P3-11 A Complete AOAC-Approved Workflow for the Detection of Salmonella spp. in Pooled Food Samples

Wednesday, July 31, 2013
Exhibit Hall (Charlotte Convention Center)
Jason Wall, Life Technologies, Inc., Austin, TX
Rick Conrad, Life Technologies, Inc., Austin, TX
Introduction: The Pathatrix Auto™ pathogen isolation platform provides a workflow that is able to process volumes up to 50mL containing as many as ten individual food enrichments in the same sample pool.  This new workflow provides food producers with a PCR-based pathogen detection technology without the high costs associated with the traditional one-sample-per-assay-well relationship.

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.