LISTERIA MONOCYTOGENES IN OVINE SAUSAGE: MOLECULAR CHARACTERIZATION AND ANTIMICROBIAL SUSCEPTIBILITY OF ISOLATES

In this study, we monitored the different stages of ovine sausage production for detecting the presence of Listeria monocytogenes in food matrices, the equipment and the environment. A total of 32 isolates were characterized using serotyping and PFGE. Five virulence genes (actA, hlyA, plcB, prfA, iap) were detected by PCR. In this study, furthermore, we determined the susceptibility of L. monocytogenes isolates to 20 antimicrobial agents using Sensititre plates. All isolates were resistant to oxacillin and tigecycline, but susceptible to the other antibiotics. All isolates resulted PCR-positive for the investigated virulence genes. PFGE identified two different pulsotypes. Five isolates, marked as type A and belonging to the serotype 1/2a, were isolated just from one batch samples whereas the type B (n=28), belonging to the serotype 1/2b, was isolated from five different food batches and from the floor drain.