S-6123 is a highly effective antimicrobial compound classified under the oxazolidinone series, and it acts by selectively inhibiting ribosomal protein synthesis while not affecting DNA or RNA synthesis.

S-6123 demonstrates strong antimicrobial effectiveness against various gram-positive bacteria, including Streptococcus pyogenes, Streptococcus agalactiae, Group C and G streptococci, and both penicillin-susceptible and -resistant Viridans group streptococci. The minimal inhibitory concentrations (MIC) for these bacteria are 16 μg/ml, 32 μg/ml, 16 μg/ml, 16 μg/ml, 8 μg/ml, and 32 μg/ml, respectively.