Superficial Mycoses Flashcards
• Elicit little or no host immune response
• Non-destructive, asymptomatic
• Usually of cosmetic concern
• Easy to diagnose and treat
SUPERFICIAL MYCOSES
• Fungi that colonize the keratinized outer layers ofthe skin (stratum corneum of the epidermis), hair, and nails.
SUPERFICIAL MYCOSES
Pityriasis versicolor
Seborrhoeic dermatitis including Dandruff and Follicular pityriasis
Malassezia spp.
(a lipophilic yeast)
Common
Tinea nigra
Hortaea werneckii
Rare
White piedra
Trichosporon spp.
Common
Black piedra
Piedraia hortae
Rare
• Discrete, serpentine, hyperpigmented or hypopigmented maculae or spots on the skin (chest, upper back, arms, or abdomen), enlarge and coalesce
PITYRIASIS VERSICOLOR or TINEA
VERSICOLOR
• Chronic and nonirritating superficial infection of the _______caused by Malassezia species
stratum corneum
• Mostly lipophilic yeasts, part of the skin flora;
opportunistic (folliculitis in immunosuppressed patients, occasionally onychomycosis, rarely catheter acquired fungemia in patients undergoing lipid replacement therapy)
Malassezia species
Increases where the climate is hot and humid and is highest in the tropics
Malassezia spp
Malassezia related infections:
pityriasis versicolor
seborrheic dermatitis
dandruff
atopic eczema
folliculitis
Malassezia species:
•___ species;___ are lipid dependent
14
Malassezia spp
- a facultative pathogenic yeast
- non-lipophilic, transmitted by dogs
- most commonly identified causative fungus(JDDG’S Mycology Update Report, 2014); followed by M. furfur & M. sympodialis
- contributor to seborrheic dermatitis (i.e. dandruff)
• M. furfur
• M. pachydermatis
• M. globosa
• M. restricta
• Affect all ages; annual incidence: 5-8%
• Predisposing factors: immune status, genetic factors, elevated temperature and humidity
MALASSEZIA INFECTIONS
Malassezia infection
• Treatment: Daily application (_____days) of ___________ treatment,
50%_______ 2x daily for 14 days.
10-14
selenium sulfide/zinc pyrithione or topical (lathering) imidazole
propylene glycol in water
Malassezia infection
Frequent relapse:….., (treatment)
prophylactic topical treatment once or twice a week is mandatory to prevent relapse
oral therapy with itraconazole (200mg/day, 5-7 days)
Malassezia spp
- Specimens:_______, in case of fungemia,______
skin scrapings of superficial lesions
blood/indwelling catheter tips
Malassezia
- Confirmed by ________microscopic examination of scrapings from infected skin
*_________ are observed.
direct KOH (w/ Parker Ink)
Short unbranched, nonpigmented hyphae and spherical yeast cells
- “spaghetti and meatballs appearance” of
Malassezia species
Diagnostic for
• Laboratory Diagnosis
Clusters of thick-walled round, budding yeast-like cells & short angular hyphal forms up to 8um in diameter (ave. 4um diam.)
M. furfur
Media for Malassezia
SDA-cycloheximide-Olive oil
Media for Malassezia
SDA-cycloheximide-Olive oil
Laboratory Diagnosis
- M. furfur is_____; in vitro growth stimulated by natural oils or other fatty substances
- Method: Overlay SDA-cycloheximide (actidione) with _____or use a special medium like______ which contains…
- Incubate at______
lipophilic
OLIVE OIL
Dixon’s agar (contains glycerol mono-oleate)
30C for 5-7 days
Malassezia
- SDA-C-Olive oil: morphology
Cream-colored to tan yeastlike colony composed of budding yeastlike cells; hyphae are infrequently produced (in culture)
T or F
Culture preparations are usually not necessary to diagnose pityriasis versicolor.
True
Tinea nigra
A superficial, chronic, and asymptomatic infection of the stratum corneum caused by the dematiaceous fungus,
________
Hortaea werneckii
Previous names of Hortaea werneckii
Phaeoannellomyces werneckii,
Exophiala werneckii
Ubiquitous saprophyte in nature;
Lesions: dark brown to black discoloration, often on the palms, non-scaling macules, no inflammatory reaction
Tinea nigra
• Brownish color darkest at the advancing periphery
• Resemble a faded silver nitrate stain
• May also resemble melanoma and other types of skin cancer
TINEA NIGRA
• CLINICAL INFECTION
• Usually consist of a solitary,
innocuous macule with sharply defined margins, which spreads by expansion; familial spread also reported
TINEA NIGRA
Tinea nigra
Tx:_______(benzoic acid compound), or an_____ agent twice a day for 3-4 weeks, keratolytic solutions, salicylic acid
Whitfield’s ointment
imidazole
TINEA NIGRA
• LAB Diagnosis
• Specimen: skin scrapings
• Direct microscopy: _______ and _____ or _______ or_____
(Pigmented hyphae/yeast forms are confined to the outer layers of the stratum corneum)
10% KOH and Parker ink or calcofluor white mounts
H&E
TINEA NIGRA
• Pigmented, brown-dark olivaceous (dematiaceous)
septate hyphae and 2-celled yeast cells producing_____
annelloconidia
TINEA NIGRA
Culture:
*Inoculate scrapings (periphery of lesions) onto________
White gray yeastlike becoming velvety from olive to black
Serology not required
SDA (+antibiotics)
Tinea nigra
*Final ID:
Clinical, microscopic and
culture features
BLACK PIEDRA
* A hard, nodular infection of the hair shaft caused by_______
Piedraia hortae.
- Hard black nodules on the shafts of the scalp, beard, moustache and pubic hair
Black piedra
Black piedra
- Tx:
shave or cut hair short, topical antifungal creams / ointment / shampoo, oral terbinafine
Black piedra: Piedraia hortae
• Clinical material:_______
• Direct microscopy:_______ and _____ or _______
epilated hairs with hard black nodules present on the shaft
10% KOH and Parker ink or calcofluor white
Black piedra
• Black nodules are made up of mass of stroma-like center (_______)
containing asci (8 ascospores, taper
towards both ends), septate hyphae
• Culture on SDA:____
• ID: characteristic clinical, microscopic, culture features
ascostromata
dark, brown-black colonies (25C; 2-3 weeks growth)
Black piedra: Piedraia hortae
• Treatment:_____
• In-vitro susceptibility tests show sensitivity to_____ (250mg a day for 6 weeks)
shave or cut hairs short
terbinafine
black piedra
• Colonies: _______
• From the reverse, the colony is_____ in color
slow growing, small, folded, velvety and dark brown to black in color.
• may produce a reddish brown diffusible pigment
black
Black piedra
• Microscopic: Dark, septate hyphae, intercalary_______-like cells
chlamydoconidium
WHITE PIEDRA
• Due to infection with______
Trichosporon species
White piedra
• Clinically show larger, softer, white or light brown nodules (______) of the hairs (axillary, pubic, beard, scalp hair); no pathological changes elicited
• 4 common species:…
1.0-1.5mm
T. asahii
T. asteroides
T. inkin
T. ovoides
• Trichosporon asahi (75%) - leukemia, solid tumors and AIDS.
• Common in young adults, cause opportunistic disseminated infections;
White piedra
White piedra
• Tx:
removal of infected hair, topical ointment, terbinafine
White piedra
Laboratory Diagnosis:
• Specimens: epilated hairs with_____ present on the shaft
• Direct microscopy:_____ and _____ or _____
• Look for irregular, soft, white or light brown nodules, 1.0-1.5 mm in length, firmly adhering to the hairs
white soft nodules
10% KOH and Parker ink/calcofluor white mounts
White piedra
*Laboratory Diagnosis:
• Culture: Hair fragments implanted on___
• Colonies:_____
SDA
white to yellowish to deep cream colored, smooth, wrinkled, velvety, dull colonies with a mycelial fringe
White piedra
• Microscopic:_____
• Final ID: characteristic clinical, microscopic and culture features
Septate hyphae, pseudohyphae, arthroconidia, branched hyphae, spherical/oval blastoconidia
WHITE PIEDRA
Management:
Shaving the hairs, topical imidazole agent to prevent reinfection
“spaghetti and meatballs” appearance in skin scrapings; yeasts/hyphae, lipophilic
Pityriasis versicolor
Malassezia species
Hypo- or hyper-pigmented macules
Pityriasis versicolor
Malassezia species
dematiaceous, 2-celled oval yeasts in skin scrapings
Tinea nigra
Hortaea werneckii
black macules
Tinea nigra
Hortaea werneckii
black nodule on hair shaft composed of spore sacs and spores (ascospores)
Black piedra
Piedraia hortae
Black, hard nodules on hair shaft
Black piedra
Piedraia hortae
white nodules on hair shaft composed of yeastlike cells; colonies - hyphae, arthrospores, pseudohyphae, blastoconidia
White piedra
Trichosporon species
White or cream-colored, soft nodules on hair shaft
White piedra
Trichosporon species
