IN-VITRO ACTIVITY OF DU-6859A AGAINST ANAEROBIC-BACTERIA

The activity of a new quinolone agent, DU-6859a, against 330 strains o f anaerobic bacteria was determined by using the National Committee fo r Clinical Laboratory Standards-approved Wadsworth brucella laked bloo d agar method; the activity of DU-6859a was compared with those of amo xicillin-clavulanate (2:1), chloramphenicol, ciprofloxacin, clindamyci n, fleroxacin, imipenem, lomefloxacin, metronidazole, sparfloxacin, an d temafloxacin. DU-6859a and chloramphenicol inhibited all of the isol ates at concentrations of 1 and 16 mu g/ml, respectively; amoxicillin- clavulanate, imipenem, and metronidazole inhibited greater than or equ al to 94% of the isolates at their respective breakpoints (8, 8, and 1 6 mu g/ml); MICs of DU-6859a at which 90% of the strains were suscepti ble were 1 to 5 twofold dilutions lower than those of the other quinol ones for every group of organisms. MICs of DU-6859a at which 90% of th e strains were susceptible (total numbers of strains tested are in par entheses) were less than or equal to 0.25 mu g/ml for Bacteroides frag ilis (57), other B. fragilis group species (84), Bilophila wadsworthia (15), Clostridium species (27) (including C. difficile, C. perfringen s, and C. ramosum), Fusobacterium nucleatum (16), Fusobacterium mortif erum-F. varium group species (10), Peptostreptococcus species (20), no n-spore-forming gram-positive rods (20), and Prevotella species (25).