6 cutaneus myco
Post on 27-May-2015
2.312 Views
Preview:
TRANSCRIPT
Superficial Mycoses
Causative agents:
Malassezia furfurExophiala werneckiiTrichosporon beigelii Piedraia hortae
Cutaneous mycoses (Dermatophytoses)
fungal infections involving the dermis and its appendages
(hair follicles and nails)
o Dermatomycosis - more general name for any skin disease caused by a fungus.
o Dermatophytosis – mycotic infection of the nails, hair, and/or stratum corneum of the skin caused by dermatophytes.
o Generally called “Ringworms” or o “Tineas” (Latin for ringworms)
Dermatophytes are keratinophilicAll produce septate, hyaline hyphae Infection:
Colonization of the skinSpreads in a centrifugal pattern forming a
ringAffected area varies from patchy scaling to a
toxic eczema-like reaction
Dermatophytoses
Severity depends on
(1) strains or species of fungus involved (2) sensitivity of the host to a particular pathogenic fungus.
More severe reactions occur when a dermatophyte crosses non-host lines.
Dermatophytoses
Major sources of ringworm infection
Schools, military camps, prisons.
Warm damp areas (e.g., tropics, moisture accumulation in clothing and shoes).
Animals (e.g., dogs, cats, cattle, poultry, etc.).
Geophilic species - e.g., M. gypseum,
T. ajelloi
Zoophilic species - e.g., M. canis, T. verrucosum
Anthropophilic species - e.g., M. audounii, T.
tonsurans)
Dermatophytes
a. Microsporum
- skin, hair (scalp)
- children, rarely in adults
- spontaneous remission
b. Epidermophyton
- skin, nails
c. Trichophyton
- hair (scalp), skin & nails
- chronic
Skin:Tinea corporis Tinea crurisTinea manuum Tinea pedisTinea fascie Tinea imbricata
Hairy areas:Tinea capitis Tinea barbae
Nail:Tinea unguium/ onychomycosis
Tineas
Tinea corporis
Ringworm of the body (Generally restricted to stratum corneum of the smooth skin)
Reddened, circular scaly patch with sharp delineated margins (may developing vesicles and postules)
EA: Trichophyton rubrum
Trichophyton mentagrophytes
Tinea corporis
Tinea corporis – body ringworm
Tinea corporis
MOT: direct contact; fomites; autoinnoculation
normally resolves itself in several months. (T. rubrum – relapse)
TX: topical agent containing tolnaftate, ketoconazole, miconazole.
Tinea corporis
vigorous treatment including cleaning of area to remove scales and fungicidal topical applications of ammoniated mercury ointment, 3 % salicylic and sulfuric acid, or tincture of iodine for several weeks.
Widespread tinea corporis and more severe lesions: systemic griseofulvin treatment (about 6 weeks for effective treatment).
Tinea cruris
Ringworm of the groin
Almost exclusively in men
Lesion resemble tinea corporis
Often starts on the scrotum and spread to the groin as dry, itchy lesions
Tinea cruris (“jock itch”)
Tinea cruris
EA: Trichophyton rubrum
Epidermophyton floccosum (usually associated with epidemics)
MOT: Sharing of linens, towels or clothes (Athletes, soldiers, ship crews)
Predisposing factors: persistent perspiration, irritation of skin from clothes, or other pre-existing diseases.
Diagnosis KOH and Culture of dermatophyte from
skin scrapings. If lesion "weep", it is likely caused by a
yeast, such as, Candida albicans Treatment
Tolnaftate Area is sensitive
Tinea cruris
Tinea pedis
Ringworm of the soles and interdigital areas
men & women are equally affected
More common in adults
Peeling, maceration and fissuring of the skin to fluid-filled vesicles and bullae.
Tinea pedis
Tinea Pedis – Athlete’s Foot Infection
Tinea pedis
All forms are pruritic
EA: T. rubrum (chronic infections)
E. floccosum (acute & spontaneously resolves)
Tinea manuum
Ringworm of the palms and interdigits
Common among patients with tinea pedis
Symptoms generally resemble that of tinea pedis
EA: T. rubrum & T. mentagrophytes
E. floccosum
Tinea manunm
Dermatophytid Reaction
Tinea barbae
Ringworm of the bearded areas of the neck
postular folliculitis
Common among men who work with cattles
EA: T. verrucosum &
T. mentagrophytes
Tinea barbae
Kerions : boggy inflammation/spongy swelling
Alopecia is also common in untreated infections
Tinea barbae
Tinea fascie
Two forms of T. unguium:
Leukonychia mycotica /superficial white onychomycosis - invasion of fungus restricted on patches or pits on surface of the toenail.
Invasive subungual dermatophytosis - lateral or distal edges first involved, followed by invasion of nail plates by dermatophytes.
Tinea unguium
Most commonly caused by T. rubrum, then E. floccosum or otherTrichophyton spp.
Resistant to treatment Rarely resolves spontaneously.
Tinea unguium
Tinea unguium
Tinea Unguium
Tinea capitis
Ringworm of the scalp, eyebrows and eyelashes
Fungus grows into hair follicle and hair shaft
Caused by species of Microsporum and
Trichophyton.
Tinea capitis
Wood's lamp
Subculture any strands of hair that fluoresce
Tinea capitis
Tinea capitis
Ectothrix infection - fragmentation of mycelium into conidia around the hair
shaft or just beneath the cuticle.
Tinea capitis
Caused by M. audouinii, M. canis, M. ferrugineum, T. mentagrophytes, T. verrucosum and T. megninii.
Tinea capitis
“gray patch T. capitis"
ectothrix disease common in children usually not associated with inflammation.
Tinea capitis
Endothrix infection - arthroconidia formation within the hair shaft.
caused by T. tonsurans , T. violaceum, T. rubrum, and T. gourvillii.
Tinea capitis
“Black-dot T. capitis”
Formed as the hair continues to grow, as the conidia in the shafts of the hair appear as black dots
Tinea Capitis
Tinea favosa (favus)
ringworm infection of the scalp (crusty hair)
Characterized by the occurrence of dense masses of mycelium and epithelial debris, which forms yellowish, cup-shaped crusts.
Tinea favosa (favus)
Leads to scarring and alopecia
“mousy odor”
Caused by T. schoenleinii
Diagnosis of Dermatophytoses
Note the symptoms.
Note the kind of tissue attacked
Observe proper collection of the specimen
Keep specimen dry during transport
Microscopic examination of slides of skin scrapings, nail scrapings, and hair.
Methods:
1. Direct MicroscopyNot sensitiveUseful in more severe conditions
KOH (10% & 20%)
2. Culture
Observe type of colonies
Pigment production: one pigment on the surface of the colony, and another pigment other than black, on the reverse
Emmon’s modification of Sabouraud Dextrose Agar (SDA); or SDA with 4% glucose
incorporate chloramphenicol or gentamicin and cycloheximide
thiamine will enhance growth of dermatophytes esp. Trichophyton verrucosum (Nutritional Studies)
Dermatophyte Test medium (DTM) screening medium (w/ phenol red)
Microsporum species
Microsporum gypseum
Microsporum canis
Microsporum species
Common features:Colony:
Mycelium: white to buffUnderside: yellow to reddish brown
Microsporum gypseum
Colonies are at first white and downy, later become flat and granular with white sterile hyphae at the center
Surface pigment is tan to cinnamon –pink to brown
Reverse is tan to orange-brown or modified cinnamon-pink on PDA
Microsporum gypseum
Macronidia: Ellipsoidal to fusiform with thick, rough walls
Microconidia: Sessile and solitary
Wood’s lamp: Dull-green yellow
Microsporum canis
Macroconidia: Spindle shaped with asymmetrical beaked apex and thick rough walls
Microconidia: Clavate or pyriform
Microsporum canisTeleomorph: Arthroderma otaeMicrosporum canis
Teleomorph: Arthroderma otae
Wood’s lamp: Bright yellow-green Colonies: Yellow pigment on reverse
Epidermophyton species
Epidermophyton floccosum
Tinea unguium, tinea cruris, pedis
Epidermophyton floccosum
Colony:Center of colony may be foldedMycelium: mustard yellow or “khaki”;
suede, gentle folds; slow growerUnderside: yellow-brown or yellow
orange
Epidermophyton floccosumMicroscopic:
attached in multiples (2 – 4/group)Macroconidia = moderately thick , smooth walls
(beaver tails) or paddle-likeClubbed-shaped, 2 – 5 cell macroconidiaSeptate,hyaline hyphae
Epidermophyton floccosum
Microscopic:
Presence of macroconidia in cultures varies and may not help in identification of cultures.
Most common species include: Trichophyton mentagrophytes T. rubrum T. tonsurans T. verrucosum T. violaceum T. schoenleinii T. ajelloi (rare infects humans).
Trichophyton species
Most common dermatophyte on humans and animals.
Microconidia: en grappe
Trichophyton mentagrophytes
Macroconidia: when present, are cigar-shaped.
Spiral hyphae
Trichophyton mentagrophytes
Colony: Texture: deep, cottony; white and downy; pale yellow to tan reverse
Trichophyton mentagrophytes
Trichophyton mentagrophytes
Resistant and persistent
Microconidium: clavate or "teardrop" shape with a broad attachment point of the hyphae.
may develop on sides of macroconidium.
Trichophyton rubrum
Trichophyton rubrum
Colony: fluffy white with Port burgundy wine or venous blood underside. When
intensely pigmented in culture the color is reminiscent
Trichophyton rubrum
Anthropophilic; third most common cause of tinea capitis
Macroconidia: Short blunt , irregular clubs with moderately thick, smooth walls
Microconidia: Truncate of varying shapes; typically numerous
Hyphae are hyaline, septate and often with terminal swellings
Trichophyton tonsurans
Colony: Usually flat and off-white to yellow initially with a powdery texture; wrinkled
Reverse on SDA is yellow-brown to reddish brown
Growth is enhanced by thiamine and inositol.
Trichophyton tonsurans
Associated with cattle ("barn itch")
Causes severe infections in humans on the scalp and beard.
Trichophyton verrucosum
Colony: no pigment to yellow on reverse.
On unenriched media
chains of chlamydoconidia and antler-like hyphae.
On thiamine-enriched media,
produces many small microconidia and occasionally macroconidia
Trichophyton verrucosum
Trichophyton verrucosum
http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Dermatophytes/Trichophyton/verrucosum.html
Endothrix infection of hair.
Trichophyton schoenleinii
Colony: waxy to suede-like; off white in color.
Colony may become convoluted from folds that develop
No conidia (micro- or macro-) even on enriched media .
Trichophyton schoenleinii
top related