PDF(Pubmed)
Abstract：
Listeria monocytogenes is the etiologic agent of listeriosis, a foodborne disease that poses a threat to public health globally. Chicken meat exhibits heightened susceptibility to L. monocytogenes contamination during butchery. The persistence of this pathogen in the slaughterhouse environment enables recurring contamination of meat products. This study aimed at identifying the sources and transmission routes of L. monocytogenes contamination within an abattoir where it was consistently detected for three consecutive years (2019-2021). Furthermore, the environmental factors aiding contamination along chicken processing lines were determined by surveying the microbiome within the facility. Samples collected in 2019 to 2021 were subjected to culture-dependent analysis to assess the prevalence, serotypes, and multi-locus sequence typing (MLST) of L. monocytogenes. Additionally, the specimens collected in 2021 underwent culture-independent analysis via real-time quantitative polymerase chain reaction (qPCR) and 16S rRNA gene amplicon sequencing to identify the contamination sources and characterize the entire microbial community within the slaughterhouse. L. monocytogenes was isolated only from the clean zone, where the final slaughtering stage occurs. Most strains isolated from the final carcasses showed the same genetic cluster as the isolate in the chilling water and were assigned to MLST profile ST3. Culture-independent qPCR confirmed L. monocytogenes contamination in all samples, excluding post-scalding carcasses, prewashed post-evisceration carcasses, and the bleeding areas. Consequently, qPCR enabled more comprehensive identification of L. monocytogenes contamination points than culture-dependent approaches. Moreover, 16S rRNA gene amplicon sequencing demonstrated that psychro-tolerant and spoilage-related bacteria with L. monocytogenes-like attributes exhibited enhanced viability in the clean zone and immersion-chilling water. Metagenomics-based source tracking analysis further revealed that the shackles and chilling waters represent predominant sources of cross-contamination between different slaughterhouse zones, whereas the grading and packaging workstations and chilling water in the clean zone were deemed crucial sources affecting final carcass contamination. Collectively, these findings demonstrate through culture-dependent and -independent methods that L. monocytogenes spreads along the slaughter line, contaminating the slaughterhouse. Moreover, by investigating changes in microbial community and bacterial flow along the slaughter line within the facility, the sources influencing carcass contamination can be effectively traced.
摘要：
单核细胞增生李斯特菌是李斯特菌病的病原体，一种对全球公共卫生构成威胁的食源性疾病。在屠宰过程中，鸡肉对单核细胞增生李斯特菌污染的敏感性更高。这种病原体在屠宰场环境中的持续存在使得肉制品受到反复污染。这项研究旨在确定屠宰场内单核细胞增生李斯特菌污染的来源和传播途径，该屠宰场连续三年(2019-2021年)被检测到。此外，通过调查设施内的微生物组，确定了导致鸡肉加工线污染的环境因素。2019年至2021年收集的样本进行了文化依赖性分析，以评估患病率，血清型,和单核细胞增生李斯特菌的多位点序列分型（MLST）。此外,通过实时定量聚合酶链反应(qPCR)和16SrRNA基因扩增子测序,对2021年收集的标本进行了培养无关性分析,以确定污染源并表征屠宰场内整个微生物群落.单核细胞增生李斯特菌只从干净的区域分离，最后的屠宰阶段。从最终car体中分离出的大多数菌株显示出与冷水中分离出的菌株相同的遗传簇，并被分配给MLST谱ST3。不依赖培养的qPCR证实了所有样品中的单核细胞增生李斯特菌污染，不包括烫伤后的尸体，预洗后的内脏尸体，和出血区域。因此,与依赖培养的方法相比，qPCR能够更全面地鉴定单核细胞增生李斯特菌的污染点。此外，16SrRNA基因扩增子测序表明，具有单核细胞增生李斯特菌样属性的耐霉菌和腐败相关细菌在清洁区和浸泡冷水中的生存力增强。基于宏基因组学的来源跟踪分析进一步表明，束缚和冷水代表了不同屠宰场区域之间交叉污染的主要来源，而清洁区的分级和包装工作站和冷却水被认为是影响最终car体污染的关键来源。总的来说，这些发现表明，通过培养依赖性和非依赖性方法，单核细胞增生李斯特菌沿屠宰线传播，污染屠宰场.此外，通过调查设施内屠宰线上微生物群落和细菌流动的变化，可以有效追踪影响car体污染的来源。
