What is the recommended treatment for an otherwise healthy adult or child with a positive rapid antigen test or throat culture for streptococcal pharyngitis?

Treatment for Strep Throat

Penicillin or amoxicillin for 10 days is the definitive first-line treatment for Group A streptococcal pharyngitis in otherwise healthy adults and children, based on proven efficacy in preventing rheumatic fever, lack of resistance, narrow spectrum, safety profile, and low cost. 1

First-Line Antibiotic Regimens

Oral Penicillin V

• Children: 250 mg twice daily or three times daily for 10 days 1
• Adolescents and adults: 250 mg four times daily OR 500 mg twice daily for 10 days 1
• Penicillin remains the gold standard because no Group A streptococcal isolate worldwide has ever demonstrated resistance 2

Oral Amoxicillin (Preferred in Young Children)

• Dosing: 50 mg/kg once daily (maximum 1000 mg) OR 25 mg/kg twice daily (maximum 500 mg) for 10 days 1
• Amoxicillin is often preferred in children due to better palatability and simpler once-daily dosing that improves adherence 2
• Clinical and bacteriologic cure rates are equivalent to or superior to penicillin V 3

Intramuscular Benzathine Penicillin G

• Dosing: <27 kg: 600,000 units; ≥27 kg: 1,200,000 units as a single injection 1
• This is the preferred option when compliance with oral therapy is questionable, as it ensures complete treatment and has historically been the gold standard for cure rates 1, 4

Treatment for Penicillin-Allergic Patients

Non-Immediate (Delayed) Hypersensitivity

• First-generation cephalosporins are recommended for patients without anaphylactic reactions 1, 2
• Cephalexin: 20 mg/kg/dose twice daily (maximum 500 mg/dose) for 10 days 1
• Cefadroxil: 30 mg/kg once daily (maximum 1 g) for 10 days 1
• Cross-reactivity risk with penicillin is <3% for non-immediate reactions 2

Immediate-Type or Anaphylactic Hypersensitivity

• Avoid all cephalosporins due to up to 10% cross-reactivity risk 2
• Clindamycin: 7 mg/kg/dose three times daily (maximum 300 mg/dose) for 10 days 1
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1
• Clarithromycin: 7.5 mg/kg/dose twice daily (maximum 250 mg/dose) for 10 days 1

Important caveat: Macrolide resistance varies geographically and temporally, so local resistance patterns should be considered 1. The FDA label for azithromycin explicitly states that susceptibility testing should be performed and that data establishing efficacy in preventing rheumatic fever are not available 5.

Critical Treatment Duration

A full 10-day course is mandatory for all oral antibiotics except azithromycin (5 days) to achieve maximal pharyngeal eradication and prevent acute rheumatic fever. 1, 2

• Therapy can be safely delayed up to 9 days after symptom onset and still prevent rheumatic fever 2
• Shorter courses dramatically increase treatment failure rates and risk of complications 2
• Azithromycin requires only 5 days due to its prolonged tissue half-life 1

Primary Treatment Goals

Treatment achieves multiple critical outcomes beyond symptom relief:

• Prevention of acute rheumatic fever (the most important outcome) 1, 2
• Prevention of suppurative complications including peritonsillar abscess, cervical lymphadenitis, and mastoiditis 1
• Rapid symptom resolution (typically within 24 hours of starting antibiotics) 4
• Decreased infectivity after 24 hours of appropriate therapy 2
• Reduced transmission to close contacts 2

Post-Treatment Management

Routine follow-up throat cultures or rapid antigen detection tests are NOT recommended for asymptomatic patients who have completed therapy 1, 2

Follow-up testing is only indicated in specific circumstances:

• Patients who remain symptomatic or have recurrent symptoms 1
• Patients with a personal history of rheumatic fever 1
• During outbreaks of acute rheumatic fever or post-streptococcal glomerulonephritis 2

Management of Treatment Failure or Recurrent Infections

For patients with persistent or recurrent symptoms and positive cultures after completing initial therapy:

Single Recurrence

• Retreat with the same regimen OR switch to an alternative oral agent 1
• Consider intramuscular benzathine penicillin G if compliance is questionable 1

Multiple Recurrent Episodes

For patients with multiple documented episodes, use agents with higher eradication rates 1:

• Clindamycin: Children 20-30 mg/kg/day in 3 divided doses; Adults 600 mg/day in 2-4 divided doses for 10 days 1
• Amoxicillin-clavulanate: 40 mg/kg/day (amoxicillin component) in 3 divided doses for 10 days (maximum 750 mg/day) 1
• Benzathine penicillin G with or without rifampin (20 mg/kg/day in 2 divided doses for 4 days) 1

Important distinction: Many patients with recurrent positive cultures are chronic carriers experiencing intercurrent viral infections rather than true treatment failures 1. Carriers are at very low risk for rheumatic fever and generally do not require treatment unless they have a personal or family history of rheumatic fever 1.

Common Pitfalls to Avoid

• Never use tetracyclines, sulfonamides, trimethoprim-sulfamethoxazole, or older fluoroquinolones (e.g., ciprofloxacin) as they are not effective against Group A streptococci 1
• Do not shorten the antibiotic course below 10 days for oral beta-lactams, despite some literature suggesting shorter courses may work 2
• Do not prescribe cephalosporins to patients with immediate/anaphylactic penicillin allergy due to cross-reactivity risk 2
• Do not routinely test or treat asymptomatic household contacts unless there are special circumstances 1
• Do not perform routine post-treatment cultures in asymptomatic patients who completed therapy 1