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Superficial Mycoses Flashcards

(59 cards)

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1
Q

• Elicit little or no host immune response
• Non-destructive, asymptomatic
• Usually of cosmetic concern
• Easy to diagnose and treat

A

SUPERFICIAL MYCOSES

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2
Q

• Fungi that colonize the keratinized outer layers ofthe skin (stratum corneum of the epidermis), hair, and nails.

A

SUPERFICIAL MYCOSES

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3
Q

Pityriasis versicolor

Seborrhoeic dermatitis including Dandruff and Follicular pityriasis

A

Malassezia spp.
(a lipophilic yeast)

Common

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4
Q

Tinea nigra

A

Hortaea werneckii

Rare

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5
Q

White piedra

A

Trichosporon spp.

Common

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6
Q

Black piedra

A

Piedraia hortae

Rare

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7
Q

• Discrete, serpentine, hyperpigmented or hypopigmented maculae or spots on the skin (chest, upper back, arms, or abdomen), enlarge and coalesce

A

PITYRIASIS VERSICOLOR or TINEA
VERSICOLOR

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8
Q

• Chronic and nonirritating superficial infection of the _______caused by Malassezia species

A

stratum corneum

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9
Q

• 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)

A

Malassezia species

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10
Q

Increases where the climate is hot and humid and is highest in the tropics

A

Malassezia spp

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11
Q

Malassezia related infections:

A

pityriasis versicolor
seborrheic dermatitis
dandruff
atopic eczema
folliculitis

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12
Q

Malassezia species:
•___ species;___ are lipid dependent

A

14

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13
Q

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)
A

• M. furfur

• M. pachydermatis

• M. globosa

• M. restricta

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14
Q

• Affect all ages; annual incidence: 5-8%

• Predisposing factors: immune status, genetic factors, elevated temperature and humidity

A

MALASSEZIA INFECTIONS

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15
Q

Malassezia infection

• Treatment: Daily application (_____days) of ___________ treatment,

50%_______ 2x daily for 14 days.

A

10-14

selenium sulfide/zinc pyrithione or topical (lathering) imidazole

propylene glycol in water

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16
Q

Malassezia infection

Frequent relapse:….., (treatment)

prophylactic topical treatment once or twice a week is mandatory to prevent relapse

A

oral therapy with itraconazole (200mg/day, 5-7 days)

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17
Q

Malassezia spp

  • Specimens:_______, in case of fungemia,______
A

skin scrapings of superficial lesions

blood/indwelling catheter tips

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18
Q

Malassezia

  • Confirmed by ________microscopic examination of scrapings from infected skin
    *_________ are observed.
A

direct KOH (w/ Parker Ink)

Short unbranched, nonpigmented hyphae and spherical yeast cells

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19
Q
  • “spaghetti and meatballs appearance” of
A

Malassezia species

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20
Q

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.)

A

M. furfur

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21
Q

Media for Malassezia

A

SDA-cycloheximide-Olive oil

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22
Q

Media for Malassezia

A

SDA-cycloheximide-Olive oil

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23
Q

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______
A

lipophilic

OLIVE OIL

Dixon’s agar (contains glycerol mono-oleate)

30C for 5-7 days

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24
Q

Malassezia

  • SDA-C-Olive oil: morphology
Study These Flashcards
A

Cream-colored to tan yeastlike colony composed of budding yeastlike cells; hyphae are infrequently produced (in culture)

25
T or F Culture preparations are usually not necessary to diagnose pityriasis versicolor.
True
26
Tinea nigra A superficial, chronic, and asymptomatic infection of the stratum corneum caused by the dematiaceous fungus, ________
Hortaea werneckii
27
Previous names of Hortaea werneckii
Phaeoannellomyces werneckii, Exophiala werneckii
28
Ubiquitous saprophyte in nature; Lesions: dark brown to black discoloration, often on the palms, non-scaling macules, no inflammatory reaction
Tinea nigra
29
• 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
30
• CLINICAL INFECTION • Usually consist of a solitary, innocuous macule with sharply defined margins, which spreads by expansion; familial spread also reported
TINEA NIGRA
31
Tinea nigra Tx:_______(benzoic acid compound), or an_____ agent twice a day for 3-4 weeks, keratolytic solutions, salicylic acid
Whitfield's ointment imidazole
32
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
33
TINEA NIGRA • Pigmented, brown-dark olivaceous (dematiaceous) septate hyphae and 2-celled yeast cells producing_____
annelloconidia
34
TINEA NIGRA Culture: *Inoculate scrapings (periphery of lesions) onto________ White gray yeastlike becoming velvety from olive to black Serology not required
SDA (+antibiotics)
35
Tinea nigra *Final ID:
Clinical, microscopic and culture features
36
BLACK PIEDRA * A hard, nodular infection of the hair shaft caused by_______
Piedraia hortae.
37
* Hard black nodules on the shafts of the scalp, beard, moustache and pubic hair
Black piedra
38
Black piedra * Tx:
shave or cut hair short, topical antifungal creams / ointment / shampoo, oral terbinafine
39
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
40
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)
41
Black piedra: Piedraia hortae • Treatment:_____ • In-vitro susceptibility tests show sensitivity to_____ (250mg a day for 6 weeks)
shave or cut hairs short terbinafine
42
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
43
Black piedra • Microscopic: Dark, septate hyphae, intercalary_______-like cells
chlamydoconidium
44
WHITE PIEDRA • Due to infection with______
Trichosporon species
45
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
46
• Trichosporon asahi (75%) - leukemia, solid tumors and AIDS. • Common in young adults, cause opportunistic disseminated infections;
White piedra
47
White piedra • Tx:
removal of infected hair, topical ointment, terbinafine
48
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
49
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
50
White piedra • Microscopic:_____ • Final ID: characteristic clinical, microscopic and culture features
Septate hyphae, pseudohyphae, arthroconidia, branched hyphae, spherical/oval blastoconidia
51
WHITE PIEDRA Management:
Shaving the hairs, topical imidazole agent to prevent reinfection
52
"spaghetti and meatballs" appearance in skin scrapings; yeasts/hyphae, lipophilic
Pityriasis versicolor Malassezia species
53
Hypo- or hyper-pigmented macules
Pityriasis versicolor Malassezia species
54
dematiaceous, 2-celled oval yeasts in skin scrapings
Tinea nigra Hortaea werneckii
55
black macules
Tinea nigra Hortaea werneckii
56
black nodule on hair shaft composed of spore sacs and spores (ascospores)
Black piedra Piedraia hortae
57
Black, hard nodules on hair shaft
Black piedra Piedraia hortae
58
white nodules on hair shaft composed of yeastlike cells; colonies - hyphae, arthrospores, pseudohyphae, blastoconidia
White piedra Trichosporon species
59
White or cream-colored, soft nodules on hair shaft
White piedra Trichosporon species

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