Tuberculosis

Question 1

Describe the Microbiology of Mycobacterium Tuberculosis

Answer 1

• Rod shaped
• Strict aerobe
• Mycolic acid cell wall
• Acid-fast (Red on Zeihl-Neeson stain)

Question 2

What three tests can be performed to confirm Tuberculosis?

Answer 2

• Mantoux test
• Heaf test
• Interferon gamma release assays (IGRA)

Question 3

How is Tuberculosis transmitted?

Answer 3

Respiratory spread (inhalation)

Question 4

How can Mycobacterium invade host defences and cause a Primary TB infection?

Answer 4

Mycobacterium is engulfed by Alveolar macrophages, however TB can evade lysosomal degradation and proliferate within the alveolar macrophages

Question 5

What is a Ghon focus?

Answer 5

A caseating granuloma in a TB infection

Question 6

What is a Ghon complex?

Answer 6

A Ghon focus which has infiltrated associating lymphoid tissue

Question 7

Where do Ghon complexes tend to occur?

Answer 7

Subpleura and lower lobes of the lungs

Question 8

What is a Ranke complex?

Answer 8

Ghon complexes which have undergone fibrosis and calcification

Question 9

Under what circumstances might a Latent TB infection reactivate to Symptomatic TB?

Answer 9

In aging / AIDS

Question 10

How might Systemic Miliary TB affect the Kidneys?

Answer 10

Sterile pyuria; WBCs in urine

Question 11

How might Systemic Miliary TB affect the Lumbar vertebae?

Answer 11

Pott disease

Question 12

How might Systemic Miliary TB affect the Meninges of the brain?

Answer 12

Meningitis

Question 13

How might Systemic Miliary TB affect the Adrenal glands?

Answer 13

Addison’s disease (Primary adrenal insufficiency)

Question 14

How might Systemic Miliary TB affect the Liver?

Answer 14

Hepatitis

Question 15

What is the treatment for TB? What is the duration for each drug?

Answer 15

2 antibiotics: Isoniazid and Rifampicin (6 months)

2 additional antibiotics:
Pyrazinamide and Ethambutol (2 months)

Question 16

What cells are found in a Granulomatous conditions of a TB infection?

Answer 16

Giant Langerhan cells

Question 17

Which regions of the lungs does TB infect? Why?

Answer 17

Upper lobes, because O2 levels are higher here

Question 18

What is Alectasis?

Answer 18

Collapse of a lung or lobe of a lung, when alveoli within the lung become deflated

Question 19

What group(s) of people are at risk of developing TB?

Answer 19

• Urban poor
• Alcoholics
• IVDU
• Homelessness
• Prison inmates

Question 20

What is Interferon Gamma alpha?

Answer 20

IFG-a is released from T-helper lymphocytes in response of Mycobacterium tuberculosis

Question 21

Of all the TB medications, which one turns urine orange / red?

Answer 21

Rifampicin

Question 22

What is Multi-drug resistant TB defined as?

Answer 22

Resistance to Isoniazid and Rifampicin

Question 23

What is Extreme Multidrug Resistance TB defined as?

Answer 23

Resistance to Isoniazid and Rifampicin

And…

Resistance to any fluoroquinoline, and one of three injectable second line drugs

Question 24

What is the mechanism of action for Isoniazid?

Answer 24

Mycolic acid synthesis inhibitor

Question 25

What is the mechanism of action for Rifampicin?

Answer 25

DNA-dependent RNA polymerase inhibitor

Question 26

What is the mechanism of action for Ethambutol?

Answer 26

Mycolic acid synthesis inhibitor

Question 27

What is the mechanism of action for Pyrazinamide?

Answer 27

• Fatty acid synthesis inhibitor
• Membrane disruption
• Trans-translation inhibitor