A Canadian firm, Ranchers Beef, Ltd., is the likely source of the E. coli O157:H7 that caused 100 reported illnesses in the U.S. and Canada and led to the closure of Topps Meat Company in the U.S. in October. That's according to a joint investigation between the Canadian Food Inspection Agency (CFIA) and the USDA's Food Safety and Inspection Service (FSIS).

CFIA provided FSIS with DNA fingerprints from tests of beef trim from the Balzac, Alberta firm, which provided product to Topps. FSIS found the DNA pattern matched those from patients and from positive tests conducted by the New York Department of Health on recalled product.

FSIS delisted Ranchers Beef, Ltd., on Oct. 20, banning any product from that firm from coming into the U.S.