An Electron Microscope Study of <i>Bacteroides nodusus</i> : Ultrastructure of Organisms from Primary Isolates and Different Colony Types

Abstract

Examination of the ultrastructure of strains of Bacteroides nodosus isolated from cases of ovine foot‐rot shows the organism to be highly piliated on primary culture. On subculture in the laboratory two colony types characterized by a high and low degree of piliation can be demonstrated. In agglutination tests the interaction of pili with antibody is responsible for high titre homologous agglutination. Low titre heterologous agglutination appears to be due to other surface antigens. These findings are discussed in relation to the pathogenicity of the organism.