Purpose: Compare the detection and assay efficiency of Listeria species in environmental samples after 24-28 hour enrichment with the Roka Listeria Detection Assay on Atlas™ System, DuPont Qualicon’s BAX® System PCR 24E Assay, and bioMérieux VIDAS® LSX.
Methods: Divide environmental sponges (n=130) into 3 subsamples for parallel analysis as follows: add 30mL Butterfields, transfer 10mL to 3 enrichment bags, perform assay, and compare to culture. For the Roka assay, enrich 24-28 hours in Half-Fraser at 35°C, transfer sample to a collection tube containing lysis reagent, and test on the Atlas System. For the BAX assay, enrich 24-28 hours in 24 LEB at 37°C, transfer sample to cluster tubes for two part lysis procedure, hydrate PCR tablet with lysate, and test on BAX. For the VIDAS assay, enrich 24-26 hours in LX at 30°C, transfer sample to a tube for high temperature lysis procedure, transfer a volume of lysate to LSX strips, and test on VIDAS®. Post enrichment enumeration on MOX agar is determined with discrepant analysis on MOX agar after 48 hour enrichment in Fraser media.
Results: The Roka and VIDAS assays demonstrate 100% sensitivity and specificity, and the BAX assay demonstrates 94.4% sensitivity and 97.4% specificity. Additionally, Roka’s method had a higher detection rate than BAX or VIDAS.
Significance: The Roka and VIDAS assays demonstrate improved sensitivity and specificity compared to BAX. However, Roka’s method provides a higher detection rate of Listeria compared to VIDAS.