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Concepts in medical science > Exam 3: Mycobacteria > Flashcards

Exam 3: Mycobacteria Flashcards

1
Q

Mycobacteria species are weakly

A

gram positive

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2
Q

what type of laboratory method is needed to see mycobacteria?

A

acid-fast

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3
Q

acid-fast organisms appear ____ against a ____ background

A

red; blue

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4
Q

mycobacteria species are strict

A

aerobes

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5
Q

mycobacteria species produce

A

catalase

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6
Q

t/f mycobacteria species have capsules, spores, and toxins

A

false

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7
Q

t/f mycobacteria species grow very slowly in culture and usually require an enriched culture

A

true

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8
Q

what are mycobacteria species cell walls composed of

A

peptidoglycan layer similar to other gram +, mycolic acids (long chain fatty acids), lipid polysaccharide complex functionally similar to LPS layer of gram -

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9
Q

mycobacterium tuberculosis is what type of pathogen

A

facultative intracellular pathogen

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10
Q

The captain of death

A

mycobaterium tuberculosis

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11
Q

virulence factor of mycobacteria species

A

mycolic acids + LPC layer form a WAXY COAT

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12
Q

waxy coat is

A

hydophobic, hardy, impenetrable, resistant to dry, common disinfectants and acids

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13
Q

MTB allows itself to be engulfed by

A

alveolar macrophages but then can block the destruction of the phagosome that it is hiding in

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14
Q

white plague

A

mycobacterium tuberculosis

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15
Q

1 infectious disease worldwise

A

mycobacterium tuberculosis

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16
Q

who accounts for 50% of mycobacterium tuberculosis cases in the U.S. today?

A

immigrants

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17
Q

mycobacterium tuberculosis is transmitted primarily by

A

airbone respiratory droplets

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18
Q

usually requires crowded, indoor conditions with repeated exposure

A

mycobacterium tuberculosis

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19
Q

rate of infectivity is high, but rate of disease is low

A

mycobacterium tuberculosis (only 5% of infected people develop active/clinical disease)

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20
Q

where must mycobacterium tuberculosis (bacilli) make it after being inhaled to cause infection?

A

alveoli

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21
Q

When bacilli reach alveoli and are phagocytosed by alveolar macrophages, these three possible outcomes can occur:

A
  1. immediate clearance of the organism
  2. primary disease
  3. latent infection
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22
Q

primary disease TB

A

IMMEDIATE ONSET of active disease

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23
Q

symptoms of primary disease TB

A

hemoptysis, night sweats, weight loss, lymphadenopathy, unintentional weight loss, fatigue

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24
Q

which of the three possible outcomes is most common?

A

latent infection

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25
Q

multiples within the alveolar macrophages and remains contained inside for long periods –> travels inside the macrophages to infect other organs

A

primary TB

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26
Q

as the bacteria (in primary TB) multiply in the lungs, the macrophages can release cytoines –>

A

attract T cells and other inflammatory cells to the site

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27
Q

granulomas occur with which TB

A

primary TB

28
Q

granuloma

A

inflammatory cells are fused together – multinucleated giant cell that surround the bacilli

29
Q

as granuloma grows, center becomes necrotic and is called ______, bc of the cheesy, semisolid character of the material at the center

A

caseous necrosis

30
Q

most of the clinical manifestations of primary TB results from

A

damage caused by the host response, not the bacilli themselves

31
Q

typical host of primary TB

A

50 y.o. man who just immigrated to the U.S.

32
Q

immune response “wins” and stops the growth and multiplication of MTB inside macrophages –> some organisms enter an INACTIVE, DORMANT STATE

A

latent TB

33
Q

reactivation TB only occurs in

A

10% of cases (not common)

34
Q

when someone gets primary TB when they are younger and then the disease reactivates years later when they are immunocompromised

A

reactivation TB

35
Q

reactivation TB thought to be due to

A

waning immunity

36
Q

where is the most common reactivation site for reactivation TB due to aerobic/favorable environment

A

apex of lungs

37
Q

during initial infection or upon reactivation, bacilli can DISSEMINATE to regional lymph nodes, kidneys, bones, genital tract, bowel, brain/meninges

A

extrapulmonary TB

38
Q

where extrapulmonary TB is most serious

A

TB meningitis

39
Q

dx gold standard for mycobacterium TB

A

sputum culture for mycobacteria with AFB smear

40
Q

what might someone see on a chest xray of someone with TB?

A

ghon complex (when granuloma centers get necrotic so they eat their way through the bronchiole and calcify)

41
Q

Tuberculin skin testing aka

A

PPD/Mantoux test

42
Q

what does the PPD test identify?

A

latent TB in asymptomatic patients with possible history of exposure

43
Q

PPD

A

purified protein derivative (is a tuberculin protein)

44
Q

tuberculin protein that gets injected is an antibody or antigen?

A

antigen

45
Q

PPD results read how many hours after injection?

A

48-72

46
Q

positive result PPD

A

individual has been infected with MTB at some point – does NOT discriminate between active and inactive disease

47
Q

negative result PPD

A

no contact or infection (also may be - in immunocompromised patient who is unable to react to the antigen)

48
Q

CI to PPD test

A

history of BCG vaccine (may cause a systemic reaction or severe ulceration and necrosis at the test site)

49
Q

BCG

A

Bacille Calmette Guerin

50
Q

when and where is the BCG vaccine usually given?

A

newborns in areas of the world where TB prevalance is high

51
Q

BCG vaccine contains live strains of

A

M. bovis

52
Q

True/falase, mycobacterium leprae cannot grow on artificial media or tissue culture bc it is an obligate intracellular parasite

A

true

53
Q

cannot reproduce outside their host cell

A

obligate intracellular parasite

54
Q

how long is the incubation period for mycobacterium leprae?

A

7 years

55
Q

leprosy aka

A

Hansen’s bacillus or Hansen’s disease

56
Q

virulence factor of mycobacterium leprae

A

waxy coat (mycolic acids + LPC layer)

57
Q

naturally infects aramadillos

A

mycobacterium leprae

58
Q

a chronic disease that begins in the skin and mucous membranes –> progresses int onerves

A

Hansen’s disease/leprosy

59
Q

infectivity is low; must have prolonged close contact

A

mycobacterium leprae

60
Q

mycobacterium leprae is spread through

A

direct inoculation and droplet inhalation

61
Q

2 forms of mycobacterium leprae

A

tuberculoid

lepromatous

62
Q

tuberculoid mycobacterium leprae

A

causes development of macules or plauqes of face, trunk, and extremities –> bacteria invade peripheral nerves –> thickens nerve sheaths and causes loss of sensation

63
Q

small number of organisms present in lesions; not as contagious

A

tuberculoid (mycobacterium leprae)

64
Q

causes a deeply nodular, diffuse, extensive infection that causes severe disfigurement of the face and extremeties; can lead to loss of nasal bones and digits

A

lepromatous (mycobacterium leprae)

65
Q

M. leprae grows in

A

cooler regions of the body (nose & ears esp.)

Concepts in medical science (7 decks)

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