What is the recommended treatment for an adult patient with strep throat?

Treatment for Strep Throat in Adults

For adults with confirmed strep throat, penicillin V 500 mg twice daily or amoxicillin 500 mg twice daily for 10 days is the first-line treatment, with first-generation cephalosporins (like cephalexin 500 mg twice daily for 10 days) for non-anaphylactic penicillin allergy, and clindamycin 300 mg three times daily for 10 days for immediate/anaphylactic penicillin allergy. 1, 2

Confirming the Diagnosis First

Before treating, adults should be tested only if they have clinical features suggesting bacterial pharyngitis rather than viral infection 1:

• Test patients with ≥2 Centor criteria: fever by history, tonsillar exudates, tender anterior cervical adenopathy, and absence of cough 1, 3
• Do not test or treat patients with viral features like cough, rhinorrhea, hoarseness, or oral ulcers 1
• Use rapid antigen detection test (RADT) in adults; backup throat culture is optional given the low incidence of acute rheumatic fever in adults 1

First-Line Treatment for Non-Allergic Patients

Penicillin or amoxicillin remains the drug of choice due to proven efficacy, narrow spectrum, no documented resistance, safety, and low cost 1, 2:

• Penicillin V: 500 mg orally twice daily for 10 days (or 250 mg four times daily) 1, 2
• Amoxicillin: 500 mg orally twice daily for 10 days (or 1000 mg once daily) 2, 4, 5
• Benzathine penicillin G: 1.2 million units intramuscularly as a single dose for patients unlikely to complete oral therapy 1, 2

The full 10-day course is mandatory to achieve maximal pharyngeal eradication and prevent acute rheumatic fever, even though symptoms typically resolve in 3-4 days 1, 2, 4. Therapy can be safely postponed up to 9 days after symptom onset and still prevent rheumatic fever 4.

Treatment for Penicillin-Allergic Patients

Non-Anaphylactic/Delayed Penicillin Allergy

First-generation cephalosporins are the preferred alternative with only 0.1% cross-reactivity risk in patients with non-severe, delayed reactions 2, 6:

• Cephalexin: 500 mg orally twice daily for 10 days 2, 6, 4
• Cefadroxil: 1 gram orally once daily for 10 days 2, 6

Immediate/Anaphylactic Penicillin Allergy

All beta-lactams must be avoided due to up to 10% cross-reactivity risk 1, 2, 6. Use non-beta-lactam alternatives:

• Clindamycin (preferred): 300 mg orally three times daily for 10 days 1, 2, 6

  • Only ~1% resistance rate in the United States 2, 6
  • Highly effective even in chronic carriers 2, 6, 7

• Azithromycin: 500 mg orally once daily for 5 days 1, 2, 6

  • Only antibiotic requiring just 5 days due to prolonged tissue half-life 1, 2, 4
  • However, 5-8% macrolide resistance in the United States (varies geographically) 2, 6

• Clarithromycin: 250 mg orally twice daily for 10 days 1, 2, 6

  • Similar resistance concerns as azithromycin 2, 6

Clindamycin is more reliable than macrolides when beta-lactams cannot be used, given the low resistance rate and high efficacy 2, 6.

Adjunctive Symptomatic Treatment

• Acetaminophen or NSAIDs (like ibuprofen) for moderate to severe symptoms or high fever 1, 2
• Avoid aspirin in children due to Reye syndrome risk 1, 2, 4
• Corticosteroids are not recommended as adjunctive therapy 1, 2

Critical Pitfalls to Avoid

• Never shorten the antibiotic course below 10 days (except azithromycin's 5-day regimen), as this dramatically increases treatment failure and rheumatic fever risk 1, 2, 4
• Do not use cephalosporins in patients with immediate/anaphylactic penicillin reactions due to 10% cross-reactivity 2, 6
• Avoid tetracyclines, sulfonamides, trimethoprim-sulfamethoxazole, and fluoroquinolones due to high resistance rates and ineffectiveness 2, 4
• Do not prescribe broad-spectrum cephalosporins (cefdinir, cefixime, cefpodoxime) when narrow-spectrum first-generation agents are appropriate 2, 6
• Do not routinely test or treat asymptomatic household contacts 1, 2
• Follow-up throat cultures are not routinely recommended for asymptomatic patients who completed therapy 1, 2

Special Considerations

For patients with recurrent streptococcal pharyngitis, consider that they may be chronic pharyngeal carriers experiencing repeated viral infections rather than true recurrent strep infections 1, 2. Chronic carriers generally do not require treatment as they are unlikely to spread infection and are at little risk for complications 2.

For chronic carriers who have failed penicillin treatment, clindamycin demonstrates particularly high efficacy in eradicating the organism 2, 6, 7.