Reaction of clinical isolates and typed strains of the family Bacteroidaceae with rabbit anti-Bacteroides sera examined by radial immunodiffusion.

Antisera were produced which were reactive with Bacteroides fragilis, B. gingivalis, or B. melaninogenicus subsp. melaninogenicus. Anti-B. gingivalis serum exhibited strong reactions with strains of homologous species and reacted with only one other species, B. thetaiotaomicron. Antigens shared by organisms of the B. fragilis group and B. melaninogenicus subspecies of the Bacteroidaceae must be considered when serological methods are used for their identification.

Haemolysis of human erythrocytes by the Fusobacterium nucleatum associated with periodontal disease.

Fusobacterium nucleatum and Bacteroides gingivalis are associated with oral disease. They both attach to haemagglutinate and human erythrocytes. Experiments were performed to determine whether haemolysis would occur following attachment of strains of F. nucleatum and Bacteroides species including B. gingivalis. The F. nucleatum strains consistently displayed both haemagglutination and haemolytic activity. The B. gingivalis strains and other Bacteroides species displayed haemagglutination but no measurable haemolytic activity. Varying the concentration of the F. nucleatum whole cells in the standard haemolysis assay suggested a F. nucleatum-erythrocyte binding site interaction. The haemolytic moiety was observed in various cell, cell wall and lipopolysaccharide extracts.