IN-VITRO ACTIVITY OF RU-64004, A NEW KETOLIDE ANTIBIOTIC, AGAINST GRAM-POSITIVE BACTERIA

The comparative in vitro activity of RU 64004 (also known as HMR 3004) , a new ketolide antibiotic, was tested qv agar dilution against appro ximately 500 gram-positive organisms, including multiply resistant ent erococci, streptococci, and staphylococci. All streptococci were inhib ited by less than or equal to 1 mu g of RU 64004 per ml, The ketofide was more potent than other macrolides against erythromycin A-susceptib le staphylococci and was generally more potent than clindamycin agains t erythromycin A-resistant strains susceptible to this agent, Clindamy cin-resistant staphylococci (MIC, >128 mu g/ml) proved resistant to th e ketolide, but some erythromycin A- and clindamycin-resistant enteroc occi remained susceptible to RU 64004.