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Mycology & Virology > Superficial fungi > Flashcards

Superficial fungi Flashcards

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1
Q

Four superficial fungi

A

i. Hortaea werneckii
ii. Malassezia furfur
iii. Piedraia hortae
iv. Trichosporon ovoides

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2
Q

Halophilic species that live in seawater, mollusks, and other saline habitats

A

Hortaea werneckii

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3
Q

Hortaea werneckii is causative agent of

A

tinea nigra

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4
Q

other terms for tinea nigra

A

tinea nigra palmaris
keratomycosis nigricans

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5
Q

Hortaea werneckii are member of what species

A

black yeasts-like species containing a wide hyphae that
become profusely septate during growth

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6
Q

have annellidic conidiogenesis from broad scars.

A

Hortaea werneckii

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7
Q

describe lesions of tinea nigra

A

flat, smooth, not scaly, and appear as irregularly shaped brown
to black spots resembling silver nitrate stains

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8
Q

The palmar and plantar lesions (stratum corneum) of tinea nigra may also resemble

A

melanoma

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9
Q

laboratory diagnosis of Hortaea werneckii

A

Skin scrapings from dark pigmented lesions.

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10
Q

growth rate of Hortaea werneckii

A

Slow grower (matures within 21 days)

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11
Q

colony morphology of Hortaea werneckii in SDA

A

1st:
light colored
moist to mucoid
shiny
yeast-like
2nd- 3rd week
become olive-black, grayish green hyphae in periphery, may lose shine due to to thin layer of mycelium

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12
Q

reverse colony morphology of Hortaea werneckii in SDA

A

black

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13
Q

Wood’s lamp: Hortaea werneckii

A

no fluorescence

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14
Q

round at one end while tapered and elongated with striations at the end where conidia are formed

A

anellides

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15
Q

Hortaea werneckii mature forms are:

A

two-celled

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16
Q

Hortaea werneckii develop this as they age

A

dark, closely septated, thick-walled hyphae
Chlamydoconidia

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17
Q

contains 15 lipid-dependent species that are widely distributed in humans and other animals

A

Genus Malassezia

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18
Q

synonyms of Malassezia furfur

A

Pityrosporum furfur
Pityrosporum ovale pro parte

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19
Q

Differentiation of Malassezia spp. require

A

molecular sequencing

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20
Q

most clinical laboratories prefer to report results of Malassezia spp. as

A

Malassezia furfur species complex
Malassezia species

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21
Q

The most common species of Malassezia

A

M. furfur

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22
Q

common Malassezia spp which is non-lipid dependent, frequent
colonizer of canine auditory canals and linked to systemic Malassezia infections in neonates.

A

M. pachydermatis

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23
Q

Two Malasseia spp that are virtually omnipresent on human skin.

A

M. globosa
M. obtusa

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24
Q

the main causative agents of the skin infection pityriasis versicolor.

A

M. furfur
M. sympodialis
M. globosa
M. slooffiae

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25
tinea versicolor tissue reaction
lesion that appear as scaly (furfuraceous), discrete, or concrescent, hypopigmented ,and(or) mild to moderate hyperkeratosis
26
dermatological disease caused by Malassezia spp in patients with AIDS
seborrheic dermatitis
27
Malassezia also causes this diseases in in patients receiving prolonged infusion of lipid formulation through contaminated central venous catheters.
fungemia and occ. systemic infection
28
predisposing factors to Malassezia diseases
poor nutrition excessive sweating pregnancy
29
Laboratory diagnosis of M. furfur species complex
Skin scrapings from discolored area, blood, or tissue
30
growth rate of Malassezia furfur
Rapid; mature in 5 days
31
temperature preference of M. furfur
30-35oC grow poorly at 25oC
32
culture media of Malassezia furfur
SDA cycloheximide olive or vegetable oil
33
obverse colony morphology of M. furfur
Smooth, cream to yellowish brown, often becomes dry, dull, brittle, and wrinkled with age.
34
M. furfur scrapings may also be inoculated on
Leeming Notman medium
35
Wood's lamp: M. furfur
Fluoresces yellow-green with black
36
black spots in colonial morphology occur due to Malassezia’s production of this tryptophan derivative.
pityrialactone
37
M. furfur species complex filaments with budding yeast cells resemble:
“spaghetti & meatball” appearance
38
budding of M. furfur is
phialidic & unipolar
39
Found mostly in tropical regions in Africa, Asia, and Central and South America and infects humans as well as other primates
Piedraia hortae
40
Piedraia hortae is the etiologic agent of
black piedra
41
black piedra infects these sites
scalp hair beard or mosutache axillary or pubic hairs
42
black piedra is characterized by
discrete, hard, gritty, dark brown to black nodules adhering firmly to the hair shaft.
43
affected by black piedra nodules and become weak and often break at the point of infection
hair shaft
44
specimen for laboratory diagnosis of Piedraia hortae
Hair fragments containing one or more black nodules, collected by clipping or by plucking
45
growth rate of Piedraia hortae
Slow growth; mature in 21 days
46
Piedraia hortae is inoculated in
SDA with chloramphenicol and cycloheximide
47
added to Piedraia hortae medium to increase mycelial production
thiamine
48
Piedraia hortae colonial morphology
small, adherent, compact, somewhat raised, and dark greenish brown to black may be glabrous or covered with very short aerial hyphae.
49
colonial morphology of the reverse of Piedraia hortae
black
50
Piedraia hortae hyphae
Hyphae are closely septate, dark, and thick walled and vary in diameter; with many intercalary chlamydoconidia- like cells. Asci may be produced in culture.
51
Piedraia hortae asci
The walls of the asci readily dissolve, releasing single- celled, curved ascospores (5-10 x 30-35μm) that taper at the ends to form whip-like extensions.
52
Causes scalp hair white piedra
Trichosporon ovoides
53
T. asahii
cause of summer-type hypersensitivity in Japan.
54
CALAS assay
Cryptococcal Antigen Latex Agglutination System
55
share antigenicity with the capsular polysaccharide of C. neoformans
T. asahii
56
Trichosporon species present in hair
T. ovoides
57
Systemic- only Trichosporon species
T. asahii T. mucoides
58
Trichosporon species present in systemic, pubic hair and skin
T. inkin
59
Trichosporon species present only in axilla and rarely in skin
T. cutaneum
60
Trichosporon species present rarely in systemic and skin
T. asteroides
61
specimen for laboratory diagnosis of Trichosporon species
Hair fragments containing the adherent nodules
62
growth rate of Trichosporon species
Moderately rapid; mature in 5-7 days
63
culture media of Trichosporon species
SDA + chloramphenicol
64
colonial morphology of Trichosporon species
Yeastlike; at first cream colored, moist, and soft. The surface may become irregularly wrinkled, rather powdery or crumblike; the center may become heaped, and the colony may adhere to, and crack, the agar. The color often darkens to yellowish gray.
65
The squashed nodule reveals an intertwined hyaline septate hyphae, hyphae breaking up into oval or rectangular arthroconidia of 2-4μm
Trichosporon species
66
differentiates Trichosporon from Geotrichum spp.
presence of pseudohyphae and blastoconidia
67
urease test of trichosporon species
positive
68
All trichosporon can grow at 37 C except
T. cutaneum
69
Assimilation of T. asahii
arabinose
70
Assimilation of T. mucoides
inositol, arabinose, sorbitol
71
Assimilation of T. cutaneum
Inositol Arabinose Sorbitol
72
Assimilation of T. inkin
inositol
73
assimilation of T. ovoides
none (variable arabinose)

Mycology & Virology (10 decks)

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