Community Acquired Pneumonia

Pneumonia is an infection of the lower respiratory airway/lung parenchyma by community acquired bacteria.

Most common agents:

Typical CAP: Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis.
Atypical CAP: Mycoplasma, Legionella, Chlamydia.

SYMPTOMS:

  • Cough
  • Fever
  • Malaise
  • Shortness of breath
  • Chest pain on inspiration
  • In atypical pneumonias the patient may have: headache, ear pain, diarrhea, rash

SIGNS:

  • Increased RR and HR
  • Cough
  • Crackles/Rales on Auscultation
  • Bronchial breathing
  • Egophony
  • Increased tactile fremitus
  • Dullness to percussion
  • Reduced breath sounds or Muffled sound (Pleural effusion)
  • In severe cases: hypotension, altered mental status, signs of imminent respiratory failure

TESTS TO CONSIDER ORDERING:

  • Chest X-Ray (usually consolidation in bacterial infections and diffuse infiltrates in viral infections)
  • CBC, CMP, C-Reactive protein, Procalcitonin
  • Arterial Blood Gases
  • Blood cultures
  • Sputum cultures
  • Urine Antigen for Legionella and Streptococcus
  • Bronchoalveolar Lavage
  • If pleural effusion: Diagnostic thoracentesis (pH, GRAM stain, LDH, protein, ADA)

DIAGNOSTIC CRITERIA:

Suggestive clinical features + Infiltrate on the X-Ray.

MANAGEMENT & TREATMENT:

Assess severity and decide for outpatient or inpatient treatment using one of the following scores:

CURB-65

PSI/PORT Score

Treatment:

Outpatient/Low risk/No comorbidities: Macrolide (azithromycin, clarithromycin).

Outpatient with Comorbidities: Fluoroquinolone (Moxifloxacin, Levofloxacin) OR Macrolide + Beta-lactam (Amoxacilin or Amoxacilin+Clavulonate).

Inpatient: Beta-lactam/Cephalosporine (Ceftriaxone) + Macrolide OR Fluoroquinolone.

Inpatient with Risk/Suspicion for MRSA: Add Vancomycin or Linezolid.

Inpatient with risk/suspicion for Pseudomonas: Antipseudomonal Beta-lactam (Piperacilin-Tazobactam, Cefepime or Carbapenens) + Quinolone OR Antipseudomonal Beta-lactam + Aminoglicoside + Macrolide OR Aztreonam + Aminoglicoside + Quinolone.

Manage septic patients according to the sepsis protocol.

DISEASES THAT MAY PRESENT WITH SIMILAR SIGNS AND SYMPTOMS:

  • Viral pneumonia
  • Fungal pneumonia
  • Tuberculosis
  • Lung vasculitis

SOURCES & REFERENCES, RESOURCES AND FURTHER READING:

  1. Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults
  2. CURB-65 Pneumonia Severity Score
  3. The role of procalcitonin in adult patients with community-acquired pneumonia–a systematic review.
  4.  The Pneumonia Severity Index: A Decade after the Initial Derivation and Validation
  5.  Community Acquired Pneumonia in Adults Guideline
  6.  Pneumonia in adults: Diagnosis and Management
  7.  Community-Acquired Pneumonia
  8. CURB-65 – Calculator
  9. PSI/PORT Score: Pneumonia Severity Index for CAP – Calculator