Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853; Food Safety Laboratory, Department of Food Science, Cornell University, Ithaca, NY 14853.
Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853.
J Dairy Sci. 2024 Nov;107(11):9036-9053. doi: 10.3168/jds.2024-24789. Epub 2024 Jul 14.
Farmstead dairy processing facilities may be particularly susceptible to Listeria spp. contamination due to the close physical proximity of their processing environments (PE) to associated dairy farm environments (FE). In this case study, we supported the implementation of interventions focused on improving (1) cleaning and sanitation efficacy, (2) hygienic zoning, and (3) sanitary equipment and facility design and maintenance in a farmstead dairy processing facility, and evaluated their effect on Listeria spp. detection in the farmstead's PE over 1 yr. Detection of Listeria spp. in the farmstead's PE was numerically reduced from 50% to 7.5% after 1 yr of intervention implementation, suggesting that these interventions were effective at improving Listeria spp. control. In addition, environmental samples were also collected from the farmstead's FE to evaluate the risk of the FE as a potential source of Listeria spp. in the PE. Overall, detection of Listeria spp. was higher in samples collected from the FE (75%, 27/36) compared with samples collected from the PE (24%, 29/120). Whole-genome sequencing performed on select isolates collected from the PE and FE supported the identification of 6 clusters (range of 3 to 15 isolates per cluster) that showed ≤ 50 high-quality single nucleotide polymorphism differences. Of these 6 clusters, 3 (i.e., clusters 2, 4, and 5) contained isolates that were collected from both the PE and FE, suggesting that transmission between these 2 environments was likely. Moreover, all cluster 2 isolates represented a clonal complex of L. monocytogenes commonly associated with dairy farm environmental reservoirs (i.e., CC666), which may support that the farmstead's FE represented an upstream source of the cluster 2 isolates that were found in the PE. Overall, our data underscore that although the FE can represent a potential upstream source of Listeria spp. contamination in a farmstead dairy processing facility, implementation of targeted interventions can help effectively minimize Listeria spp. contamination in the PE.
牧场奶制品加工设施由于其加工环境 (PE) 与相关奶牛场环境 (FE) 紧密相邻，因此特别容易受到李斯特菌属的污染。在本案例研究中，我们支持实施干预措施，重点是改善 (1) 清洁和卫生效果、(2) 卫生分区以及 (3) 卫生设备和设施设计和维护，在一个牧场奶制品加工设施中，并在 1 年内评估它们对牧场 PE 中李斯特菌属检测的影响。在干预实施 1 年后，牧场的 PE 中李斯特菌属的检测数量从 50%减少到 7.5%，表明这些干预措施在改善李斯特菌属控制方面是有效的。此外，还从牧场的 FE 收集环境样本，以评估 FE 作为 PE 中李斯特菌属潜在来源的风险。总体而言，与从 PE 收集的样本 (24%，29/120) 相比，从 FE 收集的样本中李斯特菌属的检测率更高 (75%，27/36)。从 PE 和 FE 收集的选定分离株进行的全基因组测序支持了 6 个聚类的鉴定 (每个聚类 3 至 15 个分离株)，这些聚类显示 ≤ 50 个高质量单核苷酸多态性差异。在这 6 个聚类中，有 3 个 (即聚类 2、4 和 5) 包含从 PE 和 FE 收集的分离株，这表明这两个环境之间可能存在传播。此外，所有聚类 2 分离株均代表与奶牛场环境储库相关的单核细胞增生李斯特菌属的一个克隆复合体 (即 CC666)，这可能支持农场的 FE 代表在 PE 中发现的聚类 2 分离株的上游来源。总的来说，我们的数据强调，尽管 FE 可能是牧场奶制品加工设施中李斯特菌属污染的潜在上游来源，但实施有针对性的干预措施可以帮助有效减少 PE 中的李斯特菌属污染。
