RT Journal Article
SR Electronic
T1 Increasing the intestinal resistance of rats to the invasive pathogen Salmonella enteritidis: additive effects of dietary lactulose and calcium.
JF Gut
JO Gut
FD BMJ Publishing Group Ltd and British Society of Gastroenterology
SP 497
OP 504
DO 10.1136/gut.40.4.497
VO 40
IS 4
A1 I M Bovee-Oudenhoven
A1 D S Termont
A1 P J Heidt
A1 R Van der Meer
YR 1997
UL http://gut.bmj.com/content/40/4/497.abstract
AB BACKGROUND AND AIMS: Lactulose fermentation by the intestinal microflora acidifies the gut contents, resulting in an increased resistance to colonisation by acid sensitive pathogens. The extent of fermentation should be controlled to prevent acid induced epithelial cell damage. Considering the buffering capacity of calcium phosphate and its intestinal cytoprotective effects, whether supplemental calcium phosphate adds to the increased resistance to intestinal infections by lactulose fermentations was studied. METHODS: In a strictly controlled experiment, rats were fed a purified low calcium control diet, a low calcium/lactulose diet, or a high calcium/lactulose diet, and subsequently infected orally with Salmonella enteritidis. RESULTS: Lactulose fermentation lowered the pH and increased the lactic acid concentration of the intestinal contents, which significantly reduced excretion of this pathogen in faeces; thus it improved the resistance to colonisation. This agreed with the high sensitivity of S enteritidis to lactic acid (main metabolite of lactulose fermentation) in vitro. Calcium phosphate decreased translocation of S enteritidis to the systemic circulation, an effect independent of lactulose. The unfavourable increased cytotoxicity of faecal water caused by lactulose fermentation was more than counteracted by supplemental calcium phosphate. Moreover, calcium phosphate stimulated lactulose fermentation, as judged by the reduced lactulose excretion in faeces and increased lactic acid, ammonia, and faecal nitrogen excretion. CONCLUSION: Extra calcium phosphate added to a lactulose diet improves the resistance to colonisation and translocation of S enteritidis. This is probably mediated by a calcium induced stimulation of lactulose fermentation by the intestinal microflora and reversion of the lactulose mediated increased luminal cytotoxicity, which reduces damage inflicted on the intestinal mucosa.