产AmpC酶的大肠埃希菌中PBP4的检测及分析

摘要

Objective To detect the mRNA expression level of the nonessential penicillin-binding protein 4 (PBP4)dacB gene in AmpC beta-lactaraase producing Escherichia coli isolates, and investigate the effect of PBP4 in the resistant mechanism of AmpC beta-lactamase producing gram-negative isolates. Methods- A total of 34 AmpC beta-lactamase producing Escherichia coli isolates were collected in Shanghai Sixth People's Hospital from 2003 to 2010. The polymerase chain reaction (PCR)was used for the amplification of dacB gene and ampC gene, and the real-time quantitation PCR was used for the detection of the mRNA expression level of dacB. The isolates were classified into 2 groups: the high expression level group and the low expression level group. Real-time quantitation PCR was used for the detection of the mRNA expression level of ampC. The broth microdilution method was used for the detection of sensitivity. Results Among the 34 Escherichia coli,26 (76.47%)of 34 isolates had mRNA overexpression level of dacB,and the mRNA of ampC in the high expression level group was higher than that in the low expression level group (P < 0.05). Conclusions The overexpression of PBP4 may be helpful to introduce high-level resistance by triggering the overexpression of AmpC beta-lactamase among clinical isolates of Escherichia coli.%目的 检测产AmpC β-内酰胺酶(简称AmpC酶)的大肠埃希菌中编码非必需青霉素结合蛋白4( PBP4)的基因dacB mRNA表达水平,探讨PBP4在产AmpC酶的革兰阴性菌耐药机制中的作用.方法 收集上海市第六人民医院2003至2010年间部分产AmpC酶的大肠埃希菌34株,聚合酶链反应(PCR)扩增dacB基因和ampC基因,实时定量PCR检测dacB mRNA表达水平,并分为dacB mRNA表达上调组与dacB mRNA表达下调组,实时定量PCR方法检测ampC mRNA表达水平.微量肉汤稀释法药敏试验检测抗菌药物的敏感性.结果 34株大肠埃希菌中,26株(76.47％) dacB mRNA表达水平上调,dacB mRNA表达水平上调组ampC mRNA表达水平高于下调组,P＜0.05.结论 推测大肠埃希菌临床菌株中PBP4高表达有助于产生AmpC酶的高表达,从而引起细菌耐药性的增加.