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United States Department of Agriculture

Agricultural Research Service

Title: Isolation of Naturally-Occurring Bacteriophage from Sheep That Reduce Populations of E. Coli 0157:h7 in Vitro and in Vivo

item Callaway, Todd
item Edrington, Thomas
item Anderson, Robin
item Jung, Yong Soo
item Genovese, Kenneth
item Elder, Robert
item Nisbet, David

Submitted to: International Symposium and Workshop on Shiga Toxin ... Escherichia coli
Publication Type: Abstract Only
Publication Acceptance Date: August 20, 2002
Publication Date: N/A

Technical Abstract: Bacteriophage that specifically target bacteria have been used to treat bacterial infections in humans as an alternative to antibiotics. Previous research has examined the use of bacteriophage to control food-borne pathogenic bacteria in food animals, however results have been inconclusive. Sheep (n=32) were transported from open range pasture to College Station, TX. Feces were collected and enriched for bacteriophage via standard procedures and 46% were positive for naturally-occurring bacteriophage. A phage (CEV-1) was isolated into pure culture via filtration prior to further characterization. Microscopic examination revealed that the phage had characteristic T-even phage morphology. Molecular studies indicated that the genome was approximately 180 kb in size and that the capsid protein shared 94% homology with the gp23 capsid protein of T4 bacteriophage. CEV-1 bacteriophage killed strains (n=18) of E. coli O157:H7 as well as K-12, O43:H7, O126:H7, O158:H7 and Omulti:H7 in in vitro activity assays; however other bacterial species (e.g. Salmonella, Streptococcus) were not affected by this phage. Treatment of pure cultures of E. coli O157:H7 with CEV-1 in a 10:1 PFU/CFU ratio resulted in a rapid (6 h) significant (P < 0.05) decrease in concentrations of viable cells (10**8 to 10**4 CFU/ml). Addition of CEV-1 to in vitro ruminal and fecal fermentations containing E. coli O157:H7 resulted in a reduction of approximately 2 log10 CFU/ml E. coli O157:H7. Sheep not naturally shedding bacteriophage (n=8) were experimentally challenged with E. coli O157:H7 and then inoculated with bacteriophage CEV-1. Concentrations of E. coli O157:H7 were numerically but not significantly (P>0.05) reduced (approximately 2 log10 CFU/g digesta) in the rumen, cecum and colon. Although it appears that bacteriophage treatment could be used to reduce E. coli O157:H7 in food animals, further research is crucial prior to implementation.

Last Modified: 4/22/2015
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