INTERVENTIONS TO REDUCE EPIZOOTIC PATHOGENIC BACTERIA IN SWINE AND CATTLE
Location: Food and Feed Safety Research
Title: Bacteriophage Isolated from Feedlot Cattle Can Reduce Escherichia coli O157:H7 Populations in Ruminant Gastrointestinal Tracts
Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 8, 2008
Publication Date: April 1, 2008
Citation: Callaway, T.R., Edrington, T.S., Anderson, R.C., Genovese, K.J., Keen, J.E., Looper, M.L., Nisbet, D.J. 2007. Bacteriophage isolated from feedlot cattle can reduce Escherichia coli O157:H7 populations in ruminant gastrointestinal tracts. Foodborne Pathogens and Disease. 5(2):183-191.
Interpretive Summary: Bacteriophage are bacterial viruses that can kill specific strains and species of bacteria. Bacteriophage that kill E. coli O157:H7 were isolated from cattle feces. These phage were tested in sheep experimentally infected with E. coli O157:H7 to see their killing effect on E. coli O157:H7. Phage treatment reduced E. coli O157:H7 in the gut of sheep in the cecum and rectum. A ratio of phage to E. coli O157:H7 of 1:1 was found to be more effective at reducing E. coli O157:H7 populations than ratios of 10:1 or 100:1. Our results indicate that phages with activity against E. coli O157:H7 can be used as a method to reduce E. coli O157:H7 concentrations in sheep.
Foodborne pathogenic bacteria, such as Escherichia coli O157:H7, can live undetected in the gut of food animals and be spread to humans via consumption of contaminated meat, direct animal contact, or water runoff into drinking and crop irrigation water supplies. Bacteriophages are viruses that prey on bacteria, offering a natural, non-antibiotic method to reduce pathogens in animals and the food supply. In this research we show that a cocktail of phages isolated from commercial cattle feces reduced E. coli O157:H7 populations in the caecum and rectum of sheep where it had been experimentally introduced. In in vivo studies we found that our cocktail of phages reduced E. coli O157:H7 populations in both the caecum and rectum. This is in contrast to previous studies using phage derived from environmental sources. A 1:1 ratio of phage to bacteria was found to be more effective than either of the higher ratios of 10:1 or 100:1. Our results demonstrate that phage can be used as a pre-harvest intervention, but the phages must be selected based both on efficacy as well its ability survive in the anaerobic and highly competitive environment of the gut.