Medically important yeast Flashcards
Yeasts produce asexually by ______
Budding (blastoconidia formation)
Yeasts produce sexually by _____
ascopores / basidiospores
An outpouching of cell wall that becomes tubular and with no constriction
Germ tube
Elongate, resemble links of sausage and with cell wall constrictions
Pseudohyphae
Best way to identify yeast
Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS)
Most commonly encountered opportunistic fungi
Candida spp.
Candida spp. may be recovered from?
Oropharynx
GI tract
Genitourinary tract
Skin
It is considered part of the normal oropharyngeal microbiota
Candida spp.
Candida infection that surrounds the toe/finger nail
Paronychia
Fungal infection of nail and nail bed
Onychomycosis
Candida infection in the area where two skin touch/rub
Intertriginous candidiasis
Yeast in blood
Fungemia / Candidemia
Non-albicans candida that is more common in adults
C. glabrata
Common in patients w/ hematologic malignancies
C. tropicalis
Primary cause of fungemia and the 2nd most common Candida isolate
C. parapsilosis
(True or False): Candida spp. are strongly gram negative
False (positive)
Colonies appear starlike or possess feet-like projections
C. albicans
C. glabrata ferments and assimilates ______ & ______
Glucose & Trehalose
C. tropicalis ferments and assimilates _____ & _____
Sucrose & Maltose
It is well recognized in patients w/ AIDS
Cryptococcal Meningitis
The capsule that helps C. neoformans survive passage thru pigeon gut
Polysaccharide capsule
(True or False): The degree of infection depends on the variant from the yeast
False (depends on host immune status)
It acts as a virulence factor by making the organism resistant to leukocyte attack
Phenoloxidase
The most widely used method for the rapid detection of C. neoformans
India ink preparation
6 medically important yeasts
Candida spp. Cryptococcus spp. Malassezia sp. Rhodotorula spp. Saccharomyces cerevisiae Trichosporon spp.
How many days does C. neoformans appear on culture media?
1-5 days
C. neoformans appears what color on niger seed agar
Brown
C. neoformans appears what color on inhibitory mold agar
Golden yellow
A skin infection characterized by superficial, brownish scaly areas
Tinea versicolor
It causes tinea versicolor
Malassezia furfur
The morphology of M. furfur is commonly described as?
Spaghetti and meatballs
It is recognized as oval or bottle-shaped cells that exhibit monopolar budding
Malassezia furfur
Agar medium for the cultivation of Malassezia furfur is overlaid with a long fatty chain acid or ____
Olive oil
A normal resident microbiota of human skin
Rhodotorula spp.
Rhodotorula spp. resembles what opportunistic fungi
Cryptococcus spp.
Typically recovered from moist environmental sources
Rhodotorula spp.
Color of Rhodotorula spp. colonies on SDA
Orange/red
Common yeast used in baking and a variety of food products
Saccharomyces cerevisiae
Trichosporon organisms are recovered occasionally from?
Respiratory tract secretion
Skin
Oropharynx
Stool
It is characterized by soft, yellow or pale brown aggregations around hair shafts
White piedra
It causes white piedra
Trichosporon spp.
It is the most commonly accepted and economical method used to identify yeast
Germ tube test
Pseudohyphae / hyphae is rarely seen on what yeast?
Cryptococcus spp.
A Chlamydoconidia is present on the hyphae of what yeast?
Candida albicans
A Rudimentary hyphae is sometimes present on what yeast?
Saccharomyces spp.
(True or False): 1-5 days of incubation is required for Rapid urease test
False (1-2 days)
Useful in screening urease producing yeast
Rapid urease test
Used as presumptive identification of C. glabrata
Rapid trehalose test
Used a presumptive identification of C. neoformans
Rapid selective urease test
3 methods used before final identification of C. neoformans
Cornmeal agar morphology
Carbohydrate utilization
Phenoloxidase detection (using Niger seed agar)
(True or False): C. neoformans readily produce phenoloxidase
True
Most common used conventional method for definitive identification of yeasts
Carbohydrate utilization
