TB

Question 1

clinical features of pulmonary TB

Answer 1

• may be silent
• cough, sputum, weight loss, night sweats, haemoptysis, malaise

Question 2

miliary TB

Answer 2

• occurs following haematogenous dissemination
• CXR; nodular opacities
• poor prognosis

Question 3

primary TB

Answer 3

• First infection with MTb
• Macrophages phagocytose bacilli, it survives inside the macrophage and proliferates creating localised infection
• Most people at this stage are asymptomatic
• There is a delayed hypersensitivity reaction (about 3 weeks in) to bacilli proliferating inside macrophages, resulting in tissue necrosis and formation of a granuloma
• Granulomatous lesions consist of a central area of necrotic material (caseation – cheese like necrosis), surrounded by granulomatous inflammatory response. They exhibit fibrosis
• Caseated areas heal and many become calcified, some of these calcified nodules contain bacteria where the bacilli can lie dormant for many years

Question 4

where does primary infection also spread to

Answer 4

nearby hilar lymph nodes

Question 5

what is the primary TB lesions termed

Answer 5

Ghon focus

• small calcified nodule in the mid zone of the lung

Question 6

2y TB

Answer 6

• majority of cases
• immune system contains infection
• associated with immunosuppression etc

Question 7

what lesion is associated with 2y TB

Answer 7

Assmann focus

• Apical lesion that begins as a small caseating granuloma
• Similar histopathology to Ghon focus

Question 8

diagnosis of latent TB

Answer 8

mantoux test

Question 9

why may mantoux be false negative

Answer 9

patient has had BCG vaccination

Question 10

PCR

Answer 10

allows identification of rifampicin and multi drug resistance

Question 11

what is IGRA positive in

Answer 11

current, latent and previous untreated TB

Question 12

IGRA

Answer 12

Quantification of how much gamma interferon is released from circulatory T cells in response to specific stimulus e.g. MTB

Question 13

which type of hypersensitivity reaction is it

Answer 13

IV

Question 14

CXR

Answer 14

may be normal bilateral hilar enlargement consolidation, cavitation, fibrosis and calcification

Question 15

histology hallmark

Answer 15

caseating granuloma

Question 16

risk factors

Answer 16

anti-TNF alpha therapy can cause reactivation of latent TB

Question 17

treatment for meningitis (CNS) affected

Answer 17

2 RIPE 10 RI

Question 18

rifampicin AE

Answer 18

red/orange discolouration rash hepatotoxicity hepatitis

Question 19

isoniazid AE

Answer 19

peripheral neuropathy in sock and glove distribution paraesthesia

Question 20

pyrazinamide AE

Answer 20

anorexia and vomiting

flushing

joint pain

yellow skin or eyes

rash

hyperuricamia

Question 21

ethambutol AE

Answer 21

colour blindness optic neuritis

Question 22

three Ms

Answer 22

M tuberculosis M bovis M africanum

Question 23

M bovis cause what lesions

Answer 23

intestinal/tosillar

Question 24

M bovis

Answer 24

infect cows and killed by pasteurisation of milk