Emerging foodborne pathogens: enterohemorrhagic Escherichia coli

In 1982, a new pathogen caused an outbreak of hemorrhagic colitis in this country. This new pathogen, Escherichia coli O157:H7, was not a known enteropathogen prior to this time. Since 1982, this organism has become the most commonly isolated pathogen from patients with bloody stools. Health officials estimate that E. coli O157:H7 causes 20,000 cases of hemorrhagic colitis annually in the U.S. Approximately 5% of all hemorrhagic colitis patients experience serious sequelae involving hemolytic anemia, thrombocytopenia, and kidney failure, and about 250 patients die each year with E. coli O157:H7 hemorrhagic colitis and sequelae. Even as many clinical laboratories become more efficient at detecting E. coli O157:H7 using simple media, other strains of enterohemorrhagic E. coli are appearing as causes of hemorrhagic colitis and hemolytic uremic syndrome. These non-O157:H7 are more difficult to detect and identify, and present a challenge to clinical microbiologists.