Diagnostic studies for GAS pharyngitis are not recommended for children under 3 because acute rheumatic fever is rare in children <3 years old and the incidence of strep pharyngitis and the classic presentation of strep pharyngitis are uncommon in this age group.

GAS as a cause of pharyngitis is most commonly observed in children 5–15 years of age.

Ed’s note: the IDSA says in this situation you can consider testing a 3 year old. If a child is <3 years of age and there is household contact with a school-aged sibling with documented streptococcal pharyngitis, then it is reasonable to consider testing the child if they are symptomatic.

Strep pharyngitis can lead to nonsuppurative post-infectious disorders such as acute rheumatic fever and poststreptococcal glomerulonephritis as well as suppurative complications like peritonsillar abscess, otitis media, bacteremia as in addition to meningitis.

Antimicrobial therapy is important for the prevention of acute rheumatic fever and for the prevention of suppurative complications. Treatment of pharyngitis does not affect the development of poststreptococcal glomerulonephritis.

There is a lot of overlap between the signs and symptoms of strep and non-strep (usually viral) pharyngitis. Testing for GAS should be considered in individuals that have evidence of pharyngitis (erythema or exudate) and absence of URI symptoms such as conjunctivitis, cough, and hoarseness. The Centor criteria is used to decide when to test for strep and not when to treat.

The Centor criteria consists of the following 1) absence of cough 2) tonsillar exudate 3) history of fever and 4) tender anterior cervical adenopathy.

Swabbing the throat and testing for GAS pharyngitis by rapid antigen detection test (RADT) and/or culture should be performed in individuals that meet the Centor criteria because clinical features alone do not reliably discriminate between GAS and viral pharyngitis.

RADTs currently available are highly specific (approximately 95%) and so treatment is recommended in the setting of a positive result. In children and adolescents, negative RADTs should be backed up by a throat culture .

Chronic pharyngeal carriers have GAS present in the pharynx but they do not have evidence of an active immunologic response to the organism. Individuals who are chronic GAS carriers do not ordinarily require further antibiotics. Carriers are unlikely to spread the organism to their close contacts and are at very low risk for developing suppurative and nonsuppurative complications.

There are special situations in which eradication of carriage may be desirable, including the following: (1) during a community outbreak of acute rheumatic fever and (2) during an outbreak of GAS pharyngitis in a closed or partially closed community.