title: Characterization of Shiga Toxin-Producing Escherichia coli O157 Isolates from Bovine Carcasses.
abstract: The main purpose of this study was to determine the prevalence of Escherichia coli O157 on bovine carcasses before and after chilling at a large slaughterhouse located in the city of Barcelona, Spain, to assess the effectiveness of dry chilling on reducing E. coli O157 contamination of carcasses. In addition, the study characterized the E. coli O157 strains isolated in terms of virulence factors, antibiotic susceptibility, and their genetic diversity. Individual bovine carcasses were sampled before (n = 300) and after (n = 300) chilling over an 8-month period. Positive samples for E. coli O157 were subjected to virulence screening by PCR (stx1, stx2, and eaeA genes and the fliCH7 gene), antimicrobial susceptibility testing, and molecular typing by pulsed-field gel electrophoresis. A total of 9.7% (29 of 300) of the nonrefrigerated carcasses examined and 2.3% (7 of 300) of the refrigerated carcasses were positive for E. coli O157. All the isolates were serotype O157:H7, 92% (33 of 36) carried the stx1, stx2, and eaeA genes, and 8% (3 of 36) carried the stx2 and eaeA genes. Antimicrobial susceptibility testing showed a high degree of resistance: 29 strains (81%) were resistant to at least 1 antimicrobial of the 12 antimicrobials tested; 69% (25 of 36) were resistant to 4 or more antimicrobials. Molecular typing by pulsed-field gel electrophoresis found a high diversity of genetic types, implying little cross-contamination in the slaughterhouse. This study confirms that E. coli O157:H7 is present on the carcasses slaughtered in Spain, although its prevalence is reduced by the dry chilling process used. The recovered isolates showed potential pathogenesis and a high degree of multidrug resistance, confirming the importance of bovine meat monitoring.
authors: Agèencia de Salut Pública de Barcelona (Public Health Agency of Barcelona), Pl Lesseps 1, 08023 Barcelona, Spain; The Biomedical Research Center Network for Epidemiology and Public Health (CIBERESP), Melchor Fernández Almagro 3-5, 28029 Madrid, Spain; Institut d'Investigació Biomèedica Sant Pau, Sant Antoni Maria Claret, 167, 08025 Barcelona, Spain. mfontcub@aspb.cat.
authors: M
authors: M
authors: Fontcuberta
authors: Agèencia de Salut Pública de Barcelona (Public Health Agency of Barcelona), Pl Lesseps 1, 08023 Barcelona, Spain.
authors: R
authors: R
authors: Planell
authors: Agèencia de Salut Pública de Barcelona (Public Health Agency of Barcelona), Pl Lesseps 1, 08023 Barcelona, Spain.
authors: A
authors: A
authors: Torrents
authors: Agèencia de Salut Pública de Barcelona (Public Health Agency of Barcelona), Pl Lesseps 1, 08023 Barcelona, Spain.
authors: S
authors: S
authors: Sabaté
authors: Agèencia de Salut Pública de Barcelona (Public Health Agency of Barcelona), Pl Lesseps 1, 08023 Barcelona, Spain.
authors: R
authors: R
authors: Gonzalez
authors: Agèencia de Salut Pública de Barcelona (Public Health Agency of Barcelona), Pl Lesseps 1, 08023 Barcelona, Spain.
authors: M
authors: M
authors: Ramoneda
authors: Agèencia de Salut Pública de Barcelona (Public Health Agency of Barcelona), Pl Lesseps 1, 08023 Barcelona, Spain.
authors: M
authors: M
authors: de Simón
mesh_terms: D000003:Abattoirs; D000818:Animals; D002417:Cattle; D004926:Escherichia coli / Q000302:isolation & purification*; D019453:Escherichia coli O157 / Q000302:isolation & purification; D005516:Food Microbiology; D008460:Meat; D016133:Polymerase Chain Reaction; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics*; D013030:Spain