Gentamicin and tobramycin--an in vitro comparison using 1400 clinical isolates.

The in vitro antimicrobial activities of tobramycin and gentamicin against 1400 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 and Staphylococcus aureus. Gentamicin was more active than tobramycin against most species of enterobacteria but tobramycin was more active against Pseudomonas aeruginosa and a proportion of Klebsiella isolates. For most isolates, the differences in activity between gentamicin and tobramycin were small.