Fungi Flashcards

1
Q

What is the unicellular growth form of fungi? how do they reproduce?

A

yeast- budding

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2
Q

What is it called when yeast cell buds do not separate

A

pseudohyphae

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3
Q

What are hyphae

A

threadlike branching, cylindrical tubules of fungal cells attached end by end

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4
Q

What are molds

A

mycelia
multicellular colonies of clumped hyphae
produce spores

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5
Q

what are dimorphic fungi

A

fungi that grow as either yeast or mold depending on environment and temperature

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6
Q

What are Saprophytes

A

fungi that live in and utilize organic matter as energy source

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7
Q

Describe the innermost layer of fungi

A

cell membrane that is bilayer and has lots of sterols- ergosterol

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8
Q

How do most antifungals work

A

disrupting ergosterol
like amphotericin B and nystatin
or ergosterol syntehsis- azoles

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9
Q

What component of fungi are strong Ag to human immune system

A

the Cell wall

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10
Q

What stain do you use to visualize the capsule of fungi

A

India ink stain

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11
Q

What are the superficial fungal infections

A

pityriasis versicolor and tinea nigra

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12
Q

what is presentation of pityriasis versicolor

A

hypo and hyper pigmented patches on the skin

caused by Malassezia furfur

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13
Q

What is the presentation of tinea nigra

A

causes dark brown black painless patches on soles of hands and feet
caused by exophiala werneckii

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14
Q

How do you Dx tinea nigra or pityriasis versicolor

A

skins crapings mied with KOH will reveal hyphae and spherical yeast

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15
Q

What is the best Tx for superficial fungal diseases

A

dandruff shampoo that has selenium sulfate

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16
Q

what fungi cause cutaneous fungal infections

A

dermatophytes

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17
Q

What enzyme do dermatophytes secrete

A

keratinase

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18
Q

What are the most common dermatophytes

A

Microsporum, Trichophyton and Epidermophyton

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19
Q

presentation of tinea corporis

A

ring with red raised border
areas of active inflammation and area of healing in middle
ring worm

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20
Q

What is tinea cruris

A

jock itch

itchy red patches on groin and scrotum

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21
Q

what is tinea pedis

A

athletes foot

cracking and peeling of skin between toes

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22
Q

what is tinea capitis

A

scaly red lesions with loss of hair on scalp

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23
Q

what is tinea unguium

A

thickened nails that are discolored and brittle

onychomycosis

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24
Q

What do you use to Dx microsporum

A

direct examination of hair and skin with Woods light

will fluoresce green

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25
What does candida albicans cause
oral thrush, diaper rash and vaginitis
26
how do subcut fungal infections gain entrance
trauma to the skin
27
What causes sporptichosis
sporothrix schenckii
28
Presentation of sporothrichosis
subcut nodule that becomes necrotic and ulcerates follows lymph tracts yeast at 37 C hyphae at 25C
29
What is quick cheap Tx for sporothrichosis
Potassium iodide
30
What is chromoblastomycosis? what cause it
subcut infection caused by variety of copper-colored soil saprophytes found on rotting wood Phialophora and Cladosporium
31
Presentation of chromoblastomycosis
small violet wartlike lesion that over mo-yrs many arise nearby, look like cauliflower
32
How do you Dx chromoblastomycosis
KOH reveal copper-colored sclerotic bodies
33
What fungi cause systemic disease in humans
Histoplasma capsulatum, Blastomyces dermatidis, Coccidioides immitis
34
Describe characteristics of the fungi that cause systemic disease
dimorphic mycelial forms with spores at 25 C yeast form at 37 C
35
Where are Histoplasma and Bastomyces endemics
Mississippi River area
36
Where is Coccidioides endemic
Arizona and old southwestern areas
37
AIDS patient with opportunistic infection that previously lived in Arizona. most likley Dx?
Coccidioides
38
What are the 3 clinical presentations of the systemic fungi
asymptomatic pneumonia- like TB disseminated- rare
39
What is the best way to Dx systemic fungi
biopsy of affected tissue silver stain NOT PPD type because many people have been exposed
40
What is different of systemic fungal infections vs TB
not person to person transmission | fungi have spores, not acid fast
41
What is Histoplasma capsulatum assoc with
exposure to bat and bird droppings | cleaning chiken coops or spelunking
42
What is presentation of Blastomyces dermatitidis
weight loss, night sweats, lung involvement and skin ulcers
43
What type of fungi is Cryptococcus
polysaccharide encapsulated yeast, not dimorphic
44
What is the major manifestation of cryptococcus infection
meningoencephalitis
45
Where is cryptococcus neoformans found? what population does it infect?
pigeon poop | AIDS paitents- 10%
46
What is the risk of cryptococcal meningitis without Tx
death from cerebral edema and brainstem compression
47
What is the Dx for cryptococcus infection
lumbar puncture and CSF analysis
48
What does the India ink stain of cryptococcus look like
halo of polyscarrachride capsule around yeast cells
49
What is the most sensitive/confirmatory cryptococcal lab
cryptococcal Ag test
50
What are the 3 cutaneous infections caused by Candida
oral thrush- creamy white exudate Vaginitis- cottage cheese diaper rash- red and macerated
51
What can candida cause in immunocompromised host
esophagitis- burning substernal pain worse with swallowing disseminated- every organ see white fluffy candidal patches in retina
52
What is the clinical pearl of candida detection in samples
normal in urine, stool and sputum | abnormal in blood!!!! immunocompromised
53
What 3 types of diseases are caused by Aspergillus
Allergic Bronchopulmonary Aspergillosis (ABPA) infection in preformed lung cavities "Aspergilloma" invasive infection of lung "invasive aspergillosis"
54
What type of reaction is ABPA
type 1 HS reaction IgE mediated with bronchospasm blood eosinphilia also type 4 DTH with cell mediated inflammation and lung infiltrates
55
What is an aspergilloma
lung cavitations from TB or malignancies that grow aspergillus fungal ball in cavity
56
What is Tx for aspergilloma
surgical excision
57
What is presentation of invasive aspergillosus
slowly progressive asymptomatic pneumonia, multiple nodular infiltrates high mortality rate
58
What toxin does aspergillus secrete? where is it most prominent?
Aflatoxin | peanuts grains and rice in sahara desert in Africa
59
What patients are at highest risk for mucormycosis infection
profound acidotic patients like diabetics, immunocompromised, burn patients or those taking iron chelator deferox-amine
60
What areas do the mucormycosis fungi infect
sinuses, cranial bones and blood vessels
61
What are the fungi like bacteria
Actinomycetes and Nocardia
62
What is important about Actinomycetes
``` gram + filamentous beaded anaerobe normal flora eroding abscesses sulfur granules treat with Penicillin ```
63
What is important about Nocardia
gram + beaded filamentous ACID FAST not normal flora misDx as TB alot Tx with sulfamethoxazole