Effect of Bacteroides melaninogenicus culture supernatant and deconjugated bile salt on lipid absorption.

Lipid malabsorption is a common clinical manifestation of small bowel bacterial overgrowth. Its pathogenesis, however, remains controversial. Bacteroides melaninogenicus ssp. intermedius, an anaerobic bacterium, is commonly isolated from the upper bowel of patients with small intestinal bacterial overgrowth. The effects of a culture supernate of this organism and deoxycholate, an unconjugated bile salt, on intestinal oleic acid absorption were examined using a rat closed-loop model. The supernatant reduced the in vitro uptake of oleic acid by 19% (P< 0.001). Deoxycholate did not significantly reduce the lipid absorption. Combined supernate and deoxycholate did not have an additive effect on absorption of oleic acid. We conclude that anaerobic bacterial products may contribute to the malabsorption of lipid in the setting of bacterial overgrowth of the small bowel.