Attachment of Streptococcus pneumoniae to human pharyngeal epithelial cells in vitro

The aim of this study has been to develop a test system for attachment of pneumococci to pharyngeal cells. Cells scraped from a healthy person were washed and quantitated, bacteria added and after incubation the suspension was washed and the number of adhering bacteria counted. Among strains from different infectious foci the highest number of strains with adhesive capacity was found in the otitis media group. Capacity to attach to the pharyngeal mucosa might be a virulence factor of pneumococci causing otitis media. There was a lack of distinct relation between capsular serotype and adhesive capacity indicating that the polysaccharide is not primarily responsible for the binding to epithelial cells. If attachment to the pharyngeal mucosa is a first step necessary for colonization and subsequent invasion of the tissues, then antibiotics in the secretions preventing such colonization might be of protective value in otitis-prone children.