In a patient with acute sore throat, fever, tonsillar exudates, tender anterior cervical lymphadenopathy and no cough, how should I evaluate and treat possible group A streptococcus (GAS) pharyngitis?

Evaluation and Treatment of Suspected Group A Streptococcal Pharyngitis

In a patient presenting with acute sore throat, fever, tonsillar exudates, tender anterior cervical lymphadenopathy, and no cough, you should perform a rapid antigen detection test (RADT) and treat with penicillin or amoxicillin for 10 days if positive. 1

Diagnostic Approach

Your patient has 4 out of 4 Centor criteria (fever, tonsillar exudates, tender anterior cervical lymphadenopathy, absence of cough), which substantially increases the pre-test probability of GAS pharyngitis but still requires microbiologic confirmation before prescribing antibiotics. 1, 2

Testing Strategy

• Perform a rapid antigen detection test (RADT) immediately—this is the first-line diagnostic test with ≥95% specificity, making false positives rare. 1, 3

• If RADT is positive: No backup throat culture is needed; proceed directly to antibiotic therapy. 1, 4

• If RADT is negative in adults: A single negative RADT is sufficient to rule out GAS pharyngitis; do not order a backup throat culture. 1, 3

• If RADT is negative in children/adolescents: You must obtain a backup throat culture because RADT sensitivity is only 80-90% in this age group, missing 10-20% of true infections. 1, 3

The absence of cough is a critical distinguishing feature—cough strongly favors viral etiology and its absence supports bacterial pharyngitis. 1, 3

First-Line Antibiotic Treatment (When RADT Positive)

Penicillin or amoxicillin for 10 days is the definitive first-line regimen based on narrow spectrum, proven efficacy in preventing acute rheumatic fever, safety profile, and low cost. 1

Specific Dosing Regimens

For non-penicillin-allergic patients:

• Penicillin V: 250 mg 3-4 times daily OR 500 mg twice daily for 10 days (adults); 250 mg 2-3 times daily for children <27 kg. 1, 4

• Amoxicillin: 50 mg/kg once daily (maximum 1000 mg) for 10 days—this may enhance adherence due to once-daily dosing. 1, 4

• Benzathine penicillin G (IM): Single dose of 600,000 U for patients <27 kg; 1,200,000 U for patients ≥27 kg—reserved for adherence concerns. 1

For penicillin-allergic patients (non-anaphylactic):

• First-generation cephalosporin (e.g., cephalexin 20 mg/kg/dose twice daily, maximum 500 mg/dose) for 10 days. 1, 4

For penicillin-allergic patients (anaphylactic/immediate hypersensitivity):

• Clindamycin: 20-30 mg/kg/day divided in 3 doses (maximum 300 mg/dose) for 10 days. 1, 4

• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days. 1, 4

• Clarithromycin: 7.5 mg/kg/dose twice daily (maximum 250 mg/dose) for 10 days. 1

Critical Duration Point

A full 10-day course is mandatory for penicillin, amoxicillin, cephalosporins, clindamycin, and clarithromycin—only azithromycin has evidence supporting a 5-day regimen due to its unique pharmacokinetics. 1, 5 Treatment initiated up to 9 days after symptom onset still effectively prevents acute rheumatic fever. 3

Adjunctive Symptomatic Management

• Acetaminophen or NSAIDs (e.g., ibuprofen) should be offered for moderate to severe symptoms or high fever as an adjunct to antibiotics. 1, 3

• Avoid aspirin in children due to the risk of Reye syndrome. 1

• Corticosteroids are not recommended as adjunctive therapy for GAS pharyngitis. 1

• Throat lozenges and warm salt water gargles may provide temporary symptomatic relief. 1, 3

Management When RADT is Negative

Do not prescribe antibiotics when GAS testing is negative—the vast majority of these cases are viral and self-limited, and antibiotics offer no clinical benefit. 1, 3, 4 Provide only symptomatic treatment with analgesics/antipyretics. 1, 3

Critical Pitfalls to Avoid

• Never prescribe antibiotics based on clinical appearance alone without laboratory confirmation—even with 4/4 Centor criteria, the positive predictive value is only 40-60%, meaning 40-60% would receive unnecessary antibiotics. 1, 3

• Do not use amoxicillin-clavulanate as first-line therapy—the clavulanate component adds unnecessary cost, broader spectrum activity, and increased gastrointestinal side effects without improving efficacy for uncomplicated GAS pharyngitis. 5

• Do not prescribe shorter courses (<10 days) of penicillin or amoxicillin—this increases the risk of treatment failure and inadequate prevention of rheumatic fever. 4, 5

• Do not test or treat asymptomatic household contacts—up to one-third may be asymptomatic GAS carriers, and prophylactic treatment does not reduce subsequent infection rates. 1, 3

• Do not order routine post-treatment throat cultures or RADTs in asymptomatic patients—positive tests after appropriate treatment likely reflect carrier status rather than treatment failure. 1

Special Considerations for Recurrent Episodes

If the patient presents with recurrent pharyngitis episodes with positive GAS tests at close intervals, consider that they may be a chronic pharyngeal GAS carrier experiencing repeated viral infections rather than true recurrent GAS infections. 1 Chronic carriers do not ordinarily require antimicrobial therapy because they are unlikely to spread GAS to close contacts and are at little to no risk for developing suppurative or nonsuppurative complications. 1