Background: The aim of this study was to investigate whether there is a relationship between enterotoxin-producing B. fragilis strains and toxigenic C. difficile strains and the pathogenesis of acute appendicitis.
Material/Methods: Post-appendectomy tissues from 34 patients with histopathologically confirmed phlegmonous or gangrenous appendicitis were studied.
Results: Among 86 anaerobes isolated, the B. fragilis group was most frequently isolated: 34 B. fragilis strains were cultured from 21 post-appendectomy tissues. Two enterotoxin-producing B. fragilis strains were found. Enterotoxin titers (1:10 and 1:160, respectively) were measured on HT29/C cells. The presence of the enterotoxin gene was confirmed by PCR in DNA extracted from both strains. Among 21 DNA samples isolated from those post-appendectomy tissues from which B. fragilis strains were cultured, the presence of the enterotoxin gene was confirmed in only one case (the corresponding B. fragilis strain enterotoxin titer was 1:160). A unique toxigenic C. difficile strain was also cultured from the tissue of an adult patient with gangrenous non-perforated appendicitis. The presence of toxin A and toxin B genes was confirmed by PCR in DNA extracted from the C. difficile strain, but these genes were not found in the DNA extracted from the corresponding tissue.
Conclusions: The presence of enterotoxigenic B. fragilis and toxigenic C. difficile strains was shown in post-appendectomy tissue from patients with phlegmonous and gangrenous appendicitis, and the B. fragilis enterotoxin gene was detected directly in the corresponding tissue. Further investigations (including immunologic aspects) require to confirm the role of these toxins in pathogenesis of acute appendicitis.

Keywords: appendicitis, enterotoxigenic Bacteroides fragilis, Clostridium difficile, PCR