湖南省2012年霍乱弧菌病原学特征分析

Analysis on the etiological characteristics of Vibrio cholera in Hunan Province in 2012

目的了解2012年湖南省不同地区不同时间各疫情菌株的病原学特征,分析比较各疫情分离株之间以及与常规监测分离株之间的遗传相关性,为追溯传染源提供依据。方法利用生化鉴定系统进行菌株鉴定,血清学方法生物分型,PCR方法检测毒力基因和脉冲场凝胶电泳技术(PFGE)进行分子分型。结果 2012年从湖南省疫情和监测样品中分离的17株O139群霍乱弧菌均带毒力基因,均为产毒株。在进行PFGE分子分型的17株菌中,有2起疫情酶切图谱完全相同,而该2起疫情与其他的3起疫情以及这3起疫情之间的酶切图谱不完全相同。结论湖南省2012年从甲鱼中分离的O139群霍乱弧菌毒力基因携带率高,是疫情频发的一个重要原因。从病人和食品中分离的菌株具有高度同源,进一步证实该疫情为食源性传播。分子分型图谱相似率100%的2起疫情传染来源一致,而其他各起疫情之间关联性很小或者没有,传染来源均不同。

Objective To investigate the etiological features of the epidemic strains at different time points from different areas in Hunan Province in 2012, to analyze the genetic correlation between the epidemic strains and routine monitoring strains, and to provide a basis for tracing the source of infection. Methods Bacterial strains were identified by biochemical identification system, serotyped by serological methods, and then characterized by polyrnerase chain reaction （PCR） for detecting virulence associated genes. Pulsed field gel electrophoresis （PFGE） was used to analyze molecular typing of Vibrio cholera strains. Results All 17 strains of Vibrio cholerae serotype O139 isolated from the epidemic and routine monitoring in Hunan Province in 2012 were toxin production strains with virulence genes. Among the 17 strains for molecular typing by PFGE, the enzyme cut maps of 2 strains from 2 different epidemic situations were exactly the same, but different from those of 3 other epidemic situations which were not exactly the same. Conclusions The high carrying rate of virulence genes of Vibrio cholerae O139 isolates from soft shelled turtles in Hunan Province in 2012 is one of the important reasons for frequent outbreaks. The high homology of isolates from patients and foods further confirms that the outbreaks are attributed to forborne cholera transmission. 2 outbreaks have 100 % identity of molecular typing maps, while other outbreaks have little association, which shows different sources of infection.