Tuberculosis

Question 1

What are the risk factors for tuberculosis?

Answer 1

Diabetes

Immunosuppressed

Alcohol

Poor social circumstances/malnourished

Immigrant/overseas travel

HIV

Question 2

What organisms cause TB?

Answer 2

Mycobacterium tuberculosis

Mycobacterium bovis

Question 3

How is mycobacterium tuberculosis spread?

Answer 3

Air-borne transmission

Question 4

How is mycobacterium bovis spread?

Answer 4

Un-pastered milk

Question 5

How is miliary tuberculosis spread?

Answer 5

Haematogenous spread of tubercle bacilli through the pulmonary venous system

Question 6

Describe the presentation of TB

Answer 6

Haemoptysis

Persistent cough with grey sputum production

Weight loss

Dyspnoea

Lethargy

Night sweats

Fever

Erythema nodosum

Question 7

What area of the lung does TB favour?

Answer 7

Upper lobes

Question 8

What investigations are used in TB diagnosis?

Answer 8

CXR

Sputum culture with Zeil Neilson stain

• 3+ on successive days

Bronchoscopy and biopsy for histology with Zeil Neilson stain

Question 9

What investigations are used in TB monitoring?

Answer 9

Visual acuity: Optic neuritis due to Ethambutol

LFT: Liver failure

U&E: Renal failure

Question 10

What CXR findings are present in TB?

Answer 10

Bilateral hilar lymphadenopathy

Upper lobe cavitation

Millet seeds in miliary TB

Question 11

What is the management of TB?

Answer 11

RIPE

Rifampicin

Isoniazid

Pyrazinamide

Ethambutol

All for 2 months, then first 2 for 4 more months

Question 12

What are the side effects of Rifampicin?

Answer 12

Orange urine

Hepatitis

It is a potent inducer of cytochrome P450 enzymes therefore reduces the effect of drugs metabolised by this system, such as COCP

Question 13

What are the side effects of Isoniazid?

Answer 13

Peripheral neuropathy

Hepatitis

Agranulocytosis

Question 14

What are the side effects of Pyrazinamide?

Answer 14

Gout

Hepatitis, most commonly

Question 15

What are the side effects of Ethambutol?

Answer 15

Optic neuritis

Question 16

What is given to prevent peripheral neuropathy caused by Isoniazid?

Answer 16

Pyridoxine

Question 17

What is multi-drug-resistant TB (MDR-TB)?

Answer 17

Resistance to rifampicin and isoniazid

Teatment is complicated and must be done under specialist centres, usually involving five or more drugs to which the bacteria is susceptible for a minimum of 9 months

Question 18

What investigation should be offered to all TB patients?

Answer 18

HIV testing

Question 19

Why are LFTs measured prior to and during TB therapy?

Answer 19

Rifampicin, Isoniazid and Pyrazinamide can call cause hepatitis

Question 20

What drug is given to prevent Ethambutol associated optic neuritis?

Answer 20

Pyridoxine

Question 21

What is the mechanism of action of Rifampicin?

Answer 21

Inhibits bacterial DNA dependent RNA polymerase preventing transcription of DNA into mRNA

Question 22

What is the mechanism of action of Isoniazid?

Answer 22

Inhibits mycolic acid synthesis

Question 23

What is the mechanism of action of Pyrazinadmide?

Answer 23

Converted by pyrazinamidase into pyrazinoic acid which in turn inhibits fatty acid synthase (FAS) I

Question 24

What is the mechanism of action of Ethambutol?

Answer 24

Inhibits the enzyme arabinosyl transferase which polymerizes arabinose into arabinan

Question 25

What causes peripheral neuropathy with Isoniazid?

Answer 25

B6 deficiency

Question 26

What type of bacteria is mycobacterium tuberculosis?

Answer 26

acid-fast bacilli Meaning they are rod shaped and resistant to the acids used in staining procedures, so require ZN stain

Question 27

What colour does mycobacterium tuberculosis turn with ZN stain?

Answer 27

Red against blue background

Question 28

What are the classifications of TB?

Answer 28

Active, where infection is active in various areas of body Latent, in which immune system encapsulates site of infection and stops disease progression Secondary, when latent TB reactivates Disseminated/Miliary, in which immune system is unable to control disease Extrapulmonary, in which TB affects other areas

Question 29

What can cause a false negative Mantoux test?

Answer 29

Immunosuppression/steroids Sarcoidosis Lymphoma Extremes of age Fever Hypoalbuminaemia Anaemia

Question 30

What investigation is used to identify latent TB?

Answer 30

Interferon gamma release assay (IGRA)

Question 31

Give features of aspergilloma

Answer 31

Fungus arising secondary to TB, lung cancer, CF Cough Haemoptysis Rounded opacity with crescent sign on xray