Cutaneous Mycoses Flashcards
Cutaneous Mycoses are caused by a fungi generally called ___? that infect only the keratinized tissues - SKIN, HAIR, and NIALS
Dermatophytes
Note:
Dermatophytes
🐈Secrete keratinase-degrades keratin.
🐈Infections extends deep
into the epidermis.
🐈Rarely invade deeper tissue
🐈
🐈 Associated with humans only.
🐈 Person -to-person transmission through contaminated
objects (comb, hat, etc.)
🐈Elicit relatively mild and chronic infections
🐈Produce few in conidia in culture
Anthropophilic
Ecology of Dermatophytes
To determine the source of infection on??
Anthropophilic
Zoophilic
Geophilic
Associated with animals.
Direct transmission to humans by close contact with animals.
Produce more acute inflammatory infections that tend to
resolve quickly
Zoophilic
🐈Usually found in soil.
🐈Transmitted to humans by direct exposure.
🐈Produce more acuteinflammatory infections that tend to resolve quickly
Geophilic
Three (3) common genera of Dermatophytes
Trichophyton
Miscrosporon
Epidermophyton
Trichophyton spp.
-affects the Hair, skin and nails
T. rubrum
T. tonsurans
T. mentagrophytes
T.equinum (horse)
T. verrocosum (cattle)
Miscrosporon spp.
- affects the Hair and Skin
🩵M. gypseum (most common)
M. canis (dogs and cats)
M. gallinae (fowl)
M. nanum (pigs)
Epidermophyton spp?
-affects the Skin and nails
E. floccosum
Most common causative agent of Dermatomycoses
Candida spp
Dermatophytes growth req and what medium
Growth for 2 weeks at 250C on Sabouraud’s dextrose agar (SDA)
Trichophyton species.
Colonies are cottony to granular
T. mentagrophytes
Trichophyton species.
Colonies are white and cottony surface & deep RED non-diffusable pigment
T. rubrum
Flat, powdery to velvety colony; reddish brown on reverse
T. tonsurans
🩵 Makes both macroconidia and microconidia
T. mentagrophytes
globose and in clusters “grapelike” or
engrape
Microconidia
thin walled,
smooth and cigar-shaped.
Macroconidia
🩵 Produce 4-8 celled cylindrical macroconidia
🩵 Clavate or peg-shaped macroconidia, side of hyphae
T. rubrum
appears as “Birds on fence”
T. rubrum
🩵Macroconidia are variable in shape
🩵Club-shaped
T. tonsurans
Microsporum species spp.
✅Powdery granular colonies
✅Fusiform, moderately thick-walled conidia, rounded tips
Microsporum gypseum
✅Fluffy and white colonies with the reverse side forming lemon-yellow pigment
✅Spindle shaped macroconidia with echinulate thick-walled; with tapering spiny distal end.
Microsporum canis
-Flat velvety colonies, with tan to olive green tinge
-Produces only macroconidia, smooth walled, clavate 2-4 celled, and formed small clusters
Macroconidia only
Epidermophyton floccosum
What mycoses?
-Non-hairy, smooth skin
-Circular (RING) patches with advancing red, vesiculated border & central scaling, pruritic
Tinea corporis
✅ Trichopyton rubrum
✅ Epidermophyton floccosum
Tinea pedis AKA?
(Athletes foot)
✅ Trichopyton rubrum
✅ Trichopyton mentagrophytes
✅ Epidermophyton floccosum
Tinea cruris AKA?
“jock itch”
- on intertriginous area; pruritic
✅ Trichopyton rubrum,
✅ Trichopyton mentagrophytes
✅ Epidermophyton floccosum
Affected are scalp and hair characterized as:
✅ Endothrix: fungus inside hair shaft
✅ Ectothrix: fungus on surface of
hair
What is the infection called?
🩵Tinea capitis
caused by:
✅ Trichopyton mentagrophytes
✅ Trichopyton tonsurans
✅ Microsporum canis
- Nail
- Nails thickened or crumbling distally; discolored; lusterless. Usually associated with Tinea pedis.
Tinea ungium
Trichopyton rubrum,
üTrichopyton mentagrophytes
üEpidermophyton floccosum
- Beard hair
- Erythematous lesions
Tinea barbae
Trichopyton rubrum,
üTrichopyton mentagrophytes
üEpidermophyton floccosum
Tinea ungium also known as?
Onychomycosis
Diagnosis for Cutaneous Mycoses
Microscopic examination
✅10-20% Potassium Hydroxide ✅(KOH) ¤ Calcaflour white
✅ Wood’s Light
Culture
✅ Sabouraud’s agar slants
✅ Mold agar
✅ Incubated for 1-4 weeks at room temperature
