An Independent Evaluation of the GENE-UP Listeria monocytogenes Assay for the Detection of Listeria monocytogenes in Foods

Introduction: The persistence of Listeria monocytogenes to survive in extreme food manufacturing environments can cause severe problems in finished product for manufacturers. The number of people infected by foodborne L. monocytogenes is less than other foodborne pathogens; however, outbreaks from Listeria monocytogenes can produce high mortality rates. Foods such as raw milk cheeses, pasteurized dairy products, smoked seafood, ready-to-eat deli meats and cantaloupe have been implicated in such outbreaks. The GENE-UP^™ Listeria monocytogenes Assay is a Real-Time PCR assay designed to detect fluorescence at several wavelengths to allow for multi-target detection in the same reaction vessel. The assay uses dual Fluorescence Resonance Energy Transfer (FRET) hybridization probes to detect target analytes.

Purpose: To independently evaluate the alternative rapid method, to the USDA-FSIS 8.09 method for deli ham (25g), to the FDA/BAM Chapter 10 method for smoked salmon (25 g), and the AOAC 993.12 method for Mexican soft cheese (125 g) as part of the AOAC RI™ PTM validation process.

Methods: Using 30 unpaired samples for each matrix, 5 replicates were inoculated at a high inoculation level, 20 at a low inoculation level and evaluated along with 5 uninoculated control replicates. After sample enrichment in LPT Broth, test portions were evaluated by both the alternative and reference methods. Samples were confirmed following procedures outlined in the USDA/FSIS-MLG 8.09, FDA/BAM Chapter 10, AOAC 993.12, and bioMérieux’s alternative confirmation procedure.

Results: Results for the assay were compared to the MLG, FDA, and AOAC reference methods by POD statistical analysis. No statistically significant differences were observed between the new method and the reference methods in the 3 foods.

Significance: The data from the study, demonstrates that the GENE-UP Listeria monocytogenes Assay is a rapid and reliable method for the detection of Listeria monocytogenes in the food matrices analyzed.