Can a streptococcal test be performed in a 23‑month‑old patient?

Strep Testing in a 23-Month-Old: Generally Not Recommended

Streptococcal testing is generally NOT indicated in a 23-month-old child with pharyngitis, as this patient is under 3 years of age 1.

The Age-Based Guideline

The IDSA guidelines explicitly state that diagnostic studies for GAS pharyngitis are not indicated for children <3 years old (strong recommendation, moderate evidence) 1. This recommendation is based on three key factors:

• Acute rheumatic fever is rare in children under 3 years
• The incidence of streptococcal pharyngitis is uncommon in this age group
• The classic presentation of streptococcal pharyngitis is uncommon in toddlers

The Important Exception

However, testing MAY be considered in selected children <3 years old who have specific risk factors, particularly:

• An older sibling with documented GAS infection
• Other household contacts with confirmed GAS pharyngitis
• Attendance at daycare with a known GAS outbreak

This exception carries a strong recommendation with moderate evidence 1.

Supporting Evidence from Clinical Practice

Recent research confirms the guideline's validity. A 2021 study found that only 1.8% of children <3 years tested positive for GAS, compared to 19.4% in older children 2. Despite this low yield, testing in this age group remains overused—one quality improvement study showed that 48% of inappropriate GAS testing occurred in children under 3 years 3.

Interestingly, one older emergency department study (1999) found that 29% of children aged 2-3 years with pharyngeal erythema tested positive for GAS 4, but this conflicts with more recent data and the established guidelines, which remain the authoritative source.

Clinical Pitfalls to Avoid

• Don't test based on pharyngeal erythema alone in this age group—physical examination findings don't reliably distinguish GAS from viral causes in toddlers 4
• Don't test if viral features are present (cough, rhinorrhea, hoarseness, oral ulcers) regardless of age 1
• Avoid unnecessary antibiotic exposure—51% of inappropriately tested children receive antibiotics, leading to potential adverse effects and resistance 3

The Bottom Line Algorithm

For a 23-month-old with pharyngitis:

1. First, assess for viral features (cough, rhinorrhea, hoarseness, oral ulcers)

   • If present → Do NOT test 1

2. If no clear viral features, check for high-risk exposures:

   • Older sibling or household contact with confirmed GAS? → Consider testing 1
   • No high-risk exposure? → Do NOT test 1

3. If testing is performed and positive:

   • Treat with penicillin or amoxicillin for 10 days 5
   • Back up positive RADT with culture is not necessary (RADTs are highly specific) 1

The risk of acute rheumatic fever—the primary reason for treating GAS pharyngitis—is exceptionally rare in this age group, making routine testing more likely to cause harm through unnecessary antibiotic use than to provide benefit 1.