一起O10:K4型副溶血弧菌食物中毒的病原学特征分析

Etiologic characteristics analysis of a case of food poisoning caused by O10:K4 Vibrio parahaemolyticus

目的 对北京市丰台区一起O10:K4型副溶血弧菌食物中毒进行病原学特征分析。方法 2021年10月10日北京市丰台区辖区哨点医院上送的食物中毒病例粪便标本共4件,标本编号为FTSY1~4。疾控中心现场处置共采集标本30件,其中食品标本13件、环境标本15件、餐厅用水2件。采用实时荧光PCR法和传统细菌分离鉴定法相结合的方式进行病原学鉴定。副溶血弧菌分离株采用玻片凝集法进行血清分型、PCR法检测毒力基因、微量肉汤稀释法进行药敏试验,选用SfiI酶进行脉冲场凝胶电泳(PFGE)实验,BioNumerics v6.0软件进行分子分型和聚类分析。采用全基因组测序(WGS)技术及CSIPhylogeny软件进行全基因组单核苷酸多态性分析(wgSNP)。结果 34件标本共分离出4株O10:K4型副溶血弧菌,均为临床分离株。4株菌均为产毒株,携带毒力基因tdh、T3SS1和T3SS2,不携带trh。4株菌对17种抗生素(氨苄西林、氨苄西林-舒巴坦、头孢噻肟、头孢他啶、头孢他啶/阿维巴坦、厄他培南、美罗培南、阿奇霉素、链霉素、阿米卡星、四环素、替加环素、氯霉素、萘啶酸、环丙沙星、复方新诺明、多粘菌素E)敏感,均携带bla_(CARB-22)基因。PFGE结果显示,4株菌带型完全一致,同源性为100%。WGS分析结果显示,4株菌属ST3序列型、CC3克隆群,为同一克隆。4株菌均携带大流行株标志基因tdh+、trh-、toxRS/new和orf8。结论 O10:K4型副溶血弧菌可引起食物中毒暴发,其致病性强,有产生耐药性和成为大流行株的可能。应进一步加强监测和分析,加强预防宣传和规范临床用药。

Objective To analyze the etiological characteristics of O10:K4 serotype Vibrio parahaemolyticus in a food poisoning case discovered in Fengtai district,Beijing.Methods On October 10 2021,a total of 4 fecal samples of food poisoning cases were went from Sentinel Hospital of Fengtai District,Beijing,with the specimen number FTSY1-4.A total of 30 samples were collected and disposed by CDC,including 13 food samples,15 environmental samples and 2 restaurant water samples.The pathogen was identified by the combination of real-time fluorescent PCR and traditional bacterial isolation.The Vibrio parahaemolyticus strains isolated were serotyped by slide agglutination method,tested for virulence gene tlh/tdh/trh by PCR,tested for antibiotic sensitivity by the method of micro-broth dilution.A pulsed-field gel electrophoresis(PFGE) molecular typing was performed using SfiI enzyme and cluster analysis was performed using BioNumerics v6.0 software.Whole genome single nucleotide polymorphism analysis(wgSNP)was performed using whole genome sequencing(WGS)technique and CSIPhylogeny software.Results There were 4 strains of O10:K4 serotype Vibrio parahaemolyticus were isolated;all of them were clinical isolates.The 4 strains were all toxin-producing strains,carrying virulence genes tdh,T3SS1 and T3SS2,but not trh.They were all susceptible to 17 antibiotics(Ampicillin,Ampicillin-sulbactam,Cefotaxime,Ceftazidime,Ceftazidime-avibactam,Ertapenem,Meropenem,Azithromycin,Streptomycin,Amikacin,Tetracycline,Tigecycline,Chloramphenicol,Nalidixic acid,Ciprofloxacin,Trimethoprim-sulfamethoxazole,Colistin)and carried bla_(CARB-22)gene.The results of PFGE showed that the 4 strains had identical banding patterns and 100% homology.The WGS analysis showed that all 4 strains were from the same clone,belonging to ST3 and CC3,and carrying the genes tdh+,trh-,toxRS/new and orf8.Conclusions O10:K4 serotype Vibrio parahaemolyticus would cause food poisoning outbreak,which has strong pathogenicity and has the possibility of drug resistance and becoming a pandemic strain.Monitoring and analysis should be further strengthened,and preventive propaganda and clinical medication should be strengthened.