General Information: This strain is a serotype M6 isolate cultured from a child with pharyngitis in private elementary school in Pennsilvania, USA. Causes tonsilitis. Streptococci are Gram-positive, nonmotile, nonsporeforming, catalase-negative cocci that occur in pairs or chains. Members of this genus vary widely in pathogenic potential. Most streptococci are facultative anaerobes, and some are obligate anaerobes. Serologic grouping is based on antigenic differences in cell wall carbohydrates, in cell wall pili-associated protein, and in the polysaccharide capsule in group B streptococci. This organism is a member of the normal human nasopharyngeal flora. Streptococcus pyogenes is a group A streptococcus and is the leading cause of uncomplicated bacterial pharyngitis and tonsillitis. This organism is commonly referred to by the lay press as "flesh eating bacteria".