一起副溶血弧菌食源性疾病暴发事件病原学检测结果分析

Etiology analysis of a foodborne disease outbreak caused by Vibrio parahaemolyticus

目的应用实时荧光PCR技术和脉冲场凝胶电泳分子分型技术对一起副溶血弧菌(Vibrio parahaemolyticus,Vp)导致的食源性疾病暴发事件进行病原学分析,为类似事件处理提供经验。方法收集暴发事件流行病学资料,采集病例、可疑污染食品、环境样本;使用实时荧光PCR检测技术进行病原筛查及毒力基因检测;使用常规培养技术进行样本病原菌分离;使用PFGE进行菌株分子分型;应用国家致病菌识别网对食品分离株和病例分离株进行聚类分析;将食品分离Vp菌株中携带tdh基因情况和食品增菌液中toxR和tdh基因扩增ct值进行分析比较。结果 3件病例粪便样本和2件可疑污染食品分离到Vp菌株(toxR+/tdh+/trh-,O3:K6血清型),且PFGE图谱成簇(相似度93.94%);1件可疑污染食品分离到Vp菌株(toxR+/tdh-/trh-),与另外5株Vp的PFGE图谱不成簇。2件分离到Vp(tdh+)菌株的食品样本,其增菌液2种基因(toxR和tdh)实时荧光PCR检测ct值接近;分离到Vp(tdh-)菌株的食品样本,其增菌液toxR基因扩增ct值小于tdh基因较多。结论本次事件为一起Vp导致的食源性疾病暴发,食品增菌液实时荧光PCR检测对Vp导致的食源性疾病快速诊断和病原学分析具有重要价值。

Objective To analyze the etiology of a foodborne disease outbreak caused by Vibrio parahaemolyticus(Vp) by real-time PCR and pulsed-field gel electrophoresis molecular typing, and provide experience for management of similar events. Methods Epidemiological data of the outbreak were collected. Samples of the diarrhea patient, suspected contaminated foods and environment were collected, and real-time PCR was used for pathogen screening and virulence gene detection, and bacterial were isolated by conventional culture method;Pulsed field gel electrophoresis(PFGE) method was used for molecular subtyping of the strains;Cluster analysis of the isolates was carried out using China Pathogen Identification Net(PIN). The detection result of tdh by real-time PCR in isolates of Vp from suspected foods and the ct value of toxR and tdh in the enrichment medium of suspected contaminated food were compared. Results Five Vp strains(toxR+/tdh+/trh-, O3:K6) were isolated from all three diarrhea patients’ stool and two suspected contaminated foods, and the PFGE patterns were divided into 2 closely related clusters(93.94% similarity). One Vp strain(toxR+/tdh-/trh) was isolated from another suspected contaminated food, and the PFGE pattern has low similarity with the other 5 Vp strains. The suspected contaminated foods which isolated the Vp strains(tdh+) showed similar ct values of toxR and tdh in each enrichment medium, while the food which isolated the Vp strains(tdh-) showed much lower ct value of toxR than tdh in the enrichment medium. Conclusion This event is a foodborne disease outbreak caused by Vp. real-time PCR detection of the enrichment medium of suspected contaminated foods is of great value for rapid diagnosis of foodborne disease outbreak caused by Vp and etiology analysis.