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From: Food Quality & Safety magazine, February/March 2012

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

by Gina Shaw

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.”

“Most people focused primarily on O157:H7 after the 2006 spinach outbreak....But after we performed our own analyses, it was very evident that O157 was only one of several pathogens of concern with fresh produce.”

—Will Daniels, vice president, Earthbound Farm

Earthbound still uses the same “test and hold” approach it adopted six years ago. “All raw material, as it comes into our facility, is placed on hold, and we segregate production units from the field into four pallets,” Daniels explained “We take a representation from each of four pallets to make a test sample.” The testing process has three components: In addition to raw materials, finished products are also tested for pathogens, including non-O157 STECs; “input testing” is also performed for materials on the farm.

“Water, seeds, soil amendments, transplants, even water—anything we’re putting into the field is tested for the presence of pathogens,” said Daniels. “We require a certificate of analysis for fertilizer, and water is screened throughout the growing cycle. Our aim is to identify these issues as far upstream as possible.”

Daniels said Earthbound’s testing results at IEH jibe with the CDC’s recent findings: Collectively, non-O157 STECs outnumber O157 (as well as any other foodborne pathogen) within Earthbound’s crops.

“Others in the produce industry will say, ‘Well, with the amount of product you’re finding positives in, why aren’t we seeing recalls every other day?’ I think the beef industry has the same level of skepticism with regard to the Big Six,” Daniels said. “But I would argue that there’s ample evidence showing that people are getting sick from the Big Six. There’s no question that we need more data on prevalence and risk, but they are out there, and we need to be concerned about them. I would much rather be ahead of the problem on this one than trying to clean up the mess.”

Dr. Samadpour conceded that testing for the Big Six will add time to the process: “Will it inconvenience industry when the number of presumptive positives goes up and you have to add that further four hours of confirmatory testing? Yes, but the good news is that the same things that control O157 will control the non-O157s. So feedback to production can control these pathogens effectively, if you have that information.”

Other companies have also rolled out non-O157 STEC tests within the past year, including Aegis Food Testing, Food Safety Net Services, and BioControl.

But at least one leading food safety expert thinks the meat industry isn’t unreasonable in asking for a delay on implementing Big Six testing. “It’s a pity that FSIS has gone in this direction so quickly, because it’s not practical to implement the changes this soon,” says Michael Doyle, PhD, Regents Professor of Food Microbiology and director of the Center for Food Safety at the University of Georgia in Griffin. “Current testing protocols still involve a high percentage of false positives—as much as 10%. That’s not practical for the industry to implement right now.”

Dr. Doyle predicted that at least one new protocol for non-O157 STEC identification will be on the market within the year and that it will dramatically minimize false positives. But at this point, he said, “The agency’s ahead of itself.”

Earthbound’s Daniels praised the FSIS for implementing the ban on the Big Six in beef. “I understand that people are concerned about methodology from labs and making sure that they’re targeting the Big Six and not a broader category,” he acknowledged. “There’s still trepidation about what it means to industry and how much they’re going to have to divert. But I think it will be a positive step.”

He urged his own colleagues in produce to follow the meat industry’s lead. “I think that we’re probably 10 years behind the meat industry with regard to pathogen testing generally, not just with regard to non-O157 E. coli, and I hope that we come along faster and don’t wait for regulation or more crises to take action.”

 


Gina Shaw writes Food Quality’s enewsletter.

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