Phenotypic variations in gentamicin-resistant isolates of Staphylococcus aureus.

Eight clinical isolates of Staphylococcus aureus showing high level resistance to seven aminoglycosides are described. The resistance did not appear to be due to enzyme inactivation. Possible mechanisms of this resistance are discussed. Resistant strains showed phenotypic variations in the form of different colonial morphology and biochemical activity.