Isolation and characterization of bacteriophages against Escherichia coli O157:H7 isolated from commercial feedlot stock pens across the Southern Plains States

ANNA CASTANO1, REBECCA OOT1, CARA FINK1, MARSHALL THOMAS1JOE JARDINE1, CARLY ALLEN1, TAKEHIRO YABANA1, JESSICA DAHL1TODD R. CALLAWAY2, RAUL RAYA1,3, ELIZABETH KUTTER1 & ANDREW D. BRABBAN1

Edinburgh, Scotland

Congreso; Bacteriophage evolution, ecology and applications.; 2005

Escherichia coli O157:H7, one of today’s leading public health concerns, is a food-borne pathogen that lives commensally in the guts of ruminants. Cattle are a major reservoir leading to human exposure; a survey published in 2001 estimated as many as 80% of feedlot cattle shed O157:H7 in the summer months. The focus of this research is to isolate and characterize bacteriophages that infect O157:H7, estimate their geographic distribution and develop a preharvest intervention strategy to control the entry of O157:H7 into the human food chain. Forty-nine phages active on E. coli O157:H7 were isolated from 120 samples of cattle feces collected from commercial feedlot pens across the southern plains states (USA). Screening for  phages was done by enrichment on E. coli B and on a nonpathogenic E. coli O157:H7 strain NCTC 12900. The most efficient phages were single-plaque purified and characterized by pulse-field gel electrophoresis, host range, PCR, infection profile and electron microscopy. All are exclusively lytic, have a range of genome size, and distinct host ranges on the ECOR collection. Under aerobic conditions, most lyse 12900 cells in 30 min in rich media. Further experiments are being carried out to evaluate their effectiveness in cocktails and under anaerobic conditions.