Description:
<jats:p>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<sub>50</sub> and MIC<sub>90</sub> 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<sub>50</sub> and MIC<sub>90</sub> 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<sub>90</sub> 8 mg/l; MIC range 0.06–≧64 mg/l; tetracycline: MIC<sub>90</sub> ≧64 mg/l, MIC range 0.25– ≧64 mg/l) as compared to penicillin-susceptible isolates (erythromycin: MIC<sub>90</sub> 0.5 mg/l, MIC range 0.06–≧64 mg/l; tetracycline: MIC<sub>90</sub> 8 mg/l, MIC range 0.06–≧64 mg/l).</jats:p>