大肠埃希菌临床分离株CTX-M型超广谱β-内酰胺酶基因型研究

Genotype analysis for extended-spectrum β-lactamase-producing Escherichia coli CTX-M

目的了解我院临床分离大肠埃希菌产CTX-M型超广谱β-内酰胺酶(ESBLs)的基因型分布情况。方法收集我院临床分离大肠埃希菌200株,按美国临床和实验室标准协会2006年制订的标准确定ESBLs表型。PCR扩增CTX-M耐药基因,扩增产物测序,测序结果与GenBank比对,确定CTX-M基因型。结果200株大肠埃希菌中有94株ESBLs阳性,其中92株CTX-M基因扩增阳性。测序结果表明,大肠埃希菌CTX-M基因型以CTX-M14为主,占67.4%,同时CTX-M3占27.2%,5株未分型。结论大肠埃希菌中产CTX-M型ESBLs的检出率较高,其基因型以CTX-M14和CTX-M3型为主。

Objective To investigate the genotype of CTX-M extended-spectrum β-lactamases （ESBLs） -producing Escherichia coli （ E. coli） in clinical isolates. Method The clinically isolated E. coli strains including 200 strains from our hospital were collected. Based on the standard of CLSI2006, the ESBLs-producing E. coli were identified. CTX-M gene was amplified by PCR. The amplified DNA sequences were analyzed by DNA sequencer, and the CTX-M genotype was con- firmed by comparing the sequenced CTX-M gene with the GenBank database. Result The positive rate of ESBLs-produ- cing E. coli was 47.0% （94/200）. CTX-M gene was amplified in 92 strains by PCR. The results of DNA sequencing showed that the main genotypes of 92 CTX-M positive E. coli isolates were CTX-MI4 and CTX-M3. Among them, CTX- M14 accounted for 67.4%, and CTX-M3 accounted for 27.2%. Five strains were unidentified. Conclusion The preva- lence of CTX-M ESBLs E. coli is high, and the dominating genotypes are CTX-M14 and CTX-M3.