In vitro and in vivo activities of sparfloxacin and reference drugs againstChlamydia pneumoniae

The activities of sparfloxacin and reference drugs againstChlamydia pneumoniae were compared by using in vitro and in vivo methods. The minimum inhibitory concentration (MIC) (μg/ml) ranges of sparfloxacin, levofloxacin, tosufloxacin, grepafloxacin, AM-1155, DU-6859a, clarithromycin, azithromycin, and minocycline for sixC. pneumoniae strains (two standard and four clinical strains) were 0.031 to 0.063, 0.25 to 0.5, 0.063 to 0.125, 0.063 to 0.125, 0.063 to 0.125, 0.031 to 0.063, 0.016 to 0.031, 0.125 to 0.25, and 0.016 to 0.031, respectively. The in vitro potency of sparfloxacin againstC. pneumoniae was similar to that of clarithromycin, minocycline, and DU-6859a, and higher than that of the other fluoroquinolones and azithromycin. Fatal pneumonia was induced in cyclophosphamide-treated leukopenic mice by intranasal inoculation withC. pneumoniae KKpn-2. Infiltration of the lung by neutrophils and lymphocytes was confirmed by histopathologic examination. Oral treatment with the various antichlamydial agents was given for seven days; sparfloxacin and minocycline had the lowest ED₅₀ (effective treatment dose in 50% of the mice; given as mg/kg per dose) (1.11 each), followed by DU-6859a (1.92), tosufloxacin (2.09), grepafloxacin (2.41), clarithromycin and azithromycin (2.48 each), AM-1155 (2.77), and levofloxacin (>10). These results suggest that sparfloxacin may be an effective agent forC. pneumoniae infection in humans.