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36 Cards in this Set

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What virus is driving the Tb epidemic? Where is this localized to?
HIV/AIDS

Africa
What stain is used for a histologic diagnosis of Mycobacterium?
Acid-fast
What is the morphology of Mycobacterium?
Bacilli
What are the three unusual features of Mycobacterium?
Slow growing; take 8 weeks to grow!

Obligate aerobes

Mycolic acid in the cell wall; gives resistance
What occurs when Mycobacterium is in a low oxygen state?
Enter a quiescent state and are resistant to cidal antimicrobials
What are the layers within the M. tuberculosis cell wall?
Outer to inner:
Capsule
Mycolic acid
Peptidoglycan/Arabinogalactan
Inner membrane
What are the two enzymes involved in the biosynthesis of the mycolic acid in Mycobacterium that are targeted by antibiotics?
KatG
InhA
What is the activity of KatG?
Catalase/peroxidase

Required for clinical activity of Isonazid
What is the activity of InhA?
Synthesis of long chain mycolic fatty acids.

Targeted by Isoniazid
What type of immunity is essential in controlling Tb infections?
Cell-mediated immunity
Primay Tb will show what signs on PPD and xray?
PPD: +
Xray: -
Where is the first place that Mycobacteria localizes to in the body?
Albeolar macrophages (dust cells)
What is the mechanism by which Mycobacterium tuberculosis survives within macrophages?
Blocking of P-L fusion.

No acidification; the cells can't be killed.
What does Mycobacterium tuberculosis do while inside the phagolysosome?
Shed lipids that are presented to the body.

Are able to get out of the cell and stimulate the immune system.
What response is mycolic acid alone able to generate?
Granuloma formation in the host.

Sufficient for virulence.
What is the function of TNF-alpha in Mycobacterium tuberculosis infection?
Recruitment of macrophages

Stabilization of the granuloma
What kind of lymphocyte is active in Mycobacterium tuberculosis infection?
CD4 TH1 cells
What interleukin is produced by this T cell in Mycobacterium tuberculosis infection?

What is its activity?
IL-2

Stimulation of CD8 cytotoxic T-cell development
What lymphokine is released by CD4 cells in T-cell Mycobacterium tuberculosis infection?

What is its activity?
INF-gamma

Activation of macrophages
What molecules are released by activated macrophages in Mycobacterium tuberculosis infections?

What is their activity?
IL-1
TNF-alpha

Activation of a general immune response
What type of hypersensitivity reaction is active in Mycobacterium tuberculosis infections
Type IV

Delayed; involves macrophages
What is the activity of CD8 T cells in Mycobacterium tuberculosis infection?
Recognition and killing of infected macrophages
What is the mechanism of dispersion of Mycobacterium tuberculosis from the lungs?
Through regional lymph node
That is the appearance on PPD/Xray for latent/dormant Tb?
PPD +
Xray -
What is the most common form of Tb in the US?
Latent Tb
What is the effect of a weakening immune system on latent Tb?
RELEASE OF THE BACTERIA!!!
What are the Xray/PPD findings for active Tb?
PPD +
Xray +
SPUTUM +
Who are effected by disseminated/miliary Tb?
Immunocompromised
Old
Young
What is the mechanism of antigen presentation with Tb?

What is a complication with this?
MHCI

Can't really use vaccines
What type of secretion system do Mycobacterium tuberculosis use?
Type VI
What is used for a Tb vaccine?
Bacille Calmette Guerin

Avirulent strain of Tb from cows.

NOT SAFE IN IMMUNOCOMPROMISED
What disease does Mycobacterium leprae cause?
Leprosy
What is the reservoir for Mycobacterium leprae?
Humans
What is the transmission of Mycobacterium leprae?
Person to person via secretions, aersols.

Significant amounts of contact necessary
What is the appearance of a Mycobacterium leprae infection?
Skin lesions.
What type of Mycobacterium is found all over the place and has been implicated in infections in severely immunocompromised hosts?
Mycobacterium avium complex