Journal of Antimicrobial Chemotherapy (1999) 43, Suppl. C, 77-82
© 1999 The British Society for Antimicrobial Chemotherapy
Pharmacodynamics of levofloxacin and ofloxacin against Streptococcus pneumoniae
Max. Von Pettenkofer-Institut, Pettenkoferstrasse 9a, D-80336 München, Germany
The aim of this study was to compare the bactericidal efficacy of levofloxacin and ofloxacin against Streptococcus pneumoniae at different dosage regimens for both agents. An in-vitro pharmacodynamic model was used. Levofloxacin kinetics of 500 mg, administered od or bd, were compared with ofloxacin kinetics of 400 mg od or bd. Killing by 3 log 10 (99.9%) was achieved up to an MIC of 0.5 mg/L (500 mg od) or 1 mg/L (500 mg bd). For levofloxacin killing of S. pneumoniae was unimpaired in mixed cultures with Haemophilus influenzae. For ofloxacin, killing by 2 log 10 was achieved up to an MIC of 0.5 mg/L for 400 mg od and up to an MIC of 1 mg/L for 400 mg bd. Killing by 3 log 10 was not achievable by 400 mg od, but was achieved up to an MIC of 0.5 mg/L for 400 mg bd. Killing of S. pneumoniae with identical MICs of levofloxacin was not influenced by their susceptibility to penicillin G. These data, together with the two-fold higher activity of levofloxacin in comparison with ofloxacin, indicate good therapeutic perspectives for levofloxacin over ofloxacin in the treatment of S. pneumoniae infections.
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