title: Occurrence of non-sorbitol fermenting, verocytotoxin-lacking Escherichia coli O157 on cattle farms.
abstract: Escherichia coli O157 is often associated with hemorrhagic colitis and the hemolytic uremic syndrome (HUS). The verocytotoxins are considered to be the major virulence determinants. However, vt-negative E. coli O157 were recently isolated from patients with HUS. Several transmission routes to humans are described, but cattle feces are the primary source from which both the food supply and the environment become contaminated with E. coli O157. In a prevalence study performed on dairy, beef, mixed dairy/beef and veal farms in the summer of 2007, vt-negative isolates were detected on 11.8% (8/68) of the positive farms. From these eight farms, a total of 43 sorbitol-negative E. coli O157:H7 were collected. On five farms, only strains negative for the vt genes were present whereas both vt-negative and vt-positive strains could be detected on three other farms. Further characterization revealed that all isolates carried the eaeA and hlyA genes. Pulsed-field gel electrophoresis (PFGE) of all isolates resulted in nine different PFGE types and within the vt-negative strains, four different genotypes were identified, indicating that certain genetic clones are widespread over the cattle population.
authors.affiliation: Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Katrijn
authors.initials: K
authors.lastname: Cobbaut
authors.forename: Kurt
authors.initials: K
authors.lastname: Houf
authors.forename: Glenn
authors.initials: G
authors.lastname: Buvens
authors.forename: Ihab
authors.initials: I
authors.lastname: Habib
authors.forename: Lieven
authors.initials: L
authors.lastname: De Zutter
mesh_terms: D000818:Animals; D002417:Cattle / Q000382:microbiology*; D003603:Cytotoxins / Q000235:genetics / Q000302:isolation & purification; D003612:Dairying; D004534:Egypt; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D019453:Escherichia coli O157 / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism / Q000472:pathogenicity; D005838:Genotype; D006799:Housing, Animal / Q000592:standards; D008460:Meat / Q000382:microbiology; D022603:Shiga Toxins / Q000235:genetics / Q000302:isolation & purification; D013012:Sorbitol / Q000378:metabolism; D014774:Virulence
chemical_list: D003603:Cytotoxins; D022603:Shiga Toxins; D013012:Sorbitol