Validation of the Applied Food Diagnostics, Inc. Simultaneous Multiplex Real Time PCR (SIMUL-qPCR) Listeria Species and Monocytogenes Assay in Selected Foods and Environmental Surfaces: AOAC Performance Tested MethodSM 062001.

Abstract

The Simultaneous Multiplex Real Time PCR (SIMUL-qPCR) Listeria species and monocytogenes Assay is a quick, reliable method for detecting Listeria species and monocytogenes in environmental and food samples. The assay multiplexes several targets in one run to properly identify Listeria species and monocytogenes. The assay uses proprietary medium, Listeria Recovery and Enrichment Broth (LREB), for enrichment purposes. LREB was specifically formulated to improve the recovery and growth of Listeria while inhibiting competing background flora. This report details the method validation study to validate frankfurters, ready-to-eat (RTE) sliced turkey, soft fresh raw cheese, chicken salad, ice cream, cooked eggs, pasteurized milk, and frozen/cooked shrimp, as well as environmental surface sponges and swabs for stainless steel, plastic, rubber, ceramic tile, and sealed concrete. Matrix studies, inclusivity/exclusivity, product consistency/stability, and robustness testing were conducted to assess the method's performance. There were no statistically significant differences found between the candidate and reference methods in the matrix studies. Inclusivity/exclusivity testing showed that the assay was able to detect both Listeria species and monocytogenes strains while excluding the non-Listeria isolates. Small variations in critical test parameters (enrichment time, extraction reagent volume, and extracted sample volume) did not adversely affect the assay's performance, and stability testing indicated consistent results for at least 1 year. The data presented in this report show that this a reliable method for detecting Listeria species and monocytogenes. This assay allows for one sample to be tested for both Listeria species and monocytogenes with one PCR test.