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 E. coli O157:H7 Populations in Ruminants


Bacteriophage (viruses that infect bacteria) or phage have been used successfully in several in
vivo research studies to reduce the effects of diseases that impact production efficiency and
health in swine, sheep and poultry. Recently, it has been suggested that bacteriophage might be
an effective means to control E. coli O157:H7 in food animals prior to harvest. Cattle harbor
bacteriophage in their gastrointestinal tracts that specifically target E. coli O157:H7. Past
research isolated 30 phage that in a laboratory setting killed E. coli O157:H7 sourced from
commercial feedlot cattle feces. <P>
In preliminary studies, several naturally occurring bacteriophage active against E. coli O157:H7
were isolated from sheep from around the U.S., which indicated that bacteriophage are naturally
harbored by ruminants. The objective of this research was to better understand the ecology of
naturally occurring bacteriophage and their ability to be used as a preharvest intervention. <P>
Researchers sought to determine: <br/>
1. How widespread bacteriophage specific to E. coli O157:H7 are in cattle in production
situations <P>
2. The ability of E. coli O157:H7 bacteriophage to be used to reduce pathogen populations
in vitro<P>
3. The ability of E. coli O157:H7 bacteriophage to be used to reduce pathogen populations
in sheep

More information

Findings: The phage treatment was most effective against E. coli O157:H7 24 hours immediately following
treatment and a lower dose produced more desirable results. The treatment did show some
promise as an intervention method, but only in a multi-hurdle strategy. Proponents of
bacteriophage as an intervention have focused on the potential transmissibility of phage between
animals and the ability of phage to colonize an environment for long periods of time. The results
from this study disagree with those assumptions, as the bacteriophage did not colonize the
gastrointestinal tract to an extent great enough to prevent E. coli O157:H7 populations from
returning to “normal” levels.

<P> For complete projects details, view the <a href="…; target="_blank">Project Summary. </a>

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