一起副溶血性弧菌食物中毒分离株的特征分析

Etiological analysis of a small outbreak of gastroenteritis with Vibrio parahaemolyticus infection

目的分析2017年广州市一起副溶血性弧菌食物中毒分离株的特征。方法采用血清型鉴定,药敏实验,毒力基因(tdh、trh、tlh)、toxRS/new基因、orf8基因的聚合酶链式反应(PCR)检测,脉冲场凝胶电泳(PFGE)和多位点序列分型(MLST)进行分析。结果 14株副溶血性弧菌血清型鉴定为O8∶K21,药敏试验显示14株菌对氨苄西林、甲氧苄氨嘧啶耐药,对头孢曲松、环丙沙星、氯霉素、磺胺甲口恶唑/甲氧苄啶、磺胺复合物、阿米卡星、萘啶酸、链霉素、四环素、庆大霉素敏感。毒力基因全部为tdh+tlh+trh-,均携带toxRS/new和orf8基因。经PFGE聚类分析,14株判断为高度相关株。经MLST分析,结果全部为ST479型。结论引起此次食物中毒的病原菌是副溶血性弧菌O8∶K21型,彼此具有共同的遗传特征,携带大流行克隆株的标志性基因,应进一步加强对此类菌株的监测和控制。

Objective To investigate the etiology of a small outbreak of gastroenteritis caused by Vibrio parahaemolyticus in Guangzhou, 2017. Methods Serotype identification, antimicrobial susceptibility test, polymerase chain reaction(PCR) test of virulence genes(tdh, trh, tlh), toxRS/new gene, orf8 gene, pulsed field gel electrophoresis(PFGE) and multilocus sequence typing(MLST) were analyzed. Results The serotype O8∶K21 was identified. All isolates were sensitive to ceftriaxone, ciprofloxacin, chloramphenicol, cotrimoxazole, sulfonamide complex, amikacin, nalidixic acid, streptomycin, tetracycline and gentamicin, and resistant to ampicillin and trimethoprim. The PCR detection of virulence gene showed that all the strains were positive for tdh(thermostable direct hemolysin) and tlh(themolabile hemolysin), but negative for trh(tdh-related hemolysin), and carried toxRS/new and orf8 genes. According to PFGE cluster analysis, they were considered to be a highly related strains. According to MLST analysis, the results were all ST479 type. Conclusion The reason for the small outbreak of gastroenteritis was due to Vibrio parahaemolyticus O8∶K21, which shared common genetic characteristics. It harbored the tdh gene which was the key characteristic of pandemic strains, and additional surveillance should be conducted to facilitate control of the transmission of this pathogen.