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Unit 3 Microbio > L23: Dermatomycoses > Flashcards

L23: Dermatomycoses Flashcards

1
Q

Cutaneous fungi (2)

A

Malassezia furfur

Hortaea werneckii

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2
Q

Dermatophytes (3)

A

Trichophyton
Microsporum
Epidermophyton

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3
Q

Environmental dermatophytes with sexual spores (2)

A

Microsporum

Trichophyton

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4
Q

Characteristics of dermatophytes

A

pathogenic fungi that require keratin for growth
do not infect mucosal surfaces
secrete keratinase

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5
Q

infective stage of dermatophytes

A

arthroconidium: spores

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6
Q

infected hairs exhibit fluorescence

A

ceratin species of microsporum

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7
Q

Visualize ______ in dead keratinized tissue to diagnose dermatophytes

A

hyphae

arthoconidia

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8
Q

Lab culture of dermatophytes

A

material under nails

sabouraud agar at room temperature 1-3 weeks

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9
Q

Dermatophyte test medium

A

allows for early detection: 3 days

fermentation of nitrogenous compounds preferred over carbohydrates: color change (alkaline pH): differential

Selective: cyclohexamide and abx

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10
Q

Identify trichophytin:

A

Galactomannan peptide
Crude antigen of dermatophytes
-CHO component: immediate response
-Peptide component: delayed response

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11
Q

10% potassium hydroxide

A

KOH

digests human tissue, leaves fungal components intact

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12
Q

Zoophilic

A

animal pathogens that may be transmitted to people

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13
Q

Antrophophilic

A

human transmission

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14
Q

geophilic

A

transmitted through soil to people

usually invade non-viable keratinized tissue

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15
Q

Where are dermatophytes most prevalent?

A

tropics

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16
Q

What do dermatophyte lesions look like?

A

Inflammed at edges, central clearing zone

hair loss with itching

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17
Q

Predisposed to dermatophyte infection

A

Nail trauma
HIV
DM
Immunosuppressive meds

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18
Q

Risk factors for dermatophyte infection

A

Communal bathing facilities
Immunocompromised
Cushing syndrome (increased cortisol interferes with inflammation)
Contact sports

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19
Q

Disseminated dermatophyte infection in HIV patients (2)`

A

T mentagrophytes

M canis

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20
Q

Arthrospores

A

fragment hyphal elements in hair, nails, outer skin
disseminate from one host to another (person-to-person)
survive in environment

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21
Q

Besides arthrospores, other ways to get a dermatophyte infection

A

micronidia (asexual spore)
macronidia (multicellular asexual spore)
sexual spores

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22
Q

Id reaction

A

allergic dermal reaction to fungal antigens occurring in areas devoid of organisms
most common in tinea pedis
sometimes a result of excessive treatments or pruritus

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23
Q

Id reaction treatment

A

treated as an allergy:
corticosteroids, antihistamines (systemic or topical)
wet compresses

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24
Q

what are spores susceptible to?

A

common disinfectants, chlorine, bleach, detergents

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25
3 Trichophyton species
technically there are "5 major clinically relevant species" * T mentagrophytes* * T tonsurans* * T rubrum*
26
Do trichophyton species fluoresce?
Not often
27
Trichophyton macroconidia
pencil shaped, thin walls
28
Trichphyton produce
spindle shaped hyphae microconidia macroconidia
29
Most common cause of tinea capitis
Microsporum species
30
Do microsporum fluoresce?
Yes, under a wood's lamp
31
Microsporum produce
Hyphae Microconidia Large, spindle shaped, thick walled, mulitcellular Macroconidia
32
Tinea unguium aka
onychomycosis | nails
33
Tinea cruris
jock itch | groin
34
Most common causes to tinea capitis (3)
M canis T metagrophytes T tonsuranx
35
Tinea capitis: trichophyton
endothrix | Insidee the hair follicle, causes alopecia
36
Tinea capitis:microsporum
ectothrix | outside surface of the hair
37
zoonotic tinea capitis
comes from puppies and kittens
38
black dot ringworm
comes from broken follicles appearing as black dots
39
most prevalents dermatophytoses
tinea pedis
40
Predisposing factors to tinea corporus/cruris
DM obesity excessive perspiration
41
Transmission of tinea corporus/cruris is both ____
direct | indirect: contact with objects: towels, clothing, bed linens
42
For onychomycosis, treatment requires
systemic antifungals | culture: often candida
43
what is tinea unguium sometimes mistaken for?
psoriasis
44
Is candida a dermatophyte?
NO | It is a mycoses
45
Most common opportunistic mycoses worldwide
candida species
46
A parent yeast cell of candida can take on 3 different morphologies:
1. Budding yeast 2. Pseudohypha 3. Germ tube - germ tube can differentiate into hyphae
47
The most adhesive candida morphology
Germ tube
48
Does candida have a lot a virulence factors?
NO | but all species are capable of attachment
49
Whatcha gonna see on direct microscopic examination of candida?
Large "G+" cells Yeast cells Pseudohyphae True hyphae
50
Cultures for candida
Chromagar | Germ tubes: incubate in serum for 3 hours at 37 C
51
Serology for candida
difficult, as it's normal flora and a pt may have had prior exposure low titers of antibody
52
Tinea versicolor aka
malassezia furfur
53
malassezia furfur morphology (under a microscope+KOH)
short unbranched hyphae + spherical cells = "spaghetti and meatballs"
54
Liphilic growth factor
means it needs fat to grow- sebaceous glands | malassezia furfur
55
malassezia furfur is most common in
tropics | young adults
56
malassezia furfur appears as
depigmented or hyperpigmented skin may enlarge +/- dandruff
57
Tinea negra aka
hortaea werneckii
58
extreme halotolerant
hortaea werneckii
59
hortaea werneckii morphology
dimorphic: can grow as yeast or mold
60
hortaea werneckii looks like
a brownish lesion: produces melanin

Unit 3 Microbio (13 decks)

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