一起由空肠弯曲菌所致食源性疾病暴发事件的流行病学及病原学溯源分析

Epidemiology and etiology tracing analysis of an outbreak of Campylobacter jejuni foodborne disease

目的对一起空肠弯曲菌所致的食源性疾病暴发事件进行流行病学及溯源分析。方法对突发事件进行现场流行病学调查,采集粪便样本、环境涂抹样本、食品样本等进行快速PCR检测和病原菌分离。对分离菌株进行PFGE分子分型和全基因组测序分析,并进行药敏试验。结果从7份病例样本和2份环境涂抹样本中分离出空肠弯曲菌。PFGE分析和cgMLST聚类结果表明其中3份病例样本和环境涂抹样本(蒸柜容器把手涂抹)分离的菌株克隆聚集成簇,ST型别为ST11105;另2份病例样本和环境涂抹样本(刀具砧板涂抹)分离的菌株属同一克隆株,ST型别为ST2031。还有2份病例样本分离的菌株ST型为ST11106和ST7533。药敏结果表明,分离株对四环素类和喹诺酮类耐药率较高,分别为77.8%、55.6%。基因组测序结果发现最多的耐药基因为bla_(OXA-193),gyrA、tet(O),其中gyrA基因86位点发生T-I突变。分离株共获得168个毒力基因,涉及多种致病机理。结论采用快速PCR法、PFGE分子分型技术、全基因组测序技术等可对突发事件进行快速、准确的溯源分析。

This study performed epidemiology and etiology tracing analysis of an outbreak of Campylobacter jejuni foodborne disease.Field epidemiological investigation was performed for this disease outbreak.Fecal,environmental,and food samples were collected for rapid PCR detection and strain separation.Strains were analyzed with pulsed field gel electrophoresis(PFGE),whole genome sequencing(WGS)and antimicrobial susceptibility testing.Nine Campylobacter jejuni strains were isolated,including seven strains from fecal samples and two strains from environmental samples.PFGE analysis and cg-MLST analysis showed that three strains from fecal samples and a strain from a steamer handle were the same cloning strains,and two strains from fecal samples and a strain from a cutting board surface were the same cloning strains.Moreover,the two main sequencing types(STs)were ST11105 and ST2031,and the STs of two other strains from fecal samples were ST11106 and ST7533.Nearly all strains were resistant to tetracycline(77.8%)and quinolones(55.6%).WGS analysis indicated that the most common resistance genes were OXA-193,tet(O)and gyr A,with a C-T mutation at gene locus 86.Additionally,168 virulence genes were discovered in these nine isolates and were found to involve a variety of pathogenic mechanisms.In conclusion,this outbreak of foodborne disease was caused by several different genotypes of Campylobacter jejuni.Tracing analyzed was performed quickly and accurately through rapid PCR detection,PFGE,and WGS.