广东地区副溶血性弧菌暴发分离优势血清型菌株的分子特征

Molecular characteristic of dominant serotypes of Vibrio parahaemolyticus isolated from foodborne disease outbreaks in Guangdong province

目的 研究广东地区多宗副溶血性弧菌暴发分离的优势血清型（O3：K6、O1：Kut、O4：K8）株的毒素基因携带情况、“大流行群”株分布特征以及不同血清型株之间的相关性.方法 对2008-2010年23起副溶血性弧菌暴发患者临床样本和当餐食品分离的62株优势血清型进行tdh、trh基因检测及“大流行群”鉴定（GS-PCR和orf8）,并利用Not Ⅰ酶切的脉冲场凝胶电泳（PFGE）分型方法分析了其中44株的谱型相似性.结果 96.8% （60/62）的分离菌株毒素基因检测结果为tdh＋,trh-；3株食品分离株携带tdh基因.分别有97.2%（ 35/36） O3：K6型、5.88% （1/17） O4：K8型、66.7% （8/9）的O1：Kut型菌株鉴定为“大流行群”（GS-PCR＋和/或orf8＋）.PFGE分型结果显示,44株分为3个聚类,属于“大流行群”聚类的28株之间的相似性为80.5%,与另外两个非“大流行群”聚类的相似性仅为59.5%；并发现部分“大流行群”O3：K6型分离株与O1：Kut、O4：K8呈现一致的PFGE谱型.结论 2008-2010年广东地区副溶血性弧菌暴发分离的优势血清型株大多携带tdh毒力基因；“大流行群”株以O3：K6和O1：Kut型占优；在同一宗暴发中,归属“大流行群”的不同血清型菌株存在高度相似性.

Objective To study the toxin genes and pandemic group distribution as well as the genetic correlation between the major serotypes（ O3：K6,O1：Kut,O4：K8 ） of Vibrio parahaemolyticus （VP） isolated from the outbreaks of Guangdong province.Methods The tdh and trh genes,GS-PCR and orf8 gene were detected on the 62 isolates sourced from patient and seafood occurred in the 23 outbreaks during 2008-2010.44 isolates of which were analyzed on PFGE digested by Not Ⅰ enzyme.Results Toxin genes distributions suggested that 96.8% （60/62）isolates were tdh＋,trh-.Three tdh＋ isolates sourced from seafood were found.Pandemic group distribution suggested that 97.2% （35/36） O3：K6,5.88% （1/17） O4：K8,66.7% （8/9）O1：Kut serotype was GS-PCR＋ and/or orf8＋,respectively.PFGE analysis suggested that 44 isolates were separated into 3 clusters,of which the similarity of PFGE profile was 80.5% in the pandemic group cluster constructed by 28 isolates,the similarity between pandemic group and non-pandemic group was 59.5%.Pandemic group of O3：K6,O1：Kut as well as 04：K8 isolated on some outbreaks were processing the same PFGE profiles.Conclusion The characteristic of toxin genes of major serotypes VP isolated in the outbreaks of Guangdong province form 2008-2010 was tdh- present and trh- absent.Within the pandemic group,O3：K6 and O1：Kut were the major serotypes.In single outbreak,isolates belongs to pandemic group but with different serotype seem to be close correlations.