肉牛屠宰过程中分离出沙门氏菌的FAFLP分子溯源分析

为确定沙门氏菌在宰前、屠宰过程中的污染情况,明确沙门氏菌在厂内发生污染的主要环节,为工厂中沙门氏菌的控制提供数据支持,本研究采用荧光扩增长度多态性(FAFLP)的方法对屠宰过程中7个工序分离出的7种不同血清型共计83株沙门氏菌进行分子分型。结果显示83株沙门氏菌在0.83的相似度下划分为6个大群,与血清型呈现一定的联系。以0.86的相似度进行溯源,发现FAFLP较血清分型具备更高的灵敏度,与前期的流行率的调查数据吻合。溯源结果表明沙门氏菌在肉牛皮毛、粪便中存在较为严重的交叉污染现象,同时部分粪便、皮毛分离出的沙门氏菌穿过了屠宰企业的防控屏障,对工厂内部的胴体造成了污染。肉牛屠宰加工企业应注重宰前动物的规范化管理,减少宰前交叉污染对工厂内部干预措施的压力,同时应增加必要的危害控制点,以降低沙门氏菌检出的风险。

Molecular Typing of Salmonella Species Isolated from Beef in a Processing Plant with Fluorescence Amplified Fragment Length Polymorphism

Fluorescence amplified fragment length polymorphism (FAFLP) analysis was used for molecular typing of 83 Salmonella strains in seven different serotypes isolated from seven different processing points, in order to investigate the contamination of Salmonella before and during slaughtering, to specify the main steps involving the contamination of Salmonella within the processing plant, and to provide data for the control of Salmonella infection within the plant.. The results showed that the 83 strains were divided into three groups at the similarity of 0.83, and a certain correlation was observed between the FAFLP gene types and the serotypes. When source tracing was conducted at the similarity of 0.86, FAFLP exhibited a higher sensitivity than traditional serotyping, and the result was consistent with the previous data on the prevalence rate obtained from a previous epidemiological investigation. The source tracing analysis showed a serious cross-contamination of Salmonella among animals, which occurred through the feces and fur. Furthermore, some Salmonella strains isolated from the feces and fur crossed the protective barrier of the processing plants and infected the downstream carcasses. Hence, processing plants should pay more attention to standardized pre-slaughter management strategies to avoid the cross-contamination problems during in-plant interventions. Additionally, in-plant interventions should include extra critical control points to reduce the risk of Salmonella infection.