The most common group A streptococcal (GAS) infection is acute pharyngotonsillitis. Purulent complications, including otitis media, sinusitis, peritonsillar and retropharyngeal abscesses, and suppurative cervical adenitis develop in some patients, usually people who are untreated. The value of antimicrobial therapy for GAS upper respiratory tract disease is to reduce acute morbidity and to decrease nonsuppurative sequelae (acute rheumatic fever and acute glomerulonephritis).

Scarlet fever occurs most often in association with pharyngitis and, rarely, with pyoderma or an infected wound. Scarlet fever has a characteristic confluent erythematous sandpaper-like rash that is caused by one or more of several erythrogenic exotoxins produced by GAS strains. Severe scarlet fever occurs rarely. Other than the occurrence of rash, the epidemiologic features, symptoms, signs, sequelae, and Treatment of scarlet fever are the same as those of streptococcal pharyngitis.

Toddlers (1 through 3 years of age) with GAS respiratory tract infection initially can have serous rhinitis and then develop a protracted illness with moderate fever, irritability, and anorexia (streptococcal fever). The classic presentation of streptococcal upper respiratory tract infection as acute pharyngitis is uncommon in children younger than 3 years of age. Rheumatic fever also is rare in children younger than 3 years of age.

The second most common site of GAS infection is skin. Streptococcal skin infections (ie, pyoderma or impetigo) can result in acute glomerulonephritis, which occasionally occurs in epidemics. Acute rheumatic fever is not a sequela of streptococcal skin infection.

Other GAS infections include erysipelas, perianal cellulitis, vaginitis, bacteremia, pneumonia, endocarditis, pericarditis, septic arthritis, cellulitis, necrotizing fasciitis, osteomyelitis, myositis, puerperal sepsis, surgical wound infection, acute otitis media, sinusitis, mastoiditis, and neonatal omphalitis. Invasive GAS infections can be severe, with or without an identified focus of local infection, and can be associated with streptococcal toxic shock syndrome or necrotizing fasciitis. Infection can follow minor or unrecognized trauma. An association between GAS infection and sudden onset of obsessive-compulsive and/or tic disorders-pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS)-has been proposed but is unproven.

Streptococcal toxic shock syndrome (TSS) is caused by toxin-producing GAS strains and typically manifests as an acute illness characterized by fever, generalized erythroderma, rapid-onset hypotension, and signs of multiorgan involvement including rapidly accelerated renal failure (see Table 3.69). Evidence of local soft tissue infection (eg, cellulitis, myositis, or necrotizing fasciitis) associated with severe increasing pain is common, but streptococcal TSS can occur without an identifiable focus of infection. Streptococcal TSS also can be associated with invasive infections, such as bacteremia, pneumonia, osteomyelitis, pyarthrosis, or endocarditis.

Table 3-69