副溶血性弧菌引起食源性疾病暴发事件调查与病原特征分析

Investigation and pathogenic characteristics of food-borne disease outbreak caused by Vibrio parahaemolyticus

目的调查和分析山西省阳泉市一起食源性疾病暴发事件中副溶血性弧菌的病原特征,提高对食物中毒应急事件的处理能力。方法使用脉冲场凝胶电泳(PFGE)、血清学分型、毒力基因检测、药物敏感实验和全基因组测序的方法分析25例有腹泻、腹痛、恶心、呕吐等消化道症状的患者分离出的11株分离菌株。结果11株分离菌株均为副溶血性弧菌,其中8株副溶血性弧菌分离株携带毒力基因tdh,1株同时携带毒力基因trh和tdh,1株只携带毒力基因trh,1株只有毒力基因tlh。血清型分为3种型别,分别是O10:K4、O4:K63以及O5:unknown。根据11株副溶血性弧菌的PFGE图谱将菌株分为5种不同的群,基于全基因组序列的分析显示8株来自患者的副溶血性弧菌具有相同的ST型,属于同一克隆群。副溶血性弧菌病原体毒力、耐药基因和药敏表型相同,符合暴发流行病学特征,判断其为该起食物中毒事件的病原体。11株菌均只含有blaCARB耐药基因,且未检测到耐药质粒,对氯霉素、萘啶酸、四环素、美罗培南、阿米卡星、氨苄西林、厄他培南、替加环素、头孢噻肟、头孢他啶和环丙沙星均敏感,对多黏菌素E中度敏感,均无耐药表型。结论这是一起由多种血清型副溶血性弧菌污染了食品而导致的食源性疾病暴发事件。该食堂储存食物时生熟不分,副溶血性弧菌机会性繁殖在合适的含盐食物中也可以增殖,进而引起该起事件发生。

Objective To investigate and analyze the pathogenic characteristics of Vibrio parahemolyticus in a food-borne disease outbreak in Yangquan City,Shanxi province,and improve the ability to deal with food poisoning emergencies.Methods Totally 11 isolated strains from 25 patients with gastrointestinal symptoms such as diarrhea,abdominal pain,nausea and vomiting were analyzed using pulsed field gel electrophoresis(PFGE),serotyping,virulence gene detection,drug sensitivity assay and whole genome sequencing.Results All the 11 isolates were Vibrio parahaemolyticus,of which,eight carried a virulence gene tdh,one carried both virulence genes trh and tdh,one carried only a virulence gene trh,and one carried only a virulence gene tlh.The isolates were classified into three serotypes,O10:K4,O4:K63 and O5:unknown.According to the PFGE profile,11 strains were divided into five different groups.The results of the whole genome sequence showed that eight strains were the same ST type and were classified to the same clonal group.The virulence gene distribution,the drug resistance gene existence and the drug susceptibility profiles were the same,which was consistent with the epidemiological characteristics of the outbreak.All 11 strains only contained blaCARB resistance gene,and no drug-resistant plasmid was detected.They were sensitive to chloramphenicol,nalidixic acid,tetracycline,meropenem,ampicillin,ertapenem,tigacycline,ceftazidime and ciprofloxacin,and moderately sensitive to polymyxine E.None of the isolates were resistant to antibiotic drugs.Conclusion This is a food-borne disease outbreak caused by contamination of food with multiple serotypes of Vibrio parahaemolyticus.The cooked and uncooked food is stored together in the canteen to induce the opportunistic reproduction of Vibrio parahaemolyticus in suitable salty food,which leads to the occurrence of the incident.