Fungi Flashcards

1
Q

what do fungi have in their plasma membranes instead of cholesterol?

A

ergosterol

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2
Q

what kingdom are fungi from?

A

eukarya

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3
Q

what kind of fuel do fungi need to survive and what term defines that?

A

preformed organic energy supplying compounds, heterotrophic

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4
Q

what type of ribosomes and cell walls do fungi have?

A

chitin and beta glucan cell walls

80S ribosomes

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5
Q

what is a major barrier in antifungal treatment?

A

toxicity- fungi have more similar molecules to humans (few possible targets)

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6
Q

what are some differences in where fungi can live compared to bacteria? What implication does this have on where they grow

A

they can live in more extreme conditions- drier, higher osmotic pressure and colder
Tend to be more cutaneous infections and grow in refrigerated food

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7
Q

what are the two main types of fungi?

A

yeasts and molds

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8
Q

describe the structure of a mold.

A

mats (mycelia) of fibers (hyphae)

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9
Q

describe a yeast

A

a single celled fungus that reproduces by budding

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10
Q

describe the reproduction cycle of a fungus

A

very complicated reproduction pathways involving multiple forms of fungus and possibly different types of reproduction

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11
Q

what structure makes identifying fungi easier microscopically?

A

there are 5 types of asexual spores with distinct appearance. can help aid diagnosis

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12
Q

explain thermal dimorphism and what implications does it have for infection?

A

when a fungus grows at a mold at 24C and as a yeast at 37C- grow as yeasts in the body

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13
Q

what are the two hallmark immune responses to fungal infection?

A

granulomas and suppurative exudate (pus)

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14
Q

how are fungal pathogens transmitted and what implications does it have on treatment?

A

grow in the environment and cannot be passed from person to person
means there is little drug resistance but also infections cannot be eradicated

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15
Q

what type of yeast is normal flora?

A

C albicans

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16
Q

what is mycotoxicosis?

A

syndrome caused by eating fungal toxins (not a fungal infection)

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17
Q

what type of hypersensitivity response is common with fungal infections?

A

type 1 (allergies)

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18
Q

what skin test is used to diagnose fungal infection?

A

PPD type test

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19
Q

why is KOH added to fungal microscopy samples?

A

to kill all human cells

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20
Q

what medium is fungus cultured on?

A

Sabouraud’s agar

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21
Q

if a patient has a dangerous systemic fungal infection, what is the quickest way to diagnose it?

A

PCR amplification and molecular testing

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22
Q

What tests are used for systemic fungal infections?

A

PCR and serology

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23
Q

what are the major classes of antifungal agents?

A

polyenes, azoles and echinocandins

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24
Q

what is the mechanism of a polyene drug and what is the major type?

A

disrupt cell membrane at ergosterol insertion sites

Amphotericin B

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25
Q

what is the mechanism of azoles?

A

to inhibit ergosterol synthesis

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26
Q

what is the mechanism of echinocandins?

A

inhibits beta- glucan synthesis

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27
Q

what is the most effective broad spectrum antifungal class?

A

polyenes

28
Q

why is amphotericin B only used in life threatening fungal infections?

A

it is nephrotoxic

29
Q

what antifungal is approved for use on pregnant women with systemic fungal infection?

A

Amphotericin B

30
Q

what are the two major Azoles and what fungi are they effective against?

A

Diflucan and Fluconazole

candidiasis and cryptococcosis

31
Q

what is the major benefit of Echinocandins?

A

low toxicity

32
Q

what fungal infections are Echinocandins effective against?

A

candida and aspergillus

33
Q

which types of mycoses do not require thermal dimorphism?

A

superficial mycoses

34
Q

what are the symptoms of superficial mycoses?

A

minor symptoms of itch and discoloration

35
Q

what is used to treat superficial mycoses?

A

topical azoles or oral griseofulvin

treat all sites simultaneously

36
Q

what is fungal infection of the skin called and which structures does it infect?

A

dermatophytosis

infects skin, hair and nails (keratinized structures)

37
Q

what are the symptomes of dermatophytosis called and where are the major subtypes commonly called?

A

Tinea

jock itch, athlete’s foot and ringworm

38
Q

how are tineas transferred?

A

fomite or autoinnoculation

39
Q

how are dermatophytoses diagnosed?

A

KOH microscopy mount and culture

40
Q

how is a subcutaneous mycosis contracted?

A

trauma exposing subcutaneous tissue to the environment (usually thorn pricks and splinters)

41
Q

how do subcutaneous mycoses spread?

A

through the lymphatics towards the trunk

42
Q

what is a common complaint that patients will have with subcutaneous mycoses?

A

ineffective treatment with antibiotics

43
Q

how are subcutaneous mycoses treated?

A

oral azoles

serious cases- amphotericin B and local surgery

44
Q

what is sporotrichosis and what organism is it caused by?

A

it is a subcutaneous mycosis caused by sporothrix spp

45
Q

in what two cases can Sporotrichosis become a pulmonary infection?

A

if the patient has COPD or has been treated long term with corticosteroids

46
Q

what is a potential consequence of sporotrichosis infection with an immunosuppressed patient?

A

dissemination and meningitis

47
Q

how is sporothrix spp diagnosed?

A

biopsy and culture at room temp from pus

48
Q

how does one contract a systemic fungal infection?

A

inhaling spores (not person-person transmissible)

49
Q

what is the range of severity for a systemic mycosis?

A

asymptomatic clearance to death

50
Q

a systemic mycosis may mimic what type of infection? How are they differentiated in terms of exposure

A

TB

exposed to american dirt, not foreign crowds

51
Q

what is coccidioides and where is it endemic?

A

a thermally dimorphic fungus that can cause systemic infection. endemic to US southwest and latin america

52
Q

how does coccidioides grow in the following types of weather and when is it transmitted to people?
Wet and Dry

A

Wet weather-grows mold

Dry weather- mold dries and arthrospores are released (infectious)

53
Q

60% of coccidioides infections results in what?

A

asymptomatic or flulike clearance by innate immunity or containment by CMI

54
Q

what are the two diseases caused by mild infection by coccidioides and what are they characterized by?

A

valley fever and desert rheumatism

pulmonary infection and erythema nodosum

55
Q

what characterizes a severe coccidioides infection?

A

major pneumonia or dissemination in blood or by marophages

56
Q

what are the risk factors for severe coccidioides?

A

old age, black or phillipino, late in pregnancy, immunocompromised and occupational exposure

57
Q

when is coccidioides infection treated and how?

A

if predisposed to complications- oral azoles
meningitis- fluconazole
pregnant or disseminated- amphotericin B

58
Q

the severity and disease caused by an opportunistic mycosis is majorly due to what factor?

A

the patient’s pre existing conditions

59
Q

optimal treatment of an opportunistic infection does what?

A

treats the infection and the underlying condition

60
Q

cryptococcus causes what type of infection?

A

opportunistic mycosis

61
Q

what host characteristic allows an infection of cryptococcus?

A

reduced CMI

62
Q

what routine bloodwork finding is characteristic of cryptococcosis?

A

normal results with no inflammatory markers

63
Q

when do patients typically present for a cryptococcosis infection?

A

late in disease with meningitis and skin nodules or pulmonary symptoms

64
Q

how is cryptococcosis diagnosed?

A

biopsy, CSF or crag (serotyping)

65
Q

how is cryptococcosis treated?

A

a combination of azole and amphotericin B while treating the underlying condition