S1 - Tuberculosis Flashcards
What is the bacterium responsible for TB infections?
Mycobacterium tuberculosis
What percentage of the world population is infected with latent TB today?
What percentage of those infected with latent TB will become sick with active TB at some point in their lifetimes?
33%
10%
How is TB spread?
What body system does it most commonly infect? Can it infect other systems?
Respiratory droplets (Airborne transmission)
Respiratory system
Yes, TB can disseminate to organs other than the lungs
What is Milliary TB?
Many small areas of local TB spread throughout an organ
What human cell in the respiratory tract is preferentially infected by TB bacterium?
Alveolar macrophages
After alveolar macrophages are infected by TB bacterium, what happens?
Immune cells surround the area, promote inflammation, and accumulate as dead cells
(This forms nodules called granulomas)
Does the immune system usually manage to wipe out all the TB bacterium on its own?
No, the immune system usually only manages to keep the bacterium at bay
(This is called latent TB and is true for 90% of infected individuals)
What is it called when a latent TB becomes active?
Reactivation
How is TB diagnosed?
The Mantoux Tuberculin test (TB antigen injected under the skin) and chest x-rays
What is a Gohn focus?
A TB granuloma large enough to be seen on x-ray
What is it called if a patient presents with a Gohn focus and regional lymph node involvement?
This is a Gohn complex
What is the difference between primary vs. secondary TB infection?
Primary infection is the initial host encounter with TB bacterium.
A secondary infection refers to EITHER being infected with TB after being cured OR reactivation of latent TB
What are the signs/symptoms of TB infection?
Fever, cough, bloody sputum, weakness, and chest pain.
What is the most common cause of death among AIDS patients?
TB
How is TB treated?
- 2 initial months of chemotherapy (antibiotics) and varying amounts of continuing treatment (No need to memorize drug names, but know it’s a drug cocktail given for months).
- Patients may be asked to take a complex regimen of drugs including:
Isoniazid (an anti-metabolite)
Rifampin (inhibits RNA polymerase)
Ethambutol (inhibits cell wall formation)
Pyrazinamide (converts to an acid and accumulates, killing the cell).
