Survey of Listeria monocytogenes in ready-to-eat foods.

The purpose of this study was to develop data on the risk of listeriosis to support a science-based strategy for addressing Listeria monocytogenes in foods in the United States. Eight categories of ready-to-eat foods were collected over 14 to 23 months from retail markets at Maryland and northern California FoodNet sites. The product categories included luncheon meats, deli salads, fresh soft “Hispanic-style” cheeses, bagged salads, blue-veined and soft mold-ripened cheeses, smoked seafood, and seafood salads. The presence and levels of L. monocytogenes in the samples were determined by rapid DNA-based assays in combination with culture methods. Of 31,705 samples tested, 577 were positive. The overall prevalence was 1.82%, with prevalences ranging from 0.17 to 4.7% among the product categories. L. monocytogenes levels in the positive samples varied from 102 CFU/g, and the re...