Tuberculosis

Question 1

What is the mortality associated with TB.

Answer 1

TB kills 2 million people/year.

Question 2

What group of people are particularly vulnerable to TB infection.

Answer 2

TB is the leading cause of death in patients with HIV.

Question 3

What are the risk factors associated with contracting TB infection if you are HIV+. (5)

Answer 3

Low CD4 count. 
High ESR. 
Many co-infections. 
Poor nutrition. 
High viraemia.

Question 4

What is the UK incidence of TB.

Answer 4

8200/year.

Question 5

What is the mortality due to TB in the UK.

Answer 5

Approximately 350 deaths/year.

Question 6

How is latent TB diagnosed. (2)

Answer 6

Mantoux test.

Interferon-gamma testing (if mantoux positive or non-reliable).

Question 7

What stain is used for TB.

Answer 7

Ziehl-Neelsen stain.

Question 8

What CXR finding suggest TB. (4)

Answer 8

Consolidation.
Cavitation.
Fibrosis.
Calcification.

Question 9

What is the histological hallmark of TB infection.

Answer 9

Caseating granulomata.

Question 10

What is PCR used for in diagnosis of TB.

Answer 10

Rapid identification of rifampicin resistance.

Question 11

How do you diagnose active TB infection. (3)

Answer 11

If CXR suggests TB, take sputum samples. (>3 with one early morning sample, before treatment if possible).
Send samples for MCandS for acid fast bacilli testing.
If spontaneously produced sputum cannot be obtained, bronchoscopy and lavage may be needed.

Question 12

What samples could be taken if active non-respiratory TB is suspected. (8)

Answer 12

Sputum. 
Pleura and pleural fluid. 
Urine. 
Pus. 
Ascites. 
Peritoneum. 
Bone marrow. 
CSF.

Question 13

In the samples taken from a patient with non-respiratory TB, how long should the samples be cultured for.

Answer 13

Incubate the samples for up to 12weeks on Lowenstein-Jenson medium.

Question 14

What investigation should be carried out in all patients with non-respiratory TB (apart from cultures).

Answer 14

CXR to look for active respiratory TB.

Question 15

How might pulmonary TB present. (12)

Answer 15

It may be silent. 
Cough. 
Sputum production. 
Malaise. 
Weight loss. 
Night sweats. 
Pleurisity. 
Pyrexia of unknown origin. 
Haemoptysis (may be massive). 
Pleural effusion (exudate). 
Spontaneous pneumothorax. 
Superimposed pulmonary infection.

Question 16

What may be present in the cavities of pulmonary TB.

Answer 16

Aspergilloma/mycetoma may form in the cavities formed by TB.

Question 17

What are the features of miliary TB. (4)

Answer 17

Occurs following haematogenous dissemination.
Signs may be non-specific or overwhelming.
Look for retinal TB.
Biopsy of ling, liver, lymph nodes or marrow may yield AFB or granulomata.

Question 18

What are the features of GU TB. (5)

Answer 18

Dysuria. 
Frequency. 
Loin/back pain. 
Haematuria. 
Sterile pyuria.

Question 19

Where might renal TB spread to. (4)

Answer 19

Bladder.
Seminal vesicles.
Epididymis.
Fallopian tubes.

Question 20

What should you look for in bone TB. (2)

Answer 20

Vertebral collapse.

Pott’s vertebra.

Question 21

What should you look for in skin TB.

Answer 21

Look for jelly-like nodules.

Question 22

What are the features of peritoneal TB. (3)

Answer 22

Abdominal pain.
GI upset.
Look for AFB in ascites.

Question 23

What is acute TB pericarditis.

Answer 23

A primary exudative allergic lesion.

Question 24

What is the mortality rate for TB meningitis.

Answer 24

30%.

Question 25

What are the features of TB meningitis. (11)

Answer 25

Often worsening over 1-3weeks:
Fever. 
Headache. 
Vomiting. 
Abdominal pain. 
Drowsiness. 
Meningism. 
Delirium.
Seizures (may be the only first sign). 
Tremor. 
Papilloedema. 
Cranial nerve palsies.

Question 26

What are the risk factors for TB infection. (6)

Answer 26

Poverty. 
Alcohol. 
Smoking. 
Contact with TB. 
Immunosuppression (HIV, DM, malignancy, extremes of age). 
Renal disease.

Question 27

What is the causative organism in TB.

Answer 27

Mycobacterium tuberculosis.

Question 28

What is the route of transmission for TB.

Answer 28

Inhalation.

Question 29

What is a Ghon focus.

Answer 29

A pale yellow, caseous nodule, usually a few mm to 1-2cm in diameter.
It is the classical tuberculous granuloma (the primary lesion).
It is usually located in the periphery of the lung.

Question 30

What are the symptoms of miliary TB. (12)

Answer 30

2-3weeks of fever, weight loss, night sweats, anorexia and a dry cough.
Hepatosplenomegaly may develop.
The presence of a headache may indicate coexistent TB meningitis.
Widespread crackles in advanced disease.
Choroidal tubercles may be present on fundoscopy.
CXR may show ‘millet seed’ lesions.
Anaemia and leucopenia reflect bone marrow involvement.

Question 31

What is the differential for consolidation/collapse on a CXR. (3)

Answer 31

Pneumonia.
Bronchial carcinoma.
Pulmonary infarct.

Question 32

What is the differential for cavitation on a CXR. (5)

Answer 32

Pneumonia/lung abscess. 
Lung cancer. 
Pulmonary infarct. 
Granulomatosis with polyangiitis (Wegener's granulomatosis). 
Progressive massive fibrosis.

Question 33

What is the differential for ‘miliary’ diffuse shadowing on a CXR. (4)

Answer 33

Sarcoidosis.
Malignancy.
Pneumoconiosis.
Infection (histoplasmosis).

Question 34

What is the differential for pleural effusion/empyema on CXR. (4)

Answer 34

Bacterial pneumonia.
Pulmonary infarction.
Carcinoma.
Connective tissue disorder.

Question 35

Who most commonly presents with extra-pulmonary TB.

Answer 35

HIV positive patients.