Gram-Negative Bacilli of the Genus Bacteroides

Abstract

A cultural, morphological, and serological study was made of 11 gram-negative strains of Bacteroides isolated from human inflammatory lesions. Of these, 4 corresponded closely to the published descriptions of Bacteroides jragilis, and 6 resembled Bacteroides jundulijormis. The authors could not find a previous description of a strain of another species, here designated Bacteroides A. B. jragilis and B. jundulijormis are the only species of this genus which the authors have encountered to which a definite pathogenic role can be attributed. These 2 species can be differentiated by their morphology and by biologic and serologic tests. Of the 4 strains of B. jragilis studied, 3 seemed identical serologically; the 4th strain belonged to a different serologic group. The 6 strains of B. jundulijormis fall into 1 serologic group. However, the difficulties attendant on the production of satisfactory antigens make it wise to interpret the results of agglutination tests with caution. B. jundulijormis has been more commonly obtained by the authors in pure culture from lesions where it is obviously the only pathogen present, and in all but one of the cases in which they have found it, the result has been fatal.