Tuberculosis

Question 1

What is the bacteria behind TB?

Answer 1

Mycobacterium tuberculosis

Question 2

What is primary tuberculosis?

Answer 2

• A non-immune host may develop a primary infection
• A Ghon focus first develops

Question 3

What is a ghon focus?

Answer 3

Ghon focus is composed of tubercle-laden macrophages

Question 4

What is a ghon complex?

Answer 4

Ghon focus and hilar lymph nodes

Question 5

What is secondary tuberculosis?

Answer 5

Reactivation of initial infection

Question 6

Where are extra-pulmonary sites of TB infection?

Answer 6

Central nervous system (tuberculous Meningitis - the most serious complication)
Vertebral bodies (Pott’s disease)
Cervical lymph nodes (scrofuloderma)
renal
gastrointestinal tract

Question 7

What is the most serious complication of TB?

Answer 7

Meningitis

Question 8

What is scrufuloderma?

Answer 8

Cervical lymph nodes elevated by TB

Question 9

What is Pott’s disease?

Answer 9

Disseminated TB - in vertebral bodies

Question 10

What is the screening test for Tuberculosis ?

Answer 10

Screening test for latent TB:
- Mantoux

Question 11

What does a montoux of diameter < 6mm mean?

Answer 11

Negative result

Demonstrates no hypersensitivity to tuberculin protein

Patient should be offered BCG

Question 12

What does a montoux diameter of 6-15 mm mean?

Answer 12

Positive results

Demonstrates hypersensitivity to tuberculin protein

Question 13

How should you manage a patient with positive monteaux test and a positive interferon gamma? - patient is asymptomatic

Answer 13

Treatment for latent TB

Question 14

What is the treatment for latent TB?

Answer 14

3 months of isoniazid (with pyridoxine) and rifampicin
OR

6 months of isoniazid (with pyridoxine)

Question 15

What is the treatment of meningeal tuberculosis?

Answer 15

Prolonged treatment of 12 months

Question 16

What is treatment for active TB?

Answer 16

Initial phase:
First two months - RIPE

Rifampicin
Isoniazid
Pyrazinamide
Ethambutol

Continuation phase: next 4 months
- Rifampicin
Isoniazid

Question 17

What is a general complication of TB treatment?

Answer 17

Immune reconstitution disease
occurs typically 3-6 weeks after starting treatment
often presents with enlarging lymph nodes

occur in HIV positive patients when starting anti-retrovirals; this is an immune phenomenon that results in the clinical worsening of a pre-exisiting opportunistic infection e.g TB

Question 18

What should be added in treatment of tuberculosis meningitis?

Answer 18

Steroids

Question 19

What causes cause false positive for a tuberculin skin test?

Answer 19

miliary TB
sarcoidosis
HIV
lymphoma
very young age (e.g. < 6 months)

Question 20

What test should be done if Mantoux test is positive? - why additional test? - what does it mean if both positive and no symptoms?

Answer 20

Interferon gamma
As Mantoux has false negatives
Test would mean latent tb diagnosis if both positive

Question 21

What is the mechanism by which TB Mantoux test works?

Answer 21

Interferon gamma

type IV (delayed) hypersensitivity reactions. These are largely mediated by interferon-γ secreted by Th1 cells which in turn stimulates macrophage activity.