Handout #5 - TB Pathophysiology - Lists

Question 1

Likelihood of TB transmission depends on…

Answer 1

Pathogenicity of the strain/virulence; the way the droplets were produced (coughing vs sneezing); frequency of the action; and the number, size and location of infected lesions.

Question 2

After bacteria are phagocytosed by macrophages, the bacteria start replicating and the macrophages respond by…

Answer 2

Activation of macrophages, release of cytokines, additional macrophages attracted, and T-cells activated.

Question 3

Steps of TB granuloma formation…

Answer 3

1. Bacteria are phagocytosed by pulmonary macrophages. 2. Bacteria inhibits the fusion of the phagosome with the lysosome and increases lysosomal pH. 3. Bacterium grows exponentially until arrested by the immune system (usually via granuloma formation). 4. Macrophages differentiate into several forms. 5. Most of the macrophages become excluded by a build up of fibres which create a barrier around the centre. 6. Inside, a caseous necrosis forms.

Question 4

Risk factors for TB…

Answer 4

Time, presence of latent infection, age, sex (adolescent and middle aged women, men over 60), genetics, stress, nutrition, occupation, smoking, diabetes, HIV.