Bacteroides fragilis-induced intra-abdominal abscess in an experimental model treated with telithromycin (HMR 3647)

Background: Telithromycin (HMR 3647), a novel ketolide, is known to have ac tivity against Bacteroides fragilis in vitro. Methods: We tested this ketol ide in an animal model of intra-abdominal abscess produced by intraperitone al injection of B. fragilis with sterile feces and BaSO4 mixture. Telithrom ycin was tested at two doses, 1.25 and 2.0 mg/dose twice daily, and compare d with clindamycin, cefotetan or metronidazole, all given at 2.0 mg/dose tw ice daily for 10 days. Absence of bacteria at the infected site was conside red a cure and a positive culture considered a failure. Results: The cure r ate was 18% (5/28) on saline therapy, 74% (20/27) on telithromycin and 82% (23/28) on clindamycin, whereas it was 61% (17/28) on metronidazole and 59% (16/27) on cefotetan therapy. A high tissue antibiotic concentration (3-5 times the MIG) of telithromycin was found and this is presumably related to its superior efficacy. Delayed therapy initiated 7 days after infection in stead of immediate therapy cured only 32% of the animals treated. The lower dose of telithromycin (1.25 mg/dose twice daily) was as effective as the h igher dose (2 mg/ dose twice daily). Conclusions: We found that telithromyc in is as effective as clindamycin and more effective than metronidazole and cefotetan in this experimental model. These results suggest that telithrom ycin may be tested in future for the treatment of B. fragilis infections in humans. Copyright (C) 2001 S. Karger AG, Basel.