Efficacy of moxalactam in an animal model of subcutaneous abscesses: penetration into infected sites and in vivo activity against Bacteroides fragilis.

Moxalactam was compared with alternative antimicrobial agents for in vivo activity against Bacteroides fragilis. Mice were challenged with one of 15 strains and evaluated by quantitative bacteriologic analysis of abscess contents after five days of treatment. Optimal results were achieved with clindamycin, moxalactam, and cefoxitin. The mean decrease in bacteria with these three drugs was significantly greater than with chloramphenicol, cefotaxime, carbenicillin, cephalothin, ampicillin, and cefoperazone. The penetration of antimicrobial agents into subcutaneous abscesses was examined. The mean peak level in sterile abscesses of moxalactam was 27% of the mean peak serum level, a result indicating relatively good penetration compared with other beta-lactam antimicrobial agents. Stability of moxalactam to the beta-lactamase of B. fragilis was demonstrated in vivo by comparing levels of biologically active drug in sterile and infected abscesses and in vitro by comparing levels of antibiotic incubated in sterile exudate and exudate infected with B. fragilis. Moxalactam compares favorably with clindamycin and cefoxitin in activity against B. fragilis.