Garenoxacin (12.5-50 mg/kg; s.c.; once) is highly effective against the wild-type strain and mutants harboring a single mutation in a mouse pneumonia model with S. pneumonia infection. Garenoxacin (10 and 30 mg/kg; p.o.; once) reduces the viable cell counts in the lungs and significantly prolongs survival on experimental secondary pneumococcal pneumonia caused by S. pneumoniae D-979 in BALB/c female mice.