In vitro antibacterial activity of kasugamycin

Kasugamycin is an aminoglycosidic antibiotic which was initially reported as being of potential use against Pseudomonas. Our evaluation of this antibiotic does not confirm this expectation. The median minimal inhibitory concentration (MIC) of the Pseudomonas strains tested was 250 mug/ml and the bactericidal level was 500 mug/ml. Kasugamycin was found to be slightly more active in a more basic medium (Mycin Assay broth) in which the median MIC for 11 Pseudomonas strains was 125 mug/ml. Kasugamycin manifests a modest degree of serum binding. Kasugamycin did not have any appreciable effect against a variety of bacteria tested. The only exceptions were several species of gram-negative bacteria, against which more satisfactory antibiotics already exist. Further evaluation of kasugamycin for potential human use as an antipseudomonal agent does not appear warranted.