Purpose: AOAC approval was recently obtained for this workflow which allows Food Safety professionals to utilize a sample pooling strategy prior to screening by Real-Time PCR. We demonstrate that this workflow can robustly process a diverse array of food sample types, has high fidelity in correctly detecting the presence of Salmonella, and is applicable to other bacterial pathogens of interest found in food.
Methods: The core technology is the automated isolation of pathogenic Salmonella serovars from food matrices by antibody-conjugated magnetic beads. The captured bead-bound bacteria are then lysed and the supernatant is added to a lyophilized Life Technologies MicroSEQ® Salmonella spp. Real-Time PCR assay previously validated by AOAC and AFNOR. Confirmation of sample calls was determined by selective plating and previously validated Life Technologies Real-Time PCR workflows.
Results: By combining the specificity of antibody-based capture and the sensitivity of Real-Time PCR, our workflow is able to reliably detect 1 CFU of Salmonella in 25-375g food product samples. A wide variety of sample types were tested in the course of this validation study. In all sample types tested, this workflow correctly identified all positive and negative samples (100% specificity and sensitivity; N=60 sample types, N≥20 enrichments per sample type to obtain fractional positives).
Significance: The ability to pool individual samples, in addition to the ease of use of this workflow, enables the processing of hundreds of samples per hour at a fraction of the cost of platforms that do not accommodate a pooled sample format. This creates an economic benefit to food producers by providing a workflow that is able to rapidly and inexpensively screen for rare contamination events. This work demonstrates that by using this workflow, one can attain equivalent-or-better results than traditional culture methods, in far less time, for a significantly less cost burden than other PCR-based platforms.