Josamycin is a macrolide antibiotic originally isolated from S. narbonensis.1 It is active against clinical isolates of the Gram-positive aerobic bacteria S. aureus, S. epidermidis, S. pneumoniae, S. pyogenes, and S. agalactiae (MIC50s = ≤0.39 ?g/ml for all), as well as the Gram-negative anaerobic bacteria Peptococcus, Peptostreptococcus, and Clostridium when used at concentrations of 6.25 ?g/ml.2 It increases survival in mouse models of systemic S. aureus, S. pyogenes, and S. pneumoniae infection with ED50 values of 206.8, 205, and 86.7 mg/kg, respectively.3
1.Osono, T., Oka, Y., Watanabe, S., et al.A new antibiotic, josamyicn. I. Isolation and physico-chemical characteristicsJ. Antibiot. (Tokyo)20(3)174-180(1967) 2.Reese, R.E., Betts, R.F., Goedde, L.W., et al.In vitro susceptibility of common clinical anaerobic and aerobic isolates against josamycinAntimicrob. Agents Chemother.10(2)253-257(1976) 3.Ono, T., Numata, K., Nagate, T., et al.In vitro and in vivo antibacterial activities of clarithromycinChemotherapy42(3)159-169(1996)