Diagnosis and Treatment of Suspected Bacterial Pharyngitis
For suspected bacterial pharyngitis, confirm the diagnosis with a rapid antigen detection test (RADT) or throat culture before prescribing antibiotics, then treat with penicillin or amoxicillin for 10 days as first-line therapy. 1
Testing Recommendations
When to Test
- Perform RADT or throat culture in patients with clinical features suggesting Group A Streptococcus (GAS), including sudden onset sore throat, fever, tonsillar exudate, tender anterior cervical lymphadenopathy, and absence of cough 1, 2
- Do NOT test patients with features strongly suggesting viral etiology (cough, rhinorrhea, hoarseness, oral ulcers, conjunctivitis) 1, 2
- Do NOT test children under 3 years old, as acute rheumatic fever is rare in this age group and streptococcal pharyngitis is uncommon 1
Testing Algorithm
- In children and adolescents: If RADT is negative, back it up with a throat culture 2
- In adults: RADT alone is generally sufficient; negative results do not require culture confirmation 2
- Avoid testing asymptomatic household contacts, as this is not recommended 1, 3
First-Line Treatment
For Non-Penicillin Allergic Patients
Penicillin or amoxicillin remains the treatment of choice based on narrow spectrum, proven efficacy, safety, and low cost 1, 2
Dosing options:
- Penicillin V oral: 250 mg twice or three times daily for 10 days (children); 250 mg three to four times daily or 500 mg twice daily for 10 days (adolescents/adults) 2
- Amoxicillin oral: 50 mg/kg once daily (maximum 1000 mg) for 10 days, OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1, 2, 4
- Benzathine penicillin G intramuscular: <27 kg: 600,000 units; ≥27 kg: 1,200,000 units as a single dose 1
Key point: Amoxicillin is often preferred in young children due to better taste acceptance and the option for once-daily dosing, which may improve adherence 1, 2
For Penicillin-Allergic Patients
Non-anaphylactic allergy:
Anaphylactic allergy (avoid cephalosporins):
- Clindamycin: 7 mg/kg/dose three times daily (maximum 300 mg/dose) for 10 days 1
- Clarithromycin: 7.5 mg/kg/dose twice daily (maximum 250 mg/dose) for 10 days 1
- Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1
Critical caveat: Macrolide resistance (azithromycin, clarithromycin) varies geographically and temporally; avoid in areas with high resistance rates 1, 2, 5
Treatment Duration
The full 10-day course is essential for penicillin or amoxicillin to prevent acute rheumatic fever, even if symptoms resolve earlier 1, 2, 4. Failure to complete the full course increases risk of treatment failure and rheumatic fever 2.
Adjunctive Therapy
- NSAIDs or acetaminophen for moderate to severe symptoms or fever control 1, 2
- Avoid aspirin in children due to Reye syndrome risk 1
- Corticosteroids are NOT recommended for routine use 1, 2
Common Pitfalls to Avoid
- Overdiagnosis of viral pharyngitis as bacterial: Most pharyngitis (70-85%) is viral; confirm with testing before treating 2, 6
- Empiric treatment without testing: Always confirm diagnosis with RADT or culture except in specific high-risk scenarios 1, 2
- Incomplete antibiotic course: Emphasize the need for full 10-day treatment to prevent rheumatic fever 2, 4
- Testing asymptomatic contacts: This wastes resources and promotes resistance without clinical benefit 1, 3
- Using macrolides in high-resistance areas: Check local resistance patterns before prescribing azithromycin or clarithromycin 1, 2
- Once-daily penicillin V: This has higher failure rates compared to divided dosing 7
Special Considerations
Intramuscular benzathine penicillin G is preferred when compliance with oral therapy is uncertain, particularly in populations where rheumatic fever remains prevalent or follow-up is unreliable 1, 2