mycobacterium tuberculosis

Question 1

what is mycobacterium tuberculosis

Answer 1

a bacteria which colonises lung tissue and is spread by droplet infection when mucus and saliva is released into the air when an infected person coughs or sneezes

Question 2

risk factors TB

Answer 2

• poor ventilation
• close contact with an infected person
• poor health
• poor diet
• overcrowding

Question 3

who is most at risk if developing TB

Answer 3

• family and friends of an infected person
• babies and young children
• people with chronic conditions
• organ transplant patients
• injection drug users

Question 4

primary infection (latent phase)

Answer 4

1. last several months and be asymptomatic
2. inflammatory response causes macrophages to engulf and destroy bacteria and become APC
3. T cells are activated and infection spread is stopped
4. a granuloma forms around the site of infection and seals off dead bacteria and macrophages
5. however some TB avoid being destroyed due to their thick waxy coat making them difficult to digest with lysosomal enzymes
6. these bacteria then enter a state of dormancy and last many years

Question 5

active tuberculosis

Answer 5

• immune system cannot contain the bacteria fromprimary infection or if dormant bacteria is reactivated ( e.g someone with a weak immune system)
• mycobacterium multiply rapidly and overwhelm the immune system
• mycobacterium inhibit the activity of T helper cell
• initial symptoms include fever, general weakness and sever coughing caused by inflammation of the lungs
• can spread to other parts of the body and lead to organ failure and death

Question 6

how is TB bacterium adapted to evade the immune system

Answer 6

• thick waxy cell wall making them difficult to digest
• waxy cell wall also acts as a barrier to antibiotics
• they can remain dormant for years