Control of enterohemorrhagic E. coli 0157:H7 in cattle by probiotic bacteria and specific strains of E. coli

DETAILED DESCRIPTION OF THE INVENTION Histologic examination of colonic tissue has revealed no evidence of attachment of E.
coli O157:H7 to bovine colonic tissue.
The rumen appears to be the most important site for long-term carriage of E.
coli O157:H7.
The presence of O157:H7 bacteria in the colon is considered to be a transient state, the bacteria passing through from the rumen source and being shed in feces.
Animals can be initially infected by ingestion of contaminated grass, feed or water.
Results of the present study demonstrate that E.
coli O157:H7 persists in the rumens of untreated calves up to 30 days after a single inoculant dose, and is shed in feces throughout the same time period.
The O157:H7 bacteria are therefore carried by cattle along with any other microbial strains that inhabit the animals'digestive tract.
For purposes of this invention, cattle and other animals in whose tissues or feces E.
coli O157:H7 can be detected are said to carry E.
coli O157:H7.
The amount of E.
coli O157:H7 carried by an animal is measurable in various ways, including sampling from various tissues.
Most conveniently, the presence of E.
coli O157:H7 can be measured in feces.
Such measurement is of practical importance, since fecal contamination is the apparent source of meat contamination and also of reintroduction and infection of other animals.
As shown herein, the amount of E.
coli O157:H7 shed in feces is reflected in the amount measurable in the rumen.
Therefore, the amount of E.
coli O157:H7 in feces is a measure of the amount carried by the animal.
Quantitative measurement of E.
coli O157:H7 is expressed as colony forming units (CFU) per g feces or per ml rumen.
"Probiotic" is used herein as an adjective to describe bacteria isolated from a natural source and having the property of inhibiting the growth of E.
coli O157:H7.
The test of an inhibition used herein was an in vitro test on solid medium in which culture supernatants of candidate isolated bacteria were observed for their property of inhibiting E