<i>Streptococcus pyogenes</i> (Group A streptococcus; GAS) is a human pathogen causing diseases from uncomplicated tonsillitis to life-threatening invasive infections.
Tonsillar disease (recurrent tonsillitis and/or tonsillar hypertrophy) is one of the most common human disorders, with Streptococcus pyogenes (group A beta-hemolytic streptococcus [GAS]) and Haemophilus influenzae representing the most common pathogens.