Cortimiglia Claudia, Borney Maria Francesca, Bassi Daniela, Cocconcelli Pier Sandro
Dipartimento di Scienze e Tecnologie Alimentari per una Filiera Agro-Alimentare Sostenibile (DISTAS), Università Cattolica del Sacro Cuore, Piacenza, Italy.
Front Microbiol. 2021 Feb 1;11:629189. doi: 10.3389/fmicb.2020.629189. eCollection 2020.
Shiga-toxin-producing (STEC) represents a significant cause of foodborne disease. In the last years, an increasing number of STEC infections associated with the consumption of raw and pasteurized milk cheese have been reported, contributing to raise the public awareness. The aim of this study is to evaluate the main genomic features of STEC strains isolated from a semi-hard raw milk cheese, focusing on their pathogenic potential. The analysis of 75 cheese samples collected during the period between April 2019 and January 2020 led to the isolation of seven strains from four -positive enrichment. The genome investigation evidenced the persistence of two serotypes, O174:H2 and O116:H48. All strains carried at least one gene and were negative for gene. The virulence gene pattern was homogeneous among the serogroup/ST and included adherence factors (, , , , , , , and ), enterohemolysin (), serum resistance (, ), cytotoxin-encoding genes like and , and the Locus of Adhesion and Autoaggregation Pathogenicity Islands (LAA PAIs) typically found in Locus of Enterocyte Effacement (LEE)-negative STEC. Genome plasticity indicators, namely, prophagic sequences carrying genes and plasmid replicons, were detected, leading to the possibility to share virulence determinants with other strains. Overall, our work adds new knowledge on STEC monitoring in raw milk dairy products, underlining the fundamental role of whole genome sequencing (WGS) for typing these unknown isolates. Since, up to now, some details about STEC pathogenesis mechanism is lacking, the continuous monitoring in order to protect human health and increase knowledge about STEC genetic features becomes essential.
产志贺毒素大肠杆菌（STEC）是食源性疾病的一个重要病因。在过去几年中，与食用生乳和巴氏杀菌乳干酪相关的STEC感染报告数量不断增加，这提高了公众意识。本研究的目的是评估从一种半硬质生乳干酪中分离出的STEC菌株的主要基因组特征，重点关注其致病潜力。对2019年4月至2020年1月期间收集的75份奶酪样品进行分析，从四次阳性富集培养中分离出七株菌株。基因组研究证实了两种血清型O174:H2和O116:H48的存在。所有菌株至少携带一个 基因，且 基因检测为阴性。血清群/ST之间的毒力基因模式是一致的，包括黏附因子（ 、 、 、 、 、 、 、 ）、肠溶血素（ ）、血清抗性（ 、 ）、细胞毒素编码基因如 和 ，以及通常在肠细胞脱落位点（LEE）阴性的STEC中发现的黏附与自聚集致病岛（LAA PAIs）。检测到基因组可塑性指标，即携带 基因的前噬菌体序列和质粒复制子，这表明有可能与其他菌株共享毒力决定因素。总体而言，我们的工作为生乳乳制品中STEC监测增添了新知识，强调了全基因组测序（WGS）在鉴定这些未知分离株方面的重要作用。由于到目前为止，关于STEC致病机制的一些细节尚不清楚，为保护人类健康并增加对STEC遗传特征的了解而进行持续监测变得至关重要。
