Influence of Antibiotics on the Faecal Excretion of Bile Pigments in Healthy Subjects

We have evaluated the effects of 10 antibiotics, given orally for 6 days to healthy subjects, on faecal excretion of urobilinogen. Intake of bacitracin, vancomycin, clindamycin, erythromycin, and ampicillin resulted in a pronounced suppression of the faecal excretion of urobilinogen (p < 0.05). Intake of doxycycline, metronidazole, nalidixic acid, ofloxacin, and trimethoprim/sulphamethoxazole had no significant effect. The effects of three antibiotics–ampicillin, clindamycin, and metronidazole– on faecal excretion of conjugated bilirubin were similarly evaluated. Intake of clindamycin led to a marked increase of conjugated bilirubin (p < 0.05) in the faeces, and the pattern of separated azopigment derivatives of the bilirubin conjugates became altered. Intake of ampicillin and metronidazole resulted in far less alterations in faecal conjugated bilirubin, although a significant change was observed in the subjects receiving metronidazole (p < 0.05). The differences between the antibiotics with regard to alt...