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BM211 microbiology > Block C 2 > Flashcards

Block C 2 Flashcards

fungal diseases

1
Q

what is mycosis (plural mycoses)

A

any infection caused by a fungus/growth of fungus on or in the body

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2
Q

what does it mean for pathogenic fungi to be dimorphic

A

exists as either yeasts or in filamentous form

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3
Q

what are the 3 major mechanisms that fungi cause disease through

A

-inappropriate immune responses
-toxins (mycotoxins)
-host infection (mycoses)

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4
Q

what is the most common toxin that aspergillus produces

A

aflatoxin

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5
Q

what is aflatoxin in relation to birds

A

carcinogenic

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6
Q

what human diseases does aflatoxin cause

A

cirrhosis (children are more prone)
asthma

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7
Q

where does superficial mycosis infect

A

only the surface layer of skin, hair, or nails

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8
Q

how is superficial mycosis treated

A

topical antifungal creams
liquid aerosols

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9
Q

name of the drugs that treat superficial mycosis

A

miconazole nitrate
griseofulvin

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10
Q

collective name of fungi that cause superficial mycoses

A

dermatophytes

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11
Q

what is superficial mycoses caused by

A

trichophyton spp.

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12
Q

transmission of superficial mycosis

A

spores
itching and flaking skin

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13
Q

what is subcutaneous mycosis typically caused by

A

different fungi than superficial infections

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14
Q

how is subcutaneous mycosis often treated

A

oral administration of azole antifungal agents

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15
Q

2 examples of subcutaneous mycosis

A

sporotrichosis
chromoblastomycosis

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16
Q

what is sporotrichosis an occupational hazard of

A

those working in close contact with soil agriculture workers
miners
gardeners

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17
Q

what does chromoblastomycosis typically form

A

crusty wart like lesions on hand or leg

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18
Q

what is sporotrichosis caused by

A

the saprophyte
sporothrix schenckii

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19
Q

size of the round conidia in sporothrix schenckii

A

2 μM in diameter

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20
Q

what does systemic effect

A

internal organs

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21
Q

where do systemic fungal pathogens normally live

A

in soil

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22
Q

how do systemic fungal pathogens infect humans

A

due to inhaling airborne spores
travels from lungs to other organs and skin

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23
Q

why is chemotherapy difficult to treat systemic mycosis

A

issues with toxicity

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24
Q

who does systemic fungal pathogens primarily affect

A

the elderly or otherwise immune compromised

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25
Q

why do systemic fungal pathogens typically infect elderly/immune compromised

A

age - cell mediated immunity declines
immune system impaired- HIV/AIDS

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26
Q

due to the type of people systemic mycosis infects, what can be said about this type of pathogen

A

opportunistic pathogens

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27
Q

what are opportunistic pathogens

A

cause disease only in those whose immune defense can no longer fight off the fungi

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28
Q

what is primary fungal disease

A

healthy individual infected

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29
Q

what is secondary fungal disease

A

predisposing condition making the individual more susceptible to infections (HIV)

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30
Q

what are the 3 major systemic mycoses in the USA in order in decreasing incidence

A

histoplamosis
coccidiodomycosis
blastomycosis

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31
Q

what is histoplasmosis caused by

A

histoplasma capsulatum (dimorphic)

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32
Q

where is histoplasmosis commonly found

A

rural areas in mid west USA (airborne)

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33
Q

what occurs with the inhaled spores with histoplasmosis

A

inhaled spores germinate and grow in the lung

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34
Q

what is coccidioidomycosis caused by

A

coccidioides immitis (dimorphic)

35
Q

where is coccidioides immitis found

A

desert regions of the south west USA

36
Q

when does coccidioides immitis become airborne

A

when it rains

37
Q

what is coccidioidomycosis a cause of

A

pneumonia

38
Q

what is blastomycosis caused by

A

blastomyces dermatitidis (dimorphic)

39
Q

where is blastomycosis endemic to

A

areas of north america (great lakes)

40
Q

if left untreated what occurs with blastomycosis

A

skin lesions

41
Q

what is paracoccidioidomycosis caused by

A

paracoccidioides brasiliensis

42
Q

where is paracoccidioidomycosis primarily found

A

subtropical disease (south america)

43
Q

what does paracoccidioidomycosis infect

A

intially pulmonary
lesions forming on face or other extremities

44
Q

how is paracoccidioidomycosis treated

A

azoles

45
Q

how is paracoccidioidomycosis treated

A

azoles

46
Q

what is cryptococcosis caused by

A

yeast form of cryptococcus neoformans

47
Q

where can cryptococcosis occur

A

virtually any organ of the body
-initally pulmonary/wound

48
Q

where is crytptococcosis often seen

A

in HIV/AIDs patients

49
Q

what is candida albicans

A

dimorphic yeast often present as a minor component of human normal flora

50
Q

what diseases can candida albicans cause

A

thrush
to serious infections in immunocompromised individuals

51
Q

what can be said of candida albicans genome

A

highly dynamic
chr rearrangements as means of generating genetic diversity

52
Q

what is pneomocytosis pneumonia often caused by

A

pnemocytosis jirovecil

53
Q

examples of the type of people that pneomocytosis infect

A

chemo patients/AIDS
premature/severly malnourished children
elderly
infants with hyper IgM syndrome

54
Q

what do antifungals target

A

ergosterol

55
Q

what are the 2 main classes of ergosterol inhibitors

A

polyenes
azoles

56
Q

what is the mode of action of ergosterol inhibitors

A

target unique fungal plasma membrane component

57
Q

3 steps of how ergosterol inhibitors work

A

bind to ergosterol
destabilising fungal cell membrane
leading to cell death

58
Q

what are polyenes

A

a mol with multiple conjugated double bonds

59
Q

what do polyenes contain at least 3 of

A

alternating double and single carbon-carbon bonds

60
Q

mechanism of action of polyenes

A

bind to sterols in the fungal cell membrane, principally ergosterol

61
Q

what does the mechanism of action of polyenes place the membrane in

A

less fluid
more crystalline state

62
Q

what leaks from the cell leading to cell death with polyenes

A

small organic mols inc. monovalent ions (K ,NA, H, Cl)

63
Q

what are the 3 main classes of azoles

A

imidazoles
triazoles
thiazoles

64
Q

mode of action of azoles

A

inhibit the enzyme lanosterol 14 a-demethylase which converts lanosterol to ergosterol
(except for abafungin)

65
Q

how does depletion of ergosterol in fungal membrane lead to inhibition of fungal growth

A

depletion disrupts the structure and many functions of fungal membranes
accumulation of toxic sterol intermediates

66
Q

what are echinocandins

A

new class of antifungal drugs

67
Q

mode of action of echinocandins

A

inhibit the synthesis of glucan in the cell wall

68
Q

how do echinocandins inhibit synthesis ofglucan in cell wall

A

via inhibiton of enzyme 1,3-b glucan synthase

69
Q

what are beta glucans

A

carbohydrate polymers that are cross linked with other fungal cell wall components

70
Q

what does the inhibiton that echinocandins prevent

A

fungal cell wall synthesis

71
Q

what does depletion of glycan polymers lead to

A

weakened cell wall and osmotic stress

72
Q

what is the source of echinocandins

A

semi synthetic from pnedmocandin
natural cyclic lipopeptide

73
Q

what are DNA synthesis inhibitors

A

nucleic acid analogues
mimicking cellular nucleotides

74
Q

mechanism of action of DNA synthesis inhibitors

A

inhibit enzymes req for DNA synthesis
difficult as eukaryotic

75
Q

example of a DNA synthesis inhibitor

A

flucytosine

76
Q

target of DNA synthesis inhibitors

A

candida infections
cryptococcus neoformans

77
Q

what is flucytosine used in combination with

A

amphotericin B and/or azole antifungals (fluconazole)

78
Q

what can minor infections such as candidal cystitis be treated with

A

flucytosine alone

79
Q

are DNA synthesis inhibitors synthetic or natural

A

synthetic

80
Q

mode of action of mitosis inhibitors

A

interfering with fungal mitosis
(disruption of microtubule aggregation)

81
Q

example of a mitosis inhibitor

A

griseofulvin

82
Q

is griseofulvin toxic or nontoxic

A

relatively nontoxic that can be taken orally but passes through the bloodstream to the skin

83
Q

target of griseofulvin

A

used to treat number of types of dermatophytoses (ringworm)

BM211 microbiology (14 decks)

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