title: Pathogenicity of Escherichia coli O157:H7 in the intestines of neonatal calves.
abstract: Cattle are an important reservoir of Shiga toxin-producing enterohemorrhagic Escherichia coli (EHEC) O157:H7 strains, foodborne pathogens that cause hemorrhagic colitis and hemolytic uremic syndrome in humans. EHEC O157:H7 strains are not pathogenic in calves >3 weeks old. Our objective was to determine if EHEC O157:H7 strains are pathogenic in neonatal calves. Calves <36 h old inoculated with EHEC O157:H7 developed diarrhea and enterocolitis with attaching and effacing (A/E) lesions in both the large and small intestines by 18 h postinoculation. The severity of diarrhea and inflammation, and also the frequency and extent of A/E lesions, increased by 3 days postinoculation. We conclude that EHEC O157:H7 strains are pathogenic in neonatal calves. The neonatal calf model is relevant for studying the pathogenesis of EHEC O157:H7 infections in cattle. It should also be useful for identifying ways to reduce EHEC O157:H7 infections in cattle and thus reduce the risk of EHEC O157:H7 disease in humans.
authors.affiliation: Enteric Diseases and Food Safety Research Unit, National Animal Disease Center, USDA Agricultural Research Service, Ames, Iowa 50010, USA. enystrom@nadc.ars.usda.gov
authors.forename: E A
authors.initials: EA
authors.lastname: Dean-Nystrom
authors.forename: B T
authors.initials: BT
authors.lastname: Bosworth
authors.forename: W C
authors.initials: WC
authors.lastname: Cray
authors.forename: H W
authors.initials: HW
authors.lastname: Moon
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D002417:Cattle; D003967:Diarrhea / Q000382:microbiology; D004760:Enterocolitis / Q000382:microbiology; D004927:Escherichia coli Infections / Q000276:immunology / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000472:pathogenicity*; D005856:Germ-Free Life; D007082:Ileum / Q000382:microbiology / Q000473:pathology / Q000648:ultrastructure; D007150:Immunohistochemistry; D007249:Inflammation / Q000382:microbiology; D007420:Intestine, Large / Q000382:microbiology / Q000473:pathology; D007421:Intestine, Small / Q000382:microbiology / Q000473:pathology; D008297:Male; D008854:Microscopy, Electron; D013552:Swine