测调控基因的转录水平。结果泵的结构基因和调控基因均存在43株KP菌中。仅喹诺酮类耐药株与敏感株ramA转录水平存在统计学差异(P<0.05)。和对照组相比,高表达ramA的AC-1株,其泵结构基因的转录水平增高,耐药表型也有明显改变,用泵抑制剂后,其喹诺酮类的MIC恢复对照水平。结论 ramA是KP菌耐喹诺酮类抗生素的一个重要因素。抑制ramA的表达,有助于治疗多重耐药肺炎克雷伯菌的感染。

To explore effects of regulating gene ramA in AcrAB efflux pump of quinolones resistant Klebsiella pneu moniae （KP）, phenotypes of drug resistant bacteria were tested with K-B method, antibiotics minimal inhibitory concentration （MIC） and reversion experiments, and organic solvent tolerance （OST）. The structural genes acrA, acrB, tolC and the regu lating genes marA, ramA, acrR of AcrAB efflux pump have been found to exist in all 43 KP strains by PCR. With semi quan- titative RT PCR, the differences of the transcriptional levels of regulating gene ramA have been found between quinolones re- sistant strains and quinolones-sensitive strains （P〈0.05）. The ramA over expression in AC-1 strains could increase the tran- scriptional levels of their structure genes of the pump, and change their drug-resistant phenotypes, and then these phenotypes was back to the level of control after pump inhibiter was performed. Therefore, ramA is a important factor in KP against quin- olones. The inhibition of ramA expression is benefit to the treatment for infection of multidrug-resistant KP.