What antibiotic is recommended for atp (acute tonsillitis/pharyngitis)?

Antibiotic Treatment for Acute Tonsillitis/Pharyngitis

Penicillin V (250 mg twice daily or 500 mg twice daily for 10 days) or amoxicillin (50 mg/kg once daily, max 1000 mg, for 10 days) are the first-line antibiotics for confirmed Group A Streptococcal pharyngitis/tonsillitis. 1

When to Test and Treat

• Testing for Group A Streptococcus (GAS) is only indicated when clinical features suggest bacterial rather than viral etiology 1
• Do not test or treat patients with clear viral symptoms including cough, rhinorrhea, hoarseness, or oral ulcers 1
• Use rapid antigen detection test (RADT) or throat culture to confirm GAS before prescribing antibiotics 1, 2
• If RADT is negative in children, follow up with throat culture; in adults, culture backup is generally not necessary 3

First-Line Antibiotic Regimens for Confirmed GAS

For patients without penicillin allergy:

• Penicillin V: Children 250 mg twice or three times daily; adolescents/adults 250 mg four times daily or 500 mg twice daily for 10 days 1
• Amoxicillin: 50 mg/kg once daily (max 1000 mg) or 25 mg/kg twice daily (max 500 mg per dose) for 10 days 1
• Benzathine penicillin G (intramuscular): <27 kg: 600,000 units; ≥27 kg: 1,200,000 units as single dose 1

For penicillin-allergic patients (non-type I hypersensitivity):

• Cephalexin: 20 mg/kg/dose twice daily (max 500 mg/dose) for 10 days 1
• Cefadroxil: 30 mg/kg once daily (max 1 g) for 10 days 1

For type I penicillin allergy:

• Clindamycin: 7 mg/kg/dose three times daily (max 300 mg/dose) for 10 days 1
• Azithromycin: 12 mg/kg once daily (max 500 mg) for 5 days 1, 4
• Clarithromycin: 7.5 mg/kg/dose twice daily (max 250 mg/dose) for 10 days 1

Critical Considerations

• Penicillin and amoxicillin are preferred due to narrow spectrum, safety, low cost, and effectiveness against susceptible and intermediate-resistant pneumococci 1
• Macrolides (azithromycin, clarithromycin) have known resistance that varies geographically and temporally; they should not be first-line unless penicillin allergy exists 1, 4
• The 10-day duration for penicillins is essential to reduce risk of recurrent episodes and ensure adequate eradication 1
• Shorter courses with newer agents lack sufficient evidence for strong recommendations 1

When NOT to Prescribe Antibiotics

• Do not prescribe antibiotics for viral pharyngitis (most common cause of acute pharyngitis) 1, 5
• Do not treat asymptomatic household contacts 1
• Do not perform routine post-treatment cultures in asymptomatic patients 1
• Children under 3 years rarely need testing unless high-risk factors present (e.g., older sibling with GAS) 1

Common Pitfalls to Avoid

• Do not prescribe antibiotics empirically without confirming GAS infection - most acute pharyngitis is viral 1, 2, 5
• Do not use clinical features alone to diagnose streptococcal pharyngitis; laboratory confirmation is essential 1, 2, 6
• Do not assume exudative tonsillitis in children indicates streptococcal etiology - this is not a reliable indicator 7
• Do not prescribe antibiotics to prevent purulent complications in low-risk patients - this is not an indication for routine treatment 7
• Avoid aminoglycoside-containing preparations if topical therapy is considered, due to ototoxicity risk 1

Special Circumstances

For recurrent culture-positive episodes:

• Consider clindamycin 20-30 mg/kg/day in 3 doses for 10 days 1
• Alternative: amoxicillin-clavulanate 40 mg/kg/day in 3 doses for 10 days 1
• Benzathine penicillin G plus rifampin (20 mg/kg/day for last 4 days) may be beneficial 1

Chronic carriers (asymptomatic GAS colonization):

• Do not routinely treat carriers 1
• Treatment only indicated in outbreak settings, family history of rheumatic fever, or excessive family anxiety 1