Study Objective: To describe the spectrum of illnesses associated with Escherichia coli 0157:H7 infections.

Design: Described an outbreak that showed the broad spectrum of these infections. Reviewed the clinical findings in the other eight major outbreaks reported between 1982 and 1986. Also reviewed reports of sporadic cases.

Setting: Outbreaks in communities, nursing homes, a day care center, and a kindergarten.

Cases: Persons identified in outbreaks of E. coli 0157:H7 infections.

Results: Escherichia coli 0157:H7 infection causes bloody diarrhea (hemorrhagic colitis), nonbloody diarrhea, the hemolytic uremic syndrome, and thrombotic thrombocytopenic purpura. Infection can be asymptomatic, can involve extraintestinal sites, and can be fatal. Bloody diarrhea is the commonest symptom. Most patients have severe abdominal cramps; fever is documented in less than half. Findings from fecal leukocyte examinations often suggest a noninfectious cause. Results of radiologic and colonoscopic examinations can be consistent with a diagnosis of inflammatory bowel disease or ischemic colitis. Patients at the extremes of age are at increased risk for E. coli 0157:H7-associated diarrhea, the hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, and death. Antimicrobial agents have not been shown to modify the illness, but there are few data on individual agents.

Conclusion: Infection with E. coli 0157:H7 should be considered in all patients with bloody diarrhea, the hemolytic uremic syndrome, or thrombotic thrombocytopenic purpura because the infection can masquerade as gastrointestinal bleeding of noninfectious cause, the antecedent diarrhea may be resolved and forgotten by the time the hemolytic uremic syndrome or thrombotic thrombocytopenic purpura is diagnosed, and the detection of E. coli 0157:H7 requires specific stool culture techniques.