<i>In vitro</i> Assessment of Tobramycin, a new Aminoglycoside with Anti-<i>Pseudomonas</i> Activity

Abstract

In vitro studies of tobramycin showed it to be 2- to 4-fold more active than gentamicin against Pseudomonas species. 55 of 56 strains were inhibited by 2.5 μg of tobramycin/ml. Other gram-negative bacteria showed variable susceptibility to the drug. Strains of Staphylococcus aureus were generally inhibited by, and enterococci were generally resistant to 5 μg of tobramycin/ml. The effect of serum and of NaCl in the medium were studied. Combinations of tobramycin with carbenicillin gave conflicting results when examined for synergism against Pseudomonas by two different methods. Tobramycin failed to show synergism with penicillin against enterococci.