The fecal microflora and bile acids in children with cystic fibrosis

Abstract

Fecal fat, bile acids,and the rectal microflora were studied in seven control children and in three groups of patients with cystic fibrosis (CF), seven were off antibiotics, ten on oral cloxacillin, and six on iv. triple therapy (cloxacillin, gentamycin, and carbenicillin) for at least 2 weeks. Controls had lower concentrations (milligrams per gram dry stool) of both fat (P < 0.005) and bile acids (P < 0.025) than CF children off antibiotics. Antibiotics had little or no effect on fat but led to a striking decrease (P < 0.01) of bile acids in the triple therapy group. Concomitantly, there was reduced deconjugation of bile acids (P < 0.01) and formation of secondary bile acids (P <0.005). This was associated with a 5-fold increase in the percentage of bile acids found in the aqueous phase of stools and with a marked reduction (P < 0.001) of the anaerobic flora (log counts per gram wet stool) in children on triple therapy (4.3 ± 1.9) when compared to controls (9.8 ± 0.1), CF off antibiotics (9.1 ± 0.1) and CF on cloxacillin (9.6 ± 0.2). The close relationship between the anaerobic flora, the extent of bile acid microbial transformation, and fecal bile acid concentrations suggest that reduction of the anaerobic flora decreases adsorption of bile acids to dietary residues and microbes, favors bile acid absorption, and leads to a decreased fecal loss of bile acids in CF. Am. J. Clin. Nutr. 32: 2404-2409, 1979.