|Chase, Chadwick - Chad|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2003
Publication Date: 3/23/2003
Citation: Riley, D.G., Gray, J.T., Loneragan, G.H., Barling, K.S., Chase, C.C. Escherichia coli o157::h7 prevalence in fecal samples of cattle from a southeastern beef cow-calf herd. Journal of Food Protection Vol. 66, pp.1778-1782. Interpretive Summary: Escherichia coli O157:H7 continues to result in many cases of human illness in the United States in each year. Contaminated beef is a highly publicized source of the pathogen. The entire beef production process is being examined for points where E. coli O157:H7 levels could be controlled or reduced. Limited investigations of E. coli O157:H7 levels in the cow-calf segment of beef production have been conducted in the northern and western parts of the United States. Because one third to one half of the nation's beef originates in the states along the Gulf Coast, the aim of this study was to measure the occurrence of E. coli O157:H7 in manure samples of cows in Florida. Manure samples were obtained from 296 cows for three months in the fall of 2001. E. coli O157:H7 was detected in 3.0% of all samples, and 9.1% of cows had the pathogen detected in at least one sample. Results indicated that cows that had weaned a calf were more likely to have a manure sample with detected E. coli O157:H7. Angus and Brahman cows had higher levels of E. coli O157:H7 in manure samples than Romosinuano cows. Results also indicated that southern cow-calf operations have E. coli O157:H7 levels in manure samples that are as high as those in northern operations. Further investigations should be conducted to verify the effect of lactation (weaning a calf) and the effect of cow breedtype on pathogen levels.
Technical Abstract: The proportion of fecal samples culture-positive for Escherichia coli O157:H7 was determined for samples collected from 296 beef cows on pasture in a single Florida herd in October, November, and December of 2001. The overall proportion of samples cultured positive was 0.03. Of the cows from which samples were collected, 9.1% were culture-positive on at least one occasion. No effect of pregnancy status or nutritional regimen on the proportion of culture-positive samples for E. coli O157:H7 was detected. We detected a breed effect on the shedding of E. coli O157 with Romosinuano cows having a lower (P < 0.01) proportion of samples culture-positive than Angus or Brahman cows. This difference may have resulted from the presence of confounding variables, however, it also may represent evidence of breed-to-breed genetic variation in E. coli O157 shedding. Further research is warranted to evaluate breed as a possible risk factor for shedding of this important food-borne pathogen. Further substantiated findings may indicate that breed is a cow-calf-level critical control point of E. coli O157:H7.