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Flashcards in Medical Mycology Deck (36):
0

saprophytes

feed on living and dead organic matter

1

Encapsulated yeast

crypotoccus neoformans

2

Yeast

cultured at 37oC
unicellular
reproduces asexually by budding -> blastoconida
reproduce sexually -> Basidiospore
may contain a capsule - use india ink to ID
ALL are aerobic
grow at wide range of temps, best is room temp

3

Filamentous (mold)

vegetative growth of filamentous (filaments packed tightly)
aerobic filamentous fungi
reproduction by spores or conidia
also known as Hyphae

4

Mycelium

mass of hyphae

5

Transmission of Fungi

most are opportunistic
many switch to hyphal form as invade host
most are not communicable except dermatophytes
enter via respiratory route, mucous membrane and the skin

6

sabouraud's agar

contains pentons, good for dermatophytes
pH is 5.6 to inhibit growth of bacteria

7

Blood agar

usually with antibiotics to prevent cross contamination

8

Microscopy

skin scrapings with 10% KOH
Light microscopy

9

superifical mycoses

confined to stratum corneum (dead keratin layer of skin) or distal portions of hair
mostly cosmetic in nature
no cellular response from host
no pathological changes are elicited

10

Dermatophytes

invade keratinized structures
may cause secondary bac. infections and mild inflammation response
Dx- branched hyphae on KOH wet mount, culture ....

11

Dermatophyte infections caused by

Microsporum
Epidermophyton
Trichophyton

12

sporothrix schenckii

SubQ
mainly in tropics but seen in US
found on soil and decaying vegetation
switches to yeast in human host otherwise Hyphae in soil
at risk: gardners and landscapers

13

Rose-gardner's disease

causes sportrichosis
nodules at infection site and along draining lymph nodes
full recovery with tx but takes a while
can be disseminated in IC pts

14

Candida albicans

subQ
likes wet, moist regions
infects nail beds
Common nosocomial pathogen
Spread by sexual contact

15

Malassezia Furfur

causes Pityriasis versicolor
branched hyphae and spores - spaghetti and meatballs
Lipid dep. yeast -> infects young adults with oily skin = Lipophilic
never penetrates skin, only cosmetic
Sun fungus - see easily on darker skin

16

Furfur treatment

Selenium sulfide shampoo

17

White Piedra

caused by - Tinea blanca or Trichosporon beigelii
nodules on hair
soft,pale
on hair in groin or axilla

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Black Piedra

caused by Piedra hortae
small dark nodules seen on hair shaft

19

Systemic Mycoses

infected pts dont transmit the disease - non communicable
Large inoculum is required
Inhale the spores -> gives rise to yeast (usually lower lobes), see budding
can overcome the Cell mediated immunity

20

Histoplasma capsulatum

found ohio-mississippi river valley
Loves nitrogen in soil
found in bat,bird droppings

21

Just visited a chicken coop or went spelunking in the ohio-mississippi river valley area, what could you have just been exposed to?

Histoplasma capsulatum

22

See single budding yeast inside Macs with KOH and Parker Ink

Histoplasma Capsulatum

23

Narrow base budding yeast - thin walled
detect H antigen in Pt

Histoplasma capsulatum

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Primary Histoplasmosis

granuloma in lung
"summer flu" in Midwest
affect the spleen, liver and BM and forms granuloma - very rare - IC pts
asymptomatic in 95% cases
may resemble TB pneumonia -> Chronic progressive lung disease

25

Ocular Histoplasmosis

Risk of infection from eye surgery
"Histo spots"
loss of central vision
travel from lungs to eyes and lodge in choroid

26

Blastomyces dermatitidis

East of mississippi, central america
in soil, rotten wood and humid areas
round yeast with double refractive wall

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Detect Exo-A-Ag

Blastomyces dermatitidis

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Blastomycosis

"chicago disease"
fever, night sweats, wt loss
Granuloma in lungs and skin which may ulcerate
can affect skin, pelvis, cranial bones and ribs

29

Coccidiodes Immitis

most endemic
SW US - San Joaquin valley fever
Likes sand
most virulent of systemic mycoses

30

Sperules

c. immitis
contains lots of endospore
most infectious than Histo or Blasto

31

Fungal Meningitis in IC pts

Cryptococcus Neoformans

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Dx of Crytococcus Neoformans

CSF culture
look for cryptococcal antigens
old method - India Ink stain to detect the capsule

33

Budding yeast with capsule

Cryptococcus

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Pathogenesis of Cryptococcus Neoformans

Inhalation - colonizes lungs - Lung injury
loves Brain tissue and meninges
cryptococomas -> meningioencephalitis

35

Cryptococomas

Granuloma in CNS
Fever, loss of vision, stiff neck, sometimes vomitting
change in mental status