Is a strep (streptococcal) culture indicated for a 20-month-old baby with symptoms of pharyngitis?

Strep Testing in a 20-Month-Old Child

No, you should not routinely perform strep culture or rapid antigen detection testing on a 20-month-old baby with pharyngitis. 1

Primary Recommendation

Diagnostic studies for group A streptococcal (GAS) pharyngitis are not indicated for children under 3 years of age because:

• Acute rheumatic fever is rare in this age group 1
• The incidence of streptococcal pharyngitis is uncommon in children under 3 years 1
• The classic presentation of streptococcal pharyngitis is atypical in this age group 1
• GAS pharyngitis is most commonly observed in children 5-15 years of age 1

Exception: When Testing May Be Considered

Testing may be considered in selected circumstances if the child has specific risk factors, such as:

• An older sibling with documented GAS infection 1
• Close household contact with confirmed streptococcal pharyngitis 1

This recommendation carries a strong strength with moderate quality evidence from the Infectious Diseases Society of America guidelines. 1

Clinical Reasoning

The rationale for avoiding routine testing in this age group is multifactorial:

• Low disease prevalence: Only 20-30% of acute pharyngitis in the typical pediatric population (ages 5-15) is due to GAS, and this percentage is even lower in children under 3 years 1
• Minimal risk of complications: The primary rationale for treating GAS pharyngitis is preventing acute rheumatic fever, which is exceptionally rare in children under 3 years 1
• Avoiding unnecessary antibiotics: Testing young children without risk factors leads to identification of asymptomatic carriers rather than true infections, resulting in unnecessary antibiotic prescriptions and contributing to antimicrobial resistance 1

When to Suspect Viral Etiology

Do not test if clinical features strongly suggest viral pharyngitis, including:

• Cough 1
• Rhinorrhea (runny nose) 1
• Hoarseness 1
• Conjunctivitis 1
• Diarrhea 1

These features make viral pharyngitis far more likely and testing unnecessary regardless of age. 1

Common Pitfall to Avoid

The most common error is overtesting young children with pharyngitis, leading to:

• Identification of asymptomatic GAS carriers (approximately 25% of the population) rather than acute infection 1
• Unnecessary antibiotic prescriptions 1
• Increased healthcare costs 2
• Contribution to antimicrobial resistance 1