Therapeutic efficacy and pharmacokinetic properties of rifampicin in a Bacteroides fragilis intra-abdominal abscess

The efficacy of rifampicin in treating a Bacteroides fragilis infection was investigated and compared to clindamycin and metronidazole in an experimental model of intra-abdominal abscess in mice. Rifampicin, when given subcutaneously, showed activity superior to that of clindamycin in reducing the incidence of abscess formation as well as the number of Bacteroides organisms recovered from the abscess, and rifampicin was comparable in efficacy to metronidazole when given orally at the same dose level. The comparative pharmacokinetic properties of rifampicin and clindamycin demonstrated that the peak serum and abscess levels reached with rifampicin were significantly higher than those of clindamycin. The half-life of rifampicin in serum and in the abscess was longer than that of clindamycin.