In vitro activity of the new ketolide HMR 3004 compared to an azalide and macrolides against Streptococcus pneumoniae and Haemophilus influenzae

The purpose of this study was to compare the in vitro activity of a new ketolide, HMR 3004 (RU64004), to that of three macrolides and one azalide against 608 Streptococcus pneumoniae and 202 Haemophilus influenzae. Macrolide-resistant pneumococci were susceptible to HMR 3004, even if they were resistant to clindamycin, Against Haemophilus influenzae, HMR 3004 and azithromycin were nearly identical in potency; the macrolides were 8- to 16-fold less active, HMR 3004 may be useful for treating respiratory tract infections if sufficient concentrations can be achieved at the local sites of infection.