Objective To evaluate the in vitroantibacterial activity of
erythromycin cyclic 11,12-carbonate. Methods The minimal inhibitory
concentrations (MICs) of domestic and imported
erythromycin cyclic 11,12-carbonate against clinical isolates of bacteria were tested by standard agar dilution method in comparison with erythromycin, roxithromycin, clarithromycin, dirithromycin, azithromycin and acetylspiramycin. Results The antibacterial activities of domestic and imported erythromycin cyclic 11,12-carbonate against Gram-positive and an aerobic bacteria were two to eight times stronger than that of erythromycin, superior to those of roxithromycin, clarithromycin, dirithromycin, azithromycin and acetylspiramycin, but inferior to that of azithromycin against Gram-negative bacteria. Erythromycin cyclic 11,12-carbonate was bacteriostatic against S.aureus, but bactericidal against S.pyogenesat two to four times the MIC.
Antibacterial activity of erythromycin cyclic 11,12-carbonate was enhanced at pH of 5 to 9 against S.aureusand S.pyogenes. The inoculum size and serum have no effect on the MICs of erythromycin cyclic 11,12-carbonate against S.aureusand S.pyogenes. Conclusion Erythromycin cyclic 11,12-carbonate had potent in vitroantibacterial activities. The activity of domestic erythromycin cyclic 11,12-carbonate was similar to that of imported one, superior to those of erythromycin, roxithromycin, clarithromycin, dirithromycin, azithromycin and acetylspiramycin.