IN-VITRO ACTIVITIES OF 2 GLYCYLCYCLINES AGAINST GRAM-POSITIVE BACTERIA

The glycylcyclines designated CL 329,998 and CL 331,002 are N,N-dimeth ylglycylamido derivatives of minocycline and 6-demethyl-6-deoxytetracy cline, respectively. In vitro activities of these two antimicrobial ag ents were compared with those of tetracycline, minocycline, and seven other antimicrobial agents against 412 gram-positive organisms. Both n ew drugs were significantly more active than minocycline against methi cillin-resistant Staphylococcus aureus (MICs for 90% of isolates teste d, 0.25 and 0.5 mu g/ml versus 4 mu g/ml). CL 329,998 inhibited all st reptococci, lactobacilli, and Leuconostoc spp. at concentrations of le ss than or equal to 0.5 mu g/ml, with CL 331,002 slightly less active against some species. All enterococci, including minocycline-resistant and multidrug-resistant isolates, were inhibited at less than or equa l to 0.5- and less than or equal to 1.0-mu g/ml concentrations of the new drugs, respectively. Only bacteriostatic activity was evident by l ime-kill curves. The two glycylcyclines demonstrated activities in vit ro that were superior to those of minocycline against several gram-pos itive bacterial species, and at relatively low concentrations, they in hibited isolates resistant to both tetracycline and minocycline.