Mycobacteria and Tuberculosis

Question 1

Where does tuberculosis affect?

Answer 1

Mainly lungs

Can affect: lymph nodes, bones, joints and kidney

Question 2

What is mycobacterium tuberculosis?

Answer 2

Obligate aerobes - facultative intracellular parasite

Question 3

How do you get TB?

Answer 3

Spread in droplets coughed/sneezed into air

Frequent or prolonged contact w/ infected person is needed

Question 4

What groups are most at risk of catching TB?

Answer 4

Damaged T cell immunity

Unhealthy, overcrowded conditions

Question 5

What is primary TB and how do you get it?

Answer 5

Droplet nuclei inhaled taken up by alveolar macrophages
Activation of T cell immunity wall off = forms granuloma = ghon focus
Enlarged lymph nodes and GF = primary complex

Question 6

What is secondary TB and how does it occur?

Answer 6

Reactivation of dormancy mycobacteria (impaired immune function) (mostly at apex at lung as highly oxygenated)
Cause caseous cente of tubercles to liquefy - organism can grown rapidly
Large Ag load
Bronchi walls become necrotic and rupture
Cavity formation

Question 7

What would you expect to see in TB infection compared TB lung disease?

(Organism, tuberculin skin test, chest x-ray, sputum smear, sputum culture, symptoms, infectious, case of TB?)

Answer 7

TB infection
- Organism present, positive skin test, normal chest x-ray, -ve sputum smear and culture, no symptoms, not infections and not defined case TB

TB Lung Disease
- Organism present, +ve skin test, lesion seen chest x-ray, sputum culture and smear +ve, symptoms present, infectious, defined as case TB

Question 8

Symptoms of TB?

Answer 8

Cough +- sputum, cough up blood, weight loss, swollen gland, fever, night sweat, feeling tired

Question 9

Tx TB?

Answer 9

RIPE - 2 months, followed RI for 4 months 
Rifampicin
Isoniazid 
Pyrazinamide
Ethambutol

Question 10

Role of vitamin D in TB?

Answer 10

Vitamin D activates macrophage which can destroy mycobacteria

Question 11

What is BCG?

Answer 11

Protection restricted to childhood tuberculosis - rarely infectious
Invalidate tuberculin skin test

Question 12

Link between HIV and TB?

Answer 12

HIV increase risk of acquiring TB - destroy immune system

Question 13

Diagnosis TB?

Answer 13

1. Chest x-ray
2. Tuberculin skin test
3. T-Spot TB - blood test to replace tuberculin test - detect reactive T cell
4. Microscopy - Ziehl-Neelson stain
5. Sputum culture - Lowenstein-Jensen medium (4-6 week visible colonies)
6. Automated culture - MGIT - fluorescent