In vitro studies with Win 42122-2: comparison with gentamicin, netilmicin, and amikacin

The in vitro activity of Win 42122-2 against gram-negative clinical isolates was compared in serial twofold broth dilution tests with gentamicin, netilmicin, and amikacin. Against 173 gentamicin-susceptible Enterobacteriaceae, the activity of Win 42122-2 was generally twofold less than those of gentamicin or netilmicin and similar to that of amikacin. Against 60 gentamicin-susceptible nonfermentative gram-negative bacilli, including P. aeruginosa, the activity of Win 42122-2 was four- to eightfold less than that of gentamicin or netilmicin and two- to fourfold less than that of amikacin. Minimal bacterial concentrations for Win 42122-2 were usually similar to minimal inhibitory concentrations. Win 42122-2 was not highly active against gentamicin-resistant bacteria. Win 42122-2 was as active as gentamicin against Mycobacterium tuberculosis but was less active than gentamicin or amikacin against atypical mycobacteria. Win 42122-2 interacted synergistically with penicillin G against enterococci, including strains highly resistant to streptomycin.