What is the preferred treatment between amoxicillin (amox) and Augmentin (amoxicillin/clavulanate) for adult streptococcal pharyngitis (strep throat)?

Treatment of Adult Streptococcal Pharyngitis: Amoxicillin vs. Augmentin

Penicillin or amoxicillin is the preferred first-line treatment for adult streptococcal pharyngitis due to proven efficacy, safety, narrow spectrum, and low cost, while Augmentin (amoxicillin-clavulanate) should be reserved for specific situations where resistance is suspected. 1

First-Line Treatment Recommendation

Amoxicillin vs. Augmentin

• Preferred agent: Amoxicillin (without clavulanate)

  • Dosage: 500 mg twice daily for 10 days 1
  • Alternative: Once-daily amoxicillin (1000 mg) for 10 days has also shown effectiveness 1, 2

• Rationale for choosing amoxicillin over Augmentin:

  • Equal efficacy against Group A Streptococcus (GAS)
  • Narrower antimicrobial spectrum (reduces risk of resistance)
  • Lower cost
  • Fewer gastrointestinal side effects
  • GAS has never developed resistance to penicillin or amoxicillin 1

When to Consider Augmentin (Amoxicillin-Clavulanate)

Augmentin should be reserved for specific clinical scenarios:

1. Failure of initial therapy with amoxicillin 1
2. Recurrent streptococcal pharyngitis 3
3. Situations where bacterial resistance is likely:
   • Recent antibiotic use (within past month)
   • Close contact with treated individuals or healthcare environments
   • High prevalence of resistant bacteria in community 1

Treatment Algorithm

1. Confirm diagnosis with rapid antigen detection test (RADT) or throat culture

   • For adults with 2+ Centor criteria (fever, tonsillar exudates, no cough, tender anterior cervical lymphadenopathy) 3

2. For confirmed GAS pharyngitis:

   • First line: Amoxicillin 500 mg twice daily for 10 days
   • Alternative: Penicillin V 500 mg twice daily for 10 days 1

3. For penicillin-allergic patients:

   • Non-anaphylactic allergy: First-generation cephalosporin for 10 days
   • Anaphylactic allergy: Clindamycin (10 days), clarithromycin (10 days), or azithromycin (5 days) 1

4. For treatment failure with amoxicillin:

   • Consider Augmentin (amoxicillin-clavulanate) 1, 3
   • Alternative: Clindamycin 1

Important Clinical Considerations

• Duration: A full 10-day course is recommended for all oral beta-lactams (penicillin, amoxicillin) to ensure bacterial eradication and prevent complications like rheumatic fever 1

• Compliance: Once-daily amoxicillin may improve adherence compared to multiple daily doses of penicillin V 1, 2

• Avoid tetracyclines, sulfonamides, trimethoprim-sulfamethoxazole, and older fluoroquinolones as they are ineffective against GAS 1

• Adjunctive therapy: Acetaminophen or NSAIDs for symptom relief (avoid aspirin in children) 1

• No follow-up cultures are needed if symptoms resolve after treatment 1, 3

Common Pitfalls to Avoid

1. Using Augmentin as first-line therapy when simple amoxicillin would suffice

   • Broader spectrum increases risk of resistance and side effects
   • Higher cost without additional benefit for uncomplicated GAS

2. Prescribing shorter courses of penicillin/amoxicillin

   • The standard 10-day course is needed to prevent complications like rheumatic fever 1

3. Using macrolides as first-line therapy

   • Increasing resistance rates (5-8% in the US) 1
   • Higher cost and more side effects than penicillin/amoxicillin

4. Treating without confirmation of GAS infection

   • Viral pharyngitis is more common in adults and does not require antibiotics

By following these evidence-based recommendations, clinicians can effectively treat adult streptococcal pharyngitis while minimizing unnecessary broad-spectrum antibiotic use.