Comparison of Bacteroides vulgatus strains in the enhancement of experimental ulcerative colitis.

Strains of Bacteroides vulgatus from a variety of sources were tested for their abilities to enhance the inflammatory response in an experimental model for ulcerative colitis. Although there were considerable differences noted in inflammatory responses when guinea pigs were immunized with the various strains, there did not appear to be any correlation between the source of the isolates and the severity of the carrageenan-induced lesions. Strains from patients with ulcerative colitis were no more active in the model system than were strains from patients with antibiotic-associated colitis or strains from a healthy human source. The antibody titer to the strain used for immunization did not correlate with the severity of the cecal ulcerations, as determined by histopathologic evaluation.