Fungal Infections Mycology Flashcards

1
Q

what is fungi

A

uni or multicellular organisms

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2
Q

is fungi aerobic or anaerobic

A

aerobic eukaryotes

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3
Q

do fungi have a defined or undefined nuclei

A

defined nuclei

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4
Q

what are the cell walls of fungi made up of

A

carbohydrate and chitin

ergosterol in plasma membrane

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5
Q

are fungi saprophytic or parasitic

A

can be both

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6
Q

how do fungi reproduce

A

sexual or asexual reproduction

asexual spores by mitosis –> infectious forms of hyphal fungi

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7
Q

what is the importance of fungi in veterinary medicine

A
  1. allergy (fungal spores)
  2. cutaneous and superficial mucous membranes (dermatophytes, melessezia, candida infection)
  3. subcutaneous (sporotrichosis)
  4. systemic –> primary pathogens (histoplasma), opportunistic pathogens (aspergillus)
  5. toxins (mycotoxins)
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8
Q

how is fungi diagnosed

A

laboratory diagnosis

clinical specimens –> skin, hair, nails, swabs from mucous membranes, blood etc

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9
Q

what are the methods of laboratory diagnosis

A
  1. direct microscopy: skin, hair, nails, KOH preps, calcofluor white, gram stain on colonies, giemsa
  2. culture: sabarauds dextrose agar, chromagar, specialized agars, days or weeks –> identification by morphology of hyphae, production of spores, PCR, histology of tissue in invasive disease
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10
Q

what is yeasts

A

unicellular organisms that reproduce by budding

grow on skin, mucous surfaces and in the body

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11
Q

what are moulds

A

multicellular organisms that produce hyphae and myeclium and spores (dematophytes –> hyphae grow in skin, hair and nails

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12
Q

what are dimorphic fungi

A

organisms that can produce both hyphae and yeast like forms

hyphae in environment (+ spores) and yeasts in the infected host –> geographically restricted

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13
Q

how do yeasts grow

A

by division

budding

binary fission

somtimes the daughter cells may not detach themselves –> result is pseudohyphae (pseudo and true hyphae –> Candida albicans)

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14
Q

what are species of yeasts

A

candida

malassezia

cryptococcus

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15
Q

is candida gram + or -

A

gram positive

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16
Q

what are the shape of candida

A

oval cells

3-6 micromilimeters

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17
Q
A
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18
Q

what do candida form

A

germ tubes

chlamydospores

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19
Q

what do candida grow on in lab

A

37C on sabouraud’s dextrose agar/chromogenic agar

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20
Q

what do candida look like in culture

A

creamy white colonies

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21
Q

what species is this

A

candida

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22
Q

what is candida albicans in cattle

A

causes mycotic abortion

rumenal infections

mastitis

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23
Q

what does candida albicans in pigs

A

dermatitis

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24
Q

what does candida albicans in dogs cause

A

chronic enteritis and dermatitis

vaginitis/vulvitis in diabetes

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25
Q

what does candida albicans in birds cause

A

crop infections, enteritis

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26
Q

what does candida albicans in man cause

A

mucosal and systemic infections

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27
Q

what is malassezia

A

bottle shaped

malassezia pachydermatis

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28
Q

what does malassezia grow on

A

sabouraud’s dextrose agar at 37C

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29
Q

what does malassezia cause

A

ottis externa

dermatitis

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30
Q

what species is this

A

malassezia

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31
Q

what is cryptococcus

A

C. neoformans

C. grubii

C. gattii

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32
Q

what infections does cryptococcus cause

A

opportunistic infections

defective cell mediated immunity

meningitis

nasal cavity of cats with chronic rhinitis

nasal, cutaneous, neural and ocular disease in cats

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33
Q

what species is this

A

cryptococcus

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34
Q

what are filamentous hyphal fungi (moulds)

A

multicellular, multinucleate

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35
Q

what is the basic unit of moulds

A

hyphae, a long filament

hyphae branch and cross link to form a mat (mycelium)

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36
Q

where does growth occur in filamentous hyphal fungi

A

growth occurs at hyphal tip

hyphae may be divided by cross-walls (septa) into uninuclear units

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37
Q

what are non septate hyphae

A

coenocytic

38
Q

what do septa contain

A

pore

all cytoplasm is connected

39
Q

what species is this

A

filamentous hyphal fungi (moulds)

40
Q

what is dermatophytes

A

microsporum, trichophyton sp

41
Q

what are the features of dermatophytes

A

septate branching hyphae

antropophilic, geophilic, zoophilic

42
Q

what do dermatophytes digest

A

digest keratin –> infect skin, hair and nails

43
Q

what spores do dermatophytes form in clinical specimens

A

arthrospores

44
Q

what spores do dermatophytes form in lab culture and what do they grow on

A

microconidia and macroconidia

grow on sabouraud’s within 7-14 days at 28C

45
Q

what species is this

A

dermatophytes - microsporum, trichophyton

46
Q

what is the difference between ectothrix and endothrix

A

ectothrix: fragmentation of the mycelium into conidia around the hair shaft or just beneath the cuticle of the hair, with destruction of the cuticle
endothrix: infections of the hair that invade the hair shaft and internalize into the hair cell.

47
Q

what type of infections are these

A

ectothrix top

endothrix bottom

48
Q

what is microsporum

A

ringworm in man and animals

anthropophilic, zoophilic, geophilic

microconidia en thyrse –> along sides of hyphae

may fluoresce under wood’s light

49
Q

what is M. canis

A

ringowrm in cats and dogs

transmissible to man

50
Q

where does M. canis grow

A

on hair with arthospores –> ectothrix

51
Q

what does M. canis appear on culture

A

macroconidia elliptical with up to 14 divisions, rare on isolation

fluoresces

colonies smooth white surface, yellow underside

52
Q

what is this

A

microsporum canis

53
Q

what are other microsporum species

A

M. gypseum –> many macroconidia, dog, geophilic

M. nanum –> pigs

54
Q

what is trichophyton

A

zoophilic

ringworm in man and animals

55
Q

what is the shape of trichophyton

A

club-shaped macroconidia

microconidia en thyrse and en grappe

spiral hyphae

no fluorescence

56
Q

what are the species of trichophyton

A

T. verrucosum –> ringworm in cattle transmissible to man

T. mentagrophytes –> dog, horse

T. equinum –> horse

T. gallinae –> fowl

57
Q

what is T. verrucosum abundant in

A

chlamydospores

large spore ectothrix on hair

colonies slow growing –> deep in agar

58
Q

what species is this

A

T. verrucosum

cattle

59
Q

what species is this

A

trichophyton verrucosum

60
Q

what species is this

A

T. equinum

61
Q

what species is this

A

T. mentagrophytes

62
Q

what species is this

A

T. mentagrophytes

63
Q

what is the structure of aspergillus

A

septate branching hyphae

sporing heads or conidia in oxygen

conidiophore and sterigmae

use colonial appearance, size and details of conidiophore to identify

64
Q

what species is this

A

aspergillus

65
Q

where is aspergillus fumigatus

A

on food, fodder

spores infect young non-immune or immunosuppressed animals

66
Q

where does aspergillus fumigatus grow

A

sabouraud’s at 24-28C

67
Q

what is the shape of aspergillus fumigatus

A

star shaped colonies

green blue with sporing heads

histopathological evidence of tissue invasion

68
Q

what species is this

A

aspergillus fumigatus

69
Q

what is aspergillus disease (hatched chicks, birds, horses, dogs, cows, man)

A

mainly respiratory infection –> spore inhalation

pneumonia in newly hatched chicks

air sacculitis in birds

guttoral pouch mycosis in horses

nasal aspergillosis in dogs

mycotic abortion in cows –> poor quality feed

man –> allergic disease and severe infection in immunocompromised

70
Q

what are the host defences against aspergillus in the lung (9)

A
  1. inactive conidia are inhaled
  2. conidia lodge in lower respiratory tract
  3. conidia swell
  4. blocked by macrophages
  5. conidia germinate into hyphae
  6. blocked by neutrophils
  7. hyphae invade tissues
  8. blocked by neutrophils
  9. hyphae invade blood vessels and disseminate
71
Q

what is this

A

aspergillus in bovine lung

72
Q

what is this

A

aspergillus in airsacs

73
Q

what are 2 distinct forms of dimorphic fungi

A

mould and yeast

74
Q

where is dimorphic mould and yeasts found and how do they enter the host

A

moulds in environment

yeast in animal tissue –> pathogenic form

spores enter host by respiratory route (or skin)

75
Q

what disease do dimorphic fungi cause

A

histoplasma capsulatum

blastomyces dermatitidis

coccidioides immitis

sporothrix schenckii

76
Q

what is histoplasma capsulatum

A

endemic in mississippi and ohio river valleys

man dogs and cats

impaired CMI (cell mediated immunity)

granulomas in lungs

infection of macrophages

77
Q

what disease is this

A

histoplasma capsulatum

78
Q

what does histoplasma capsulatum farcinimosum cause (how does it entre, what species, where is it found, what does it grow in)

A

epizootic lymphangitis

spores entre through skin

ulcers over lymphatics and lymph nodes

horses

notifiable, category 3

india, africa, middle east

grows at 30C in serum rich media

79
Q

what is subcutaneous disease caused by

A

sporotrichosis (sporothrix schenckii)

natural infection of animals (cats) and humans –> cutaneous and systemic

80
Q

what species is this

A

sporotrichosis

subcutaneous disease

81
Q

what is zygomycetes

A

broad hyphae non-septate

82
Q

how does zygomycetes reproduce

A

asexual spores in sporangium

sexual spores oospores or zygospores

83
Q

what infections does zygomycetes cause

A

Mucor, Rhizopus, Absidia, Saprolegnia

infection uncommon in healthy immunocompetent animals

immunodeficiency, steroids, antibiotics

84
Q

what does zygomycetes cause

A

abortion in cattle

rumenitis

85
Q

what is this

A

zygomycetes

86
Q

what are mycotoxins

A

secondary metabolites of fungal species in crops, pasture or stored feed

87
Q

what do mycotoxins cause

A

non-antigenic, immunosuppression, mutagenic, teratogenic, carcinogenic

88
Q

what is alfatoxin

A

difuranocoumarins

aspergillus species

alfatoxicosis –> absorption from GI tract, metabolized by liver to toxic product –> carcinogenic

89
Q

what is ergotism

A

ergopeptide alkaloids

claviceps purpurea

domestic animals and humans

seed heads of grasses and cereals –> ergotamine and argometrine

affect nerves supplying arteriolar smooth muscles

90
Q

what is mycotic estrogenism

A

zearalenone

potent non steroidal estrogen produced by fusarium sp

maize and other cereals

reproductive problems in cattle and sheep