title: Shedding of Escherichia coli O157:H7 in dairy cattle housed in a confined environment following waterborne inoculation.
abstract: A study of Escherichia coli O157:H7 transmission and shedding was conducted with bull calves housed in individual pens within a confined environment. For comparative purposes, the numbers and duration of E. coli O157:H7 shedding in naturally infected calves were monitored after a single purchased calf (calf 156) tested positive prior to inoculation. During the next 8 days, the calves in adjacent pens and a pen directly across a walkway from calf 156 began to shed this serotype O157:H7 strain. Five of the eight calves in this room shed this O157:H7 strain at some time during the following 8 weeks. The numbers of E. coli O157:H7 isolates shed in these calves varied from 60 to 10(5) CFU/g of feces, and the duration of shedding ranged from 17 to >31 days. The genomic DNAs from isolates recovered from these calves were indistinguishable when compared by using XbaI digestion and pulsed-field gel electrophoresis. Inoculation of calves with 1 liter of water containing ca. 10(3) to 10(4) CFU of E. coli O157:H7/ml resulted in shedding in 10 of 12 calves (trial 1, 4 of 4 calves; trial 2, 6 of 8 calves). The inoculated calves shed the inoculation strain (FRIK 1275) as early as 24 h after administration. The duration of shedding varied from 18 to >43 days at levels from 10(2) to 10(6) CFU/g of feces. The numbers of doses necessary to initiate shedding varied among calves, and two calves in trial 2 never shed FRIK 1275 after four doses (ca. 10(6) CFU per dose). Results from this study confirm previous reports of animal-to-animal and waterborne dissemination of E. coli O157:H7 and highlight the need for an effective water treatment to reduce the spread of this pathogen in cattle.
authors.affiliation: United States Department of Agriculture, Animal, Plant Health Inspection Service, Veterinary Services, Madison, Wisconsin 53719, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Shere
authors.forename: C W
authors.initials: CW
authors.lastname: Kaspar
authors.forename: K J
authors.initials: KJ
authors.lastname: Bartlett
authors.forename: S E
authors.initials: SE
authors.lastname: Linden
authors.forename: B
authors.initials: B
authors.lastname: Norell
authors.forename: S
authors.initials: S
authors.lastname: Francey
authors.forename: D M
authors.initials: DM
authors.lastname: Schaefer
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology / Q000635:transmission*; D015169:Colony Count, Microbial; D003612:Dairying; D004927:Escherichia coli Infections / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology*; D005618:Fresh Water / Q000382:microbiology; D006799:Housing, Animal