USDA Requirement to Test Beef for Non-0157 Strains of E. coli Faces Challenges

Within the next few days or the next few months—depending on whether or not industry challenges to implementation of the rule are successful—U.S. beef producers will be required to test their meats not only for the well-known pathogenic strain of E. coli known as 0157:H7, but also for six other strains of the bacteria known to cause illness in humans.

These other Shiga toxin-producing E. coli, or STECs, which include E. coli 026, 011, 0103, 0121, 045, and 0145, are collectively known as “the Big Six” and will, for the first time, be banned from meats sold in the U.S.

March 5 is the official launch of the FSIS’s mandatory sampling program for these pathogens, but representatives of the meat industry have repeatedly asked for a delay in this deadline, citing problematic testing protocols and unknown costs of implementation.

2010 marked the first year that non-0157 STECs collectively caused more illnesses overall than 0157:H7, according to a study released by the CDC in June. The non-0157 STECs caused 451 confirmed infections in 2010, including 69 hospitalizations and one death. E. coli 0157:H7, while associated with slightly fewer infections—442 in all—still led to nearly three times as many hospitalizations (184) and two deaths.

Combine that finding with the ongoing fallout from the massive, deadly summer 2011 outbreak of E. coli in Germany ultimately traced to sprouts (although caused by the rare 0104:H4 strain), and it’s little wonder that it’s not only the meat industry, under the gun as it faces the new regulations, but also the produce industry contemplating how best to implement testing for these previously unheralded pathogens.

Big Six strains of E. coli are famously harder to identify than 0157:H7. Fewer tools are commercially available for every step of the process, from enrichment to PCR screening to plating media. But that is rapidly changing, said microbiologist and food scientist Mansour Samadpour, PhD, president and CEO of IEH Laboratories and Consulting Group in Seattle: “Look back 10 years ago and we had the same situation with 0157:H7. Our testing for that strain has improved tremendously compared to the way it was done in 2002. About a year ago, manufacturers started to realize that there is a niche here (in testing for non-0157 STECs), and there has already been major growth in the market, with many companies now offering kits.”

Dr. Samadpour’s lab was ahead of the curve on the Big Six. “We developed our process several years ago,” he recalled. IEH began testing for these non-0157 E. coli strains in produce in 2006, in the wake of a major outbreak of E. coli in spinach. “When we had the spinach outbreak, and I started working with this industry, the pathogen list that I put together did include the non-O157s. That was promoted by Costco, and they and a few other retailers included those in their standards. Most of the testing we do for that industry has already included non-O157s.”

Dr. Samadpour said IEH’s PCR analysis process for these known pathogenic E. coli variants, which involves the detection of serotype-specific genes as well as other virulence genes, takes between 12 and 16 hours—12 hours for a negative result, with an additional four hours required for the follow-up enrichment and isolation necessary to confirm a positive.

One of Dr. Samadpour’s leading clients, and an industry leader in tracking non-O157 STECs, is California’s Earthbound Farm Organic, a pioneer in the organic produce industry.

“Most people focused primarily on O157:H7 after the 2006 spinach outbreak,” said Will Daniels, Earthbound’s vice president for quality, food safety, and organic integrity. “That’s what the Leafy Green Marketing Agreement (LGMA) was formed around. But as we performed our own analyses, it was very evident that O157 was only one of several pathogens of concern with fresh produce. So we decided to broaden our scope and include all pathogens of concern that we had the opportunity to test for back in 2006.”