Tuberculosis Flashcards
What are the details of Mycobacterium tubercolisis?
Obligate aerobe, Rod shaped, airbourne
What is the aetiology of TB?
Acid fast
Slow growth rate
Sensitive to heat and UV
Non-motile
What are TB risk factors?
Immunodeficiency Very young + old Recent infection Close contact with TB case Living with close contacts
What are the 2 types of TB infection?
Latent - no signs or symptoms, non-infection, +ve test
Disease - Primary infection or latent activation, infectious, symptomatic
How is TB diagnosed?
Skin test (Mantoux) Cultures Bloods Molecular testing Imaging
What happens in the mantoux test?
0.1ml of tuberculin derived protein is injected into the forearm
=ve test if reactive reddened area is 5mm< between 48-72H
What happens with the cultures?
3x sputum analysis taken early morning
Should see slender rods
What is tested for in the blood tests?
IFNy - it is released by host in defence 24h test (quick) Expensive
What happens in the molecular testing?
Nucleic acids are amplified to identify the specific bacteria
very expensive
What can be ordered for imaging?
Pulmonary TB - X-ray/CT
Pleural TB - X-ray/bronchoscopy
Lymph node TB - US/CT/MRI
CNS TB - CT/MRI
What are the common symptoms of TB?
Persisten cough Constant fatigue Weight loss Loss of appetite Fever Haemoptysis Night sweats
What happens in Granulomatous inflammation?
Body attempts to section off the infected part
Necrosis in the core
Macrophages begin to form epithelium around the necrotic core
Collagen is deposited around the tissue
ROS produced in core
Yellow/white bad smelling amorphous cells in necrotic core
How is TB transmitted?
Airbourne - cough/sneeze/breath
What is the inflammatory response to TB?
Initial macrophage engulfment –> IL-12+18 secreted, IFNy induces bacterial killing, TNFa controls growth of TB
What is a Ghon focus/complex?
Focus - Primary lesion of granulomatous formation
Complex - Focus + infection of local lymphatics + hilar lymph nodes
