E. coli By Another Name Is Just As Deadly

November 1, 2009

E. coli O157:H7 deserves its reputation as a killer. Roughly 5-10% of children who are infected with this microbe develop hemolytic uremic syndrome (HUS). And 5-10% of the people who develop HUS die as a result of its devastating effect on the kidneys and other vital organs. Those who survive face life-long, often debilitating, complications.

The severe symptoms caused by E. coli O157:H7 are due to its production of two toxins – "shiga toxins" – related genetically to toxins produced by Shigella bacteria. Thus, E. coli O157:H7 is sometimes referred to as STEC, which stands for "shiga toxin-producing E. coli."

USDA has long treated E. coli O157:H7 as an adulterant in ground beef. Recently, this policy was extended to include beef trim and beef cuts. But E. coli O157:H7 is not the only E. coli that produces shiga toxins. There are other shiga toxin-producing E. coli that are equally capable of causing severe illness and even death.

• The E. coli outbreak that occurred in Oklahoma in 2008 was due to E. coli O111. Three hundred and forty-one people were infected; 72 were hospitalized; one person died.
• E. coli O45 was responsible for a 2005 outbreak that sickened 52 prisoners at a state correctional facility; 3 were hospitalized.
• At least 150 different STEC E. coli serotypes have been implicated in diarrheal illness in the United States. The most common, in addition to O157:H7, are: O26, O45, O103, O111, O121, and O145.

It's time to rethink E. coli from the name up. Microbiologists refer to the normal, non-pathogenic E. coli that lives happily in the intestines as "generic E. coli" – a meaningless name. Other E. coli types are referred to as "enteropathogenic" or "enterotoxigenic" or "enterohemorrhagic" or "STEC", depending on the way in which they cause illness.

I propose, instead, that we subdivide E. coli into four well-defined varieties:

• E. coli var. innocua (the innocuous bugs that lives comfortably inside all of us)
• E. coli var. enteropathogenica (E. coli types that behave similarly to Salmonella)
• E. coli var. enterotoxigenica (E. coli types that produce a toxin in food; people are sickened by ingesting the preformed toxin)
• E. coli var. shigelloides (shiga-toxin producing E. coli)

It's time we removed our blindfolds and recognized that E. coli O157:H7 is just one out of many disease-causing types of E. coli. Validated rapid tests to detect E. coli var. shigelloides are readily available today. There is no excuse for foot-dragging.

USDA and FDA must stop concentrating solely on E. coli O157:H7 and must expand their regulatory and enforcement activities to include all E. coli var. shigelloides.