Effect of acid-adaptation on Listeria monocytogenes survival and translocation in a murine intragastric infection model

Acid tolerance response mechanisms can greatly influence Listeria monocytogenes survival in low pH foods. In the present paper, the effect of acid-adaptation together with control of gastric pH level on L. monocytogenes survival and translocation was analyzed after intragastric inoculation in the BALB/c mouse model. Our results showed that acid-adaptation led to an increase in resistance to the first barrier constituted by the low gastric pH and that inoculation at alkaline pH had a synergistic effect. It resulted in a higher live bacterial load reaching the next intestinal compartments and was correlated with increased translocation rates to the mesenteric lymph nodes, both at the frequency and quantitative levels. Our results in this murine model suggest that acid-adaptation of L. monocytogenes in low pH foods, together with control of gastric pH level through dietary practices, or use of inhibitors of gastric acid secretion, may be potential aggravating risk factors to food-borne listeriosis. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.