Performance of the 3M™ Molecular Detection Assay Listeria as Compared to the Canadian Reference Method MFHPB-30

Introduction: In recent years, about 132 cases of listeriosis on average were reported annually in Canada. Listeria is frequently associated with environmental contamination within food production facilities and is a significant food safety concern and cost. The 3M™ Molecular Detection Assay Listeria is used with the 3M™ Molecular Detection System for the rapid and specific detection of Listeria spp. in enriched food and environmental samples. The Molecular Detection Assays employs isothermal amplification of nucleic acid sequences to achieve specificity, efficiency and rapidity, utilizing bioluminescence to detect the amplification of the target.

Purpose: The objective of this study was to evaluate the performance of the Molecular Detection Assay Listeria spp. against the Compendium of Analytical Method MFHPB-30 in a variety of environmental surfaces for the inclusion in the Compendium of Analytical Method as a Laboratory Procedure (MFLP).

Methods: The method and comparative reference method (MFHPB-30) were analyzed by testing 9 typical food environmental surfaces (Stainless Steel, Plastic, Ceramic, Rubber, Food-grade painted surfaces, Wood, Sealed concrete, Cast iron, Air filter material). Three separate inoculum levels were used; 20 samples at 1-5 CFU/25 g, 20 samples at approximately 1 log CFU/25 g higher, and 5 negative controls.

Results: Statistical analysis was conducted using the Probability of Detection (POD) statistical model and showed perfect performance, exceeding the criteria outlined in the Health Canada MMC.

Significance: The Molecular Detection Assay Listeria spp. showed excellent performance and exceeded the Canadian requirements of the MMC. Additionally, modifications to the method (shorter handling times, lower enrichment volumes, shorter stomaching times) offers the capability of detecting Listeria spp. in environmental samples rapidly and effectively over other methods.