Saturday 24 March 2018

Guest Contributor: “Big 6” non-O157 STEC

Guest Contributior: Michael “Mick” Guerini, Microbiologist and Technical Writer

When can we be ready to detect the “Big 6” non-O157:H7 E. coli?

The USDA’s Food Safety and Inspection Service (FSIS) recently announced they will extend the agency’s implementation date for non-O157:H7 Shiga toxin–producing Escherichia coli (STEC) sampling and testing to June 4, 2012, from an initial March 5 start date .  The extension, according to FSIS, was announced to give establishments additional time to validate test methods and detect non-O157:H7 STECs prior to entering the stream of commerce.  FSIS plans to begin sampling both domestically produced and imported raw beef manufacturing trimmings and other raw ground beef components for the serogroups O26, O103, O45, O111, O121 and O145.

First, let us review some of the information commonly known about the STEC group of bacteria.  Shiga toxin 1 (stx 1), identical to Shigella dysenteriae toxin and Shiga toxin 2 (stx2), associated with Hemolytic-uremic syndrome (HUS) (1000x more toxin than Stx 1) are very important for determining virulence.  Intimin (eae) and Heamolysin (hly) play a role as well.  Testing for a group of STECs is quite different from testing for a single organism like E. coli O157:H7.  The complexity in testing comes from having six different serogroups (O groups) that all require unique selective strategies for detection. 

How prevalent might these non-O157 STEC be in meat or other foods and are the diagnostics reliable?

Predictions from some industry experts suggest that the potential positive rate for beef trimmings may be as high as 4 to 10 percent.  Some are commenting on the lack of robust diagnostics, cost to consumers and questioning the relevance of this testing program for human safety.

Well the question comes down to when can we be ready for this new testing?

Interestingly, Costco, has been testing for non-O157 STECs in ground beef since August 2010, almost two years ahead of the program implementation (According to Costco’s director of food safety, Craig Wilson). Costco says that since they sample so much meat in any given day, they can easily spread out testing costs.  On the other hand, the American Meat Institute (AMI) lauded the delay in implementation as a “good first step,” the group also again criticized the new policy.  “Even with a 90 day delay, imposing this new regulatory program in June puts the cart before the horse and will needlessly cost tens of millions of federal and industry dollars – costs that likely will be borne by taxpayers and consumers,” added James Hodges, executive vice president at AMI.  “In short, the policy is not likely to yield a significant public health benefit and given that research should precede and dictate the policy, the process that FSIS has followed in this matter is no way to develop good public policy.”

So one group is already testing while another suggests the testing will not likely yield a significant public health benefit.  We all know that even one death is unacceptable when it comes to food safety.

What are we to do to get ready?

1) Continue researching the best ways to detect these “Big 6”.

2) Develop rapid and quality tests to detect the “Big 6”.

3) Fast-track studies on interventions to make sure there are ways of killing the “Big 6” during processing.

4) Continue an open dialog on how companies, the US Government and the general population will benefit from these tests.

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