Special Lab - Mycology

Question 1

these exhibit both yeast and filamentous forms

Answer 1

dimorphic fungi
- often dependent on incubation temp

Question 2

this prevents the overgrowth of rapidly growing molds

Answer 2

cycloheximide

Question 3

we use india ink to see the capsules of this organism

Answer 3

Cryptococcus

Question 4

Mycosel agar

Answer 4

• for primary recovery of dermatophytes, pathogenic fungi, bacteria
• inhibits saprophytic fungi
• has chloramphenicol and cycloheximide

Question 5

saprophyte

Answer 5

any organism that lives on dead organic matter, as certain fungi and bacteria

Question 6

dermatophyte

Answer 6

parasitic fungus (mycosis) that infects the skin (tinea, ringworm, jock itch, athlete’s foot)

Question 7

PHY or phytone yeast extract agar

Answer 7

media for yeast and other pathogenic fungi; inhibits dermatophytes due to chloramphenicol

Question 8

T or F. CACs have hloramphenicol

Answer 8

T

Question 9

The mode of transmission for these fungi is direct contact

Answer 9

Malassezia furfur
dermatophytes

Question 10

mode of transmission of Candida sp

Answer 10

direct invasion or dissemination

Question 11

tinea vesicolor

Answer 11

Malassezia furfur (may be the cause of dandruff)

Question 12

Aspergillus

Answer 12

• inhalation
• lungs, eyes, skin, nails
• conidia

Question 13

Penicillium

Answer 13

• inhalation
• superficial
• rare
• resp. sinusitis

Question 14

Pneumocystis jirovecii

Answer 14

• inhalation
• PCP or pneumocystic pneumonia

Question 15

Histoplasma capsulatum

Answer 15

• found in bat or bird feces
• inhalation
• infects lungs, BM, blood; conidia

Question 16

T or F. Most fungi are obligate aerobes

Answer 16

T

Question 17

PAS stain for fungi

Answer 17

stains polysaccharides in cell wall bright pink or magenta

Question 18

GMS stain for fungi

Answer 18

for AP sections
stains fungi outline black

Question 19

10% KOH for skin nails and hair

Answer 19

• breaks down keratin and skin layers to easily see fungi
• may be used with calcofluor white for easier ID

Question 20

Lactophenol cotton blue

Answer 20

• stains darkly
• blue-coloured appearance of fungal spores + structures (like hyphae)
• may be used with KOH

Question 21

calcofluor stain

Answer 21

fluorescence
- stain binds to cellulose/chitin on fungal cell wall

Question 22

india ink or nigrosin

Answer 22

C. neoformans ID
- a negative stain; capsules seen as clearing
- latex agglutination more specific for ID

Question 23

yeast and YLO

Answer 23

Candida spp, C. neoformans, M. furfur

Question 24

Superficial Mycoses (dermatophytes and agents of tinea, tinea nigra and piedra)

Answer 24

NOTE: dermatophytes need keratinized tissue*

Tichophyton* Microsporum* Epidemophyton* M. furfur Candida spp

Question 25

Opportunistic mycoses

Answer 25

Aspergillus Penicillium P. jirovecii C. neoformans Candida spp

Question 26

Systemic Mycoses
level III

Answer 26

Coccoides immitis
Histoplasma capsulatum
Blastomyces dermatitidis

Question 27

ringworm

Answer 27

tinea, a superficial fungal disease of vairous b ody parts

Question 28

Which fungi exists in the mold phase in the saprophytic environment and tissue or parasitic phase in the host?

Answer 28

Histoplasma sp

Question 29

a naturally occurring fungicide produced by the bacterium Streptomyces griseus.

Answer 29

cycloheximide
- Cycloheximide exerts its effects by interfering with the translocation step in protein synthesis, thus blocking eukaryotic translational elongation