Tuberculosis - aetiology, pathogenesis and pathological features Flashcards Preview

Pathology-IMED4111 > Tuberculosis - aetiology, pathogenesis and pathological features > Flashcards

Flashcards in Tuberculosis - aetiology, pathogenesis and pathological features Deck (14):
1

Describe the sequence of events in cells/tissues after infection with TB

Macrophage ingestion
Spread to lymph nodes
Bacteraemia - organisms divides unchecked
-Inhibition of lysosomal fusion

2

What are the sequences of events in TB infection, starting with inhalation

-Inhalation of the bacilli
-Implants in lower part of upper lobe of the lung, or upper part of the lower lobe
-Develops a Ghon focus, which undergoes central caseous necrosis
-Bacilli drain to regional lymph nodes, that also caseate, forming more Ghon processes
-At this stage, there is haematogenous and lymphatic dissemination
-Ghon complexes undergo fibrosis and form a Ranke complex

3

What are clinical manifestations of primary TB?

Progressive lung disease with:
-Malaise, weight loss
-Fever, night sweats
-Cough, sputum
-Pleuritic pain

- Resembles acute bacterial pneumonia in some cases

4

What % of TB deaths occur in low income countries?

90%

5

How many times more likely are you to get TB in Australia if you are Aboriginal, compared to non-aboriginal?

8x

6

Is Tb aerobic or anaerobic?

Aerobic

7

Describe some TB testing

- Sputum, tissue ZNs stain, fluorescent staining
-Culture
-NAT
-Mantoux testing
-Quantiferon assay

8

What are 3 virulence factors of Mycobacterium tuberculosis?

-Cord factor - a glycolipid in the cell wall
-Inhibition of phagolysosome formation
-Suppression of T-cell function
-Protection against complement activated killing

9

What does secondary TB infection look like clinically?

Involves apex of the lung. Due to pre-existing hypersensitivity, there is little enlargement of the hilar lymph nodes
Tissue necrosis with cavitation is evident

10

What type of inflammation do you see in TB?

Granulomatous

11

Describe progressive pulmonary TB

Extension of the lung lesion, cavitation with central caseation that is not walled off by fibrous tissue
This erodes into bronchi and blood vessels, becoming 'open TB'
The disease spreads through the blood and lymph nodes

12

Describe Miliary TB

After dissemination through the lymph nodes, bacilli in venous blood get back to the lungs, and cause numerous small lesions throughout the lung

13

Where can you get TB developing?

-lungs
-CNS
-Peritoneal
-Spine

14

Which Mycobacterium species is involved in HIV disease?

Mycobacterium avium-intracelluare
Causes disseminated "MAC" infection

Decks in Pathology-IMED4111 Class (88):