The US Department of Agriculture Food Safety and Inspection Service (FSIS) said that Town and Country Foods, in Maine, had discovered the bacterium during routine lab-testing, but had already sent out contaminated meat to retailers and wholesalers.
Although there have been no reported cases of illness from the products so far, questions have been raised about why the company sent out the meat without waiting for the lab tests to come back.
E Coli O157:H7 is a deadly bacterium, which can cause diarrhoea, dehydration and kidney failure in severe cases.