Cutaenous mycoses Flashcards
Causative agent of tinea favosa/farvus
T. schoenleinii
Tinea favosa/farvus appearance
Yellow crusty cup-shaped flakes (scutula) on head
Macroscopic colony appearance of T. schoenleinii
Irregularly heaped, smooth, white to cream, with radiating grooves; reverse white
Hyphal structure of T. schoenleinii
Hyphae become knobby and club-shaped at the terminal ends, with short lateral and terminal branches
Trichophyton mentagrophytes
Tinea capitis, tinea corporis, tinea pedis, tinea unguium
Colony appearance of T. mentagrophytes
Velvety and fluffy or granular and flat; white or tan to pink; reverse white, rose, or red-brown
Microconidia of T. mentagrophytes
Numerous, small, globose, arranged in grape-like clusters
Macroconidia of T. mentagrophytes
Rare, thin-walled, smooth, cigar-shaped
Urease test for T. mentagrophytes
Positive
Hair-baiting test for T. mentagrophytes
Produces wedge shapes in hair
Growth on Trichophyton agars
Grows on Trichophyton agars Nos. 1, 2, 3, and 4
Microsporum gypseum
Tinea capitis, tinea corporis, tinea unguium
Colony appearance of M. gypseum
Flat, tan to brown or cinnamon-brown, granular or powdery; reverse side rose-brown, red-brown, or cinnamon
Microconidia of M. gypseum
Sparse, clavate, smooth-walled
Macroconidia of M. gypseum
Numerous, thick-walled, cigar-shaped, multiseptate, spiny surfaces, rounded tips
Growth on rice grain for M. gypseum
Grows in rice grain
Trichophyton tonsurans
Tinea capitis, tinea corporis, tinea pedis, tinea unguium
Colony appearance of T. tonsurans
Flat, powdery, granular; cream, tan, yellow-rose, or rust-colored; colonies become heaped or sunken with folds; reverse yellow to tan
Microconidia of T. tonsurans
Abundant, tear-, club-, or balloon-shaped
Macroconidia of T. tonsurans
Rare, smooth-walled, cylindrical
Growth on Trichophyton agars for T. tonsurans
Requires thiamine; grows well on Trichophyton agars Nos. 3 and 4; fails on Nos. 1 and 2
Hair involvement in T. tonsurans
Black-dot ringworm, Endothrix hair involvement
1 cause of fungal scalp infection
Tinea capitis
Trichophyton rubrum
Tinea capitis, tinea corporis, tinea unguium
Colony appearance of T. rubrum
Fluffy or granular white to pink colonies; reverse side cherry red or wine red on cornmeal agar
Microconidia of T. rubrum
Tear-shaped, borne laterally from long strands of hyphae; resemble ‘birds on a fence’
Macroconidia of T. rubrum
Rare, thin-walled, smooth, pencil-shaped
Hydrolysis of urea, hair-baiting test, and growth on Trichophyton agars for T. rubrum
Rarely hydrolyzes urea (requires 7 days for observable reaction); negative hair-baiting test; grows on Trichophyton agars Nos. 1, 2, 3, and 4
Epidermophyton floccosum
Onychomycosis, Tinea corporis, Tinea pedis
Colony appearance of E. floccosum
White to tan colonies, yellow to mustard-yellow or khaki-green with age; flat, suede-like texture with folded center; reverse side yellow-brown or dark orange with folds
Microconidia of E. floccosum
Absent
Macroconidia of E. floccosum
Numerous, club-shaped, spatulate, beaver’s tail, with 2-4 cells, occurring singly or in clusters of 3-4; 10% KOH
Microsporum audoinii
Gray-patch ringworm, Ectothrix hair involvement, Tinea capitis, Tinea corporis
Colony appearance of M. audoinii
Cream, tan, buff, or light brown, flat, velvety colony; reverse side salmon pink or orange-brown
Microconidia of M. audoinii
Rare
Macroconidia of M. audoinii
Bizarre-shaped, thick-walled, spindle, and multiseptate with rough surface; terminal chlamydospores
Test for M. audoinii
Woods lamp: apple-green fluorescence; 10% KOH; No growth in rice grain
Microsporum canis
Tinea capitis, Tinea corporis
Colony appearance of M. canis
White to buff granular or cottony surface with bright yellow periphery; reverse side lemon-yellow or yellow-orange
Microconidia of M. canis
Clavate, smooth-walled, laterally attached to hyphae
Macroconidia of M. canis
Thick-walled, spindle-shaped, multiseptate, rough-walled with curved tip and knobby projections
Test for M. canis
Woods lamp: green-yellow fluorescence; spindle-shaped macroconidia; grows in rice grain
Beard and mustache infections; usually zoophilic and an occupational hazard for farm workers
Tinea barbae
Fungal species causing Tinea barbae
T. mentagrophytes, T. verrucosum, Microsporum canis
Common in children, Ectothrix infection
Tinea capitis (Gray-patch ringworm)
Fungal species causing Gray-patch ringworm
Microsporum canis, Microsporum audouinii
Endothrix infection
Tinea capitis (Black-dot ringworm)
Fungal species causing Black-dot ringworm
Trichophyton tonsurans
Tinea capitis (Inflammatory type)
Ectothrix infection
Fungal species causing inflammatory Tinea capitis
Trichophyton mentagrophytes
Hair follicle at its base, rusty cup-shaped flakes (scutula) in the head
Tinea favosa (T. schoenleinii)
Geophilic infections; associated with Microsporum canis, M. gypseum, Trichophyton rubrum, T. tonsurans
Tinea corporis (Body, especially the trunk)
Distinctive lesion seen in individuals living in isolated tropical environments
Tinea imbricata (T. concentricum)
Common in athletes, military personnel, and those sharing towels/clothing; caused by Epidermophyton floccosum, Trichophyton rubrum, T. mentagrophytes
Tinea cruris (Groin)
Itchy, round patches on the back of the hands and dry, thickened skin on palms; caused by Trichophyton rubrum
Tinea manuum (Hands, palms, and fingers)
Common on soles of feet and between toes, characterized by itching, scales, and possible seeping; caused by T. mentagrophytes, T. rubrum, E. floccosum
Tinea pedis (Feet, Athlete’s Foot)
Infection begins at the edge of the nail and causes thickening and brittleness; caused by T. rubrum, T. mentagrophytes, E. floccosum
Tinea unguium (Nails, Onychomycosis)
Epidermophyton: Skin and Nails, Microsporum: Skin and Hair, Trichophyton: Skin, Hair, Nails
Dermatophytes Classification
Mycosel agar/Mycobiotic agar; microscopic examination: Large, smooth-walled club-shaped MACROCONIDIA; colony khaki colored
Epidermophyton floccosum
Mycosel agar/Mycobiotic agar; microscopic examination: Large rough-walled, many-celled MACROCONIDIA; microconidia few or absent; spindle-shaped with curved tips; reverse colony orange or yellow
Microsporum canis
Mycosel agar/Mycobiotic agar; microscopic examination: Large rough-walled, many-celled MACROCONIDIA; microconidia few or absent; broadly spindle-shaped with rounded ends; colony cinnamon colored
Microsporum gypseum (Nannizzia gypsea)
Mycosel agar/Mycobiotic agar; microscopic examination: Large rough-walled, many-celled MACROCONIDIA; microconidia few or absent; rare bizarre-shaped, only terminal chlamydospores; colony salmon colored, no growth on rice medium
Microsporum audouinii
Mycosel agar/Mycobiotic agar; microscopic examination: many microconidia smooth elongated, macroconidia few or absent; urea agar: positive in 2 days, star-shaped powdery colonies; round grape-like clusters of microconidia on cornmeal agar, few spiral hyphae, present in some cultures
T. mentagrophytes
Mycosel agar/Mycobiotic agar; microscopic examination: many microconidia smooth elongated, macroconidia few or absent; negative in 2 days; cornmeal dextrose agar; red pigment - tear-shaped microconidia along hyphae on cornmeal agar
Trichophyton rubrum
Mycosel agar/Mycobiotic agar; microscopic examination: many microconidia smooth elongated, macroconidia few or absent; urea agar = no red pigment; balloon-shaped microconidia on cornmeal agar - trichophyton agar 4 - increased growth
T. tonsurans
Mycosel agar/Mycobiotic agar; conidia usually not present, only hyphae seen; colony violet color - Trichophyton agar 4 - increased growth
Trichophyton violaceum
Mycosel agar/Mycobiotic agar; conidia usually not present, only hyphae seen; colony color white and wrinkled; antler hyphae present
T. schoenleinii
Mycosel agar/Mycobiotic agar; conidia usually not present, only hyphae seen; colony very slow growing, heaped up partially submerged in medium, smooth surface without aerial hyphae; increased growth at 37°C with production of chains of chlamydospores with septa appearing like fission planes; Trichophyton agar 4 increased growth
T. verrucosum