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Mycology & Virology > Superficial fungi > Flashcards

Superficial fungi Flashcards

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
Q

tinea versicolor tissue reaction

A

lesion that appear as scaly (furfuraceous), discrete, or concrescent,
hypopigmented ,and(or) mild to moderate hyperkeratosis

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26
Q

dermatological disease caused by Malassezia spp in patients with AIDS

A

seborrheic dermatitis

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27
Q

Malassezia also causes this diseases in in patients receiving prolonged infusion of lipid formulation through contaminated central venous catheters.

A

fungemia and occ. systemic infection

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28
Q

predisposing factors to Malassezia diseases

A

poor nutrition
excessive sweating
pregnancy

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29
Q

Laboratory diagnosis of M. furfur species complex

A

Skin scrapings from discolored area, blood, or tissue

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30
Q

growth rate of Malassezia furfur

A

Rapid; mature in 5 days

31
Q

temperature preference of M. furfur

A

30-35oC
grow poorly at 25oC

32
Q

culture media of Malassezia furfur

A

SDA
cycloheximide
olive or vegetable oil

33
Q

obverse colony morphology of M. furfur

A

Smooth, cream to yellowish brown, often becomes dry, dull, brittle,
and wrinkled with age.

34
Q

M. furfur scrapings may also be inoculated on

A

Leeming
Notman medium

35
Q

Wood’s lamp: M. furfur

A

Fluoresces yellow-green with black

36
Q

black spots in colonial morphology occur due to Malassezia’s production
of this tryptophan derivative.

A

pityrialactone

37
Q

M. furfur species complex filaments with budding yeast cells resemble:

A

“spaghetti & meatball” appearance

38
Q

budding of M. furfur is

A

phialidic & unipolar

39
Q

Found mostly in tropical regions in Africa, Asia, and Central and South America and infects humans as well as other primates

A

Piedraia hortae

40
Q

Piedraia hortae is the etiologic agent of

A

black piedra

41
Q

black piedra infects these sites

A

scalp hair
beard or mosutache
axillary or pubic hairs

42
Q

black piedra is characterized by

A

discrete, hard, gritty, dark brown to black nodules
adhering firmly to the hair shaft.

43
Q

affected by black piedra nodules and become weak and often break at
the point of infection

A

hair shaft

44
Q

specimen for laboratory diagnosis of Piedraia hortae

A

Hair fragments containing one or more black nodules, collected by clipping or by plucking

45
Q

growth rate of Piedraia hortae

A

Slow growth; mature in 21 days

46
Q

Piedraia hortae is inoculated in

A

SDA with chloramphenicol and cycloheximide

47
Q

added to Piedraia hortae medium to increase mycelial production

A

thiamine

48
Q

Piedraia hortae colonial morphology

A

small, adherent, compact, somewhat raised, and dark greenish brown
to black
may be glabrous or covered with very short aerial hyphae.

49
Q

colonial morphology of the reverse of Piedraia hortae

A

black

50
Q

Piedraia hortae hyphae

A

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
Q

Piedraia hortae asci

A

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
Q

Causes scalp hair white piedra

A

Trichosporon ovoides

53
Q

T. asahii

A

cause of summer-type hypersensitivity in Japan.

54
Q

CALAS assay

A

Cryptococcal Antigen Latex Agglutination System

55
Q

share antigenicity with the capsular polysaccharide of C. neoformans

A

T. asahii

56
Q

Trichosporon species present in hair

A

T. ovoides

57
Q

Systemic- only Trichosporon species

A

T. asahii
T. mucoides

58
Q

Trichosporon species present in systemic, pubic hair and skin

A

T. inkin

59
Q

Trichosporon species present only in axilla and rarely in skin

A

T. cutaneum

60
Q

Trichosporon species present rarely in systemic and skin

A

T. asteroides

61
Q

specimen for laboratory diagnosis of Trichosporon species

A

Hair fragments containing the adherent nodules

62
Q

growth rate of Trichosporon species

A

Moderately rapid; mature in 5-7 days

63
Q

culture media of Trichosporon species

A

SDA + chloramphenicol

64
Q

colonial morphology of Trichosporon species

A

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
Q

The squashed nodule reveals an intertwined hyaline
septate hyphae, hyphae breaking up into oval or
rectangular arthroconidia of 2-4μm

A

Trichosporon species

66
Q

differentiates Trichosporon from Geotrichum spp.

A

presence of pseudohyphae and blastoconidia

67
Q

urease test of trichosporon species

A

positive

68
Q

All trichosporon can grow at 37 C except

A

T. cutaneum

69
Q

Assimilation of T. asahii

A

arabinose

70
Q

Assimilation of T. mucoides

A

inositol, arabinose, sorbitol

71
Q

Assimilation of T. cutaneum

A

Inositol Arabinose Sorbitol

72
Q

Assimilation of T. inkin

A

inositol

73
Q

assimilation of T. ovoides

A

none (variable arabinose)

Mycology & Virology (10 decks)

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