In a 70‑year‑old woman with an 8‑hour history of sore throat, mild fatigue, and low‑grade fever (99.3 °F) and a negative rapid influenza A/B antigen test, is it too early for the influenza test to be reliable, and should a rapid group A streptococcal antigen test be performed now with appropriate symptomatic treatment?

Management of Acute Pharyngitis in a 70-Year-Old with Negative Influenza Testing

Influenza Testing Timing

The negative rapid influenza test performed at 8 hours after symptom onset is too early to be reliable, as viral shedding may not yet be sufficient for detection; however, given the clinical presentation with isolated sore throat, low-grade fever, and absence of respiratory symptoms, influenza is unlikely and retesting is not indicated. 1

• Rapid influenza tests have optimal sensitivity when performed 24–72 hours after symptom onset, when viral shedding peaks 1
• The clinical picture—isolated sore throat without cough, rhinorrhea, or other respiratory features—strongly suggests a non-influenza etiology 1
• Influenza typically presents with prominent systemic symptoms (myalgias, severe fatigue, high fever) and respiratory features (cough, rhinorrhea), which are absent here 1

Streptococcal Testing Decision

A rapid streptococcal antigen test should be performed now, because the patient presents with fever and sore throat without viral features, and a negative RADT alone is sufficient to rule out Group A Streptococcus in adults without requiring a backup throat culture. 1, 2

• Testing is indicated when patients present with sore throat and fever in the absence of viral features such as cough, rhinorrhea, hoarseness, or conjunctivitis 1
• In adults, a negative RADT has ≥95% specificity and is sufficient to exclude streptococcal pharyngitis without confirmatory throat culture, because the prevalence of Group A Streptococcus is only 5–10% in adults and the risk of acute rheumatic fever is virtually zero 1, 2, 3
• The 70-year-old age group has an extremely low incidence of streptococcal pharyngitis, further supporting the reliability of RADT alone 1

Management Algorithm

If RADT is Positive

• Prescribe penicillin V 500 mg twice or three times daily for 10 days as first-line therapy 1
• Alternative: amoxicillin 50 mg/kg once daily (maximum 1 g) for 10 days 1
• For penicillin allergy (non-anaphylactic): first-generation cephalosporin for 10 days 1
• For anaphylactic penicillin allergy: clindamycin 300 mg three times daily for 10 days or azithromycin 500 mg once daily for 5 days 1, 4

If RADT is Negative

Withhold all antibiotics and provide symptomatic treatment only, as the infection is overwhelmingly viral and self-limited. 1, 2

• Offer ibuprofen or acetaminophen for pain and fever relief 1, 2
• Recommend saltwater gargles, throat lozenges, and warm liquids with honey for comfort 2
• Reassure that symptoms typically resolve within 3–4 days even without antibiotics 1
• No backup throat culture is needed in adults with negative RADT 1, 2, 3

Critical Pitfalls to Avoid

• Do not prescribe antibiotics based on clinical appearance alone (e.g., pharyngeal erythema or exudates), as these findings occur in both viral and bacterial infections 1, 2
• Do not order a backup throat culture after a negative RADT in adults, as this wastes resources and offers no clinical benefit 1, 2, 3
• Do not retest for influenza unless respiratory symptoms develop or the clinical picture changes significantly 1
• Avoid aspirin in the setting of possible viral illness due to Reye syndrome risk, though this is primarily a pediatric concern 1

When to Reconsider the Diagnosis

• If symptoms persist beyond 3–4 days or worsen significantly, consider suppurative complications (peritonsillar abscess, retropharyngeal abscess) or alternative diagnoses such as infectious mononucleosis 2, 5
• The presence of severe dysphagia, drooling, trismus, or respiratory distress warrants immediate evaluation for deep space infections or epiglottitis 5