Contezolid acefosamil sodium (MRX-4), a new and orally active oxazolidinone , is an antibiotic in study for complicated skin and soft tissue infections (cSSTI) caused by resistant Gram-positive bacteria. Contezolid acefosamil sodium (MRX-4) markedly reduces potential for myelosuppression and monoamine oxidase inhibition (MAOI) .