北京市丰台区腹泻患者肠毒素性大肠埃希菌的分布与分子分型特征

Distribution and genotyping analysis of enterotoxigenic E. coli in diarrheal patients in Fengtai District of Beijing

目的了解北京市丰台区腹泻患者肠毒素性大肠埃希菌(ETEC)的分布与分子分型特征,分析2种分型方法的应用价值,为ETEC的分子流行病学研究提供参考依据。方法对腹泻患者便标本分离培养,采用脉冲场凝胶电泳技术(PFGE)和多位点序列分型(MLST)2种方法进行分型比较。结果55株ETEC分离株PFGE分型得到40种型别,呈多态性;MLST分型得到19个型别,ST-6010与ST-69是最主要的ST型别,部分试验菌株形成2个ST克隆群,分别为STC-6007、STC-3103。多数菌株的遗传关系较远,可能与菌株来源多样有关。结论ETEC感染在腹泻患者中长期存在,遗传关系呈多元化。2种分子分型方法的结合,从基因水平上解释了ETEC的流行特征及变化趋势。

Objective To study the distribution and molecular characteristics of enterotoxigenic E.coli(ETEC)with diarrheal patients in Fengtai District of Beijing,and to assess the application value of pulsed-field gel electrophoresis(PFGE)and multilocus sequence typing(MLST),providing a scientific basis for further molecular epidemiology study of ETEC.Methods Pathogenic bacteria were isolated from patients with acute diarrhea.Molecular characteristics were detected by using PFGE and MLST.Results All 50 strains of ETEC were divided into 40 PFGE types with highly polymorphic;while they were divided into 19 ST types based on MLST typing,with ST-6010 and ST-69 the most prevalent types.Some of the tested strains were divided into 2 groups,STC-6007 and STC-3103,each of them belonging to an evolutionary branch.Most other strains showed little genetic correlation.Diversity of strains was most related with the diversity of strain sources.Conclusion ETEC is an important pathogen associated with diarrhea,showing a diverse genetic relationship.The combination of two molecular typing methods explained the epidemic characteristics and variation trend of ETEC at the gene level.