Gentamicin-Adenylyltransferase Activity as a Cause of Gentamicin Resistance in Clinical Isolates of Pseudomonas aeruginosa

Abstract

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 .