Management of Asymptomatic Infant Exposed to Household Group A Streptococcus
Do not test or treat this asymptomatic infant, even with household exposure to Group A streptococcus. 1
Rationale for No Testing or Treatment
The Infectious Diseases Society of America provides a strong recommendation (with moderate-quality evidence) against routine diagnostic testing or empiric treatment of asymptomatic household contacts of patients with GAS pharyngitis. 1 This recommendation applies regardless of the number of infected household members.
Key Supporting Evidence
Asymptomatic carriage is common and benign: Up to 25-33% of household contacts may harbor GAS in their upper respiratory tracts without active infection. 1 These carriers have no immunologic reaction to the organism and are at low risk for developing complications such as acute rheumatic fever or post-streptococcal glomerulonephritis. 1, 2
Antibiotic prophylaxis is ineffective: Studies examining penicillin prophylaxis for household contacts have not shown reduction in the incidence of subsequent GAS pharyngitis. 1 While cephalosporin prophylaxis showed a small statistically significant effect, the clinical benefit does not outweigh the risks. 1
Risks outweigh benefits: Antibiotic use carries risks of adverse effects including rash, diarrhea, and rarely anaphylaxis, plus contributes to antibiotic resistance in the population. 1 Given the self-limited nature of GAS pharyngitis and high frequency of asymptomatic carriage, routine treatment is not warranted. 1
Special Considerations for Infants Under 3 Years
This recommendation is particularly appropriate for an infant because:
GAS pharyngitis is rare in children <3 years old: The prevalence of true GAS infection is very low in this age group. 1 When GAS infection does occur in children under 3, it typically presents with fever, mucopurulent rhinitis, excoriated nares, and diffuse adenopathy—not classic exudative pharyngitis. 1
Acute rheumatic fever is extremely rare in infants: Reports of ARF in children <3 years are very rare. 1 In a series of 541 new ARF cases, only 5% involved children <5 years of age, with a median age of 4 years. 1 This is thought to occur because repeated exposures to GAS are needed to prime the immune system before an immune response can lead to rheumatic fever. 1
Limited utility of testing in this age group: The low prevalence of GAS pharyngitis combined with the low risk of developing ARF in children <3 years limits the usefulness of diagnostic testing. 1
When to Reconsider: Monitor for Symptoms
Only test and treat if the infant develops symptoms suggestive of GAS infection, which in this age group would include: 1, 3
- Fever
- Mucopurulent rhinitis
- Excoriated nares
- Diffuse adenopathy
- Irritability
- Reddened throat or palate
If symptoms develop, obtain throat culture (and consider anterior nares culture in children 18-36 months) before initiating antibiotics. 3
Common Pitfalls to Avoid
Do not perform "screening" cultures on asymptomatic household members: This leads to unnecessary antibiotic use and does not prevent secondary illness. 1
Do not confuse asymptomatic carriage with active infection: A positive culture in an asymptomatic child represents colonization, not disease requiring treatment. 1, 2
Do not assume the negative throat culture in the infant means future protection: The infant could still develop symptomatic GAS infection later, but prophylactic treatment now is not indicated. 1
Exception: Ping-Pong Transmission
The only scenario where testing household contacts might be considered is when there are multiple repeated episodes of symptomatic GAS pharyngitis occurring in family members over months, suggesting "ping-pong" transmission. 1 In that specific circumstance, simultaneous cultures of all family members with treatment of those who are positive may be helpful. 1 However, this does not apply to a single outbreak or initial exposure as described in this case. 1