TB

Question 1

How is TB spread?

Answer 1

Airbourne droplets

Question 2

Which form of TB is infectious?

Answer 2

Pulmonary

Question 3

What kind of pathogen is TB and who can it infect?

Answer 3

Obligate pathogen

Can infect a number of animals but humans are the principle host

Question 4

How is TB characterised in terms of bacilli or cocci?

Answer 4

Slender, straight or slightly curved aerobic acid fast bacilli
Non-motile, non-encapsulated and do not form spores

Question 5

Describe how TB is contracted.

Answer 5

• Airbourne droplet is inhaled and can reach distal airways
• Alveolar macrophages ingest TB where it then replicates
• Spreads via lympathics to hilar lymph nodes
• Granuloma formation occurs by activated T lymphocytes and macrophages

Question 6

What are the symptoms of TB?

Answer 6

Breathlessness 
Cough productive of sputum
Haemoptysis
night sweats 
weight loss 
chest pain 
malaise

Question 7

What are the signs of TB?

Answer 7

Upper zone crackles (aerobic organism and most O2 here)
Reduced chest expansion
dull to percussion
bronchial breathing

Question 8

Pulmonary TB is defined as active TB affecting any of..?

Answer 8

Lungs
pleural cavity
mediastinal lymph nodes
larynx

Question 9

What is the most common test for the diagnosis of TB?

Answer 9

AFB test with Z-N stain

Question 10

What are the outcomes of the Z-N stain of TB?

Answer 10

“smear positive” = patient infectious and usually needs isolated
“smear negative” = less infectious and no need for isolation

Question 11

Why is gram stain not used in the diagnosis of TB?

Answer 11

It has a thick waxy outer coat so does not take up any stain

Question 12

What else can be used to diagnose TB if uncertainty remains following Z-N stain?

Answer 12

Bronchoalveolar lavage - wash out fluid of air spaces and collected for examination

Question 13

What are key signs of TB seen on CXR?

Answer 13

upper lobe predominance 
caseating granulomas 
tissue necrosis 
scarring and shrinkage 
TB heals with calcification which can be seen as bright white areas on CXR

Question 14

Which antiobiotics are given for 2 months following diagnosis of TB?

Answer 14

Rifampicin
Isoniazid
Pyrazinamide
Ethambutol

Question 15

After 4 months antibiotic treatment, which 2 antibiotics are continued for a further 4 months?

Answer 15

Rifampicin

Isoniazid

Question 16

Which TB antibiotic colours urine and all bodily fluid orange as a side effect?

Answer 16

Rifampicin

Also SE: rashes and hepatoxicity

Question 17

What side effect can Isoniazid have?

Answer 17

peripheral neuropathy

Question 18

What side effect can Ethambutol have?

Answer 18

optic neuritis

Question 19

What is key to the treatment of TB?

Answer 19

Compliance with antibiotics as TB can become very resistant

Question 20

Is there any follow up treatment?

Answer 20

CXR at the end of the therapy

Question 21

What tests can be used to test for previous exposure to TB?

Answer 21

• Interferon Gamma Release Assay (blood test)
• Mantoux (Tubercillin) skin test - detects exposure to TB and BCG - cannot distinguish between latent, cured, active TB and BCG vaccination

Question 22

What are risk factors for TB?

Answer 22

Indian subcontinent, Pakistan 
HIV
Poverty 
Steroids, chemo, anti TNF therapy
smoking

Question 23

How can TB be prevented?

Answer 23

contract tracing 
screening of high risk groups 
isolation of infectious cases 
BCG vaccination 
Social measures - improve housing and hygiene

Question 24

If you have TB what must you be tested for?

Answer 24

HIV - goes with TB, so if TB then tested for HIV and if HIV then CXR to see if TB

Question 25

Which drugs can reactivate latent TB?

Answer 25

Steroids

immunosuppressant drugs