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Liz's Mycology Course > Yeast-Like Fungi (YLF) > Flashcards

Yeast-Like Fungi (YLF) Flashcards

(42 cards)

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1
Q

List various lab methods for identifying yeast isolates

A
  • Size and morphology
  • Germ tube
  • Fermentation (anaerobic)
  • Assimilation (aerobic)
  • Morphology on special media (e.g., pseudohyphae on cornmeal)
  • CHROMagar
  • Urease production
  • India ink
  • Latex agglutination
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2
Q

Name the test

- 2-3 hour incubation in rabbit plasma

A

Germ tube

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3
Q

Principle of CHROMagar

A

Chromogenic (color-producing) substrates; used to ID Candida spp

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4
Q

Fermentation test

A
  • Requires GAS PRODUCTION

- Tubes w/ single CHO (“purple broth sugars”) w/ Durham tube and oil on the surface

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5
Q

Fermentation test

- Pos/Neg result

A
  • Pos: acid production and gas production

- Neg: either no acid or gas production OR acid production but no gas production

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6
Q

Assimilation test

A

CHOs utilized as sole carbon source

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7
Q

Describe Candida albicans morphology on cornmeal agar

A

Pseudohyphae and chlamydoconidia (not always present)

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8
Q

Describe Candida tropicalis morphology on cornmeal agar

A

Pseudohyphae

  • Straight, long, graceful
  • “Starburst”
  • Blastoconidia along side of pseudohyphae
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9
Q

Describe Candida krusei morphology on cornmeal agar

A

Elongated blastoconidia (logs on a stream)

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10
Q

Describe Candida parapsilosis morphology on cornmeal agar

A

Pseudohyphae

- Crooked, tangled appearance

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11
Q

Describe Geotrichum morphology on cornmeal agar

A

Arthroconidia present

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12
Q

Describe Trichosporan morphology on cornmeal agar

A

Oval arthroconidia present

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13
Q

List the yeast that DO NOT produce pseudohyphae on cornmeal agar

A
  • Cryptococcus
  • Candida glabrata
  • Rhodotorula
  • Saccharomyces
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14
Q

Which yeast are urease positive?

A
  • Cryptococcus (all species)
  • Trichosporon
  • Rhodotorula
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15
Q

Which yeast are melanin on birdseed agar?

A

Cryptococcus neoformans

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16
Q

Which yeast are germ tube positive?

A

Candida albicans/dubliniensis

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17
Q

Which yeast are stained by India ink?

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A

Cryptococcus spp

18
Q

Which yeast are trehalose positive?

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A

Candida glabrata

19
Q

Which yeast are ascospore stain positive?

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A

Saccharomyces

20
Q

Is CHROMagar a “rapid” test?

21
Q

Is the germ tube test a “rapid” test?

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A

YES! Incubates for 2-3 hours!

22
Q

Is the assimilation test a “rapid” test?

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A

NO (needs to incubate 48-72 hours)

23
Q

Which yeast is #1 at causing human infection?

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A

Candida albicans

24
Q

Which yeast should be associated w/ aggressive infections and treatment failures due to resistance?

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A

Candida glabrata

25
Candida krusei has ____ colonies on SAB
Dry
26
Rhodotorula is what color pigment?
Red/red-orange
27
Cryptococcus are ____ (if it's encapsulated)
Mucoid
28
Candida albicans causes what diseases?
- Yeast infection - Can be involved w/ any part of the body (septicemia, UTI, vaginitis, oral thrush, etc.) - Normal flora of GI tract, vagina, and often skin
29
Candida glabrata causes what diseases?
Diabetic urinary infections
30
Cryptoccocus causes what diseases?
Pulmonary and CNS infections (meningitis) | - C. neoformans is a major pathogen in AIDS patients
31
malassezia spp cause what diseases?
Systemic infections | - Associated w/ hyperalimentation (TPN) (lipids)
32
Trichosporon causes what diseases?
"White piedra" → mat of mycelia around body hair; disseminated disease
33
Cryptococcus neoformans | - Typical sources of infection
Associated w/ soil contamination w/ pigeon, turkey, or chicken droppings (inhalation)
34
Cryptococcus neoformans | - Significance of isolation
Should always be considered significant until proven otherwise
35
Cryptococcus neoformans | - Patient populations at increased risk
AIDS patients
36
Cryptococcus neoformans | - Virulence factors
- Adherence to mucosa | - Resistance to phagocytosis
37
Typical morphology of Cryptococcus spp
- Mucoid colonies (if encapsulated) | - Yeast cells appear larger, irregularly sized
38
Sensitivities of latex agglutination vs. India ink preps for identifying C. neoformans
Latex agglutination is more sensitive than India ink
39
Special culture requirements for Malassezia spp
Requires fatty acids (virgin olive oil) for growth
40
Which yeast has a "spaghetti and meatball" morphology and fluoresces w/ infected skin lesions
Malassezia furfur
41
Which species of yeast produce arthroconidia?
- Trichosporon | - Geotrichum
42
List the pathogenic yeasts
- Candida - Cryptococcus - Trichosporon - Geotrichum - Rhodotorula - Malassezia - Yeast form of dimorphic

Liz's Mycology Course (8 decks)

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