Activity of 5-episisomicin compared with that of other aminoglycosides

5-Episisomicin, a semisynthetic aminoglycoside, has been shown to inhibit many members of the Enterobacteriaceae, Pseudomonas aeruginosa, and Staphylococcus aureus. At a concentration of 3.1 mug/ml, more than 90% of Escherichia coli, Klebsiella pneumoniae, Enterobacter, Citrobacter, indole-positive Proteus, and Providencia were inhibited. 5-Episisomicin had activity against S. aureus, E. coli, Klebsiella, Enterobacter, and Citrobacter similar to gentamicin and netilmicin. It had activity similar to amikacin and netilmicin against many gentamicin-resistant bacteria. The activity of 5-episisomicin was greatest at an alkaline pH and in medium of low magnesium content. Synergy of 5-episisomicin and carbenicillin was found to occur most often against Pseudomonas.