Experimental aspects of intraabdominal abscess.

Two animal models were used to examine the bacteriologic aspects and antibiotic treatment of intraabdominal abscess. The first model was designed to simulate the septic complications of colonic perforation using an inoculum of stool implanted intraperitoneally in rats. The results showed that coliforms were responsible for early lethality, Bacteroides fragilis appeared to play a particularly important role in abscess formation, and optimal treatment required antimicrobial regimens directed against both coliforms and anaerobes. The second model was designed to examine the pharmacokinetic properties of antibiotics and therapeutic efficacy of various antimicrobials in a subcutaneous abscess involving B. fragilis in mice. This work showed all drugs penetrated abscesses, although there was a diminishing antimicrobial effect with progressive delays in the time that treatment was initiated. It is suggested that bacteria within an abscess are in a stationary phase of growth so that early institution of treatment is critical for optimal in vivo activity, and bactericidal drugs may be preferred once an abscess has formed.