耐碳青霉烯类大肠埃希菌耐药基因型检测与同源性分析

Genotypes of drug resistance genes in carbapenem-resistant Escherichia coli and analysis of homology

目的探讨医院感染耐碳青霉烯类大肠埃希菌的耐药传播机制及克隆流行,为临床治疗提供参考依据。方法收集2011年1月-2012年6月医院临床分离的19株耐碳青霉烯类大肠埃希菌,采用PCR及序列比对等方法检测耐药基因的分布;脉冲场凝胶电泳和多位点序列分型进行菌株同源性分析,数据采用SPSS 17.0进行统计分析。结果共19株耐碳青霉烯类大肠埃希菌,检出科室以EICU检出最多,共8株占42.11%;共检出产KPC-2型碳青霉烯酶菌株17株;11株细菌同时编码ESBLs基因,包括携带blaKPC-2、blaCTX-M-14和blaTEM-13种β-内酰胺酶基因;脉冲场凝胶电泳证实有9个克隆株,其中A克隆共8株细菌,是主要流行的克隆;多位点序列分型结果显示3株产KPC-2菌株均为ST131型。结论产KPC酶大肠埃希菌同时携带有其他耐药基因,CTX-M型超广谱β-内酰胺酶最为常见;ST131型产KPC-2大肠埃希菌在中国出现,同时也扩大了其在世界流行范围。

OBJECTIVE To explore the transmission mechanisms of drug resistance and clone spread of the carbap‐enem‐resistant Escherichia coli causing nosocomial infections so as to provide guidance for clinical treatment . METHODS From Jan 2011 to Jun 2012 ,totally 19 clinical isolates of carbapenem‐resistant E .coli were collected , then the drug resistance genes were detected by using PCR and sequence alignment method ,the homology of the strains was analyzed with the use of pulse‐field gel electrophoresis （PFGE ） and multilocus sequence typing （MLST ） ,and the statistical analysis of data was performed with the use of SPSS 17 .0 software .RESULTS A to‐tal of 19 strains of carbapenem‐resistant E .coli were isolated ,of which 42 .11% （8 strains） were isolated from the EICU .Totally 17 strains of type KPC‐2 carbapenemase‐producing strains were detected ,and 11 strains simultane‐ously harbored the ESBLs encoding genes ,including three genotypes of β‐lactamase genes （blaK PC‐2 ,blaCTX‐M‐14 ,and blaTEM‐1） .The PFGE indicated that there were 9 clone strains ,and 8 strains were the clone A , which was the most prevalent clone ;the results of the MLST showed that all the three KPC‐2‐producing strains belonged to ST 131 .CONCLUSION The KPC‐producing E .coli strains simultaneously harbor other drug resist‐ance genes ,and the type CTX‐M ESBLs is the most common .The type ST131 KPC‐2‐producing E .coli strains have emerged in China and may expanded the range of prevalence in the world .