Detection and differentiation of Listeria spp. by a single reaction based on multiplex PCR

The lap gene encodes the protein p60, which is common to all Listeria speci es. A previous comparison of the DNA sequences indicated conserved and spec ies-specific gene portions. Based on these comparisons, a combination consi sting of only five different primers that allows the specific detection and differentiation of Listeria species with a single multiplex FCR and subseq uent gel analysis was selected. One primer was derived from the conserved 3 ' end and is specific for all Listeria species; the other four primers are specific for Listeria monocytogenes, L. innocua, L. grayi, or the three gro uped species L. ivanovii, L. seeligeri, and L, welshimeri, respectively. Th e PCR method, which also enables the simultaneous detection of L. monocytog enes and L. innocua, was evaluated against conventional biotyping with 200 food hygiene-relevant Listeria strains. The results indicated the superiori ty of this technique. Thus, this novel type of multiplex PCR may be useful for rapid Listeria species confirmation and for identification of Listeria species for strains isolated from different sources.