Antibacterial active components in human urine after administration of penicillins

Four-hourly urine from volunteers and patients who had received penicillins orally or intravenously was investigated by means of thin layer chromatography and bioautography. Antibacterially active metabolites were not detected with only two of 12 penicillins, namely amoxicillin and mezlocillin. In the case of the other penicillins the metabolites possessed variable antibacterial activity as could be demonstrated using different test microorganisms. After administration of carbenicillin esters three antibacterially active spots were detected, one of which corresponded to penicillin G; the other two were active against Pseudomonas aeruginosa. The bioautogram after treatment with azlocillin showed two components which were active against Bacillus subtilis, Staphylococcus aureus and Escherichia coli; only the rapid moving component was active against P. aeruginosa, however. The formation and chemical nature of these additional active components is still to a large extent not understood. It is quite possible, however, that they affect the bio-availability of an antibiotic.