Fungal Infections Flashcards

1
Q

What fungus causes cutaneous mycoses?

A

Dermatophytes

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2
Q

What fungus causes cutaneous mycoses, +/- systemic mycoses?

A

Sporotrichosis

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3
Q

What fungi cause respiratory mycoses, +/- systemic mycoses?

A

Blastomycosis
Histoplasmosis
Cryptococcosis
Coccidioidomycosis

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4
Q

What are the possible geographic distributions of a dermatophyte regarding how it can be transmitted to a host?

A

Zoophilic: animal-to-animal

Geophilic: via soil

Anthropophilic: human-to-human

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5
Q

What is required for the pathogenesis of dermatophytosis to occur?

A

Predisposing factor(s) present on host: skin abrasions, bites, moisture, excessive grooming, immune suppression

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6
Q

A 4-year-old, MN german shepherd presents with alopecia, erythema (red skin), crusts and pustules on his snout and paws. You suspect dermatophytosis, so you perform a Wood’s Lamp diagnostic. What should you expect to see to support your differential? What precautions should you take?

A

The UV light should reveal a distribution that matches the lesion you see without it. However, the Wood’s Lamp is not very sensitive (only 40% of M. canis will fluoresce) or specific.

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7
Q

You are performing a sticky tape preparation to differentiate between dermatophytes. What morphology should you expect to see for each?

  1. Microsporum canis
  2. Microsporum gypseum
  3. Microsporum nanum
  4. Trichophyton mentagrophytes
  5. Trichophyton verrucosum
A

1-4 = Macroconidia
1. Microsporum canis: tapered ends
2. Microsporum gypseum: blunt, round ends
3. Microsporum nanum: two little cells within it
4. Trichophyton mentagrophytes:
elongated and pipe-like

5 = Chlamydoconidia
5. Trichophyton verrucosum: conidia, lined up in rows

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8
Q

What are the 5 dimorphic fungi and what do they have in common?

A

Sporotrichosis, Blastomycosis, Histoplasmosis, Cryptococcosis, Coccidioidomycosis; all have the potential to cause a systemic infection

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9
Q

What is Rose Gardener’s disease?

A

Sporotrichosis fungi live in the acidic soil of rose beds –> cats, humans, dogs, etc., can become infected while digging around in this soil

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10
Q

What is the most common route of infection for sporotrichosis?

A

Infected cat bites human –> trauma to skin allows fungi to cause infection

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11
Q

What morphology should you expect to see on cytology for sporotrichosis?

A

Macrophages filled with ovoid yeasts

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12
Q

How can the respiratory fungi cause systemic infection?

A

By invading host cells, which then get transported through the lymphatic system and blood to other sites in the body by phagocytes

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13
Q

What is the acronym associated with systemic infection by fungi?

A

B (brain, bone)
E (eyes)
L (lymph nodes)
L (lungs)
S (skin)

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14
Q

Which diagnostic test is dangerous for the respiratory fungi?

A

Culture (spores are aerosolized)

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15
Q

How should you expect Blastomycosis fungi to appear on cytology?

A

big, blue, broad-based budding

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16
Q

How should you expect Histoplasmosis fungi to appear on cytology?

A

small yeast inside of macrophages

17
Q

How should you expect Cryptococcosis fungi to appear on cytology?

A

narrow-based budding surrounded by capsule

18
Q

How should you expect Coccidioidomycosis fungi to appear on cytology?

A

endospores (sac-like structure filled with spores)