大肠埃希菌O157:H7分离株MLVA分子分型

Characterization of Escherichia coli O157:H7 isolated in China by multiple-locus variable number of tandem repeat analysis

目的了解国内大肠埃希菌O157:H7菌株的分子流行特征。方法采用多位点可变数目串联重复序列分析(MLVA)方法对1999-2002年江苏、河南、安徽、山东、云南等地的大肠埃希菌O157:H7分离株135株进行分子分型,选取7个可变数目串联重复序列(VNTR)位点,应用PCR技术及毛细管电泳方法,检测分离株DNA多态性,使用BioNumerics软件进行聚类分析。结果 135株大肠埃希菌O157:H7可分为3个群(A群、B群、C群)38个MLVA型别,其中A群占20.7%(28/135)、B群占23.7%(32/135)、C群占55.6%(75/135);MLVA型别存在一定地域性,同一暴发来源的菌株具有相同MLVA型别。结论大肠埃希菌O157:H7国内分离株存在丰富的基因多态性;MLVA方法具有较高分子分型能力,可以在溯源和流行病学调查中发挥重要作用。

Objective To type the enterohemorrhagic Escherichi coli（E.coli） O157：H7 strains isolated in China by multiple-locus variable number of tandem repeat analysis（MLVA）.Methods Seven variable number of tandem repeat（VNTR） loci were chosen.E.coli isolates were typed by PCR and capillary electrophoresis.A dendrogram was constructed by BioNumeries.Results The 135 strains of E.coli O157：H7 isolated in China from 1999 to 2002 were classified into three clusters（A,B,C） and 38 MLVA types.The percentages of cluster A,B,and C were 20.7%（28/135）,23.7%（32/135）,and 55.6%（75/135）,respectively.The strains isolated in the same area shared a common MLVA type and the strains from an outbreak exhibited the same MLVA type.Conclusion The strains of E.coli O157：H7 isolated in China are genetic polymorphic.MLVA has a higher discriminative typing power and could contribute to better understanding of E.coli O157：H7 infection in epidemiologic investigation.