What is the treatment for pneumonia?

Treatment for Pneumonia

For community-acquired pneumonia, the recommended first-line treatment is a combination of a β-lactam (amoxicillin 500-1000 mg PO every 8 hours) plus a macrolide (azithromycin 500 mg on day 1, followed by 250 mg daily for days 2-5). 1

Initial Antibiotic Selection

Outpatient Treatment

• Mild to moderate pneumonia (previously healthy patients):
  • First choice: Amoxicillin 500-1000 mg PO every 8 hours 1
  • Alternative for penicillin-allergic patients: Doxycycline 100 mg PO twice daily 1
  • For atypical pathogens: Add azithromycin 500 mg on day 1, then 250 mg daily for days 2-5 2

Inpatient Treatment

• Hospitalized patients:
  • IV combination therapy with β-lactam (ceftriaxone, ampicillin, or benzylpenicillin) plus a macrolide (clarithromycin or azithromycin) 1
  • For β-lactam intolerance: Respiratory fluoroquinolone (levofloxacin) 1

Special Considerations

• Ventilator-associated pneumonia (VAP):
  • Empiric therapy based on prior antibiotic exposure 3
  • Gram-positive cocci and H. influenzae are more common in patients without previous antibiotics 3
  • Non-fermentative gram-negative bacilli are associated with prior antibiotic use 3

Treatment Duration

• Standard duration:
  • Non-severe, uncomplicated pneumonia: 7 days 1
  • Severe pneumonia without identified pathogen: 10 days 1
  • Special cases (Legionella, staphylococcal, gram-negative): 14-21 days 1
  • Uncomplicated S. pneumoniae pneumonia: 7-10 days 3

Pathogen-Specific Considerations

Streptococcus pneumoniae

• Penicillin G remains the drug of choice for most S. pneumoniae infections in the United States 3
• Despite increasing in vitro resistance, clinical failures with β-lactams for pneumococcal pneumonia are rare 4
• Probability of cure ranges from 95% in uncomplicated infection to 50-80% with bacteremic disease 3

Atypical Pathogens

• For Mycoplasma pneumoniae or Chlamydia pneumoniae:
  • Macrolides (azithromycin, clarithromycin) or doxycycline 5
  • Treatment duration: 10-14 days 1
• For Legionella pneumophila:
  • Erythromycin 2-4g daily for at least 3 weeks 5
  • Alternatives: Respiratory fluoroquinolones or tetracyclines 5

Route of Administration

• Oral route preferred for non-severe pneumonia 1
• Switch from IV to oral therapy when:
  • Clinical improvement occurs
  • Temperature has been normal for 24 hours
  • No contraindications to oral therapy exist 1

Management of Treatment Failure

• If no improvement after 72 hours:
  • Review clinical history, examination, and investigation results
  • Consider additional investigations (repeat chest radiograph, CRP, WBC)
  • Consider changing antibiotics (add or substitute a macrolide) 1
• Possible causes of treatment failure:
  • Antimicrobial resistance
  • Unusual organism
  • Incorrect diagnosis 1

Important Caveats

• Vancomycin administration for MRSA VAP is associated with poor outcomes 3
• MRSA is not expected in the absence of prior antibiotic administration 3
• Antifungal therapy is not required even with Candida colonization 3
• Prolonging antibiotic treatment does not prevent recurrences 3

Monitoring and Follow-up

• Assess clinical response within 48-72 hours of initiating therapy 1
• Measure C-reactive protein on days 1 and 3/4, especially with unfavorable clinical parameters 1
• Arrange clinical review for all patients at around 6 weeks 1
• Perform chest radiograph at 6 weeks for patients with persistent symptoms or signs, or those at higher risk of underlying malignancy 1

By following this evidence-based approach to pneumonia treatment, focusing on appropriate antibiotic selection and duration based on severity and likely pathogens, clinicians can optimize outcomes in terms of morbidity, mortality, and quality of life.