title: Pathogenesis of intraabdominal abscess formation: abscess-potentiating agents and inhibition of complement-dependent opsonization of abscess-inducing bacteria.
abstract: Bacteroides fragilis and Escherichia coli are synergistic in the production of intraabdominal abscesses. However, these bacteria initiate abscess formation only when inoculated with an agent such as autoclaved colonic contents (ACC) or bran (a fiber analogue). The mechanism of action of the abscess-potentiating agent was studied. Opsonins in normal mouse serum were determined for phagocytic killing by murine neutrophils of B. fragilis and E. coli. Opsonization required fixation of complement by the alternative pathway. ACC (0.2 mg/ml) and bran (1.0 mg/ml) inhibited phagocytic killing of Proteus mirabilis in the presence of normal but not immune serum. Assay of the alternative pathway of complement activation indicated that both bacterial components and abscess-potentiating agents in an abscess-inducing mixture activated complement. These findings suggest that abscess-potentiating agents inhibit opsonization and therefore the subsequent phagocytic killing of bacteria in the nonimmune host.
authors.affiliation: Department of Microbiology and Infectious Diseases, School of Medicine, Flinders University of South Australia, Adelaide.
authors.forename: J J
authors.initials: JJ
authors.lastname: Finlay-Jones
authors.forename: P A
authors.initials: PA
authors.lastname: Kenny
authors.forename: M F
authors.initials: MF
authors.lastname: Nulsen
authors.forename: L K
authors.initials: LK
authors.lastname: Spencer
authors.forename: N L
authors.initials: NL
authors.lastname: Hill
authors.forename: P J
authors.initials: PJ
authors.lastname: McDonald
mesh_terms: D000038:Abscess / Q000209:etiology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001442:Bacteroides Infections / Q000209:etiology*; D001441:Bacteroides fragilis / Q000276:immunology*; D003170:Complement Pathway, Alternative; D004043:Dietary Fiber / Q000276:immunology; D004926:Escherichia coli / Q000276:immunology; D004927:Escherichia coli Infections / Q000209:etiology*; D005455:Fluorescent Antibody Technique; D005766:Gastrointestinal Contents; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009895:Opsonin Proteins / Q000097:blood; D010532:Peritoneal Diseases / Q000209:etiology*; D010587:Phagocytosis; D011513:Proteus mirabilis / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D004043:Dietary Fiber; D009895:Opsonin Proteins