Adhesive properties of strains of Fusobacterium nucleatum of the subspecies nucleatum, vincentii and polymorphum

Abstract

This study surveyed some adhesive properties of strains of Fusobacterium nucleatum representative of the 3 recently defined groups or subspecies that could relate to their colonization and virulence. With one exception, F. nucleatum strains agglutinated sheep erythrocytes, but the quantity of bacteria required and the sensitivity of the hemagglutination reactions to inhibition by 0.05 M galactose or arginine varied between strains, and did not exhibit clear‐cut correlations with subspecies. Neuraminidase treatment of erythrocytes generally enhanced the hem‐agglutinating activity of most strains, but trypsin treatment had no effect. Strains of F. nucleatum also attached in moderate numbers to buccal epithelial cells. Treatment of the epithelial cells with neuraminidase or with trypsin increased the numbers of all Fusobacterium strains that attached. Treatment of hydroxyapatite (HA) beads with submandibular or parotid saliva also promoted the adhesion of all strains of F. nucleatum studied. Treatment of HA with human serum or albumin produced a selective effect. Adhesion of some strains was promoted by serum and albumin treatment, and that of other strains was unaffected. Adhesion of all strains of F. nucleatum was enhanced to statherin‐treated HA, whereas HA treated with salivary pro line‐rich protein‐1 did not foster F. nucleatum attachment. Three of 4 strains of the subspecies vincentii, and each of 2 polymorphum strains studied exhibited strong adhesion to HA treated with either human type I or type IV collagen. However, only 1 of 5 strains of the subspecies nucleatum bound well to collagen‐treated HA. The data obtained indicate that strains of F. nucleatum are heterogeneous in their adhesive properties, and possess different collections of adhesins that mediate their attachment to surfaces. The enhanced attachment of F. nucleatum cells to neuraminidase or trypsin‐treated epithelial cells likely contributes to their increased proportions being associated with poor oral hygiene and gingivitis. In addition, the binding of some F. nucleatum strains to serum or albumin‐treated apatitic surfaces may contribute to their tropism for colonizing subgingival sites, and the ability of some strains to bind to collagen may contribute to their invasive potential.