Sporadic occurrence of hemorrhagic colitis associated with Escherichia coli O157:H7 in Newfoundland.

During a 9-month period in 1984, 113 fecal samples obtained from 92 patients with diarrheal illness were cultured for Escherichia coli serotype O157:H7 to determine the occurrence of this agent in diarrheal illness in Newfoundland. E. coli O157:H7 was isolated in almost pure culture from 12 stool specimens obtained from 7 (15%) of the 47 patients who had grossly bloody diarrhea; none of the 12 yielded any of the usual enteric pathogens. The agent was not isolated from the stool specimens obtained from the remaining 45 patients, who did not have bloody diarrhea. All seven patients whose specimens were positive for E. coli O157:H7 had clinical manifestations typical of hemorrhagic colitis, but the syndrome was clinically suspected and a specific test requested in only two cases. The seven cases were not clustered geographically or temporally, and no common exposure was identified. To determine whether hamburger meat was the source of E. coli O157:H7, 66 samples obtained from various retail outlets were tested; none were found to be positive. Hemorrhagic colitis may be a common disease, and E. coli O157:H7 should be considered as an agent in bloody diarrheal illness.