ANTIBACTERIAL ACTIVITY OF RU-64004 (HMR-3004), A NOVEL KETOLIDE DERIVATIVE ACTIVE AGAINST RESPIRATORY PATHOGENS

The antibacterial activity of RU 64004, a new ketolide, was evaluated against more than 600 bacterial strains and was compared,vith those of various macrolides and pristinamycin. RU 64004 had good activity agai nst multiresistant pneumococci, whether they were erythromycin A resis tant or not, including penicillin-resistant strains, RU 64004 inhibite d 90% of pneumococci resistant to erythromycin A and penicillin G at 0 .6 and 0.15 mu g/ml, respectively, Unlike macrolides, RU 64004 did not induce the phenotype of resistance to macrolides-lincosamides-strepto gramin B, Its good antibacterial activity against multiresistant pneum ococci ran in parallel with its well-balanced activity against all bac teria involved in respiratory infections (e.g,, Haemophilus influenzae , Moraxella catarrhalis, Streptococcus pyogenes), In contrast to all c omparators (14- and 16-membered-ring macrolides and pristinamycin), RU 64004 displayed high therapeutic activity in animals infected with al l major strains, irrespective of the phenotypes of the strains, The re sults suggest that RU 64004 has potential for use in the treatment of infections caused by respiratory pathogens including multiresistant pn eumococci.