Adhesion of Actinomyces Isolates to Experimental Pellicles

Abstract

The ability of oral bacteria to adhere to surfaces is associated with their pathogenicity. Actinomyces can adhere to pellicle and cells through extracellular fimbriae. Research on adhesion of actinomyces has been conducted with use of hydroxyapatite (HA) coated with mammalian-derived salivary constituents, whereas the bacterial-derived components of the acquired pellicle have been largely ignored. The influence of the cell-free bacterial enzyme, glucosyltransferase (GTF), on adhesion of human and rodent isolates of Actinomyces viscosus was examined. Cell-free GTF was adsorbed onto parotid saliva-coated hydroxyapatite (sHA). Next, A. viscosus was exposed to the pellicle following the synthesis of glucan formed in situ by GTF. Glucans formed on the pellicle served as binding sites for adhesion of a rodent strain of A. viscosus. Conversely, the presence of in situ glucans on sHA reduced the adhesion of human isolates of A. viscosus compared with their adhesion to sHA. Adhesion of the rodent strains may be facilitated through a dextran-binding protein, since the rodent strains aggregated in the presence of dextrans and mutan. The human isolates were not aggregated by dextran or mutan. Pellicle harboring A. viscosus rodent strains interfered with the subsequent adhesion of Streptococcus mutans to the bacterial-coated pellicle. In contrast, the adhesion of S. mutans to pellicle was not decreased when the pellicle was pre-exposed to a human isolate of A. viscosus. The experimental data suggest that human and the rodent isolates of A. viscosus have distinct glucan adhesion properties.(ABSTRACT TRUNCATED AT 250 WORDS)