What is the recommended treatment for a positive strep (streptococcal) infection?

Treatment of Streptococcal Pharyngitis

Penicillin V or amoxicillin are the first-line treatments for streptococcal pharyngitis due to their proven efficacy, safety, narrow spectrum, and low cost, with no documented penicillin resistance worldwide. 1, 2

First-Line Antibiotic Regimens

Oral Penicillin V (Preferred)

• Children: 250 mg twice or three times daily for 10 days 1, 2
• Adolescents and adults: 250 mg four times daily OR 500 mg twice daily for 10 days 1, 2
• Penicillin remains the treatment of choice because no clinical isolate of group A Streptococcus has ever been documented to be resistant to penicillin anywhere in the world 1
• The 10-day duration is essential to ensure complete eradication and prevent rheumatic fever 1, 2, 3

Oral Amoxicillin (Equally Effective Alternative)

• Children: 50 mg/kg once daily (maximum 1,000 mg) OR 25 mg/kg twice daily (maximum 500 mg) for 10 days 2
• Adults: 500 mg three times daily for 10 days 4
• Amoxicillin is often preferred for young children due to better palatability of the suspension 1
• Once-daily amoxicillin has been shown to be as effective as multiple-daily-dose penicillin V, with bacteriologic failure rates of 5% vs 11% respectively 5
• Higher-dose amoxicillin (40 mg/kg/day) achieves superior clinical cure (87.9% vs 70.9%) and bacteriologic cure (79.3% vs 54.5%) compared to standard-dose penicillin V 6

Intramuscular Benzathine Penicillin G

• Single dose: 600,000 units for patients <60 lb (27 kg); 1,200,000 units for patients ≥60 lb 2
• Reserved for patients unlikely to complete a full 10-day oral course due to compliance concerns 1, 2, 4

Penicillin-Allergic Patients

For Non-Immediate Hypersensitivity

• First-generation cephalosporins are acceptable alternatives 1, 4
• Cephalosporins should NOT be used in patients with immediate-type (anaphylactic) hypersensitivity to β-lactams 1

For True Penicillin Allergy

• Erythromycin is a suitable alternative, though <5% of U.S. group A streptococci isolates show resistance 1, 4
• Clindamycin 300 mg four times daily for 10 days is appropriate for erythromycin-resistant strains in patients who cannot tolerate β-lactams 1, 4
• Azithromycin 500 mg once daily for 3-5 days is FDA-approved for shorter courses 1, 4, 7

Critical caveat: Azithromycin should not be relied upon as first-line therapy because some strains are resistant, and data establishing efficacy in preventing rheumatic fever are not available 7. Susceptibility testing should be performed when using azithromycin 7.

Duration of Therapy: A Critical Decision Point

Most oral antibiotics must be administered for 10 days to achieve maximal pharyngeal eradication of group A streptococci. 1

• Short-course penicillin (<7 days) is significantly less effective than standard 10-day courses for both clinical cure (OR 0.43) and bacteriologic eradication (OR 0.34) 8
• Short-course cephalosporins (5 days) show superior efficacy compared to long-course penicillin, but cephalosporins are "Highest Priority Critically Important Antimicrobials" and should be reserved for penicillin-allergic patients 8
• Long-course penicillin V should remain first-line therapy as the benefits of shorter courses with broader-spectrum agents do not outweigh the harms of unnecessary use 8

Post-Treatment Management

When NOT to Retest

• Routine post-treatment testing is NOT recommended for asymptomatic patients who completed a full antibiotic course 1, 2, 9, 4
• Up to 20% of school-aged children are asymptomatic carriers during winter/spring, and carriers are at low risk for complications 9, 10

When to Consider Retreatment

• Only retest if symptoms persist or recur after completing therapy 9
• For treatment failures with persistent symptoms, consider retreatment with clindamycin, a narrow-spectrum cephalosporin, or amoxicillin-clavulanate 9
• Possible causes of persistent symptoms include: treatment failure, poor compliance, new infection with different strain, carrier state with concurrent viral infection, or macrolide resistance 9

Household Contacts

• Do NOT routinely test or treat asymptomatic household contacts 1, 4
• Only test family members if the patient has multiple episodes within a short period, then treat those with positive cultures 9, 4

Common Pitfalls to Avoid

• Do NOT use antibiotics for viral pharyngitis presenting with cough, rhinorrhea, hoarseness, or oral ulcers 2
• Do NOT use tetracyclines, sulfonamides, or trimethoprim-sulfamethoxazole as they are ineffective against group A Streptococcus 1, 9
• Do NOT interpret positive post-treatment tests as treatment failure when the patient is asymptomatic—this likely represents carrier state 9
• Do NOT use aspirin in children due to risk of Reye syndrome; use acetaminophen or NSAIDs instead 2