Caratterizzazione molecolare diListeria monocytogenesisolata nella Salsiccia Sarda Stagionata e negli impianti di trasformazione

Listeria monocytogenes is a bacteria pathogenic for humans and animals that can cause meningitis, septicemia, abortion and prenatal infection in high risk categories of people. The aim of this study was to characterizeL. monocytogenes(Lm) isolates and to determine antimicrobial susceptibility in Lm andL. innocua(Li). 76 isolates collected from different sausage processing plants in food and environmental samples, were analyzed. The overall prevalence with phenotyping tests was 54% and 46% respectively for Lm and other species. With molecular method (PCR), 47% were confirmed as Lm, while 29% and 24% resulted Li and L. welshimeri repectively. Serotyping showed that 44.4% of Lm isolates belonged to serotype 1/2c, followed by 1/2a (39%) and 4b (17%). The prevalence of virulence genes by multiplex PCR was: inlA 86.1%, inlB 100%, iap 100%, rrn 97.2%, hlyA 98%, prfA 98%, plcA 97.2%, plcB 97.2%, mpl 100%, actA 30.5%. Lm isolates subtyped by pulsed-field gel electrophoresis were grouped into 4 cluster and 28 pulsotypes were identified, revealing a high genetic diversity. The results of the antimicrobial susceptibility showed that Lm isolates were sensitive to antimicrobials used for listeriosis treatment of choice (97.2% ampicillin and 72.2% gentamicin) but resistant to vancomycin (63.8%) and eritromicin (55.5%). This study contribute to know the virulence of Lm isolated from Sardinian sausage and processing plants and the antimicrobial susceptibility of Lm and Li isolates.