Escherichia coli O157:H7: clinical, diagnostic, and epidemiological aspects of human infection.

E. coli O157:H7 is one of many E. coli organisms that contain genes encoding one or more toxins similar in structure and function to Shiga toxin. E. coli O157:H7 is the most frequently isolated diarrheagenic type of E. coli isolated in North America today; this pathogen can cause serious, even fatal disease. Syndromes caused by E. coli O157:H7 include diarrhea, hemorrhagic colitis, and HUS. Poorly cooked ground beef has been the most frequently implicated vehicle of transmission, but additional vehicles are being identified. Treatment consists of rehydration during hemorrhagic colitis and support of the patient during the multiple systemic complications of HUS. A policy of routine screening for E. coli O157:H7 in clinical microbiology laboratories, without reliance on the physician to request that this organism be sought or the technician to notice blood in the stool, is the most effective way to find cases. Timely and accurate diagnosis can prevent secondary transmission, avert unnecessary and possibly dangerous procedures and/or therapies, and detect continuing outbreaks. SLTEC strains other than E. coli O157:H7 may cause diseases similar to or less severe than those caused by E. coli O157:H7. At present, however, screening for such pathogens in clinical laboratories is too labor-intensive to be practical. Education and legislation should promote safe food-preparation and food-handling practices. Research should be directed at reducing the carriage of E. coli O157:H7 at its bovine source, minimizing the microbial content of food and water, and averting systemic microangiopathic hemolytic anemia after infection with this pathogen.