肠杆菌科临床株产超广谱β-内酰胺酶的基因多样性研究

Gene diversities of ESBLs in clinical isolates of Enterobacteriaceae

目的 研究本地肠杆菌科临床株产超广谱 β 内酰胺酶 (ESBLs)的基因型。方法 采用K B法、接合传递试验、质粒谱分析、PCR、PCR 限制性片段长度多态性分析 (RFLP)及DNA序列分析等方法对 3 3株产ESBLs肠杆菌科临床株的表型及基因型进行分析。结果 3 3株临床株对头孢噻肟的耐药率为 85 % ,明显高于头孢他啶。PCR检测结果为 2 8株临床株携带blaCTX M ESBLs ,2 4株携带blaTEMDNA ,9株携带blaSHVDNA。PCR RFLP检测结果为临床株EC98A7的TEM酶含有E10 4K突变 ,未发现发生G2 3 8S突变的SHV酶。DNA序列分析及同源性比较表明 4株临床株(EC98A7、EB5 6、CFR78及KP9941)的blaCTX MDNA片段属于CTX M亚组 1,分别与blaCTX M 3和blaCTX M 12的同一性最高。结论 本地肠杆菌科临床株 85 %携带CTX M型 ,多数菌株同时携带 2种以上 β 内酰胺酶。大肠杆菌EC98A7同时携带CTX

Objective To study the Genotype of local clinical isolates of Enterobacteriaceae producing extended spectrum β lactamases. Methods K B test, conjugative transfer test, plasmid profile analysis, PCR, PCR RFLP, and DNA sequencing were used to detect the phenotype and genotype of 33 isolates of Enterobacteriaceae producing ESBLs. Results Eighty five percent of 33 isolates was resistant to cefotaxime which was obviously higher than that to ceftazidime. blaCTX M ESBLs was detected in 28 isolates by PCR, blaTEM DNA in 24 isolates, and blaSHV DNA in 9 isolates. Mutation of E104K was only identified in one TEM β lactamase produced by EC98A7 by PCR RFLP. No substitution of G238S occurred in 9 SHV β lactamases. DNA sequencing and DNA alignment showed the blaCTX M DNA fragments from 4 clinical isolates of EC98A7,EB56,CFR78 and, KP9941 belonged to CTX M type 1, with highest identity to blaCTX M 3 or blaCTX M 12 respectively. Conclusions CTX M ESBLs is carried in 85% isolates of Enterobacteriaceae producing ESBLs in this city. Most of the isolates carry 2 or more β lactamases. E. coli EC98A7 produces two ESBLs, a TEM ESBL and a CTX M ESBL.