Definition of Group A
: any of various strains of a streptococcus (Streptococcus pyogenes) that include the causative agents of pharyngitis, scarlet fever, septicemia, some skin infections, rheumatic fever, and glomerulonephritis —usually used attributively <Group A strep throat>
First Known Use of group a
Medical Definition of Group A
: the Lancefield group of beta-hemolytic streptococci that comprises all strains of a species of the genus Streptococcus (S. pyogenes) and that includes the causative agents of pharyngitis, scarlet fever, septicemia, some skin infections (as pyoderma and erysipelas), rheumatic fever, and glomerulonephritis—usually used attributively <Group A streptococcal infections>; compare group b
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