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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 understand the molecular epidemiology of Escherichia coli O157: H7 in China. Methods A total of 135 Escherichia coli O157: H7 isolates from 1999 to 2002 in Jiangsu, Henan, Anhui, Shandong and Yunnan were genotyped by MLVA (Multiple Site Variable Number Tandem Repeat Analysis) Seven variable number of tandem repeat (VNTR) loci were detected by polymerase chain reaction (PCR) and capillary electrophoresis. DNA polymorphism of the isolates was detected by BioNumerics software. Results 135 strains of Escherichia coli O157: H7 were divided into 38 MLVA types in 3 groups (group A, group B and group C), of which group A accounted for 20.7% (28/135) and group B 23.7% 32/135), and 55.6% (75/135) in group C. The genotypes of MLVA were of a certain locality, and the strains of the same outbreak were of the same MLVA type. CONCLUSION: The domestic isolates of Escherichia coli O157: H7 are rich in genetic polymorphisms. The MLVA method has a higher molecular typing ability and can play an important role in traceability and epidemiological investigation.