烟台地区食源性疾病中副溶血性弧菌的病原特征及溯源分析

目的了解烟台地区引发食物中毒的副溶血性弧菌分离菌株的主要血清型、抗生素耐药情况、致病力的强弱以及传播流行趋势。方法对2017～2019年11起食物中毒爆发事件中分离的14株副溶血性弧菌进行血清分型;采用微量肉汤稀释法进行药敏试验;采用PCR技术检测毒力基因不耐热溶血素(tld)、耐药直接溶血素(tdh)和溶血相关溶血素(trh);采用脉冲场电泳(pulse-field gel electrophoresis,PFGE)进行分子分型的溯源分析。结果引发烟台地区食物中毒爆发的副溶血性弧菌血清型多样,但以O3:K6型为主(28.6%),分离菌株中11株(78.6%)表现为tdh阳性和trh阴性,3株(21.4%)未携带tdh和trh基因,对头孢唑啉(71.4%)、多粘菌素E(57.1%)、美罗培南和阿莫西林/克拉维酸(7.1%)均出现耐药情况,对氨苄西林(21.4%)、多粘菌素B(14.3%)为中度敏感,耐药谱显示没有出现对3种以上同时耐药的情况,但是42.9%的分离菌株对2种同时耐药情况。结论烟台地区引发食物中毒爆发的副溶血性弧菌以O3:K6型为主,主要携带tdh,对头孢唑啉耐药和多粘菌素耐药普遍存在,具有聚集性爆发的风险,因此加强腹泻病的监测,充分利用国家致病菌识别网集中进行本地区分离菌株的病原特征研究是防控食物中毒爆发的有效手段。

Pathogenic characteristics and traceability analysis of Vibrio parahaemolyticus in food-borne diseases in Yantai

Objective To understand the main serotypes, antibiotic resistance, pathogenic strength and epidemic trends of isolates of Vibrio parahaemolyticus that caused food poisoning in Yantai. Methods A total of 14 strains of V. Parahaemolyticus isolated from 11 food poisoning outbreaks from 2017 to 2019 were serotyped. The drug sensitivity test was carried out by microdilution broth method. The toxic gene of thermolabile hemolysin (tld), drug resistance direct hemolysin (tdh) and hemolysis-related hemolysin (trh) were detected by PCR technology. Traceability analysis of molecular typing was realized by pulse-field gel electrophoresis (PFGE). Results The serotypes of Vibrio parahaemolyticus that triggered the outbreak of food poisoning in Yantai area were diverse, but mainly was O3:K6 type (28.6%). Among the isolated strains, 11 isolates (78.6%) showed tdh positive and trh negative, 3 strains (21.4%) were not carrying the tdh and trh genes. Resistance to cefazolin (71.4%), polymyxin E (57.1%), meropenem and amoxicillin/clavulanic acid (7.1%) all occurred. Sensitivity to ampicillin (21.4%) and polymyxin B (14.3%) was moderate sensitivity. The drug resistance spectrum showed that there was no resistance to more than three kinds of simultaneous resistance, but 42.9% of the isolated strains were resistant to two kinds of simultaneous resistance. Conclusion Vibrio parahaemolyticus causing food poisoning outbreaks in Yantai area is mainly O3: K6, mainly carrying tdh, drug resistance to cefazolin and polymyxin is widespread, with the risk of aggregation outbreak. Therefore, it is an effective means to prevent and control the outbreak of food poisoning to strengthen the surveillance of diarrhoeal diseases and make full use of the national pathogen identification network to study the pathogen characteristics of isolated strains in this region.