Purpose: An independent study was conducted at ADRIA, to validate this new method in comparison to the ISO 6579 standard, as part of the NF VALIDATION approval process and according to the ISO 16140 standard.
Methods: The 3M™ Molecular Detection Assay Salmonella test protocol includes a single enrichment step in Buffered Peptone Water (ISO). Two incubation temperatures are validated depending on the tested food categories (37°C and 41.5°C). After lysis, DNA amplification is performed in the 3M™Molecular Detection Instrument.
Results: 325 food and environmental samples were analyzed for relative accuracy, sensitivity and specificity study. The results demonstrate equivalent performances between the 3M™ Molecular Detection Assay Salmonella and the ISO 6579 methods. Depending on the tested (matrix/strain) pairs, the relative detection limits of the 3M Molecular Detection Assay Salmonella method vary from 0.3 to 2.0 CFU/25 g, those of the ISO standard vary from 0.3 to 1.8 CFU/25 g. The selectivity and the specificity of the alternative method were assessed by tested 50 target strains and 30 non target strains. The 3M™ Molecular Detection Assay Salmonella method was also evaluated in a ring trial involving 15 laboratories. The results of the calculated accuracy, accordance, concordance and odds ratio clearly show that the 3M™ Molecular Detection Assay Salmonella method precision is equivalent to the ISO 6579 standard.
Significance: The alternative method is a reliable method for Salmonella spp. detection in food and environmental samples, and offers important economic savings by reducing time to result and handling time.