SVILUPPO DI UNA PCR MULTIPLEX PER L’IDENTIFICAZIONE E SIEROTIPIZZAZIONE DI L. MONOCYTOGENES ISOLATA IN CASEIFICI OVINI

A new multiplex PCR for identification and serotyping of L. monocytogenes (L.m.) was developed and tested on reference strains of L.m.(5), L. innocua, L. welshimeri, L. seeligeri, and L. ivanovii. PCR primers were designed as previously described from iap gene fragment for identification and variable regions of the L.m. genome for serotyping in order to classify the strains into five groups [1/2a(3a), 1/2b, 1/2c(3c), 4b(d,e), and 4a/c]. The multiplex PCR reproducibility was also tested on 28 strains isolated from sheep’s cheese-processing plants. The results of the PCR multiplex agreed with those of the conventional identification and serotyping agglutination methods. The strains isolated from sheep’s dairy plant belonged to 1/2a (17), 4b (8), and 1/2b (3) serotypes.