Comparison of Roka Atlas® System Performance and Health Canada Reference Method for Listeria Detection From Plastic, Sealed Concrete, and Stainless-Steel Surface Samples.

Abstract

There is a high demand in the food industry and in public health for rapid automated methods capable of high-volume sample processing. In an unpaired study, Roka Atlas® System performance was compared with Health Canada reference method MFHPB-30 for Listeria spp. (LSP Roka assay) and Listeria monocytogenes (LmG2 Roka Assay) detection on plastic (PL), sealed concrete (SC), and stainless-steel (SS) surfaces (45 samples each per candidate or reference method). Seeking shorter enrichment time for the candidate method, R2 medium pre-enrichment for 14, 16, and 24 h at 35°C was combined with the Roka assay. Listeria welshimeri, L. innocua, and L. monocytogenes were employed to individually inoculate each of the three surfaces, with two competing microorganisms within the 10-100-fold higher concentration range. False negative, false positive, sensitivity, and specificity were 0, 0, 100, and 100%, respectively, for the plastic, sealed concrete, and stainless-steel surfaces, regardless of inoculation level (high, low, and uninoculated) and enrichment time. Candidate method detected 10, 7, and 9 true positives, versus 10, 6, and 10 by the reference method in individually inoculated SS, PL, and SC, respectively. Probability of detection for all the three surfaces for the Roka Atlas System was comparable to the reference method in this unpaired study. The Roka Atlas System detected targets after as little as 14 h enrichment. Surface type did not negatively affect assay sensitivity or specificity. The Roka Atlas System was comparable to the reference method.