Pathology of parenchymal lung disease Flashcards
Examples of mechanical defence mechanisms
Ciliated epithelium
Mucus
Cough (damaged by neuromuscular problem- strokes)
Examples of immunological defence mechanisms
IgA and antimicrobials in mucus
Resident alveolar macrophages and dendritic cells
Innate/ adaptive immune responses
Describe the gas exchange surface
Thin
Type 2 pneumocytes/ epithelium differentiate to type 1, produce surfactant
Type 1 pneumocytes- gas exchange
Vessels and cells
What is the parenchyma?
The parts of the lungs involved in gas transfer including the alveoli, interstitium, blood vessels, bronchi and bronchioles
- Respiratory bronchiole
- Terminal bronchiole
- Alveolar rings, ducts, septum
How might pneumonia present?
-Shortness of breath
-Cough
-Haemoptysis (coughing up blood)
-Pyrexia (temperature)
=Elevated neutrophils
=Right basal crepitations and consolidation
Describe pneumonia
- Greatest cause of deaths due to infection in the developed world
- 15% of all deaths of children under 5
- Caused by range of pathogens= bacteria, fungi, virus
What are the categories of pneumonia?
-Community acquired
-Hospital acquired
-Health care associated
-Aspiration associated
-Immunocompromised host
-Necrotising/ abscess formation
=Resistance
What pathogens are associated with Community acquired pneumonia?
- Streptococcal pneumoniae
- Haemophilus influenzae
- Moraxella catarrhalis
- Staphylococcus aureus
- Klebsiella pneumoniae/ Pseudomonas aeruginosa
- Mycoplasma pneumoniae
What are the pathogens associated with hospital acquired/ health care associated pneumonia?
-Gram negative rods= Enterobacteriaceae, Pseudomonas
-Staph aureus (usually methicillin resistant)
=more immunosuppressed, at least 48 hours prior to symptom onset
What pathogens are associated with aspiration pneumonia?
Anaerobic oral flora mixed with aerobic bacteria
No control over larynx
What pathogens are associated with Pneumonia in the immunocompromised host?
- Cytomegalovirus (organ transplant-liver)
- Pneumocytis jiroveci (PCP)
- Mycobacterium avium-intracellulare
- Invasive aspergillosis
- Invasive candidiasis
- Unusual bacterial, virus and fungal organisms
What pathogens are associated with necrotising/ abscess formation?
Anaerobes, S. aureus, Klebsiella, S. pyogenes
Describe the cellular response to infection
- Neutrophils= chemotaxis, degranulation, reactive oxygen species, extracellular traps, phagocytosis
- Macrophages(alveolar resident recruit)= cytokine and chemokines, phagocytosis (bacteria and dead cells), antimicrobial peptides, resolution (also involves T cells, dendritic cells and epithelial cells)
What is the clinical presentation of pneumonia?
- Cough
- Sputum= stimulates goblet cells so production of mucus
- Pyrexia
- Pleuritic chest pain= irritated pleura (rubbing)
- Haemoptysis= vasodilation, rupture of small blood vessels
- Dyspnoea
- Hypoxia= not effective gas exchange, pus filled alveoli
What are the types of pneumonia?
- Bronchopneumonia
- Lobar pneumonia
Describe the appearance of bronchopneumonia
- Most common pattern
- Patchy consolidated areas of acute suppurative inflammation
- Often elderly with risk factors (cancer, heart failure, renal failure, stroke, COPD)
Describe the appearance of lobar pneumonia
- Rust coloured sputum
- S. pneumoniae
- Consolidation of a large portion of a lobe or of an entire lobe
What are the general risk factors for pneumonia?
- Chronic disease
- Immunologic deficiency
- Immunosuppressive agents
- Leukopenia