Testing Asymptomatic Contacts of Strep Throat
An asymptomatic patient with a relative positive for strep throat should NOT be tested or treated, as testing and treatment are only indicated for patients with signs and symptoms of acute pharyngitis. 1
Clinical Rationale
The Infectious Diseases Society of America guidelines are explicit that testing should be reserved for patients presenting with clinical features of pharyngitis 1. Here's the algorithmic approach:
When Testing Is NOT Indicated
- Asymptomatic contacts should not be tested, even with known exposure to a documented case of strep throat 1
- Testing in the absence of symptoms leads to identification of asymptomatic carriers rather than true infections 1
- The guidelines emphasize that "testing usually need not be performed for patients with acute pharyngitis whose clinical and epidemiological features do not suggest a group A streptococcal etiology" - and this applies even more strongly to those without any pharyngitis symptoms 1
When Testing SHOULD Be Considered
Testing is only appropriate when the patient develops clinical symptoms suggesting pharyngitis 1:
- Sore throat (generally of sudden onset) with pain on swallowing 1
- Fever (documented or by history) 1, 2
- Physical examination findings: tonsillopharyngeal erythema with or without exudates, tender enlarged anterior cervical lymph nodes, palatal petechiae, or beefy red swollen uvula 1, 2
Important Clinical Pitfalls
- Carrier state confusion: A positive test in an asymptomatic person likely represents colonization (carrier state) rather than active infection requiring treatment 1
- No benefit to prophylactic treatment: There is no evidence supporting treatment of asymptomatic household contacts, even during outbreaks 1
- Selective testing improves accuracy: Testing only symptomatic patients increases the proportion of positive tests that represent true infections rather than carrier states 1
What to Tell the Patient
- Monitor for symptoms: Watch for development of sore throat, fever, or difficulty swallowing over the next several days 1
- Seek care if symptomatic: If symptoms develop, return for evaluation and testing at that time 1
- No testing needed now: Being asymptomatic means testing would not change management and could lead to unnecessary antibiotic exposure 1
The Evidence Behind This Recommendation
The IDSA guidelines from 2002 (the most recent comprehensive guideline on this topic) explicitly state that bacteriologic studies should only be performed when the diagnosis of strep pharyngitis cannot be confidently excluded on clinical and epidemiologic grounds 1. In an asymptomatic patient, the diagnosis IS confidently excluded regardless of exposure history 1.
Close contact with a documented case is noted as "helpful" epidemiologic information, but only in the context of a patient already presenting with pharyngitis symptoms - it does not justify testing asymptomatic individuals 1.