Haemagglutination by the Bacteroides fragilis group

Adhesive properties of five species of Bacteroides were compared by direct haemagglutination with erythrocytes of different origin. Only strains of Bacteroides fragilis agglutinated erythrocytes and different patterns of haemagglutination were observed. None of eight carbohydrates tested inhibited haemagglutination. The activity was destroyed by heat and by periodate treatment, but not by three proteases tested.