Pathology of Respiratory Tract Infection (Pulmonary Infection)

Question 1

What are the factors that determine the effect an infection will have?

Answer 1

The micro-organism pathogenicity, patient’s ability to resist infection and the population at risk

Question 2

What is the difference between primary, facultative and opportunistic pathogens?

Answer 2

Primary - would infect anyone
Facultative - need a pre-existing pathology
Opportunistic - need a reduction in the host’s ability to fight infection (immunosuppressed patients)

Question 3

What effects a patients capacity to resist an infection?

Answer 3

Defence mechanisms. age, health and pathologies

Question 4

What defence mechanisms does the respiratory tract have?

Answer 4

-Macrophage-mucociliary escalator
-Immune System
-Respiratory Tract Secretions
‘Filter’ of Upper Respiratory Tract
-Alveolar macrophages
-Cough reflex

Question 5

Is the lower respiratory tract a sterile or non-sterile site?

Answer 5

Sterile

Question 6

What are the two ways that particles can be cleared from the lungs?

Answer 6

Lymph nodes and the muco-ciliary escalator

Question 7

What is the leading cause of death in patients with influenza?

Answer 7

Secondary bacterial infection

Question 8

What is community acquired pneumonia?

Answer 8

The pneumonia is not acquired in a hospital setting

Question 9

What is nosocomial pneumonia?

Answer 9

Pneumonia acquired in a hospital - micro-organism is much more likely to be resistant to antibiotics

Question 10

What is atypical pneumonia?

Answer 10

Pneumonia caused by a rare or unusual organism

Question 11

What is aspiration pneumonia?

Answer 11

Pneumonia secondary to inhaling gastric contents - quite common

Question 12

What would recurrent pneumonia suggest?

Answer 12

That something is very wrong - especially if it always occurs in the same part of the lung

Question 13

What is hypostatic pneumonia?

Answer 13

Pneumonia caused by a build up of secretions in the lung - common in the elderly and those who are bedridden etc.

Question 14

What are the complications that can arise from pneumonia?

Answer 14

Pleurisy, pleural effusion, empyema, organisation, lung abscess and bronchiectasis

Question 15

What is bronchiectasis?

Answer 15

Pathological dilatation of bronchi due to: severe infection, recurrent infection, proximal bronchial obstruction and lung parenchymal destruction

Question 16

What are the signs and symptoms of bronchiectasis?

Answer 16

Cough, sputum, haemoptysis, course crackles and clubbing

Question 17

What is the treatment of bronchiectasis?

Answer 17

Postural drainage, antibiotics and surgery

Question 18

Name the aetiological classification of pneumonia

Answer 18

• Community acquired
• Hospital acquired
• Pneumonia in the immunocompromised
• Atypical
• Aspiration
• Recurrent

Question 19

Name the features of bronchopneumonia

Answer 19

• Bilateral
• Patchy basal opacification
• Focal nature of consolidation

Question 20

What are the potential causes of recurrent lung infection?

Answer 20

• Local bronchial obstruction (tumour, foreign body etc.)
• Local pulmonary damage (bronchiectasis)
• Generalised lung disease (CF, COPD)
• Non-respiratory disease (immunocompromised, aspiration etc.)

Question 21

Name some of the potential causes of aspiration pneumonia

Answer 21

• Vomiting
• Oesophageal lesion
• Obstetric anaesthesia
• Neuromuscular disorders
• Sedation

Question 22

Name the potential opportunistic infections

Answer 22

• Low grade bacterial pathogens
• CMV
• Pneumocystis jirovecii
• Other fungi and yeasts

Question 23

What are the features of Type 1 respiratory failure

Answer 23

• PaO2 < 8 kPa

- PaCO2 normal or low

Question 24

What are the features of Type 2 respiratory failure?

Answer 24

• PaCO2 > 6.5 kPa

- PaO2 usually low

Question 25

Name the four abnormal states associated with hypoxaemia

Answer 25

• Ventilation/perfusion imbalance
• Diffusion impairment
• Alveolar hypoventilation
• Shunt

Question 26

What is shunt?

Answer 26

• Blood passing from the right to the left side of the heart without contacting ventilated alveoli
• Normal is 2-4%
• Pathological in AV malformations, congenital heart disease and pulmonary disease