Culture-based bacterial evaluation of the appendix lumen in patients with and without acute appendicitis

Controversy exists over whether bacterial flora within the appendix differs between patients with and without appendicitis. To examine these potential differences, we cultured the appendiceal luminal microbiota of patients with and without acute appendicitis, and identified the bacterial species therein. Fifty-seven patients with acute appendicitis and 37 patients without acute appendicitis who underwent curative resection of colorectal cancer and prophylactic appendectomies (control group) were included. Appendicitis patients were classified into the phlegmonous group or the gangrenous appendicitis group histopathologically. There was no patient with perforated appendicitis. Aerobic isolates were identified using standard identification schemata, and anaerobic isolates were identified according to the Japanese guidelines. There were no significant differences among the three groups in the median number aerobe species present per patient. However, the median number anaerobe species in the gangrenous appendicitis group was significantly higher than that of the control group and the phlegmonous appendicitis group. In addition, the incidence of patients with Bacillus species, Fusobacterium nucleatum, and Bilophila wadsworthia increased as the disease progressed from phlegmonous to gangrenous appendicitis. The present results suggest that increased diversity of anaerobes and the translocation of Bacillus species, F. nucleatum, and B. wadsworthia are associated with the progression of acute appendicitis.