Pathogenesis of TB Flashcards
(36 cards)
What is tuberculosis?
a contagious, debilitating (consuming) bacterial disease
spread by airborne droplet nucleii from an infected person
What bacterium causes TB?
mycobacterium tuberculosis
What are symptoms of tuberculosis?
- 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
How does the cough in tuberculosis progress?
Initially mild non-productive
later is productive
haemoptysis
What are the symptoms like in latent TB infection compared to active TB disease?
-Latent TB has no symptoms
-Active TB has symptoms
How infectious is TB when comparing between latent TB infection and active TB disease?
-In latent TB infection, you cannot spread TB to others
-In active TB disease, it my spread TB to others
What is the comparison between in tests between latent TB infection and active TB disease?
-Latent TB infection usually has a positive skin test for quantiFeton-TB gold test
-Active TB disease usually has a positive skin test
What is the comparison between x-ray in latent TB infection and active TB disease?
-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
What are BCG’s ineffective for in latent TB?
BCG largely ineffective for adult pulmonary disease
What are the risk factors for reactivation of TB?
- Malnutrition
- Poverty
- Immunosuppression
- Diabetes
- Old age
- Poor health
- HIV
What does an initial infection with mycobacterium tuberculosis produce?
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
Why is granulomatous involvement of peribronchial and/or hilar lymph nodes frequent in primary tuberculosis?
Granulomatous involvement of peribronchial and/or hilar lymph
nodes is frequent in primary tuberculosis due to lymphangitic
spread from the Ghon focus.
What constitutes the Ghon complex?
The early Ghon focus together with the lymph node lesion
constitute the Ghon complex.
What do the lesions in the Ghon complex undergo over time and what does this lead to?
These lesions undergo healing and over time usually evolve to
fibro-calcific nodules.
What may follow primary infection of TB or reactivated TB?
Miliary TB
What is seen in miliary TB?
Lung, enlarged lymph nodes
(part of original Ghon complex)
are seen, plus miliary tubercles in lung parenchyma
When does miliary TB typically occur?
Miliary tuberculosis, as seen here, typically occurs when resistance to mycobacterial infection
is poor and often in children as consequence of primary disease
What object is typically present in miliary tuberculosis?
The small millet seed sized granulomas in this lung are typical for miliary tuberculosis
When can cause second degree intestinal TB?
Intestinal tuberculosis can be
2º to pulmonary TB from
swallowed infected sputum
What causes first degree intestinal TB?
1º intestinal TB develops in
people who drink milk
infected with M. bovis
How does TB in brain and meninges present?
- Thickened and opaque meninges
-Small tubercles are present within the brain
In what category were the characteristic of TB in brain and meninges common and in whom are they rarely seen?
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
What is potts disease?
A form of musculoskeletal tuberculosis
What is scrofula?
TB of the neck leading to swollen lymph node
