Morphology and Ultrastructure of Group A Streptococcus Biofilms.

: Light and electron microscopy enables researchers to study the ultrastructure of GAS biofilms formed on abiotic surfaces. Chains of streptococci surrounded by a bluish film are seen under a light microscope after alcian blue staining of preparations grown on coverslips. The extracellular matrix (indicator of biofilm maturity) becomes visible on ultrathin sections in transmission electron microscopy after additional staining with alcian blue; filamentous structures, characteristic of biofilm, are observed in intercellular spaces. The data obtained by scanning electron microscopy also demonstrate the presence of biofilm.