title: Interaction with avian cells and colonisation of specific pathogen free chicks by Shiga-toxin negative Escherichia coli O157:H7 (NCTC 12900).
abstract: The prevalence of Escherichia coli O157:H7 infection in birds is low but several deliberate inoculation studies show that poultry are readily and persistently infected by this organism indicating a possible threat to public health. The mechanisms of colonisation of poultry are not understood and the aim is to establish models to study the interaction of E. coli O157:H7, at the cellular and whole animal levels. A non-toxigenic E. coli O157:H7 (NCTC 12900) was used in adherence assays with an avian epithelial cell line (Div-1) and used to inoculate 1-day-old SPF chicks. In vitro, NCTC 12900 induced micro-colonies associated with cytoskeletal arrangements and pedestal formation with intimate bacterial attachment. In the 1-day-old SPF chick, a dose of 1 x 10(5) cfu resulted in rapid and extensive colonisation of the gastrointestinal tract and transient colonisation of the liver and spleen. The number of E. coli O157:H7 organisms attained approximately 10(8) cfu/ml caecal homogenate 24h after inoculation and approximately 10(7) cfu/ml caecal homogenate was still present at day 92. Faecal shedding persisted for 169 days, ceasing 9 days after the birds came into lay and 6% of eggs were contaminated on the eggshell. Histological analysis of tissue samples from birds dosed with 1x10(7) cfu gave evidence for E. coli O157:H7 NCTC 12900 induced micro-colonies on the caecal mucosa, although evidence for attaching effacing lesions was equivocal. These models may be suitable to study those factors of E. coli O157:H7 that mediate persistent colonisation in avian species.
authors.affiliation: Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7BX, UK.
authors.forename: Angus
authors.initials: A
authors.lastname: Best
authors.forename: Roberto M
authors.initials: RM
authors.lastname: La Ragione
authors.forename: William A
authors.initials: WA
authors.lastname: Cooley
authors.forename: C David
authors.initials: CD
authors.lastname: O'Connor
authors.forename: Phillipe
authors.initials: P
authors.lastname: Velge
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Woodward
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology; D002645:Chickens; D002988:Cloaca / Q000382:microbiology; D015169:Colony Count, Microbial / Q000662:veterinary; D004528:Egg Shell / Q000382:microbiology; D004847:Epithelial Cells / Q000382:microbiology; D004927:Escherichia coli Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D005260:Female; D005516:Food Microbiology; D007422:Intestines / Q000382:microbiology; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D011201:Poultry Diseases / Q000382:microbiology* / Q000473:pathology; D013047:Specific Pathogen-Free Organisms