Polysaccharide-mediated protection against abscess formation in experimental intra-abdominal sepsis

J Clin Invest. 1995 Dec;96(6):2727-31. doi: 10.1172/JCI118340.


Abscess formation is a major complication of intra-abdominal sepsis that causes significant morbidity and mortality. In such cases, Bacteroides fragilis is the predominant anaerobic isolate. In a rat model of intra-abdominal sepsis, the capsular polysaccharide complex (CPC) from B. fragilis promotes abscess formation and when administered sub-cutaneously, protects against this host response by a T cell-dependent immune mechanism. In the present study, the polysaccharide A (PS A) component of CPC protected animals against challenge with live heterologous bacterial species (mixtures of anaerobes and facultative organisms) that are most commonly isolated from intra-abdominal abscesses in humans. Protection against heterologous bacterial challenge was transferred by T cells. Administration of PS A shortly before or even after challenge with B. fragilis protected against this host response. In experiments designed to simulate fecal contamination of the human peritoneal cavity, PS A protected animals against abscess formation induced by a rat cecal contents inoculum. The surprisingly broad protective activity of PS A indicates that this molecule is likely suppressing a nonspecific host tissue reaction that forms in response to a variety of abscess-inducing organisms and that it might be useful in preventing abscess formation associated with intra-abdominal sepsis in the clinical setting.

MeSH terms

  • Abdominal Abscess / immunology
  • Abdominal Abscess / prevention & control*
  • Animals
  • Bacteremia / immunology
  • Bacteremia / prevention & control*
  • Bacteroides Infections / immunology
  • Bacteroides Infections / prevention & control*
  • Bacteroides fragilis* / immunology
  • Cross Reactions
  • Disease Models, Animal
  • Enterobacter / immunology
  • Feces / microbiology
  • Humans
  • Immunization*
  • Male
  • Polysaccharides, Bacterial / pharmacology*
  • Rats
  • Rats, Wistar
  • T-Lymphocytes / immunology


  • Polysaccharides, Bacterial