Abstract
Studies concerning the effects of procedural variations on the activity of aminoglycosides have revealed that a single procedural change can significantly alter results, particularly in tests with Staphylococcus aureus (116,123). Variations in such factors as inoculum and type of medium used may at times also alter the clinical interpretation of results, and significant discrepancies between the minimal inhibitory concentrations and minimal bactericidal concentrations of aminoglycosides have been observed (62,90,116). These observations suggest the presence of a small subpopulation of cells within the sensitive parent strain which are more resistant to the effects of the aminoglycoside. Therefore, the purpose of this study was to (a) evaluate the bactericidal activity of aminoglycosides against Staphylococcus aureus by the use of kill curves (b) characterize the more resistant cells selected from strains of Staphylococcus aureus which appeared to be sensitive to aminoglycosides by minimal inhibitory concentration determinations, and (c) determine the prevalence of strains containing these more resistant cells.