Mycobacterium tuberculosis

Question 1

type

Answer 1

Grows in long
parallel chains
“chords”
- aerobic
- Non spore
forming
- Acid fast

Question 2

transmission and risk factor

Answer 2

Highly
contagious
Droplet nuclei
Dust
Contagious AF

Question 3

cell wall layers

Answer 3

• Lipoarabinomannan
• Mycolic acid
• arabinogalactan
• peptidoglycan
• cytoplasmic membrane

Question 4

presentation

Answer 4

AIDS: 50-70% develop
extrapulmonary
infection(resistance to TB
dependent on subset of CD4+
T cells that produce
a-interferon

Question 5

pathogenesis

Answer 5

Intracellular survival in
alveolar macrophages
1. Sulfolipids: Prevent
oxidative burst & inhibit
phagosome-lysosome
fusion
2. Cell wall lipids,
lipoarabinomannan,
SOD: resist lysosomal
enzymes,ROS
LAM=LPS
3. Exochelins: secrete
siderophores
4. Mycolic acid: waxy,
doesn’t dry out but
sensitive to heat

Question 6

culture

Answer 6

require
enriched or
special medium
Lowenstein-Jens
en agar
Oleic
acid-albumin
broth
- grows slowly in lab 2-8 weeks

Question 7

microscopy

Answer 7

Ziehl-Neelsen
stain(acid fast
bacilli)
Rhodamine
Auramine
fluorescent stain

Question 8

prognosis

Answer 8

Multiple
combination
therapy
Prevention:
Prophylactic
antimycobact
erails

Question 9

vaccine

Answer 9

BCG(bacillus
calmette-Guerin)
vaccine
Attenuated
M.bovis
strain