CSIRO Agriculture and Food, Coopers Plains, QLD, Australia; CSIRO Agriculture and Food, Werribee, VIC, Australia; Food Safety Centre, Tasmanian Institute of Agriculture, School of Land and Food, University of Tasmania, Hobart, TAS, Australia.
CSIRO Agriculture and Food, Werribee, VIC, Australia.
Int J Food Microbiol. 2021 Jul 16;350:109247. doi: 10.1016/j.ijfoodmicro.2021.109247. Epub 2021 May 17.
The ability of Listeria monocytogenes isolates to survive within the food production environment (FPE), as well as virulence, varies greatly between strains. There are specific genetic determinants that have been identified which can strongly influence a strains ability to survive in the FPE and/or within human hosts. In this study, we assessed the FPE fitness and virulence potential, including efficacy of selected hygiene or treatment intervention, against 52 L. monocytogenes strains isolated from various food and food environment sources. Phenotypic tests were performed to determine the minimum inhibitory concentration of cadmium chloride and benzalkonium chloride and the sensitivities to five clinically relevant antibiotics. A genomic analysis was also performed to identify resistance genes correlating to the observed phenotypic resistance profiles, along with genetic determinants of interest which may elude to the FPE fitness and virulence potential. A transposon element containing a novel cadmium resistance gene, cadA7, a Tn916 variant insert in the hypervariable Listeria genomic island 1 region and an LGI2 variant were identified. Resistance to cadmium and disinfectants was prevalent among isolates in this study, although no resistance to clinically important antimicrobials was observed. Potential hypervirulent strains containing full length inlA, LIPI-1 and LIPI-3 were also identified in this study. Cumulatively, the results of this study show a vast array of FPE survival and pathogenicity potential among food production-associated isolates, which may be of concern for food processing operators and clinicians regarding L. monocytogenes strains colonising and persisting within the FPE, and subsequently contaminating food products then causing disease in at risk population groups.
单核细胞增生李斯特菌分离株在食品生产环境（FPE）中生存的能力，以及其毒力，在菌株之间差异很大。已经确定了特定的遗传决定因素，这些因素可以强烈影响菌株在 FPE 中生存的能力和/或在人类宿主中的生存能力。在这项研究中，我们评估了 52 株从各种食品和食品环境来源分离的单核细胞增生李斯特菌的 FPE 适应性和毒力潜力，包括针对所选卫生或治疗干预措施的效果。进行了表型测试，以确定氯化镉和苯扎氯铵的最小抑菌浓度以及对五种临床相关抗生素的敏感性。还进行了基因组分析，以确定与观察到的表型耐药谱相关的耐药基因，以及可能逃避 FPE 适应性和毒力潜力的感兴趣的遗传决定因素。鉴定出一种含有新型镉抗性基因 cadA7 的转座子元件、在高变异性李斯特菌基因组岛 1 区的 Tn916 变体插入物和 LGI2 变体。尽管未观察到对临床重要抗菌药物的耐药性，但本研究中分离株对镉和消毒剂的耐药性很普遍。本研究还鉴定出含有全长 inlA、LIPI-1 和 LIPI-3 的潜在高毒力菌株。总的来说，这项研究的结果表明，在与食品生产相关的分离株中存在广泛的 FPE 生存和致病性潜力，这可能引起食品加工操作人员和临床医生的关注，因为李斯特菌菌株在 FPE 中定植和持续存在，并随后污染食品产品，然后导致高危人群患病。
