Certain dietary carbohydrates promote Listeria infection in a guinea pig model, while others prevent it

It has been proposed that dietary non-digestible carbohydrates can improve host resistance to intestinal infections by stimulating health-promoting bacteria in the gut. However, evidence from in vivo infection studies is scarce, particularly for gram-positive infections. We studied the effect of five non-digestible carbohydrates on the resistance of guinea pigs to Listeria monocytogenes infections. Animals were fed a diet supplemented with 10% xylooligosaccharides (XOS), galactooligosaccharides (GOS), inulin, apple pectin or polydextrose for three weeks before oral infection with a mixture of three different fluorescently labeled L monocytogenes strains. Colonisation of L. monocytogenes in the intestine was determined by quantification of L. monocytogenes in faecal, ileal and caecal samples while translocation was determined by quantification of L monocytogenes in mesenteric lymph nodes, spleen and liver. XOS and GOS significantly (P<0.05) improved the resistance of guinea pigs to L monocytogenes, while inulin and apple pectin decreased the resistance (P<0.05). No significant effect on resistance to L. monocytogenes was seen after feeding with polydextrose. No difference in caecal weight or pH between the dietary groups was measured, except for a higher caecal weight and a lower caecal pH of animals fed with XOS, and a lower caecal pH for animals fed with polydextrose. In conclusion, this study shows for the first time that different non-digestible carbohydrates can have entirely different effects on the intestinal colonisation and translocation of a pathogenic bacterium. (C) 2010 Elsevier B.V. All rights reserved.