CHARACTERISTICS OF AN UNUSUAL ANAEROBIC PIGMENTED GRAM-NEGATIVE ROD ISOLATED FROM NORMAL AND INFLAMED APPENDIXES

During our studies of the bacterial etiology of appendicitis, we often isolated a previously undescribed anaerobic gram-negative rod. This o rganism resembled the Bacteroides fragilis group because it was resist ant to bile and because of its special-potency-disk pattern (resistant to vancomycin, kanamycin, and colistin), but unlike the B. fragilis g roup, this bacterium produced brown pigment on media containing hemoly sed blood. The cellular fatty acid pattern, with iso-C15:0 being the p redominant acid, was most closely related to the fatty acid profile of Porphyromonas species; however, this organism differed from Porphyrom onas species by being bile-resistant and by not producing butyrate as a metabolic endproduct. Enzymatic activities of 31 isolates were deter mined with use of the API ZYM system and Rosco diagnostic tablets. The se profiles were different from those of Prevotella, Porphyromonas, an d related species. This organism was isolated from 40% of appendiceal tissue samples; no obvious qualitative or quantitative difference in r ates of isolation from patients with inflamed or normal appendices was observed.