20 Tuberculosis

Question 1

What bacterium caused TB?

Answer 1

Mycobacterium tuberculosis

Question 2

How many people develop TB daily?

Answer 2

28000

Question 3

How many people die by tuberculosis daily?

Answer 3

3000-4000

Question 4

What are the two phases of TB infection?

Answer 4

Primary and secondary

Question 5

What happens during the primary phase?

Answer 5

the infection process

Question 6

How is Mycobacterium tuberculosis acquired? (Transmission type)

Answer 6

Aerosols

Question 7

Where do the bacteria grow?

Answer 7

Bacteria reach the alveoli in lungs and start to grow

Question 8

What does mycobacterium tuberculosis growth in the alveoli stimulate?

Answer 8

The hosts macrophages

Question 9

What do the macrophages do?

Answer 9

Form into aggregates (tubercles) and engulf mycobacteria

Question 10

What happens to some mycobacteria after phagocytosis?

Answer 10

Survive within the macrophage - they do not succumb to the normal lysosomal destruction process

Question 11

What is the mycobacterial cell wall rich in?

Answer 11

Mycolic acid - a glycolipid

Question 12

Is mycobacterium tuberculosis Gram positive or negative?

Answer 12

It is neither

Question 13

Are mycolic acids hydrophilic or hydrophobic?

Answer 13

Hydrophobic

Question 14

What do these mycobacterial cell walls prevent and what does it limit the entry of?

Answer 14

It prevents phagocytosis from occurring

And limits the entry of antimicrobial compounds

Question 15

Primary tuberculosis (What happens to a host?)

Answer 15

Primary infection remains undetected in the host. Very rarely will acute pulmonary disease occur leading to destruction of lung tissue and death. The acute form of TB only occurs in unhealthy or already sick individuals

Question 16

What happens following infection to primary tuberculosis?

Answer 16

Following infection most people become hypersensitised to the bacterium due to cell-mediated immune response. In most people this gives life long (natural immunity) against secondary TB

Question 17

How can a person develop secondary TB (2 routes)?

Answer 17

Can get a fresh infection from another source or activation of dormant bacteria in lung macrophage

Question 18

What does secondary tuberculosis lead to?

Answer 18

Death through chronic destruction of lung tissue

Question 19

What sort of factors is secondary TB linked to?

Answer 19

Aging
Malnutrition
Poor living conditions/poverty

Question 20

Patients with secondary TB are highly what?

Answer 20

Contagious via aerosols

Question 21

Heaf test

Answer 21

Spring loaded instrument with 6 needles in a circular pattern used is Scotland on children around 11-12. Positive reactions are screened for TB with xrays and negative reaction gets a BCG vaccine (BCG reserved for those considered in high risk groups since 2005)

Question 22

What is the treatment for TB?

Answer 22

Treated my antimicrobials

Main drug is Isonazid, used in combination with zifampicin and ethambutol or pyrazinamide

Question 23

What is Isonazid and what is it activated by?

Answer 23

A prodrug activated by bacterial catalase which inhibits fatty acid synthase

Question 24

What enzyme does ethambutol inhibit?

Answer 24

Inhibits Arabinosyl transferase which disrupts arabinogalactan synthesis

Question 25

What does the Rifampicin target?

Answer 25

RNA polymerase

Question 26

What is pyrazinamide and what does it do?

Answer 26

A prodrug which the enzyme pyrazinamidase converts to pyrazionic acid (active form)

Highly specific and only used in the treatment of mycobacterium tuberculosis

Question 27

What is the generation time of mycobacterium tuberculosis? What does this mean for treatment

Answer 27

15-20 hours

Means treatment is lengthy, potential problem of compliance with treatment.

Question 28

What does Bedaquiline do? (Sirturo)

Answer 28

Became available in 2014 for use against MDR (multi-drug-resistant) TB. It targets ATP synthase in cytoplasmic membrane. It is reserved for extreme cases