In vitro activity of telithromycin (HMR3647), a new ketolide, against clinical isolates of Mycoplasma pneumoniae in Japan

The in vitro activity of telithromycin (HMR3647), a new ketolide, against M ycoplasma pneumoniae was determined by the broth microdilution test using 4 1 clinical isolates obtained in Japan, as compared with those of five macro lides (erythromycin, clarithromycin, roxithromycin, azithromycin, and josam ycin), minocycline, and levofloxacin. Telithromycin was less potent than az ithromycin, but it was more active than four other macrolides, minocycline, and levofloxacin; its MICs at which 50 and 90% of the isolates tested were inhibited were both 0.00097 mu g/ml, justifying clinical studies to determ ine its efficacy for treatment of M. pneumoniae.