一起空肠弯曲菌导致急性胃肠炎暴发事件的病原特征分析

目的 对一起急性胃肠炎暴发事件进行实验室检测分析。方法 对暴发事件中采集的病例粪便标本、厨师粪便标本、环境涂抹、食品原材料等样本进行实时荧光定量PCR检测和细菌分离培养分析。对分离菌株进行PFGE分型分析并对病例分离株进行抗生素敏感性检测和全基因组测序分析。结果 4例病例粪便标本空肠弯曲菌核酸检测阳性，其中1例未服用抗生素的病例分离到空肠弯曲菌；从4份生鸡样本中获得12个空肠弯曲菌单菌落和7个结肠弯曲菌单菌落。病例分离株对萘啶酸、环丙沙星、氯霉素、氟苯尼考和四环素耐药；基因组测序分析确定该菌株为ST10075型，并确定其染色体上含有cmeABCR、tetO/M和blaOXA-61等耐药元件，而23S rRNA的2 074和2 075位点均未发生突变，gyrA基因的257位点发生了C-T的突变。结论 实验室检测结果表明空肠弯曲菌的感染可能是导致此次急性胃肠炎暴发的主要病原。

Laboratory investigation for one gastroenteritis outbreak caused by Campylobacter jejuni

Objective To understand the etiological characteristics of an acute gastroenteritis outbreak. Methods Real-time polymerase chain reaction (PCR) and bacteria cultures were performed for the samples, including stool samples from patients and cooks, environmental swabs, raw food material (chicken meat), collected during the outbreak. Pulsed-field gel electrophoresis, antibiotics susceptibility test and whole-genome sequencing were performed for the Campylobacter jejuni isolates. Results Four stool samples from patients were positive for Campylobacter jejuni by real-time PCR, in which 1 Campylobacter jejuni strain was isolated from a case who had no antibiotic treatment. Twelve Campylobacter jejuni and 7 Campylobacter coli isolates were obtained from 4 raw chicken meat samples. The Campylobacter jejuni strain isolated from the case was resistant to nalidixic acid, ciprofloxacin, chloramphenicol, florfenicol and tetracycline. The MLST analysis with the whole-genome sequences confirmed that the Campylobacter jejuni isolate from the case belonged to ST10075. Antimicrobial resistance genes cmeABCR, tetO/M and blaOXA-61 were found in the genome of the isolate from the patient by the whole-genome sequencing. No mutation in 23S rRNA was found and the C257T mutation in gyrA was identified in this isolate. Conclusion Laboratory analysis indicated that Campylobacter jejuni infection might be the major cause of this gastroenteritis outbreak.