PDF(Pubmed)
Abstract：
Listeria monocytogenes is a foodborne pathogen of concern in dairy processing facilities, with the potential to cause human illness and trigger regulatory actions if found in the product. Monitoring for Listeria spp. through environmental sampling is recommended to prevent establishment of these microorganisms in dairy processing environments, thereby reducing the risk of product contamination. To inform on L. monocytogenes diversity and transmission, we analyzed genome sequences of L. monocytogenes strains (n = 88) obtained through the British Columbia Dairy Inspection Program. Strains were recovered from five different dairy processing facilities over a 10 year period (2007-2017). Analysis of whole genome sequences (WGS) grouped the isolates into nine sequence types and 11 cgMLST types (CT). The majority of isolates (93%) belonged to lineage II. Within each CT, single nucleotide polymorphism (SNP) differences ranged from 0 to 237 between isolates. A highly similar (0-16 SNPs) cluster of over 60 isolates, collected over 9 years within one facility (#71), was identified suggesting a possible persistent population. Analyses of genome content revealed a low frequency of genes associated with stress tolerance, with the exception of widely disseminated cadmium resistance genes cadA1 and cadA2. The distribution of virulence genes and mutations within internalin genes varied across the isolates and facilities. Further studies are needed to elucidate their phenotypic effect on pathogenicity and stress response. These findings demonstrate the diversity of L. monocytogenes isolates across dairy facilities in the same region. Findings also showed the utility of using WGS to discern potential persistence events within a single facility over time.
摘要：
单核细胞增生李斯特菌是乳制品加工设施中令人关注的食源性病原体，如果在产品中发现，有可能导致人类疾病并引发监管行动。李斯特菌的监测。建议通过环境采样来防止这些微生物在乳制品加工环境中的建立，从而降低产品污染的风险。为了告知单核细胞增生李斯特菌的多样性和传播，我们分析了通过不列颠哥伦比亚省乳品检验计划获得的单核细胞增生李斯特菌菌株（n=88）的基因组序列。在10年期间（2007-2017年），从五个不同的乳制品加工设施中回收了菌株。全基因组序列（WGS）的分析将分离株分为9种序列类型和11种cgMLST类型（CT）。大多数分离株（93％）属于谱系II。在每个CT中，分离株之间的单核苷酸多态性（SNP）差异在0到237之间。超过60个分离株的高度相似（0-16个SNP）簇，在一个设施内收集超过9年(#71)，被确定为可能的持续种群。基因组含量的分析表明，与胁迫耐受性相关的基因频率较低，除广为传播的镉抗性基因cadA1和cadA2外。在分离株和设施中，毒力基因和内在蛋白基因内突变的分布各不相同。需要进一步的研究来阐明它们对致病性和应激反应的表型影响。这些发现证明了同一地区乳制品设施中单核细胞增生李斯特菌分离株的多样性。研究结果还表明，随着时间的推移，使用WGS来辨别单个设施内潜在的持久性事件。
