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Micro 425 > Exam 4 (Mycobacteria spp.) > Flashcards

Exam 4 (Mycobacteria spp.) Flashcards

1
Q

Mycobacteria are acid fast due to:

A

High lipid content

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2
Q

Mycobacteria are Gram___ non-spore forming, slender, slow-growing___, obligate ___:

A

Gram+/variable
bacilli
obligate aerobes

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3
Q

Mycobacteria are divided into these two groups:

A

1) Mycobacterium tuberculosis complex

2) Non-tuberculosis mycobacteria (NTM)

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4
Q

T/F

All Mycobacterium tuberculosis complex are slow growers and produce non-pigmented colonies:

A

True

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5
Q

List the 8 species within the Mycobacterium tuberculosis complex:q

A 
M. tuberculosis
M.  bovis
M. bovis BCG
M. africanum
M. caprae
M. canettii
M. microti
M. pinnipedii
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6
Q

Which species/strain of Mycobacterium tuberculosis complex has been used in live vaccines for over 70 years, and has led to infection in some patients:

A

M. bovis BCG

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7
Q

There are over ___ species of NTM, and some transiently colonize __, __, and ___ of healthy humans:

A

130 species

skin, GI, resp tract

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8
Q

Do NTM species typically spread person to person:

A

No.

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9
Q

What is the classification of NTM:

A

Runyon groups (I- IV)

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10
Q

This is an older classification system of NTM based on growth rate, colony morphology and pigment production (caratenoids):

A

Runyon groups

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11
Q

Photochromogens belong to Runyon Group___:

A

Group I

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12
Q

Scotochromogens belong to Runyon group___:

A

Group II

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13
Q

_____produce pigment in dark or light conditions and belong to Runyon group___:

A

Scotochromogens

Group II

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14
Q

____are non-pigmented regardless of incubation in dark or light conditions, and belong to Runyon Group___:

A

Non-photochromogens

Group III

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15
Q

____take fewer than 7 days to appear on solid media and belong to Runyon group__:

A

Rapid Growers

Group IV

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16
Q

Runyon Group IV:

A

Rapid Growers

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17
Q

Runyon Group III:

A

Non-photochromogens

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18
Q

List the 3 Mycobacteria species that are photochromogens (group I):

A

M. kansasii
M. marinum
M. asiaticum

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19
Q

List the 4 Mycobacteria species that are scotochromogens (group II):

A

M. scrofulaceum
M. szulgai
M. gordonae

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20
Q

This non-photochromogen is found in hot water taps in hospitals, and causes pulmonary infections and disseminated disease:

A

M. xenopi

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21
Q

This scotochromogen can cause cervical adenitis in children:

A

M. scrofulaceum

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22
Q

Why are M. avium and M. intracellulare reported in combination, as a complex:

A

On clinical grounds and routine lab methods, they cannot be distinguished from each other

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23
Q

Mycobacterium avium complex (MAC) is an important pathogen in ____ patients:

A

AIDS

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24
Q

Does pulmonary disease in AIDS patients present with granulomas or tissue death?

A

No.

Patients exhibit increased mucus production, can provide stress on bronchioles and lead to bronchiectasis.

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25
Q

Is MAC spread person to person?

A

No.

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26
Q

List the two Mycobacterium species in the Runyon group IV:

A

M. fortuitum

M. chelonae

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27
Q

What will Runyon group IV species grow on that most other Mycobacteria spp will not:

A

MacConkey (w/out crystal violet)

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28
Q

_____ and ____ from Runyon group ___ are the only 2 species that will grow in 5 days on MacConkey at 37 degrees C:

A

M. fortuitum

M. chelonae

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29
Q

This is a non-cultivatable nontuberculous mycobacterium, has not been grown in vitro because it is an obligate intracellular bacteria that only survives several minutes in the environment….is found in armadillos and mice:

A

M. leprae

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30
Q

Why can’t M. leprae be grown in vitro:

A

It is an obligate intracellular bacteria.

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31
Q

___ causes leprosy and is found in ___ and ___:

A

M. leprae

armadillos and mice

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32
Q

T/F

TB is increasing worldwide, and disease progression is becoming more rapid.

A

True.

There is a need for rapid isolation/identification.

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33
Q

What is the most important factor with growth of Runyon group IV species on MacConkey:

A

Most important factor is presence of growth in 5 days. Color change is not of great significance.

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34
Q

Describe a proper sputum specimen for Mycobacteria testing:

A

Sputum taken early morning for 3 consecutive days

**children with TB typically cannot cough up sputum

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35
Q

List some specimens for Mycobacteria spp testing:

A

Virtually any tissue or organ

  • sputum
  • tissue/granuloma
  • urine
  • bone, csf, blood, GI, stool
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36
Q

T/F

Specimens from sterile sites can be directly plated to media:

A

True

blood, urine, CSF

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37
Q

Processing of sputum specimens for acid fast bacteria requires ____/____ followed by ____ and ____ via centrifugation. These steps kill normal flora and also release TB bacteria from cells/mucin:

A

digestion/decontamination

neutralization and concentration

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38
Q

___: liquefy mucus with mucolytic agents which releases the bacteria from the mucin:

A

Digestion

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39
Q

Decontamination eliminates this:

A

mixed bacterial flora

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40
Q

What makes Mycobacterium resistant to decontamination:

A

High lipid cell wall

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41
Q

_____ with phosphate buffer or H20 is done following the 15 minute digestion/decontamination step:

A

Neutralization

42
Q

What is used for digestion of mycobacterium:

A

NaOH

43
Q

In the NALC NaOH method of sputum digestion/decontamination, NaOH is ____ when mixed with _____:

A

NaOH is reduced to 2% when mixed with NALC

44
Q

____ is the preferred method for sputum digestion/decontamination and requires ____ minute incubation:

A

NALC NaOH

15

45
Q

NALC is a ____ agent, releasing bacteria, while NaOH is both a ____ and ____ agent:

A

NALC: mucolytic
NaOH: mucolytic/decontaminating agent

46
Q

What is done following the digestion/decontamination step:

A

add the phosphate buffer followed by 15 mins of centrifugation

47
Q

What stain would be done to mucous specimen:

A

acid fast

after digestion, etc

48
Q

What BSL___ lab is used to identify TB, and/or identify all Mycobacteria spp. and perform susceptibility testing:

A

BSL 3

49
Q

BSL3 BSC and centrifuge room should have ______ walls and work surfaces, ____ air flow, and ____filters vented to outside:

A

non-permeable
directional
HEPA

50
Q

What must be done with protective clothing after working in a BSL3:

A

removed/autoclaved

51
Q

High ____cell content of Mycobacteria binds _____ and resists ____ by acid-alcohol:

A

Lipid
Fuchsin dye
decolorization

52
Q

List the two methods of acid fast staining:

A
  • Ziehl-Nelson (hot)

* Kinyoun (cold)

53
Q

This acid fast staining method uses a higher concentration of phenol in the primary stain to accelerate the staining process and thus does not require heat:

A

Kinyoun (cold)

54
Q

Fluorochrome stain is used for Mycobacteria spp. because they have an ____ for ____:

A

affinity for fluorochrome

55
Q

You need to scan at least ____ oil immersion fields before you report a slide as _____:

A

300

negative

56
Q

300 oil immersion fields is equivalent to ___ (400x) fields on on a fluorochrome slide:

A

30

57
Q

For optimal recovery of Mycobacteria spp., you should use at least one _____ and one ____:

A

one solid media

one liquid medium

58
Q

List the two liquid media used for Mycobacteria spp:

A

BACTEC 128 medium

Middlebrook 7H9 Broth

59
Q

What two solid media should be used for Mycobacteria spp:

A
  • one with agar base (Middebrook 7H10)

* one with egg-potato base (Lowenstein-Jensen, or Petragnani)

60
Q

Both Lowenstein-Jensen and Petragnani media contain malachite green for this purpose:

A

Malachite green dye inhibits other microbes (contaminants)

61
Q

How is tube media incubated for Mycobacteria spp:

A

35 C, dark, 5-10% CO2, humid

*tube initially in slanted position w/ cap loose for 1 wk to let fluid evaporate and CO2 enter

62
Q

How often should Mycobacteria spp cultures be examined for growth, and when does growth for most species appear on liquid media, and solid media:

A

examine weekly

liquid: 2 wks
solid: 3-6 weeks

63
Q

___ is often used as a back up if liquid media fails:

A

solid media

64
Q

M. tuberculosis takes and average of ___ to grow and an additional ___ for susceptibility testing:

A

2-4 wks

2-4 wks

65
Q

A new____ technique by Ghodbane is reducing the cultivation time for M. tuberculosis to as little as 72 hours:;

A

incubation

includes microaerophilic conditions

66
Q

What is the immunodiagnostic test for TB and how does it work:

A

T-SPOT TB blood test

Wells contain TB specific antigen and thus detect TB activated T cells from blood samples

67
Q

All Mycobacteria produce ___, some species lack the enzyme necessary to convert __ to ___, resulting in high accumulation of niacin in the culture medium:

A

niacin

niacin—-> niacin ribonucleotide

68
Q

Is the niacin test enough to ID M. tuberculosis:

A

no

69
Q

With the niacin filter paper test, what color will the broth turn if niacin is present (positive):

A

yellow

70
Q

Which two species of Mycobacteria are Niacin+:

A

M. tuberculosis

M. simiae

71
Q

Only two species of Mycobacteria produce nitroreductase, which catalyzes the reaction of nitrate reduction to nitrite:

A

M. tuberculosis

M. kansasii

72
Q

It is very important controls be used for this test, and the M. tuberculosis control has to be strongly positive, otherwise results of unknowns are unreliable:

A

Nitrate reduction test

73
Q

What enzyme reduces nitrate to nitrite, and which two species have the enzyme:

A

nitroreductase
M. tuberculosis
M. kansasii

74
Q

Tween 80 hydrolysis is a ____ trade name, and is ___ to certain organisms:

A

detergent

toxic

75
Q

This test identifies Mycobacteria possessing a lipase that splits the compound into oleic acid and polyoxyehtylated sorbitol:

A

Tween 80 hydrolysis

76
Q

How do you perform a Tween 80 hydrolysis test:

A
  • 2 drops Tween 80 added to 1mL saline and inoculated w/ loopful of organism
  • incubate 35 C for ~12 days
  • Fluid will change from light orange to pink or red if positive
77
Q

What does a positive result look like in Tween 80 hydrolysis:

A

Fluid will change from light orange to pink or red

78
Q

Which species is a quick positive for Tween 80 hydrolysis, and which are typically negative:

A

M. kansasii (positive)

M. tuberculosis complex (negative)

79
Q

T/F

Most Mycobacteria species produce catalase:

A

True

80
Q

T/F

All Mycobacteria species produce a heat stable catalase:

A

False.

*Most M. tuberculosis complex organisms do not produce heat stable catalase.(68 degree catalase neg)

81
Q

____: Broth culture medium/automated continuous growth monitoring systems:

A

BACTEC

82
Q

Positive niacin and nitrate reduction, 68 degree catalase neg, strong acid fast+, rough, dry, buff, non-pigmented on LJ media, slightly curved rods w/ beaded appearance:

A

M. tuberculosis

83
Q

TB+ cultures are typically kept by the lab for ___ following ID for epidemiological purposes:

A

6-12 months

84
Q

List the two conventional methods for M. tuberculosis susceptibility testing:

A
  • Liquid broth automated systems (BACTEC)

* Absolute concentration (provides MIC)

85
Q

Molecular methods for susceptibility testing for M. tuberculosis are testing for the gene/gene mutation that causes ___ resistance:

A

Rifampin

86
Q

T/F

Inhalation of a single bacilli has been shown to lead to infection with Tuberculosis:

A

True

not necessarily disease though

87
Q

Upon exposure to TB, ____% develop disease, ___ remain with latent infection:

A

5-10%

90%

88
Q

T/F

One third of the world’s population is infected with TB:

A

True

latent or active

89
Q

What is it called when person with latent TB has disease manifestation at a later time:

A

Secondary (reactivation) TB

90
Q

Define miliary TB:

A

spread to other organs hematogenously

91
Q

TB bacteria travel from respiratory droplets to alveoli, they are taken up by ___ which are unable to kill them, which leads to eventual formation of ____:

A

macrophages

granulomas

92
Q

List the two clinical screening methods for TB:

A
  • QuantiFERON-TB Gold In-Tube test

* Purified Protein Derivative (PPD)

93
Q

Treatment consists of using ___ drugs in combination for ___ months:

  • Isoniazid
  • Rifampin
  • Pyrazinamide
  • Ethambuterol
A

2-3 drugs
9-12 months

*problems with patient compliance and drug resistance

94
Q

Multidrug resistant TB is resistant to ___ and ____:

A

Isoniazid and Rifampin

95
Q

Studies being done on association of ____ between Johne’s disease in cattle and Crohn’s disease in humans:

A

M. avium, subspecies paratuberculosis

96
Q

M. leprae causes ____ aka ____:

A

leprosy

Hansen’s disease

97
Q

This is a chronic disease of the skin, mucous membranes, nerve tissue, primary reservoir is humans, is usually associated with tropical climates, and is caused by an obligate intracellular bacteria:

A

Leprosy aka Hansen’s disease

M. leprae

98
Q

What’s the significance of Molkai Hawaii:

A

Contact with infected human skin/nasal secretions transmits leprosy

99
Q

Leprosy can be found in this part of the US, and ___serve as a reservoir:

A

SW

armadillos

100
Q

Would a skin biopsy be part of confirming leprosy:

A

Yes

101
Q

Can leprosy be cured:

A

Yes.

Antibiotics such as Clofazimie, Rifampin, Dapsone

Micro 425 (12 decks)

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