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JAAPA Journal of the American Academy of Physician Assistants www.JAAPA.com 53

SPECIAL TOPICS IN INFECTIOUS DIS EASES

Acute pharyngitis, or sore throat, is one of the mostcommon infections encountered in primary care. Mostacute pharyngitis is caused by respiratory viruses, butseveral species of bacteria also cause acute pharyngitis. Amongthe bacterial species, Group A beta-hemolytic Streptococcus (GAS) is the most common bacterial pathogen. In children,GAS accounts for 15% to 30% of acute pharyngitis andoccurs most frequently in children ages 5 to 15 years, primar-ily during winter and early spring. In adults, GAS accountsfor 5% to 10% of acute pharyngitis. 1 GAS pharyngitis istypically a self-limiting illness, but can result in suppurativecomplications, such as peritonsillar abscess or mastoiditis,and non-suppurative complications, such as acute rheumaticfever, rheumatic heart disease, and post-streptococcal glo-merulonephritis. These complications largely can be preventedwith appropriate antibacterial therapy. Antibacterial treatmentalso can decrease the duration of symptoms and reduce therate of transmission. Therefore, distinguishing between viralpharyngitis and GAS pharyngitis is key. 2 Unfortunately, theclinical presentations of viral and GAS pharyngitis haveoverlapping signs and symptoms, such that no single elementof the history or physical examination accurately excludesor diagnoses GAS pharyngitis. 3 Clinical judgment alone resultsin an 80% to 95% overestimate of the disease, and conse-quently, an overprescribing of antibiotics. 4

The symptoms of GAS pharyngitis include sudden-onsetsore throat, pain with swallowing, and fever. Children mayhave headache, nausea, vomiting, and abdominal pain.

Physical examination reveals erythematous tonsillopharyn-geal mucosa with or without exudates, and lymphadenitiswith tender and enlarged anterior cervical lymph nodes.Other ndings can include erythematous (beefy red) uvula,hard palate petechiae, scarlatiniform rash, and excoriatednares, especially in infants. 1 Exposure to GAS within 2 weeksbefore the onset of symptoms also suggests GAS pharyngi-tis. These classical clinical presentations are observed in only20% to 30% of patients with GAS pharyngitis.

The absence of fever and presence of conjunctivitis, cough,coryza, stomatitis, conjunctivitis, diarrhea, hoarseness, andulcerative oropharyngeal lesions strongly suggest viral phar-yngitis. Some patients experience recurrent bouts of GASpharyngitis shortly after resolution of initial disease. Othersmay experience a recurrence of pharyngitis symptoms, butmay be colonized with GAS of the oropharynx without actualGAS infection, and are actually experiencing viral pharyngitis. 2

The gold standard for diagnosing GAS pharyngitis is apositive throat swab culture on sheep-blood agar plate froma patient with suggestive clinical signs and symptoms. Asingle throat swab culture has high sensitivity (90% to 95%)for detecting GAS. The disadvantage of throat culture is thedelay in providing resultsan 18- to 24-hour incubationperiod at 35 to 37 C is needed before results can be deter-mined. Alternatively, the rapid antigen detection testing(RADT), which detects the group-specic cell wall carbo-hydrate antigen of GAS, can provide results in a matter ofminutes. Commercially available RADTs, using enzyme-linked immunosorbent assays or optical immunoassays, or

Diagnosis and management of groupA beta-hemolytic streptococcal pharyngitisRoy A. Borchardt, PA-C, PhD

Roy Borchardt is a PA in the department of infectious diseases,infection control, and employee health at the University of Texas M.D.Anderson Cancer Center in Houston, Texas, and department editorof Special Topics in .... The author has indicated no relationships todisclose relating to the content of this article.

DOI: 10.1097/01.JAA.0000433876.39648.52

Copyright 2013 American Academy of Physician Assistants

ABSTRACTViral and Group A beta-hemolytic streptococcal (GAS)pharyngitis have overlapping signs and symptoms, but dis-tinguishing between the two is critical to proper treatment.Antibacterial therapy is appropriate for GAS pharyngitisand may help prevent complications.Keywords: Group A beta-hemolytic streptococcal pharyngi-tis, acute sore throat, lymphadenitis, antibiotics, penicillin

Key points

Group A beta-hemolytic Streptococcus (GAS) is the mostcommon bacterial cause of acute bacterial pharyngitis.

Diagnostic studies with RADT and/or throat culture canhelp distinguish between viral and GAS pharyngitis, andaid in the decision to initiate antibiotic therapy.Patients should be treated with an appropriate antibiotic

for a sufficient duration, typically 10 days, to eradicatethe disease and prevent complications. GAS pharyngitis is typically a self-limiting disease, so

shorter durations of antibiotic therapy may be efficaciousfor most patients, but this cannot be recommended untilfurther information on complication rates is available.

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