Background/aims: Our goal was to demonstrate the role of bacteria in altered bile acid metabolism, which overgrow in the upper small intestine of patients with progressive systemic sclerosis. We identified the bacterial species, isolated from the jejunal fluid obtained from patients with progressive systemic sclerosis, who had previously shown an increase in 14CO2, specific activity on breath test, and normal controls. After which, we investigated the deconjugation ability of the isolated bacteria and the relationship between 14CO2, specific activity and gastric pH.
Methodology: Bile acid breath tests were performed on 12 patients, and 19 normal controls using 5 microCi of oral glycine-1-(14)C-labeled glycocholate. Jejunal fluid was aspirated through a double lumen-tube with a rubber cover on the tip. Deconjugation ability was examined by thin-layer chromatography using conjugated bile acids in ox gall.
Results: The following species were identified in jejunal fluid samples obtained from patients: Bacteroides vulgatus, Eubacterium lentum, enterococcus, Lactobacillus bifidus, Escherichia (E) coli, Aerobacter (A) aerogenes. Except for E. coli and A. aerogenes, these species were capable of hydrolyzing conjugated bile acids in ox gall. The administration of chloramphenicol (1 g orally per day for 14 days in divided doses) significantly reduced the 14CO2, specific activity (p<0.05) in the patients with progressive systemic sclerosis. On the other hand, nineteen healthy control subjects demonstrated no increase in CO2 excretion, and 16 of the 19 had no bacteria isolated from jejunal fluid. The remaining healthy man showed an overgrowth of E. coli and Pseudomonas (P) aeruginosa, but the E. coli and P. aeruginosa did not have the ability of deconjugation. CO2 specific activity of expired breath samples in the patients with progressive systemic sclerosis was correlated with gastric pH (n=12, r=0.588, p<0.05).
Conclusions: Our results demonstrated that some of the bacterial species that overgrow in the upper small intestine of patients with progressive systemic sclerosis can deconjugate bile acids, and that a shift to neutral pH in gastric juice, may promote the bacterial overgrowth related to their impaired peristaltic activity.