An oxazolidinone-type antibiotic; has activity against a panel of C. difficile strains (MICs = 0.125-0.5 μg/ml); inhibits toxin A and B formation in stationary-phase cultures and spore formation in late exponential cultures of the toxigenic C. difficile strain ATCC 9689; inhibits C. difficile protein synthesis (IC50s = 0.08-0.31 μg/ml); increases survival in a mouse model of CDAD at 1 and 10 mg/kg; increases survival in a hamster model of CDAD at >3 mg/kg