KB-5246

Bacterial

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.