产超广谱β内酰胺酶大肠杆菌的检测及其耐药表型和基因型

Detection, resistant phenotype and genotype of extended spectrum β lactamase producing Escherichia coli

目的 研究临床分离的产超广谱 β内酰胺酶 (extendedspectrumβlactamases,ESBLs)大肠杆菌对常用抗生素的耐药性及其基因类型。方法 应用双纸片扩散法及Etest检测ESBLs ;微量稀释法测定产ESBLs大肠杆菌对临床常用抗生素的耐药性 ;全自动核型分析和脉冲场凝胶电泳 (pulsedfieldgelelectrophoresis,PFGE)研究产ESBLs大肠杆菌的基因型。结果 2 3株产ESBLs大肠杆菌共有 12种耐药表型 ,4种核型及 9种脉冲场凝胶电泳分型。耐药表型中 ,以对庆大霉素、妥布霉素、环丙沙星、四环素及TMP SMZ同时耐药组合最常见 ,占 39 1% ;基因分型中 ,核型 PFGE型 :2 42 5 2与 2 42 5 4各 4株分别分离自肝胆外科和血液科 ,3株 880 1 1a分离自高级病房 ,其余基因型呈散在分布于多个病房。结论 产ESBLs大肠杆菌对常用抗生素具有多种耐药表型 ;核型分析及脉冲场凝胶电泳是进行产ESBLs细菌引起医院感染流行病学研究的有效手段。

Objective To study the resistance and genotypes of extended spectrum β lactamase producing Escherichia coli isolated from clinical specimens. Methods Extended spectrum β lactamases (ESBLs) were detected by double disk synergy test and E test, the resistance of ESBL producing Escherichia coli to antibiotics was examined by microdilution and the genotypes of these isolates were studied by ribotyping and pulsed field gel electrophoresis(PFGE). Results There were in all 12 kinds of resistant phenotypes, 4 ribotypes and 9 PFGE types in 23 strains of ESBL producing Escherichia coli. The most common co resistance that accounted 39.1% strains was those against gentamicin, tobramycin, ciprofloxacin, tetracycline and trimethoprim/sulfamethoxazole. Although most genotypes were isolated from in different wards, 4, 4 and 3 strains of 242 5/2, 242 5/4 and 880 1/1a (ribotype/PFGE type) were isolated from the wards of hepatic surgery, hematology and first class ward. Conclusions ESBL producing Escherichia coli possessed multiple resistant phenotypes. Ribotyping and PFGE are useful technology for monitoring epidemiology of nosocomial infection caused by ESBL producing Escherichia coli.