What is the recommended treatment for streptococcal (strep) infections in adults?

Treatment of Streptococcal Infections in Adults

Penicillin remains the first-line treatment for streptococcal pharyngitis in adults due to its proven efficacy, safety, narrow spectrum, and low cost. 1

First-Line Treatment Options

For Non-Penicillin Allergic Patients:

• Oral Penicillin V: 250 mg four times daily OR 500 mg twice daily for 10 days 1
• Amoxicillin: 500 mg twice daily for 10 days OR 50 mg/kg once daily (maximum 1,000 mg) for 10 days 1, 2
• Intramuscular Benzathine Penicillin G: 1.2 million units as a single dose (preferred for patients unlikely to complete a full oral course) 1

For Penicillin-Allergic Patients:

• Without immediate hypersensitivity to β-lactams:

  • First-generation cephalosporins (e.g., Cephalexin: 20 mg/kg twice daily, maximum 500 mg per dose, for 10 days) 1
  • Second-generation cephalosporins (e.g., Cefadroxil: 30 mg/kg once daily, maximum 1 g, for 10 days) 1

• With immediate hypersensitivity to β-lactams:

  • Clindamycin: 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days 1
  • Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days (note: resistance is well-known and varies geographically) 1, 3
  • Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg per dose) for 10 days 1

Treatment Duration

• A full 10-day course of therapy is essential for most antibiotics to achieve maximal pharyngeal eradication of group A streptococci and prevent acute rheumatic fever 1
• Exceptions include azithromycin (5 days) due to its prolonged tissue half-life 1, 3, 4
• Patients are generally considered non-contagious after 24 hours of antibiotic therapy 2

Efficacy Considerations

• Once-daily amoxicillin has been shown to be as effective as penicillin V given three times daily for treatment of streptococcal pharyngitis 5
• Twice-daily penicillin V (500 mg) has demonstrated similar cure rates to three-times-daily regimens (250 mg) 6
• While shorter courses (≤5 days) of certain antibiotics like azithromycin have shown comparable bacteriologic and clinical cure rates, definitive results from comprehensive studies are limited 1

Important Caveats and Considerations

• Tetracyclines, sulfonamides, and fluoroquinolones should not be used for treatment of streptococcal pharyngitis due to high resistance rates 1
• For penicillin V, the oral route should not be relied upon in patients with severe illness, nausea, vomiting, gastric dilatation, cardiospasm, or intestinal hypermotility 7
• Cultures should be taken following completion of treatment in certain cases to determine whether streptococci have been eradicated 7
• Routine testing or treatment of asymptomatic household contacts is not recommended unless there are special circumstances requiring repeated testing 1
• When treating with penicillin, a full 10-day course must be completed to prevent rheumatic fever, even if symptoms resolve earlier 7

Monitoring and Follow-Up

• Follow-up post-treatment throat cultures or rapid antigen detection tests are not routinely recommended but may be considered in special circumstances 1
• Patients should be counseled that although they may feel better early in the course of therapy, the full course of antibiotics must be completed to prevent complications and reduce the likelihood of bacterial resistance 7