一起鼠伤寒沙门菌引起食物中毒的病原鉴定与同源性分析

Pathogenic identification and homological analysis in a food poisoning incident caused by Salmonella typhimurium

目的对引起本次食物中毒主要病原菌鼠伤寒沙门菌进行生物学鉴定,血清学分型以及分子的溯源分析,研究分析其相关性,从而达到准确溯源的目的。方法对3份患者肛拭子样本和1份食品样本分离到的沙门菌进行菌株鉴定,采用美国临床实验室标准化研究所CLSI标准推荐微量肉汤稀释法,对分离株进行15种抗生素敏感实验,利用限制性内切酶Xba I酶切沙门菌基因组进行脉冲场凝胶电泳,通过Bio Numerics 6.6软件对电泳图谱进行同源性比较。结果3份患者样本和1份食品留样中共检出鼠伤寒沙门菌4株,均对氨苄西林、四环素、红霉素耐药。运用PFGE对所分离到的鼠伤寒沙门菌进行基因分型,其PFGE图谱相似性系数为100%。结论本次食源性疾病暴发疫情是由进食被鼠伤寒沙门菌污染的食品所致,通过PFGE对致病菌进行溯源,分析其溯源关系,能追踪到菌株来源,PFGE可有效应用于食物中毒溯源分析及分子流行病学研究。

Objective To identify the main pathogenic bacteria of Salmonella typhimurium in food by the biological identification,serotyping and molecular traceability,and to analyze its relevance,so as to achieve accurate traceability. Methods Salmonella typhimurium isolated from 3 anal samples from patients and 1 food residue sample were analyzed for pathogen identification. According to the recommendation of CLSI standards by the Clinical and Laboratory Standard Institute,broth microdilution method was used to determine the susceptibility of 15 isolates to antibiotics. The Salmonella genome which was cleavaged by restriction enzyme Xba1 were carried out by pulsed-field gel electrophoresis. The PFGE fingerprint was conducted for homological comparison by the software Bionumerics 6. 6. Results A total of 4 strains of Salmonella typhimurium were isolated from samples of 3 patients and 1 food residue sample. All isolates were resistant to Ampicillin,Tetracycline,Erythromycin. The similarity coefficient of 4 isolates was 100% by PFGE. Conclusion The food poisoning incident was caused by consumption of Salmonella typhimurium contaminated food. Traceability was conducted on the pathogenic bacteria through PFGE to analyze its traceability relationship,which traced the source of strain. PFGE can be effectively used in food poisoning source analysis and molecular epidemiological study.