title: Short communication: Behavior of different Shiga toxin-producing Escherichia coli serotypes (O26:H11, O103:H2, O145:H28, O157:H7) during the manufacture, ripening, and storage of a white mold cheese.
abstract: Ruminants are healthy carriers of Shiga toxin-producing Escherichia coli (STEC). If good hygienic and agricultural practices at the farm level, especially during the milking process, are not adequately followed, milk and dairy products made with raw milk could become contaminated. Sporadic cases and rare food outbreaks have been linked with dairy products. Consequently, understanding STEC behavior in cheeses would help to evaluate risks for human health. The behavior of 4 different STEC strains belonging to the serotypes O26:H11, O103:H2, O145:H28, and O157:H7 were monitored during the manufacture, ripening, and storage of a white mold soft cheese. These strains, originating from dairy products, were inoculated individually in raw milk from cow at 10(2) cfu/mL. During the first 24 to 36h of the manufacturing stage, the STEC level increased by 2 to 3 log10 cfu/g. Over the course of the ripening stage, the concentration of the non-O157 STEC remained relatively constant, whereas a decrease of the E. coli O157:H7 concentration was observed. During the storage stage, the level of the different non-O157 STEC strains decreased slowly in the core and in the rind of cheeses. The non-O157 STEC level reached between 3.1 and 4.1 log10 cfu/g at d 56. Interestingly, the concentration of the E. coli O157:H7 strain decreased dramatically: the strains remained detectable only after enrichment. During ripening and storage, STEC levels were generally higher in rinds than in cheese cores. In contrast to what was seen in cheese cores, the E. coli O157:H7 strain remained enumerable in rinds during these steps. These results highlight that STEC can grow during the manufacture and survive during the ripening and storage of a white mold soft cheese.
authors.affiliation: Research Group on Bacterial Opportunistic Pathogens and Environment, Université de Lyon, VetAgro Sup, Campus Vétérinaire de Lyon, UMR 5557 Ecologie Microbienne CNRS, 69622 Villeurbanne, France.
authors.forename: S D
authors.initials: SD
authors.lastname: Miszczycha
authors.affiliation: Actalia, 74800 La Roche-sur-Foron, France.
authors.forename: N
authors.initials: N
authors.lastname: Bel
authors.affiliation: Actalia, 74800 La Roche-sur-Foron, France.
authors.forename: P
authors.initials: P
authors.lastname: Gay-Perret
authors.affiliation: Actalia, 74800 La Roche-sur-Foron, France.
authors.forename: V
authors.initials: V
authors.lastname: Michel
authors.affiliation: INRA, UR 545, Recherches Fromagères, 15000 Aurillac, France.
authors.forename: M C
authors.initials: MC
authors.lastname: Montel
authors.affiliation: Research Group on Bacterial Opportunistic Pathogens and Environment, Université de Lyon, VetAgro Sup, Campus Vétérinaire de Lyon, UMR 5557 Ecologie Microbienne CNRS, 69622 Villeurbanne, France; Laboratoire d'Étude des Microorganismes Alimentaires Pathogenes, French National Reference Laboratory for Escherichia coli including Shiga Toxin-Producing E. coli, Université de Lyon, VetAgro Sup, Campus Vétérinaire de Lyon, 69280 Marcy l'Etoile, France. Electronic address: delphine.sergentet@vetagro-sup.fr.
authors.forename: D
authors.initials: D
authors.lastname: Sergentet-Thevenot
mesh_terms: D000818:Animals; D002417:Cattle; D002611:Cheese; D004926:Escherichia coli; D019453:Escherichia coli O157; D029968:Escherichia coli Proteins / Q000235:genetics; D005260:Female; D005516:Food Microbiology; D005658:Fungi; D006801:Humans; D065288:Serogroup; D054323:Shiga-Toxigenic Escherichia coli
chemical_list: D029968:Escherichia coli Proteins
keywords: Shiga toxin-producing Escherichia coli; behavior; challenge tests; white mold soft cheese