Selection of resistant subpopulations after in vitro exposure to gentamicin, tobramycin and amikacin in clinical isolates of Enterobacteriaceae

Abstract

In an attempt to select subpopulations of aminoglycoside resistant strains, 108 isolates of Enterobacteriaceae were subjected to serial passages in the presence of increasing concentrations of these agents. Agar plates containing gentamicin (GM), tobramycin (TM) and amikacin (AMK) were employed. We found that only 30 strains exhibited an increase in the minimal inhibitory concentrations (MICs) of all aminoglycosides tested resulting in resistance to these antibiotics.