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Effects of E. coli O157:H7 Vaccination on the Prevalence and Load of E. coli O157:H7 and Non-O157 STEC on the Hides of Beef Cattle at Harvest

Wheeler, Tommy Lee; Kalchayanand, Norasak; Bosilevac, Joseph; Arthur, Terrance
USDA - Agricultural Research Service
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Escherichia coli O157:H7 remains the major foodborne pathogen of concern for the beef industry. Extensive research has been conducted and is on-going to identify and develop novel intervention strategies to reduce E. coli O157:H7 from live cattle and processed carcasses. Recent work has shown that hides are the main source of beef carcass contamination at slaughter and as such reductions in the prevalence of E. coli O157:H7 on the hide are directly related to lower carcass prevalence rates. Interventions applied to cattle during production have been designed to reduce hide contamination indirectly through lowering the prevalence and levels of E. coli O157:H7 shed in the feces of cattle.

Emerging technologies to reduce the prevalence of E. coli O157:H7 from cattle before arrival at a harvest facility have proven promising in small scale feedlot studies. The present study evaluated the efficacy of the Epitopix SRP E. coli O157:H7 vaccine under large scale commercial conditions. The vaccinated cattle were compared to cattle slaughter during the same timeframe from feedlots in the same general region. While E. coli O157:H7 was the main target of the vaccine and the main focus of this work, we also analyzed a subset of samples for vaccine effects on non-O157 Shiga toxinproducing E. coli (STEC). Also, isolates were analyzed for tracking purposes to determine the contribution to hide contamination made by the lairage environment (defined as processing plant holding pen area).

The stated objectives for this work were to:
1. Evaluate vaccination on hide prevalence and levels of E. coli O157:H7 and non-O157 STEC from vaccinates vs. non-vaccinates.
2. Determine relatedness of E. coli O157:H7 isolates obtained from hide and fecal samples.

More information
Over 4,000 total hide samples were collected from both vaccinated and non-vaccinated animals to determine the vaccine�s effect. E. coli O157:H7 was not found to be less prevalent on cattle hides of vaccinated animals. Further analysis indicated that the results obtained in this study may not have been an accurate measure of the vaccine�s effects on cattle hides due to the acquisition of additional hide contamination at the processing plant animal holding area. This additional contamination likely masked any effect of the vaccine, making conclusions based on this data set less reliable.
Funding Source
Nat'l. Cattlemen's Beef Assoc.
Project number
Escherichia coli
Bacterial Pathogens