Validation of the 375 Gram Matrix Extension to Health Canada MFLP-38 Detection of Salmonella Species from All Foods and Environmental Surfaces Using the Bio-Rad iQ-Check® Salmonella II Kit

Introduction: Salmonella is recognized as one of the most prevalent causes of food poisoning. A single foodborne outbreak can bring unimaginable economic losses to manufacturing companies; indicating a need for fast and reliable methods. The Bio-Rad iQ-Check Salmonella II Kit is based on gene amplification and detection by the use of real-time PCR. The assay contains ready-to-use PCR reagents containing oligonucleotides specific for Salmonella, as well as DNA polymerase and nucleotides. The assay, in combination with the Free DNA Removal Solution (FDRS) step, inhibits the amplification of target DNA from non-viable cells, which will aid in reducing the amount of false positive results.

Purpose: The objective of this study was to conduct a matrix extension evaluation of the Health Canada MFLP-38 method, with and without the FDRS step. The MFLP-38 was compared to the method for 375 gram test portions of milk chocolate, raw milk cheese, leafy green mix, custard filled pastry, smoked turkey breast, peanut butter, breaded chicken nuggets, vanilla ice cream, and stainless steel environmental surface (4” x 4” test area), as part of the Health Canada validation process.

Methods: Forty-five unpaired samples for each matrix were evaluated (20 replicates were inoculated at a high inoculation level, 20 at a low inoculation level, and 5 remained uninoculated). After sample enrichment, test portions were evaluated by both the new and reference methods. Samples were confirmed following procedures in the Health Canada MFHPB-20 reference method.

Results: Results for the assay were compared to the MFHPB-20 reference method by POD statistical analysis following Annex 4.4. No statistically significant differences were observed between the new method and the reference method in the eight foods and one environmental surface.

Significance: The data from the study, within the statistical uncertainty, supported the product claims of the iQ-Check Salmonella II Kit in detection of Salmonella in the select food matrices and environmental surfaces analyzed.