Mycology Flashcards

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1
Q

What is mycology

A

Study of fungi

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2
Q

What is mycoses

A

Fungal infection

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3
Q

Example of mycotoxin

A

aflatoxin of Aspergillus flavus

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4
Q

What kind of organisms are fungi

A

heterotrophic eukaryotes

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5
Q

What are fungi morphologically divided into

A

yeast (single-celled) and filamentous (mold) forms.

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6
Q

What kind of organisms are fungi ( feeding wise)

A

Sacrophytic

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7
Q

Difference between fungal membrane and human membrane

A

Fungal cell contain ergosterol, while mammalian cells contain cholesterol.

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8
Q

What exposes human to a likelihood of infection if they’re immunosuppressed, or if the fungal burden is large

A

Inhaling spores or small yeast cells

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9
Q

How many fungal species are said to be in existence, and how many account for human infections?

A

5 million species, are said to be in existent and approximately 300 infecting humans

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10
Q

What is the fungal cell wall made up of?

A

chitin, mannan and both alpha- and β-glucans.

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11
Q

Size of fungi

A

4 um——-10um

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12
Q

What is the site of action of antifungal drugs, amphtericin B & azole group

A

Ergosterol

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13
Q

What are the he main fungal pathogens responsible for the majority cases of serious fungal disease.

A

•Aspergillus,
•Candida,
•Cryptococcus species,
•Pneumocystis jirovecii,
•endemic dimorphic fungi such as Histoplasma capsulatum and Talaromyces marneffei

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14
Q

Which fungal infections are always lethal unless diagnosed and treated early and correctly.

A

• Cryptococcal meningitis,
•pneumocystis pneumonia, and
•disseminated histoplasmosis

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15
Q

What types of organisms are fungi
In terms of obligatory and facultative

A

Most fungi are obligatory aerobes, some are facultative anaerobes, but none are obligatory anaerobes.

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16
Q

What’s the natural habitat of fungi

A

Natural habitat is the environment except for Candida spp which is part normal flora of humans

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17
Q

What are Common immunosuppression that predispose to mycoses

A

Cancers, cancer treatments, stem cell and solid organ transplant , HIV/AIDS, long term steroid use

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18
Q

What are the types of fungi according to morphology

A

Filamentous fungi (molds)
Yeasts
Yeast-like fungi
Dimorphic fungi

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19
Q

What is the basic morphological feature of filamentous fungi

A

long branching filaments or hyphae, which intertwine to produce a mass of filaments or mycelium

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20
Q

Describe the colonies of filamentous fungi

A

Colonies are strongly adherent to the medium and unlike most bacterial colonies cannot be emulsified in water

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21
Q

What are the types of hyphae

A

septate or non septate

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22
Q

Describe the filamentous fungal colonies

A

strongly adherent to the medium and unlike most bacterial colonies cannot be emulsified in water

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23
Q

What aid the diagnostics of filamentous fungi

A

Their colony on agar aids their diagnosis by their appearance and pigments produced

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24
Q

How do yeasts reproduce

A

formation of buds known as blastospores

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25
Q

Describe the yeast colonies

A

Yeasts colonies resemble bacterial colonies in appearance and in consistency (can me emulsified by water?)

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26
Q

Describe yeast

A

These occur in the form of round or oval bodies which reproduce by the formation of buds known as blastospores. They are also called budding yeast, with daughter cells attached

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27
Q

What are dimorphic fungi

A

Molds in the environment (saprophytic phase) 25-27C
Yeast in the body (parasitic phase) 37C

They are fungi that can exist in the form of both mold[1] and yeast. This is usually brought about by change in temperature

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28
Q

What’s the difference between yeast and molds

A

Yeast are unicellular and reproduce by budding
Molds are multicellular and reproduce by spore formation

29
Q

Examples of dimorphic fungi

A

Histoplasma carpsulatum, Blastomyces dermatitidis
Coccidioidis immidis

30
Q

What are the types of mycoses (fungal infection)

A

•Superficial
•Subcutaneous
•Systemic
•Opportunistic

31
Q

Examples of subcutenous fungal infections

A

• Sporothrix schenkii (Sporotrichosis)
• Mycetoma
•Chromomycosis

32
Q

Biological tests for fungi

A

Germ tube test
Urease test
Sporulation test
Water bait test

33
Q

What test differentiates candida and cryptococci

A

Urease test

34
Q

Function of water bait test

A

To identify phytophthora and pythium in water

35
Q

What are the different agar cultures used to grow fungi

A

Brain heart infusion medium
Malt extract agar
Sabouraud’s dextrose agar

36
Q

What is chitin

A

A polysaccharide composed of long chains of N-acetylglucosamine.

37
Q

What other polysaccharides other than chitin are present in the fungal cell

A

β-glucan, a long polymer of D-glucose.

38
Q

In what form do fungus exist

A

Most fungi exist saprophytically (depending on dead organic matter), while some others are parasitic (depending of living organisms)

39
Q

Examples of filamentous ( mold like ) fungi

A

Mucor,
Rhizopus

40
Q

Examples of yeast like fungi

A

Saccharomyces cerevisiae

41
Q

I’m what form of fungi is mycelium seen

A

Molds (Filamentous fungi)

42
Q

How does mycelium grow

A

grows by branching and tip elongation.

43
Q

What are the two forms of hyphens in molds

A

Septate and non septate

44
Q

What helps with the diagnosis of molds

A

Their colony on agar aids their diagnosis by their appearance and pigments produced

45
Q

What for yeast colonies resemble

A

Yeasts colonies resemble bacterial colonies in appearance and in consistency

46
Q

•what s the principal means by which fungi reproduce

A

Sporulation

47
Q

What are the two forms of aporulation

A

Sexual and asexual sporulation

48
Q

What is asexual sporulation

A

Asexual spores (conidia) are formed by mitosis in or on specialized hyphae (conidiophores)

49
Q

Why can conidia become air borne

A

Because they are easily detached from their underlying mycelia, conidia can become airborne and, therefore, are a major source of fungal infection

50
Q

4 examples of conidia

A

Arthrospores, which arise by fragmentation of the ends of hyphae and are the mode of transmission of Coccidioides immitis;
•Chlamydospores, which are rounded, thick-walled, and quite resistant
Blastospores, which are formed by the budding process (some yeasts, e.g., C. Albicans, can form multiple buds that do not detach, thus producing sausagelike chains called pseudohyphae, which can be used for identification)
•Sporangiospores, which are formed within a sac (sporangium) on a stalk by molds such as Rhizopus and Mucor

51
Q

What is sexual sporulation

A

Some fungi reproduce sexually by mating and forming sexual spores (e.g., zygospores, ascospores, and basidiospores).

52
Q

What’s a zygospore

A

Zygospores are single large spores with thick walls;

53
Q

What are ascospores

A

ascospores are formed in a sac called ascus,

54
Q

What are basidiospores

A

basidiospores are formed externally on the tip of a pedestal called a basidium.

55
Q

Examples of sexual spores

A

zygospores,
ascospores, and
basidiospores

56
Q

What are the lab identification of fungi

A

•Direct microscopic examination,
•Culture of the organism
•DNA probe tests
•Serologic Tests

57
Q

What does direct examination of fungi depend on

A

•It depends on finding characteristic asexual spores, hyphae, or yeasts in the light microscope

58
Q

How is the fungal specimen prepped for a direct examination

A

The specimen is either treated with 10% potassium hydroxide (KOH) to dissolve tissue material, leaving the alkali-resistant fungi intact, or stained with special fungal stains.

59
Q

What agar is fungi cultured on

A

Sabouraud’s agar,

60
Q

How does Sabouraud’s agar work in the culture of fungi

A

It facilitates the appearance of the slow-growing fungi by inhibiting the growth of bacteria in the specimen
•The appearance of the mycelium and the nature of the asexual spores are frequently sufficient to identify the organism

61
Q

what is cutenous fungal infection also called

A

dermatophytoses

62
Q

What are dermatophytes

A

The cause cutenous fungal infection
They fall into three genera, each with many species: Trichophyton, Epidermophyton, and Microsporum

63
Q

What are the three genera of dermatophytes

A

Trichophyton,
Epidermophyton, and
Microsporum

64
Q

What are subcutaneous fungal infections

A

Subcutaneous mycoses are fungal infections of the dermis, subcutaneous tissue, and bone. Examples are Sporotrichosis

65
Q

What kind of people do fungi infect

A

immunicompromised

66
Q

Examples of systemic mycoses

A

Coccidioidomycosis, Histoplasmosis, and Blastomycosis

67
Q

What are opportunistic mycoses

A

Opportunistic mycoses afflict debilitated or immunocompromised individuals but are rare in healthy individual

68
Q

Examples of opportunistic mycoses

A

Candidiasis and cryptococcosis.