Mycology Flashcards from Bottom Line Approach

How do fungi undergo sexual reproduction?

Fusion of 2 haploid nuclei; spores - teleomorph

How do fungi undergo asexual reproduction?

Mitotic division of haploid nucleus and budding production of conidia - anamorph

What is hyphae?

Tube-like structures with thick parallel walls

Septate

Contain cross walls

Aseptate

Rare cross walls

What are pseudohyphae?

Elongated budding yeast cells with constrictions between cells

What are condida?

Spores

What are the methods of fungal infection?

Inhalation - most common

Trauma-induced

Contact - direct and indirect

What does 10% KOH wet prep do?

Clears debris and breaks down keratin from hair and nails; use with specimen

What does lactophenol cotton blue (LPCB) do?

Stains and kills organisms; use with culture material

What does india ink do?

Stains capsule of Cryptococcus neoformans

What does calcofluor white do?

Fluorescent

What are the types of primary growth agar?

Sabouraud dextrose agar (SDA) and Mycosel

What is Sabouraud dextrose agar (SDA)?

Primary growth agar; contains glucose and peptones; pH = 5.6

What is Mycosel?

Primary growth agar; contains cycloheximide and chloramphenicol

What does cyclohexamide do?

Inhibits fast growing fungi

What does chloramphenicol do?

Inhibits bacterial growth

What are the specialty growth medias?

Bird seed agar (Cryptococcus neoformans) and corn meal agar (Candida albicans)

What is the optimal temperature for fungi collection and handling?

25-30C

How long can you hold fungi?

4-6 weeks

What should you use to prevent accidental openings and drying?

Screw-cap tubes or tape plates

How should you handle fungi samples?

Under a biological safety hood

What are dermatophytes?

Keratinophilic - adapted to grow on hair, nails, and skin

How are dermatophytes transmitted?

Person to person

What clinical infections come from dermatophytes?

Ringworm = tinea

• Foot = Tinea pedis

• Groin = Tinea cruris

• Body = Tinea corpus

• Beard = Tinea barbae

• Nail = Tinea unguium

  • Scalp = Tinea capitis

How to prep dermatophytes?

KOH prep of scales from advancing margin of lesion, hair, or nails

Why is the Wood’s lamp used?

Some dermatophytes fluoresce under UV light (Microsporum)

How are dermatophyte infections treated?

Miconazole, clotrimazole, griseofulvin

What does microsporum affect?

Hair and skin; mostly children

Macroconidia (Microscporum)

Large, spindle shaped, rough with 4-15 septa

Microconidia (Microsporum)

Small, club shaped

What does M. audouinii cause?

Tinea capitis

How long is M. audouinii given to grow?

10-20 days

What do M. audouinii hairs fluoresce?

Yellow-green

What does M. canis cause?

Dog and cat ringworm (passed to humans)

Macroconidia (M. canis)

Abundant with 4-8 septa, knoblike, echinulate (rough) ends, thick walls

How long is M. canis given to grow?

4-5 days

Macroconidia (M. gypseum)

Many macroconidia with 3-5 septa and echinulate surface (rounded ends), thin walls, fusiform

What does trichophyton affect?

Skin, hair, and nails; primarily adults

How many microconidia and macroconidia does trichophyton have?

Microconidia = many

Macroconidia = few or none (thin, smooth walls)

What does T. mentagrophytes cause?

Athletes foot (Tinea pedis)

Microconidia (Trichophytons)

Numerous, spiral and nodular bodies, white-cottony mycelium

When does T. mentagrophytes turn urease positive?

Within 2-3 days