Why is a strep (streptococcal) screen not routinely checked in children under 2 years old with pharyngitis?

Why Strep Screening is Not Routinely Recommended in Children Under 2 Years Old with Pharyngitis

Strep screening is not routinely recommended in children under 2 years old with pharyngitis because Group A Streptococcal (GAS) pharyngitis is uncommon in this age group, and the risk of developing acute rheumatic fever (ARF) - the most serious complication - is extremely rare in children under 3 years of age. 1

Epidemiological Rationale

• Low prevalence: GAS pharyngitis primarily occurs in children 5-15 years of age, making it uncommon in children under 2 years 1
• Extremely rare complications: Reports of acute rheumatic fever in children under 3 years are very rare 1
  • In a large study from Salt Lake City, only 5% of ARF cases involved children under 5 years, with a median age of 4 years 1
  • This is likely because multiple exposures to GAS or immune system priming is needed before developing the immune response that leads to rheumatic fever 1

Clinical Presentation Differences

• In children under 3 years, GAS infection typically presents differently than in older children:

  • Fever with mucopurulent rhinitis
  • Excoriated nares
  • Diffuse adenopathy
  • Exudative pharyngitis is rare in this age group 1

• These symptoms often overlap with viral infections, making clinical differentiation difficult 1

Evidence-Based Recommendations

The Infectious Diseases Society of America (IDSA) explicitly states:

• "Diagnostic studies for GAS pharyngitis are not indicated for children <3 years old because acute rheumatic fever is rare in children <3 years old and the incidence of streptococcal pharyngitis and the classic presentation of streptococcal pharyngitis are uncommon in this age group." 1

Exceptions to Consider

While routine testing is not recommended, there are specific situations where testing younger children may be appropriate:

• Children with risk factors such as an older sibling with GAS infection 1
• Children between 2-3 years may have higher rates of GAS than those under 2 years 2
  • One study found 29% of children 2-3 years with pharyngeal erythema were positive for GAS compared to only 7% of controls 2

Clinical Approach

For children under 2 years with pharyngitis:

1. Focus on symptomatic management appropriate for age 3
2. Consider testing only if specific risk factors exist (e.g., older sibling with GAS)
3. Be aware that clinical findings alone cannot reliably distinguish bacterial from viral pharyngitis 4

Potential Pitfalls

• Unnecessary antibiotic use: Testing and treating young children unnecessarily can lead to antibiotic resistance, side effects, and increased healthcare costs
• False reassurance: Even in older children, symptoms and signs (individually or combined) cannot definitively rule in or rule out streptococcal pharyngitis 4
• Missing true cases: If testing is indicated due to risk factors, physical examination alone is insufficient to identify GAS pharyngitis 2

By following these evidence-based guidelines, clinicians can avoid unnecessary testing and treatment while appropriately managing pharyngitis in children under 2 years of age.