Purpose: This study aimed to evaluate the 3M Molecular Detection Assay 2 Listeria monocytogenes (3M MDA 2 Listeria monocytogenes) in comparison to the conventional ISO 11290-1 method.
Methods: Sixty 25-gram chicken meat samples and 60 environmental samples (sponge sticks) were collected from chicken processing plants. Additionally (n=49) chicken meat and (n=50) sponge with letheen broth samples were artificially inoculated with Listeria monocytogenes using 200, 20, 2, 0.2, and 0.02 CFU/sample to determine the each method’s sensitivity. Duplicate sets of each sample were screened for Listeria monocytogenes using ISO 11290-1 and 3M MDA 2 Listeria monocytogenes. PCR targeting the genus specific prsA and species specific hly genes and sequencing were used on presumptives to confirm genus and species.
Results: Of the 120 naturally contaminated samples, 6 and 7 samples were positive for Listeria monocytogenes by ISO 11290-1 and 3M MDA 2 Listeria monocytogenes, respectively. Of the 109 chicken meat samples, 3M MDA 2 Listeria monocytogenes detected Listeria monocytogenes with 96.33% relative accuracy, 98.85% relative specificity, and 86.36% relative sensitivity on naturally and artificially contaminated samples. In the 110 sponge samples, relative accuracy, specificity, and sensitivity were 97.27%, 96.97%, and 100%, respectively. The detection limit was < 2 CFU.
Significance: This study demonstrates that compared to ISO 11290-1, the 3M MDA 2 Listeria monocytogenes is reliable and accurate and at the same time this rapid molecular detection assay offers a faster time to result in the detection of Listeria monocytogenes in food processing.