Kansas State University researchers are conducting a series of studies to test a vaccine, which may reduce the presence of E. coli O157 in feedlot cattle, says T.G. Nagaraja, professor of microbiology in the College of Veterinary Medicine.
E. coli O157, a pathogen commonly found in the feces of beef cattle, can enter the food chain during harvest and not only cause foodborne illnesses in humans, but can also have economic implications for producers, says Nagaraja.
The researchers, who are part of K-State Research and Extension, recently completed the third study in a series of experiments, which included 60 feedlot calves that all tested positive for E. coli O157, says Daniel Thomson, who is the Jones professor of production medicine and epidemiology for the K-State College of Veterinary Medicine.
The calves were divided into one of three treatment groups that each received different doses of the vaccine (Escherichia coli O157 Siderophore Receptor Porin) on days zero and 21 of the eight-week experiment. Group one, which was the control group, received a placebo vaccine; group two was administered two cubic centimeters (cc) of the vaccine; and group three was given three cc.
The study showed that the total prevalence of E. coli O157 in cattle that received three cc of the vaccine decreased by 15% when compared to cattle that received a placebo, says Nagaraja. The overall prevalence for each treatment group was: 33.7% for the placebo group; 29.1% for group two which received two cc of the vaccine; and 17.7% for group three which received three cc – the highest dose administered.
This study was the third in a series of studies in which the first two also showed promising results, Thomson says. The first study was conducted as a challenge study where the cattle were first administered the vaccine and then challenged, or orally introduced, to the E. coli O157 bacteria.
"In the first study we saw a significant decrease in animals with E. coli and it appeared to be a very promising vaccine to take into the field to study," Thomson says. "The second study was conducted on 20 lots of cattle in a commercial feedlot in Nebraska."
The results of the second study showed a 60% reduction in the number of cattle shedding E. coli O157 relative to the cattle that were given a placebo vaccine, he says.
K-State will conduct another study this summer in a feedlot setting and may look at the effects of different doses, says Thomson.