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Flashcards in Medical Mycology Deck (74)
1

What are the characteristics of fungus?

eukaryotic
contain a nucleus
contain membrane bound organelles
Heterotrophic
-lack chlorophyll (not autotrophic)
- saprophytes (feed on living and dead organic matter) or parasitic (utilize living tissue)
Thermally dimorphic (mostly) - can exist in different forms based on temperature
Kingdom - Mycota

2

Which agent is associated with Meningitis in the immunocompromised?

Cryptococcus

3

What is the structure of the fungus?

Cell wall - antigenic, multilayered
- Polysaccharides (chitin, chitosan, cellulos, glucan, mannan)

Cell membrane:
- bilayered made of phospholipids and sterols (ergosterol, zymosterol)
-protects the cytoplasm and facilitates capsules and cell wall synthesis

Cytoplasm:
-nucleolus, ER, mitochondria

Polysaccharide Capsule -*****Cryptococcus neoformans**

4

What is the encapsulated yeast we are supposed to know?

Cryptococcus neoformans
-antiphagocytic
-agglutination reaction

5

What is thermal dimorphism?

Two different forms based on temperature
Yeast (at 37 degrees)
- unicellular
- reproduces asexually by budding
- also sexually >>>basidiospore
- India ink can be used to identify
- all yeasts are aerobic and grows at wide range of temperature

Filamentous (Mold)
-multicellular
-vegetative growth of filamentous
- aerobic filamentous fungi
- mass of hyphae make up "Mycelium"

6

What is a septae hyphae?

hyphae separated by septum

7

The spores will become (mold/yeast).

mold

8

Distinguish between pseudohyphae, non-septate, and septate?

Non-septate (coenocytic)
Septate
Pseudohyphae (lack cytoplasmic connections between cells)

9

What does pathogenesis depend on?

immune response
structure of fungus

10

What will a fungal infection cause?

granuloma somewhere

11

How are fungal infections transmitted?

environment
Most are not communicable (except dermatophytes)

12

What agars are used to identify fungus?

Sabouraud's agar
Blood agar
microscopy

13

What do the antifungal drugs work on?

Ergosterol synthesis (makes up cell membrane)
-allylamines
-azoles
-morpholines
-polyenes
-amphotericin B (lots of side effects)
-nystatin

14

What are 4 types of fungal infections?

superficial
subcutaneous
systemic
opportunistic

15

What subcutaneous infection do we need to know?

sporothrix schenckii

16

What does superficial mycoses affect?

epidermis at the stratum corneum layer
-not invasive
- normally no pathological change

17

How is dermatophyte diagnosed?

Branched hyphae on KOH wet mount
-culture - myobiotic sugar
-Sabourand's dextrose sugar
Wood's light

18

All dermatophyte infections are caused by members of what 3 genera?

- microsporum
- epidermophyton
- tricophyton

19

What is tinea corparis?

ringworm (trunk, arms, legs)

20

What is tinea cruris?

jock itch (groin)

21

What is tinea pedis

athlete's foot

22

tinea capits

ringworm of scalp

23

Tinea unguium

nail fungus

24

Tinea manus

ringworm of hand

25

What is white piedra caused by?

Tinea blanca
Trichosporon beigelii

26

What is black piedra caused by ?

Piedra hortae

27

What treatments are available topically? oral?

topical (miconazole, clorthrimazole)
oral (Griseofulin, Ketaconazole)

28

What is the name of the organism that causes pityriasis versicolor?

Malassezia furfur

29

How is Malassezia furfur diagnosed?

presence of branched hyphae resembling spaghetti and meatballs

30

How does the Malassezia furfur yeast appear?

spherical on KOH mount

31

Who is at risk for Sporothrix schenckii?

golfers, rose gardeners, landscapers

32

What is the distribution of Sporothrix schenckii?

world wide, mainly in tropical areas

33

How is Sporothrix schenckii transmitted?

traumatic implantation

34

What does Sporothrix schenckii cause?

Rose Gardener's disease
Sportrichosis

35

What can candida albicans cause orally?

thrush

36

What fungus can be transmitted person to person?

candida albicans

37

How are systemic fungal infections transmitted?

inhalation
thermally dimorphic
-to lung
-will give rise to yeast in body- single cell and budding
**not communicable

38

What happens when macrophage encounters yeast?

granuloma will form
chest x-ray will show consolidation

39

Describe Histoplasma capsulatum's geographical location.

Geographical distribution (Ohio-Mississippi River valley)
loves nitrogen in soil

40

Where is Histoplasma capsulatum found?

bat, pigeon, and chicken droppings

41

Who is at risk for Histoplasma capsulatum?

access to chicken coops, spelunking

42

How would you diagnose Histoplasma capsulatum?

yeast is budding with narrow base***
KOH and Parker Ink
Look for H- Antigen

43

What will happen in 95% of cases of Histoplasma capsulatum?

nothing

44

Clinical symptoms of Histoplasma capsulatum may resemble what disease?

TB pneumonia

45

Where is Blastomyces dermatitidis geographically located?

East of Mississippi River Valley
Central America

46

Where is Blastomyces dermatitidis found in nature?

soil, rotten wood
beaver dam

47

Describe the structure of Blastomyces dermatitidis ,

Round yeast with double refractive wall and single broad based budding

48

What does Blastomyces dermatitidis cause?

Chicago disease
fever
night sweats
cough up blood

49

Which fungus is the most endemic?

Coccidiodes immitis

50

Where is Coccidiodes immitis geographically located?

SW United States
San Joaquin valley

51

Why is Coccidiodes immitis so important?

transmission is via a spherules through inhalation of arthrospore
-sac ruptures and releases

52

What is the geographic location of Paracoccidiodes

Rural Latin America and some of South America

53

What has multiple, narrow base budding yeast cells
"steering wheel"?

Paracoccidiodes brasiliensis

54

What population would be susceptible to Cryptococcus neoformans?

immunocompromised
AIDS patients

55

Where is Cryptococcus neoformans found?

associated with soil contaminated with pigeon droppings

56

Which fungal organism causes meningitis?

Cryptococcus neoformans

57

How would you confirm Cryptococcus neoformans?

lumbar puncture
CSF culture

58

Which organism stains with India ink?

Cryptococcus neoformans (encapsulated)

59

How is Cryptococcus neoformans transmitted?

inhalation>> colonizes the lung>>lung injury

"Cryptococomas"

60

What disease can result from Candida?

diaper rash
endocarditis (IV drug users)

61

What pH does Candida require?

pH 7.4

62

Which bacteria can maintain the pH so that Candida cannot grow?

lacto bacillus

63

When is esophageal candidiasis seen?

immunodeficiency

64

What population does Disseminated candidiasis affect?

immunocompromised
IV drug users

65

Where is Aspergillus funigatus found?

world wide

66

In the body and environment Aspergillus funigatus exists in what form?

acute angle hyphae form with septae
flowering head
(no head, no thermal dimorphism)

67

How is Aspergillus funigatus transmitted?

inhalation or traumatic inoculation of conidia

68

What are the signs and symptoms of Aspergillus funigatus?

release of mycotoxins>>>>mycotoxicosis
Aflatoxin via corn or nuts

Ergots

69

Where does Aspergillus funigatus colonize?

preformed cavities and debilitated tissues

70

Zygomycosis is associated with what 3 species?

Rhizopus
Mucor
Rhizomucor abisdia

71

Zygomycosis is seed in what population?

immunocompromised
old
diabetic

72

How would Zygomycosis appear under a microscope?

hyphae with wide branches, no septae

73

What causes fungal pneumonia?

Pneumocystis jiroveci (AIDS defining illness)
CD4 count < 100

74

What are risk factors for Pneumocystis jiroveci ?

CD4 < 200 cells/uL
Prior PCP infection
oral thrush
recurrent bacterial pneumonia
HIV