USDA poised to start testing beef for non-O157 E coli


May 29, 2012 (CIDRAP News) – The US Department of Agriculture (USDA), poised to start testing beef trim for six non-O157 strains of pathogenic Escherichia coli next week, today released documents that spell out some expectations for the program and make clear that much remains to be learned about the risk.

In a notice to be published in the Federal Register, USDA officials responded to industry concerns about the testing program and said they expect it will make beef safer by prompting processors to make voluntary changes in their safety systems. The agency also released a revised edition of a risk profile for non-O157 in beef.

Beef industry officials had suggested that the USDA conduct more baseline studies of the prevalence of non-O157 Shiga-toxin–producing E coli (STEC) in beef before launching the program. But the agency said it's clear that the strains are present, although it's impossible to say how prevalent they are.

The USDA's Food Safety and Inspection Service (FSIS) plans to launch its testing program on Jun 4, after considering the step for about 4 years. The agency announced the plan last September and originally intended to start testing in March, but postponed it in response to industry concerns. Testing will target E coli O26, O45, O103, O111, O121, and O145, which are said to account for 80% of non-O157 E coli illnesses infections.

The Centers for Disease Control and Prevention has estimated that non-O157 E coli strains cause 112,000 illnesses annually. Of those, an estimated 36,700 are believed to be related to beef, USDA officials said when they announced the testing program in September.

For now the testing program will focus only on beef trim, which is used to make ground beef. Plans calling for extending testing to actual ground beef later.

The FSIS notice says many commenters asked the agency to delay the testing program to gather more baseline data on non-O157 STEC and make sure that test kits are commercially available.

But the agency concluded that "a baseline is neither necessary nor warranted" before starting the testing. "These organisms are present in beef products in the United States," as shown by evidence gathered by the USDA Agricultural Research Service in a limited number of slaughterhouses.

However, the FSIS does plan to conduct a prevalence study in 2013 of both E coli O157 and non-O157 STEC on beef carcasses, which will be sampled after hide removal but before decontamination steps, the notice says. The revised risk assessment acknowledges that the lack of baseline data rules out making definitive statements about the national prevalence of non-O157 STEC in beef.

At the same time, the FSIS estimates in the notice that 2% of beef trim samples will be positive for non-O157 STEC in screening (preliminary) tests, but a "significantly lower" percentage will be confirmed. "This is comparable with what happens in O157 testing," it says.

The FSIS rejected the objection from commenters that tests for non-O157 strains are not sufficiently available. Screening and confirmation tests are available, and reagents are available to companies that want to use the FSIS testing method, the agency said, adding that some facilities have been testing for a year or more.

Other commenters questioned the rationale for the testing partly on grounds that non-O157 strains tend to cause less-severe illness than O157, according to the notice.

The risk profile summary says most studies indicate that non-O157 STEC strains are less likely than O157 to cause severe illness or death, but it also states that some non-O157 strains "can cause permanent, life-threatening damage to major organ systems."

In responding to the comments, the FSIS said it expects that the testing program "will improve food safety because FSIS anticipates that establishments may voluntarily make changes to their food safety programs in response to the new testing."

For example, facilities may start their own testing program or may add new safety interventions, the notice says. "FSIS is aware that some companies have added new bacteriophage [viruses that attack bacteria] interventions to address non-O157 STEC."

The USDA notice also includes responses to concerns voiced by countries that export beef to the United States. The FSIS said it has made available to foreign governments reagents it uses in testing for non-O157 E coli, and it promised to treat beef imports tested for such strains the same way it treats imports it tests for E coli O157.

See also:

Advance version of USDA Federal Register notice

FSIS risk profile for non-O157 STEC

Sep 13, 2011, CIDRAP News story "USDA testing for non-O157 E coli to start with beef trim"

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