Pathology of Respiratory Tract Infections

Question 1

What are the different types of upper respiratory tract infections?

Answer 1

• coryza (common cold)
• sore throat syndrome
• acute laryngotraceobronchitis (croup)
• laryngitis
• sinusitis
• acute epiglottis

Question 2

What causes acute epiglottitis?

Answer 2

• haemophilus influenzas (type b - Hib)
• group A beta-haemolytic Streptococci
• rarely caused by Parainfluenza virus type 4 but other viruses may also be responsible

Question 3

What are the different types of lower respiratory tract infections?

Answer 3

• bronchitis
• bronchiolitis
• pneumonia
• consequences
• possible complications

Question 4

What are the defence mechanisms of the respiratory tract?

Answer 4

• macrophage-mucociliary escalator system
• general immune system (humoral and cellular immunity)
• respiratory tract secretions
• upper respiratory tract as a ‘filter’

(failure in any of these systems increases the risk of respiratory tract infection)

Question 5

What are the components of the macrophage-mucociliary escalator system?

Answer 5

• alveolar macrophages
• mucociliary escalator
• cough reflex

Question 6

Is the normal lower respiratory tract sterile or non-sterile?

Answer 6

Sterile

Question 7

What are the different classifications of pneumonia?

Answer 7

• anatomical
• aetiological (circumstances)
• microbiological

Question 8

What are the different aetiological classifications of pneumonia?

Answer 8

• community acquired pneumonia
• hospital acquired (nosocomial) pneumonia
• pneumonia in the immunocompromised
• atypical pneumonia
• aspiration pneumonia
• recurrent pneumonia

Question 9

What are the different patterns of pneumonia?

Answer 9

• bronchopneumonia
• segmental
• lobar
• hypostatic
• aspiration
• obstructive, retention, endogenous lipid

Question 10

What are the outcomes/complications or pneumonia?

Answer 10

• most resolve
• pleurisy, pleural effusion and empyema
• organisation (mass lesion, COP pr cryptogenic organising pneumonia)
• lung abscess
• bronchiectasis
• pneumonia is still a potentially fatal disease

Question 11

What causes lung abscess’?

Answer 11

• obstructed bronchus: tumour
• aspiration
• particular organism (staph aureus, some pneumococci, klebsiella)
• metastatic in pyaemia
• necrotic lung

Question 12

What is bronchiectasis?

Answer 12

Pathological dilation of Bronchi due to:
- severe infective episode
- recurrent infections —> manny causes
- proximal bronchial obstruction
- lung parenchymal destruction

Question 13

What are the characteristics of bronchiectasis?

Answer 13

• cough
• abundant purulent foul sputum
• haemoptysis
• signs of chronic infection
• coarse crackles
• clubbing

Question 14

How do you help bronchiectasis?

Answer 14

• thin section CT (previously bronchography)
• postural drainage
• antibiotics
• surgery

Question 15

How are the bodies defences failing in local bronchial obstruction?

Answer 15

• tumour
• foreign body

Question 16

How are the bodies defences failing in local pulmonary damage?

Answer 16

• bronchiectasis

Question 17

How are the bodies defences failing in generalised lung disease?

Answer 17

• cystic fibrosis
• COPD

Question 18

How are the bodies defences failing in non-respiratory disease?

Answer 18

• immunocompromised (HIV, other?)
• aspiration

Question 19

What are the causes of aspiration pneumonia?

Answer 19

• vomiting
• oesophageal lesion
• obstetric anaesthesia
• neuromuscular disorders
• sedation

Question 20

What are opportunistic infections?

Answer 20

Infections caused by organisms not normally capable of producing disease in patients with intact lung defences.

Question 21

What are different types of opportunistic pathogens?

Answer 21

• low grade bacterial pathogens
• CMV
• pneumocystis jirovecii
• other fungi and yeasts