A novel real-time PCR-based method for the detection of Listeria monocytogenes in food

Aims: A new real-time PCR-based method was developed for the detection of Listeria monocytogenes in food. Methods and Results: A two-step enrichment involving a 24-h incubation in half-Fraser broth followed by a 6-h subculture in Fraser broth was used, followed by cell lysis and real-time PCR with primers and a TaqMan probe previously developed in our laboratory. When the method was evaluated with 144 naturally contaminated food samples, 44 were detected as positive by the PCR-based method and 42 by the standard method EN ISO 11290-1. With 61 food samples artificially contaminated at a level of 10 degrees CFU per 25 g, 61 and 58 positive samples were detected by the respective methods. Conclusions: The developed real-time PCR-based method facilitated the detection of L. monocytogenes in food on the next day after the sample reception, with a reduction of false-positive results because of dead bacterial cells and false-negative results because of PCR inhibitors. Significance and Impact of the Study: The method can be used for L. monocytogenes detection in food as a faster alternative to current methods.