Purpose: This study evaluated the performance of the 3M MDA Listeria monocytogenes for the detection of L. monocytogenes in various RTE products as compared to the standard FDA-BAM method.
Methods: Products (n = 200) were purchased from several different sized retail stores. These included 122 aquatic products (from fresh and salt water), 22 products of animal origin (e.g., smoked chicken wings), 18 vegetarian products (e.g., seasoned mushrooms), 13 salad and vegetable products, 15 deli meats, 4 desserts, 2 egg products, and 4 others. Each sample (approx. 100 g) was homogenized and screened for L. monocytogenes following the 3M MDA Listeria monocytogenes, and the FDA-BAM methods.
Results: Results from the two detection methods did not differ significantly (P > 0.05). Overall, 15/200 samples were positive for L. monocytogenes (7.5%). Five samples showed discrepant results; fermented pork and chicken tender sausages tested positive by the FDA-BAM method only. Fermented fish sausage, fried minced mushroom and fried tofu tested positive by the MDA only. The sensitivity of the MDA was 86.7% (95% CI: 58.4-97.7%), specificity was 98.4% (95% CI: 95.0-99.6%), accuracy was 97.5%, and the positive predictive value was 76.9% (95% CI: 46.0-93.8%).
Significance: The 3M MDA Listeria monocytogenes yields rapid and reliable results for the detection of L. monocytogenes in various food products. Detection and monitoring of L. monocytogenes in RTE products are important for the reduction of incidence of listeriosis outbreaks worldwide.