Following identification of 4 patients in Edmonton, Alberta in September 2012 who were infected with E. coli O157 after consuming steaks purchased at Costco and manufactured by XL Foods, Inc. Public health investigators in Canada learned of additional patients in 4 provinces. By November 1, 2012 case-patients in Alberta (n=7), Newfoundland and Labrador (n=1), Quebec (n=6), and British Columbia (n=3) were linked to XL Foods produced beef. A steak provided by patient in the original group of 4 ill persons was positive for the outbreak strain of E. coli. The Canadian Food Inspection Agency (CFIA) isolated E. coli O157 in a sample of raw beef trimmings produced at the Brooks plant on September 4 but did not issue an alert. In addition that same day the USDA found a positive E. coli O157 sample in XL Food Inc. beef trim. The USDA found E. coli O157 in two more samples on September 12.