TB

Question 1

Where should a patient with TB be admitted?

Answer 1

negative pressure isolation room

AIRBORNE ISOLATION

Question 2

Where are the cavitations of TB seen & why?

Answer 2

in the upper lobe of the right lung

- because there is the most oxygen there due to low exchange there

Question 3

What should be excluded in case of any cavitation or consolidation in the bases of both lungs?

Answer 3

septic emboli until proven otherwise

- usually from right sided endocarditis

Question 4

What are the risk factors for TB?

Answer 4

• endemic country (india, pakistan, Saudi Arabia)
• jail
• IVDU
• smokers
• immunocompromised hosts
• HIV

Question 5

What is the pathogenesis of TB?

Answer 5

airborne transmission -> droplet nuclei
- exposure to infected person -> inhalation -> alveolar macrophage (high IFN-y) -> hard shell & inactivates TB (latent TB) -> diminished immune system -> reactivation of TB (common in adults)
OR
- alveolar macrophage unable to inactivate TB -> primary infection (common in children)

Question 6

How should u check for latent TB?

Answer 6

IFN-y assay

Question 7

What is the risk of reactivation of TB?

Answer 7

• 5% in the first 2 years
• 10% in a lifetime
• 10% every year in HIV

Question 8

What are the clinical features of pulmonary TB?

Answer 8

• constitutional symptoms
• chronic cough
• dyspnea
• hemoptysis

Question 9

What are the clinical features of extra pulmonary TB?

Answer 9

• pleurisy
• meningitis
• peritonitis
• lymphadenitis (cervical cold abscess)
• pericarditis
• vertebral (Pott’s disease)

Question 10

What investigations should be performed for pulmonary TB?

Answer 10

• CXR -> apical cavitation or any findings in HIV patients
• sputum AFB smear x3 with 8 hours in between
• sputum M. TB PCR
• sputum AFB culture (for 6 weeks)

Question 11

What investigations should be done for extrapulmonary TB?

Answer 11

• AFB smear
• M. TB PCR
• AFB culture

Question 12

What investigations have the highest sensitivity in diagnosis of TB?

Answer 12

1- AFB culture
2- M. tuberculosis PCR
3- AFB smear

Question 13

What are the phases of treatment of TB?

Answer 13

INDUCTION PHASE (2 months)

• isoniazid + vit B6
• rifampin
• ethambutol
• pyarzinamide

CONTINUATION PHASE (4-7 months)

• isoniazid + vit B6
• rifampcin

SCREEN ALL TB PATIENTS FOR HIV

Question 14

When can we discontinue airborne isolation?

Answer 14

when ALL are present

• 2 weeks of treatment
• 3 consecutive sputum AFB are negative (8 hours apart)
• improving respiratory symptoms

Question 15

What are the side effects of TB drugs?

Answer 15

• isoniazide -> hepatotoxicity, neurotoxicity due to B6 deficiency
• Rifampcin -> hepatotoxicity, gastritis, orange discoloration of body fluids
• ethambutol -> LEAST hepatotoxicity, optic neuritis
• pyrazinamide -> MOST hepatotoxic, hyperuricemia (gout), arthritis

Question 16

How should latent TB be confirmed?

Answer 16

positive PPD or positive interferon-gamma release assay (IGRA) + no symptoms + negative chest x-ray

• > 5mm -> HIV or recent contact with active TB
• > 10mm -> high risk congregate settings
• > 15mm -> no risks

Question 17

How is latent TB treated?

Answer 17

FIRST LINE: isoniazid + vit B6 + rifampentine weekly for 3 months
OR
- rifampcin daily for 4 months
- isoniazid + vit B6 daily for 9 months