脉冲场凝胶电泳分型技术在追溯O139霍乱传染来源中的应用

Application of pulsed-field gel electrophoresis typing in tracing and carrying out surveillance programs on O139 cholera outbreaks

目的分析四川省2004年7起因聚餐暴发霍乱疫情的分离菌株之间,及其与常规监测中从外环境、水产品中分离的霍乱弧菌之间的分子分型特征和遗传相关性,查找霍乱传染来源。方法利用聚合酶链反应检测霍乱毒力基因(ctxAB),用脉冲场凝胶电泳(PFGE)对菌株进行分子分型,所得结果以BioNumerics V4.0软件UPGMA方法进行聚类分析。结果所试72株O139群霍乱弧菌中所有4株从河水分离的菌株ctxAB阴性,其余均具有ctxAB,为产毒株。对其中的67株菌以NotⅠ酶切后PFGE可分为16个型别。从甲鱼分离的O139群霍乱弧菌与同期流行的O139群霍乱弧菌优势PFGE型别一致,并且也为产毒株。7起暴发中分离的菌株型别各不相同。结论2004年四川省O139霍乱暴发感染来源复杂,提示并非因为菌株在该地持续存在而引起,但甲鱼可能是2004年度霍乱聚餐暴发的主要传染来源之一。

Objective To study the characteristics of molecular typing and phylogenic relationship among the Vibrio cholerae serogroup O139 strains isolated from environment and sea food samples during cholera outbreaks, in Sichuan province in 2004 and to trace the source of infections so as to support the ascertainment of epidemic control strategy. Methods Cholera toxin gene was detected by polymerase chain reaction amplification. Pulsed-field gel electrophoresis （PFGE） was used for subtyping of isolates and clustering of patterns was analysed with the software BioNumerics. Results In all the 72 strains under analysis, 68 appeared to be toxigenic while 4 from river water derived isolates were toxin gene negative. Sixty-seven strains were clustered into 16 PFGE patterns when digested with Not I ~ The patterns of toxigeinc O139 strains isolated from turtles in the markets were identical with the patterns of strains appeared in the outbreaks respectively. The PFGE patterns of isolates from different outbreaks were inconsistent. Conclusion The sources of infection causing these outbreaks were complicated. Contaminated turtles might also be one of the major sources of outbreaks when being served at the dinner parties in Sichuan in 2004.