Evaluation of Novel Real Time PCR Based Risk Assessment Tool – Enteric Pathogen Risk Indicator (EPRI)
Daniel R. DeMarco 1, Erica Miller 1, J. David Legan 2 and Joelle Mosso 3
Eurofins Microbiology Laboratories, Inc.: 1 Louisville, KY; 2 Madison, WI, 3 Fresno, CA
ABSTRACT
Introduction
Pathogen positive results can put food producers at significant regulatory, legal, and/or political risk. As a result, many avoid pathogen testing altogether or only do the minimum required by regulation or customer requirement. Some supplement with risk indicator methods that do not give a pathogen result but are specific for targets that include pathogens and non-pathogenic bacteria. Unfortunately, only a few risk assessment tools are currently available commercially. Eurofins GeneScan (Eurofins Gold Standard Diagnostics) has recently developed a new tool named Enteric Pathogen Risk Indicator (EPRITM). This real time PCR assay detects common gene targets associated with enteric pathogens along with some closely related non-pathogenic enteric bacteria. Importantly, EPRI presumptives can be tested directly using a fully validated pathogen specific method if desired.
Purpose
To demonstrate proof of concept of the EPRI tool with real-world samples by comparing against a validated pathogen method and culture.
Methods
Contaminated samples (Baby leafy greens, n = 12) were weighed (375 G) and enriched (1:5 ratio mTSB, 20h @ 41.5ºC). Following incubation, aliquots were tested by EPRI and BACGene STEC Multiplex real time PCR methods, and FDA BAM STEC cultural procedures.
Results
One of twelve samples was presumptive for STEC (stx/eae pos) by the STEC Multiplex method. This same sample was presumptive by EPRI. The organism could not be recovered by culture. Results agreed with those obtained by our collaborator who provided the samples.
Significance
The EPRI risk assessment tool was demonstrated to have at least equivalent performance to a pathogen specific method, and could represent a new option for food producers interested in a way to evaluate pathogen risk without testing for pathogens directly. After testing using this tool, producers have the option to test for pathogens from the same enrichment using a validated pathway.
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