Evaluation of the MALDI-TOF-MS for the Detection of Listeria Monocytogenes in Ready-to-Eat Food Products

This proposal will evaluate the use of the MALDI-TOF-MS system to detect L. monocytogenes in high-risk foods (HRFs) such as Ready-to-Eat (RTE) imported foods that may be eaten uncooked (e.g., preserved fish, deli meats) or re-heated ( e.g. frankfurters) or eaten raw ( fruits, vegetables like sprouts). L. monocytogenes has the ability to grow in cold storage or refrigerator temperature where RTE food products, imported or locally made (cheese, deli meats, preserved fish, cooked-ready-to-eat crustaceans, etc.) are stored. Method: MALDI-TOF-MS technology will be used to identify L. monocytogenes directly from a selective enrichment broth that has been incubated for 30 hours to allow the organism to grow and multiply in numbers that can be detected without culture and isolation on a plated media. We will demonstrate that the MALDI-TOF-MS system identifies L. monocytogenes through laser desorption ionization of the sample attached to a matrix crystals. This process generates a unique mass spectral pattern or fingerprint that can be used to compare with reference libraries in the MALDI-TOF-MS system database to identify the microorganism. Significance and Impact of the Study: It is critical to have a rapid method to detect L. monocytogenes because of its ability to grow in cold storage or refrigerator temperature where RTE food products, imported or locally made are stored. The HRF designation of RTE foods is based on several factors as defined in Section 204 (d) (2) (A) of the Food Safety Modernization ACT (FSMA). Rapid detection of L. monocytogenes from contaminated RTE imported foods is critical in preventing the distribution of RTE food/food products contaminated with L. monocytogenes that continues to continuous to proliferate/multi[ply while in storage.