A macrolide antibiotic; active against five strains EAch of Staphylococcus and Streptococcus (geometric mean MICs = 0.08 and 0.79 UG/ml, respectively), as well as several strains EAch of Corynebacterium, Haemophilus, and S. pneumoniae (MIC50s = 0.02, 0.01, and 2.5 UG/ml, respectively); protective against infection by strains of S. aureus, S. pyogenes, S. pneumoniae, or L. monocytogenes in mice (PD50s = 23-98 mg/kg)