食源性病原体单核细胞增生李斯特菌可以在生产加工环境中持续存在,这增加了食品污染的风险。对常用于清洁和消毒程序的抗菌药物的耐药性增加可能有助于单核细胞增生李斯特菌在这些环境中的持久性。本研究旨在评估在包装季节2020-2021(Y1)和2021-2022(Y2)期间从三个树木水果包装设施(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来评估持久性的证据。使用肉汤微量稀释测定法,测试了2020-2022年收集的单核细胞增生李斯特菌分离株(n=44)对过氧乙酸(PAA)和专有生物膜去除剂的抗性。Further,对单核细胞增生李斯特菌分离株进行全基因组测序,筛选是否存在抗菌素耐药性和毒力基因,以及使用CFSANSNP生物信息学管道评估分离株的基因组相似性。超过一半(57%)的测试分离物具有250ppm的PAA最小抑制浓度(MIC),这与三个设施中PAA消毒剂的应用浓度(230ppm)相似。相比之下,80%的测试分离物的生物膜去除剂MIC为0.13ppm,大大低于设施中应用的浓度(137ppm)。所有测试分离株的基因组都具有抗菌素耐药性(fosX,林,mdrL,mprF,和norB)和毒力(inlA,inlb,plcA,plcB,prfa,hly,mpl,和iap)基因。在2020-2022年之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,具有22种多位点序列类型(MLST),属于22种不同的克隆复合物。与2016-2017年从同一设施收集的历史分离株的基因组相似性分析表明,F2中的基因型ST1003和ST554持续了5年,在2022年不再检测到。总的来说,我们的研究结果突出表明,需要重新评估消毒剂浓度,以有效控制树果实包装设施中的持久性单核细胞增生李斯特菌菌株.
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 2020-2022 belonged to three distinct lineages, with 22 multilocus sequence types (MLST) 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.