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Flashcards in mycobacteria Deck (30):
1

3 main myco. classes

1. M. tuberculosis complex
2. M. avium complex
3. M. leprae complex

2

2 main TB classes

M. tuberculosis and bovis

3

features of myco.

1. mycolic acids in cell wall
2. aerobic
3. non-spore forming
4. non-motile
5. need many to visualize with microscope

4

what is acid fast bacilli dye

fluorochrome dye to detect more easily

5

how do they stain on gram stain

don't stain

6

steps for kinyoun stain

1. heat fix slide
2. flood with kinyoun dye
3. rinse
4. decolorize with acid
5. rinse
6. dye with methylene blue

7

what is growth rate of Mtb

20 hours - slow

8

3 methods to find Mtb

1. culture - gold standard
2. nucleic acid amplification - targets ribosomal RNA or DNA
3. drug susceptibility testing - important for guided therapy

9

habitats of myco

Mtb and leprae - humans
NTM - watery habitats

10

where is most Tb in canada from

immigrants
aboriginal

11

how is TB aquired

inhalation of droplet nuclei

12

when is Tb transmissable

when smear is positive and active

13

what doe M.bovis cause

infection of GI or tonsils

14

4 factors affecting transmission

1. susceptibility of person - immunocomromise
2. infectiousness of person with TB
3. env.
4. exposure

15

pathogenisis of TB

1. inhalation
2. 1ry focus in middle and lower lung
3. macrophages ingest
4. infected macro bring to regional lymph nodes
5. spread throughout body in blood - 2ry focus
6. initially uninhibited growth until walled off 3-9 weeks

16

what percent become active right away

5% -the rest latent

17

what percent of latent become active

10% over lifetime, or 10% year in HIV

18

steps of reactivate

1. organisms proliferate in well aerated bronchi
2. spread to other sites in lungs
3. become infectious droplet nuclei

19

what is most important immune function for control of TB

AB - very little
cell mediated - major factor

20

what is mechanism of cell mediated response

1. APC present TB to lymphocyte
2. Th1 cytokines
3. Th1 cells activate macrophages via - IL-2, IFN, IL-12
4. macrophage production of IL-1 , TNFa give fever, night sweats, weight loss
-- IL-10 may supress response and cause disease progression

21

what happens in skin test

1. proteins put in
2. read for induration
3. induration due to cell mediated response

22

what is skin test best for

detect latent disease - 75-90% sens

23

what is interferon gamma release assay

in vitro T cells are given Mtb antigen and tested via ELIZA for IFN production

24

what is mgmt of TB

DOT using 2 or more drugs for 6-9 months

25

what is vaccine in TB

does not prevent infection, but prevents progression to clinical disease

26

what is tranmisson of leprosy

likely airborne - not contact

27

what is pathogenisis of leprosy

infects and multiplies in macrophages - escapes phagocytotic killing with surface phenolic glycolipid

28

2 presentations of leprosy and immune type

tuberculoid - Th1
lepromatous - Th2

29

features of tuberculoid

red blothcy lesions, local anasthesia
- DTH reaction to lepromin
- self limiting

30

features of lepromatous

- little or no DTH
- large number of lesions
- skin and nerves involved

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