Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed June 11, 2007). PDF text: x, 168 p. : ill. ; 21.64 Mb. UMI publication number: AAT 3243741. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph.D.) - University of Queensland, 2002. / Includes bibliography.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

published_or_final_version / abstract / Microbiology / Master / Master of Philosophy

Diversity analysis of Escherichia coli have routinely utilised isolates obtained by culture of faeces on MacConkey selective media, under the assumption that the diversity identified in faecal isolates are representative of similar diversity in E. coli in the gastrointestinal tract (GIT). This study has addressed this important issue by specifically isolating E. coli from different regions of the gut in pigs and subjecting them to enzymatic multilocus enzyme electrophoresis (MLEE) and molecular virulence factor (VF) analysis to ascertain whether E. coli populations inhabiting different regions of the gut are different from each other. Combination of these results showed that on average, E. coli strains isolated from the upper GIT region (small intestine) of the pig are distinctly different from the E. coli strains isolated from the lower GIT region (large intestine). An important aspect of the finding that faecal E. coli are not truly representative of the diversity in the GIT is the mechanism used by specific clonotypes that have adapted to different geographical habitats to survive challenge from incoming strains. / Doctor of Philosophy (PhD)

Transfer 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. / xii, 102 leaves : ill. ; 28 cm.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1994. / Includes bibliographical references (leaves 147-160). / Microfiche. / xvii, 160 leaves, bound ill. 29 cm

Thesis (M. Phil.)--University of Hong Kong, 2007. / Also available in print.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2007. / Härtill 5 uppsatser.

Thesis (Ph. D., Microbiology, Molecular Biology and Biochemistry)--University of Idaho, November 2006. / Major professor: Carloyn H. Bohach. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.