万古霉素耐药肠球菌的同源性及耐药机制分析

Molecular Characterization of Vancomycin-resistant Enterococci

目的探讨万古霉素耐药肠球菌(VRE)的同源性及主要耐药机制。方法收集我院临床分离的9株VRE,采用E-test法检测其对万古霉素等10种抗菌药物的最低抑菌浓度值,脉冲场凝胶电泳技术进行同源性分析,多重PCR技术扩增万古霉素耐药基因并测序。结果9株VRE均为屎肠球菌,共分为6个克隆,耐药表型和基因型均为vanA型。结论本院VRE为vanA基因型,VRE的增加与局部克隆传播、耐药基因的水平转移以及抗菌药物的选择压力有关。

Objective To investigate the homology and resistant mechanism of vancomyein-resistant Enterococci （VRE） isolates. Methods A total of 9 VRE isolates were collected from 2006 to 2007 at PUMC hospital. The susceptibility of these isolates to 10 different antibiotics including vancomycin was tested by E-test. These strains were processed by brain heart infusion agar screening in the presence of vancomycin （6μg/ml） , and were analyzed for genotypic characteristics using the multiplex PCR. The homology of the isolates was determined by pulsed-field gel electrophoresis （PFGE）. Results All the 9 VRE isolates were identified as Enterococci faecium. The visual analysis of PFGE patterns revealed 6 different PFGE types. The vanA gene was confirmed by PCR and sequencing in 9 VRE isolates, which were consistent between phenotype and genotype for glycopeptides resistance. Conclusions Only vanA genotype was detected in PUMC hospital. Clonal dissemination, horizontal gene transfer, and the selective pressure of antimicrobial agents may contribute to the increase of VRE.