Tuberculosis Flashcards
Describe the Microbiology of Mycobacterium Tuberculosis
- Rod shaped
- Strict aerobe
- Mycolic acid cell wall
- Acid-fast (Red on Zeihl-Neeson stain)
What three tests can be performed to confirm Tuberculosis?
- Mantoux test
- Heaf test
- Interferon gamma release assays (IGRA)
How is Tuberculosis transmitted?
Respiratory spread (inhalation)
How can Mycobacterium invade host defences and cause a Primary TB infection?
Mycobacterium is engulfed by Alveolar macrophages, however TB can evade lysosomal degradation and proliferate within the alveolar macrophages
What is a Ghon focus?
A caseating granuloma in a TB infection
What is a Ghon complex?
A Ghon focus which has infiltrated associating lymphoid tissue
Where do Ghon complexes tend to occur?
Subpleura and lower lobes of the lungs
What is a Ranke complex?
Ghon complexes which have undergone fibrosis and calcification
Under what circumstances might a Latent TB infection reactivate to Symptomatic TB?
In aging / AIDS
How might Systemic Miliary TB affect the Kidneys?
Sterile pyuria; WBCs in urine
How might Systemic Miliary TB affect the Lumbar vertebae?
Pott disease
How might Systemic Miliary TB affect the Meninges of the brain?
Meningitis
How might Systemic Miliary TB affect the Adrenal glands?
Addison’s disease (Primary adrenal insufficiency)
How might Systemic Miliary TB affect the Liver?
Hepatitis
What is the treatment for TB? What is the duration for each drug?
2 antibiotics: Isoniazid and Rifampicin (6 months)
2 additional antibiotics:
Pyrazinamide and Ethambutol (2 months)
What cells are found in a Granulomatous conditions of a TB infection?
Giant Langerhan cells
Which regions of the lungs does TB infect? Why?
Upper lobes, because O2 levels are higher here
What is Alectasis?
Collapse of a lung or lobe of a lung, when alveoli within the lung become deflated
What group(s) of people are at risk of developing TB?
- Urban poor
- Alcoholics
- IVDU
- Homelessness
- Prison inmates
What is Interferon Gamma alpha?
IFG-a is released from T-helper lymphocytes in response of Mycobacterium tuberculosis
Of all the TB medications, which one turns urine orange / red?
Rifampicin
What is Multi-drug resistant TB defined as?
Resistance to Isoniazid and Rifampicin
What is Extreme Multidrug Resistance TB defined as?
Resistance to Isoniazid and Rifampicin
And…
Resistance to any fluoroquinoline, and one of three injectable second line drugs
What is the mechanism of action for Isoniazid?
Mycolic acid synthesis inhibitor
What is the mechanism of action for Rifampicin?
DNA-dependent RNA polymerase inhibitor
What is the mechanism of action for Ethambutol?
Mycolic acid synthesis inhibitor
What is the mechanism of action for Pyrazinamide?
- Fatty acid synthesis inhibitor
- Membrane disruption
- Trans-translation inhibitor
