一起O139霍乱暴发的传染来源分析

Analysis of the source of a cholera outbreak caused by O139 Vibrio cholera

目的对一起霍乱暴发疫情中来自患者和甲鱼的O139群霍乱菌株分离株分子特征分析,判断传染来源。方法对疫情调查中的3株患者分离株和3株来自水产市场甲鱼标本的分离株,采用聚合酶链反应(PCR)检测分离菌株的毒力相关基因(ctxAB、toxR、zot);用脉冲场凝胶电泳技术(PFGE)对菌株进行分子分型,所得结果以Bio-Numeric V4.0软件进行聚类分析。结果6株菌所有毒力相关基因全部阳性,均为产毒株。6株菌可得2个PFGE型,其中2株甲鱼株与3株患者株带型相同,1株甲鱼株独立成型。通过Pulse Net China数据库搜索,6株菌与中国某省O139群霍乱弧菌聚餐暴发菌株分子分型不同。结论此次霍乱暴发疫情中甲鱼为可能的传染来源,提示该地区在今后霍乱防治工作中,应注意以甲鱼为重点的水产品的安全。

Objective The study was conducted to trace the source of cholera infection by analyzing the molecular characteristics of the Vibrio cholera O139 isolates obtained from patients and snapping turtles involved in a cholera outbreak. Methods Three strains of Vibrio isolated from patients and three from snapping turtles on aquatic products markets associated with the epidemic were analyzed for the virulence-related genes （ctxAB, toxR, zot） using PCR and subtyped using PFGE. Cluster analysis was conducted using Bio-Numeric V 4.0. Results All six V.cholera strains were positive for the virulence-related genes, which indicated that they were all toxigenic. Clustering into two PFGE subtypes, these strains contained one subtype that was identically found in two isolates from snapping turtles and other three from patients, and another from turtles that formed a separate subtype. Both subtypes of the six isolates were different from those of the V.cholera O139 detected in a food-borne outbreak in other province of China, according to the information from the Pules Net China database. Conclusion The snapping turtle was a potential source of the cholera outbreak, Turtles from markets might have been contaminated with V.cholera O139 that carried virulence genes. Therefore, such aquatic products as especially snapping turtles should be focally inspected so as to better control and prevent cholera in this area.