Tuberculosis

Question 1

What is the clinical presentation of TB?

Answer 1

Slow to resolve chest infection
Haemoptysis
Weight loss
CXR abnormalities

Question 2

Does TB affect upper or lower lobes?

Answer 2

Tends to affect upper lobes

Question 3

Why are mycobacteria bacilli considered to be alcohol and acid fast bacilli?

Answer 3

They retain dye even after exposure to acid and alcohol whereas other bacteria don’t.

Question 4

How does TB appear on a Ziehl-Neelsen (ZN) stain?

Answer 4

The mycobacteria appear as red dots. However, this does not give any indication of sensitivity or species.

Question 5

How long does PCR testing for TB take?

Answer 5

1-2 hours

Question 6

Why is PCR testing useful?

Answer 6

Fast

Gives some indication of species and sensitivity

Question 7

Why is culture on Lowenstein-Jensen medium still important despite the slow growth time?

Answer 7

Best sensitivity to TB and gives information on antibiotic sensitivity.

Question 8

What are the four drugs used to treat TB?

Answer 8

Rifampicin
Isozianid
Pyrazinamide
Ethambutol

Question 9

Why must an eye test be given before administration of ethambutol?

Answer 9

May cause optic neuritis and blindness. Patients must report any difficulties or changes in vision after starting this drug. LFTs must also be checked.

Question 10

Which drug causes yellow body fluids?

Answer 10

Rifampicin

Question 11

Which two drugs are only taken for two months?

Answer 11

Pyrazinimide

Ethambutol

Question 12

What is the only form of TB that is infectious?

Answer 12

Pulmonary

Question 13

How is TB spread?

Answer 13

Airborne droplets containing TB

Question 14

How is the spread of TB infection halted in the lungs?

Answer 14

Granuloma formation occurs through cell-mediated immunity by activated T-lymphocytes and macrophages
This gives rise to the latent disease - the disease may never become active

Question 15

Why does latent TB become active?

Answer 15

Will not become activated unless there is a deficiency in cell-mediated immunity
Active disease presents when a host’s immune response cannot contain MTB replication

Question 16

What is the definition of pulmonary TB?

Answer 16

Pulmonary TB is defined as active TB that is affecting any of the following: 
Lungs 
Pleural cavity 
Mediastinal lymph nodes 
Larynx

Question 17

What does a “smear positive” test on a Zheil-Neehlson stain indicate?

Answer 17

Acid fast bacilli - patient is therefore potentially infectious and usually needs to be kept isolated