In vitro activity of gemifloxacin against Streptococcus pneumoniae isolates in Germany

The MICs (minimal inhibitory concentrations) of gemifloxacin, moxifloxacin, ofloxacin, ciprofloxacin, levofloxacin, sparfloxacin, penicillin G, tetracycline and erythromycin were determined for 200 clinical pneumococcal isolates using the microbroth dilution method. MIC(50) and MIC(90) values were as follows (mg/l): 0.016 and 0.016 (gemifloxacin, penicillin-intermediate strains), 0.03 and 0.06 (gemifloxacin, penicillin-susceptible strains); 0.125-0.5 and 0.25 (moxifloxcacin); 1-2 and 4 (ciprofloxacin and ofloxacin); 1 and 2 (levofloxacin), and 0.25-0.5 and 0.5 (sparfloxacin). MIC(50) and MIC(90) values for the fluoroquinolones were nearly identical for individual antimicrobial agents in the penicillin-susceptible and penicillin-intermediate groups of strains. Erythromycin and tetracycline were less active against penicillin-intermediate pneumococci isolates (erythromycin: MIC(90) 8 mg/l; MIC range 0.06-> or =64 mg/l; tetracycline: MIC(90) > or =64 mg/l, MIC range 0.25- > or =64 mg/l) as compared to penicillin-susceptible isolates (erythromycin: MIC(90) 0.5 mg/l, MIC range 0.06-> or =64 mg/l; tetracycline: MIC(90) 8 mg/l, MIC range 0.06-> or =64 mg/l).