Survival of clinical and food isolates of listeria monocytogenes through simulated gastrointestinal tract conditions

Twenty-seven strains of Listeria monocytogenes previously isolated from food (n¼16) and human patients of listeriosis (n¼11) were characterized and compared based on their ability to survive through the simulated gastrointestinal tract conditions. Cells were exposed (60 or 120 min) to low pH in the presence of pepsin, to simulate the digestion in the stomach, and subsequently to bile salts to simulate the digestion in the small intestine (60 or 120 min). Their survival was shown to be origin- (food and clinical) and strain dependent ( p<0.001) and also significantly dependent on the imposed simulated gastric conditions (long vs. quick exposure) ( p