Gentamicin and amikacin---an in vitro comparison using 1000 clinical isolates.

The in vitro antimicrobial activities of gentamicin and amikacin against 1000 bacterial isolates from clinical material were compared. The minimum inhibitory concentrations were determined by an agar dilution technique. Both of these aminoglycoside antibiotics had a similar spectrum of activity, being highly active against most species of aerobic Gram negative bacilli. Gentamicin was more active than amikacin against most species of enterobacteria, Haemophilus influenzae and Staphylococcus aureus but amikacin was more active against a proportion of Klebsiella and Providencia isolates. For most isolates, the differences in activity between gentamicin and amikacin were small, however, amikacin achieves higher serum levels. Most resistant isolates in this survey did not influence patient mortality.