Classical and molecular epidemiology of campylobacter, in particular Campylobacter jejuni, in the Alberta beef industry
Hannon, Sherry J
This research used classical and molecular epidemiology tools to assess the potential importance of feedlot cattle as Campylobacter reservoirs. The project was conducted from November 2004 to September 2005 in southern Alberta. Fresh pen-floor fecal samples were collected from commercial feedlot cattle near slaughter weight in seven feedlots. Overall, 87% of 2,776 fecal samples were culture positive for Campylobacter species (86% of 1,400 in winter, 88% of 1,376 in summer), and 69% of 1,486 Campylobacter positive isolates were identified as Campylobacter jejuni. After accounting for clustering within pen and feedlot, the number of days-on-feed and feedlot size were associated (p ¡Ü 0.05) with Campylobacter species isolation rates. Retail ground beef was collected from 60 grocery stores (four chains, three cities). None of the 1,200 packages were culture positive for Campylobacter species. Polymerase chain reaction (PCR) results from a subset of samples (n=142) indicated that 48% of packages were positive for Campylobacter DNA. By species, 14.8% (21/142), 26.8% (38/142) and 1.4% (2/142) of packages were PCR positive for C. jejuni, C. coli and C. hyointestinalis DNA, respectively. The collection period (1, 2, 3 or 4) was associated (p ¡Ü 0.05) with the odds of detecting Campylobacter species DNA using PCR. Oligonucleotide DNA microarrays were used as a platform for comparative genomic hybridization (CGH) analysis of 87 C. jejuni isolates (46 bovine, 41 human) obtained within the same geographical regions and time frame. Of the 13 CGH clusters identified based on overall comparative genomic profile similarity, nine contained human and cattle isolates, three contained only human isolates, and one contained only cattle isolates. In addition, human clinical and feedlot cattle C. jejuni isolates were compared on a gene-by-gene basis and only a small number of the 1,399 genes tested were unequally distributed between the two groups (p ¡Ü 0.05). The high isolation rates of Campylobacter species and C. jejuni reported here may have implications for food safety, public health and environmental contamination. Our findings suggest that feedlot cattle and human C. jejunistrains are very similar and may be endemic within southern Alberta.
DegreeDoctor of Philosophy (Ph.D.)
DepartmentLarge Animal Clinical Sciences
ProgramLarge Animal Clinical Sciences
CommitteeWaldner, Cheryl; Russell, Margaret; Potter, Andrew A.; Carruthers, Terry D.; Allan, Brenda; Weese, J. Scott
retail ground beef