Performance Assessment of the Thermo ScientificTM SureTectTM Salmonella species Real-time PCR Assay According to the ISO 16140 Standard for Salmonella spp. Detection in Food and Pet Food

Introduction: The Thermo Scientific^TM SureTect^TM Salmonella species Real-Time PCR Assay is a new detection method based on real-time PCR. The oligonucleotides target unique DNA sequences found only in the target micro-organism and use PCR technology to amplify and detect them. If present, the target DNA is amplified and the increasing fluorescent signal is detected by the Thermo Scientific PikoReal Real-Time PCR instrument and interpreted by the Thermo Scientific SureTect Software.

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 alternative method includes a single enrichment step. Different protocols are available depending on the tested food matrices. After DNA extraction, PCR is run on the PikoReal instrument.

Results: 442 samples were analyzed to determine the relative accuracy, sensitivity and specificity of the alternative method. The results demonstrate equivalent performance between the alternative method and ISO 6579. Depending on the tested (matrix/strain) pairs, the relative detection limits of the alternative method vary from 0.2 to 1.5 CFU/25 g, those of the ISO standard vary from 0.2 to 1.1 CFU/25 g. The selectivity and the specificity of the alternative method were assessed by testing 51 target strains and 30 non-target strains. The alternative method was also evaluated in a ring trial involving 10 laboratories. The results of the calculated accuracy, accordance, concordance and odds ratio clearly show that the alternative method precision is equivalent to ISO 6579.

Significance: The SureTect^TM Salmonella species Real-Time PCR Assay is a reliable method for Salmonella spp. detection in food and pet food, and offers important economic savings by reducing time to result and handling time.