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ID Ex 2 > Mycobacterium > Flashcards

Mycobacterium Flashcards

1
Q

How long does it take to grow TB on a plate?

A

3-6 weeks for primary isolation

All are aerobes

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2
Q

Hallmark of TB stain

A

Acid fast staining

- 60% lipid (most are 15%) so it takes up stain easily, but cant get rid of it

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3
Q

Which bacteria results in the most deaths?

A

M.TB

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4
Q

Transmission of TB

A

Aerosol

  • respiratory droplet nuclei
  • small particles capable of reaching alveolus
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5
Q

How many people exposed to TB will result in an infxn?
How of those with a TB infxn will progress to primary disease?
How many of those that contain the TB infxn will result in reactivation?

A

30%
- due to inadequate non-immunologic defense

5% of 30%
- due to inadequate immunologic defense

5% of the 95% that was contained will reactivate
- due to inadequate immunologic defense.

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6
Q

TB replicates in macrophages, where do they get carried to?

A

draining lymp nodes –> blood –> other organs

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7
Q

What confers resistance to INH?

A

Down regulation of katG

*katG (bacterial catalase peroxidase)- normally activates INH

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8
Q

When are individuals who are recently infected, most prone to progressing?

A

1-2 yrs

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9
Q

classic pattern of reactivated (post primary) TB

A

Upper lobes

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10
Q

High risk conditions for TB

A

High risk:

  1. HIV
  2. close contact
  3. recently infected
  4. abnl chest x ray

Intermediate risk:

  1. Transplant or immunosuppression
  2. Medical conditions
  3. Injection drug users
  4. . Recent arrivals from endemic contries
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11
Q

Risk for new infxn

A
  1. Contacts to infxn diseases
  2. Health care workers
  3. Other workers exposed to TB cases
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12
Q

Pulmonary sx of TB

A
  1. COugh >3 weeks
  2. Chest pain
  3. Hemoptysis

Systemic:

  1. Fever
  2. Chills
  3. Night sweats
  4. Appetite loss
  5. Weight loss
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13
Q

diagnostic work up of TB

A
  1. 3x Sputum sample –> AFB (acid fast bacillus) smear
  2. Mycobacterial culture
  3. Species ID
  4. Drug susceptibility testing
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14
Q

What do you suspect if TB is resistant to Rifampin?

A

most likely multi drug resistant TB

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15
Q

Tx of TB

A

4 for 2 months

2 for 4 months

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16
Q

If you have no risk for TB, how many mm does it have to be to be considered positive on PPD?
What about if you are a child?
Immunosuppressed?

A

> 15 mm

Child: >10

Immunosuppressed: 5mm

17
Q

Quantiferon IT

A

3 antigens
Draw 3 tubes of blood
Put an antigen into each tube (- control, + control, Ag)

  • measure serum gamma interferon [ ] if Pos = TB
18
Q

TSPOT TB

A

Use 2 antigens
Stimulate lymphocyte over night and observe plate
- each spot is a lymphocyte producing interferon
8 or more = Pos test

19
Q

What test is best done on BCG vaccinated indiv?

A

Interferon Gamma release assays (IGRAs)

- high specificity

20
Q

Shortest drug regimen for TB

A

Isoniazid and rifapentine

  • longer half life
  • 3 months (not 4 with RIF)
  • less hepatotoxic
21
Q

1 killer of AIDS pts

A

M.Tb

22
Q

Nontuberculous Mycobacteria

A

Exposed to them a lot
Not transmissible fr hu to hu
- VERY resistant to Ab

Most common sx is in the lung

23
Q

Which state has the most NTM ?

A

Hawaii
Cali
Florida

  • hot and humid
  • people moving there already having dz (arizona)
24
Q

Lady wyndamere syndrome

A

Tall, Skinny women more likely to get TB

*named after play: Women may be suppressing their coughs

25
Q

What stain uses the property of the acid fastness of mycobacteria to differentiate it form other bacteria?

A

Ziehl Neelson

26
Q

What type hypersensitivity is TB?

A

Delayed type IV hypersensitivity

- disease manifestations are due to hypersensitivity to tubercular antigens and not the result of bacterial toxin

27
Q

What type of immunity (cellular or humoral or both) plays a role in M. tuberculosis?

A

Cellular only

  • develops at 2-6 weeks, dominated by TH1
  • reactivation is usually due to cellular immune fxn

*humoral immunity has no major role in recovery or protection or diagnostic use.

28
Q

SapM

A

protein produced that cleaves late endosomal vesicular PI3P in the phagosome membrane, which prevents fusion of the phagosome with the lysosome

29
Q

Man-LAM

A

inhibits phagosomal maturation

30
Q

Cathelicidin

A

kills intracellular M. tuberculosis in hu macrophages

31
Q

Does drug resistance for TB come from acquiring foreign DNA that encodes resistance?

A

No.

32
Q

Most accurate way to dz leprosy?

A

bioposy

or

  1. 1/m hypopoigmented skin patches
  2. 1/m thickened peripheral nerves
  3. (+) skin smear

ID Ex 2 (18 decks)

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