Tuberculosis (TB)

Question 1

1) What bacteria causes TB?
2) What type of bacteria is this?
3) What staining technique does the bacteria require?
4) What does a positive result look like?

Answer 1

1) Mycobacterium tuberculosis
2) Acid fast bacilli
3) Ziehl-Neelsen stain
4) Appear red on a blue background

Question 2

1) What is active TB?
2) What can cause active TB (2)?
3) How does TB transmit?
4) What is latent TB?
5) Name 2 risk factors for the reactivation of latent TB

Answer 2

1) When TB isn’t contained by the immune system
2) Primary infection or reactivation of a previously latent disease
3) Aerosol droplets
4) There’s TB infection without the disease due to immune system containment. Skin/blood testing would show evidence of infection but the patient is asymptomatic and non-infectious
5) HIV, organ transplantation, immunosuppression, illicit drug use, low socioeconomic status

Question 3

Clinical features of TB (1)
1) Name a systemic feature of TB
2) Name a pulmonary feature of TB
3) Why is the lungs the commonest site for TB infection?
4) Name a feature of tuberculous lymphadenitis (TB infection in the lymph nodes)

Answer 3

1) Fever, anorexia, weight loss, malaise, night sweats, erythema nodosum
2) Cough (dry then productive), pleurisy
3) It has a good oxygen supply
4) Painless enlargement of cervical or supraclavicular lymph nodes - ‘cold abscess’ as no inflammation or redness

Question 4

Clinical features of TB (2)
1) Name a feature of gastrointestinal TB
2) Name a feature of spinal TB
3) What is miliary TB?
3) Name 2 other areas/systems of the body that TB can affect

Answer 4

1) Ileocecal disease, colicky abdominal pain, vomiting, bowel obstruction
2) Local pain and bony tenderness
3) Severe TB disease
4) CNS, genitourinary system, cardiac, cutaneous TB

Question 5

What kind of vaccine is the BCG vaccine?

Answer 5

Intradermal infection of live attenuated TB

Question 6

What are two tests for an immune response to TB caused by previous, latent or active TB?

Answer 6

Mantoux test
Interferon gamma release assay

Question 7

What are the 2 tests/investigations that may help with the diagnosis of active TB?

Answer 7

Chest x-ray
Sputum cultures

Question 8

1) When is latent TB managed?
2) What is the management?

Answer 8

1) When patient is at risk of reactivated disease
2) Isoniazid and rifampicin for 3 months or isoniazid for 6 months

Question 9

What is the management of active TB?

Answer 9

R – Rifampicin for 6 months
I – Isoniazid for 6 months
P – Pyrazinamide for 2 months
E – Ethambutol for 2 months

Question 10

What drug is given alongside isoniazid?

Answer 10

Pyridoxine - prophylactic for peripheral neuropathy

Question 11

1) Name a side effect of rifampicin
2) Name a side effect of isoniazid
3) Name a side effect of pyrazinamide
4) Name a side effect of ethambutol
5) Name a side effect of all of these drugs
6) Which of these drugs is a potent CYP450 inducer?
7) What condition can the side effect of pyrazinamide cause?

Answer 11

1) Red/orange discolouration of secretions like urine and tears
2) Peripheral neuropathy
3) Hyperuricemia
4) Colour blindness and reduced visual acuity
5) Hepatotoxicity
6) Rifampicin
7) Gout

Question 12

How does TB typically appear on CXR?

Answer 12

Upper zone fibrosis

Question 13

Name 2 causes of a false negative mantoux test

Answer 13

• Immunosuppression (steroid therapy, AIDS, miliary TB)
• Sarcoidosis
• Lymphoma
• Anaemia/hypoalbuminaemia
• Extremes of age
• Fever