Telithromycin (HMR3647) is a novel ketolide antibiotic that structurally resembles macrolides. Telithromycin belongs to the ketolide family that is characterized by a keto group at position 3 of the macrolide ring and is active against bacteria causing community-acquired pneumonia, acute exacerbation of chronic bronchitis, and acute sinusitis. Telithromycin also has similar immunomodulatory effects as macrolides. Telithromycin can be used for the research of respiratory infections including bronchial asthma.