Treatment of Bacterial Pneumonia
The recommended first-line treatment for bacterial pneumonia is a β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either azithromycin or a respiratory fluoroquinolone (levofloxacin or moxifloxacin). 1, 2
Outpatient Treatment
For patients with mild to moderate community-acquired pneumonia (CAP) who can be treated as outpatients:
First-line therapy:
For penicillin-allergic patients:
Note: Macrolide monotherapy is no longer recommended due to increasing pneumococcal resistance rates 1
Inpatient (Non-ICU) Treatment
For patients requiring hospitalization but not ICU care:
Standard regimen:
For penicillin-allergic patients:
- IV respiratory fluoroquinolone (moxifloxacin or levofloxacin 750 mg/day) 1
ICU Treatment
For patients with severe pneumonia requiring ICU admission:
Standard regimen:
- IV β-lactam (ceftriaxone, cefotaxime, or ampicillin-sulbactam) plus either IV azithromycin or an IV respiratory fluoroquinolone 1
For penicillin-allergic patients:
- Aztreonam plus an IV respiratory fluoroquinolone 1
Special Considerations
Pseudomonas aeruginosa Risk
If risk factors for Pseudomonas infection are present:
- Antipneumococcal, antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either ciprofloxacin or levofloxacin (750mg) 1
- OR antipneumococcal, antipseudomonal β-lactam plus an aminoglycoside and azithromycin 1
- OR antipneumococcal, antipseudomonal β-lactam plus an aminoglycoside and an antipneumococcal fluoroquinolone 1
MRSA Risk
If risk factors for methicillin-resistant Staphylococcus aureus (MRSA) are present:
- Add vancomycin or linezolid to the standard regimen 1
Pathogen-Directed Therapy
Once the causative pathogen is identified through reliable microbiological methods:
- Adjust therapy to target the specific pathogen 1
- For Streptococcus pneumoniae: β-lactams for penicillin-susceptible strains; levofloxacin, high-dose amoxicillin, or ceftriaxone for resistant strains 2
- For Legionella: Levofloxacin, moxifloxacin, or azithromycin 2
- For Mycoplasma or Chlamydophila: Doxycycline, macrolide, or fluoroquinolone 2
Duration of Therapy
- Minimum duration: 5 days 1
- Patient should be afebrile for 48-72 hours and have no more than one CAP-associated sign of clinical instability before discontinuing therapy 1
- Longer duration (10-14 days) may be needed for:
Monitoring Response
- Clinical response should be assessed within 48-72 hours of initiating therapy 2
- If no improvement after 72 hours, reevaluate diagnosis and consider alternative pathogens or complications 2
- Switch from IV to oral therapy when the patient is hemodynamically stable, improving clinically, able to ingest medications, and has a normally functioning GI tract 1
Common Pitfalls to Avoid
Macrolide monotherapy: Not recommended due to increasing resistance rates 1
Fluoroquinolone use in TB-suspected cases: Use fluoroquinolones with caution in patients with suspected tuberculosis, as they may delay diagnosis and proper treatment of TB 1
Inadequate duration: Stopping antibiotics too early can lead to treatment failure or relapse
Failure to adjust therapy: Not modifying treatment based on culture results when available
Overlooking special pathogens: Failing to consider and cover for MRSA or Pseudomonas when risk factors are present
The evidence strongly supports combination therapy with a β-lactam plus either a macrolide or fluoroquinolone for hospitalized patients with bacterial pneumonia to ensure adequate coverage of typical and atypical pathogens, with adjustments based on specific risk factors and identified pathogens.