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Flashcards in Mycology Deck (66):
1

What are saprophytes?

Eating dead matter

2

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

1. allergens
2. Toxin producers
3. infectious agents

3

Does the development of fungal allergies require colonization?

no

4

What are mycotoxins?

Toxins produced by fungi

5

What are ergot alkaloids?

Fugal mycotoxin that produces hallucinations

6

What are alfaltoxins?

Hepatotoxins from fungus that grows on peanuts

7

What is stachybotrys?

A mycotoxin produced by household mold. Brain effects

8

What are the two typical targets of antifungal therapies?

Fungal cell wall
Membrane sterol composition (ergosterol)

9

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

Ergosterol

10

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

No

11

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

Mannan
Glucan
Chitin

12

Are fungal cells wall very or poorly immunogenic?

Very

13

Is the capsule that some fungi produce immunogenic?

Yes

14

What are the two categories of fungi?

Yeast
Molds

15

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

Dimorphic

16

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

Unicellular spheres or ellipsoids

17

How do yeasts reproduce?

Budding

18

A germ tube is diagnostic for what fungi?

Candida albicans

19

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

Blastoconidia

20

What are pseudohyphae?

Long extensions of fungi "chains of buds that never broke off"

21

What are hyphae?

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

22

What is a mass of hyphae?

Mycelium

23

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

Yeast

24

Reproductive fungi units produced *Asexually* are known as what?

Conida

25

Reproductive fungi units produced *sexually* are known as what?

Spores

26

Where on existing molds do conidia form?

along hyphae or on stalk like structures known as conidiophores.

27

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

Spetate/aseptate hyphae

28

What are the three different forms of conidia?

Macro
Micro
Arthro

29

What are arthrocanidia?

Spores that form in the center of a hyphae

30

What is the main diagnostic procedure for identifying fungi?

Visually

31

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

chlamydoconidia or arthroconidia.

32

What are superficial mycoses?

Infections of the outermost layer of the skin/hair

33

What are cutaneous mycoses?

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

34

What are subcutaneous mycosis?

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

35

What are systemic mycoses?

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

36

What are opportunistic mycoses?

infection associated primarily with immunosuppressed individuals.

37

What is characteristic of fungi that can cause systemic mycoses?

Are dimorphic

38

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?

Innate

39

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

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

40

What is the main immune defense against fungi?

Neutrophils

41

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

Size of innoculation

magnitude of tissue destruction

ability of fungi to multiply in tissue

Immuologic status of host

42

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

Become activated by IFN-gamma

43

When is topical therapy indicated for a fungal infection?

When the infection is superficial or cutaneous

44

When is systemic therapy of antifungals indicated?

When the fungi are at the subcutaneous level or beyond

45

What is the origin of systemic fungal infections?

Inhalation

46

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

Histoplasmosis
Blastomycosis
Paracoccidiodomycosis
Coccidioidmycosis
Cryptococcosis

47

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

Cell wall synthesis
Cell membrane
Inhibit protein syn
Inhibit nucleic acid syn
Disrupt microtubules

48

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

Glucan/chitin synthesis

49

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

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

50

What are the classes of drugs that inhibits ergosterol synthesis?

Azoles
allylamines
thiocarbamates
Morpholines

51

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

Nucleoside analogs (like 5-fluorocytosine!)

Target yeasts (little effect on dimorphic fungi)

52

What are allyalmines effective in killing? Ineffective?

Effective against dermatophytes

Ineffective against yeast

53

What is the MOA of echinocandins?

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

54

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

Subcutaneous infections caused by sporothrix schencki

55

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

Echinocandins

56

What is the MOA of grisans?

Inhibits microtubule assembly

57

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

Polyene, binds to ergosterol and causes pore fomation

58

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

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

59

All fungi are gram (positive or negative)?

Positive

60

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

Chlorazol black

61

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

Calcofluor white

62

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

Cryptococcus neoformans--stain targets the capsule

63

What is the germ tube test diagnostic of?

Candida albicans

64

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

Cryptococcus neoformans

65

What is the commonly used agar in culturing fungi?

Sabouraud dextrose agar

66

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

Reduced temp
DIfferent pH
Longer time