What is the difference in management between upper respiratory tract infection (URTI) and lower respiratory tract infection (LRTI)?

Management Differences Between Upper and Lower Respiratory Tract Infections

The key management difference is that lower respiratory tract infections (LRTIs) require antibiotics when pneumonia is suspected or confirmed, while upper respiratory tract infections (URTIs) rarely require antibiotics and are typically self-limiting viral illnesses. 1

Anatomical and Clinical Differentiation

URTIs affect structures above the larynx (nose, sinuses, pharynx, larynx), while LRTIs affect structures below the larynx (trachea, bronchi, bronchioles, lung parenchyma). 1

LRTI Clinical Presentation

• Cough as the main symptom plus at least one of: sputum production, dyspnea, wheeze, or chest discomfort/pain 2
• Illness duration ≤21 days 2
• No alternative explanation such as sinusitis or asthma 2

When to Suspect Pneumonia (Critical Decision Point)

Suspect pneumonia when acute cough is present PLUS any one of the following:

• New focal chest signs on examination 2, 1
• Dyspnea or tachypnea 2, 1
• Pulse rate >100 bpm 2
• Fever lasting >4 days 2, 1

If pneumonia is suspected, obtain a chest radiograph to confirm diagnosis before initiating antibiotics. 2, 1

Diagnostic Workup Differences

For Suspected LRTI/Pneumonia

• C-reactive protein (CRP) testing can guide diagnosis: 2
  • CRP <20 mg/L with symptoms >24 hours makes pneumonia highly unlikely 2
  • CRP >100 mg/L makes pneumonia likely 2
• Chest X-ray is mandatory when pneumonia is suspected 2, 1

Critical Alternative Diagnoses to Consider in LRTI Presentations

• Left ventricular failure: Consider in patients >65 years with orthopnea, displaced apex beat, or history of myocardial infarction, hypertension, or atrial fibrillation 2
  • BNP <40 pg/mL or NT-proBNP <150 pg/mL makes heart failure unlikely 2
• Pulmonary embolism: Consider with history of DVT, immobilization in past 4 weeks, or malignancy 2
• Aspiration pneumonia: Consider in patients with swallowing difficulties 2
• Chronic airway disease: Consider in patients with wheezing, prolonged expiration, smoking history, and allergy symptoms 2

Antibiotic Treatment Decisions

When Antibiotics ARE Indicated for LRTI

Antibiotics should be prescribed in the following situations: 2, 1

• Suspected or confirmed pneumonia 2, 1
• COPD exacerbations with all three cardinal symptoms: increased dyspnea, increased sputum volume, AND increased sputum purulence 2, 3
• Severe COPD exacerbations (even with fewer symptoms) 3
• Age >75 years with fever 2
• Cardiac failure present 2
• Insulin-dependent diabetes mellitus 2
• Serious neurological disorder 2

When Antibiotics Are NOT Indicated

• Simple URI symptoms without meeting LRTI criteria 3
• Acute bronchitis in patients without chronic lung disease (typically viral and self-limiting) 2
• COPD patients with URI symptoms not meeting exacerbation criteria 3

First-Line Antibiotic Selection for LRTI

First-choice antibiotics: 2, 1, 3

• Amoxicillin 500-1000 mg three times daily 3
• Tetracycline/Doxycycline 100 mg twice daily 3

For penicillin allergy: 2, 1, 3

• Newer macrolides (azithromycin, roxithromycin, clarithromycin) in areas with low pneumococcal macrolide resistance 2, 1, 3

Treatment duration: 5 days when clinical signs of bacterial infection are present 3

Symptomatic Treatment for LRTI

• Dextromethorphan or codeine can be prescribed for dry, bothersome cough 2
• Do NOT prescribe: Expectorants, mucolytics, antihistamines, or bronchodilators for acute LRTI in primary care 2

Monitoring and Follow-Up

LRTI Patients Should Return If:

• Symptoms persist >3 weeks 2, 1, 3
• No improvement within 3 days of antibiotic initiation 1, 3
• Fever exceeds 4 days 3
• Dyspnea worsens 3
• Patient stops drinking or has decreased consciousness 3

Seriously Ill Patients Require Reassessment

Reassess within 2 days if patient has: 3

• High fever
• Tachypnea
• Dyspnea
• Relevant comorbidity
• Age >65 years

Common Pitfalls to Avoid

• Failing to obtain chest X-ray when pneumonia is suspected leads to missed diagnoses and inappropriate antibiotic withholding 2, 1
• Prescribing antibiotics for simple URI symptoms or viral acute bronchitis contributes to antibiotic resistance without patient benefit 3
• Missing cardiac failure or pulmonary embolism in patients presenting with respiratory symptoms, particularly in elderly patients 2, 1
• Treating COPD exacerbations with antibiotics when cardinal symptoms are absent is inappropriate and promotes resistance 3
• Ignoring local antibiotic resistance patterns when selecting empiric therapy can lead to treatment failure 2, 3