noun A broad-spectrum aminoglycoside antibiotic mixture, derived from an actinomycete (Micromonospora echinospora), extensively used as the sulfate in treating severe systemic bacterial infections (as of the urinary tract); (3R,4R,5R)-2-{[(1S,2S,3R,4S,6R)-4,6-diamino-3-{[(2R,3R,6S)-3-amino-6-[(1R)-1-(methylamino)ethyl]oxan-2-yl]oxy}-2-hydroxycyclohexyl]oxy}-5-methyl-4-(methylamino)oxane-3,5-diol.