Background:

KB-5246 is a tetracyclic quinolone and displays antibacterial activities.

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[1].

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[1].

[1]. Kotera Y, et al. In vitro and in vivo antibacterial activities of KB-5246, a new tetracyclic quinolone. Antimicrob Agents Chemother. 1989 Nov;33(11):1896-900.