Initial Approach to Treating Pneumonia
The initial approach to treating pneumonia requires immediate empiric antimicrobial therapy based on severity assessment, with treatment selection determined by the patient's risk of mortality and appropriate care setting (outpatient, hospital ward, or ICU). 1
Step 1: Assess Severity and Determine Treatment Setting
Severity assessment is crucial for determining:
- Appropriate treatment setting (outpatient, hospital ward, or ICU)
- Empiric antibiotic selection
- Intensity of care needed
Tools to guide decision-making:
- PSI (Pneumonia Severity Index) - preferred for outpatient vs. inpatient decisions 1
- CURB-65 - simpler alternative but with less evidence 1
- 2007 IDSA/ATS severe CAP criteria - for ICU admission decisions 1
Caution: Patients transferred to ICU after initial ward admission have higher mortality than those directly admitted to ICU from the emergency department 1
Step 2: Initiate Empiric Antibiotic Therapy
For Outpatients:
Healthy adults without comorbidities:
- Amoxicillin 1g three times daily (first choice) 1
- Doxycycline 100mg twice daily 1
- Macrolide (azithromycin 500mg on first day then 250mg daily or clarithromycin 500mg twice daily) - only in areas with pneumococcal resistance to macrolides <25% 1, 2
Adults with comorbidities (chronic heart/lung/liver/renal disease, diabetes, alcoholism, malignancy, asplenia):
- Combination therapy:
- Amoxicillin/clavulanate (500mg/125mg three times daily or 875mg/125mg twice daily) OR cephalosporin (cefpodoxime 200mg twice daily or cefuroxime 500mg twice daily)
- PLUS macrolide or doxycycline 1
For Hospitalized Patients (non-ICU):
Options include (in alphabetical order):
- Aminopenicillin ± macrolide
- Aminopenicillin/β-lactamase inhibitor ± macrolide
- Non-antipseudomonal cephalosporin (cefotaxime or ceftriaxone) ± macrolide
- Levofloxacin
- Moxifloxacin
- Penicillin G ± macrolide 1
Important: β-lactam/macrolide combination therapy (e.g., ceftriaxone with azithromycin) is recommended for hospitalized patients without risk factors for resistant bacteria 3
For ICU Patients:
Without risk factors for Pseudomonas aeruginosa:
- Non-antipseudomonal cephalosporin III + macrolide OR
- Moxifloxacin or levofloxacin ± non-antipseudomonal cephalosporin III 1
With risk factors for Pseudomonas aeruginosa:
- Antipseudomonal cephalosporin OR acylureidopenicillin/β-lactamase inhibitor OR carbapenem (meropenem preferred)
- PLUS ciprofloxacin OR macrolide + aminoglycoside 1
Step 3: Route of Administration and Timing
- Timing: Antibiotic treatment should be initiated immediately after diagnosis of CAP 1
- Route:
Step 4: Duration of Therapy
- Treatment duration should generally not exceed 8 days in responding patients 1
- Biomarkers, particularly procalcitonin (PCT), may guide shorter treatment duration 1
- Minimum of 3 days for hospitalized patients with bacterial CAP 3
Special Considerations
Diagnostic Testing
- Test for COVID-19 and influenza during seasons when these viruses are common 3
- Consider urinary antigen testing for Legionella in severe cases or when epidemiologically suspected 1
- Molecular tests for detection of S. pneumoniae may be valuable in patients who have already started antibiotics 1
Adjunctive Therapies
- Early mobilization for all patients 1
- Low molecular weight heparin for patients with acute respiratory failure 1
- Consider systemic corticosteroids within 24 hours for severe CAP (may reduce 28-day mortality) 3
- Non-invasive ventilation can be considered, particularly in patients with COPD and ARDS 1
Common Pitfall: Delaying antibiotic administration after diagnosis increases mortality. Antibiotics should be initiated immediately after diagnosis, especially in patients with septic shock 1
Caution: Steroids are not routinely recommended in the treatment of pneumonia except in severe cases 1, 3
By following this algorithmic approach based on severity assessment and patient risk factors, clinicians can optimize the initial management of pneumonia to reduce morbidity and mortality.