In vitro and in vivo efficacies of T-3811ME (BMS-284756) against Mycoplasma pneumoniae

T-3811, the free base of T-3811ME (BMS-284756), a new des-F(6)-quinolone, s howed a potent in vitro activity (MIC at which 90% of the isolates tested a re inhibited [MIC90], 0.0313 mug/ml) against Mycoplasma pneumoniae. The MIC 90 of T-3811 was 4-fold higher than that of clarithromycin but was 4- to 8 fold lower than those of trovafloxacin, gatifloxacin, gemifloxacin, and mox ifloxacin and was 16- to 32-fold lower than those of levofloxacin, ciproflo xacin, and minocycline. In an experimental M. pneumoniae pneumonia model in hamsters, after the administration of T-3811ME (20 mg/kg of body weight as T-3811, once daily orally) for 5 days, the reduction of viable cells of M. pneumoniae in bronchoalveolar lavage fluid was greater than those of trova floxacin, levofloxacin, and clarithromycin (20 and 40 mg/kg, orally) (P < 0 .05).