medically important yeast

Question 1

characteristic of yeast

Answer 1

SIMPLE in sporulation and nutritional
ID: sugar assimilation
look for blastospores or produce pseudohyphae

Question 2

what is yeast plated on for enhancement of sporulation

Answer 2

corn meal agar or potato dextrose

Question 3

how does yeast look on plate

Answer 3

creamy, whitish colonies
some are wrinkled and dry

can ID yeast on wet mount

Question 4

yeast and flora

Answer 4

can be normal flora

but can be pathogenic in immunocompromised host

Question 5

most common yeast

Answer 5

candida albicans

Question 6

Candida albicans infection

Answer 6

in oral, vaginal, wound, urinary

can cause thrush- oral infection after antibiotics or chemo- can be systemic

Question 7

candida albicans is what +

Answer 7

germ tube +; outgrowth of organism in pooled human serum

Question 8

Candida albicans growth

Answer 8

mycosel or SABs
production of blastospores, pseudohyphae and chlamydospores

Question 9

what sugar does Candida albicans assimilate

Answer 9

many sugars but MAIN
trehalose

Question 10

C. dubliniensis is germ tube + but how to differentiate between albicans

Answer 10

does not assimilate trahalose

Question 11

C. tropicalis

Answer 11

-UTIs
immunocompromised
virulent in leukemia

Question 12

C. tropicalis growth

Answer 12

produced blastospores either singly or short groups

DOES NOT GROW ON cycloheximide agar (mycosel)

Question 13

candida kefyr

Answer 13

pseudotropicalis

blastospores- logs in a stream

ID on corn meal and seeing blastospores

nail or pulmonary infections

Question 14

second most candida species to cause infection

Answer 14

C. glabrata

Question 15

C. glabrata main differentiating characteristics

Answer 15

ONLY assimilates trehalose and glucose

does not produce pseudohyphae

Question 16

C. glabrata infection

Answer 16

can be systemic and get into blood stream so infections can be aggressive

beginning to show resistance to fungal drugs

Question 17

yeast interest in hospitals

Answer 17

candida auris

-spread easily from personnel to patients
-reportable due to high resistance

Question 18

C. auris why serious

Answer 18

in some cases resistant to all anti-fungal

serious when isolated in the bloodstream

“superbug”

BIG BLASTOSPORES

Question 19

yeast contaminate around house

Answer 19

rhodotorula

-sinks, bathroom

Question 20

rhodotorula infection

Answer 20

-orange/salmon color
-contaminant normally

-ONLY isolated from very sick patients -end stage carcinoma or leukemia

-no pseduohyphae

Question 21

baker’s yeast

Answer 21

saccharomyces cerevisiae

Question 22

saccharomyces cerevisiae reproduction

Answer 22

both sexual and asexual stage and can convert by placing on V8 juice with SABs

rarely source of infection, but increase in HIV pt

Question 23

seen on tomatoes and other fruit

Answer 23

geotrichum

machinery mold

associated with lung infections

Question 24

important info about geotrichum

Answer 24

grows best at 30 not 37

produces arthrospores that do break apart as gets older

dryish wrinkled colony growing on corn meal

Question 25

common form of yeast meningitis in AIDs patients

Answer 25

cryptococcus neoformans -invade any tissue

Question 26

what harbours Cryptococcus neoforms

Answer 26

pigeons and trees not contagious person to person from nature brownish colonies on bird seed agar

Question 27

Cryptococcus neoforms important

Answer 27

round yeast- india ink form a capsule which makes it virulent urea + DOES NOT grow on mycosel -plate CSF on SABs or other nutrient agar

Question 28

known to cause cutaneous skin infection

Answer 28

trichosporum beigelli infection known as white piedra not common in US

Question 29

infection of trichosporum beigelli

Answer 29

superficial infection of hair and can see white nodules along hair shaft

Question 30

how to differentiate between trichosporum beigelli and geotrichum

Answer 30

trichosporum beigelli produced arthrospores and blastospores with pseudohyphae geotrichum- no blastospores

Question 31

yeast that causes pityriasis versicolor

Answer 31

Malessezia furfur-normal skin flora discoloration of the skin can be dark or light patches on skin

Question 32

Important about Malessezia furfur

Answer 32

causative agent of sepsis in people receiving prolonged intravenous lipid therapy requires long fatty acids for growth so MUST overlay agar with layer of olive oil spaghetti meatball appearance