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Chapter 4 : Application of Bacteriophages to Control Pathogens in Food Animal Production
Category: Applied and Industrial Microbiology
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In research studies, phage therapy has shown some promise as an effective preharvest intervention by controlling food-borne pathogens in animals before they enter processing plants. Phage therapy is also an effective postharvest intervention, reducing pathogen contamination of foods. Studies have demonstrated that phage therapy is effective against a broad range of food-borne pathogens belonging to the genera Salmonella, Campylobacter, Listeria, and Escherichia. With the current concern over the misuse of antibiotics, and the development of antibiotic resistance in bacteria, phages may play a leading role as a new class of antimicrobials in the agricultural and food industries. Phages have been successful at reducing E. coli O157:H7 during in vitro studies. In vitro studies were used to determine the effects of simulated gastric fluid and bile salts on the viability of free and encapsulated phage. Researchers used a receptor-modeling procedure to produce a phage cocktail to reduce E. coli O157:H7 in cattle. This approach allowed the researchers to produce a phage cocktail that contained phages that used multiple different receptors on the cell surface. Unencapsulated Felix-O1 was found to be extremely sensitive to acidic environments and was not detectable after a 5-min exposure to pH values below 3.7. Bacteriophages were isolated at 10 days postinfection from the intestine and from pools of organs of bacteriophage-treated chickens. Approximately 170 bacteriophages with morphologies similar to T4 have been identified. Regardless of the remaining work to be accomplished, phages' general acceptance and use as antimicrobials appear to be closer to reality than ever before.