P2-98 A Comparative Evaluation of the Veriflow Listeria Species (LS) Method for the Detection of Listeria Species in Select Foods and Environmental Surfaces

Tuesday, August 5, 2014
Exhibit Hall D (Indiana Convention Center)
Erin Crowley, Q Laboratories, Inc., Cincinnati, OH
Patrick Bird, Q Laboratories, Inc., Cincinnati, OH
Benjamin Bastin, Q Laboratories, Inc., Cincinnati, OH
Jonathan Flannery, Q Laboratories, Inc., Cincinnati, OH
M. Joseph Benzinger, Q Laboratories, Inc., Cincinnati, OH
Megan Boyle, Q Laboratories, Inc., Cincinnati, OH
James Agin, Q Laboratories, Inc., Cincinnati, OH
David Goins, Q Laboratories, Inc., Cincinnati, OH
Introduction: The Invisible Sentinel Veriflow Listeria Species (LS) method utilizes a PCR-based detection method coupled with a rapid vertical flow-based assay to rapidly and accurately detect Listeria species in food products and on environmental surfaces in only 24 hours of non-specialized incubation.   The new method eliminates the need for cumbersome sample preparation steps, gel electrophoresis or fluorophore based detection of target amplifications. This new method provides the specificity and sensitivity of PCR-based amplification in a cost-efficient and easy-to-use format.

Purpose: The purpose of this independent evaluation was to compare the new method to the USDA/FSIS-MLG 8.08 for ready-to-eat (RTE) meats and environmental surfaces and to conduct Inclusivity and Exclusivity testing as part of the AOAC Research Institute™ validation process.

Methods: The method comparison analyzed 4 environmental surfaces (stainless steel, ceramic tile, sealed concrete and plastic) and 2 RTE meats (deli turkey (125 g) and hot dogs (25 g)).  Each matrix was inoculated with a different strain of Listeria species.  After sample enrichment and incubation, samples were lysed and the target DNA was amplified.  The amplified DNA was mixed with a proprietary buffer, transferred to a Veriflow cassette and results were obtained within 3 minutes.  Samples were confirmed following procedures outlined in the USDA/FSIS-MLG.  For the inclusivity and exclusivity evaluation, 50 Listeria species isolates and 30 closely related non-Listeria species isolates were evaluated.

Results: A POD statistical analysis indicated no significant differences observed between the new method and the reference method for all matrices. For inclusivity, 50 out of 50 strains of Listeria species were correctly identified.  All 30 exclusivity organisms were correctly excluded.  

Significance: This new method demonstrated high sensitivity and specificity as an easy to use rapid method for the detection of Listeria species in select foods and environmental surfaces.