Pneumonia: Classifications and Causes

Pneumonia

• An infection of the lungs that impacts one or both lungs
• Air sacs (alveoli) fill with fluid or pus

Classifications

• Anatomical/Histological
  • Lobar: Affects a single lobe
  • Bronchopneumonia (Lobular): Affects patchy areas, multiple lobes
  • Interstitial (Atypical): Impacts the interstitium
• Etiology:
  • Bacterial: Common causes include Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa
  • Viral: Influenza A and B, rhinovirus, human metapneumovirus, respiratory syncytial virus (RSV), parainfluenza, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), and adenovirus
  • Fungal, Atypical, Parasitic, Aspiration
• Where the infection was acquired:
  • Community-acquired pneumonia (CAP): Symptoms develop prior to or 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 and up to 48 hours after extubation.
  • Aspiration Pneumonia: Occurs when food or other substances enter the lungs.

Community-Acquired Pneumonia (CAP)

• Leading cause of death among infectious diseases
• Only 38% of cases have identified pathogens
• Risk Factors:
  • Smoking
  • Alcohol Consumption
  • Household size
  • Comorbidities
  • Age (as cough and gag reflexes decrease with age)
• 10-15% of CAP cases are polymicrobial
• Atypical Microorganisms:
  • Mycoplasma pneumoniae
  • Chlamydophila pneumoniae
  • Legionella species
• S. aureus pneumonia can complicate influenza virus infection.

This quiz covers the basics of pneumonia, including its types, classifications, and causes. Understand the differences between lobar and bronchopneumonia, as well as the various etiological factors, both bacterial and viral. Test your knowledge on community-acquired and hospital-acquired pneumonia.