medically important yeast Flashcards
characteristic of yeast
SIMPLE in sporulation and nutritional
ID: sugar assimilation
look for blastospores or produce pseudohyphae
what is yeast plated on for enhancement of sporulation
corn meal agar or potato dextrose
how does yeast look on plate
creamy, whitish colonies
some are wrinkled and dry
can ID yeast on wet mount
yeast and flora
can be normal flora
but can be pathogenic in immunocompromised host
most common yeast
candida albicans
Candida albicans infection
in oral, vaginal, wound, urinary
can cause thrush- oral infection after antibiotics or chemo- can be systemic
candida albicans is what +
germ tube +; outgrowth of organism in pooled human serum
Candida albicans growth
mycosel or SABs
production of blastospores, pseudohyphae and chlamydospores
what sugar does Candida albicans assimilate
many sugars but MAIN
trehalose
C. dubliniensis is germ tube + but how to differentiate between albicans
does not assimilate trahalose
C. tropicalis
-UTIs
immunocompromised
virulent in leukemia
C. tropicalis growth
produced blastospores either singly or short groups
DOES NOT GROW ON cycloheximide agar (mycosel)
candida kefyr
pseudotropicalis
blastospores- logs in a stream
ID on corn meal and seeing blastospores
nail or pulmonary infections
second most candida species to cause infection
C. glabrata
C. glabrata main differentiating characteristics
ONLY assimilates trehalose and glucose
does not produce pseudohyphae
C. glabrata infection
can be systemic and get into blood stream so infections can be aggressive
beginning to show resistance to fungal drugs
yeast interest in hospitals
candida auris
-spread easily from personnel to patients
-reportable due to high resistance
C. auris why serious
in some cases resistant to all anti-fungal
serious when isolated in the bloodstream
“superbug”
BIG BLASTOSPORES
yeast contaminate around house
rhodotorula
-sinks, bathroom
rhodotorula infection
-orange/salmon color
-contaminant normally
-ONLY isolated from very sick patients -end stage carcinoma or leukemia
-no pseduohyphae
baker’s yeast
saccharomyces cerevisiae
saccharomyces cerevisiae reproduction
both sexual and asexual stage and can convert by placing on V8 juice with SABs
rarely source of infection, but increase in HIV pt
seen on tomatoes and other fruit
geotrichum
machinery mold
associated with lung infections
important info about geotrichum
grows best at 30 not 37
produces arthrospores that do break apart as gets older
dryish wrinkled colony growing on corn meal
common form of yeast meningitis in AIDs patients
cryptococcus neoformans
-invade any tissue
what harbours Cryptococcus neoforms
pigeons and trees
not contagious person to person
from nature
brownish colonies on bird seed agar
Cryptococcus neoforms important
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
known to cause cutaneous skin infection
trichosporum beigelli
infection known as white piedra
not common in US
infection of trichosporum beigelli
superficial infection of hair and can see white nodules along hair shaft
how to differentiate between trichosporum beigelli and geotrichum
trichosporum beigelli produced arthrospores and blastospores with pseudohyphae
geotrichum- no blastospores
yeast that causes pityriasis versicolor
Malessezia furfur-normal skin flora
discoloration of the skin
can be dark or light patches on skin
Important about Malessezia furfur
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
