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Life protection > Pathogenesis of TB > Flashcards

Pathogenesis of TB Flashcards

1
Q

What is tuberculosis?

A

a contagious, debilitating (consuming) bacterial disease
spread by airborne droplet nucleii from an infected person

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2
Q

What bacterium causes TB?

A

mycobacterium tuberculosis

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3
Q

What are symptoms of tuberculosis?

A
  • A cough that will not go away
  • Feeling tired all the time
  • Weight loss
  • Loss of appetite
  • Fever – low grade
  • Night sweats
  • dyspnoea
  • Multi-organ dysfunction or adrenal insufficiency
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4
Q

How does the cough in tuberculosis progress?

A

Initially mild non-productive
later is productive
haemoptysis

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5
Q

What are the symptoms like in latent TB infection compared to active TB disease?

A

-Latent TB has no symptoms
-Active TB has symptoms

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6
Q

How infectious is TB when comparing between latent TB infection and active TB disease?

A

-In latent TB infection, you cannot spread TB to others
-In active TB disease, it my spread TB to others

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7
Q

What is the comparison between in tests between latent TB infection and active TB disease?

A

-Latent TB infection usually has a positive skin test for quantiFeton-TB gold test
-Active TB disease usually has a positive skin test

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8
Q

What is the comparison between x-ray in latent TB infection and active TB disease?

A

-Latent TB has a normal chest x-ray and negative sputum test
-Active TB has an abnormal chest x-ray, or positive sputum smear or culture

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9
Q

What are BCG’s ineffective for in latent TB?

A

BCG largely ineffective for adult pulmonary disease

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10
Q

What are the risk factors for reactivation of TB?

A
  • Malnutrition
  • Poverty
  • Immunosuppression
  • Diabetes
  • Old age
  • Poor health
  • HIV
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11
Q

What does an initial infection with mycobacterium tuberculosis produce?

A

Initial infection with Mycobacterium tuberculosis in an
immunocompetent individual usually occurs in an
upper region of lower lobe of the lung producing a lesion called
a Ghon focus

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12
Q

Why is granulomatous involvement of peribronchial and/or hilar lymph nodes frequent in primary tuberculosis?

A

Granulomatous involvement of peribronchial and/or hilar lymph
nodes is frequent in primary tuberculosis due to lymphangitic
spread from the Ghon focus.

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13
Q

What constitutes the Ghon complex?

A

The early Ghon focus together with the lymph node lesion
constitute the Ghon complex.

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14
Q

What do the lesions in the Ghon complex undergo over time and what does this lead to?

A

These lesions undergo healing and over time usually evolve to
fibro-calcific nodules.

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15
Q

What may follow primary infection of TB or reactivated TB?

A

Miliary TB

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16
Q

What is seen in miliary TB?

A

Lung, enlarged lymph nodes
(part of original Ghon complex)
are seen, plus miliary tubercles in lung parenchyma

17
Q

When does miliary TB typically occur?

A

Miliary tuberculosis, as seen here, typically occurs when resistance to mycobacterial infection
is poor and often in children as consequence of primary disease

18
Q

What object is typically present in miliary tuberculosis?

A

The small millet seed sized granulomas in this lung are typical for miliary tuberculosis

19
Q

When can cause second degree intestinal TB?

A

Intestinal tuberculosis can be
2º to pulmonary TB from
swallowed infected sputum

20
Q

What causes first degree intestinal TB?

A

1º intestinal TB develops in
people who drink milk
infected with M. bovis

21
Q

How does TB in brain and meninges present?

A
  • Thickened and opaque meninges
    -Small tubercles are present within the brain
22
Q

In what category were the characteristic of TB in brain and meninges common and in whom are they rarely seen?

A

This used to be a common complication in children with post-1 ̊ miliary
TB. It is rarely seen in people who have had BCG vaccination

23
Q

What is potts disease?

A

A form of musculoskeletal tuberculosis

24
Q

What is scrofula?

A

TB of the neck leading to swollen lymph node

25
Q

What is the food in immune response against TB?

A

*Innate immunity: alveolar macrophages kill ingested
bacilli
*Th1 adaptive immune response: CD8 and CD4 T cells,
IFN-gamma: essential for controlling infection

26
Q

What is the bad in immune response against TB?

A

Excessive immune response leads to overproduction of
TNF-alpha and healthy tissue damage by macrophages
(immunopathology of TB - granuloma).

27
Q

How does TB live inside of a host macrophage?

A
  1. Phagocytosis of mycobacteria
  2. Mycobacteria escapes into cytoplasm
  3. Mycobacteria inhibits phagosome-lysosome(PL) fusion and maintains early endosome. Also blocks acidification
28
Q

What does mycobacteria control and stop?

A

-Controls antigen presentation
–This stops recruitment of CTL’s and blocks macrophage activation

29
Q

In TB granuloma, what does containment of infection lead to?

A

Tissue damage

30
Q

What do TB granuloma consist of?

A

spherical collection of lymphocytes,
macrophages and epithelioid cells
with a small area of central
caseation necrosis

31
Q

What does the centre of a granuloma undergo and what does this to produce and why is this important?

A

The centre of the granuloma undergoes a combination of
liquefaction and coagulative necrosis producing caseous necrosis,
which is unique to TB and causes considerable tissue destruction to the host

32
Q

What is the mantoux test?

A

Method of determining whether an individual is infected with mycobacterium tuberculosis

33
Q

What does a positive mantoux test mean?

A

If there is a bump of a certain size at site of injection, it means there probably is mycobacterium tuberculosis present

34
Q

What is the blood diagnosis of pulmonary TB?

A

Interferon (IFN)-gamma blood test.
- T-cell response to Mtb proteins

35
Q

What is the sputum diagnosis of pulmonary TB?

A

cough or induced
- smear, culture,
- GeneXpert - PCR
Bronchoscopy - BAL
Biospy

36
Q
A

Life protection (12 decks)

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