7. Dermatophytes Flashcards
Animal to human route of infection
Zoophilic
Person to person route of infection
Anthropophilic
Infection of facial hair
Tinea barbae (Barber’s itch)
Infection of the scalp
Tinea capitis
Infection of the arms, legs, and trunk
Tinea corporis (ringworm)
Infection of the groin area
Tinea cruris (Jock itch)
Infection of the face
Tinea faciei
Infection of the hands
Tinea manuum
Infection of the spaces between toes
Tinea pedis (Athlete’s foot)
Infection of the fingernails ans toenails
Tinea unguinum
Infection of the hair follicle, crusty lesions
Favic
Infection that colonizes the outside part of the hair shaft
Ectothrix
Infection of the hair follicle first, then grows inside the shaft
Endothrix
Infection of the nail and nail bed
Onchomycosis
Specimens for dermatophyte ID
Hair
Hair scraping
Nail scraping or clipping
Modification of KOH preparation for dermatophyte ID
Calcofluor
Temp and time for growth of dermatophytes
30°C for 4 weeks on SDA
3 major genera under Dermatophytes
Microsporum
Epidermophyton
Trichophyton
Macroconidia: rare, thin-walled, smooth
Microconidia: numerous
Trichophyton
Macroconidia: numerous, thick-walled, rough
Microconidia: usually present
Microsporum
Macroconidia: numerous, thin- and thick-walled, smooth
Microconidia: not formed
Epidermophyton
Geophilic dermatophytes
Microsporum gypseum
Microsporum nanum
Trichophyton rubrum
Zoophilic dermatophytes
Microsporum canis
Trichophyton mentagrophytes
Anthropophilic dermatophytes
Microsporum audouinii Epidermophyton floccosum Trichophyton mentagrophytes Trichophyton tonsurans Trichophyton schoenleinii
Has rare distorted macroconidia, rare microconidia
Microsporum audouinii
No growth on sterile rice media
Microsporum audouinii
Has large spindle-shaped macroconidia (3-15 cells, tapering ends)
Microsporum canis
Has “rowboat”-shaped macroconidia
Microsporum gypseum
Powdery/granular buff to brown colony
Microsporum gypseum
Rare cause of tinea corporis in humans
Microsporum nanum
Causes tinea cruris, pedis, and unguium
Epidermophyton floccosum
Has khaki-yellow colonies
Epidermophyton floccosum
As smooth-walled, club-shaped, groupings of macoconidia (beaver’s tail)
Epidermophyton floccosum
Infects all 3 keratinized tissues
Trichophyton mentagrophytes
Most common cause of athlete’s foot
Trichophyton mentagrophytes
Has spiral hyphae
Trichophyton mentagrophytes
Microconidia: round, clustering
Macroconidia: cigar-shaped
Trichophyton mentagrophytes
Perforates hair
Trichophyton mentagrophytes
Urease positive
Trichophyton mentagrophytes
Ectothrix dermatophyte
Trichophyton rubrum
Endothrix dermatophytes
Trichophyton tonsurans
Trichophyton schoenleinii
Tear-drop shaped microconidia
Trichophyton rubrum
“Black dot” tinea capitis
Trichophyton tonsurans
Vitamin needed by Trichophyton tonsurans
Thiamine
Dermatophyte that requires thiamine
Trichophyton tonsurans
Has antler-shaped hyphae
Trichophyton schoenleinii
Soil to man route of infection
Geophilic