Treatment for Bacterial Pharyngitis
Penicillin or amoxicillin is the first-line treatment for Group A beta-hemolytic streptococcal (GABHS) pharyngitis due to proven efficacy, safety, narrow spectrum, low cost, and the absence of any documented penicillin resistance worldwide. 1, 2
First-Line Treatment Regimen
Penicillin V remains the drug of choice for GABHS pharyngitis, administered orally for 10 days 1, 2. The standard duration of 10 days is essential to achieve maximal pharyngeal eradication and prevent acute rheumatic fever 1, 2.
Amoxicillin is equally effective as penicillin and is often preferred for children due to better palatability of the suspension 1, 2. Once-daily amoxicillin (50 mg/kg/day, maximum 1000 mg) for 10 days has demonstrated effectiveness with improved adherence due to convenient dosing 2, 3.
Critical Point About Resistance
There has never been a documented case of penicillin-resistant Group A Streptococcus anywhere in the world 2. This makes penicillin and amoxicillin uniquely reliable for treating this infection.
Treatment Goals
The primary objectives of antibiotic therapy are 2, 4:
- Prevent acute rheumatic fever (the most critical outcome for morbidity)
- Prevent suppurative complications (peritonsillar abscess, cervical lymphadenitis)
- Decrease infectivity and transmission
- Hasten symptom resolution
Alternative Treatments for Penicillin-Allergic Patients
Non-Anaphylactic Penicillin Allergy
First-generation cephalosporins are the preferred alternatives for patients with non-immediate penicillin allergies 2, 5:
- Cephalexin: 20 mg/kg per dose twice daily (maximum 500 mg/dose) for 10 days 2, 5
- Cefadroxil: 30 mg/kg once daily (maximum 1 gram) for 10 days 2, 5
The cross-reactivity risk with first-generation cephalosporins is only 0.1% in patients with non-severe, delayed penicillin reactions 5.
Immediate/Anaphylactic Penicillin Allergy
Patients with immediate hypersensitivity must avoid all beta-lactam antibiotics due to up to 10% cross-reactivity risk 2, 5. Recommended alternatives include:
Clindamycin (preferred choice) 2, 5:
- Children: 20-30 mg/kg/day divided into 3 doses for 10 days
- Adults: 600 mg/day in 2-4 equally divided doses (or 300 mg three times daily) for 10 days
- Resistance rate: approximately 1% in the United States 2, 5
- Particularly effective in chronic carriers who have failed penicillin treatment 2, 5
Macrolides (acceptable alternatives with caveats) 2, 5:
- Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 2, 5, 6
- Clarithromycin: 7.5 mg/kg per dose twice daily (maximum 250 mg/dose) for 10 days 2, 5
- Erythromycin: 20-40 mg/kg/day divided 2-3 times daily for 10 days 2, 5
Important Caveat About Macrolides
Macrolide resistance among Group A Streptococcus is approximately 5-8% in the United States and varies geographically 2, 5. Clindamycin is more reliable than macrolides due to its lower resistance rate (1% vs 5-8%) 2, 5. Additionally, data establishing efficacy of azithromycin in preventing rheumatic fever are not available 6.
Critical Treatment Duration Requirements
All antibiotics except azithromycin require a full 10-day course to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever 1, 2, 5. Azithromycin is the only exception, requiring only 5 days due to its prolonged tissue half-life 2, 5, 6.
Shortening the course by even a few days results in appreciable increases in treatment failure rates and rheumatic fever risk 2, 5.
Treatment for Recurrent or Treatment-Failure Cases
For patients with recurrent culture-positive episodes or treatment failures 1:
- Clindamycin: Children 20-30 mg/(kg·d) for 10 days; Adults 600 mg/day in 2-4 divided doses for 10 days 1
- Amoxicillin/clavulanate: 40 mg/(kg·d) in 3 divided doses for 10 days (maximum 750 mg amoxicillin per day) 1
- Benzathine penicillin G: Useful for patients with questionable compliance 1
Common Pitfalls to Avoid
Do not use broad-spectrum antibiotics as first-line therapy (such as Augmentin or broad-spectrum cephalosporins) when narrow-spectrum options are appropriate, as this increases costs and promotes antimicrobial resistance without providing additional clinical benefit 2.
Do not use tetracyclines, sulfonamides, or trimethoprim-sulfamethoxazole due to high resistance rates 2.
Do not prescribe cephalosporins to patients with immediate/anaphylactic penicillin reactions due to the 10% cross-reactivity risk 2, 5.
Do not routinely perform post-treatment throat cultures for asymptomatic patients who have completed therapy 1, 2.
Do not test or treat asymptomatic household contacts routinely 1, 2.
Do not shorten treatment duration below 10 days (except for azithromycin's 5-day regimen), as this dramatically increases treatment failure and rheumatic fever risk 2, 5.
Post-Treatment Management
Routine follow-up cultures or rapid antigen detection tests are not recommended for asymptomatic patients who have completed an adequate course of antimicrobial therapy 1, 2. Testing should only be considered in special circumstances, such as patients with a history of rheumatic fever 2, 5.