A fluoroquinolone antibiotic; active against S. aureus, E. coli, P. aeruginosa, P. morganii, K. pneumoniae, and E. cloacae in vitro (MICs = 0.78, 0.78, 12.5, 1.56, M. luteus DNA gyrase (IC50 = 1.5 mM); inhibits DNA synthesis in S. aureus, E. coli, P. aeruginosa, K. pneumoniae, and E. cloacae (IC50s = 0.93, 1.03, 38.8, 0.55, and 0.66 μg/ml, respectively); reduces bacterial burden in the spleen and liver in a mouse model of systemic S. typhimurium infection at 50 mg/kg, p.o.