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MYCV > LEC3 - General Methods for Examination of Fungi > Flashcards

LEC3 - General Methods for Examination of Fungi Flashcards

1
Q

fungi Incubation is at

A

22°C-30°C

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2
Q
  • If suspected for dimorphic fungus, cultures should also be incubated
    at what temperature
A

37 * C

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3
Q

fungi cultures are maintained for how many weeks

A

4-6 weeks

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4
Q

Record the ff upon culturing;

A

✓Number of days required to see fruiting structures
✓Mold or yeast
✓Media used
✓Temperature
✓Morphology of colonies

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5
Q

texture of colonies

A

velvety
cottony
powdery
hairy

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6
Q

what are the things to consider in Colony Morphology

A
  1. Texture
  2. Growth Measurements
  3. Center and Margin of Culture
  4. Sulcation
  5. Exudates
  6. Reverse Colony
  7. Any soluble pigments
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7
Q
  • General medium
  • Most commonly use
A

Sabouraud Dextrose Agar (SDA)

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8
Q

Sabouraud Dextrose Agar (SDA)

____% dextrose and an acidic pH

A

4%

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9
Q

pH of Sabouraud Dextrose Agar (SD

A

acidic

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10
Q

Sabouraud Dextrose Agar (SDA)

A

❖ Chloramphenicol
❖ Gentamicin
❖ Cycloheximide

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11
Q

Sabouraud Dextrose Agar (SDA)

modifications

A
  • Emmon’s Modification
  • Mycosel Agar
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12
Q

Sabouraud Dextrose Agar (SDA)
Modifications:

  • Emmon’s Modification

describe the dextrose percentage and ph

A

2% DEXTROSE in neutral pH

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13
Q

Sabouraud Dextrose Agar (SDA)
Modifications:

Mycosel Agar

describe what is modified

A

SDA + Chloramphenicol and Cycloheximide

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14
Q
  • Enrichment agar
A

Brain Heart Infusion (BHI) Agar

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15
Q

Brain Heart Infusion (BHI) Agar is used in

A

Recovery of Cryptococcus neoformans and dimorphic transitions of
Sporothrix schenckii and Paracoccidioides brasilliensis

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16
Q

Brain Heart Infusion (BHI) Agar are can be in what type of agar

A

tube or plates

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17
Q

Brain Heart Infusion (BHI) Agar

modifications

A
  • BHI Broth + Penicillin
  • BHI + Gentamicin + Chloramphenicol
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18
Q

Brain Heart Infusion (BHI) Agar

modifications :

BHI Broth + Penicillin

what is being isolated

A

growth of Zygomy

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19
Q

Brain Heart Infusion (BHI) Agar

modifications :

BHI + Gentamicin + Chloramphenicol

what is being isolated

A

Cryptococcus neoformans from
contaminated specimens

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20
Q
  • Enriched selective medium
A

Inhibitory Mold Agar

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21
Q

Inhibitory Mold Agar
contains what substances

A

inorganic salts, chloramphenicol and gentamicin

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22
Q
  • Primary recovery of pathogenic fungi
A

Inhibitory Mold Agar

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23
Q
  • General purpose medium
A

Sabouraud Dextrose + BHI (SABHI)

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24
Q
  • Addition of blood increases isolation of dimorphic fungi
A

Sabouraud Dextrose + BHI (SABHI)

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25
Q

Promotes conversion to the yeast stage

A

Sabouraud Dextrose + BHI (SABHI)

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26
Q
  • Enhance growth of dermatophytes in cutaneous specimens and
    inhibit other fungi and bacteria
A

Dermatophyte Test Medium

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27
Q

Dermatophyte Test Medium inhibitors

A
  • Cycloheximide, Chloramphenicol and Gentamicin
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28
Q

Selective and differential for presumptive identification of genus
Candida from primary plates

A

CHROMagar Candida

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29
Q

isolation of Candida albicans specifically for the
growth of Chlamydospores

A

Cornmeal Tween 80 Agar

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30
Q

Cornmeal Tween 80 Agar

Addition of ____ to provide contrasting
background for observing morphologic features
of yeast

A

trypan blue

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31
Q

Christensen’s Urea Agar composition

A

Composed of 2% Urea, Phenol

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32
Q

Christensen’s Urea Agar is used in the isolation of

A

Cryptococcus, Trichosporon and Rhodotorula sp

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33
Q

agar used in * Differential identification of
Aspergillus spp

A

Czapek’s Agar

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34
Q

Czapek’s Agar components

A

Sodium nitrate, sucrose and yeast
extract

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35
Q

medium used for * Identification of Cryptococcus
neoformans

A

Niger Seed Agar/Birdseed Agar/Staib’s
Medium

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36
Q

Niger Seed Agar/Birdseed Agar/Staib’s
Medium composition

A

Potassium nitrate, peptone, meal
extract, sulfanilic acid, N,N-dimethyl1naphthylamine

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37
Q

Enhances pigmentation and sporulation of
dermatophytes

A

Potato Dextrose Agar

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38
Q

Potato Dextrose Agar composition

A

Potato extract, D-glucose

39
Q

used in Differentiation of Microsporum canis (yellow pigment) to Microsporum auduinii (rice
grains turn brown)

A

Rice Medium

40
Q

rice medium composition

A

White rice extract, polysorbate 80

41
Q

medium used for Detection of Cryptococcus spp, differentiation of Trichophyton
mentagrophytes from Trichophyton rubrum

A

Urea Agar

42
Q

component of urea agar

A

Peptone, dextrose, sodium chloride,
monopotassium phosphate, urea and
phenol red

43
Q

positive result of urea agar

A

Pink

44
Q

used for the Conversion of mold to yeast form of Blastomyces dermatitidis

A

Cottonseed Agar

45
Q

Indirect Microscopic Examination through
Culture

things needed to observe

A
  • Septate versus sparsely septate hyphae
  • Hyaline or phaeoid hyphae
  • Fruiting structures
  • Type size, shape and arrangement of conidia
46
Q
  • Microscopic characteristics that should be observed:
A
  • Septate/Aseptate
  • Hyaline/Phaeiod
  • Fruiting Structures
  • Types, size, shape and arrangement of conidia
47
Q

Methods for microscopic examination

A
  • LPCB Tease Preparation (acto-phenol cotton blue)
  • Scotch Tape/Adhesive/Cellophane Preparation
  • Riddell/Microculture Technique
48
Q

LPCB (Lactophenol Cotton Blue) Tease Mount
* Teasing needles are used to remove a portion of the mycelium from
the ____of the colony

A

middle third

49
Q

Disadvantage of LPCB (Lactophenol Cotton Blue) Tease Mount

A

disruption of conidia during the teasing process

50
Q
  • gently touching a piece of clear tape, sticky side down, to the surface
    of the colony and then removing it.
A

Cellophane Tape/Scotch Tape Preparation

51
Q

The tape is placed onto a drop of LPCB on a slide and examined

A

Cellophane Tape/Scotch Tape Preparation

52
Q

Advantage of Cellophane Tape/Scotch Tape Preparation

A

retention of conidial arrangement

53
Q

Disadvantage of Cellophane Tape/Scotch Tape Preparation

A

potential contamination of the colony, should be read within 30 minutes and then discarded

54
Q

Useful for demonstrating the natural morphology of fungal structure

A

Slide Culture Technique/Riddell Technique

55
Q

Direct Microscopic Examination perks

A
  • Directly from clinical specimen
  • Rapid report to the physician
  • Provides clue to the genus of the organism
  • Might provide evidence of infection despite negative cultures
56
Q
  • Most common routine test
A

10-20% Potassium Hydroxide (KOH) Test

57
Q

10-20% Potassium Hydroxide (KOH) Test sample sources

A

Nail scrapings, hair, skin scales, thin slices of tissue

58
Q
  • Presumptive test for fungal infections
A

10-20% Potassium Hydroxide (KOH) Test

59
Q

Upon collection of sample, 10-20% KOH is added to the slide, wait for
__, then look for yeast or hyphae.

A

15-30 minutes

60
Q

-rapid breakdown of cellular debris
without the need for heating

A

DMSO (Dimethyl sulfoxide)

61
Q

Uses a fluorescence dye

A

KOH with Calcofluor White Stain

62
Q

KOH with Calcofluor White Stain

In need of a ____ microscope to
visualize formation of yeast and hypha

A

fluorescence

63
Q

Superior to KOH test

A

KOH with Calcofluor White Stain

64
Q

india Ink/Nigrosin Stain

what sample is needed

A

csf sample

65
Q

India Ink/Nigrosin Stain
* CSF sample is used to examine presence of ___

A

Cryptococcus neoformans

66
Q

In india ink/nigrosin ink, what is the appearance of yeast

A

Yeast surrounded by a halo (capsule) against a black background.

67
Q

periodic acid schiff color of fungal element

A

magenta in pink or green background

68
Q

gomori methenamine silver color of fungal element

A

black in green background

69
Q

giemsa color of fungal element

A

purple blue yeast with clear halo or capsule in pink-purple background

70
Q

india ink color of fungal element

A

yeast with clear halo in black background

71
Q

KOH color of fungal element

A

REFRACTILE

72
Q

KOH - cakcofluor white

A

fluorescent

73
Q

masson-fontana color of fungal element

A

brown in pink-purple background

74
Q

Sterile 5- to 10-mm hair fragments are floated on sterile water
supplemented with a few drops of sterile 10% yeast extract

A

Hair Perforation T

75
Q

Differentiate T. mentagrophytes from T. rubrum -

5-day ____test at
room temperature

A

Urease Test

76
Q

urease test uses what agar

A

Christensen urea agar

77
Q

Single most useful nutritional test for dermatophytes

A

Thiamine Requirement

78
Q

Only ____ are identified to be
germ tube positive

A

Candida albicans and Candida dubliniensis

79
Q

7 different ____ number 1 through 7 are
used to determine the nutritional requirements of the
Trichophyton spp

A

Trichophyton agars

80
Q

can
be used as an alternative in Germ Tube Production

A

Brain Heart Infusion Broth, Trypticase Soy Broth, Nutrient Broth

81
Q

Germ Tube Production

  • Incubated at 37°C and must be read not beyond_
A

3 hrs

82
Q

Assimilation tests identify which carbohydrates a yeast can use
aerobically as a sole carbon source

A

Carbohydrate Assimilation

83
Q

Serological Test

A
  • Use of blood samples
  • Complement Fixation
  • Agglutination
84
Q
  • Complement Fixation
A
  • Histoplasma capsulatum
  • Coccidioides immitis
  • Blastomyces dermati
85
Q

Agglutination

A

Cryptococcus neoformans
* Other dimorphic fungi

86
Q

Molecular Detection

A
  • PCR
  • Use the DNA of fungi as a confirmatory in identification
87
Q

Positive for Urease

A
  • Cryptococcus and Rhodotorula
  • Most strains of Trichosporon spp
88
Q

Negative for Urease test

A
  • Candida spp
89
Q

Temperature Studies of Cryptococcus spp

*

A

Weak growth at 35°C, no growth at 42°C, optimal growth at 25°C

90
Q

Temperature Studies of * Candida sp

A
  • Most can grow up to 45°C
  • Candida dubliniensis cannot grow at 45°
91
Q

Potassium Nitrate Assimilation
*___ (positive control)

A

Cryptococcus albidus

92
Q

Potassium Nitrate Assimilation

__ (negative control)

A

Candida albicans

93
Q

accurate method to determine the ability of yeast to use nitrate as
the sole source of nitrogen

A

Potassium Nitrate Assimilation

94
Q

Potassium Nitrate Assimilation

Positive test result turns the medium __, if negative it turns ;__

A

blue; yellow

MYCV (10 decks)

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