Antimicrobial activity of moxifloxacin, gatifloxacin and six fluoroquinolones against Streptococcus pneumoniae

The in vitro and pharmacodynamic effects of moxifloxacin and gatifloxacin a gainst Streptococcus pneumoniae were compared with six other fluoroquinolon es. Organisms included penicillin-susceptible (54) and penicillin-non-susce ptible (145) isolates from 1998-1999, Moxifloxacin and clinafloxacin demons trated the greatest in vitro activity, with MIC(90)s of 0.13 mg/L, followed by trovafloxacin, grepafloxacin > gatifloxacin, sparfloxacin > levofloxaci n > ciprofloxacin. There was no difference in fluoroquinolone activity betw een penicillin-susceptible and -non-susceptible strains. Pharmacodynamic an alysis using published pharmacokinetic information indicates that all the a gents tested except ciprofloxacin had an AUC/MIC90 > 30, with moxifloxacin having the greatest free-drug availability.