Experimental intraabdominal
abscesses were produced in mice by
intraperitoneal injection of Bacteroides fragilis and Pseudomonas aeruginosa. The therapeutic efficacy of
rifampicin and
cefsulodin alone, and in combination was investigated in this in-vivo experimental mixed intraabdominal
abscess model. Treatment with
rifampicin at 10, and 25 mg/kg or
cefsulodin at 50, and 100 mg/kg singly or in combinations prevented mortality as compared to 68% mortality rate occurring in the untreated mice.
Rifampicin, at 25 mg/kg dose, was very effective in preventing
abscess formation and produced bacterial eradication. It prevented
abscess formation in 80% of the mice and eradicated both Bacteroides and Pseudomonas in 100% and 75% of the
abscesses of the mice.
Cefsulodin failed to reduce the incidence of
abscess formation, and to eradicate Bact. fragilis from the
abscesses, although it significantly decreased Ps. aeruginosa in the
abscesses. The combination of
rifampicin at 10 mg/kg and
cefsulodin at 100 mg/kg was more effective than either of the
antibiotics alone and was as effective as
rifampicin alone at 25 mg/kg levels. This combination was bactericidal against both organisms in the infected mice.