| Abstract: | Bacteroides fragilis is frequently recovered from cases of appendicitis with perforation and from infections developing secondary to appendicitis. In order to assess the part played by B. fragilis in the aetiology of appendicitis, quantitative aerobic and anaerobic culture studies of the contents of 49 inflammated appendices were performed. Anaerobic gram-negative non-sporing rods were cultivated from 43 appendices in the range 10(3)-10(9)/g. A total of 1,473 isolates was differentiated by biochemical methods, and 1,374 cultures were found to belong to the saccharolytic species of the genus Bacteroides (B. fragilis, B. thetaiotaomicron, B. vulgatus, B. distasonis etc.). B fragilis was detected in 31 appendices; the species predominated in 18 samples. B theraiotamicron, recovered from 27 samples, was prevalent in 4 appendices. In one sample, B. fragilis and B. thetaiotaomicron outnumbered the other appendicular bacterial. B. vulgatus was cultivated from 12 appendices, but did once constitute the prevalent group. It has been previously shown that B. vulgatus (43% of intestinal isolates) and B. thetaiomicron predominate in the normal narge bowel flora. On the other hand, approximately 80% of pyrogenic Bacteroides strains belong to B. fragilis, B. thetaiotaomicron accounting for 19% and B. vulgatus being virtually absent. From these striking differences in species distribution the conclusion was drawn that B. fragilis possesses the highest virulence for man. Species distribution within the 1,374 appendicular isolates of saccharolytic Bacteroides (percentages of 62, 19 and 4.3 for B. fragilis, B. thetaiotaomicron, and B. vulgatus, respectively) was very similar to that encountered in clinical specimens. From the results obtained it becomes evident that pyrogenic Bacteroides, in particular B. fragilis, plays an important role in nearly 50% of cases of appendicitis. |
