ADHERENCE TO HUMAN BUCCAL EPITHELIAL-CELLS BY STREPTOCOCCUS-MITIS

The mechanism for adherence of Streptococcus mitis to human buccal epithelial cells was studied in vitro. The optimal conditions for such adherence were incubation for 60 min at 37-degrees-C, pH of 7-8, and a ratio of bacterial to epithelial cells of 200:1. Eight bacterial cells were attached per epithelial cell under these conditions. Saliva-coating S. mitis increased adhesion by approximately four-fold. A reduction of the adherence was observed when bacterial cells were coated with heat- or trypsin-treated saliva. The adherence of saliva-coated S. mitis was almost completely inhibited by N-acetylneuraminic acid, and to some extent by glucose and galactose. Treatment of saliva-coated bacterial cells by divalent cations or a chaotropic anion had no effect on adherence to these cells. Thus, it would appear that glucose, galactose and especially N-acetylneuraminic acid sensitive lectins are important in the adherence mechanism of S. mitis.