A macrolide antibiotic; active against a variety of Gram-positive and Gram-negative bacteria (MICs = 0.04-0.8 μg/ml) but not against K. pneumoniae, S. typhimurium, or E. coli with MICs ranging from 5 to >10 μg/ml; active against penicillin-susceptible and -resistant S. pyogenes (MICs = 0.8 and 3.2 μg/ml, respectively) and S. faecalis (MIC = 0.8 μg/ml)