Sisomicin is an aminoglycoside antibiotic, isolated from the fermentation broth of a new species of the genus Micromonospora. It is a newer broad-spectrum aminoglycoside most structurally related to gentamicin. Sisomicin is the most predictably active aminoglycoside against gram-positive bacteria. Like most other aminoglycosides, Sisomicin is bactericidal for sensitive clinical isolates. The Minimum Bactericidal Concentrations (MBC) have been found to be equivalent or very close to the Minimum Inhibitory Concentrations (MIC). Like other aminoglycosides, most clinical isolates of Pseudomonas aeruginosa remain susceptible to sisomicin. Resistance to sisomicin may enzymatically or non-enzymatically be mediated. Sisomicin is inactivated by the same enzymes as gentamicin but it is active against many, not all, organisms that resist gentamicin by non-enzymatic mechanisms.
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