TB

Question 1

What is TB?

Answer 1

An infectious disease of the respiratory tract due to the airborne spread of mycobacterium tuberculosis
It often presents in the upper lung but systemic and circulatory problems can occur and it can spread to other organs

Question 2

Where is TB common?

Answer 2

Africa, India, the indian subcontinent, China, Aisa and Indionesia

Question 3

Does TB have an environmental reservoir?

Answer 3

Not that we know of

Question 4

Where are the cases in Tayside presenting from?

Answer 4

Eastern Europe or Pakistan

Question 5

What happens after TB exposure?

Describable latent TB.

Answer 5

Tb infects the upper zone of the lungs- latent infection
Travels to the distal alviolus and phagacytosed by alveolar macrophages and dendritic cells
Transendothilial migration leads to the formation of a granuloma. The infection can grow and multiply here
The granuloma walls are very think and if contained the infection remains latent here

Question 6

What happens during active TB?

Answer 6

If the gramuloma walls break the infection will be released into the lungs

Question 7

What percentage of those with TB infection will remain well and what is the lifetime risk of tuberculosis for them?

Answer 7

90% will remain well

10% lifetime risk of infection. 5% primary TB and 5% reactivation of latent disease

Question 8

What are the clinical features of Primary pulmonary TB?

Answer 8

1) Sub acute disease, gradual onset
2) Weight loss, malaise, night swears
3) Cough, haemoptysis, breathlessness
4) Upper zone crackles and tubercles (white dots) and cavity formation

Question 9

What are the clinical features of meningeal TB?

Answer 9

Headache, drowsy, fits and TB in CSF

Question 10

What are the clinical features of gastrointestinal TB?

Answer 10

Pain, bowel obstruction, perforation and peritonitis

Question 11

What are the clinical features of spinal TB?

Answer 11

Pain, deformatity and paraplegia

Antibiotics for 12 months

Question 12

What are the clinical features of pericardial TB?

Answer 12

Tamponade

Question 13

What are the clinical features of renal TB?

Answer 13

Renal failure

Question 14

What are the clinical features of adrenal TB?

Answer 14

Hypoadrenalism

Question 15

Why should you never inject steroids into a solitary arthritic joint?

Answer 15

It may be septic arthritis caused by TB

Question 16

What form of TB is lymphadenopathy associated with?

Answer 16

Mediastinal TB

Question 17

A cold abscess can appear on the chest. What is this a sign of?

Answer 17

Dormant TB- no pain or associated inflammation

Question 18

How is TB diagnosed?

Answer 18

Culture
PCR- 90% sensitive (can give false positives for current infection and does not give antibiotic sensitivities but rapid)
Zeil Nelson stain- 50% sensitive (Gives infectivity data

Question 19

What are the advantages and limitations of sputum culture for TB?

Answer 19

Most sensitive but takes time and requires skilled people

Question 20

What are the advantages and limitations of PCR for TB?

Answer 20

90% sensitive- can give false positives for current infection
Does not give all antibiotic sensitivities. Will show if rifampicin sensitive
Rapid

Question 21

What are the advantages and limitations of zeil Nelson stain for TB?

Answer 21

50% sensitive
Gives infectivity data- smear positive or smear negative
Rapid and cheap

Question 22

What does ‘smear positive’ imply?

Answer 22

TB and infectious

Question 23

What does ‘smear negative, culture positive’ imply?

Answer 23

TB and needs treatment but not infectious

Question 24

What would you see on a histology slide of someone with TB?

Answer 24

Multinucleating giant cell granulomas
Caseating necrosis
Sometimes visible mycobacterium

Question 25

What would you see on a CXR of someone with TB?

Answer 25

Upper lobe predominance Cavity formation and tissue destruction Scarring and shrinkage Heals with calcification- often in lymph nodes

Question 26

What is milliary TB?

Answer 26

Wide spread dissemination of mycobacterium TB via blood stream spread. Can rapidly be fatal

Question 27

What are the 4 drugs used to treat smear positive TB?

Answer 27

Rifampicin Isoniazid Pyrazinamide Ethanbutol

Question 28

If the patient becomes smear negative, what is the step down treatment?

Answer 28

Rifampicin | Isoniazid

Question 29

What are the side effects of rifampicin?

Answer 29

Colours urine and body fluids orange/pink Potent inducer of cytochrome enzymes => Breakdown of all steroids inc oral contraceptive => Breakdown of opiate analgesics

Question 30

What are the side effects of ethanbutol?

Answer 30

Optic neuritis- inflammation of the optic nerve- must ensure patients are not colour blind before treatment

Question 31

What are the side effects of izoniazid?

Answer 31

Hepatitis, renal failure and neuropathy | B6 deficiency and given peridoxine

Question 32

What is DOT and when is it used?

Answer 32

DOT = Directly observed therapy As compliance is poor you receive your medication at a pharmacy and must be supervised Used when you suspect medications not being taken

Question 33

When TB is diagnosed, who must be informed?

Answer 33

Public health for contact tracing

Question 34

Who must be detained in hospital in an infection control side room?

Answer 34

Anyone who is smear positive

Question 35

What is single drug resistant TB?

Answer 35

Resistant to izoniazid

Question 36

What is MDR TB and what are the consequences?

Answer 36

Resistant to izoniazid and rifampcin | Require injectables and 9-12 months of treatment

Question 37

What is XDR TB and what are the consequences?

Answer 37

Resistant to more than izoniazid and rifampcin Require injectables and quinalone for 9-12 moths Must be in a side room in infection control until better Form eastern Europe/ africa

Question 38

What happens if your newly Dx HIV positive and TB positive?

Answer 38

Treat viral load first and then TB within 8 weeks

Question 39

TB can be the first presenting symptom of someone with HIV. True or false?

Answer 39

True

Question 40

What is defined as latent TB?

Answer 40

Culture negative and symptom free | May have calcifications/ granlomas on the CXR

Question 41

What can cause reactivation of latent TB?

Answer 41

Steroids and immunosupressive drugs

Question 42

What are the tests for previous TB exposure?

Answer 42

Tuberculin skin test/Mantoux test | Interferon gamma release assay (blood test)

Question 43

How does the interferon gamma release assay work?

Answer 43

Blood test which looks for the interferon gamma specific antigen only found in mycobacterium TB It doesn't react with BCG which is an attenuated strain of M bovis

Question 44

How does the mantoux test work?

Answer 44

Intradermal injection of tuberculin- checking for skin reaction. Delayed type 4 hypersensitivity Cannot distinguish between latent TB, cured TB, active TB and BCG

Question 45

How is latent TB treated?

Answer 45

Can be treated or untreated. Must be treated if you want to give anti-TNF drugs Treatment = 6 months izoniazid OR 3 months izoniazid and rifampcin

Question 46

How is TB prevented

Answer 46

Contact tracing and screening of high risk sub groups Isolation of infectious cases BCG immunisation- most effective in neonates of high risk families Social measures- housing and nutrition

Question 47

Who might you want to give anti-TNF drugs to and therefore need to treat their latent TB?

Answer 47

Anyone with rheumatoid's, Crohn's, Psoriasis or ankylosing spondylytis

Question 48

What is in the BCG vaccine?

Answer 48

Attenuated strain of M bovis

Question 49

When people are on TB treatment, what should be monitored?

Answer 49

Liver function | Kidney function?