Telithromycin as a new antibiotic used for treatment of respiratory tract infections. Telithromycin is the first member of a new family of the macrolide-lincosamide-streptogramin-B (MLSB) class of antimicrobials, the ketolides. It has a good spectrum of activity against respiratory pathogens, including penicillin- and erythromycin-resistant pneumococci as well as intracellular and atypical bacteria. Furthermore, it has a low potential to select for resistance or induce crossresistance among other MLSB antimicrobials. Telithromycin is well tolerated in patients.