Center for Food Safety, University of Georgiagrid.213876.9, Griffin, Georgia, USA.
Guangdong University of Technology, Guangzhou, Guangdong, China.
Appl Environ Microbiol. 2022 Nov 8;88(21):e0126922. doi: 10.1128/aem.01269-22. Epub 2022 Oct 13.
For decades, quaternary ammonium compounds (QAC)-based sanitizers have been broadly used in food processing environments to control foodborne pathogens such as Listeria monocytogenes. Still, there is a lack of consensus on the likelihood and implication of reduced susceptibility to benzalkonium chloride (BC) that may emerge due to sublethal exposure to the sanitizers in food processing environments. With a focus on fresh produce processing, we attempted to fill multiple data and evidence gaps surrounding the debate. We determined a strong correlation between tolerance phenotypes and known genetic determinants of BC tolerance with an extensive set of fresh produce isolates. We assessed BC selection on L. monocytogenes through a large-scale and source-structured genomic survey of 25,083 publicly available L. monocytogenes genomes from diverse sources in the United States. With the consideration of processing environment constraints, we monitored the temporal onset and duration of adaptive BC tolerance in both tolerant and sensitive isolates. Finally, we examined residual BC concentrations throughout a fresh produce processing facility at different time points during daily operation. While genomic evidence supports elevated BC selection and the recommendation for sanitizer rotation in the general context of food processing environments, it also suggests a marked variation in the occurrence and potential impact of the selection among different commodities and sectors. For the processing of fresh fruits and vegetables, we conclude that properly sanitized and cleaned facilities are less affected by BC selection and unlikely to provide conditions that are conducive for the emergence of adaptive BC tolerance in L. monocytogenes. Our study demonstrates an integrative approach to improve food safety assessment and control strategies in food processing environments through the collective leveraging of genomic surveys, laboratory assays, and processing facility sampling. In the example of assessing reduced susceptibility to a widely used sanitizer, this approach yielded multifaceted evidence that incorporates population genetic signals, experimental findings, and real-world constraints to help address a lasting debate of policy and practical importance.
几十年来，基于季铵盐化合物（QAC）的消毒剂已广泛用于食品加工环境中，以控制食源性病原体，如单核细胞增生李斯特菌。尽管如此，对于在食品加工环境中因亚致死暴露于消毒剂而可能出现的苄索氯铵（BC）敏感性降低的可能性和影响，仍缺乏共识。本研究重点关注新鲜农产品加工，我们试图填补有关这一争论的多个数据和证据空白。我们确定了在大量新鲜农产品分离株中，耐盐表型与已知的 BC 耐受力遗传决定因素之间存在很强的相关性。我们通过对美国各种来源的 25083 个公开可用的单核细胞增生李斯特菌基因组进行大规模、来源结构的基因组调查，评估了 L. monocytogenes 上的 BC 选择。考虑到加工环境的限制，我们监测了在耐受和敏感分离株中，适应性 BC 耐受的时间发生和持续时间。最后，我们在日常操作的不同时间点，在一个新鲜农产品加工设施中监测整个残留 BC 浓度。虽然基因组证据支持在一般食品加工环境中提高 BC 选择和推荐消毒剂轮换，但这也表明在不同商品和部门中，这种选择的发生和潜在影响存在明显差异。对于新鲜水果和蔬菜的加工，我们的结论是，经过适当消毒和清洁的设施受 BC 选择的影响较小，不太可能为 L. monocytogenes 适应性 BC 耐受的出现提供有利条件。我们的研究通过整合基因组调查、实验室检测和加工设施采样，展示了一种综合方法，以改善食品加工环境中的食品安全评估和控制策略。在评估对广泛使用的消毒剂的敏感性降低的示例中，这种方法提供了多方面的证据，其中包括群体遗传信号、实验发现和实际约束，以帮助解决具有政策和实际重要性的长期争论。
