Tuberculosis Flashcards
Tuberculosis as a g_____ c______ disease, caused by m_____
granulomatous caseating
mycobacteria
What are the 4 species known as mycobacterium tuberculosis complex? (MTC that cause TB)
M. tuberculosis
M africanum
M microti
M bovis
Where does M bovis come from?
Unpasteurised milk
Where is TB most common?
South Asia (China, India, Pakistan)
Subsaharan Africa
Approximately how many people worldwide have TB? (mostly latent)
1.7 billion
How is TB spread?
Airborne
What are risk factors for TB?
Country and travel eg to India
Immunocompromised eg HIV
Homeless/crowded housing
IVDU
Smoking
Alcohol
Age
Are mycobacteria tuberculosis complexes (MTC) motile?
No, non-motile
Are mycobacteria tuberculosis complexes (MTC) spore forming?
No, non-spore forming
Are mycobacteria tuberculosis complexes (MTC) slow growing?
Yes, 15-20 hours
Are mycobacteria tuberculosis complexes (MTC) susceptible to phagolysosome killing?
No, they are resistant due to mycotic acid capsule
Mycobacteria tuberculosis complexes (MTC) are acid-____ bacteria that have a thick, waxy wall that is resistant to most staining methods.
acid-fast
What stain turns mycobacterium tuberculosis bright red?
Ziehl-Neelsen stain
The waxy cell wall of mycobacterium tuberculosis also makes it resistant to weak d_____
disinfectants
True or false: Mycobacterium tuberculosis needs oxygen to survive
True, strict aerobe
What happens when an alveolar macrophage engulfs m. tuberculosis?
Bacteria produces a protein preventing the lysosome fusing to the vesicle containing the bacteria, so it can’t break it down. Proliferates causing a localised infection = primary tuberculosis
What are symptoms of primary tuberculosis
Most asymptomatic
Some have flu-like symptoms
How long after initial infection of m tuberculosis for cell-mediated immunity to kick in?
around 3 weeks
What is the cell-mediated immune response to primary tuberculosis?
Immune cells surround TB infection, forming granuloma to wall off and prevent it spreading
What does caseous necrosis refer to in TB?
The tissue in the middle of the granuloma dying
caseous = cheese-like as dead tissue looks soft and white like cheese