Gram positive cocci in chains, beta-hemolytic
Reservoir is human skin and oropharynx/mucous membranes, colonizes 10% in pharynx, more commonly children.
Person-to-person transmission, occasionally foodborne.
Exhaustive and fascinating list.
Most common manifestations tonsillopharyngitis ("strep throat") and skin infections (impetigo, erysipelas, cellulitis).
Invasive infections such as bacteremia, endocarditis, necrotizing fasciitis, meningitis, toxic shock syndrome, pneumonia, and other sterile space infections.
Post-infectious immunologically mediated phenomena such as glomerulonephritis and rheumatic fever.
Scarlet fever and others.