Pneumonia Classifications and Types

Study Notes

Pneumonia

Pneumonia is an infection of the lungs, specifically the air sacs (alveoli) which fill with fluid or pus
Pneumonia can affect one or both lungs

Pneumonia Classifications

Pneumonia is classified into multiple types including:

Anatomy/Histology:

  - Lobar pneumonia: Affecting a single lobe of the lung
  - Bronchopneumonia: Patchy areas of multiple lobes and bronchioles
  - Interstitial pneumonia: Affecting the interstitium of the lung

Etiology:

  - Bacterial
  - Viral
  - Fungal
  - Atypical
  - Parasitic
  - Aspiration

Acquired location:

  - Community-acquired pneumonia (CAP): Symptoms develop within 48 hours of hospital admission
  - Hospital-acquired pneumonia (HAP): Symptoms develop after 48 hours of hospital admission
  - Ventilator-associated pneumonia (VAP): Symptoms develop within 48 hours of intubation or after 48 hours of extubation
  - Aspiration pneumonia: Infection from food or foreign material entering the lungs

CAP - Community Acquired Pneumonia

Leading cause of death in infectious diseases
Only 38% of patients are reported back with the pathogens
Risk factors:
- Smoking
- Alcohol consumption
- Household size
- Comorbidities
- Age (cough and gag reflex?)
10-15% of CAP cases are polymicrobial
Typical bacteria:
- Streptococcus pneumoniae (S pneumoniae)
- Haemophilus influenzae (H influenza)
- Staphylococcus aureus (S aureus)
- Klebsiella pneumoniae (K pneumonia)
- Pseudomona aeruginosa (P aeruginese)
Atypical microorganism:
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
- Legionella species
- Respiratory viruses
  - Influenza A and B
  - Rhinovirus
  - Human metapneumovirus
  - Respiratory syncytial virus (RSV)
  - Parainfluenza
  - Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)
  - Adenovirus
S.aureus pneumonia is known to complicate influenza virus infection