KB-5246 is a tetracyclic quinolone and displays antibacterial activities. The MICs for 90% of isolates tested (MIC90s) of KB-5246 against gram-positive microorganisms such as
Staphylococcus aureus
, including methicillin-resistant S.
aureus
,
Staphylococcus epidermidis
,
Streptococcus pneumoniae
, and
Streptococcus pyogenes
, are 0.39 μg/mL. KB5246 inhibits 90% of isolates of
Escherichia coli
,
Klebsiella pneumoniae
,
Klebsiella oxytoca
at a concentration of 0.10 μg/mL or less. When a concentration of KB-5246 at the MIC or higher is added, no regrowth after 24 h of incubation is observed.
The 50% effective dose values of KB-5246 against S.
pneumoniae
2132 infections are 50.5 mg/kg of body weight. The activities of KB-5246 against S.
aureus
Smith, P.
aeruginosa
GN11189, and
Serratia marcescens
GN7577 infections are comparable to those of ofloxacin and greater than those of norfloxacin.