Fortimicins C, D and KE, new aminoglycoside antibiotics

From the fermentation broth of Micromonospora olivoasterospora CS-26 that produced fortimicins A and B three new aminoglycoside antibiotics, fortimicins C, D and KE, were isolated. Fortimicins C and D exhibited potent, broad spectrum antibacterial activities against Gram-positive and negative bacteria, while fortimicin KE was only weakly active.