TB

Question 1

How is TB spread?

Answer 1

• Airborne

Question 2

Where does mycobacterium invade and replicate?

Answer 2

• Aveolar macrophages
• Mycobacterium TB has thick, waxy mycolic acid capsule, protects it from toxic substances

Question 3

Why is mycobacterium acid-fast?

Answer 3

• High mycolic acid in cell wall

Question 4

What are granulomas?

Answer 4

• aggregates of epitheliod macrophages
• Multi-nucleated macrophages - Langhann giant cells
• Mycobacterium in granulomas can become dormant - latent TB
• Centre has caseous necrosis

Question 5

How is a granuloma organised?

Answer 5

• Macrophages centrally, surrounded by a rim of lymphocytes

Question 6

How can TB be killed?

Answer 6

• CD4 cells activate macrophages to kill bacilli
• CD8 release chemicals to break down affected cells

Question 7

What stain is used for TB?

Answer 7

• Ziehl-Neelsen stain

Question 8

What is primary TB?

Answer 8

• Usually in childhood
• Granuloma in mid zone of lung: GHON FOCUS

Question 9

What is a primary complex?

Answer 9

• Ghon focus + hilar nodes

Question 10

What is miliary TB?

Answer 10

• Dissemination of primary TB

Question 11

What is secondary TB?

Answer 11

• Reactivation of latent TB (initial content may be years before)

Question 12

What are key areas where latent TB occurs?

Answer 12

• Posterior subapical
• Upper part of lower lobes

Question 13

What is a complication of secondary TB?

Answer 13

• Fibrotic cavities form

Question 14

What factors are involved in reactivation of latent TB?

Answer 14

• HIV
• Immunosuppression
• Diabetes
• Aging
• Chronic illness
• Malnutrition
• Coal workers

Question 15

How does acute tuberculosis bronchopneumonia arise?

Answer 15

• Arises from either primary or secondary TB

Question 16

What is extra pulmonary TB? (EPTB)

Answer 16

• TB that occurs in organ systems other than the lungs
• GI tract, CNS, spinal cord, bone, lymph etc.

Question 17

What is the pathology of extrapulmonary TB?

Answer 17

• Tissue destruction, fibrosis and scarring
• Granuloma, tuberculoma
• Cold abscess, exudates

Question 18

What are classic examples of extrapulmonary TB?

Answer 18

• CNS: TB meningitis in developing nations
• Lymph: neck
• Bone: spine
• TB arthritis: spine, destruction of vertebrae

Question 19

What are non-tuberculosis mycobacteria?

Answer 19

• Mycobacterium avium-intracellulare
• Mycobacterium kansasii
• Mycobacterium marinum

Question 20

How is TB acquired?

latent or active?

Answer 20

• From person with ACTIVE TB infection

Question 21

What is the most common TB?

Answer 21

• Latent, 90%

Question 22

How often does latent TB become active TB?

Answer 22

• 5-10% of times

Question 23

What are symptoms of pulmonary TB?

Answer 23

• Drenching night sweats
• Weight loss
• Fever
• Productuve cough
• Haemoptysis

Question 24

What are the symptoms of extra-pulmonary TB?

Answer 24

TB lymphadenitis: swollen lymph nodes
TB osteomyelitis: pain at site of infection
TB meningitis: drowsy, headache, neck stiffness

Question 25

What are signs of TB?

Answer 25

• Cachexia
• Clubbing (pulmonary TB)
• Coarse crackles (pulmonary TB)
• Palpable lymph, tenderness, confusion (extra-pulmonary TB)

Question 26

How is latent TB tested?

Answer 26

• Tuberculin test (Mantoux)
• Quantiferon test

Question 27

How is active TB tested?

Answer 27

• Culture
• Ziehl-Neelsen

Question 28

How is PCR used to test for TB?

Answer 28

• TB geneXpert
• definitive diagnosis made in 2 hrs
• testd for Rifampicin resistance

Question 29

How is extra-pulmonary TB diagnosed?

Answer 29

• Biopsy from specific region

Question 30

How is latent TB managed?

Answer 30

• Rifampicin 4 months
• Isoniazid 9 months

not mandatory to take for latent

Question 31

How is active TB managed?

Answer 31

• RIPE
• multiple drugs used to reduce risk of drug resistance
• 6 months to 2 years

Question 32

What infection does TB co-exist with?

Answer 32

• HIV