MEDICALLY IMPORTANT YEASTS Flashcards
- Spherical to elongate yeast-like cells or
blastoconidia that reproduce by budding
Candida spp.
- Colony pigmentation is usually absent
Candida spp.
Pseudohyphae (and occasionally true
hyphae) may be present
Candida spp.
A primary or secondary mycotic
infection caused by members of the genus
Candida
Candidiasis
- Involvement may be localized to the
mouth, throat, skin, scalp, vagina, fingers, nails,
bronchi, lungs, or the gastrointestinal tract, or
become systemic as in septicaemia, endocarditis,
and meningitis
Candidiasis
- CDC recommends that all Candida spp.
isolates obtained from a normally sterile site
(e.g., bloodstream, cerebrospinal fluid) be
identified to the species level so that appropriate
initial treatment can be administered based on
the typical, species-specific susceptibility
patterns
Candidiasis
Common Candida spp. Isolated from Clinical
Specimens
- Candida albicans
- Candida parapsilosis
- Candida tropicalis
- Candida guillermondii (Meyerozyma
guillermondii) - Candida pseudotropicalis
- Candida krusei (Pichia kudriavzevii)
- Candida glabrata
Other Candida spp.
- Candida dubliniensis
- Candida lusitaniae (Clavispora
lusitaniae) - Candida kefyr (Kluyveromyces
marxianus) - Candida lipolytica (Yarrowia lipolytica)
- Commensal of mucous membrane and
GI tract
Candida albicans
- Macroscopic Morphology:
- Creamy, smooth colonies appear rapidly at 25°C
Candida albicans
- Microscopic Morphology: Round to ellipsoidal cells
Candida albicans
- Germ tube positive
- Grows on media with cycloheximide
- Mycosel Agar (Contains
Cycloheximide) - Light-green or bluish-green on
CHROMAgar
Candida albicans
Occasional cause of Candidemia and
mucosal infection
- Candida dubliniensis
- Resistant to fluconazole
- Candida dubliniensis
- Macroscopic Morphology:
- Creamy, yeast colonies appear
rapidly at 25°C - Microscopic Morphology:
- Round to ellipsoidal cells
- Candida dubliniensis
Formerly known as Candida
pseudotropicalis. Revised name is Kluyveromyces
marxianus
Candida kefyr
Macroscopic Morphology:
- Forms cream-colored colonies
at 25°C
- Germ tube negative
- Grows on media containing
Cycloheximide
- Grows at 37°C
Candida kefy
- Now known as Clavispora lusitaniae
Candida lusitaniae
- Macroscopic Morphology:
- Forms cream-colored colonies
at 25°C - Germ tube negative
- Negative for growth on media
containing Cycloheximide - Grows at 40°C
Candida lusitaniae
- Now named as Yarrowia lipolytica
Candida lipolytica
- Macroscopic Morphology:
- Lacy colonies that grow rapidly
at 25°C - Germ tube negative
- Variable growth on media containing
Cycloheximide - Variable growth at 37°C
- Urease-Positive
Candida lipolytica
Revised name is Meyerozyma
guillermondii
Revised name is Meyerozyma
guillermondii
- Commonly seen on cutaneous
infections - Macroscopic Morphology:
- Forms cream-colored colonies
at 25°C - Germ tube negative
Meyerozyma guillermondii
____________ is an emerging multidrugresistant yeast that causes invasive infections
that was first described in 2009 in Japan and has
since been reported from several countries
Candida auris
Macroscopic Morphology
- White to cream-colored
smooth, glabrous, yeast-like
- Germ tube negative
- Variable growth on media containing
Cycloheximide
- Variable growth at 37°C
- No pseudohyphae produced on Dalmau
Plate
Candida auris
a. How to Identify Candida auris
- MALDI-TOF
- Bruker Type
- FDA-Approved CA System
database and VITEK (MALDI-TOF) MS RUO (with
Saramis Ver 4.14 database and
Saccharomycetaceae update) - Molecular Methods
b. If still in doubt…
till in doubt…
- Perform supplemental tests:
- Carbohydrate Fermentation
Test (CFT)
- Growth on media with
Cycloheximide
- Growth on 37, 40, 42, 45°C
- Urease Test
- Colony Morphology
- Fungal infection of the hair shaft with
white, yellowish, beige, or green nodules
White Piedra
White Piedra - Etiologic agent
Trichosporon spp.
6 Clinically Significant Trichosporon spp
- Trichosporon asahii
- Trichosporon mucoides
- Trichosporon inkin
- Trichosporon cutaneum
- Trichosporon ovoides
- Trichosporon asteroids
- Direct Microscopy
- KOH
- Arthrospores
white piedra - primary isolation medium
- Sabouraud’s Dextrose Agar (SDA)
White or yellowish to deep
cream-colored
Physiologic studies for white piedra
Does not ferment carbohydrates
- Urease-Positive
India Ink Positive (Small Capsule
Present)
- Growth on 37°C, Melibiose and media
with Cycloheximide are variable
- India Ink Positive
- Urease Positive
- Canavanine, Glycine, Bromothymol
Blue (CGB) Agar Negative - Resistant to echinocandins
- Cryptococcus neoformans
- India Ink Positive
- Urease Positive
- Canavanine, Glycine, Bromothymol
Blue (CGB) Agar Positive - Resistant to echinocandins
- Cryptococcus gattii
Cryptococcus gattii positive color
yellow
Cryptococcus gattii negative color
blue
- Rhodotorula mucilaginosa and
Rhodotorula glutinis - Coral red to salmon on SDA
- Urease Positive
- Resistant to echinocandins and
fluconazole
Rhodotorula spp.
- Look identical to Candida spp.
- Used for Fermentation Yeast
- Used for Probiotics
Saccharomyces cerevisiae
