A pharmaceutical composition according to one aspect comprises an oxazolidinone derivative or a pharmaceutically acceptable salt thereof, and thus can exhibit excellent prophylactic or therapeutic effects on diseases mediated by
bacteria having resistance to
penicillin-based compounds, and in particular, when used in combination with one or more
antibiotics, can exhibit excellent effects such as an increase in overall
healing rate,
elimination of mediating
bacteria, inhibition of an increase in severity, inhibition of occurrence of adverse events, an increase in safety, an increase in
tolerability, and the like. Accordingly, the composition can be used as a therapeutic agent for
penicillin-based compound-
resistant bacteria-mediated diseases such as
bacteremia,
sepsis,
endocarditis, and the like.