17 Tuberculosis Flashcards Preview

3 Respiratory Unit > 17 Tuberculosis > Flashcards

Flashcards in 17 Tuberculosis Deck (16)
Loading flashcards...
1

What bacteria causes tuberculosis?

Mycobacterium tuberculosis

2

TB bacili are aerobic, acid and alcohol fast bacili. How are they stained and cultured? How long does it take?

Ie what method and what medium

Stained: Ziehl-Nielsen method 

Culture: Lowenstein-Jensen medium

How long?: 2-6 weeks to culture

3

How is TB transmitted? (ie in what form are the TB) 

Infected droplets

4

A patient with pulmonary TB must be on anti-TB chemotherapy for 6 months. How long after commencing treatment is their sputum no longer infective?

2 weeks- infectivity of sputum= minimal

5

Who is particularly at risk of acquiring TB in the UK?

  • Non-UK born/recent migrants
  • Immunocompromised
    • Eg HIV, chemo
  • Homeless
  • Drug users, prisoners

(TB requires prolonged contact- likely to be someone you live with etc) 

6

How is a patient tested for a latent TB infection? (2) Explain how they work.

7

What % of people infected with TB will develop primary TB and what % will develop post primary TB? 

(post primary- up to 60 yrs post initial infection) 

8

Where (in the lungs) is post primary TB most often seen and why?

Upper lobes

Higher pO2 favoured by Mycobacteria

9

How does latent TB develop into active TB? (5)

  1. Cavity formation: 
    1. softening and liquefaction of caseous material- discharged into bronchus
    2. fibrous tissue forms around cavity BUT unable to limit extension of tuberculous process
  2. Haemorrhage:
    1. Caseous process extends into vessel walls 
      1. HAEMOPTYSIS
  3. Spread to involve rest of lung:
    1. Caseous and liquefied material- spread infection through bronchial tree
  4. Pleural effusion:
    1. TB bacili enter pleura/hypersensitivity reaction
  5. Miliary TB:
    1. Rupture of caseous pulmonary focus into blood vessel- widespread dissemination of bacili

10

What sites might be involved in extra pulmonary TB?

Lymph nodes, bones, joints, CNS, GI tract, urinary tract

11

How might a patient with TB present clinically?

Gradual onset (weeks/months)

Symptoms:

  • Tiredness
  • Malaise
  • Weight loss
  • Fever
  • Sweats
  • Cough
    • Dry/productive (w./ mucoid sputum)
    • Haemoptysis

Signs:

  • Crackles (maybe) 

12

What may be seen on a chest x-ray for a patient with TB?

  • Caviated solid lesions
  • Streaky fibrosis
  • Flecks of calcification

13

How is TB treated? (RIPE)

COMBINATION OF 4 ANTIBIOTICS - several months 

  1. Rifampicin
  2. Isoniazid (INAH) + (vitamin B6) 
  3. Pyrazynamide
  4. Ethambutol

all 4- for 2 months

rifampicin and isoniazid- for 4 months

14

Why is vitamin B6 given with INAH (isoniazid)?

To prevent preripheral nerve damage

15

Why are 4 drugs used to treat TB?

Single drugs would allow selection of resistant strains 

Unlilely that strains= resistant to all 4 drugs

16

Outline the pathophysiology of TB: