Colorado State University Extension
SafeFood Rapid Response Network


SafeFood Newsletter - Winter 1996/1997 - Vol. 1, No. 2

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Should We Be Looking for More than E. Coli O157:H7?

Is our preoccupation with E. coli O157:H7 putting us at risk of getting blindsided by other equally potent disease-causing strains of E. coli? Dr. David Acheson, infectious disease specialist with Tufts New England Medical Center, fears this may be the case. In his research Acheson suggests the best way to detect those E. coli strains most likely to cause illness is to look for the Shiga toxin gene--the common denominator among pathogenic E. coli.

Shiga toxin was identified 100 years ago as the cause of dysentery, and it has been found to be the source of many of our foodborne illness woes. Acheson has been studying the ability of the Shiga toxin gene to jump from one strain of bacterium to another, giving them the ability to produce toxin and cause disease.

Acheson, with the help of Meridian Diagnostics, has developed an enzyme immunoassay that can detect the Shiga toxin gene in food and stool samples. When he tried out his method, the Premier EHEC test, on ground beef samples from retail, he found 25 percent were contaminated with Shiga toxin- producing bacteria, none of which were O157:H7.

If there is an Achilles' heel to Acheson's approach, it is that we don't know how many Shiga toxin- producing bacteria are human pathogens. However, Acheson believes that the fact that 60-100 serotypes of E. coli have been found in patients with hemorrhagic colitis or hemolytic uremic syndrome (HUS) makes them "highly suspicious." He has suggested his method could be used by meat plants to catch and divert products most at risk of causing disease.

The Premier kit was approved for use in clinical labs by the FDA last year, and Meridian Diagnostics is wrapping up testing for AOAC International approval of the kit's use in foods.

Source: Food Protection Report, June 1996.

Updated Monday, August 29, 2011