In vitro activity of R-95867, the active metabolite of a new oral carbapenem, CS-834, against anaerobic bacteria

The in vitro activity of R-95867, the active metabolite of a new oral carbapenem, CS-834, was compared with those of DU-6859a, cefditoren, ampicillin/sulbactam and clindamycin against a variety of anaerobic bacteria. R-95867 inhibited 90% of anaerobic strains at </=2 mg/L. In general, R-95867 was 2- to 4-fold less active than DU-6859a but more active than other agents tested against strains of peptostreptococci, clostridia, the Bacteroides fragilis group, Porphyromonas spp. and fusobacteria. R-95867 was stable to hydrolysis by beta-lactamase type 2e derived from B. fragilis, Prevotella bivia and Prevotella intermedia, but unstable to hydrolysis by carbapenemase from B. fragilis.