As “Big Six” Testing Mandate Begins, Non-0157 E. Coli Outbreak Hits

On June 4, the USDA officially expanded its raw beef testing protocol to include the so-called “Big Six” strains of E. coli that, collectively, cause more outbreaks of foodborne illness than the 800-pound gorilla of E. coli, 0157:H7. (0157:H7 still leads to more hospitalizations.)

On June 10, as if to underscore the importance of such testing, officials from the CDC officially announced that an E. coli outbreak in six states that has sickened 14 people so far and killed a 21-month-old girl in Louisiana has been identified as the 0145 STEC (shiga toxin-producing E. coli), one of the Big Six. The source of the outbreak has not yet been identified, the CDC said, but given the six-state spread of the outbreak, it seems likely to be a food source.

The CDC’s investigation began May 14, and illnesses related to the outbreak appear to have developed between April 15 and May 12. It has been approximately four weeks since the last illness onset among reported cases, but the CDC continues to investigate.

Although prevention of non-0157 STEC-related outbreaks may be improved by the new USDA inspection requirements, investigating such outbreaks remains challenging, because most clinical laboratories cannot identify non-0157 strains; instead, the samples must be sent to public health laboratories.

The CDC noted that the STEC O145 PFGE (pulsed-field gel electrophoresis) pattern in this outbreak had not been previously been seen in PulseNet, the national network of public health and food regulatory laboratories that performs regular surveillance of foodborne infections.

So far, the USDA’s Food Safety and Inspection Service has not actually begun surveying sites for compliance with the new testing requirements. That step will likely begin in September, after a 90-day period during which beef producers have been asked to collect data to support their non-0157 STEC controls.