Community Acquired Pneumonia

Question 1

Pathology

Answer 1

• Pneumonia acquired outside hospital/healthcare setting

Spread
- Respiratory = from host to host

Question 2

Cause

Answer 2

• Streptococcus pneumoniae
• Staphylococcus aureus
• Haemophilus influenzae
• Group A streptococci
• Influenza virus
• Respiratory syncytial virus (RSV)

Question 3

Risk factors

Answer 3

• Advanced age, lowered immunity, smoking and alcohol abuse, malnutrition and chronic lung disease

Question 4

Staging

Answer 4

1. Congestion (between days 1-2) = blood vessels and alveoli start filling with excess fluid
2. Red hepatization (between days 3-4) = exudate (contains RBCs, neutrophils, fibrin) starts filling airspaces, which solidifies them and a liver-like appearance
3. Grey hepatization (between days 5-7) = lungs remain firm but colour changes, the RBCs in exudate being to breakdown
4. Resolution (between day 8 to 3 weeks) = exudate digested by enzymes, ingested by macrophages and coughed up in sputum

Question 5

Complications

Answer 5

Meningitis, sepsis and pleural effusions

Question 6

Signs and symptoms

Answer 6

• High fever, cough, chest pain, tachypnea, tachycardia, muscle pain and fatigue
• Dulness on percussion

Question 7

Diagnosis

Answer 7

• chest X-ray = interstitial infiltrates; consolidation; may show pleural effusion

Lab results
- low oxygen saturation
- CBC: leuokocytosis

Organism identification
- Sputum and Gram stain
- Culture
- C-reactive protein test (CRP)
- Positive urine for S. pneumoniae

Question 8

Prevention

Answer 8

• 23-valent vaccine (Pneumovax) available against pneumococcus