How should I evaluate and manage an adult with sore throat, including indications for rapid streptococcal testing, appropriate antibiotic therapy (penicillin V, amoxicillin, cephalexin, azithromycin) for patients with and without penicillin allergy, and symptomatic treatment?

Evaluation and Management of Adult Sore Throat

Risk Stratification and Testing Strategy

Use the Centor criteria to determine who needs testing: award one point each for fever, tonsillar exudates, tender anterior cervical lymphadenopathy, and absence of cough. 1

• 0-1 criteria: No testing needed—viral etiology is most likely. Provide symptomatic treatment only. 1
• 2 criteria: Consider rapid antigen detection test (RADT) or throat culture. 1
• 3-4 criteria: Perform RADT before prescribing antibiotics. 1, 2

Do not test patients with clear viral features (cough, rhinorrhea, hoarseness, conjunctivitis, or diarrhea), as these strongly indicate viral pharyngitis and testing will only identify harmless carriers. 3, 1

The presence of cough is particularly important—it strongly favors a viral etiology and, combined with a negative rapid strep test, effectively excludes Group A streptococcal pharyngitis. 3

Diagnostic Testing Approach

In adults, a negative RADT alone is sufficient to rule out streptococcal pharyngitis—no backup throat culture is needed. 3, 2 The specificity of RADT is ≥95%, making false positives rare, while sensitivity is 80-90%. 3 Adults have only 5-10% prevalence of Group A streptococcal pharyngitis and extremely low risk of acute rheumatic fever, making the modest false-negative rate acceptable. 3

Throat culture is not necessary for routine diagnosis but can be used as an alternative to RADT if preferred. 2, 1

Do not routinely use biomarkers such as C-reactive protein or procalcitonin in the assessment of acute sore throat. 2, 1

Antibiotic Therapy for Confirmed Streptococcal Pharyngitis

First-Line Treatment (Non-Allergic Patients)

Penicillin V or amoxicillin for 10 days is the definitive first-line regimen, offering narrow-spectrum activity, low adverse-effect rates, and proven efficacy in preventing acute rheumatic fever. 3, 4

• Penicillin V: 500 mg orally 2-3 times daily for 10 days 3, 4
• Amoxicillin: 50 mg/kg once daily (maximum 1 g) for 10 days—equally effective and more palatable 3, 4
• Benzathine penicillin G (IM): Single dose of 1.2 million units for adherence concerns 3, 5

Penicillin-Allergic Patients

For non-anaphylactic penicillin allergy: Use a first-generation cephalosporin (e.g., cephalexin) for 10 days. 3, 5, 4

For anaphylactic or immediate-type hypersensitivity to penicillin:

• Clindamycin: 20 mg/kg/day divided three times daily (maximum 1.8 g/day) for 10 days 3
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 3, 6
• Clarithromycin: 15 mg/kg/day divided twice daily for 10 days 3

Note that azithromycin causes significantly more gastrointestinal side effects (16.6%) compared to penicillin (1.7%), though discontinuation rates are similar. 6

Symptomatic Treatment

Offer all patients analgesic therapy regardless of whether antibiotics are prescribed. 2

• Ibuprofen or acetaminophen are recommended as first-line analgesics for pain and fever relief. 2, 3
• Throat lozenges can provide additional comfort. 2, 3
• Salt water gargles and viscous lidocaine are often used but have limited supporting data. 2

Reassure patients that typical sore throat duration is less than 1 week. 2 Antibiotics only shorten symptom duration by 1-2 days, with a number needed to treat of 6 at day 3 and 21 at 1 week. 2, 5 The primary justification for treating confirmed streptococcal pharyngitis is prevention of acute rheumatic fever, peritonsillar abscess, and spread during outbreaks—not symptom relief. 3

Critical Pitfalls to Avoid

Never prescribe antibiotics based on clinical appearance alone without laboratory confirmation. 3, 1 White patches and exudates occur with both viral and bacterial infections and cannot reliably distinguish between them. 3 Even with a Centor score of 4, the positive predictive value is only 40-60%, meaning 40-60% would receive unnecessary antibiotics without testing. 3

Do not test or treat asymptomatic household contacts. 3 Up to one-third of household members may be asymptomatic Group A Streptococcus carriers, and prophylactic treatment does not reduce subsequent infection rates. 3

Do not perform routine follow-up testing after completing appropriate antibiotic therapy in asymptomatic patients. 3 A positive post-treatment test often reflects carrier status rather than treatment failure. 3

Red Flags Requiring Urgent Evaluation

Immediately evaluate for life-threatening conditions if the patient presents with:

• Difficulty swallowing, drooling, or neck swelling (suggests peritonsillar abscess, parapharyngeal abscess, or epiglottitis) 1
• Severe unilateral throat pain with trismus and uvular deviation (indicates peritonsillar abscess) 1
• Persistent fever with neck pain in adolescents/young adults with severe pharyngitis (consider Lemierre syndrome) 1