3-0-demethyl fortimicin A: In vitro activity and interpretive zone standards for disk diffusion susceptibility tests

Publisher Website
Google Scholar
Abstract
The in vitro activity of 3-0-demethyl fortimicin A was compared to that of amikacin and tobramycin against 5,230 clinical isolates in four institutions. Amikacin and tobramycin were more active than 3-0-demethyl fortimicin A againstPseudomonas aeruginosa andAcinetobacter spp., but all three drugs had similar activity against theEnterobacteriaceae andStaphylococcus aureus. Additional tests with 335 representative gram-negative bacilli compared five different aminoglycosides, demonstrating differences with some isolates. Standardized disk diffusion tests were also performed with 30μg 3-0-demethyl fortimicin A disks, according to the National Committee for Clinical Laboratory Standards. The following interpretive breakpoints are proposed: ⩽ 11 mm for resistant (MIC ⩾32μg/ml) and ⩾ 15 mm for susceptible (MIC ⩽ 16μg/ml).