Treatment of Streptococcal Infections
First-Line Treatment for Non-Allergic Patients
For patients without penicillin allergy, penicillin V or amoxicillin for 10 days remains the treatment of choice for streptococcal pharyngitis. 1
- Penicillin V: 500 mg orally twice daily for adults; 250 mg twice daily for children 1
- Amoxicillin: 500 mg orally twice daily or 250 mg three times daily for adults; 25 mg/kg/day divided twice daily or 20 mg/kg/day divided three times daily for children weighing <40 kg 2
- Intramuscular benzathine penicillin G: 600,000 units for patients <27 kg; 1,200,000 units for patients ≥27 kg (single dose) - particularly useful when compliance is questionable 3, 1
The 10-day duration is essential to achieve maximal pharyngeal eradication and prevent acute rheumatic fever 1, 2. Penicillin has proven efficacy, narrow spectrum, safety, low cost, and no documented resistance in Group A Streptococcus anywhere in the world 4, 1.
Treatment for Penicillin-Allergic Patients
Determining Allergy Type
The type of penicillin allergy dictates which alternatives are safe. 4
- Non-immediate reactions (delayed rash, mild GI upset occurring >1 hour after administration): Cross-reactivity with first-generation cephalosporins is only 0.1% 4, 1
- Immediate/anaphylactic reactions (anaphylaxis, angioedema, respiratory distress, urticaria within 1 hour): Must avoid all beta-lactam antibiotics including cephalosporins due to up to 10% cross-reactivity risk 4, 1
For Non-Immediate Penicillin Allergy
First-generation cephalosporins are the preferred first-line alternatives with strong, high-quality evidence. 4, 1
- Cephalexin: 500 mg orally twice daily for 10 days (adults); 20 mg/kg per dose twice daily for 10 days (children, maximum 500 mg/dose) 4, 1
- Cefadroxil: 1 gram orally once daily for 10 days (adults); 30 mg/kg once daily for 10 days (children, maximum 1 gram) 4, 1
These agents have narrow spectrum, proven efficacy comparable to penicillin, and low cost 4, 1. Avoid broad-spectrum cephalosporins (cefdinir, cefixime, cefpodoxime) when narrow-spectrum agents are appropriate, as they are more expensive and select for resistant flora 4.
For Immediate/Anaphylactic Penicillin Allergy
Clindamycin is the preferred choice with strong, moderate-quality evidence. 4, 1
- Clindamycin: 300 mg orally three times daily for 10 days (adults); 7 mg/kg per dose three times daily for 10 days (children, maximum 300 mg/dose) 3, 4, 1
Clindamycin has approximately 1% resistance among Group A Streptococcus in the United States, making it highly reliable 4, 1. It demonstrates superior efficacy in chronic carriers and recurrent infections 4, 5.
Alternative macrolides (use only when clindamycin cannot be used):
- Azithromycin: 500 mg orally once daily for 5 days (adults); 12 mg/kg once daily for 5 days (children, maximum 500 mg) 4, 1
- Clarithromycin: 250 mg orally twice daily for 10 days (adults); 7.5 mg/kg per dose twice daily for 10 days (children, maximum 250 mg/dose) 4, 1
Macrolide resistance is 5-8% in the United States and varies geographically 4, 1. Azithromycin requires only 5 days due to prolonged tissue half-life, but all other antibiotics require the full 10-day course 4, 1.
Critical Treatment Duration Requirements
A full 10-day course is essential for all antibiotics except azithromycin to prevent acute rheumatic fever and achieve maximal bacterial eradication. 1, 2
- Shortening the course by even a few days results in appreciable increases in treatment failure rates 4, 1
- Azithromycin is the only exception, requiring 5 days due to unique pharmacokinetics 4, 1
- Treatment must be sufficient to eliminate the organism; otherwise sequelae of streptococcal disease may occur 6
Adjunctive Therapy
Symptomatic relief should be provided with analgesics/antipyretics. 1
- Acetaminophen or NSAIDs (ibuprofen): Recommended for moderate to severe symptoms or high fever 4, 1
- Aspirin: Must be avoided in children due to Reye syndrome risk 4, 1
- Corticosteroids: Not recommended 4, 1
Special Considerations
Chronic Carriers
Chronic carriers generally do not require treatment, as they are unlikely to spread infection or develop complications 3, 1. However, treatment may be indicated in special circumstances: community outbreaks of acute rheumatic fever, family history of rheumatic fever, or excessive family anxiety 3.
For chronic carriers requiring treatment, clindamycin demonstrates the highest eradication rates 3, 4.
Recurrent Infections
Patients with multiple episodes may be chronic carriers experiencing intercurrent viral infections rather than true recurrent streptococcal infections 3, 5. Helpful clues include patient age, season, local epidemiology, and precise nature of symptoms 3.
Post-Treatment Testing
Routine follow-up throat cultures are not recommended for asymptomatic patients who have completed therapy 4, 1. Testing should only be considered in special circumstances, such as patients with a history of rheumatic fever 4, 1.
Common Pitfalls to Avoid
- Do not use cephalosporins in patients with immediate/anaphylactic penicillin reactions due to 10% cross-reactivity risk 4, 1
- Do not prescribe azithromycin as first-line therapy - reserve for penicillin-allergic patients who cannot use preferred alternatives 4
- Do not ignore local macrolide resistance patterns - resistance varies geographically and can lead to treatment failure 4, 1
- Do not shorten antibiotic courses below 10 days (except azithromycin's 5-day regimen) - this dramatically increases treatment failure and rheumatic fever risk 4, 1
- Do not prescribe broad-spectrum cephalosporins when narrow-spectrum first-generation agents are appropriate 4
Clinical Response Timeline
Patients typically experience noticeable improvement within 24-48 hours of starting antibiotics and are no longer contagious after 24 hours of appropriate therapy 1. Symptoms resolve within less than 1 week even without antibiotics, but antibiotics shorten duration by approximately 1-2 days 1.