Treatment of Upper Respiratory Tract Infections Based on Lab Results
Most URTIs are viral and require only symptomatic treatment; antibiotics should be prescribed only when lab testing confirms bacterial infection, specifically a positive rapid antigen test (RAT) for Group A Streptococcus in pharyngitis or clinical/radiographic confirmation of bacterial sinusitis. 1, 2
Diagnostic Testing Strategy
For Pharyngitis
- Rapid Antigen Testing (RAT) is the cornerstone for treatment decisions - clinical signs alone cannot reliably distinguish streptococcal from viral pharyngitis 1
- RAT has approximately 90% sensitivity and specificity similar to throat culture 1
- Positive RAT = prescribe antibiotics immediately (Grade A evidence) 1
- Negative RAT with low acute rheumatic fever (ARF) risk = no antibiotics needed 1
- RAT is not routinely performed in children under 3 years as Group A Streptococcus is rarely involved 1
High-Risk Situations Requiring Culture After Negative RAT
Consider throat culture if negative RAT occurs with: 1
- Personal history of acute rheumatic fever
- Age 5-25 years with poor social/hygienic conditions or institutional living
- History of recurrent GAS pharyngitis
- Recent stay in streptococcal-endemic regions (Africa, West Indies)
- If culture is positive, initiate antibiotics 1
For Sinusitis
- Clinical diagnosis of acute purulent maxillary sinusitis warrants antibiotics (Grade B) - look for unilateral purulent rhinorrhea and tenderness over the sinus 1
- Lab testing is not routinely required for uncomplicated sinusitis 1
- Obtain sputum culture before antibiotics if hospitalization is required 1
Treatment Algorithm
When Lab Results Confirm Bacterial Infection
For GAS-Positive Pharyngitis:
- Amoxicillin is first-line treatment 2, 3
- Treatment duration: 10 days 2, 4
- For beta-lactam allergies: pristinamycin or macrolides 2, 4
For Bacterial Sinusitis:
- First-line: amoxicillin-clavulanate, second-generation oral cephalosporins, or third-generation oral cephalosporins 2, 4
- For beta-lactam allergies: pristinamycin or macrolides 2, 4
- Treatment duration: 7-10 days 2, 4
- For suspected resistant organisms: amoxicillin-clavulanate, cefuroxime-axetil, or cefpodoxime-proxetil 2, 4
When Lab Results Are Negative or Not Indicated
Symptomatic Treatment Only: 2
- Analgesics/antipyretics: acetaminophen or ibuprofen for pain, fever, and inflammation 2
- Adequate hydration and rest 2
- Nasal saline irrigation for persistent nasal congestion 2
- Dextromethorphan or codeine for bothersome dry cough 2
Critical Pitfalls to Avoid
- Never prescribe antibiotics empirically for viral URTIs - this contributes to antibiotic resistance without clinical benefit and does not prevent progression to lower respiratory tract infections 1, 2
- Do not use clinical scoring systems alone to diagnose streptococcal pharyngitis - only microbiological testing is reliable 1
- Avoid mucolytics, expectorants, or bronchodilators for uncomplicated viral URTIs as they provide no benefit 2
- NSAIDs at anti-inflammatory doses and systemic corticosteroids have no proven benefit in acute pharyngitis 1
When to Reassess or Escalate
Return for evaluation if: 2
- Symptoms persist beyond 3 weeks
- Fever exceeds 4 days
- Dyspnea worsens
- Patient's condition deteriorates
Red flags requiring immediate hospitalization and parenteral antibiotics: 1
- Meningeal syndrome
- Exophthalmos
- Palpebral edema
- Ocular mobility disorders
- Severe pain preventing sleep
Special Populations Requiring Closer Monitoring
High-risk patients include: 2
- Age ≥65 years
- Chronic cardiac or pulmonary diseases
- Diabetes mellitus
- Chronic renal diseases
The key principle: lab confirmation of bacterial infection drives antibiotic decisions, while viral URTIs receive symptomatic treatment only, regardless of symptom severity. 1, 2