An official website of the United States government.

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Isolation and Use of Bacteriophage to Reduce Escherichia coli O157:H7 in Ruminants


To isolate and characterize several E. coli O157:H7 infecting bacteriophage from feedlot manure and test their efficacy as a preharvest intervention strategy to reduce E. coli O157:H7 in ruminants.

More information

Findings: Cattle can carry E. coli O157:H7 in their gastrointestinal tracts. Cattle also carry bacterial viruses (phage) that specifically kill E. coli O157:H7. It has been suggested that we use these phage to kill unwanted E. coli O157:H7 before cattle are slaughtered. We isolated 30 phage that killed E. coli O157:H7 from commercial feedlot cattle feces. We used these phage to reduce E. coli O157:H7 populations in sheep. We reduced E. coli O157:H7 populations approximately 100-fold in the gastrointestinal tract. We also found that adding more phage is not necessarily better, a lower dose of phage was more effective in killing E. coli O157:H7 than a 100-fold higher dose. We found that phage treatment was most effective against E. coli O157:H7 in the 24 hours immediately following treatment. These results indicate that phage could be used as a method to reduce E. coli O157:H7 in cattle before slaughter, but unfortunately, phage treatment is not the �ultimate� solution that we in the beef industry have sought. However, utilization of phage as one treatment in a multiple intervention or hurdle scheme could be effective; especially given the prevailing trend to reducing the use of antibiotics in cattle.

Calaway, Todd
USDA - Agricultural Research Service
Start date
End date
Project number
Accession number