TB

Question 1

What pathogen causes TB?

Answer 1

mycobacterium tuberculosis

Question 2

Pulmonary TB symptoms

Answer 2

persistent cough
weight loss
pyrexia (can be worse at night)
failure of antibiotic therapy
haemoptysis

Question 3

Extrapulmonary TB symptoms

Answer 3

depends on location
bone = pain at site
bowel = abdominal pain
nodal = swelling at site, pyrexial
CNS = focal neurology, headache
endometrial = amenorrhoea

Question 4

TB risk factors

Answer 4

ethnic minority groups
homeless
drug + alcohol abuse (associated with overcrowding, poor living conditions and malnutrition)
close contact with infected patient
immunosuppression
young or old age

Question 5

What would be seen on biopsy in TB?

Answer 5

caseating necrotising granuloma

Question 6

Describe how a sputum sample is collected and tested for TB?

Answer 6

3 morning samples
Ziehl-Neelsen staining (acid-fast bacilli staining)

Question 7

Typical drug regime for TB

Answer 7

Rifampicin, Isoniazid, Pyrazinamide, Ethambutol x2 months
then Rifampicin/isoniazid x4 months

Question 8

What is MDR-TB?

Answer 8

multidrug-resistant TB
resistant to Rifampicin and Isoniazid

Question 9

How is MDR-TB diagnosed?

Answer 9

culture of organism
DNA probe to check for Rifampicin + Isoniazid resistance

Question 10

How is contact tracing carried out for TB?

Answer 10

household contacts in all cases of pulmonary TB
<65 = Tuberculin test
>65 = CXR

Question 11

Who is screened for TB?

Answer 11

HIV patients
patients on immunosuppressant drugs eg. biologics
occupational health screening eg. healthcare workers

Question 12

Describe Tuberculin testing

Answer 12

purified protein derivative of TB
intradermal injection
mantoux single intradermal injection
indicates immune recognition of TB

Question 13

Describe IGRA for TB screening?

Answer 13

Interferon gamma releasing assays
IFN-Y released from primed T-lymphocytes when exposed to Tuberculin specific proteins
T-spot test
Qwantiferon-Gold test
not used for active case diagnosis

Question 14

What is latent TB? What tests will be +ve?

Answer 14

+ve Tuberculin test
+ve IGRA test
no evidence of active TB )eg. on CXR)
5-10% lifetime risk of active TB

Question 15

How is latent TB treated?

Answer 15

Rifampicin/Isoniazid or Isoniazid monotherapy

Question 16

How can TB be prevented?

Answer 16

seek out latent cases and treat
BCG vaccine (universal or selective)

Question 17

What does BCG stand for in BCG vaccine?

Answer 17

bacille calmette-guerin

Question 18

Describe BCG vaccination

Answer 18

intradermal vaccine
effective in children (prevents TB meningitis)

Question 19

Who is given the BCG vaccine in the UK?

Answer 19

targeted in areas where rate => 40/100000 where family born
given at birth (up to 4-6 weeks)

Question 20

nonName some atypical mycobacteria

Answer 20

M. Kansasii
M. Malmoense
M. Avium Intercellulare
M. Cheloneii
M. Marinum
M. Scrofulae
M. Abscessus

(also called non-tuberculous mycobacteria)

Question 21

What are some differences between TB and atypical mycobacteria?

Answer 21

non-tuberculous mycobacteria has:
- prolonged treatment
- lower cure rate, higher relapse rate
- non-notifiable
- diagnosis = 2 +ve sputum samples`

Question 22

Isoniazid side effects

Answer 22

peripheral neuropathy (pyridoxine given to prevent this)
liver toxicity

Question 23

Rifampicin side effects

Answer 23

liver toxicity
hepatic enzyme (p450) inducer
turns bodily fluids red/orange colour

Question 24

Ethambutol side effects

Answer 24

visual disturbance (colour blindness, loss of acuity etc)
avoid in chronic kidney disease

Question 25

Pyrazinamide side effects

Answer 25

liver toxicity

Question 26

Second line TB treatments (in drug-resistant cases)

Answer 26

amikacin
macrolides
quinolones
capreomycin