Epidemiologia molecolare, fattori di patogenicità e antibiotico-resistenza diListeria monocytogenesisolata da salsiccia ovina

In this study, we have monitored the different stages of ovine sausage production for detecting the presence of Listeria monocytogenes, Salmonella spp. and Escherichia coli o157:H in food matrices, the equipment and the environment. A total of 56 L. monocytogenes isolates were characterized using serotyping and PFGE. Six virulence genes (actA, hlyA, plcB, prfA, iap and lmo2821) were detected by PCR. In this study, furthermore, we determined the susceptibility of L. monocytogenes isolates to 21 antimicrobial agents using Sensititre plates. All isolates were susceptible to all antimicrobial agents analyzed. All isolates resulted PCR-positive for the investigated virulence genes. PFGE identified two different pulsotypes. Twelve isolates, marked as type A and belonging to the serotype 1/2a, were isolated just from one batch samples whereas the type B (n=44), belonging to the serotype 1/2b, was isolated from five different food batches, from the floor drain and the mixer.