Molecular mechanisms of adhesion of Streptococcus pneumoniae to human oropharyngeal epithelial cells.

Adherence of bacteria to mucosal surfaces is an early step in colonization and infection. Streptococcus pneumoniae colonizes the nasopharynx and causes localized and systemic disease. The higher adhesion capacity of strains isolated from patients with otitis as compared to strains from sepsis or meningitis patients indicates that binding to the nasopharyngeal mucosa is important in localized but not in invasive infections. The biochemical basis of the pneumococcal binding to epithelial cells has been investigated. Human nasopharyngeal epithelial cells were mixed with pneumococci, and adherence was determined microscopically. Inhibition of adherence with analogues of epithelial cell receptors was tested by preincubation of pneumococci before the addition of the epithelial cells. Competitive inhibition with glycoconjugates, representing receptor structures on the epithelial cell surface, showed receptor function of saccharides containing the disaccharide GlcNAcbeta1 leads to 3Galbeta-.