Fungal Infections Flashcards
What fungus causes cutaneous mycoses?
Dermatophytes
What fungus causes cutaneous mycoses, +/- systemic mycoses?
Sporotrichosis
What fungi cause respiratory mycoses, +/- systemic mycoses?
Blastomycosis
Histoplasmosis
Cryptococcosis
Coccidioidomycosis
What are the possible geographic distributions of a dermatophyte regarding how it can be transmitted to a host?
Zoophilic: animal-to-animal
Geophilic: via soil
Anthropophilic: human-to-human
What is required for the pathogenesis of dermatophytosis to occur?
Predisposing factor(s) present on host: skin abrasions, bites, moisture, excessive grooming, immune suppression
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?
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.
You are performing a sticky tape preparation to differentiate between dermatophytes. What morphology should you expect to see for each?
- Microsporum canis
- Microsporum gypseum
- Microsporum nanum
- Trichophyton mentagrophytes
- Trichophyton verrucosum
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
What are the 5 dimorphic fungi and what do they have in common?
Sporotrichosis, Blastomycosis, Histoplasmosis, Cryptococcosis, Coccidioidomycosis; all have the potential to cause a systemic infection
What is Rose Gardener’s disease?
Sporotrichosis fungi live in the acidic soil of rose beds –> cats, humans, dogs, etc., can become infected while digging around in this soil
What is the most common route of infection for sporotrichosis?
Infected cat bites human –> trauma to skin allows fungi to cause infection
What morphology should you expect to see on cytology for sporotrichosis?
Macrophages filled with ovoid yeasts
How can the respiratory fungi cause systemic infection?
By invading host cells, which then get transported through the lymphatic system and blood to other sites in the body by phagocytes
What is the acronym associated with systemic infection by fungi?
B (brain, bone)
E (eyes)
L (lymph nodes)
L (lungs)
S (skin)
Which diagnostic test is dangerous for the respiratory fungi?
Culture (spores are aerosolized)
How should you expect Blastomycosis fungi to appear on cytology?
big, blue, broad-based budding
