Tuberculosis

Question 1

What is tuberculosis?

Answer 1

A chronic granulomatous disease caused by Mycobacterium tuberculosis

Question 2

How is it transmitted?

Answer 2

Inhalation of droplets infected with Mycobacterium tuberculosis.

Question 3

Epidemiology

Answer 3

1/3 of the global population has latent TB infection

More than 95% of deaths due to TB occur in low and middle-income countries, where it is a leading cause of more mortality

1/5 of all HIV deaths are due to TB.

The incidence of TB in the UK is high compared to other Western countries (13.9/100000 in 2012)

Question 4

Risk factors

Answer 4

Ethnic minority groups (most commonly those from sub-Saharan Africa and South Asia).

The homeless

Drug and alcohol abuse

Close contact with infected patient

Immunosuppression: HIV, chronic organ failure, Diabetes Mellitus, chronic malnutrition.

Young or old age: due to immature immune systems in the very young.

Question 5

General presentation

Answer 5

Subacute to chronic in onset

Symptoms depend on the main site of infection, but are usually accompanied by;
night sweats
fever
weight loss
other systemic symptoms

Question 6

Pulmonary presentation

Answer 6

Most common

Chronic cough productive of purulent sputum +/- haemoptysis.

Can get bronchiectasis, pneumonia and pleural effusions.

Question 7

Pericardial presentations

Answer 7

Pericardial effusions

Constrictive pericarditis (usually see calcification of the pericardium on imaging)

Question 8

Investigations

Answer 8

Can’t be stained with traditional gram stains and requires specialist stains like the Ziehl-Neelsen stain.

Question 9

Management

Answer 9

Isoniazid, rifampicin, ethambutol, and pyrazinamide for 2 months

Isoniazid and rifampicin for a further 4 months.

Question 10

Side effects of Isoniazid

Answer 10

Peripheral neuropathy (pyridoxine is given to prevent this)

Liver toxicity

Question 11

Side effects of Rifampicin

Answer 11

Liver toxicity

Hepatic enzyme (p450) inducer

Turns bodily fluids red/orange colour.

Question 12

Side effects of Ethambutol

Answer 12

Visual disturbance (colour blindness, loss of acuity etc.)

Avoid in chronic kidney disease.

Question 13

CXR

Answer 13

Consolidation with/out cavitation

Pleural effusion

Thickening/worsening if mediasteinum by hilar/paratracheal adenopathy

Question 14

Risk factors

Answer 14

Being of certain ethnic minority backgrounds (especially those from sub-Saharan Africa and South Asia) – the risk is highest if the patient has returned from a high-prevalence country in the last 5 years

Homelessness

Drug and alcohol abuse

Close contact with infected patient

Immunosuppression

Young or old age

Question 15

Most common CXR finding in TB

Answer 15

Patchy pattern of opacification, sometimes described as “fibronodular”.

Question 16

What type of sample is helpful in TB diagnosis?

Answer 16

Early morning sputum samples

Question 17

What does Pyrazinamide cause?

Answer 17

Acute hepatotoxicity, arthralgia aka joint pain

Yellow eyes and skin

Question 18

What vitamin is given to prevent peripheral neuropathy?

Answer 18

Pyridoxine - Vitamin B6

Question 19

What should all patients who are being investigated for TB should be tested for?

Answer 19

HIV infection

Question 20

Who should BCG vaccination be given to?

Answer 20

Tuberculin skin test negative (mantoux negative) contacts of patients with confirmed pulmonary and laryngeal TB, who have not been previously vaccinated and are under the age of 35 or are over the age of 35 and work in healthcare.

Question 21

What is a positive mantoux test?

Answer 21

Apositive result would have been 5mm or more