Enterohemorrhagic Escherichia coli O157:H7--an emerging pathogen.

Enterohemorrhagic Escherichia coli O157:H7 has become an important public health problem in recent years, causing more than 20,000 cases of infection and up to 250 deaths per year in the United States. Transmission of infection is most commonly linked to consumption of undercooked ground beef, contaminated drinking water or unpasteurized milk. Patients with this infection most often present with an acute onset of diarrhea and abdominal cramping that progresses over days to bloody stools. The most serious complications of E. coli O157:H7 infection include hemolytic-uremic syndrome and thrombotic thrombocytopenic purpura. Hemolytic-uremic syndrome occurs most often in children less than five years of age and the elderly, while thrombotic thrombocytopenic purpura occurs only in adults. Detection of E. coli O157:H7 requires specific testing that is not performed in routine stool cultures. All patients with documented infection require close observation for the development of possible complications. Use of antibiotics and antimotility agents may worsen the course of the infection and should be avoided.