title: Shiga toxin-producing Escherichia coli strains isolated from dairy products - Genetic diversity and virulence gene profiles.
abstract: Shiga toxin-producing Escherichia coli (STEC) are widely recognized as pathogens causing food borne disease. Here we evaluate the genetic diversity of 197 strains, mainly STEC, from serotypes O157:H7, O26:H11, O103:H2, O111:H8 and O145:28 and compared strains recovered in dairy products against strains from human, meat and environment cases. For this purpose, we characterized a set of reference-collection STEC isolates from dairy products by PFGE DNA fingerprinting and a subset of these by virulence-gene profiling. PFGE profiles of restricted STEC total DNA showed high genomic variability (0.9976 on Simpson's discriminatory index), enabling all dairy isolates to be differentiated. High-throughput real-time PCR screening of STEC virulence genes were applied on the O157:H7 and O26:H11 STEC isolates from dairy products and human cases. The virulence gene profiles of dairy and human STEC strains were similar. Nevertheless, frequency-wise, stx1 was more prevalent among dairy O26:H11 isolates than in human cases ones (87% vs. 44%) while stx2 was more prevalent among O26:H11 human isolates (23% vs. 81%). For O157:H7 isolates, stx1 (0% vs. 39%), nleF (40% vs 94%) and Z6065 (40% vs 100%) were more prevalent among human than dairy strains. Our data point to differences between human and dairy strains but these differences were not sufficient to associate PFGE and virulence gene profiles to a putative lower pathogenicity of dairy strains based on their lower incidence in disease. Further comparison of whole-genome expression and virulence gene profiles should be investigated in cheese and intestinal tract samples.
authors.affiliation: INRA UR Fromagères 545, 20 Cote de Reyne, 15000 Aurillac, France; Université de Lyon, "Bacterial Opportunistic Pathogens and Environment" Research Group, UMR5557 Ecologie Microbienne Lyon, Université Lyon 1, CNRS, VetAgro Sup, 69280 Marcy l'Etoile, France.
authors.forename: T
authors.initials: T
authors.lastname: Douëllou
authors.affiliation: Université Paris-Est, ANSES, Laboratoire de Sécurité des Aliments, Plateforme IdentyPath, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort, France.
authors.forename: S
authors.initials: S
authors.lastname: Delannoy
authors.affiliation: Université de Lyon, "Bacterial Opportunistic Pathogens and Environment" Research Group, UMR5557 Ecologie Microbienne Lyon, Université Lyon 1, CNRS, VetAgro Sup, 69280 Marcy l'Etoile, France; Université de Lyon, VetAgro Sup Campus Vétérinaire, Laboratoire d'études des Microorganismes Alimentaires Pathogènes, French National Reference Laboratory for Escherichia coli including Shiga-like toxin-producing E. coli (NRL-STEC), 69280 Marcy-l'Etoile, France.
authors.forename: S
authors.initials: S
authors.lastname: Ganet
authors.affiliation: Centre National de Référence Associé des Escherichia coli, AP-HP, Service de Microbiologie, Hôpital Robert-Debré, 75019 Paris, France.
authors.forename: P
authors.initials: P
authors.lastname: Mariani-Kurkdjian
authors.affiliation: Université Paris-Est, ANSES, Laboratoire de Sécurité des Aliments, Plateforme IdentyPath, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort, France.
authors.forename: P
authors.initials: P
authors.lastname: Fach
authors.affiliation: Université de Lyon, "Bacterial Opportunistic Pathogens and Environment" Research Group, UMR5557 Ecologie Microbienne Lyon, Université Lyon 1, CNRS, VetAgro Sup, 69280 Marcy l'Etoile, France; Université de Lyon, VetAgro Sup Campus Vétérinaire, Laboratoire d'études des Microorganismes Alimentaires Pathogènes, French National Reference Laboratory for Escherichia coli including Shiga-like toxin-producing E. coli (NRL-STEC), 69280 Marcy-l'Etoile, France.
authors.forename: E
authors.initials: E
authors.lastname: Loukiadis
authors.affiliation: INRA UR Fromagères 545, 20 Cote de Reyne, 15000 Aurillac, France.
authors.forename: Mc
authors.initials: M
authors.lastname: Montel
authors.affiliation: Université de Lyon, "Bacterial Opportunistic Pathogens and Environment" Research Group, UMR5557 Ecologie Microbienne Lyon, Université Lyon 1, CNRS, VetAgro Sup, 69280 Marcy l'Etoile, France; Université de Lyon, VetAgro Sup Campus Vétérinaire, Laboratoire d'études des Microorganismes Alimentaires Pathogènes, French National Reference Laboratory for Escherichia coli including Shiga-like toxin-producing E. coli (NRL-STEC), 69280 Marcy-l'Etoile, France. Electronic address: delphine.sergentet@vetagro-sup.fr.
authors.forename: D
authors.initials: D
authors.lastname: Thevenot-Sergentet
mesh_terms: D000818:Animals; D044822:Biodiversity; D002611:Cheese / Q000382:microbiology*; D016172:DNA Fingerprinting; D004927:Escherichia coli Infections / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000235:genetics* / Q000302:isolation & purification* / Q000472:pathogenicity; D005517:Foodborne Diseases / Q000382:microbiology*; D014644:Genetic Variation / Q000235:genetics; D006801:Humans; D008460:Meat / Q000382:microbiology*; D015995:Prevalence; D012703:Serotyping; D022622:Shiga Toxin 1 / Q000235:genetics; D022641:Shiga Toxin 2 / Q000235:genetics; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; D037521:Virulence Factors
keywords: Biodiversity; Dairy products; Genetic; STEC