Treatment Approach for Pneumonia
For patients with community-acquired pneumonia (CAP), treatment should include a β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either azithromycin or a fluoroquinolone, with therapy duration of at least 5 days and until the patient is afebrile for 48-72 hours with no more than one sign of clinical instability. 1
Initial Assessment and Treatment Decisions
- Determine the appropriate treatment setting (outpatient vs. inpatient vs. ICU) based on severity of illness and risk factors 1
- For hospitalized patients, administer the first antibiotic dose while still in the emergency department 1
- Collect respiratory samples for culture before initiating antibiotics, but do not delay treatment to obtain cultures in unstable patients 1
- Test for COVID-19 and influenza when these viruses are circulating in the community 2
Antibiotic Selection
Inpatient (Non-ICU) Treatment:
- First-line therapy: β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either:
- For penicillin-allergic patients: respiratory fluoroquinolone plus aztreonam 1
ICU Treatment:
- For patients without Pseudomonas risk factors: same as inpatient regimen above 1
- For patients with Pseudomonas risk factors: antipneumococcal, antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either:
- Ciprofloxacin/levofloxacin (750mg) OR
- An aminoglycoside plus azithromycin OR
- An aminoglycoside plus antipneumococcal fluoroquinolone 1
- For suspected community-acquired MRSA: add vancomycin or linezolid 1
Special Considerations
- For suspected influenza, especially H5N1, add oseltamivir and target coverage for S. pneumoniae and S. aureus (common causes of secondary bacterial pneumonia) 1
- Azithromycin should not be used as monotherapy in patients who are inappropriate for oral therapy due to moderate-severe illness or risk factors (cystic fibrosis, nosocomial infections, bacteremia, hospitalization, elderly/debilitated patients, or significant underlying health problems) 3
- Patients with hypoxemia or respiratory distress should receive a cautious trial of noninvasive ventilation unless immediate intubation is required 1
- For patients with diffuse bilateral pneumonia or ARDS, use low-tidal-volume ventilation (6 cm³/kg of ideal body weight) 1
Duration of Therapy and Monitoring
- Treat for a minimum of 5 days (level I evidence) 1
- Continue antibiotics until patient is afebrile for 48-72 hours and has no more than one CAP-associated sign of clinical instability 1
- Longer therapy may be needed if:
- Initial therapy was not active against the identified pathogen
- Infection is complicated by extrapulmonary involvement (meningitis, endocarditis) 1
- Switch from IV to oral therapy when the patient:
- Is hemodynamically stable and clinically improving
- Can ingest medications
- Has normal gastrointestinal function 1
- Assess clinical response by day 2-3 (temperature, WBC, chest X-ray, oxygenation, sputum purulence, hemodynamic changes) 1
Pathogen-Directed Therapy
- Once the etiology is identified through reliable microbiological methods, direct therapy at the specific pathogen 1
- De-escalate broad-spectrum therapy based on culture results 1
- For severe CAP with persistent septic shock despite fluid resuscitation, consider drotrecogin alfa activated within 24 hours of admission 1
Common Pitfalls and Caveats
- Delay in antibiotic administration increases mortality; administer first dose in the ED 1
- Failure to recognize resistant pathogens can lead to inappropriate initial therapy and increased mortality 1
- When selecting antibiotics for patients who recently received antibiotics, choose an agent from a different class to avoid resistance 1
- Monitor for Clostridium difficile-associated diarrhea, which can occur up to two months after antibiotic use 3
- Be aware of QT prolongation risk with azithromycin, especially in elderly patients or those with cardiac risk factors 3
- Consider occult adrenal insufficiency in hypotensive, fluid-resuscitated patients with severe CAP 1