The ability of enteric diarrhoeal pathogens to ferment starch to short-chain fatty acids in vitro

Background: Short-chain fatty acids (SCFA), produced ill the normal colon by bacterial fermentation, are decreased in acute diarrhoea. This mag-have deleterious effects on epithelial function in the colon. Methods: The ability of several diarrhoeal pathogens to produce SCFA when incubated with starch in vitro was studied. Isolated pathogens were incubated for 24 h with either no added substrate, glucose, or starch under anaerobic conditions, and SFCA were quantitated by gas-liquid chromatography. Results: Unlike the normal colonic flora, the pathogens produced acetate but not propionate or butyrate. D-lactate was also produced by all the pathogens studied, When the pathogens were incubated in anaerobic medium containing starch, significantly; greater amounts of acetate and significantly lesser amounts of lactate were produced. Conclusions: The inability of enteric pathogens to produce butyrate may impair epithelial cell function, whereas production of D-lactate may enhance mucosal damage in diarrhoeal disease. The presence of luminal starch may be helpful in shifting the fermentation profile to a more favourable pattern.