O139群霍乱弧菌分子流行病学研究

目的分析2001-2006年广州地区霍乱暴发、散发事件及外环境监测中分离的O139群霍乱弧菌的致病相关基因型和PFGE型,追踪菌株的来源和变迁,探讨本地区O139群霍乱流行特点。方法采用多重PCR方法检测O139群菌株的4种致病相关基因,应用脉冲场凝胶电泳技术(PFGE)对菌株进行分子分型,采用软件Bio Numerics Version4.0对分型数据进行处理和分析。结果广州地区O139群菌株中存在2种致病相关基因型,即A型和C型,18株感染者相关菌株中,除1株外,均为致病相关基因A型;10株珠江水分离株均为致病相关基因C型。28株O139群霍乱弧菌分为20个不同的PFGE型,归为4个聚类群(Ⅰ、Ⅱ、Ⅲ、Ⅳ群)。珠江水中O139群菌株存在PFGE克隆型的多样性。O139群暴发中分离的菌株PFGE型相同或相近,O139群散发疫情中的病例分离株与部分暴发株也具有相同或相近的PFGE型。结论分子分型方法结合流行病学资料,可分析O139群霍乱菌株的流行特点,致病相关基因分型可代替噬菌体-生物分型来判断和区分O139群霍乱弧菌的流行株与非流行株,从而为霍乱的预防、控制和预警提供科学依据。

Molecular epidemiological survey on Vibrio cholerae serogroup O139

The pathogenicity-related genotype and the types in pulse-field gel electrophoresis technique (PFGE) of V.cholerae serogroup O139 isolated from cholera outbreak , endemic cases and environmental surveillance from 2001 to 2006 in Guangzhou area were analyzed in order to track the sources and changes of V.cholerae O139 infection, and to investigate the characteristic of V.cholerae serogroup O139 in local area, multiplex polymerase chain reaction (mPCR) assay was employed to detect the 4 different kinds of pathogenicity-related genes. PFGE was used for the molecular subtyping of V.cholerae O139, and its PFGE patterns were analyzed by BioNumerics version 4.0 software. It was demonstrated that there were two types of pathogenicity-related genes of V.cholerae O139 isolated in Guangzhou area, namely, type A and C. in which 17 clinical isolates from human source belonged to type A and 10 strains isolated from Pearl River belonged to type C. There were 20 distinct types determine by PFGE subtyping among 28 isolates, which could be separated into 4 groups through cluster analysis ( Group I, II, III, IV). Diversity in PFGE subtyping could be detected in the strains of V.cholerae O139 isolated from Pearl River. In addition, the subtypings with PFGE of clinical isolates during outbreak of infection with V.cholerae O139 were almost identical or closely related, however, among the isolates from the endemic cases, identical or closely related PFGE subtypings to some of the outbreak cases could be detected. The identical and closely related PFGE subtyping might show differences in 1-4 bands existing in the isolates of cholerae O139 outbreak. From the above observations, it is evident that the molecular subtyping methods together with epidemiologic investigation data can be used to analyse the epidemic characteristics of cholera infection caused by V.cholerae serogroup O139 and contribute to be employed as an alternative to the phage-biological typing.