Tuberculosis

Question 1

What is meant by the ‘acid fast’ property of mycobacterium tuberculosis?

Answer 1

Its waxy coating is resistant to the acids used in the staining procedure

Question 2

What stain is used to identify TB?

Answer 2

Zeihl-Neelsen stain

Question 3

What type of granuloma is formed in TB?

Answer 3

Caseous

Question 4

What happens in primary TB

Answer 4

1. Exposure to M. tuberculosis
2. Small lung lesion known as ‘Ghon focus’ develops in the lungs
3. Ghon focus + hilar lymph nodes is known as a Ghon complex

Question 5

What is active TB?

Answer 5

Active infection in various areas within the body

In the majority of cases the immune system is able to kill and clear the infection

Question 6

What is latent TB

Answer 6

Immune system encapsulates sites of infection and stop the progression of the disease

Question 7

What is secondary TB?

Answer 7

When latent TB reactivates

Question 8

What happens if the immune system is unable to control the TB?

Answer 8

Causes a disseminated, severe disease

Referred to as miliary TB

Question 9

List 4 Extra-pulmonary TB infections

Answer 9

• CNS (tuberculous meningitis - most serious complication)
• vertebral bodies (Pott’s disease)
• cervical lymph nodes (scrofuloderma)
• renal
• GI tract

Question 10

What is a “cold abscess”?

Answer 10

A firm painless abscess caused by TB, usually in the neck

NO inflammation, redness or pain as expected

Question 11

List 4 risk factors for TB

Answer 11

1. Contact with active TB
2. Immigrants from areas of high TB
3. Immunosuppression ie. HIV
4. Homeless people or IVDU

Question 12

What type of vaccine is the BCG?

Answer 12

live attenuated

Question 13

What 2 things must be checked/assessed prior to the BCG

Answer 13

1. Mantoux test
2. Immunosuppression and HIV

Question 14

List 2 groups of people which the BGC is routinely offered too

Answer 14

1. Neonates who are born in areas in UK with high rates of TB
2. Healthcare workers

Question 15

Presentation of TB?

Answer 15

1. Lethargy
2. Fever or night sweats
3. Weight loss
4. Cough +/- haemoptysis
5. Lymphadenopathy
6. Erythema nodosum

Question 16

What is Pott’s disease?

Answer 16

Form of osteoarticular TB which affects the spine, also known as Tuberculous spondylitis?

Question 17

How does Pott’s disease present?

Answer 17

Typical TB features + Spinal pain

Question 18

Describe the typical disease pattern of Pott’s disease

Answer 18

• Starts in subchondral bone
• Follows longitudinal ligaments
• Mainly lower thoracic and upper lumbar spine
• Insidious onset over months → may progress to paralysis

Question 19

List 2 tests to check for Latent TB

Answer 19

1. Mantoux test (screening)
2. Interferon‑gamma release assay

IGRA is used if there are NO features of active TB but a positive Mantoux test to confirm a diagnosis of latent TB

Question 20

Explain the Mantoux test

Answer 20

1. Tuberculin (TB protein) injected into forearm
2. Injecting creates a bleb under the skin
3. After 72 hours the induration of the skin at the site of the injection is measured
4. Induration of ≥ 5mm is positive

Question 21

Explain the Interferon-Gamma Release Assays (IGRAs)

Answer 21

Sample of blood mixed with antigens from the TB bacteria

If patient has had previous contact with TB, interferon-gamma is released from WBC

Question 22

Investigations if active TB is suspected

Highlight gold standard

Answer 22

1. Chest xray
2. Sputum smear (3 specimens needed)
3. Sputum culture (GOLD standard)
4. NAAT (diagnosis within 24-48 hours)

Question 23

When is NAAT used over sputum cultures?

Answer 23

1. If having the information would affect treatment OR
2. They are at higher risk of developing complications (ie. in HIV)

Question 24

List 3 ways to collect cultures for suspected TB

Answer 24

1. Sputum
2. Mycobacterium blood cultures
3. Lymph node aspiration or biopsy

Question 25

List 3 chest X-ray findings of primary TB

Answer 25

1. Patchy consolidation 2. Pleural effusions 3. Hilar lymphadenopathy

Question 26

Typical chest X-ray finding of reactivated TB

Answer 26

Upper lobe cavitation

Question 27

What typical chest x-ray finding is seen in Miliary TB?

Answer 27

“Millet seeds” uniformly distributed throughout the lung fields

Question 28

Management of Latent TB?

Answer 28

1. 3 months Isoniazid (with pyridoxine) and rifampicin OR 2. 6 months of isoniazid (with pyridoxine)

Question 29

Management of Acute Pulmonary TB (RIPE)

Answer 29

* **R**ifampicin for 6 months * **I**soniazid for 6 months * **P**yrazinamide for 2 months * **E**thambutol for 2 months

Question 30

A patient is started on RIPE, what must be co-prescribed and why?

Answer 30

**Pyridoxine** Isoniazid causes peripheral neuropathy, pyridoxine (B6) should be co-prescribed prophylactically

Question 31

Is TB a notifiable disease?

Answer 31

YES - must inform PHE

Question 32

If a patient is identified to have active TB, what steps must be taken to prevent airborne spread?

Answer 32

Should be isolated until they are established on treatment (usually 2 weeks) In hospital negative pressure rooms are used to prevent airborne spread

Question 33

Treatment of meningeal TB?

Answer 33

Treated for at least 12 months with the addition of steroids

Question 34

What is Multi drug resistant TB?

Answer 34

TB resistant to isoniazid and rifampicin

Question 35

S/E of Rifampicin

Answer 35

1. Red/orange urine and tears 2. Potent inducer of CYP P450 enzymes (important for medications such as the COCP)

Question 36

S/E of Isoniazid

Answer 36

Peripheral neuropathy Pyridoxine (B6) usually co-prescribed prophylactically

Question 37

S/E of Pyrazinamide

Answer 37

Hyperuricaemia resulting in gout

Question 38

S/E of Ethambutol

Answer 38

Colour blindness and reduced visual acuity

Question 39

Which TB drugs are associated with hepatotoxicity?

Answer 39

Rifampicin, isoniazid and pyrazinamide