In vitro activity of fleroxacin and 14 other antimicrobials against slime- and non-slime-producing Staphylococcus epidermidis.

The in vitro activity of the 4-quinolone compound fleroxacin (Ro-23-6240) was compared with that of 14 other antimicrobials against a total of 50 recent clinical isolates of 25 slime- and 25 non-slime-producing coagulase-negative staphylococci. Susceptibility testing (MIC/MBC) was performed by a microtiter broth dilution technique and the combination effect of fleroxacin plus rifampin was studied by checkerboard titration in microtiter trays. Fleroxacin inhibited the most slime- and non-slime producing coagulase-negative staphylococci at MIC90 0.25 and I micrograms/ml, respectively. Overall fleroxacin was as active or even better as ofloxacin, cefotiam, cefazolin, cefamandole, clindamycin or vancomycin but 2- to 8-fold less active than rifampin. The fleroxacin-rifampin combination was indifferent in 17%, additive in 78.7% and synergistic in 4.3%.