Minor modification to official method 2000.14, Reveal for E. coli O157:H7 test in selected foods and environmental swabs (20-hour method): validation of the test for 375 g raw beef samples.

A lateral flow immunoassay for Escherichia coli O157:H7 (Reveal E. coli O157:H7, 20-h version), previously validated for 25 g raw ground beef, raw beef cubes, apple cider, lettuce rinse, and environmental swab samples, has been validated for use in testing 375 g samples of raw ground beef and raw beef cubes. The Reveal method, including culture confirmation of positive immunoassay results, was evaluated in comparison to the current reference culture procedure of the U.S. Department of Agriculture-Food Safety and Inspection Service. For raw ground beef, the Reveal and reference methods produced the same number of confirmed positive results. For raw beef cubes, the Reveal method produced more positives than the reference method, but this difference was not statistically significant. The Reveal method exhibited 100% specificity, with no false-positive results obtained on uninoculated control samples. It is recommended that this minor modification to Method 2000.14 be adopted Revised First Action.