Throat
Streptococcal pharyngitis is acquired by inhaling aerosols emitted by infected individuals. The symptoms reflect the inflammatory events at the site of infection. A few (1-3%) people develop rheumatic fever weeks after the infection has cleared.
Skin
Impetigo involves the infection of epidermal layers of skin. Pre-pubertal children are the most susceptible. Cellulitis occurs when the infection spreads subcutaneous tissues. Erysipelas is the infection of the dermis. About 5% of patients will develop more disseminated disease. Necrotizing fasciitis involves infection of the fascia and may proceed rapidly to underlying muscle.
Systemic
Scarlet fever is caused by production of erythrogenic toxin by a few strains of the organism.
Toxic shock is caused by a few strains that produce a toxic shock-like toxin.
Non-suppurative Sequelae
Some of the antibodies produced during the above infections cross-react with certain host tissues. These can indirectly damage host tissues, even after the organisms have beencleared, and cause non suppurative complications.
Rheumatic fever. M protein cross reacts with sarcolemma. Antibodies cross-react with heart tissue, fix complement, and cause damage.