tuberculosis

Question 1

what is tuberculosis

Answer 1

a granulomatous caseating disease caused by mycobacteria

Question 2

describe mycobacteria

Answer 2

• aerobic
• non-motile
• non-sporing
• slow growing bacilli
• thick waxy capsule
• Resistant to phagolysosomal killing and able to remain dormant

Question 3

what is mycobacterium tuberculosis complex

Answer 3

4 species of mycobacteria that are TB causing
1. M tuberculosis
2. M africarium
3. M microtis
4. M bovis

Question 4

where is TB very common

Answer 4

africa and south asia

Question 5

how does TB spread

Answer 5

spread via respiratory droplets as it is an airborne infection

Question 6

risk factors for TB

Answer 6

• travel to associated country
• immunocompromised eg HIV
• homeless/crowded housing
• IVDU
• smoking+alcohol
• increasing age

Question 7

pathophysiology of TB

Answer 7

1. Alveolar macrophages ingest the bacteria, but the bacteria resist being killed so a granuloma forms.
2. T-cells are recruited and surround the granuloma. The central part of the granuloma undergoes necrosis and has a cheese-like appearance = caseating granuloma which is referred to as a primary ghon focus.
3. The ghon focus spreads to nearby lymph nodes. Ghon focus + lymph node spread = ghon complex.
   If TB spreads systemically it is referred to as miliary TB.
4. Most often it is contained within the granuloma but stays alive so known as latent TB.

Question 8

does latent TB have symptoms

Answer 8

no it is asymptomatic

Question 9

systemic symptoms of TB

Answer 9

• Weight loss
• Low grade fever
• Anorexia
• Drenching night sweats
• Malaise

Question 10

pulmonary symptoms of TB

Answer 10

• Productive cough
• Haemoptysis
• Cough >3 weeks (dry or productive
• Breathlessness

Question 11

extrapulmonary symptoms of TB

Answer 11

• meningitis
• skin changes
• TB pericarditis
• joint pain

Question 12

signs of TB

Answer 12

• Dullness to percussion
• Decreased breathing
• Fever
• Crackles

Question 13

3 main investigations for TB

Answer 13

1. chest x ray
2. sputum culture
3. biopsy

Question 14

what is the sputum culture to diagnose TB

Answer 14

sputum culture for acid-fast bacilli:

– Ziehl-Neelsen stain -> turns red/pink

Question 15

how to diagnose latent TB

Answer 15

• Tuberculin skin test ‘Mantoux’
• Interferon gamma release assay

Question 16

treatment of TB

Answer 16

RIPE
1. rifampacin
2. isoniazid
3. pyrazinamide
4. ethambutol

Question 17

how long is rifampacin given for TB and what are the side effects

Answer 17

approx 6 months

red/bloody urine (haematuria)

Question 18

how long is isoniazid given for TB and what are the side effects

Answer 18

approx 6 months

peripheral neuropathy

Question 19

how long is pyrazinamde given for TB and what are the side effects

Answer 19

approx 2 months

hepaptits, gout

Question 20

how long is ethambutol given for TB and what are the side effects

Answer 20

approx 2 months

eye problems - optic neuritis