What is the recommended treatment for bacterial versus viral pneumonia?

Treatment of Bacterial versus Viral Pneumonia

For bacterial pneumonia, use antibiotics targeted to the likely pathogen, while viral pneumonia generally does not require antibiotics but may benefit from supportive care and antiviral therapy for specific viral infections. 1

Bacterial Pneumonia Treatment

Community-Acquired Bacterial Pneumonia (Outpatient)

• For healthy adults without risk factors for drug-resistant pathogens:

  • First choice: Advanced generation macrolide (azithromycin 500mg on day 1, then 250mg daily for 4 days) 1
  • Alternative: Doxycycline for patients with macrolide allergies or intolerance 1

• For adults with comorbidities or risk factors for drug-resistant pathogens:

  • Either a β-lactam (amoxicillin, amoxicillin-clavulanate) plus a macrolide 1
  • OR a respiratory fluoroquinolone (levofloxacin or moxifloxacin) as monotherapy 1

Community-Acquired Bacterial Pneumonia (Inpatient)

• For non-ICU hospitalized patients:

  • β-lactam (ampicillin-sulbactam, cefotaxime, ceftriaxone, or ceftaroline) PLUS azithromycin or clarithromycin 1
  • OR respiratory fluoroquinolone monotherapy 1

• For ICU patients:

  • β-lactam plus either a macrolide or a respiratory fluoroquinolone 1
  • Add coverage for MRSA if risk factors present 1
  • Add coverage for Pseudomonas if risk factors present 1

Common Bacterial Pathogens and Specific Treatments

• Streptococcus pneumoniae: Penicillin G remains first choice for susceptible strains (7-10 days) 1
• Haemophilus influenzae: Ampicillin for non-β-lactamase-producing strains; amoxicillin-clavulanate for β-lactamase producers 1, 2
• Mycoplasma pneumoniae: Macrolide (e.g., azithromycin) or tetracycline 1
• Chlamydia pneumoniae: Macrolide or tetracycline 1
• Legionella: Erythromycin is the drug of choice 1
• Staphylococcus aureus: Penicillinase-resistant penicillin for methicillin-sensitive strains 1

Viral Pneumonia Treatment

• Generally, antibiotics are not indicated for confirmed viral pneumonia without bacterial co-infection 1
• Procalcitonin testing may help guide antibiotic decisions, with levels <0.1 mg/L suggesting viral infection, though this is not definitive 1
• A low procalcitonin value early in confirmed COVID-19 illness may support withholding or early discontinuation of antibiotics 1

Specific Viral Pneumonia Management

• Influenza: Consider neuraminidase inhibitors (oseltamivir) if within 48 hours of symptom onset 1
• COVID-19: Supportive care; antiviral therapy per current guidelines 1
• For viral pneumonia, focus on:
  • Oxygen therapy for hypoxemia 1, 3
  • Adequate hydration 3
  • Antipyretics for fever control (ibuprofen when temperature >38.5°C) 1

Duration of Therapy

• For uncomplicated bacterial pneumonia: 5-7 days is generally sufficient 4
• Shorter courses (3 days) of certain antibiotics like azithromycin may be as effective as longer courses for appropriate patients 5, 4
• Uncomplicated S. pneumoniae pneumonia is typically treated for 7-10 days 1
• Consider switching from IV to oral therapy when patients are clinically stable 3

Important Considerations and Pitfalls

• Azithromycin should not be used in patients with pneumonia who are inappropriate for oral therapy due to moderate to severe illness or significant risk factors 6
• Watch for QT prolongation with macrolides, especially in at-risk patients 6
• Monitor for Clostridium difficile-associated diarrhea with any antibiotic therapy 6
• Avoid first-generation cephalosporins, cefaclor, loracarbef, and trimethoprim/sulfamethoxazole if drug-resistant S. pneumoniae is suspected 1
• For empiric therapy of bacterial pneumonia, consider local antimicrobial resistance patterns 1
• Obtain cultures before starting antibiotics when possible, especially when concerned about multidrug-resistant pathogens 1
• If expanded therapy for resistant organisms is initiated, narrow therapy within 48 hours if cultures are negative and the patient is improving 1

Non-Pharmacologic Management

• Early mobilization for all patients to prevent complications 3
• Regular assessment of clinical stability (temperature, respiratory rate, blood pressure, oxygen saturation, mental status) 3
• Consider non-invasive ventilation for patients with hypoxemia or respiratory distress 3
• Follow-up chest radiograph 4-6 weeks after hospital discharge to establish a new baseline 3