TB

Question 1

TB

Answer 1

Mycobacterial infection

Chronic infection in many body sites

Question 2

Pathology

Answer 2

Delayed hypersensitivity (granulomas with necrosis)

Question 3

Immunity and Hypersensitivity

Answer 3

T-Cell response to organism enhances macrophage ability to kill mycobacteria
TYPE IV HYPERSENSITIVITY REACTION:
T-Cell response causes granulomatous inflammation, tissue necrosis and scarring

Question 4

Primary TB

Answer 4

1st exposure, up to 5 years after
Inhaled organism phagocytosed and carried to hilar lymph nodes
Immune activation leads to granulatomous response in nodes, killing organism
Tissue changes in Ghon focus in periphery of mid zone of lung and large hilar lymph nodes

Question 5

Secondary TB

Answer 5

Reinfection or reactivation
Initially disease remains localised in apices of lungs
Can progress to spread by airways or bloodstream
Tissue changing = fibrosing and cavitating apical lesion

Question 6

Why does it reactivate

Answer 6

1. Decreased T cell activation (age, coincident disease - HIV, immunosuppressive therapy)
2. Reinfection at high does or with more virulent organism

Question 7

Mycobacterium TB

Answer 7

Rod shaped gram positive bacilli

Question 8

Investigation

Answer 8

Ziehl-Neelsen stain

CXR

Question 9

Histology

Answer 9

Granulomata with caseous necrosis

Question 10

Treatment for active TB

Answer 10

2 months RIPE

Question 11

RIPE

Answer 11

Rifampicin = orange fluids
Isoniazid = neuropathy
Pyrazinamide = joint pain
Ethambutol = colour blindess

Question 12

latent TB

Answer 12

Symptom free
No evidence for active TB
Previous TB infection

Question 13

Treatment of latent TB

Answer 13

6 months of Isoniazid or 3 months of RI

Question 14

What therapy may reactiavate TB

Answer 14

ANTI TNF therapy