Role of fimbriae in adherence of Streptococcus pyogenes to pharyngeal epithelial cells

The adherence of bacteria to mucosal surface constitutes the initial, critical step in colonization and infection. Streptococcus Pyogenes (S. pyogenes) is one of the most important bacteria in tonsillitis and pharyngitis. The mode of the adherence of S. pyogenes to pharyngeal epithelial cells and the morphology of S. pyogenes were observed by scanning electron microscopy and transmission electron microscopy. The adherence of S. pyogenes to pharyngeal epithelial cells was mediated by the fimbriae radiating from the surface of the bacteria. The M protein-negative (M-) strain had smooth, bare cell walls, whereas the M protein-positive (M+) strain had an exterior covered by hair-like fimbriae.