Validation of a New Molecular Detection System for the Detection of Listeria in Meat, Seafood, Dairy and Retail Environments

Introduction: There is a continued need to develop improved rapid methods for detection of foodborne pathogens in the food processing environment, raw materials, and finished products. The 3M™ Molecular Detection System utilizes isothermal DNA amplification and bioluminescence to detect targeted pathogens, after an enrichment step. 

Purpose: The project aim was to evaluate the new molecular detection assay for Listeria and to compare turnaround time and sensitivity to FDA-BAM standard methods, using environmental samples obtained from retail delis and meat, seafood, and dairy processing plants.

Methods: Environmental samples were collected using sponge-sticks with D/E Neutralizing Broth and tested for Listeria with the respective FDA-BAM standard methods and the 3M molecular detection system after 22 and 48 h enrichment in new modified Listeria Recovery Broth. Isolates from positive samples were confirmed by PCR; sequencing of the partial sigB gene was performed to characterize Listeria.

Results: Among the 341 samples tested for Listeria, 72 were positive by the new molecular detection system and FDA-BAM; 262 were negative by both methods; 2 were positive by the molecular detection system and negative by FDA-BAM (enrichments were retested using the molecular detection system and plated to LMPM and MOX for confirmation); and one sample was negative by the molecular detection system and positive by FDA-BAM. There were no significant differences between Listeria-positive samples detected by the molecular detection system and FDA-BAM standard methods (P = 0.945).

Significance: Overall, the 3M Molecular Detection System shows promise for application for rapid testing of environmental samples.