Bonanno Ludivine, Loukiadis Estelle, Mariani-Kurkdjian Patricia, Oswald Eric, Garnier Lucille, Michel Valérie, Auvray Frédéric
Université Paris-Est, Anses, Laboratory for Food Safety, Department of Microbiology, Maisons-Alfort, France ACTALIA Produits Laitiers, Laboratoire de Microbiologie d'Intérêt Laitier, La Roche sur Foron, France.
Université de Lyon, VetAgro Sup, Laboratoire d'Études des Microorganismes Alimentaires Pathogènes/Laboratoire National de Référence pour les Escherichia coli y Compris les E. coli Producteurs de Shiga-Toxines, Marcy l'Etoile, France Université de Lyon, UMR 5557 Ecologie Microbienne, Université Lyon 1, CNRS, VetAgro Sup, Equipe Bactéries Pathogènes et Opportunistes, Villeurbanne, France.
Appl Environ Microbiol. 2015 Jun;81(11):3712-21. doi: 10.1128/AEM.00077-15. Epub 2015 Mar 27.
Shiga toxin-producing Escherichia coli (STEC) is a food-borne pathogen that may be responsible for severe human infections. Only a limited number of serotypes, including O26:H11, are involved in the majority of serious cases and outbreaks. The main virulence factors, Shiga toxins (Stx), are encoded by bacteriophages. Seventy-four STEC O26:H11 strains of various origins (including human, dairy, and cattle) were characterized for their stx subtypes and Stx phage chromosomal insertion sites. The majority of food and cattle strains possessed the stx(1a) subtype, while human strains carried mainly stx(1a) or stx(2a). The wrbA and yehV genes were the main Stx phage insertion sites in STEC O26:H11, followed distantly by yecE and sbcB. Interestingly, the occurrence of Stx phages inserted in the yecE gene was low in dairy strains. In most of the 29 stx-negative E. coli O26:H11 strains also studied here, these bacterial insertion sites were vacant. Multilocus sequence typing of 20 stx-positive or stx-negative E. coli O26:H11 strains showed that they were distributed into two phylogenetic groups defined by sequence type 21 (ST21) and ST29. Finally, an EspK-carrying phage was found inserted in the ssrA gene in the majority of the STEC O26:H11 strains but in only a minority of the stx-negative E. coli O26:H11 strains. The differences in the stx subtypes and Stx phage insertion sites observed in STEC O26:H11 according to their origin might reflect that strains circulating in cattle and foods are clonally distinct from those isolated from human patients.
产志贺毒素大肠杆菌（STEC）是一种食源性病原体，可能导致严重的人类感染。只有少数血清型，包括O26:H11，涉及大多数严重病例和疫情爆发。主要毒力因子志贺毒素（Stx）由噬菌体编码。对74株不同来源（包括人类、乳制品和牛）的STEC O26:H11菌株进行了stx亚型和Stx噬菌体染色体插入位点的鉴定。大多数食品和牛源菌株具有stx(1a)亚型，而人类菌株主要携带stx(1a)或stx(2a)。wrbA和yehV基因是STEC O26:H11中主要的Stx噬菌体插入位点，其次是距离较远的yecE和sbcB。有趣的是，插入yecE基因的Stx噬菌体在乳制品菌株中的发生率较低。在本文研究的29株stx阴性大肠杆菌O26:H11菌株中，大多数菌株的这些细菌插入位点为空。对20株stx阳性或stx阴性大肠杆菌O26:H11菌株进行多位点序列分型，结果表明它们分为由序列类型21（ST21）和ST29定义的两个系统发育组。最后，发现大多数STEC O26:H11菌株的ssrA基因中插入了携带EspK的噬菌体，而stx阴性大肠杆菌O26:H11菌株中只有少数有这种情况。根据来源观察到的STEC O26:H11中stx亚型和Stx噬菌体插入位点的差异可能反映出，在牛和食品中传播的菌株在克隆上与从人类患者分离出的菌株不同。
