In vitro and in vivo activities of sparfloxacin (AT-4140) against Mycobacterium tuberculosis

The in vitro and in vivo activities of sparfloxacin (AT-4140) against M. tubercubsis are reported. The MICs of sparfloxacin for 50% and 90% of 18 clinical isolates were, respectively, 0.25 and 0.5 mg/l, one or two dilutions lower than that of ciprofklxacin and ofloxacin. In mice infected intravenously with 0.1 mg M. tuberculosis H37Rv strain, the minimal effective dosage of sparfloxacin, as assessed by survival rate, spleen enlargement and gross lung lesidns, was 12.5 mg/kg. The activities of various regimens were in the following rank order: INH 25 mg/kg = sparfloxacin 50–100 mg/kg > ofloxacin 300 mg/kg > (or =) sparfloxacin 25 mg/kg > spartloxacin 12.5 mg/kg > (or =) ofloxacin 200 mg/kg > ofloxacin 100 mg/kg > (or =) negative control. Therefore, on a weight to weight basis, sparfloxacin was six to eight-fold more active against M. tuberculosis infection in mice than ofloxacin. In addition, WIN 57273, a new broad-spectrum fluoroquinolone, at a dosage of 100 mg/kg daily, was inactive against M. tuberculosis infection.