2012年湖北省霍乱的病原学研究及溯源分析

A study on the pathogenic characteristics and traceability of Vibrio cholera strains circulated in Hubei province in 2012

目的分析2012年湖北省霍乱流行的病原学特征，应用脉冲场凝胶电泳分析各疫情菌株之间的遗传相关性，查找霍乱传染来源，为制定防治措施提供依据。方法对35株霍乱弧菌菌株进行常规生化鉴定和毒素基因检验，以及药敏试验，采用脉冲场凝胶电泳（PFGE）技术获得电泳酶切指纹图谱并对图谱进行聚类分析。结果35株霍乱弧菌经检验均为霍乱0139群，产毒株占71．42％，霍乱弧菌耐药结果显示四环素、复方新诺明、利福平耐药率分别为57．14％、88．57％、80．00％。PFGE电泳图谱条带总相似率为80％～100％，具有一定的同源性。三起疫情中相同地区的大部分菌株都聚为一类，同源性为100％，提示为相同菌株感染所致；仅来源于荆州地区甲鱼中分离的菌株单独为一类与其他菌株不同。结论2012年湖北省霍乱弧菌的优势菌株为0139群，大部分产毒。药敏结果显示，菌株对四环素、复方新诺明、利福平大部分耐药；对亚胺培南、头孢曲松高度敏感；疫情中相同地区的大部分菌株聚为一类属于同一来源，不同地区的菌株有一定的变异，几起疫情暴发均与聚餐有关，所以注意食物卫生，从甲鱼中分离的菌株不产毒，提示甲鱼可能并不是疫情的主要毒株来源，应密切关注海、水产品的监测情况。

Objective Toinvestigate the pathogenic characteristics of Vibrio cholera strains isola- ted from Hubei province in 2012, and to identify the source of infection by analyzing their genetic correla- tions. Methods The biochemical identification, toxin gene detection and drug susceptibility test were car- ried out to analyze a total of 35 Vibrio cholera strains isolated from three epidemic areas. Comparison of ge- nomic DNA fingerprints and cluster analysis among isolates of Vibrio cholera was conducted by using pulsed- field gel electrophoresis （PFGE）. Results All of the 35 strains were Vibrio cholera O139, of which 71.42% were toxic strains. The drug resistance rates of Vibrio cholera strains to tetracycline, cotrimoxazole and rifampincin were 57.14%, 88.57% and 80.00%, respectively. Analysis of genomic DNA fingerprints of the isolates showed highly similar with similarity values ranging from 80% -100%. Most of the strains iso- lated from the same epidemic area fell into the same one cluster with 100% homology in genome Only a strain isolated from turtle in Jingzhou area was belong to a different cluster. Conclusion The Vibrio cholera 0139 strains were the dominant strains causing the outbreaks of cholera in Hubei province in 2012. Most of them were toxigenic strains. A large majority of the strains had developed resistance to tetracycline, eotri- moxazole and rifampincin, but all strains showed high susceptibility to ceftriaxone and imipenem. Vibrio cholera strains isolated from the same epidemic area were mainly belonged to the same one cluster, sugges- ting the same source of infection. However, the strains varied among different epidemic area. Follow-up in- vestigations of three outbreaks of cholera in this study were all associated with food infection. Therefore, more attention should be paid to food sanitation and safety measurement. Although a non-toxigenic strain iso- lated from turtle was not associated with the epidemic of cholera, surveillance for seafood and aquatic prod- ucts would still be necessary.