L.18 Pneumonia

Question 1

What is the microbiome in the airways

Answer 1

The airway (oropharanyx) is a microbiome for bacteria, viruses and fungi. Healthy ones with variety of organisms protect against disease. In disease it becomes less organisms and diversity, with pathogenic bacteria

Question 2

What are the defence mechanisms of the upper airways

Answer 2

• Effective coordinated swallowing mechanism
• Protection of lower airway by epiglottis and glottis
• Nose
• Cough & Sneeze - clearing mucus: MCC

Question 3

What are the microbiological insult to upper airways

Answer 3

• How many organisms: dependent on volume of aspiration, and how many present : eg. presence of gingivial
• Virulence of organism
• Particles setting in different parts depending on size: >10 um in nasal cavity, 5-10 um in trachea/ main bronchi

Question 4

What is the role of airway mucus

Answer 4

• Physical barrier, dilutes chemicals (oxidants and proteases), and Absorbs gases.
• Trapping particles which is removed by Mucocilliary escalator
• Binds water and hydrates
• Contains antimicrobial substances eg. defensin

Question 5

What is the composition of mucus in the upper airways and how are they affected by disease, and what is treatment

Answer 5

Made of water, ions and glycoproteins, most importantly
- Mucins: multimers that have different dominance in different diseases. In inflam and ROS there are increased disulfide bonds changing from watery to sticky consistency.
Treated by mucolytics which break disulfide bonds.
Saline also helps to reduce ionic bonds
-Antibacterial peptides: defensins, lysozymes.
In disease DNA from neutrophils is there which also makes sticky. Treated by recombinant human DNA which breaks down DNA.

Question 6

How does the mucocilliary escalator work

Answer 6

• Cilia have a coordinated effective and recovery stroke by intracellular signalling.
• Cilia sit in sol layer under mucus which is produced by club cells and epithelial cells. The height is important because cilia recover in it and it hydrates the mucus. This is determined by the cAMP gated Cl- ion channel out of the epithelial cell.

Question 7

What is the consequence of CF

Answer 7

Decreased pericilliary (sol) layer which increases viscosity and solid content in the mucus. Decreases ciliary function, beat frequency and structural damage to cilia. This leads to chronic infection, inflammation of the airways.

Question 8

How does cough work

Answer 8

It develops high intrathoracic pressures with sudden release which generates high linear flow velocity.
Excess mucus (normal is too thin) and trapped material and removed by sheer forces.

Question 9

What are the defence mechanisms in the lung periphery (past 16th generation; no MCC, cough)

Answer 9

• Alveolar macrophage: phagocyte, process antigens, immuno-regulation
• Bronchus associated Lymphoid tissue
• leukocyte recruited from pulmonary capillary
• Immunoglobulins

Question 10

What happens when bacteria in the alveolus and how does this contribute to macroscopic look of pneumonia

Answer 10

1. Bacteria in alveolus multiply as alveolar macrophage migrates to site of infection
2. Neutrophils migrate via chemotaxis towards the infection and capillaries leak exudate into the interstitium

Lungs are filled up with blood: red hepatization

Question 11

What are the risk factors for pneumonia

Answer 11

• old Age: reduced innate immunity- doesn’t need fever
• advanced dementia: changes in swallowing to protect upper airway
• rest homes/ hospital; increased colonisation of organisms; poor dental hygiene
• muscle weakness: impaired cough
• smoker: more likely to have chronic bronchitis, stickier mucus, impaired ciliary clearance