产气荚膜梭菌污染牛肉的溯源及传播规律分析

Tracing contamination and transmission routes of Clostridium perfringens on beef

应用脉冲场凝胶电泳(pulsed field gel electrophoresis,PFGE)对从陕西省的3个屠宰场(Ⅰ~Ⅲ场)以及内蒙古的1个屠宰场(Ⅳ场)采集的牛屠宰、分割过程中各环节的样品分离到的138株产气荚膜梭菌(Clostridimn perfringens,C.perfringens)分离菌株进行基因型区分,通过BioNumerics软件进行条带的识别并对结果进行分析。结果显示,菌株相似度为39.9%~100%,相似度≥50%时可分为15个分支,相似度≥90%时可分为114个基因型;Ⅰ场共55株菌分为50个PFGE基因型,Ⅱ场共36株菌分21个型,Ⅲ场共42株菌分40个型,Ⅳ场共5株菌分4个型;相同PFGE型的相同毒素基因型概率为69%,分离菌株具有遗传多样性和流行相关性;牛肉中的分离菌可追溯至分割环节的工具或人员样品及屠宰环节的粪便、皮毛和空气,粪便及体表携带的菌在屠宰过程中污染胴体,随后进入分割环节,肉样与工具之间交叉污染进一步造成牛肉污染为该菌的传播途径,剥皮和刀具是C.perfringens污染的关键控制点。结果表明,C.perfringens突破屠宰环节的细菌防控屏障污染牛肉,因此,必须严格监控牛屠宰分割过程造成交叉污染的关键控制点降低该菌污染牛肉和感染消费者的风险。

Pulsed field gel electrophoresis(PFGE)was used to analyze 138strains of C.perfringens isolated from the slaughter and butchering process from 3slaughterhouses in Shaanxi Province and 1slaughterhouse in Inner Mongolia,the bands were identified by BioNumerics software and analysis results.The results showed that the similarity of all isolates was ranged from 39.9%to 100%,divided into 15branches according to the similarity≥50%and 114PFGE genotypes with the similarity≥90%.55isolates were divided into 50PFGE genotypes from groundⅠ,36 isolates were divided into 21genotypes from groundⅡ,42isolates into 40genotypes from groundⅢ,5isolates were divided into 4genotypes from groundⅣ.It was showed that the genetic diversity and epidemic correlation,with a 69%probability of the same toxin type when PFGE genotype was the same.The isolates from beef could be traced to tools or personnel of the cutting stage,as well as feces,hides and air of the slaughtering stage.The transmission route of the bacterium was speculated that the carcass was contaminated by the feces and hides of the slaughtered cattle during the slaughtering process,further beef cross-contaminated by meat and meet as well as meat and tools in the butchering process,with peeling and cutting knives of key control points for C.perfringens contamination during the whole process.C.perfringens breaks through bacterial control barrier of the slaughterhouse and contaminates the beef,posing a threat to consumer health.Therefore,it is necessary to monitor the key control points of cross-contamination strictly in the cattle slaughtering and butchering process to reduce the risk of beef contamination and the threaten of consumer infection by C.perfringens.