TB

Question 1

Which bacteria is the commonest cause of TB?

Answer 1

Mycobacterium tuberculosis

Question 2

What is the primary test for TB? Other tests? Appearance on imaging?

Answer 2

PCR
ZN stain, histology, bronchoscopy
CXR (UPPER LOBE CONSOLIDATION)

Question 3

TB involves non-caseating necrosis. True/False?

Answer 3

False

It is caseating

Question 4

What is interferon gamma testing re TB?

Answer 4

Diagnoses latent TB

Measures how much IFG is released from T cells in response to stimuli (MTB)

Question 5

Which 4 drugs are used for TB?

Answer 5

Rifampicin
Isoniazide
Pyrazinamide
Ethambutol

Question 6

Start of with 4 months on RI, then 2 months on PE. True/False?

Answer 6

False

2 months on RIPE, then 4 months on RI

Question 7

List some adverse reactions of Rifampicin

Answer 7

Hepatitis
Orange-red urine
Flu syndrome

Question 8

List some adverse reactions of Isoniazide

Answer 8

Hepatitis

Peripheral neuropathy

Question 9

List some adverse reactions of Pyrazinamide

Answer 9

Hepatitis

Hyperuricaemia

Question 10

List some adverse reactions of Ethambutol

Answer 10

Optic neurotis - colour blindness —> blindness

Arthralgia

Question 11

What proportion of the world population is affected by TB?

Answer 11

1/3

Question 12

Which components make up the necrosis in TB?

Answer 12

Epitheloid cells and Langhan’s giant cells, causing formation of Ghon focus

Question 13

When might the Mantoux/tuberculin skin test for TB be false negative? When is it used?

Answer 13

If patient has had a BCG vaccination

For latent diagnosis - shows a T4 hypersensitivity reaction

Question 14

Where is TB commonly found? What is it’s prevalence?

Answer 14

Africa, Asia
10% disease (5% primary, 5% reactivation)
90% latent infection

Question 15

Describe how TB infects the host…

Answer 15

Mycobacteria migrate to lungs forming granuloma in macrophages (bacteria cannot be digested) - if bacteria escape granuloma of lymph nodes this causes active disease

Question 16

List some signs of TB…

Answer 16

Weight loss
Night sweats
Cough/Haemoptysis/SOB/Upper zone crackles
GI pain
Back pain
Renal failure

Question 17

What is the risk associated with treating latent TB?

Answer 17

Reactivation of the disease

Question 18

Methods of preventing TB…

Answer 18

Contact tracing
Screening of high risk esp. HIV +
Isolation of infectious cases
BCG immunisation