TB

Question 1

Is TB caused by virus or bacteria if so what is the most common causative organism

Answer 1

Bacteria -

Myobacterium TB

Question 2

List causative organisms

Answer 2

• mycobacterium TB
• M. Bovis (anima to human or via unpasturised milk)
• m.african (mainly in west Africa)

Question 3

Can latent or inactive TB spread from one person to another

Answer 3

No

Question 4

Describe the pathogenesis

Answer 4

1. Infected aerosol droplets which contain myobacterium TB enters the air via infected person (can remain in air for hours)
2. Once inhaled it enters the alveoli where macrophages engulf it.
3. Macrophages recruit T cells and other inflam cells forming a granuloma around the bacteria.

This is latent TB, asymptomatic and does not spread

4. however in immunosuppressed individuals the bacteria can reactivate into active TB, where it escapes granuloma and replicate.

In active TB, bacteria can enter blood stream via lymphatic system to other organs - dismounted TB (millary TB), affecting kidneys, brain, bones and liver

5. Cavitary lesions occur - from tissue destruction in the alveoli. This can increase risk of transmission (visible on chest x ray)

Question 5

TB risk factors

Answer 5

remember risk factors do not need to be present

• < 5 years
• born in a area with high prevalence
• take immunosuppressive agents - corticosteroids
• co-morbidities (CKD) or Kidney transplant, diabeties
• hx of TB

Question 6

Clinical presentations of active TB

Answer 6

• low grade fever
• night sweats
• sputum production
• weight loss
• anorexia
• heamoptysis

Question 7

Locations of extra pulmonary TB

Answer 7

• lymph nodes (most common)
• CNS
• joints/bones
• abdominal area
• plurea

Question 8

What is Millary TB?

Answer 8

When bacteria entered blood stream and affects organs

Question 9

Symptoms of pulmonary TB

Answer 9

• breathlessness
• heamoptysis
• persistent productive cough

Question 10

Symptoms of joint and bone pain indicates what type of TB (extrapulmonary)

Answer 10

Skeletal TB

Question 11

Symptoms of abdominal pain?

Answer 11

GI TB

Question 12

Urinary symptoms

Answer 12

Genitoururinary TB

Question 13

Sterile pyuria (WBC in urine)

Answer 13

Renal TB

Question 14

Symptoms of headache, vomiting, confusuion and cranial nerve pain

Answer 14

Meningitis TB

Question 15

Symptoms of breathlessness, chest pain and ankle swelling?

Answer 15

Pericarditis TB

Question 16

Ocular symptoms?

Answer 16

Ocular TB

Question 17

Tests/investigations for Latent TB?
+
Pulmonary
+
Extra pulmonary

Answer 17

• Mantoux test (skin test)
• IGRA
• AFB - for sputum

• Chest x ray
• sputum microbiology

• cheat x ray
• CT
• ultrasound
• respiratory sample

Question 18

Differential Diagnosis of TB

Answer 18

• COPD
• ASHMA
• lung cancer
• COVID
• fever
• cough

Question 19

Who should the doctor inform about active TB?

Answer 19

Local public health - to help track and trace

Question 20

Should the doctor inform public health about latent TB

Answer 20

No

Question 21

What is the TB vaccine

Answer 21

BCG - contains a live strain of mycobacterium Bovis

Question 22

Who should the BCG vaccine be offered to?

Answer 22

• infants at high exposure
• children living with those with respiratory disorders
• <35 at occupational risk

Question 23

What treatment is used in the initial phase of active TB?

Answer 23

rivampicine + isoniazide (with pyridoxine) + Ethanbutol + pyrazinamide

For 2 months

Question 24

What treatment is used in continuous phase

Answer 24

rivampicine + isoniazide (with pyridoxine)

For another 4 months (6 month of treatment in total)

Question 25

What drugs are used for treatment in Latent TB (2 options

Answer 25

rifampicin + isoniazide (with pyridoxine) - 3m isoniazide (with pyridoxine) - 6 m

Question 26

Which agent is a pro drug

Answer 26

Pyrazinamide

Question 27

Rifampicin moa?

Answer 27

Inhibits RNA synthesis and binds to b subunit

Question 28

Isonizide MOA

Answer 28

inhibits synthesis of mycolic acid

Question 29

Ethambutol MOA

Answer 29

Disrupts mycobacterium cell wall

Question 30

Pyrazinamide MOA

Answer 30

Accumulates the acidic environments of the the bacteria and affects its energy

Question 31

Which drug affects the eyes and thus eye test is required?

Answer 31

Ethambutol (by snellen chart)

Question 32

Which drug turn urine red

Answer 32

Rifampicin

Question 33

Which drug increases uric acid?

Answer 33

Ethambutol

Question 34

Which drug should be avoided in patients with gout

Answer 34

Pyrazinamide

Question 35

Why is isoiazide taken with Pyridoxine

Answer 35

Isoniazide can cause neuropathy so it is taken with this B6 vitamin

Question 36

What is DOT and who is it offered to

Answer 36

Directly observed therapy Offered to: • hx or current poor adherence • hx of homelessness • hx drug miss-use • previous treatment to TB • those in denial of TB • cognitive disorder • those who ask • have been to prison within last 5 years

Question 37

Is TB curable?

Answer 37

Yes

Question 38

Why is TB common in those with HIV

Answer 38

In HIV CD4 cells decrease (weakening of immune system) CD4 cells are key in TB, they activate macrophages to kill bacteria and form granulomas

Question 39

Is M. TB Aerobic or anaerobic

Answer 39

Aerobic (needs oxygen) Remember lungs are oxygen rich

Question 40

Is cavitation more prominent in latent or active tb

Answer 40

Active tb

Question 41

Does TB bacci stain red/pink or blue

Answer 41

Red/pink

Question 42

When reactivation occurs after latent TB, where in the lungs does it multiple

Answer 42

Upper lungs - oxygen levels are high promoting bacterial growth

Question 43

Can cavity lesions increase risk of transmission

Answer 43

Yes

Question 44

When treating active TB iv CNS The initial phase is 2 months How long is continuous phase?

Answer 44

10 months

Question 45

In CNS active TB what other drug should also be given

Answer 45

An initial dose of dexomethasone or predisolone at the same time as tb treatment

Question 46

In pericardial TB what other drug should also be given

Answer 46

An initial dose of prednisone at the same time as tb treatment

Question 47

Which drug causes optic neuritis

Answer 47

Ethambutol

Question 48

What drug is used if rifampicin in CI

Answer 48

Streptomycin (amino-glycoside)

Question 49

Main ADR of streptomycin

Answer 49

Auditory nerve toxicity (hearing loss)