Douëllou T, Delannoy S, Ganet S, Fach P, Loukiadis E, Montel M-C, Sergentet-Thevenot D
Institute National de Recherche Agronomique, Unité de Recherches Fromagères, 15000 Aurillac, France; Université de Lyon, Research Group "Bacterial Opportunistic Pathogens and Environment", UMR5557 Ecologie Microbienne Lyon, Université Lyon 1, CNRS, VetAgro Sup, 69280 Marcy l'Etoile, France.
Université Paris-Est, ANSES, Laboratoire de Sécurité des Aliments, Plateforme IdentyPath, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort, France.
Int J Food Microbiol. 2017 Jul 17;253:59-65. doi: 10.1016/j.ijfoodmicro.2017.04.010. Epub 2017 Apr 21.
Pathogenic Shiga toxin-producing E. coli (STEC) are recognized worldwide as environment and foodborne pathogens which can be transmitted by ingestion of ready-to-eat food such as raw milk-derived products. STEC show a prevalence rate in dairy products of 0.9%, yet comparably few outbreaks have been related to dairy products consumption. In this study, we used rt-qPCR to identify the virulence potential of O157, O26 and O103 STEC strains isolated from raw-milk dairy products by analyzing virulence-related gene frequencies and associations with O-island (OI) 44, OI-48, OI-50, OI-57, OI-71 and OI-122. Results showed that 100% of STEC strains investigated harbored genes associated with EHEC-related virulence profile patterns (eae and stx, with either espK, espV, ureD and/or Z2098). We also found similarities in virulence-related gene content between O157:H7 and O103:H2 dairy and non-dairy STEC strains, especially isolates from human cases. The O26:H11-serotype STEC strains investigated harbor the arcA-allele 2 gene associated with specific genetic markers. These profiles are associated with high-virulence seropathotype-A STEC. However, the low frequency of stx2 gene associated with absence of other virulence genes in dairy isolates of O26:H11 remains a promising avenue of investigation to estimate their real pathogenicity. All O26:H11 attaching-effacing E. coli (AEEC) strains carried CRISPRSP_O26_E but not genetic markers espK, espV, ureD and/or Z2098 associated with the emerging potentially high-virulence "new French clone". These strains are potentially as "EHEC-like" strains because they may acquire (or have lost) stx gene. In this study, O157:H7, O103:H2 and O26:H11 STEC strains isolated from dairy products were assigned as potential pathogens. However, research now needs to investigate the impact of dairy product environment and dairy processing on the expression of their pathogenicity.
产志贺毒素致病性大肠杆菌（STEC）在全球范围内被公认为是环境性和食源性病原菌，可通过摄入即食食品（如生乳衍生产品）进行传播。STEC在乳制品中的流行率为0.9%，但与乳制品消费相关的疫情爆发相对较少。在本研究中，我们使用逆转录定量聚合酶链反应（rt-qPCR），通过分析毒力相关基因频率以及与O岛（OI）44、OI-48、OI-50、OI-57、OI-71和OI-122的关联，来鉴定从生乳乳制品中分离出的O157、O26和O103 STEC菌株的毒力潜力。结果显示，所有被调查的STEC菌株都携带与肠出血性大肠杆菌（EHEC）相关毒力谱模式（eae和stx，以及espK、espV、ureD和/或Z2098）相关的基因。我们还发现O157:H7和O103:H2乳制品及非乳制品STEC菌株之间，尤其是来自人类病例的分离株，在毒力相关基因含量上存在相似性。被调查的O26:H11血清型STEC菌株携带与特定遗传标记相关的arcA等位基因2基因。这些图谱与高毒力血清致病型-A STEC相关。然而，O26:H11乳制品分离株中与其他毒力基因缺失相关的stx2基因频率较低，这仍是评估其实际致病性的一个有前景的研究途径。所有O26:H11黏附性抹平大肠杆菌（AEEC）菌株都携带CRISPRSP_O26_E，但不携带与新兴的潜在高毒力“新法国克隆”相关的遗传标记espK、espV、ureD和/或Z2098。这些菌株可能是“类EHEC”菌株，因为它们可能获得（或已经丢失）了stx基因。在本研究中，从乳制品中分离出的O157:H7、O103:H2和O26:H11 STEC菌株被认定为潜在病原体。然而，现在的研究需要调查乳制品环境和乳制品加工对其致病性表达的影响。
