In vitro evaluation of a semisynthetic derivative of gentamicin B (Sch 21420)

The activities of Sch 21420 and amikacin were compared in vitro against 448 clinical bacterial isolates and against 82 gentamicin-resistant isolates of gram-negative bacilli. At 1 mug/ml, Sch 21420 was more active than amikacin against most Enterobacteriaceae but less active against Pseudomonas aeruginosa. Activity of these antibiotics against gentamicin-resistant organisms varied according to the species examined.