Department of Food Science, The Pennsylvania State University, University Park, PA 16802, United States.
Division of Laboratory Services, Kentucky Department of Public Health, Frankfort, KY 40601, United States.
J Food Prot. 2024 Oct;87(10):100354. doi: 10.1016/j.jfp.2024.100354. Epub 2024 Aug 30.
The foodborne pathogen Listeria monocytogenes can persist in produce processing environments, which increases the risk for food contamination. Increased resistance to antimicrobials commonly used in cleaning and sanitizing procedures may contribute to L. monocytogenes' persistence in these environments. This study aimed to evaluate sanitizer resistance in L. monocytogenes isolates collected from three tree fruit packing facilities (F1, F2, and F3) during packing seasons 2020-2021 (Y1) and 2021-2022 (Y2), and to assess evidence of persistence based on the genomic similarity of isolates to historical isolates collected in previous years. L. monocytogenes isolates collected in 2020-2022 (n = 44) were tested for resistance to peroxyacetic acid (PAA) and a proprietary biofilm-removing agent using a broth microdilution assay. Further, L. monocytogenes isolates were whole genome sequenced and screened for the presence of antimicrobial resistance and virulence genes, as well as to assess the genomic similarity of isolates using the CFSAN SNP bioinformatic pipeline. Over half (57%) of the tested isolates had a PAA minimum inhibitory concentration (MIC) of 250 ppm, which was similar to the applied concentration of the PAA sanitizer in the three facilities (230 ppm). In contrast, 80% of tested isolates had a biofilm remover MIC of 0.13 ppm, which was substantially below the concentration applied in the facilities (137 ppm). Genomes of all tested isolates carried antimicrobial resistance (fosX, lin, mdrL, mprF, and norB) and virulence (inlA, inlB, plcA, plcB, prfA, hly, mpl, and iap) genes. L. monocytogenes isolates collected between 2020 and 2022 belonged to three distinct lineages, with 22 multilocus sequence types (MLSTs) belonging to 22 different clonal complexes. Genomic similarity analysis with historical isolates collected from the same facilities in 2016-2017 demonstrated a 5-year persistence of the genotypes ST 1003 and ST 554 in F2, which were no longer detected in 2022. Overall, our results highlight the need to re-evaluate sanitizer concentrations to effectively control persistent L. monocytogenes strains in tree fruit packing facilities.
食源性病原体单核细胞增生李斯特菌可以在农产品加工环境中存活，从而增加了食品污染的风险。在这些环境中，对抗生素清洁和消毒程序中常用的抗生素的抵抗力增加可能导致单核细胞增生李斯特菌的持续存在。本研究旨在评估 2020-2021 年（Y1）和 2021-2022 年（Y2）包装季节期间从三个水果包装厂（F1、F2 和 F3）收集的单核细胞增生李斯特菌分离株的消毒剂抗性，并根据分离株与前几年收集的历史分离株的基因组相似性评估其持久性的证据。使用肉汤微量稀释法检测 2020-2022 年收集的单核细胞增生李斯特菌分离株对过氧乙酸（PAA）和专有生物膜去除剂的抗性。此外，对单核细胞增生李斯特菌分离株进行全基因组测序，并筛选抗生素耐药性和毒力基因的存在情况，以及使用 CFSAN SNP 生物信息学管道评估分离株的基因组相似性。超过一半（57%）的测试分离株的 PAA 最小抑菌浓度（MIC）为 250ppm，与三个设施中应用的 PAA 消毒剂浓度相似（230ppm）。相比之下，80%的测试分离株的生物膜去除剂 MIC 为 0.13ppm，远低于设施中应用的浓度（137ppm）。所有测试分离株的基因组均携带抗生素耐药性（fosX、lin、mdrL、mprF 和 norB）和毒力（inlA、inlB、plcA、plcB、prfA、hly、mpl 和 iap）基因。2020 年至 2022 年间收集的单核细胞增生李斯特菌分离株属于三个不同的谱系，其中 22 个多位点序列型（MLST）属于 22 个不同的克隆复合体。与 2016-2017 年从同一设施收集的历史分离株进行基因组相似性分析表明，F2 中 ST1003 和 ST554 基因型的 5 年持久性，2022 年不再检测到。总体而言，我们的研究结果强调需要重新评估消毒剂浓度，以有效控制水果包装厂中持续存在的单核细胞增生李斯特菌菌株。
