Mycology Flashcards

1
Q

What are saprophytes?

A

Eating dead matter

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2
Q

What are the three ways in which fungi can adversely affect us?

A
  1. allergens
  2. Toxin producers
  3. infectious agents
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3
Q

Does the development of fungal allergies require colonization?

A

no

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4
Q

What are mycotoxins?

A

Toxins produced by fungi

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5
Q

What are ergot alkaloids?

A

Fugal mycotoxin that produces hallucinations

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6
Q

What are alfaltoxins?

A

Hepatotoxins from fungus that grows on peanuts

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7
Q

What is stachybotrys?

A

A mycotoxin produced by household mold. Brain effects

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8
Q

What are the two typical targets of antifungal therapies?

A

Fungal cell wall

Membrane sterol composition (ergosterol)

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9
Q

What is the lipid component of fungal membranes that is analgous to cholesterol, and serves as a target for antifungal therapy?

A

Ergosterol

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10
Q

Will abx that affect bacterial cell walls have any effects on fungal cell walls?

A

No

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11
Q

What are the three major components of the fungal cell wall?

A

Mannan
Glucan
Chitin

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12
Q

Are fungal cells wall very or poorly immunogenic?

A

Very

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13
Q

Is the capsule that some fungi produce immunogenic?

A

Yes

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14
Q

What are the two categories of fungi?

A

Yeast

Molds

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15
Q

What is the term that describes fungi that can transition from a yeast form to a mold form?

A

Dimorphic

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16
Q

How many cells do yeast have? What shape are they?

A

Unicellular spheres or ellipsoids

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17
Q

How do yeasts reproduce?

A

Budding

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18
Q

A germ tube is diagnostic for what fungi?

A

Candida albicans

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19
Q

What are the small buds that are produced from the process of budding?

A

Blastoconidia

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20
Q

What are pseudohyphae?

A

Long extensions of fungi “chains of buds that never broke off”

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21
Q

What are hyphae?

A

a long, branching filamentous structure of a fungus. In most fungi, hyphae are the main mode of vegetative growth.

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22
Q

What is a mass of hyphae?

A

Mycelium

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23
Q

Molds that are infectious (and dimorphic) grow in what form: yeast or mold?

A

Yeast

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24
Q

Reproductive fungi units produced Asexually are known as what?

A

Conida

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25
Q

Reproductive fungi units produced sexually are known as what?

A

Spores

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26
Q

Where on existing molds do conidia form?

A

along hyphae or on stalk like structures known as conidiophores.

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27
Q

What are the two forms of hyphae, that are distinguished by the presence/absence of cell walls?

A

Spetate/aseptate hyphae

28
Q

What are the three different forms of conidia?

A

Macro
Micro
Arthro

29
Q

What are arthrocanidia?

A

Spores that form in the center of a hyphae

30
Q

What is the main diagnostic procedure for identifying fungi?

A

Visually

31
Q

Conidia which form within a hyphal element are known as what?

A

chlamydoconidia or arthroconidia.

32
Q

What are superficial mycoses?

A

Infections of the outermost layer of the skin/hair

33
Q

What are cutaneous mycoses?

A

infection which extends deep into the epidermis as well as invasive hair and nail infections.

34
Q

What are subcutaneous mycosis?

A

infections involving the dermis, subcutaneous tissues, muscle, and fascia.

35
Q

What are systemic mycoses?

A

infections that originate primarily in the lung but may spread to any organ in the body.

36
Q

What are opportunistic mycoses?

A

infection associated primarily with immunosuppressed individuals.

37
Q

What is characteristic of fungi that can cause systemic mycoses?

A

Are dimorphic

38
Q

Intact skin, pH, competition with normal bacterial flora, epithelial turnover rate, desiccated nature of the stratum corenum, and mucous membranes are all examples of what type of immunity?

A

Innate

39
Q

What role do antibodies play in our immune response to fungi?

A

Antibodies are sometimes produced, but there is little evidence for a role of humoral immunity in resistance or resolution of infection.

40
Q

What is the main immune defense against fungi?

A

Neutrophils

41
Q

The severity of a disease caused by fungi is dependent on what factors? (4)

A

Size of innoculation

magnitude of tissue destruction

ability of fungi to multiply in tissue

Immuologic status of host

42
Q

What do macrophages have to do in order to get rid of persistent fungi?

A

Become activated by IFN-gamma

43
Q

When is topical therapy indicated for a fungal infection?

A

When the infection is superficial or cutaneous

44
Q

When is systemic therapy of antifungals indicated?

A

When the fungi are at the subcutaneous level or beyond

45
Q

What is the origin of systemic fungal infections?

A

Inhalation

46
Q

What are the four examples of systemic mycoses given in class?

A
Histoplasmosis
Blastomycosis
Paracoccidiodomycosis
Coccidioidmycosis
Cryptococcosis
47
Q

What are the major targets of antifungal drugs? (5)

A
Cell wall synthesis
Cell membrane
Inhibit protein syn
Inhibit nucleic acid syn
Disrupt microtubules
48
Q

What are the antifungal targets in the cell wall of a fungus?

A

Glucan/chitin synthesis

49
Q

What is the class of drugs that directly target the cell membrane of a fungus? How do these work?

A

Polyenes–binding to fungal-specific membrane sterols (ergosterol)

50
Q

What are the classes of drugs that inhibits ergosterol synthesis?

A

Azoles
allylamines
thiocarbamates
Morpholines

51
Q

What is the class of antifungals that inhibit both RNA and DNA synthesis? What is the scope of fungi that these drugs target?

A

Nucleoside analogs (like 5-fluorocytosine!)

Target yeasts (little effect on dimorphic fungi)

52
Q

What are allyalmines effective in killing? Ineffective?

A

Effective against dermatophytes

Ineffective against yeast

53
Q

What is the MOA of echinocandins?

A

Inhibit the synthesis of beta-glucans, an important component of the fungal cell wall.

54
Q

What is KI used to treat? How does it work?

A

Subcutaneous infections caused by sporothrix schencki

55
Q

What is the class of drugs that inhibits cell wall synthesis?

A

Echinocandins

56
Q

What is the MOA of grisans?

A

Inhibits microtubule assembly

57
Q

What type of drug is amphotericin B? What is the MOA?

A

Polyene, binds to ergosterol and causes pore fomation

58
Q

What is the KOH prep used in the lab to identify fungal infections?

A

Add KOH to tissue scrapings–will dissolve skin tissue at a faster rate than the fungus, and thus allows for visual identification

59
Q

All fungi are gram (positive or negative)?

A

Positive

60
Q

What is the black stain used in the lab that specifically stains chitin?

A

Chlorazol black

61
Q

What is the whtie stain used in the lab that specifically fungal cell walls?

A

Calcofluor white

62
Q

The india ink stain is used to identify what fungus? What is the target here?

A

Cryptococcus neoformans–stain targets the capsule

63
Q

What is the germ tube test diagnostic of?

A

Candida albicans

64
Q

If an india ink test is positive, what is the infectious agent?

A

Cryptococcus neoformans

65
Q

What is the commonly used agar in culturing fungi?

A

Sabouraud dextrose agar

66
Q

What are the major differences in culturing fungi as compared with bacteria?

A

Reduced temp
DIfferent pH
Longer time