title: E. coli O157 from sheep in northeast Scotland: prevalence, concentration shed, and molecular characterization by multilocus variable tandem repeat analysis.
abstract: We report the prevalence, concentrations, and strain diversity of Escherichia coli O157 shed by sheep fed on root crops during a winter period in northeast Scotland. E. coli O157 was isolated on 6 farms from 14 studied during January to March 2005. The individual sheep prevalence was 5.8% and concentration excreted was <10(2) colony-forming units/g for all but one fecal sample. Verocytotoxigenic E. coli O157, determined by polymerase chain reaction and verocell assay, was recovered from 27% of samples. Four farms had sheep shedding the same strain as determined by multiple-locus variable analysis and no within-farm diversity was observed. The low numbers shed and the high levels of atoxigenic strains indicate a lower risk to human health from these animals compared to many ruminants grazing pasture during summer months. These data will be valuable for quantitative risk assessments and provide preliminary information that feeding sheep on root crops may be a practical intervention to reduce E. coli O157 infection in animals and ultimately humans.
authors.affiliation: Applied Food Microbiology Group, School of Medicine, University of Aberdeen, Aberdeen, UK.
authors.forename: Olivia
authors.initials: O
authors.lastname: Solecki
authors.forename: Marion
authors.initials: M
authors.lastname: MacRae
authors.forename: Norval
authors.initials: N
authors.lastname: Strachan
authors.forename: Bjørn-Arne
authors.initials: BA
authors.lastname: Lindstedt
authors.forename: Iain
authors.initials: I
authors.lastname: Ogden
mesh_terms: D000483:Alleles; D000818:Animals; D057138:Bacterial Shedding; D001937:Brassica; D002470:Cell Survival; D002522:Chlorocebus aethiops; D015169:Colony Count, Microbial; D016001:Confidence Intervals; D004032:Diet; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000235:genetics* / Q000302:isolation & purification* / Q000472:pathogenicity; D005243:Feces / Q000382:microbiology; D014644:Genetic Variation; D006801:Humans; D018598:Minisatellite Repeats; D009010:Monte Carlo Method; D018517:Plant Roots; D015995:Prevalence; D012606:Scotland / Q000453:epidemiology; D012621:Seasons; D012756:Sheep / Q000382:microbiology*; D012757:Sheep Diseases / Q000453:epidemiology* / Q000382:microbiology; D014709:Vero Cells; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D037521:Virulence Factors