21. Acute Pulmonary infections

• Pneumonia - defined as infection induced inflammation lung parenchyma
• Any lung damage = higher risk for pneumonia caused by microorganism
• S pneumoniae common cause community acquired pneumonia
• Community acquired pneumonia (CAP)

  • Infectious agent contracted in general population
• Diagnosis of CAP (Community acquired pneumonia) - can still reached up to 48 hours post-admission to hospital
• Hospital acquired pneumonia (HAP) - Pneumonia acquired >48 hours post admission
• Lobar or bronchopneumonia will result in airspace filling with purulent exudate due to neutrophil

  
• in pneumonia, the bacteria spread from one alveoli to another by

  • spread via interalveolar connection
  • pore of Kohn
  • canals of Lambert
  • channel of martin
• in pneumonia, alveolar airspaces will be filled with other substance (not air)

  • leading to lung becoming opacify and consolidate
• What is the most common cause of consolidation in imaging?

  pneumonia
• Lobar pneumonia - homogenous suppurative consolidation of lung lobes

  
• Lobar pneumonia - spread of infection is across segmental boundaries
• What is the most common cause of lobar pneumonia?

  s pneumoniae
• Bronchopneumonia - patchy area of consolidation

  • patch is separated by normal lung parenchyma
• Bronchopneumonia there is neutrophil infiltration
• Patchy pattern of pneumonia can progress into lobar
• Pneumonia - risk

  • extrinsic - microorganism
  • intrinsic - due to host behavior
  • age
  • smoking
• Community acquired pneumonia (CAP) - follow upper respiratory tract viral infection
• Community acquired pneumonia (CAP) - most presenting symptoms is

  • productive cough with mucopurulent sputum made by neutrophil
• Community acquired pneumonia (CAP) - most common people affected are

  • immunocompromised
  • elderly
• What color sputum do you get in lobar pneumonia by (pneumoniae)?

  rust color
• Hospital-acquired pneumonia (HAP) is commonly due to aspiration

  • colonized upper to lower respiratory tract
• H. influenzae

  • consider normal respiratory flora
  • associated with hospital acquired pneumonia
  • colonize upper respiratory tract - nasopharynx
• S. aureus associated with

  • abscess formation
  • empyema
• S. aureus affects - IV drug users and IC people
• Pseudomonas

  • ventilator
  • smells like grapes
• Atypical pneumonia - pts will come in with a low grade fever

  • walking pneumonia
• Legionella

  • water system or AC
• Hospital-acquired pneumonia (HAP) - infectious agent contracted in medical/healthcare facility is >48 hours
• Aspiration pneumonitis/pneumonia is related to ARDS
• Empyema - Purulent inflammatory collections within a pre-existing body cavity
• Empyema - Drainage to prevent fibrosis
• Viral pneumonia may leave patients with residual disability from interstitial fibrosis
• respiratory viruses tend to multiply in upper airway epithelium
• Most common viral cause of pneumonia?

  Influenza
• Leading cause of pediatric respiratory infection?

  Respiratory syncytial virus (RSV)
• Respiratory syncytial virus (RSV) - causes Coryza (inflammation of a mucous membrane)
• COVID can cause Diffuse alveolar damage