Week 3 - Pathology of Respiratory Tract Infections

Question 1

What are some common URTI’s? (6)

Answer 1

coryza, sore throat syndrome, croup, laryngitis, sinusitis and acute epiglottitis

Question 2

What are 3 common LRTI’s?

Answer 2

Bronchitis, bronchiolitis, pneumonia

Question 3

What are 6 types of pneumonia?

Answer 3

CHIARA
- community acquired pneumonia
- hospital acquired pneumonia
- pneumonia in immunocompromised
- aspiration pneumonia
- recurrent pneumonia
- atypical pneumonia

Question 4

What 3 aspects does that macrophage-mucociliary escalator system include?

Answer 4

alveolar macrophages, mucociliary escalator and cough reflex

Question 5

What is bronchopneumonia vs lobar pneumonia?

Answer 5

bronchopneumonia affects patches throughout both lungs. Lobar pneumonia affects one or more lobes of the lungs

Question 6

What is characteristic of bronchopneumonia?

Answer 6

pus accumulates in the lungs and alveoli in patchy/spotty pattern throughout the lung

Question 7

How does pneumonia occur?

Answer 7

Microbe makes it past the resp. systems defence mechanisms and colonises the bronchioles or alveoli. This can infect lung tissue and cause an inflammatory response, causing an accumulation of neutrophils, exudate etc

Question 8

What can cause pneumonia?

Answer 8

Bacteria, viruses, fungi

Question 9

What are 3 common bacteria that cause pneumonia?

Answer 9

Staphylococcus aureus, streptococcus pneumoniae and haemophilus influenzae

Question 10

What is a common virus that causes pneumonia?

Answer 10

influenza

Question 11

What causes atypical pneumonia? why is it atypical?

Answer 11

bacteria with no cell wall. often cause vague symptoms like fatigue

Question 12

What bacteria causes the vast majority of lobar pneumonia?

Answer 12

streptococcus pneumoniae

Question 13

What is the pathogenesis of lobar pneumonia?

Answer 13

• bacteria invades lung.
• blood vessels and alveoli fill with fluid, causing pulmonary oedema.
• exudate of RBC’s, neutrophils and fibrin then fills alveoli and bronchi and make them more solid, like the liver.
• Then RBC’s disappear but neutrophils and fibrin persist and form grey solid lung.

Question 14

What is the process of resolution of pneumonia?

Answer 14

enzymes digest and macrophages ingest exudate, and waste is coughed up or drained via lymph

Question 15

What are 3 negative outcomes of pneumonia?

Answer 15

• Pleura becomes infected
• Organisation occurs leaving mass in lung
• Lung abscess occurs - necrosis

Question 16

What is empyema?

Answer 16

accumulation of pus in pleural space due to bacteria getting in. occurs after lobar pneumonia - not bronchopneumonia

Question 17

What is acute bronchitis caused by and features?

Answer 17

usually viral, 3 weeks or less. Bronchi becomes inflamed and swell and produce mucus, causing cough

Question 18

What is bronchiectasis?

Answer 18

abnormal dilatation of bronchi caused by severe infection. bronchi has abnormal cilia and a lot of mucus

Question 19

What causes bronchiectasis?

Answer 19

can be tuberculosis, cystic fibrosis

Question 20

What are 3 causes of aspiration pneumonia?

Answer 20

• Vomiting while laying down
• Lesion in oesophagus
• Neuromuscular disorder leading to uncoordinated movement between epiglottis and swallow - food inhaled

Question 21

What is the normal PaO2 and PaCO2?

Answer 21

PaO2 - 10.5-13.5kPa
PaCO2 - 4.8-6.0 kPa

Question 22

Why could an individual have reccuring lung infections? (4)

Answer 22

Immunocompromised, general lung disease, pulmonary damage, bronchial obstruction

Question 23

What is the PaO2 and PaCO2 in type 1 resp. failure??

Answer 23

PaO2 below 8.0kPa and PaCO2 normal or low

Question 24

What is the PaO2 and PaCO2 in type 2 resp. failure??

Answer 24

PaO2 low and PaCO2 above 6.5kPa - high

Question 25

What are the 2 main causes of type 1 respiratory failure?

Answer 25

ventilation perfusion mismatch and shunt

Question 26

In which patients does shunt mostly occur?

Answer 26

severe bronchopneumonia or lobar pneumonia

Question 27

What is shunt and why does it occur?

Answer 27

perfusion is greater than ventilation. Lobes or areas of lung are poorly ventilated due to “solid lung” or narrowing of airways. Deoxygenated blood returns to the heart

Question 28

What 2 diseases are large causes of ventilation perfusion mismatch?

Answer 28

bronchopneumonia and bronchitis

Question 29

Which bacteria (1) and viruses (4) commonly cause URTI?

Answer 29

bacteria - strep. pyogenes
viruses - influenza, parainfluenza, rhinovirus and Epstein-Barr virus