Selective growth of resistant variants during incubation of Enterobacteriaceae with four aminoglycosides

The selective growth of resistant variants, present at low frequencies, varied with different strains of Enterobacteriaceae and different aminoglycosides. This phenomenon was more pronounced during incubation with amikacin than with gentamicin, netilmicin and tobramycin. Selective growth of the resistant variants resulted in an inoculum effect and an increase in MIC with longer incubation. In-vitro evaluation of this phenomenon may be justified when choosing an aminoglycoside for therapy.