What is the recommended antibiotic treatment for strep throat in adults?

Antibiotic Treatment for Strep Throat in Adults

Penicillin V 500 mg twice daily or 250 mg four times daily for 10 days is the first-line treatment for streptococcal pharyngitis in adults, with amoxicillin 500 mg twice daily for 10 days as an equally effective and more convenient alternative. 1, 2

First-Line Treatment Options

For adults without penicillin allergy:

• Penicillin V remains the drug of choice due to its proven efficacy, narrow spectrum of activity, safety profile, and low cost 1, 2
• Dosing: 250 mg four times daily OR 500 mg twice daily for 10 days 1, 2
• Amoxicillin is an equally effective alternative with better palatability and simpler dosing: 500 mg twice daily for 10 days 1, 2, 3
• The full 10-day course is essential to prevent acute rheumatic fever and other complications, even if symptoms resolve earlier 2, 3

For patients unlikely to complete oral therapy:

• Intramuscular benzathine penicillin G 1.2 million units as a single dose is preferred when adherence is a concern 1, 2, 4
• This ensures complete treatment and eliminates compliance issues 1, 5

Treatment for Penicillin-Allergic Patients

The choice depends on the type of allergy:

For non-immediate (non-IgE mediated) penicillin allergy:

• First-generation cephalosporins are recommended 1
• Cephalexin 500 mg twice daily for 10 days (strong, high-quality evidence) 1, 2
• Cefadroxil 1 g once daily for 10 days 1, 2

For immediate-type hypersensitivity (anaphylaxis, urticaria):

• Avoid all beta-lactams including cephalosporins 1
• Clindamycin 300 mg three times daily for 10 days (strong, moderate-quality evidence) 1, 2, 4
• Azithromycin 500 mg on day 1, then 250 mg daily for days 2-5 (strong, moderate-quality evidence) 1, 2
• Clarithromycin 250 mg twice daily for 10 days 1, 2

Critical Caveats and Pitfalls

Macrolide resistance considerations:

• Geographic variation in macrolide resistance is significant and should influence antibiotic selection 1, 2
• Resistance rates vary from 5-8% in the United States but can be higher in other regions 4
• When macrolides are used, be aware that treatment failure may occur due to resistance 1

Clinical response timeline:

• Patients become non-contagious after 24 hours of appropriate antibiotic therapy 2, 3
• Symptoms typically improve within 24 hours of treatment initiation 5
• Do not routinely perform follow-up cultures after treatment completion unless symptoms persist 2

What NOT to use:

• Sulfonamides and tetracyclines should not be used due to high resistance rates 4
• Shorter courses of newer antibiotics (less than 10 days) are not currently endorsed despite some studies suggesting efficacy, as comprehensive evidence is insufficient 1, 2

Treatment Goals and Rationale

Antibiotic therapy achieves multiple objectives:

• Prevention of acute rheumatic fever (the primary goal) 1
• Prevention of suppurative complications (peritonsillar abscess, cervical lymphadenitis, mastoiditis) 1
• Symptom improvement and fever reduction 1
• Rapid decrease in contagiousness and transmission to close contacts 1
• Earlier return to usual activities 1

Special Populations

Chronic carriers:

• Do not routinely treat asymptomatic carriers as they are at low risk for complications and unlikely to spread infection 1, 4
• Treatment may be considered during outbreaks or in patients with personal/family history of rheumatic fever 1
• Do not routinely culture or treat asymptomatic household contacts 1, 4