Transfer of rifampicin-resistant Escherichia coli among feedlot cattle

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dc.contributor.authorStevenson, Sam M. L.
dc.contributor.authorUniversity of Lethbridge. Faculty of Arts and Science
dc.contributor.supervisorSelinger, L. Brent
dc.contributor.supervisorMcAllister, Tim A.
dc.date.accessioned2007-05-13T20:29:44Z
dc.date.available2007-05-13T20:29:44Z
dc.date.issued2002
dc.degree.levelMasters
dc.descriptionxii, 102 leaves : ill. ; 28 cm.en
dc.description.abstractTransfer and shedding of a rifampicin-resistant strain of Escherichia coli (RREC) among cattle was studied in a research feedlot comprised of 30 pens of 11 or 12 yearling steers. On 3 separate occasions, 9,6 and 6 of the 12 steers in 3 different peripheral pens in the lot were orally inoculated with 1011 cells of an unmodified RREC isolate from bovine feces. Fecal swabs were preformed on all 360 steers in the feedlot immediately prior to and at approximately 5-week intervals thereafter. Following inoculation, fecal grab samples were collected daily from all 12 pen mates for up to 4 months. In all 3 trials, the inoculated steers each shed RREC within 24 h of inoculation. All 12 steers in each inoculated pen were positive for RREC within 48 h; all 36 steers shed RREC intermittently throughout the three sampling periods. Transfer to 4 steers in an adjacent pen was confirmed only during the first trial (3 steers shed once each on day 8, day 26 or day 40; the fourth shed on 6 occasions between days 8 and 40). Transfer to non-adjacent pens was not detected during any of the 3 trials. All recovered RREC isolates were compared to the inocula using LMX agar and fatty acid methyl ester (FAME) analysis. Additionally, select recovered isolates were subjected to carbon source utilization tests. The three inocula were further subjected to 16S rRNA sequence analysis, minimum inhibitory antibiotic concentration profiles and pulsed-field gel electrophoresis and were determined to be the same strain. It was observed with the exception of the pen floor, that the resistant strain did not move through the animal feedlot environment, as easily or pervasively as other studies suggested. The RREC did not persist in the feedlot environment beyond the 4-month trial period. Fecal contamination form the pen floor, animal-to-animal contact and the chute system may have facilitated transfer of the resistant strain between animals. Animal stress may have facilitated the pen-to-pen transfer observed during trial 1, as the inoculation was conducted within 1 week of the steers' arrival in the feedlot.en
dc.identifier.urihttps://hdl.handle.net/10133/237
dc.language.isoen_USen
dc.publisherLethbridge : University of Lethbridge, Facutly of Arts and Science, 2002en
dc.publisher.departmentDepartment of Biological Sciences
dc.publisher.facultyArts and Science
dc.relation.ispartofseriesThesis (University of Lethbridge. Faculty of Arts and Science)en
dc.subjectEscherichia coli infections in animalsen
dc.subjectCattle -- Infectionsen
dc.subjectFeedlotsen
dc.subjectDissertations, Academicen
dc.titleTransfer of rifampicin-resistant Escherichia coli among feedlot cattleen
dc.typeThesisen
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