33 – Fungal Fundamentals Flashcards

1
Q

Microbiological characteristics

A
  • Eukaryotes (more similar to us than bacteria)
  • Nucleated
  • Fungal hyphae
  • Cell membrane: ERGOSTEROL
  • Very few encountered as pathogens
  • *moulds and yeasts (morphological terms)
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2
Q

What is fungal hyphae?

A
  • Cell walls composed of chitin
  • *can target with anti-fungal drugs
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3
Q

How do you visualize them?

A
  • KOH wet prep
  • Transparency tape preparation
  • India ink
  • Methylene blue
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4
Q

Mold vs yeast

A
  • *don’t think of them as separate branches
  • Mostly morphological terms
  • *some are dimorphic (yeast at 35 degree C, mould at colder temperatures)
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5
Q

Lifestyles

A
  • Aerobic
  • Most grow at low temperatures (20-30 degree C)
  • Tolerant of high pressures and low pH
  • Capable of growing a wide variety of environments
  • Very good at degrading polymers
  • Some found using radiation as energy
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6
Q

Fungi makes yummy food and drinks for us: example of Roquefort cheese

A
  • Produces toxin: roquefortine toxin=poisonous to dogs
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7
Q

Fungi makes useful things: example

A
  • Penicillin from penicillium-species of mold
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8
Q

Virulence factors: ‘3 presentations you can get’

A
  • Tissue invasion: mycosis
  • Toxin production: mycotoxicosis
  • Hypersensitivity
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9
Q

Mycosis

A
  • *tissue invasion
  • What you might think of when you think ‘infection’
  • Ex. guttural pouch mycosis
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10
Q

What are some different mycotoxicosis?

A
  • Aflatoxicosis
  • Fusariotoxicosis
  • Ergotism
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11
Q

Aflatoxicosis: example

A
  • Aflatoxins in feed affect poultry
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12
Q

Fusariotoxicosis: example

A
  • Zearalenone is NON-toxic for poultry but causes disease in PIGS
    o Reproduction in pigs
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13
Q

Ergotism: example

A
  • Alkaloids produced by fungi growing on cereals
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14
Q

Hypersensitivity (‘virulence factor’)

A
  • Moulds growing in damp buildings
  • Exacerbation of asthma or hypersensitivity pneumonitis
  • Ex. disaster clean up
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15
Q

Classification of fungi is a state of flux

A
  • Classically based on morphology and sexual reproductive life cycle
  • *increasingly relying on DNA sequence
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16
Q

What is some vocab used in taxonomy?

A
  • Hyphae
  • Mycelium
  • Asexual spores
17
Q

Hyphae

A
  • Filaments which make up mycelium
18
Q

Mycelium

A
  • Mat of branching hyphae
19
Q

Asexual spores

A
  • Disseminate to other locations, germinate when conditions are FAVORABLE
    o Spores in/on different structures have different morphologies
    o Many different types
20
Q

Clinical significance

A
  • Relatively few are pathogenic
    o Majority grow best below body temperature of endotherms
  • *opportunistic and not contagious
  • Common cause of disease in ectotherms (plants, insects, fish, amphibians)
21
Q

In mammals, what are fungi typically considered? (2)

A
  • Commensal/host-associated
    o Disease happens in states of IMMUNOSUPPRESSION
  • Environmentally acquired
    o Disease typically follows exposure
22
Q

Environmentally acquired: examples

A
  • Many of the dimorphic fungi (ex. Blastomyces)
  • Disease typically follows exposure to LARGE INOCULUM
  • Understanding geographic distribution is IMPORTANT
23
Q

‘nuclear winter’ from asteroid killed off plant life

A
  • Dead plants broken down my fungi!
    o Massive plume of spores
  • Nothing to eat for dinosaurs and needed sun to worm up
    o Disease when overwhelming challenge and compromised host defenses
  • *perfect example of epidemiological triad
  • *birds (beaks to eat seeds/nuts) and early mammals survived
24
Q

What is an example of fungal disease and extinction?

A
  • White nose syndrome in NA bats (Pseudogymnoascus destructans)
  • Chytridiomycosis in amphibians
  • Snake fungal disease: emerging disease in US
25
Q

What are risk factors are infections in people most commonly associated with?

A
  • Immunosuppression
  • Organ transplant recipients
  • SLE (lupas), vascular diseases, diabetes mellitus, alcholics
  • Iatrogenic factors
  • AIDS
26
Q

What are some iatrogenic factors that are a risk factor in humans for infection?

A
  • Prolonged antimicrobial, steroid or cytotoxic therapy