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Microbiology > Mycobacteria > Flashcards

Mycobacteria Flashcards

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Biology 101 flashcards
1
Q

What is the main acid-fast genus of bacteria?

A

Mycobacteria

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2
Q

What is the gram stain of mycobacteria?

A

gram +

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3
Q

What is the O2 requirements of mycobacteria?

A

Obligate aerobe

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4
Q

Koch identified ________ as cause of TB in 1882:•Humans are reservoir•airborne transmission (as few as 10 cells can result in infection)

A

Mycobacterium tuberculosis

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5
Q

Koch identified Mycobacterium tuberculosis as cause of TB in 1882:• ______ are reservoir
•airborne transmission (as few as 10 cells can result in infection)

A

Humans

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6
Q

Koch identified Mycobacterium tuberculosis as cause of TB in 1882:
• Humans are reservoir
•______ transmission (as few as 10 cells can result in infection)

A

airborne

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7
Q

Mycolic acids in cell wall
Gram+weak staining: use acid-fast stain or specific fluorescent detection
Facultative intracellular growth(in macrophages)
Obligate aerobe (growth in lung macrophages)

A

Mycobacteria

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8
Q

What stain is used to distinguish mycobacteria

A

Acid fast stain

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9
Q

What is the chemical composition of the cord factor within the mycobacterial cell wall?

A

glyco-lipid

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10
Q

Slow, cord-like growth
strongly correlates
with virulence.

Cord-like growth results from adherence of cell surface lipid mycolic acids and glyco-lipids

A

virulence factors of mycobacteria

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11
Q

While many “virulence factors” are listed, their virulence results from the challenge that they provide to the _____ _____ (typically DTH: CD4+ T-cells + macrophages)
because (in most cases) the disease is caused by the immune response, NOT by the mycobacteria.

A

immune response

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12
Q

Facultative intracellular growth in alveolar and other macrophages:
inhibition of phago-lysosome fusion

A

virulence factor of M.tuberculosis and M.leprae

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13
Q

_______ _______ is a “life-long” pathogen: once infected, you may be asymptomatic but never cured.

A

Mycobacterium tuberculosis

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14
Q

the _____ area of the necrosis is where the ______ have been destroyed.

A

central

nuclei

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15
Q

Effective CMI is capable of localizing and stopping infection by M.tuberculosis. Chronic TB is
typical.

What is the exception????

A

Exception: young children under 5 years have a high risk for developing progressive TB due
to insufficient immune system development/activation.

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16
Q
  • 91% no disease
  • 6% clinical TB (2% pulmonary + 3% extrathoracic + 1% both)
  • 3% progressive systemic disease and death.
A

OUTCOMES of untreated primary TB [results for non-immune-compromised patents]:

17
Q

However, ______ (‘open’) TB [also known as “secondary tuberculosis” or in older terms
“galloping consumption” caused by “endogenous reactivation” of prior infection

  • while rare (life-time risk is assessed as <12% for carriers, or less) it is VERY contagious!
    Isolation of acute TB cases is mandatory. Endogenous reactivation is stimulated by stress, malnutrition and HIV
A

acute

18
Q

T/f: concerning Mycobacterium tuberculosis, the “disease” (except for the infection risk of “Open TB”) arises from tissue destruction
by our immune defenses and not by damage caused by the bacterial infection.

A

true

19
Q

t/f: The repeated attempts to remove foci of infection by lung macrophages cause the granulomatous
lung tissue that impairs lung function.

A

true

20
Q

t/f: Breathing impairment in TB is not due to tuberculosis bacilli but by the macrophage-induced tissue
destruction

A

true

21
Q

A positive tuberculin test to subdermal PPD (processed protein derivative of the cell wall of the opportunistic intracellular pathogen M ycobacterial tuberculosis).

A

Mantoux Reaction

22
Q

with the Mantoux Reaction test, a >10mm redness indicates _______ while a >20 mm redness indicates ______.

A

positive test

strong positive

23
Q

Exposure to living attenuated mycobacterium, known as Bacille Calmette-Guérin (BCG), a derivative of M.bovis (which may be identical to M.tuberculosis based on whole genome sequencing):

  • little virulence in humans (but infectious in immune-compromised persons)
  • some protective immunity (when given to young children)
  • BCG vaccination is discouraged in USA because it gives a positive tuberculin test, thus removing an important diagnostic screening tool. (And M.bovis causes disease in immune-compromised persons.)
A

m. tuberculosis vaccine

24
Q

macrophages kill nerves; macules and plaques without sensation

Good prognosis for recovery NOT infectious

A

Th1-response

25
Q

Bad prognosis for recovery Highly infectious

Loss of CMI (CTL lysis and loss of tissue including nerves)

A

Th 2-response

26
Q

Dapsone + rifampin + clofazimine

Rising resistance is becoming a problem.

A

Multi-drug therapy

27
Q

virulence factor of ____ ____

ability to survive and live in lung macrophages

A

m. Tuberculosis

28
Q

clinical factor of ____ _____:

pulmonary and extrapulmonary tuberculosis.

A

m. Tuberculosis

29
Q

treatment of _____ ____:

multidrug therapy (6-12 months)

A

m. Tuberculosis

30
Q

epidemiology of ____ ____:

aerosol (person to person)
all ages
highest risk if : immune compromised (HIV)

A

m. Tuberculosis

31
Q

virulence factor of ____ ____

ability to survive and live in macrophages

A

M. Leprae

32
Q

clinical factor of ____ _____:

tuberculoid to lepramatous leprosy

A

M. Leprae

33
Q

treatment of _____ ____:

multidrug therapy (2 years)

A

M. Leprae

34
Q

epidemiology of ____ ____:

close physical contact

A

M. Leprae

35
Q

t/f: All pathogenic mycobacterial species have (very) slow growth rates

A

true

36
Q

Gram+ (poor staining)

• mycolic acid in cell wall: “partially acid-fast”
(Test to distinguish Nocardia from fungal look-alikes)

Opportunistic pathogen
in immuno-compromised patients

A

nocardia

Microbiology (46 decks)

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