Term
| Why are mycobacterium acid fast? |
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Definition
| Mycobacterium are acid fast because they have a mycolic acid layer |
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Term
| What are the two types of granulomas? |
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Definition
Foreign and Immune
Immune granulomas occur in the presence of non-degradable antigens where T-cells produce cytokines that transform macrophages into epitheliod cells and multinucleate giant cells |
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Term
| TB, Leprosy, Syphillis, and Cat Scratch Disease are all examples of granulomatous inflammation. What are their causative agents? |
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Definition
TB: Mycobacterium tuberculosis
Leprosy: Mycobacterium leprae
Syphillis: Treponema pallidum
Cat Scratch Disease: Bartonella henselae |
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Term
| Name a few extra components one would find in a mycobacterial cell wall besides the typical Gram+ parts. |
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Definition
Lipoarabinomannan (LAM)
Arabinoglactans
Mycolics Acids
Transport Proteins and Porins
(these act as antigens) |
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Term
| You have recieved a culture of mycobacteria from a new patient and notice that they may either have photochromogens or scotochromogens. What does this mean? |
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Definition
The patient does not have tuberculosis.
M. tuberculosis complexes are nonpigmented or buff colored. |
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Term
| Is M.tuberculosis a facultative or obligate intracellular organism? |
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Definition
| M. tuberculosis is a Facultative Intracellular Organism |
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Term
| Explain why TB cannot be killed by macrophages. |
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Definition
TB blocks Early Endosomal Autoantigen 1 (EEA1) which is needed for phagolysosomal fusion.
It also catalytically catabolizes the toxic reactive nitrogen intermediates. |
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Term
| A slight review of pathology but what do you see histologically in TB? |
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Definition
| Multinucleated giant cells/Langhans cells |
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Term
| In TB, the granuloma formation is a Type IV hypersensitivity reaction. Describe the cytokines responsible for this action. |
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Definition
Macrophages present antigen to T cells which activate them
T cells then secrete TNF, IL-2, and IFN-gamma.
IL-2 activates other T cells
IFN-gamma activates Macrophages to transform into epitheliod cells
Note that the T-cells also try to simulate Ab production but the bacilli are protected because they are intracellular. |
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Term
| What is it called when macrophages are carried to regional lymph nodes causing subsequent enlargement. |
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Definition
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Term
| Name as many unique virulance factors as you can for M. tuberculosis. |
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Definition
1. Special cell entry methods
2. Can grow intracellularly
3. Interferes with phagocytosis
4. Slow generation time
5. Waxy cell wall
6. Chord Factor |
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Term
| Describe how M. tuberculosis enters macrophages. |
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Definition
TB binds DIRECTLY to mannose receptors with mannosylated glycolipid and LAM.
Complement or Fc receptors bind INDIRECTLY |
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Term
| This particular virulance factor of TB make it resistant to antimicrobacterials, pH changes, and lysosomal destruction. |
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Definition
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Term
| This is a virulance factor of TB which is a unique mycolic acid that can inhibit PMN migration and induce granuloma formation. |
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Definition
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Term
| Clinically one would actually induce a Type IV hypersensitivity reaction to determine exposure to TB. What is this test called? |
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Definition
| TB Skin Test aka Mantoux Test aka PPD (purified protein derivative) |
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Term
| What is a major classification difference between M. tuberculosis and M. leprae |
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Definition
TB is a Facultative Intracelluar Organism
M. leprae is an Obligate Intracellular Organism |
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Term
| This OIP grows best at lower temperatures but cannot be cultured and spreads from contact, most likely respiratory. |
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Definition
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Term
Your patient has dry scaly skin with decreased sensation. Histologically you find lymphocytes and granulomas but very few bacilli. A leproman skin test yields a positive result.
What is the SPECIFIC disease? |
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Definition
M. leprae, Tuberculoid Form
Recall that this has a ROBUST Th1 response so many macrophages are activated which can clear the bacilli |
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Term
Your patient arrives with papular and nodular lesions. Histologically you find a many bacilli but when you perform a lepromin skin test the result is negative.
What is the SPECIFIC disease your patient has? |
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Definition
M. leprae, Lepromatous form.
Note that when the patient is first in the tuberculoid form they have low infectivity. As the disease progresses to the lepromatous form they become more infective. |
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Term
Name the tissue reactions seen in:
TB
Leprosy
Syphillis
Cat Scratch Disease
Sarcoidosis
Chron's Disease |
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Definition
TB: Caseating granuloma
Leprosy: Non-caseating granuloma with bacilli in macrophages
Syphillis: Gumma
Cat Scratch Disease: rounded/stellate granuloma
Sarcoidosis: Non-casiating wtih activated macrophages
Chron's Disease: occasional non-caseating granuloma |
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