Molecular characterization of O157:H7, O26:H11 and O103:H2 Shiga toxin-producing Escherichia coli isolated from dairy products.

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Abstract

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 CRISPRO26:H11SP_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.

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Author and article information

Journal

Journal ID (iso-abbrev): Int. J. Food Microbiol.

Title: International journal of food microbiology

Publisher: Elsevier BV

ISSN (Electronic): 1879-3460

ISSN (Print): 0168-1605

Publication date (Electronic): Jul 17 2017

Volume: 253

Affiliations

[1 ] 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. Electronic address: tdouellou@clermont.inra.fr.

[2 ] Université Paris-Est, ANSES, Laboratoire de Sécurité des Aliments, Plateforme IdentyPath, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort, France.

[3 ] 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 de Lyon, VetAgro Sup Campus Vétérinaire, Laboratoire d'Etudes des Microorganismes Alimentaires Pathogènes-French National Reference laboratory for Escherichia coli including Shiga toxin-producing E. coli (NRL-STEC), 69280 Marcy l'Etoile, France.

[4 ] Institute National de Recherche Agronomique, Unité de Recherches Fromagères, 15000 Aurillac, France.

Article

Publisher Item ID: S0168-1605(17)30169-1

DOI: 10.1016/j.ijfoodmicro.2017.04.010

PubMed ID: 28499121

SO-VID: da20af62-e42b-4443-8c7e-3c177643db74

History

Keywords: Dairy products,Non-O157 STEC,O157 STEC,Virulence genetic markers

Data availability:

Keywords: Dairy products, Non-O157 STEC, O157 STEC, Virulence genetic markers

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