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What causes TB?

Mycobacterium tuberculosis


Describe mycobacterium tuberculosis

Are aerobic, alcohol and acid fast bacilliIs transmitted by aerosolised droplets


What happens in the body when mycobacterium tuberculosis is detected?

Alveolar macrophages digest the bacilli but cannot kill them due to an inability of lysosome to bind to the phagosomes. The bacteria is then released into teh cytoplasm where it can multiply. This initiates the development of cell mediated immunity, by way of IL-12 which causes the release of IFN-γ and TNF-α. These stimulate the production of activated macrophages which have the enhanced ability to kill TB. This takes up to 6 weeks.


How are tubercles formed?

Ingestion of the bacteria by macrophages causes a granulomatous reaction. It produces a spherical granuloma with central caseation. Has a necrotic cheese-like core surrounded by epithelioid cells, langerhans giant cells and lymphocytes.


What is the primary complex?

The primary focus of the infection plus the draining lymph nodes.


What is miliary spread?

When the infection spreads from the lungs to other parts of the body. It can resolve itself or develop into further localised infections.


What is the post primary infection?

Infection that spreads beyond with first few weeks


What happens when TB is reactivated?

Causes lung symptoms when the immune systems is weakened or compromised.


What is primary TB?

The primary complex does not heal and it continues to progress. Has few symptoms, but one lymph node may become enlarged in young people.


What is latent infection?

The patient is infected, but the bacteria are not causing symptoms as it is lying dormant.