Effect of Antibiotics on Bile Acid Composition of Bile

Abstract

The bile acid composition of human, rat and hamster bile was determined before andafter administration of antibiotics. A mixture of tetracycline and oleandomycin, oleandomycinstreptomycin or chloramphenicol was administered orally, intraperitoneally or intramuscularly.Bile acids were extracted with chloroform/methanol 1: 1 and analysed by combination ofTLC-GLC and TLC-colorimetric procedures. The ratio of glycine to taurine conjugates (G/T ratio) and the ratio of deoxycholate to chenodeoxycholate (DC/CDC ratio) weredetermined.
Both G/T and DC/CDC ratios showed a very wide range of individual variations inhuman bile. After oral administration of antibiotics, these ratios were decreased and therange of variation was makedly reduced.
In rat bile glycine conjugates almost completely disappeared after oral administrationor injection of antibiotics. The decrease of G/T ratio was shown by oral administrationof non-absorbable antibiotics almost to the same extent as absorbable ones.
G/T ratio was also decreased in hamster bile after the antibiotic treatment. DC/CDCratio was decreased by oral administration of antibiotics, but it was not decreased when theantibiotics were given by injection.
The oral administration of a mixture of tetracycline and oleandomycin caused an unusualincrease in ursodeoxycholate in humans, and an increase in unidentified bile acid componentin rats.
The use of antibiotics seems to give an influence on the balance of glycine and taurineconjugates through their effects on the bacterial flora in intestinal lumen as well as throughthe direct effect on the conjugation system in liver.