Independent Evaluation of the Bio-Rad iQ-Check® Salmonella II Kit for the Detection of Salmonella Species in Select Foods and Environmental Surfaces

Introduction: Salmonella has been implicated as a main cause of foodborne outbreaks and detection can be time consuming and expensive. Manufacturers require methods that are rapid and reliable for the detection of Salmonella. The Bio-Rad iQ-Check Salmonella II Kit is a test based on gene amplification and detection by the use of real-time PCR. Ready-to-use PCR reagents contain oligonucleotides specific for Salmonella, as well as DNA polymerase and nucleotides. The Free DNA Removal Solution (FDRS) step removes DNA from non-viable cells leaving viable bacteria to be detected by PCR, which reduces the amount of false positive results.

Purpose:  This study independently evaluated the new method, comparing FDRS and without FDRS to FDA/BAM Chapter 5 method for milk chocolate (375 g), raw milk cheese (375 g), and stainless steel environmental surface (4” x 4” test area) and to the USDA/FSIS MLG 4.08 method for chicken carcass rinse (30 mL) as part of the AOAC RI™ PTM validation process.

Methods: Thirty unpaired samples were evaluated for each matrix (5 replicates were inoculated at a high inoculation level, 20 at a low inoculation level and 5 remained uninoculated (control) replicates). After sample enrichment, test portions were evaluated by both the new and reference methods. Samples were confirmed following procedures outlined in the FDA/BAM Chapter 5 and the USDA/FSIS-MLG 4.08.

Results:  Results for the assay were compared to the FDA and MLG reference methods by POD statistical analysis. No statistically significant differences were observed between the new method and the reference methods in the three 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 and enhanced sensitivity in detection of Salmonella in the select food matrices and environmental surfaces analyzed.