mycobacteria

Question 1

3 main myco. classes

Answer 1

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

Question 2

2 main TB classes

Answer 2

M. tuberculosis and bovis

Question 3

features of myco.

Answer 3

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

Question 4

what is acid fast bacilli dye

Answer 4

fluorochrome dye to detect more easily

Question 5

how do they stain on gram stain

Answer 5

don’t stain

Question 6

steps for kinyoun stain

Answer 6

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

Question 7

what is growth rate of Mtb

Answer 7

20 hours - slow

Question 8

3 methods to find Mtb

Answer 8

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

Question 9

habitats of myco

Answer 9

Mtb and leprae - humans

NTM - watery habitats

Question 10

where is most Tb in canada from

Answer 10

immigrants

aboriginal

Question 11

how is TB aquired

Answer 11

inhalation of droplet nuclei

Question 12

when is Tb transmissable

Answer 12

when smear is positive and active

Question 13

what doe M.bovis cause

Answer 13

infection of GI or tonsils

Question 14

4 factors affecting transmission

Answer 14

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

Question 15

pathogenisis of TB

Answer 15

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

Question 16

what percent become active right away

Answer 16

5% -the rest latent

Question 17

what percent of latent become active

Answer 17

10% over lifetime, or 10% year in HIV

Question 18

steps of reactivate

Answer 18

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

Question 19

what is most important immune function for control of TB

Answer 19

AB - very little

cell mediated - major factor

Question 20

what is mechanism of cell mediated response

Answer 20

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

Question 21

what happens in skin test

Answer 21

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

Question 22

what is skin test best for

Answer 22

detect latent disease - 75-90% sens

Question 23

what is interferon gamma release assay

Answer 23

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

Question 24

what is mgmt of TB

Answer 24

DOT using 2 or more drugs for 6-9 months

Question 25

what is vaccine in TB

Answer 25

does not prevent infection, but prevents progression to clinical disease

Question 26

what is tranmisson of leprosy

Answer 26

likely airborne - not contact

Question 27

what is pathogenisis of leprosy

Answer 27

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

Question 28

2 presentations of leprosy and immune type

Answer 28

tuberculoid - Th1

lepromatous - Th2

Question 29

features of tuberculoid

Answer 29

red blothcy lesions, local anasthesia

• DTH reaction to lepromin
• self limiting

Question 30

features of lepromatous

Answer 30

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