In vitro and in vivo antibacterial activities of clarithromycin.

The in vitro and in vivo antibacterial activities of clarithromycin (CAM), a new oral macrolide antibiotic, were compared with those of erythromycin (EM), josamycin (JM) and rokitamycin (RKM). The antibacterial spectrum and in vitro activities of CAM were similar to those of EM. Therapeutic efficacies of CAM against various experimental infections in mice--including systemic infections caused by gram-positive bacteria such as Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae, and subcutaneous abscess due to S. aureus, and bacterial pneumonia caused by S. pneumoniae--were superior to those of EM, JM and RKM. CAM exhibited higher serum levels than EM in mice after a single oral dose of 50 mg/kg.