Pulmonary Tuberculosis (TB)

Question 1

What is tuberculosis?

Answer 1

Infectious disease caused by mycobacterium tuberculosis bacteria

Question 2

What staining technique is used for TB and why?

Answer 2

Zeihl-Neelsen stain as it is an acid-fast bacilli

Question 3

TB transmission + disease course

Answer 3

Inhaling saliva droplets from infected people

Spreads trough lymphatics and blood

Granulomas containing the bacteria form around the body

Question 4

Risk factors for TB

Answer 4

Known contact with active TB

Immigrants from areas of high TB prevalence

People with relatives or close contacts from countries with a high rate of TB

Immunosuppression due to conditions like HIV or immunosuppressant medications

Homeless people, drug users or alcoholics

Question 5

What does the BCG vaccine involve?

Answer 5

Intradermal infection of live attenuated (weakened) TB

Offers protection against severe and complicated TB but is less effective at protecting against pulmonary TB

Question 6

Who is offered the BCG vaccine?

Answer 6

Patients that are at higher risk of contact with TB:

Neonates born in areas of the UK with high rates of TB

Neonates with relatives from countries with a high rate of TB

Neonates with a family history of TB

Unvaccinated older children and young adults (<35) who have close contact with TB

Unvaccinated children or young adults that recently arrived from a country with a high rate of TB

Healthcare workers

Question 7

Signs and symptoms of TB

Answer 7

Chronic, gradually worsening symptoms

Lethargy

Fever or night sweats

Weight loss

Cough with or without haemoptysis

Lymphadenopathy

Erythema nodosum

Spinal pain in spinal TB (also known as Pott’s disease of the spine)

Question 8

Investigations in TB

Answer 8

Mantoux test

IGRAs

CXR

Question 9

Outline the Mantoux test

Answer 9

Looks for previous immune resposne to TB

Inject tuberculin into intradermal space

After 72hrs measure induration of skin at site of injection

5mm or more is a positive result

Question 10

Outline the IGRA test

Answer 10

Take blood sample and mix it with TB antigens

If person has been infected, WBCs will release interferon-gamma

Release of interferon gamma = positive result

Question 11

What will CXR show in TB?

Answer 11

Primary TB may show patchy consolidation, pleural effusions and hilar lymphadenopathy

Reactivated TB may show patchy or nodular consolidation with cavitation (gas filled spaces in the lungs) typically in the upper zones

Disseminated Miliary TB give a picture of “millet seeds” uniformly distributed throughout the lung fields

Question 12

When is the IGRA test used?

Answer 12

Patients that do not have features of active TB but do have a positive Mantoux test to confirm a diagnosis of latent TB

Question 13

Management of latent TB

Answer 13

Otherwise healthy patients do not necessarily need treatment for latent TB

Patients at risk of reactivation of latent TB can be treated with either:
Isoniazid and rifampicin for 3 months
Isoniazid for 6 months

Question 14

Management of acute pulmonary TB

Answer 14

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

Question 15

Cautions when prescribing isoniazid

Answer 15

Causes peripheral neuropathy

Pyridoxine (vitamin B6) usually co-prescribed

Question 16

Other management considerations in tuberculosis

Answer 16

Test for other infectious diseases (HIV, hepatitis B and hepatitis C)

Test contacts for TB

Notify Public Health of all suspected cases

Patients with active TB should be isolated to prevent spread until they are established on treatment (usually 2 weeks)

Management and followup should be guided by a specialist MDT

Individualised drug regimes are required for multi-drug‑resistant TB

Question 17

Side effects of TB medication

Answer 17

Rifampicin - red/orange secretions (“red-and-orange-pissin”)

Isoniazid - peripheral neuropathy (“Im-so-numb-azid”)

Pyrazinamide - gout

Ethambutol - colour blindness, reduced visual acuity (“eye-thambutol”)

R, I, P cause hepatotoxicity