主动外排系统与阴沟肠杆菌多重耐药关系的研究

The Study of Relationship between Active Efflux System and Multidrug resistance of Enterobacter cloacae

目的观察泵抑制剂氰氯苯腙对阴沟肠杆菌耐药水平的降低作用,并扩增外排基因,以探讨主动外排系统的基因分布及与阴沟肠杆菌多重耐药的关系。方法采用琼脂稀释法测定氰氯苯腙应用前后83株阴沟肠杆菌对头孢他啶、阿米卡星、阿奇霉素、左氧氟沙星、四环素的最小抑菌浓度变化,PCR扩增外排系统基因acrA、acrB、toiC,PCR产物连接转化后采用sanger末端终止法进行测序。结果以上述5种抗生素为底物,分别有30、36、19、32、28株显示外排表型阳性。PCR扩增结果显示,分别有55、57、62株菌检测得到acrA、acrB、toiC,并通过测序证实。结论主动外排泵抑制剂可降低阴沟肠杆菌对抗生素的耐药水平,相对于非多重耐药株,外排泵对多重耐药株的影响较大。主动外排系统是阴沟肠杆菌多重耐药的重要机制之一。

Objective To observe the effect of efflux inhibitor CCCP on the resistence deereasedlevel of E. cloacae and analyze distribution of efflux system genes. To explore the relationship between active efflux system and multidrug resistance of E. cloaca. Methods To detect minimum inhibitory concentrtion change of E. cloacae to eeftazidime,amikaein,azithromycin,levofloxaein and tetracycline with and without CCCP by using agar dilution method, PCR amplified aerA,acrB, toiC, PCR products were confirmed by Sanger termination sequencing. Results Efflux phenotype showed to be positive in 30,36,19,32 and 28 strains to the five antibiotics,respectively, with 10μg/mL CCCP. PCR amplification showed 55,56,61 strains were detected to carry acrA, aorB, toiC, re2 spectively,and confirmed by DNA sequencing. Conclusion The efflux pump inhibitor CCCP can increased susceptibilty to antibiotics of E. cloacae,Compared with susceptible strains,the effect of active efflux system on resistant strains is more significant. Active efflux systerm is One of important mechnisms leading to multidrug to antibiotics of clinical islated E. cloacae.