Lefamulin acetate (BC-3781 acetate) (formally BC-3781 acetate) is a novel pleuromutilin antibiotic and is the first to be used for the systemic treatment of bacterial infections in humans. Lefamulin acetate (BC-3781 acetate) inhibits protein synthesis by binding to the peptidyl transferase center of the 50S bacterial ribosome, preventing the binding of transfer RNA for peptide transfer. Lefamulin acetate (BC-3781 acetate) is an orally active antibiotic for community-acquired bacterial pneumonia (CABP) treatment.

Lefamulin对革兰阴性菌有抗菌作用，包括流感嗜血杆菌（MIC50=1 μg/ml；MIC90=0.12 μg/ml）和摩拉氏卡他球菌（MIC50=2 μg/ml；MIC90=0.25 μg/ml）[1]。Lefamulin acetate（BC-3781 acetate）对耐药的革兰阳性菌也有抗菌活性，包括金黄色葡萄球菌（MRSA）（MIC50=0.12 μg/ml；MIC90=0.25 μg/ml）；β-溶血性链球菌（MIC50=0.03 μg/ml；MIC90=0.03 μg/ml）；绿色链球菌群（MIC50=0.12 μg/ml；MIC90=0.5 μg/ml）；粪肠球菌（MIC50=0.12 μg/ml；MIC90=4 μg/ml）；肺炎链球菌（MIC50=0.12 μg/ml；MIC90=0.25 μg/ml）[1]。