Effects of muramyl dipeptide and clindamycin in a murine abdominal abscess model

Abstract Peritonitis and subsequent local and remote complications are an important source of morbidity and mortality, which persist despite the best available treatment. Reasonable therapeutic efforts, therefore, have included stimulation of host defenses with immune adjuvants, recently typified by muramyl dipeptide (MDP). Murine abdominal abscesses were created by intraperitoneal injection of Bacteroides fragilis and autoclaved fecal suspensions, and the effects of MDP and clindamycin on these abscesses were evaluated. At 10 4 colony-forming units (CFU) per milliliter of Bacteroides fragilis , intraperitoneal clindamycin was effective in reducing both the incidence of abscess formation as well as the number of abscesses per mouse as compared with controls at doses of 5 mg/kg and 2 mg/kg ( P P 7 and 10 8 CFU/ml, pretreatment with MDP increased abscess formation ( P P Bacteroides fragilis , but clindamycin abolished this effect and reduced the number of abscesses to similar levels in both the clindamycin alone and clindamycin + MDP groups. This also occurred at the lower 10 4 CFU dose and thus clindamycin reduction of live bacteria prevented the necessary stimulus for increased abscess formation seen in the MDP alone animals.