Comparative in vitro activity of moxifloxacin against Gram-positive clinical isolates

The in vitro activity of moxifloxacin was compared with that of 15 antibact erial agents against 513 Gram-positive microorganisms. The MIC90 (mg/L) of moxifloxacin was 0.06 for quinolone-susceptible Staphylococcus aureus and S taphylococcus epidermidis, 0.12 for Streptococcus pyogenes and Streptococcu s agalactiae; 0.25 for Streptococcus pneumoniae, Streptococcus mitis, Strep tococcus bovis, Streptococcus anginosus and Actinomyces pyogenes; 0.5 for S treptococcus sanguis and Listeria monocytogenes, 2 for Corynebacterium jeke ium and Bifidobacterium bivius. Over 50% of Enterococcus faecalis, Enteroco ccus faecium, quinolone-resistant staphylococci, Nocardia asteroides and Cl ostridium difficile were susceptible to less than or equal to 2 mg/L moxifl oxacin. Moxifloxacin and trovafloxacin demonstrated comparably high activit y towards Gram-positive cocci; moxifloxacin and clinafloxacin were most act ive against Grampositive bacilli.