Difco™ E. Coli O Antiserum O157 and Difco E. Coli H Antiserum H7 are used for identifying Escherichia coli O157:H7.

E. coli O157:H7 is a foodborne pathogen that can cause potentially fatal enteric-related disease in humans.^1-7 This disease is characterized by sudden onset of severe cramps and abdominal pain, followed by a watery stool that may become markedly bloody. A series of 107 outbreaks involving 387 persons was traced to imported Camembert cheese in the United States in 1971.⁸ E. coli O157:H7 was recognized as a cause of hemorrhagic colitis in 1982⁴ and hemolytic uremic syndrome in 1983.⁹ The 1982 outbreak was derived from ingested hamburgers.^4,10

The incidence of disease caused by this organism has increased significantly over the past decade.^3,11 The largest outbreak of E. coli O157:H7 disease occurred during January 1993, in Washington State where more than 600 patients with hemorrhagic colitis were confirmed.¹ The source of the outbreak was identified as undercooked hamburger at multiple outlets of the same fast food restaurant chain.

E. coli O157:H7 is an enteric pathogen that requires only a low inoculum to cause disease. Transmission is usually via high-volume food items whose preparation is not always under stringent control and is served to a target audience (children and the elderly are most at risk for complications of the illness). The organism has been isolated from several foods, including undercooked hamburger, drinking water, new potatoes, turkey roll, raw milk and apple cider. Serotyping of the entero-hemorrhagic E. coli is useful in the epidemiological documentation of the spread of a particular strain in a foodborne outbreak.¹¹