What is the recommended treatment for Streptococcus pyogenes (Group A) oral infections, such as pharyngitis?

Treatment for Streptococcus pyogenes (Group A) Oral Infections

Penicillin or amoxicillin for 10 days is the first-line treatment for Group A Streptococcal (GAS) pharyngitis, with alternative regimens available for penicillin-allergic patients. 1

Diagnosis

Before initiating treatment, proper diagnosis is essential:

• Clinical features alone are insufficient for diagnosis of GAS pharyngitis
• Use Centor Criteria to assess likelihood of GAS pharyngitis:
  • Tonsillar exudates
  • Tender anterior cervical lymph nodes
  • Lack of cough
  • Fever
• Patients with 3-4 Centor criteria should be tested using:
  • Rapid antigen detection tests (RADT)
  • Throat culture (90-95% sensitivity on sheep blood agar)
• Positive RADT is diagnostic
• Negative RADT in children and adolescents should be backed up with culture 1

First-Line Treatment

For confirmed GAS pharyngitis:

• Penicillin V: 250 mg orally three times daily for 10 days 1
• Amoxicillin: 50 mg/kg once daily (maximum 1000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1

Alternative Regimens for Penicillin-Allergic Patients

• First-generation cephalosporins (if not anaphylactically sensitive) for 10 days 1
• Clindamycin: 300-450 mg orally three times daily for 10 days 1
• Azithromycin: 12 mg/kg once daily (max 500 mg) for 5 days 1, 2

Efficacy Considerations

• Azithromycin (500 mg once daily for 5 days) has shown clinical success rates comparable to penicillin in treating GAS pharyngitis, with clinical cure rates of 94-95% 2
• However, bacteriological eradication rates are significantly lower with azithromycin (31-38%) compared to penicillin (68-81%) 2
• Early initiation of therapy results in faster symptom resolution 1
• Therapy can be safely postponed up to 9 days after symptom onset and still prevent acute rheumatic fever 1

Treatment Duration

The full 10-day course of penicillin or amoxicillin is strongly recommended:

• Studies comparing 5-day vs. 10-day penicillin regimens show higher bacteriologic failure rates with shorter courses (18% vs. 6%) 1
• Twice-daily dosing of penicillin V (500 mg twice daily) is as effective as three or four times daily dosing 1

Symptomatic Relief

• Analgesics/antipyretics such as acetaminophen or NSAIDs for moderate to severe symptoms
• Avoid aspirin in children due to risk of Reye syndrome
• Topical remedies: warm salt water gargles, cold liquids, ice chips
• Maintain adequate hydration 1

Return to School/Work

• Patients are considered non-contagious after 24 hours of effective antibiotic therapy
• May return to school/work after 24 hours of appropriate antibiotics if feeling well and fever has resolved 1

Special Considerations

• For recurrent episodes, evaluate whether the patient has multiple true GAS infections or is a chronic carrier with viral infections
• Testing for GAS pharyngitis is usually not indicated in children under 3 years
• Follow-up throat cultures are not routinely indicated for asymptomatic patients who have completed appropriate therapy 1

Prevention

• Practice good hand hygiene
• Avoid sharing utensils, drinks, or food
• Cover mouth when coughing or sneezing 1