Interlaboratory validation of a multiplex qPCR method for the detection of Listeria monocytogenes in a ready-to-eat seafood product

Listeria monocytogenes is a major foodborne pathogen which mainly infects susceptible individuals through the consumption of contaminated foods. To this end, ready-to-eat (RTE) food products are of particular concern as this microorganism is widely distributed, can survive, and even grow, under adverse conditions, and thus must be carefully controlled. In the present study, an interlaboratory ring trial was organized to evaluate an open formula qPCR-based method for the detection of L. monocytogenes. The molecular method was evaluated on a novel RTE seafood product, developed in the framework of a European project, the SEAFOODAGE (EAPA_758/2018). Six laboratories located in Spain and Portugal participated in the study, and the results obtained indicated that this new method presented high diagnostic sensitivity (100%) reaching a low limit of detection (<10 CFU/25 g) with an overall agreement with the reference method, attending to the Cohen's k, of 0.97 that is interpreted as “almost complete agreement”.