Group A beta-hemolytic streptococci (GABHS) are gram-positive bacteria that grow in culture as pairs or chains of variable length. On sheep blood agar they appear as transparent to opaque, round, small colonies surrounded by a zone of complete hemolysis (beta) of red cells. The beta-hemolytic streptococci include the pathogens of Lancefield groups A, C,and G. In contrast, viridans streptococci produce partial (alpha) or no(gamma) hemolysis. Group D streptococci produce variable hemolysis, and S pneumoniae (pneumococcus) produce alpha-hemolysis.

Biologic products elaborated by GABHS are important determinants of virulence. Antibody responses to these antigens sometimes are used to identify these bacteria as the cause of an infection. In addition to hemolysins (including streptolysins O and S), GABHS may elaborate streptokinase, streptodornase,bacteriocins, deoxyribonuclease, exotoxins, hyaluronidase, nicotinamide adenine dinucleotidase, and proteinase.

GABHS causes many types of infections in children (Table 1). Tonsillopharyngitis is by far the most common manifestation in the pediatric population;...

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