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Hannah's Intersystem > Fungi > Flashcards

Fungi Flashcards

1
Q

Are fungi eukaryotic or prokaryotic? What is 1 main difference between fungi and plants?

A

Eukaryotic

Do not have chlorophyll

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2
Q

What is S. cerevisiae?

A

Brewer’s/baker’s yeast

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3
Q

What are the 3 classifications of fungi?

A

Unicellular (yeasts)
Filamentous (moulds)
Dimorphic

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4
Q

What is the metabolic classification of unicellular fungi?

A

Facultative anaerobes

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5
Q

How do unicellular fungi reproduce?

A

Asexually by budding

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6
Q

How do unicellular fungi appear on agar?

A

Produce colonies

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7
Q

What is the metabolic classification of filamentous fungi?

A

Aerobes

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8
Q

How do filamentous fungi reproduce?

A

By conidia (asexual spores)

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9
Q

How do filamentous fungi appear on agar?

A

Produce mycelia

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10
Q

What are dimorphic fungi?

A

Can switch between unicellular and filamentous forms

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11
Q

How big is the average yeast?

A

2-3um

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12
Q

Are fungi saprophytes?

A

Mostly

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13
Q

Give an example of a filamentous fungi

A

Penicillium

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14
Q

How does filamentous fungi appear under the microscope?

A

Hyphae and conidia

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15
Q

List the different types of fungi in order from most to least virulent

A 
Dimorphic fungi
Dermatophytes
Agents of subcutaneous mycoses
Opportunists
Toxic fungi
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16
Q

Give an example of a dimorphic fungus and the disease it causes

A

Histoplasma capsulatum

Causes “cave’s disease”

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17
Q

Which of the fungis are primary pathogens?

A

Dimorphic fungi

Dermatophytes

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18
Q

What makes dimorphic fungi good pathogens?

A

Can grow as filamentous fungi in environment, yeasts in body

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19
Q

List 3 genera of dermatophytes

A

Microsporum
Trichophyton
Epidermophyton

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20
Q

What type of fungi cause ringworm?

A

Dermatophytes

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21
Q

Where do dermatophytes grow?

A

In keratin tissues (e.g. skin, hair, nails)

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22
Q

How do dermatophytes cause symptoms? Which dermatophytes are more likely to cause symptoms than others?

A 
Release metabolic by-products which can cause symptoms
Zoophilic dermatophytes (e.g. Microsporum canis) more likely to cause symptoms than anthropophilic (e.g. Trichophyton rubrum) dermatophytes
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23
Q

What type of fungus causes tinea?

A

Dermatophytes

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24
Q

Are agents of subcutaneous mycoses generally pathogenic? How are humans innoculated with these organisms?

A

Low grade pathogens

Innoculated directly onto the skin

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25
Q

What is tinea corporis?

A

Tinea of the body

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26
Q

Give 3 examples of subcutaneous mycoses

A

Mycetoma
Chromoblastomycosis
Phaeohyphomycosis

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27
Q

What are bacterial mycetomas called?

A

Acintomycetoma

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28
Q

What is tinea cruris?

A

Tinea of the groin

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29
Q

What are fungal mycetomas called?

A

Eumycetoma

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30
Q

What is the proper name of mycetoma?

A

Maduromycosis

31
Q

Give an example of an opportunistic mycoses

A

Candidiasis (caused by Candida albicans)

32
Q

What is the most common acintomycetoma?

A

Nocardia spp.

33
Q

What is the most common eumycetoma?

A

Madurella spp.

34
Q

What are the 3 different types of candidiasis?

A

Mucocutaneous
Chronic mucocutaneous (in those who can’t clear pathogen)
Systemic

35
Q

Give 2 examples of agents responsible for cryptococcosis. Which of these are opportunistic?

A

C. neoformans

C. gattii (not necessarily opportunistic)

36
Q

What are 1 of the defining features of a mycetoma?

A

Sulphur granules

37
Q

What diseases are caused by cryptococcosis?

A 
Pulmonary infection (usually mild)
Meningitis (in immunocompromised, unless C. gattii)
38
Q

Give an example of a toxic fungi

A

Aspergillus

39
Q

List 3 presentations of aspergillosis

A

Saprophytic (fungus ball)
Allergic
Systemic

40
Q

When does systemic candidiasis usually occur? What happens with a systemic infection?

A 
With immunodeficiency (e.g. in neonates or HIV patients)
Causes sepsis, can be fatal
41
Q

What is pseudohyphae?

A

Hyphae without septa

42
Q

Give an example of an organism that produce pseudohyphae

A

C. albicans

43
Q

Give an example of a fungal AIDS-defining illness

A

Cryptococcal (fungal) meningitis

44
Q

Does cryptococcus have a capsule?

A

Yes

45
Q

What type of fungi is aspergillus?

A

Filamentous

46
Q

What type of fungi is cryptococcus?

A

Yeast

47
Q

What type of fungi is candida?

A

Yeast

48
Q

How are fungal infections diagnosed?

A 
Microscopy
Culture
Ag detection
PCR (pan-fungal if not sure if fungal infection)
Other (e.g. mass spectrometry)
49
Q

List 4 systemic drugs used in anti-fungal chemotherapy. Give an example of each

A

Polyenes (e.g. amphotericin B)
Triazoles (e.g. fluconazole, voriconazole)
Echinocandins (e.g. capsofungin)
5-fluorocytosine

50
Q

How can fungi be distinguished?

A

By conidia (have to grow under special conditions)

51
Q

What is an India ink stain?

A

Negative stain

52
Q

How can skin be viewed with microscopy?

A

Normally opaque under microscope; keratin must be dissolved

53
Q

What is the characteristic microscopic feature of epidermophyton?

A

Distinctive appearance of macroconidia

54
Q

What is the “quick and dirty” test for C. albicans?

A

Germ tubes; make pseudohyphae in the lab (usually in horse serum)

55
Q

What diagnostic method is often used for cryptococcus?

A

Ag detection (detect capsular Ag in CSF, can be used to monitor treatment)

56
Q

What is the drawback of amphotericin B?

A

Very toxic

57
Q

List 2 classes of topical anti-fungal chemotherapeutic agents and give examples of each

A

Polyenes (e.g. nystatin)

Imidazoles (e.g. clotrimazole)

58
Q

What are the 2 main targets of anti-fungals?

A

Ergosterol

Nucleic acids

59
Q

What is ergosterol?

A

Sterol found specifically in fungal cytoplasmic membranes

60
Q

What do polyenes act on?

A

Bind to ergosterol to disrupt integrity of fungal cell membrane

61
Q

What is the mechanism of action of allylamines, triazoles and morpholines?

A

Affect synthesis of ergosterol

62
Q

Why are polyenes so toxic?

A

Also bind to cholesterol and disrupt host cell membranes

63
Q

How are polyenes usually administered?

A

IV

64
Q

What is the mechanism of action of 5-flurocytosine?

A

Prodrug that is metabolised to 5-flurouracil in the body

Affects DNA and RNA synthesis

65
Q

How is 5-flurocytosine selectively for fungi?

A

Only fungi have cytosine deaminase to activate the drug

66
Q

What is the drawback of 5-flurocytosine?

A

Resistance occurs readily

67
Q

What drug is usually used to treat Candida spp.?

A

Fluconazole

68
Q

What drugs are usually used to treat cryptococcus?

A

Amphotericin B + 5-flurocytosine

69
Q

What drug is usually used to treat Aspergillus?

A

Voriconazole

70
Q

What drug is usually used to treat dimorphic fungi?

A

Amphotericin B

71
Q

What topical agents are usually used to treat dermatophytes?

A

Terbinafine (“Lamisil)
Clotrimazole (“Canesten”)
Amorolfine (“Loceryl”

72
Q

What orally administered agents are usually used to treat dermatophytes?

A

Terbinafine
Fluconazole
Griseofulvin (most toxic)

73
Q

When are orally administered agents used to treat dermatophytes?

A

When infection is difficult to treat topically or is widely disseminated on the skin
Also if in nails (grows slowly, have to treat topically for a long time - oral treatment may be preferred to somewhat reduce treatment time)

Hannah's Intersystem (16 decks)

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