Performance of the 3M™ Molecular Detection Assay Salmonella as Compared to the Canadian Reference Method MFHPB-20

Introduction: The Public Health Agency of Canada estimates that about 11 million Canadians suffer from a food-related illness each year.  As of 2011, Salmonella continued to be the most common pathogen reported to the National Enteric Surveillance Program (NESP), a total of 6809 Salmonella isolates (19.68 per 100 000 population). The 3M™ Molecular Detection Assay Salmonella is used with the 3M™ Molecular Detection System for the rapid and specific detection of Salmonella 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 Salmonella against the Compendium of Analytical Method MFHPB-20 in a variety of food matrices for the inclusion in the Compendium of Analytical Methods as a Laboratory Procedure (MFLP).

Methods: The method and comparative reference method (MFHPB-20) were analyzed by testing 5 food categories with 3 matrices per category (ready-to-eat meat and poultry, fish and seafood products, dairy products, fruit and vegetable-based products, eggs and derivatives). 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 exceeded the criteria outlined in the Health Canada MMC. Additionally, Level of Detection (LOD) results showed a range of 0.312 – 3.2 MPN/25g. 

Significance: The Molecular Detection Assay Salmonella showed excellent performance and exceeded the Canadian requirements of the MMC. This new method offers the capability of detecting Salmonella species in foods after only 18-24 hours of incubation, thereby reducing presumptive reporting times over the reference method by almost 24 hours.