New inhibitors for aminoglycoside-adenylyltransferase.

Two hydroxymethyltropolones and two tropolone acetate derivatives were found to inhibit an aminoglycoside-adenylyltranferase in a gentamicin-resistant Escherichia coli strain. The inhibitory effect of tropolones depends on the nature of the aminoglycoside antibiotic subject to adenylation. Combinations of hydroxymethyltropolones with tobramycin were more active compared with tropolone acetates against gentamicin-resistant strains displaying adenylyltransferase activity. On the contrary a combination of the investigated acetate with gentamicin was of lower activity. It could be shown that these inhibitors inhibit, to a varying degree, the transfer of radioactive ATP to different aminoglycoside molecules.