Foodborne Illness:
  Non-O157 E. coli:
  The growing threat




Most people have heard of E. coli O157:H7–the lethal bacterium behind the 1993 Jack in the Box hamburger outbreak, which killed four children and sickened 720. Since then, E.coli O157 has triggered scores of outbreaks in undercooked ground beef and meat, raw milk, and fresh fruits and vegetables—including spinach, lettuce, cole slaw, and apple cider.

E. coli O157 is one of a group of bacteria known as STECs–for Shiga Toxin-Producing E. coli. Its toxin causes severe abdominal cramps, watery and sometimes bloody diarrhea, and in at least 5-10 percent of cases, Hemolytic Uremic Syndrome (HUS), which can kill its victims.

The good news is that, over the last 15 years, E. coli O157 infections have dropped by almost half. But another dangerous group of E. coli bacteria–known as non-O157 Shiga Toxin-Producing E. coli, or non-O157 STECs–now eclipse O157. According to the CDC, an estimated 265,000 STEC infections occur each year in the United States. E. coli O157, the threat we know well, causes about 36 percent of these infections–and non-O157 STECs, the threat we have ignored, cause the remaining 64 percent. These new strains have set off outbreaks through a wide variety of foods,  including ground beef, American cheese, strawberries, and packaged macaroni salad.

In the U.S., most non-O157 STEC strains belong to a group known as the Big Six. The Big Six are no strangers to U.S. public health experts, who have implicated the germs in outbreaks here since the mid-1990s. Today, the bacteria cause 70 to 95 percent of all non-O157 E. coli infections in this country. And according to the CDC, some of these strains are every bit as vicious as O157. With the rising caseload of Big Six infections, the CDC in 2009 recommended that clinical laboratories test all stool specimens for non-O157 STECs.

Yet there is only scant published research on how common these organisms are in the meat supply. A recent study from Texas Tech University found Big Six strains in 7 percent of retail ground beef and 4 percent of whole muscle cuts. A 2008 study, funded by Seattle food safety lawyer Bill Marler, found non-O157 STECs in 1.9 percent of ground beef sample–about 1 in every 50 packages.

Why have these organisms proliferated? The Big Six have been allowed to slip through the federal food safety net because our leaders have not treated these infectious agents with the same urgency as they have O157. In part, they have succumbed to industry pressure. The American Meat Institute (AMI) has fiercely resisted legislation that would declare non-O157 strains “adulterants.” Under USDA rules, any product that contains adulterants must not be sold, and the product must either be destroyed or cooked enough to kill the disease-causing organism.

USDA officials contend that they understand the threat. “My team here started working on this issue in the first week that I was on the job,” Elisabeth Hagen, the USDA’s Under Secretary for Food Safety, told Good Housekeeping. Hagen, who was appointed in 2010, had asked the White House Office for Management and Budget to approve designating the Big Six as adulterants. Finally, on September 12, 2011, the USDA announced its decision to extend the ban on E. coli in ground beef to include the Big Six.


Unless otherwise noted, all content about foodborne illness and food safety policy is written by Madeline Drexler, Schuster Institute senior fellow.

Copyright © 2011 Schuster Institute for Investigative Journalism at Brandeis University, Waltham, MA.

Last page update: September 16, 2011