Agency Expects Faster E. coli O157:H7 Determinations
The Food Safety and Inspection Service began using new methods this year that are speeding up its analysis of samples that may be contaminated with E. coli O157:H7. The revised testing methodology, spelled out in a Federal Register notice yesterday, includes use of an improved enrichment broth and genetic testing to determine if the E. coli isolate is positive for Shiga toxin production, positive for the Shiga toxin gene, or genetically determined to be H7.
FDIS said its labs have been using the new methods since Jan. 28, 2008, and the methods are described in the Microbiology Laboratory Guidebook (MLG), Chapter 5.04. Interested parties may submit comments on the methods by Nov. 17, 2008, using www.regulations.gov and searching for docket number, FSIS-2008-0007.
Validation tests on the new broth by FSIS and the USDA Agricultural Research Service show that it supports faster growth of E. coli O157:H7 than the broth FSIS had used before. The new one is cost-effective and is used by many laboratories around the world for detecting E. coli O157:H7; it allows FSIS labs greater flexibility and allows screening tests to be conducted earlier on the second day of analysis because of a shorter incubation period. Its use will reduce the number of samples that must be discarded when there are shipping problems that delay the arrival of samples, FSIS said. Because the new procedure is more sensitive, there may be "some increase in the number of E. coli O157:H7-positive samples found by FSIS laboratories," the notice states.