In an 83‑year‑old man with sore throat, should I perform a rapid antigen detection test for group A Streptococcus before starting antibiotics?

Strep Testing in an 83-Year-Old Male with Sore Throat

Direct Recommendation

In an 83-year-old man with sore throat, you should perform a rapid antigen detection test (RADT) only if clinical features suggest bacterial rather than viral pharyngitis, but a negative RADT alone is sufficient to rule out group A streptococcal infection without requiring backup throat culture. 1, 2

Clinical Assessment Before Testing

Before ordering any test, evaluate for features that suggest viral etiology, which would make testing unnecessary:

• Do not test if the patient has cough, rhinorrhea, hoarseness, conjunctivitis, or oral ulcers—these strongly indicate viral infection 1
• Consider testing if the patient presents with sudden onset sore throat, fever, tonsillopharyngeal erythema with exudate, tender anterior cervical lymphadenopathy, or absence of viral features 1, 3

The key distinction here is that adults, particularly elderly patients, have only a 5-10% prevalence of group A streptococcal pharyngitis compared to 20-30% in children aged 5-15 years 2. This low pretest probability in an 83-year-old makes clinical judgment about viral features especially important.

Testing Algorithm for This Patient

If you decide to test based on clinical features:

• Perform a rapid antigen detection test (RADT) 1
• A negative RADT is sufficient—do not order a backup throat culture in adults 1, 2
• The specificity of RADT is ≥95%, making false positives rare, while sensitivity is 80-90% 2
• Adults have extremely low risk of acute rheumatic fever, making the risk-benefit ratio favor accepting the 10-20% false-negative rate rather than pursuing backup culture 1, 2

This differs significantly from pediatric management, where backup throat culture is required after negative RADT due to higher disease prevalence and rheumatic fever risk 1, 2.

Management Based on Test Results

If RADT is positive:

• Prescribe penicillin or amoxicillin for 10 days 1
• For penicillin allergy (non-anaphylactic), use first-generation cephalosporin 1
• For immediate hypersensitivity, use clindamycin or clarithromycin 1

If RADT is negative:

• Withhold antibiotics entirely 2
• Provide symptomatic treatment only: acetaminophen or ibuprofen for pain and fever 2
• Reassure the patient that symptoms typically resolve in less than 1 week 2
• Antibiotics shorten sore throat duration by only 1-2 days, with number needed to treat of 6 at 3 days 2

Critical Pitfalls to Avoid

• Do not prescribe antibiotics based on clinical appearance alone without laboratory confirmation—white patches and exudate occur with viral infections and do not reliably distinguish bacterial from viral causes 2
• Do not order backup throat culture after negative RADT in adults—this is a pediatric-specific recommendation that does not apply to your 83-year-old patient 1, 2
• Do not test or treat asymptomatic household contacts—this is not recommended even with confirmed cases 2
• Up to 70% of patients with sore throats receive unnecessary antibiotic prescriptions, while only 20-30% actually have group A streptococcal pharyngitis 2

Special Considerations for Elderly Patients

While the guidelines do not specifically address age >65 years, the rationale for not requiring backup culture in adults applies even more strongly to an 83-year-old:

• Extremely low incidence of group A streptococcal pharyngitis in this age group 2
• Virtually zero risk of acute rheumatic fever 1, 2
• Higher risk of antibiotic-related adverse effects in elderly patients
• Most sore throats in this population are viral and self-limited 1, 2

The primary justification for treating confirmed streptococcal pharyngitis is prevention of acute rheumatic fever and suppurative complications—both exceedingly rare in elderly adults. 2