In vitro activity of gemifloxacin compared with other antimicrobial agentsagainst recent clinical isolates of streptococci

This study investigated the in vitro activity of gemifloxacin (SB-265805) a gainst 50 recent clinical isolates of Streptococcus pyogenes, Streptococcus agalactiae and viridans streptococci using the microdilution method. This activity was compared with that of the quinolone agents ofloxacin, ciproflo xacin, levofloxacin, trovafloxacin and grepafloxacin, and with that of peni cillin, ampicillin, clarithromycin and azithromycin. Gemifloxacin was signi ficantly more potent than the other quinolones tested. Its potency was equa l to that of penicillin for S. agalactiae, and superior to that of penicill in for viridans streptococci. The MIC50 of gemifloxacin for S. pyogenes (0. 015 mg/L) was equal to that of penicillin, with an MIC90 of 0.03 mg/L, Gemi floxacin was also active against isolates of S, agalactiae (MIC = 0.03-0.06 mg/L) and S. pyogenes (MIC = 0.03-0.06 mg/L) with reduced susceptibility t o ofloxacin (MIC = 4-8 mg/L) and grepafloxacin (MIC = 4 mg/L), These prelim inary observations indicate that gemifloxacin is a promising antimicrobial agent for clinical use.