Gentamicin-adenylyltransferase activity as a cause of gentamicin resistance in clinical isolates of Pseudomonas aeruginosa.

Gentamicin adenylyltransferase activity was found in extracts of clinical isolates of gentamicin-resistant Pseudomonas aeruginosa. Extracts of one of these isolates, P. aeruginosa POW, inactivated gentamicin in the presence of adenosine 5'-triphosphate. Extracts of strain POW catalyzed the binding of radioactivity from [(14)C]adenine adenosine 5'-triphosphate to gentamicin components, tobramycin, sisomicin, kanamycin A and B and, to a variable degree, streptomycin and spectinomycin. The substrate profile with these agents and other aminocyclitols was similar to that obtained with R factor-mediated gentamicin adenylyltransferase found in Enterobacteriaceae. Adenylylating activity was absent in gentamicin-susceptible mutants of strain POW. Adenylylation may be added to acetylation as an enzymatic mechanism responsible for gentamicin resistance among strains of P. aeruginosa.