32 terms

Superficial & Dermatophytic Fungi

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Exophiala werneckii, "BLACK YEASTY COLONY"
Covered with short olive-gray mycelium, blastoconidia (candida)/anneloconidia stages (aureobasidium), causes tinea negra-brown-black patches on palms
Malassezia furfur, "SPAGHETTI & MEATBALLS"
grows on SABHI with olive oil at 37, thick round-oval cells in clusters with short angular hyphae, causes pityriasis versicolor-different colored patches
Piedraia hortai
greenish-black glabrous colony, dark thick walled hyphae, causes black piedra-black nodules around scalp hairs
Trichosporon beigelii
cream colored wrinkled glabrous colony, blastoconidia/arthroconidia formed, causes white piedra-light brown nodules around beard & mustache hairs
What are the three genera of Dermatophytes?
Microsporum, Epidermophyton & Trichophyton
Ectothrix vs Endothrix hair invasion
Ectothrix refers to fungal infection of outer hair sheath vs Endothrix refers to fungal infection of inner hair sheath
Microsporum species generally
affect skin & ectothrix hair, hair fluoresces
Epidermophyton species generally
invades skin & nails
Trichophyton mentagrophytes, rubrum, and verrucosum generally
affect skin, nails & ectothrix hair
Trichophyton tonsurans, schonleinii and violaceum generally
affect skin, nails and endothrix hair
Microsporum audouinii is a
slow grower
Trichophyton mentagrophytes is a
intermediate grower
Microsporum species vs Trichophyton species
intermediate growers vs slow growers
What are the characteristics of Microsporum species?
Thick or thin walled, elliptical or spindle shaped macroconidia with 3-7 cells and few club shaped microconidia
What are the characteristics of Epidermophyton species?
Smooth, thin walled club shaped macroconidia with 2-4 cells and no microconidia
What are the characteristics of Trichophyton species?
rare, thin walled pencil shaped macroconidia with 3-8 cells and round, oval or club shaped microconidia in grapelike clusters or singly
Microsporum audouinii-fluorescence
sg, light tan velvety or matted with salmon reverse, rare irregular macroconidia & club shape microconidia, terminal pointed vesicle and poor growth on rice grains
causes dermatophytosis of body and scalp
Microsporum canis-fluorescence
ig, white wooly colony with bright yellow reverse, many rough thick spindle macroconidia with few club shaped microconidia,
causes dermatophytosis of the body and scalp-from dogs & cats
Microsporum gypseum
ig, powdery-cinnamon colony with tan reverse, ellipitical shaped macroconidia and few microconidia,
causes inflammatory dermatophytosis of body or scalp via soil
Epidermophyton floccosum
ig, velvety khaki coloney with tan reverse, many club shaped, smooth & thin walled macroconidia, no MICROCONIDIA,
causes epidemic athlete's foot in summer and of nails/groins
Trichophyton mentagrophytes
ig, fluffy white colony with colorless or red reverse/granular colony with rose tan, brown, red or yellow reverse, many pencil shaped, smooth, thin macroconidia, with many-few round microconidia in clusters, positive UREASE & PERFORATES HAIR,
causes inflammatory dermatophyosis of foot, body, nails, beard and scalp
COMMON CAUSE OF ATHLETE"S FOOT
Trichophyton rubrum
sg, granular-white colony with pink periphery and DEEP RED REVERSE, many-few pencil shaped macroconidia and many club shaped microconidia, NEGATIVE UREASE & NO HAIR PERFORATION
causes dermatophytosis of body, foot, groin & nails
Trichophyton verrucosum
sg - at 37C, thiamine grower, waxy white to bright yellow coloney with nonpigmented or yellow reverse, on thiamine media-rare MACROCONIDIA with RAT TAIL and moderate club shaped microconidia
causes dermatophytosis of scalp, beard, or body-from cattle
Trichophyton schoenleinii
sg, waxy-light yellow colony with yellow orange reverse-colorless, no macroconidia, FAVIC CHANDELIERS,
causes severe dermatophytosis of scalp and rarely of body/nails
Trichophyton tonsurans
sg, three colony types; gray-white, suede front with mahogany reverse; granular white with colorless reverse; bright yellow-granular suede rugose colony with yellow reverse
rare smooth club shape macroconidia and numerous shaped microconidia
UREASE POSITIVE & DOES NOT PERFORATE HAIR
causes dermatophytosis of scalp
Trichophyton violaceum
sg, waxy or suede, violet colony with lavender reverse, no macroconidia, requires THIAMINE for growth
causes dermatophytosis of scalp & body, rarely foot, nails or deep infections
What are causative agents of Dermatophytosis of the scalp?
"Tinea capitis"-Caused by any Microsporum species & Trichophyton (except T. concentricum) and RARELY Exophiala werneckii
What are causative agents of Dermatophytosis of the body?
"Tinea corporis"-Caused by M. audouinii, canis, gypseum & T. mentagrophytes, rubrum, verrucosum, violaceum, RARELY T. tonsurans & schoenleinii
What are causative agents of Dermatophytosis of the beard?
"Tinea barbae, barber's itch"-Caused by M. canis, T. mentagrophytes, rubrum, verrucosum, violaceum
What are causative agents of Dermatophytosis of the groin?
"Tinea cruris, jock itch" -Caused by Epidermophyton floccosum, T.mentagrophytes, rubrum, Candida and RARELY E. wernecki
What are causative agents of Dermatophytosis of the foot?
"Tinea pedis, athlete's foot"-Caused by E.floccosum, T.mentagrophytes, T. rubrum, C. albicans, and RARELY T. tonsurans, violaceum, werneckii
What are causative agents of Dermatophytosis of the nail?
"Tinea unguium, onychomycosis"-Caused by E. floccosum, E.mentagrophytes, T. rubrum, C. albicans, and RARELY T. tonsurans, violaceum, schoenleinii, M. canis & E. werneckii