Hospital outbreak of Escherichia coli O157:H7 associated with a rare phage type--Ontario.

Since the early 1980s, verotoxigenic Escherichia coli serotype O157:H7 has emerged as a major cause of both sporadic and epidemic disease in North America and other regions of the world. Most infections result in mild diarrhea but more serious illnesses include hemorrhagic colitis, hemolytic uremic syndrome, and thrombotic thrombocytopenic purpura. Outbreaks of E. coli O157:H7 infection have occurred in various settings including schools, day-care centres, and nursing homes. Most outbreaks and sporadic cases have been associated with the consumption of foods of bovine origin, particularly undercooked ground beef. This report presents findings of the investigation of an unusual outbreak involving the patients and staff members of a suburban acute-care hospital in southern Ontario.