When should nasal colonisation with Group A Streptococcus be treated in an otherwise healthy asymptomatic individual?

When to Treat Nasal Group A Streptococcus Colonization

Do not treat asymptomatic nasal colonization with Group A Streptococcus in otherwise healthy individuals—routine testing and treatment of asymptomatic carriers is not recommended. 1, 2

Rationale for Non-Treatment

Asymptomatic carriers of Group A Streptococcus (GAS) in the nasopharynx or throat do not require antimicrobial therapy for several evidence-based reasons:

• Carriers lack immunologic response to the organism and are at very low risk—if any—for developing suppurative complications (peritonsillar abscess, cervical lymphadenitis) or nonsuppurative sequelae such as acute rheumatic fever or post-streptococcal glomerulonephritis. 1

• Transmission risk is minimal: Streptococcus carriers are unlikely to spread the organism to their close contacts, making treatment for infection control purposes unnecessary. 1

• Eradication is difficult: It is much more challenging to eradicate GAS from the upper respiratory tract of carriers compared to patients with acute infections, even with optimal antibiotic therapy. 1

• Prevalence is high: Up to 20% of asymptomatic school-aged children may be GAS carriers during winter and spring in temperate climates, making routine treatment impractical and unnecessary. 1, 2

Specific Exceptions Requiring Treatment

Treatment of asymptomatic nasal or pharyngeal GAS colonization is indicated only in specific high-risk situations:

1. History of Rheumatic Fever

• Patients with a previous episode of acute rheumatic fever are at unusually high risk for recurrence and require treatment of colonization to prevent rheumatic fever recurrence. 1, 3
• These patients may also require continuous antimicrobial prophylaxis rather than episodic treatment. 1

2. Outbreak Settings

• During outbreaks of acute rheumatic fever or post-streptococcal glomerulonephritis in the community. 3
• During outbreaks in closed or semi-closed communities (military barracks, nursing homes, schools with multiple cases). 3

3. Multiple Recurrent Symptomatic Episodes

• When a patient experiences multiple, recurrent episodes of documented GAS pharyngitis within a short period, testing and treating household contacts may be warranted to interrupt "ping-pong" transmission. 1, 3
• This is distinct from treating isolated asymptomatic colonization and requires documentation of repeated symptomatic infections in the index patient. 3

4. Close Contact with Invasive GAS Disease

• Household or intimate contacts of patients with severe invasive GAS infections (necrotizing fasciitis, streptococcal toxic shock syndrome) should be monitored closely and may require throat swab surveys with targeted prophylaxis. 1, 4
• This represents a fundamentally different clinical scenario than routine pharyngeal colonization. 4

Common Clinical Pitfalls

Avoid treating asymptomatic household contacts of patients with routine GAS pharyngitis. 1, 2, 4

• Routine culture or testing of asymptomatic household contacts is not recommended except in the specific high-risk situations outlined above. 1
• Approximately one-third of households may develop secondary symptomatic cases, but these individuals should be tested and treated only when symptomatic. 4

Do not perform routine post-treatment cultures in asymptomatic patients. 2, 3

• Routine retesting after completing antibiotic therapy is unnecessary and may lead to inappropriate retreatment of carriers who have intercurrent viral infections. 1, 2
• Post-treatment testing should only be performed in patients who remain symptomatic or have special risk factors (history of rheumatic fever, outbreak situations). 3

Distinguish carriers with viral infections from treatment failures. 1, 3

• Carriers may develop intercurrent viral pharyngitis and test positive for GAS, appearing to have acute streptococcal pharyngitis when they actually have a viral illness. 1
• Symptoms such as cough, congestion, rhinorrhea, and ear pain suggest viral infection rather than isolated GAS pharyngitis. 3

Treatment Regimens When Indicated

If treatment is warranted in the specific high-risk situations above, use regimens proven effective for carrier eradication rather than standard acute pharyngitis treatment:

• Clindamycin: 20-30 mg/kg/day in 3 divided doses for children (adults: 600 mg/day in 2-4 divided doses) for 10 days. 1

• Amoxicillin-clavulanate: 40 mg/kg/day in 3 divided doses for children (adults: 500 mg twice daily) for 10 days. 1

• Benzathine penicillin G (single intramuscular dose) with or without rifampin (20 mg/kg/day in 2 divided doses for 4 days). 1

These regimens have superior carrier eradication rates compared to standard penicillin therapy. 1, 3