Abstract
When tested by agar dilution on Mueller-Hinton agar supplemented with 5% horse blood, the ketolides HMR 3004 and HMR 3647 were slightly more active (MIC at which 90% of the isolates were inhibited [MIC 90 ], 0.03 μg/ml) against Bordetella pertussis than azithromycin, clarithromycin, erythromycin A, and roxithromycin. Azithromycin (MIC 90 , 0.06 μg/ml) was the most active compound against B. parapertussis . Rifampin and rifapentine were considerably less active.