What is the recommended antibiotic treatment for strep throat?

Treatment of Strep Throat

Penicillin V or amoxicillin for 10 days is the first-line treatment for strep throat, with no documented penicillin resistance ever reported worldwide. 1, 2

First-Line Antibiotic Therapy

Oral penicillin or amoxicillin remains the gold standard due to proven efficacy, narrow spectrum, safety profile, and low cost. 1, 2

Dosing Recommendations:

Penicillin V:

• Children: 250 mg twice or three times daily for 10 days 1
• Adolescents and adults: 500 mg twice or three times daily for 10 days 1

Amoxicillin:

• 50 mg/kg once daily (maximum 1000 mg) for 10 days 1, 2
• Amoxicillin is often preferred in young children due to better palatability of the suspension 1
• Once-daily dosing improves adherence compared to multiple daily doses 1, 2

Intramuscular benzathine penicillin G:

• 600,000 units for patients <27 kg 1
• 1,200,000 units for patients ≥27 kg 1
• This option is particularly important for patients unlikely to complete oral therapy, those with history of rheumatic fever, or those in high-risk populations (crowded living conditions, low socioeconomic status) 1

Treatment for Penicillin-Allergic Patients

For non-anaphylactic penicillin allergy:

• First-generation cephalosporins (e.g., cephalexin) for 10 days 1, 2
• These should NOT be used in patients with immediate-type hypersensitivity to β-lactams 1

For immediate hypersensitivity to penicillin:

• Clindamycin: 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days 2, 3
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 2, 4
• Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg per dose) for 10 days 2
• Erythromycin: various formulations available for 10 days 1

Important caveat: Azithromycin is FDA-approved for strep throat only as an alternative to first-line therapy in individuals who cannot use first-line therapy, not as a primary option. 4 Approximately 1% of azithromycin-susceptible strains become resistant following therapy. 4

Critical Treatment Principles

The full 10-day course must be completed to ensure complete eradication of Group A Streptococcus and prevent rheumatic fever, even though symptoms typically resolve within 3-4 days. 1, 2

Therapy can be safely delayed up to 9 days after symptom onset and still prevent rheumatic fever, allowing time for throat culture confirmation before starting antibiotics. 1 However, early treatment reduces symptom duration by 1-2 days and decreases contagiousness after 24 hours of antibiotics. 1

Diagnosis should be confirmed by either throat culture or rapid antigen detection test before initiating antibiotics. 1, 2 If clinical suspicion is high, treatment can be started while awaiting culture results, but should be discontinued if the test is negative. 1

What NOT to Use as First-Line Therapy

Avoid broad-spectrum antibiotics like amoxicillin-clavulanate (Augmentin) as first-line therapy because they increase costs, promote antimicrobial resistance, and cause higher rates of gastrointestinal side effects without providing additional clinical benefit. 2

Augmentin is reserved for:

• Chronic GAS carriers: 40 mg amoxicillin/kg/day in three divided doses (maximum 2,000 mg/day) for 10 days 2, 5
• Recurrent pharyngitis with documented treatment failures 5

Never use these agents for strep throat:

• Tetracyclines (high resistance rates) 5
• Sulfonamides/trimethoprim-sulfamethoxazole (do not eradicate GAS) 5
• Older fluoroquinolones like ciprofloxacin (limited activity against GAS) 5

Management of Treatment Failure

True penicillin resistance has never been documented in Group A Streptococcus anywhere in the world. 2, 5 Apparent treatment failures are typically due to:

• Poor adherence to the 10-day regimen 6
• Reinfection from household contacts 5
• Chronic carrier state with intercurrent viral pharyngitis 1

For documented penicillin failure:

• Clindamycin 300 mg four times daily for 10 days in adults is the preferred agent 5
• First-generation cephalosporins are acceptable alternatives 5
• Do NOT switch to amoxicillin or ampicillin as they are penicillin congeners and will fail for the same reasons 5

Common Pitfalls to Avoid

Do not treat chronic carriers routinely. They are at low risk of transmitting disease or developing complications and generally do not require treatment. 1, 3

Do not perform post-treatment testing in asymptomatic patients, as this may detect chronic carriers rather than treatment failure. 3

Screen and treat household contacts if recurrent infections occur frequently, as reexposure can cause apparent treatment failure. 5

Tonsillectomy is not recommended solely to reduce the frequency of strep throat episodes. 3