B3-088 - Fungi Flashcards

1
Q

Germ Tube

A

tube-like outgrowth that is beginning of a hypha

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2
Q

Pseudohyphae

A

chain of cells produced when buds fail to disassociate; constricted at septa (sausage like)

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3
Q

Hypha

A

long, branching, filament-like structure that fungi use for vegetative growth

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4
Q

Arthroconidia

A

fungal spores produced by segmentation/breakup of hyphae; usually barrel-shaped or rectangle

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5
Q

Four methods to diagnose Mycoses

A

Direct microscopic examination of specimens
Culture
Serology
Direct Molecular detection

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6
Q

Three genera of superficial fungal infections

A

Microsporum - macro- and microconidia
Trichophyton - microconidia
Epidermiphyton - macrocondia

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7
Q

Tinea group

A

aka ringworm (no worms involved)

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8
Q

Tinea barbae

A

beard areas of face and neck

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9
Q

Tinea capitis

A

scalp and hair shaft

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10
Q

Tinia corporis

A

skin on body - usually trunk

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11
Q

Tinia cruris

A

groin, perineum (between pp and booty), perianal

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12
Q

Tinea manuum

A

hands

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13
Q

Tinea pedis

A

foot

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14
Q

Tinea unguium

A

nails

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15
Q

Dermatophyte Transmission

A

Person-to-person
Gym, locker rooms
animal to person
soil to person
Touching something infected
HIGHLY CONTAGEOUS

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16
Q

Dermatophyte Symptoms

A

Itchy, red, raised, scaly patches
Blistering, oozing
Ring appearance, more red outside then center
May impact skin pigmentation
Scalp/beard: bald patches
Nails: discolored, thick, crumbling

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17
Q

Dermatophyte diagnosis

A

Based on appearance of skin
KOH test
Culture
Wood’s light

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18
Q

KOH Test

A

Skin scraping are dissolved in KOH and examined under microscope - KOH dissolves the keratin material so the fungi can be seen clearer

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19
Q

Wood’s light

A

UV light
Helps diagnose tines wapitis since hair fluoresces when infected with fungus

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20
Q

Opportunistic Systemic Mycoses

A

Candidiasis, Cryptococcosis, Aspergillosis, Mucormycosis (Zygomycosis)

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21
Q

Mucormycosis organisms

A

Rhizopus, Mucor, Rhizomucor, Lichtheimia (Absidia)
Often called “Zygomycetes” but correct term is “Mucorales”

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22
Q

Where is Mucormycosis found

A

ubiquitous in the environment
found in soil and decomposing matter (bread molds)
Clinical correlation necessary (pathogen or contaminant)

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23
Q

Mucormycosis Transmission

A

Inhalation of spores
Cutaneous or Subcutaneous inoculation
Ingestion causing GI disease

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24
Q

Mucormycosis Risk factors

A

Diabetic ketoacidosis
Chemotherapy
Transplantation
Injection drug use

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25
Q

Mucormycosis Clinical complications

A

Pulmonary
Rhinocerebral (nose to brain)
Cutaneous
Disseminated
VERY high mortality

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26
Q

Mucormycosis Diagnosis

A

Culture
Direct exam
Histopathology

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27
Q

Mucormycosis Hyphae

A

Large, wide, ribbon-like, pauciseptate branching hyphae

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28
Q

Mucormycosis colonies

A

Wooly, rapid growing, LID LIFTERS

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29
Q

Aspergillosis organisms

A

A. fumigatus: most common (90-95%)
A. niger: aspergilloma
A. flavus: produces disease in leukemic patients

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30
Q

Where is Aspergillosis found

A

Ubiquitous in the environment
Commercial uses: used to ferment rice to make sake

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31
Q

Aspergillosis transmission

A

inhalation, traumatic implantation

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32
Q

Aspergillosis risk factors

A

Neutropenia, corticosteroids, cytotoxic drugs

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33
Q

Aspergillosis Mycology

A

septet hyphae, acute angle branching
Grows rapidly

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34
Q

Aspergillosis Risk factors

A

CF
Asthma
Severely immunocompromized

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35
Q

Aspergillosis diagnosis

A

Main: Culture, Histopathology
Serologic test for antibody, galactomannan detection, molecular tests

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36
Q

Candidiasis organisms

A

C. albicans
C. glabrata
C. parapsilosis
C. tropicalis
C. krusei

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37
Q

Where is Candidiasis found

A

Ubiquitous in the environment
Normal flora of skin, GI, GU, oropharyngeal

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38
Q

Candidiasis Transmission

A

Normally endogenous in origin
Breakdown of mucosal membranes

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39
Q

Candidiasis Risk factors

A

Neutropenia, AIDS, abdominal surgery, prolonged use of Abx, immunosuppressive therapy, IV catheters, prosthetic devices, long ICU stays, renal failure

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40
Q

Candidiasis Mycology

A

Budding yeast, pseudohyphae, hyphae

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41
Q

Candidiasis Culture

A

White - buff, pasty
Rapid growth (1-4 d)
Produces some feet

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42
Q

Candidiasis Germ Tube

A

C. albicans produces GT within 2-3 of incubation in serum

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43
Q

Candidiasis Trehalose

A

C. glabrata rapidly assimilates trehalose (RAT test)

44
Q

Candidiasis Clinical disease

A

Any organ system can be involved
Common cause of the “itis’es”
Candidimia - in bloodstream

45
Q

Candidiasis specimens for culture

A

Yes: blood, bone, brain, CSF, eye
No: stool
Maybe: skin, mucous membrane, urine, vaginal, respiratory

46
Q

Candidiasis Identification

A

Germ tube test, RAT, biochemical utilization
Chromogenic media
Sequencing, MALDI-TOF MS

47
Q

Cryptococcosis organisms

A

C. neoformans
C. gattii

48
Q

Cryptococcosis Ecology

A

C. neoformans: pigeon excreta, old buildings, barns, roosts/nests, demo sites
C. gattii: subtropical, associated with eucalyptus trees, emerging in PacNW

49
Q

Cryptococcosis Transmission

A

Inhalation
Hematogenous dissemination to blood, CNS, BM, skin, bone, others

50
Q

Cryptococcosis risk factors

A

HIV, sarcoid, DMT1, transplant, corticosteroid, lymphoproliferative malignancies

51
Q

Cryptococcosis mycology

A

Roung, budding yeast, polysaccharide capsule (India ink)

52
Q

Cryptococcosis culture

A

Rapid growth
Cream/yellow/tan

53
Q

India ink test

A

Cryptococcosis detection. Less sensitive than antigen
Indian ink is excluded by capsule

54
Q

Cryptococcosis clinical disease

A

Many - asymptomatic / subclinical
Meningoencephalitis
Skin lesions

55
Q

Cryptococcosis diagnosis

A

Antigen detection - lateral flow / latex agglutination
Culture
Histology
Molecular

56
Q

Pneumocystis organism

A

Pneumocystis jiroveci
Former parasite and susceptible to anti-parasitic agents

57
Q

Pneumocystis jiroveci lacks ____ making it resistant to _____

A

Ergosterol in cell membrane; Amphotericin B

58
Q

Pneumocystis jiroveci is found

A

Unknown environmental niche.
Not culturable in lab
Commensal in respiratory tract

59
Q

Pneumocystis transmission

A

inhalation

60
Q

Pneumocystis risk factors

A

Immunocompromised (AIDS-defining illness)

61
Q

Pneumocystis clinical disease

A

PJP: Pneumocystis pneumonia
Alveoli filled with foamy exudate; impairs gas exchange

62
Q

Pneumocystis diagnosis

A

Respiratory specimens
Direct exam - cysts
Histopathology: H&E (foamy), GMS (brown colonies)
Molecular: colonization vs true pathogen?

63
Q

Dimorphic mycoses

A

Thermally dimorphic
Mold in the cold (environment)
Yeast in the beast (body)

64
Q

Dimorphic organisms

A

Blastomyces dermatitidis
Histoplasma capsulatum
Coccidiodes immitis/posadasii
Paracoccidioides brasiliensis
Talaromyces marneffei
Sporothrix schenckii

65
Q

Dimorphic mycoses are geographically _____

A

restricted

66
Q

Dimorphic mycoses transmission

A

Inhalation of conidia (mold form)

67
Q

Blastomycosis Ecology

A

Ohio and Mississippi River valley (Midwest, south-central, SE USA)
Moist soil, decomposing leaf/wood matter, lakes and ponds

68
Q

Blastomycosis transmission

A

Inhalation of fungal spores
Dissemination to skin, soft tissue, bone, GU, CNS

69
Q

Blastomycosis risk factors

A

Immunocompromised

70
Q

Blastomycosis clinical features

A

Asymptomatic
Acute - chronic pneumonia - ARDS
Cutaneous lesions
CNS, bone

71
Q

Histoplasmosis ecology

A

Worldwide
US: Ohio and MS river valley
Bat guano, bird droppings

72
Q

Histoplasmosis Transmission

A

Inhalation of microconidia

73
Q

Histoplasmosis risk factors

A

Immunosuppressed (HIV, cancer, transplant, DM)
Infants, elderly

74
Q

Histoplasmosis clinical features

A

Asymptomatic (90-95%)\
Acute pulmonary
Disseminated disease - CNS, skin, GI
Reactivation/reinfection possible

75
Q

Histoplasmosis typically grows in ____

A

12-15 days

76
Q

Coccidioidomycosis organisms

A

C. immitis
C. posadasii

77
Q

Coccidioidomycosis Ecology

A

C. immitis: CA San Joaquin valley
C. posadasii: SW USA (AZ, UT, NM, TX), MX, Central and South America

78
Q

Coccidioidomycosis transmission

A

Inhalation of fungal spores

79
Q

Coccidioidomycosis risk factors

A

African American, Filipino, pregnant women, immunosuppressed (HIV, cancer, transplant, DM)

80
Q

Coccidioidomycosis Mycology

A

Rapid growth (3-5 days)
“Barrel shaped” arthroconidia

81
Q

In tissue, Coccidioidomycosis produces ______

A

spherule

82
Q

The infections portion of Coccidioidomycosis are called _____ and are easily aerosolized

A

Arthroconidia

83
Q

Coccidioidomycosis clinical features

A

60% asymptomatic
~40% CAP (+/- rash) - Valley Fever

84
Q

Sporotrichosis organisms

A

Sporothrix schenckii

85
Q

Sporotrichosis ecology

A

Soil, decaying vegetation, rose bushes, thorns, sphagnum moss

86
Q

Sporotrichosis transmission

A

Tramatic implantation - gardening
Aerosolization - pulmonary infection

87
Q

Sporotrichosis mycology

A

Mold - clusters of conidia (rosettes)

88
Q

Sporotrichosis clinical disease

A

Rose Gardener’s disease
Cutaneous - primary lesson forms within days to weeks
Pulmonary - mimics TB
Disseminated - systemic symptoms, meningitis

89
Q

Paracoccidioidomycosis organisms

A

Paracoccidioides brasiliensis

90
Q

Paracoccidioidomycosis transmission

A

Inhalation of conidia

91
Q

Paracoccidioidomycosis risk factors

A

Occupational exposure (male, ag work)

92
Q

Paracoccidioidomycosis culture

A

Yeast - mariners wheel

93
Q

Talatomycosis organisms

A

Talaromyces (penicillium) marneffei

94
Q

Talatomycosis ecology

A

Southeast Asia (Thialand, Malasia), China, eastern India
Associated with bamboo rat

95
Q

Talatomycosis transmission

A

Inhalation of conidia

96
Q

Talatomycosis Risk factors

A

immunocomp (AIDS defining illness)

97
Q

Talatomycosis Culture

A

Diffusible red pigment
Paintbrush-like colonies

98
Q

Histoplasma Capsulatum Buzzwords

A

Bird or bat droppings
Caves, construction sites
Yeast in macrophages
Tuberculate macroconidia

99
Q

Blastomyces dermatitidis buzzwords

A

Wooded areas, often near water
camping
Broad based budding
Microconidia only (lollipopP

100
Q

Paracoccidioides brasiliensis Buzzwords

A

South America
Agricultural work
Mariners wheel yeast

101
Q

Talaromyces marneffei Buzzwords

A

SE Asia
Bamboo rat
yeast divide by fission (pill like)
Diffusible red pigment

102
Q

Sporothrix schenckii buzzwords

A

Rose gardening, sphagnum moss
Lymphatic spread
Cigar shaped yeast
Rosette-like mold

103
Q

Coccidioides immitis/posadasii

A

San Joaquin Valley, SW
4 high risk groups
Spherules
Arthroconidia

104
Q

Fungal Cultures

A

Hold for 4 weeks
Take a while to grow

105
Q

Blood cultures

A

Routine don’t grow most fungal
Fungal blood cultures grown Histoplasmas

106
Q

Serology

A

Quicker than culture
Antigen detection
Antibody detection
Sensitivity is dependent on organism
Specificity is generally good

107
Q

High antigen gross reactivity between ____ and _____

A

Histoplasma and Blastomyces