Initial Treatment for Pneumonia
The initial empiric antibiotic therapy for pneumonia should be based on the patient's risk factors, severity of illness, and treatment setting, with amoxicillin as first-line therapy for community-acquired pneumonia in outpatients and a β-lactam plus a macrolide for hospitalized patients. 1
Treatment Algorithm Based on Patient Setting
Outpatient Treatment
- For previously healthy adults with no risk factors for drug-resistant pathogens, a macrolide (e.g., azithromycin) is recommended as first-line therapy 1, 2
- Amoxicillin 1 g every 8 hours is an alternative first-line therapy for outpatients without comorbidities 2
- Doxycycline 100 mg twice daily can also be used as an alternative first-line option 2
- For outpatients with comorbidities or recent antibiotic use, a respiratory fluoroquinolone (e.g., levofloxacin, moxifloxacin) or a β-lactam plus a macrolide is recommended 1, 2
Hospitalized Non-ICU Patients
- The standard regimen is a β-lactam (e.g., ceftriaxone) plus a macrolide (e.g., azithromycin) 1, 2
- A respiratory fluoroquinolone alone (levofloxacin or moxifloxacin) is an acceptable alternative 1, 2
- Antibiotics should be initiated immediately after diagnosis of pneumonia, as delays in appropriate therapy are associated with increased mortality 3, 1
Severe CAP/ICU Treatment
- For patients without risk factors for Pseudomonas, use a β-lactam plus either a macrolide or a respiratory fluoroquinolone 1, 2
- For patients with risk factors for Pseudomonas, use an antipseudomonal β-lactam (cefepime, ceftazidime, piperacillin-tazobactam, imipenem, or meropenem) plus either ciprofloxacin/levofloxacin or an aminoglycoside plus azithromycin 3, 2
Hospital-Acquired Pneumonia (HAP) and Ventilator-Associated Pneumonia (VAP)
- Initial empiric therapy should cover likely pathogens based on local surveillance and susceptibility data 3
- For patients with risk factors for multidrug-resistant (MDR) organisms, broad-spectrum antibiotics are recommended 3
- Empiric therapy should not be delayed for diagnostic studies in clinically unstable patients 3
Duration of Treatment
- The minimum duration of therapy is 5 days for most patients with community-acquired pneumonia 1, 2
- The patient should be afebrile for 48-72 hours and have no more than one sign of clinical instability before discontinuing therapy 1, 2
- For hospital-acquired pneumonia, treatment typically ranges from 7-14 days depending on the pathogen and clinical response 3
Special Considerations
Pathogen-Directed Therapy
- Once the etiology of pneumonia has been identified, antimicrobial therapy should be directed at that specific pathogen 1, 2
- For Legionella spp., use levofloxacin, moxifloxacin, or a macrolide (preferably azithromycin) 1, 4
- For atypical pathogens (Mycoplasma, Chlamydophila), macrolides, doxycycline, or respiratory fluoroquinolones are recommended 1, 4
Risk Factors for MDR Pathogens
- Prior hospitalization within 90 days 3
- Antibiotic therapy within the previous 90 days 3
- Immunosuppression 3
- Healthcare-associated pneumonia (HCAP) 3
- Mechanical ventilation for ≥5 days 3
Common Pitfalls and Caveats
- Delaying antibiotic administration is associated with increased mortality, especially in severe cases 3, 1
- Overreliance on fluoroquinolones can lead to resistance; they should be reserved for patients with β-lactam allergies or when specifically indicated 2, 5
- Blood cultures have limited utility in unselected patients with community-acquired pneumonia (positive in only 6-11% of cases) but may be valuable in severe pneumonia 3, 6
- Inadequate coverage for atypical pathogens should be avoided 1, 2
- Failure to adjust therapy based on culture results can lead to unnecessary prolonged therapy 1, 2
- QT prolongation is a risk with macrolides and fluoroquinolones, particularly in elderly patients or those with cardiac risk factors 5, 7