Medically Important Yeasts Flashcards
o Spherical to elongate yeast-like cells or blastoconidia that reproduce by budding
o Colony pigmentation is usually absent
o Pseudohyphae (and occasionally true hyphae) may be present
Candida spp
o A primary or secondary mycotic infection caused by members of the genus Candida.
o 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
Common Candida spp. Isolated from Clinical Specimens
C. albicans
⮚ C. parapsilosis
⮚ C. tropicalis
⮚ C. guilliermondii (Meyerozyma guillermondii) ⮚ C. pseudotropicalis
⮚ C. krusei (Pichia kudriavzevii)
⮚ C. glabrata
Other Candida sp.
C. dubliniensis
⮚ C. lusitaniae (Clavispora lusitaniae)
⮚ C. kefyr (Kluyveromyces marxianus)
⮚ C. lipolytica (Yarrowia lipolytica)
Commensal of mucous membrane and GI tract.
Candida albicans
Microscopic morphology of C. albicans
Roundtoellipsoidalcells
Candida albicans, germ tube negative or positive?
Positive
o Germ tube positive
o Grows on media with cycloheximide
o Light green or bluish green on CHROMAgar
Candida albicans
Color of Candida albicans on Chromagar
Light green or bluish green
Dalmau Plate Morphology of Candida albicans
Presence of 1 -2 chlamydospore
o Occasional cause of candidemia and mucosal infection
Candida dubliniensis
Candida dubliniensis is Resistant to
fluconazole
Microscopic morphology of Candida dubliniensis
o Round to ellipsoidal cells
o Germ tube positive
o Grows on media with
cycloheximide
o Dark green color on CHROMAgar
Candida dubliniensis
Color of Candida dubliniensis on Chromagar
Dark green color
Dalmau Plate Morphology of Candida dubliniensis
Multiple in cluster chlamydospores
Major cause of septicemia and disseminated candidiasis.
Candida tropicalis
o Germ tube negative
o Grows on media with cycloheximide o Grows at 40 C
o Produces blue color on CHROMAgar
Candida tropicalis
Color of Candida tropicalis on chromagar
Blue
Dalmau Plate Morphology of Candida tropicalis
Presence of blastoconidia in single or double
Also known as Issatchenkia orientalis or Pichia kudriavzevii
Candida krusei
Candida krusei Intrinsic resistance to
fluconazole
Color of Candida krusei on CHROMAgar
Color pink
Dalmau Plate Morphology of Candida krusei
Abundant long wavy, cross matchstick appearance
o Recently now known as Nakaseomyces glabrata
o Causes urinary tract and blood infections
Candida glabrata
Candida glabrata Emerging resistance to
amphotericin B and fluconazole
Color of Candida glabrata on chromagar
Variable pigment
Dalmau Plate Morphology of Candida glabrata
No pseudohyphae, budding yeast only
Dalmau Plate Morphology of Candida parapsilosis
Abundant match-branch deer antler appearance
Formerly known as C. pseudotropicalis. Revised name is Kluyveromyces marxianus
Candida kefyr
Dalmau Plate Morphology of Candida kefyr
Logs in the side
Now known as Clavispora lusitaniae Candida lusitaniae
Candida lusitaniae
Candida lusitaniae
o Dalmau Plate Morphology:
Slender branch pseudohyphae or bushy short chain of blastoconidia
Now named as Yarrowia lipolytica
Candida lipolytica
Urease positive
Candida lipolytica
Candida lipolytica Macroscopic morphology
Lacy colonies that grow rapidly at 25C
Candda lipolytica dalmau plate method
No blastoconidia long pseudohyphae
o Revised nameis Meyerozyma guilliermondii
o Commonly seen on cutaneous infections.
Candida guilliermondiii
Candida guilliermondiii Macroscopic morphology
Forms cream-colored colonies at 25C
is an emerging multidrug-resistant yeast that causes invasive infections that was first described in 2009 in Japan and has since been reported from several countries (Lockhart et al. CID 2017; 64:134-140).
Candida auris
is an emerging multidrug-resistant yeast that causes invasive infections that was first described in 2009 in Japan and has since been reported from several countries (Lockhart et al. CID 2017; 64:134-140).
Candida auris
How to identify C. 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
Fungal infection of the hair shaft with white, yellowish, beige or green nodules
WHITE PIEDRA
WHITE PIEDRA Etiologic agent
Trichosporon spp.
Clinically significant Trichosporon spp
⮚ Trichosporon asahii
⮚ Trichosporon mucoides
⮚ Trichosporon inkin
⮚ Trichosporon cutaneum
⮚ Trichosporon ovoides
⮚ Trichosporon asteroides
LABORATORY DIAGNOSIS Trichosporon spp.
-Direct Microscopy
KOH
Arthrospores
-Primary isolation medium
Sabouraud’s dextrose agar
White or yellowish to deep cream colored
Barrel shape arthroconidia
Trichosporon spp
⮚ India ink (+)
⮚ Urease (+)
⮚ Canavanine Glycine Bromthymol Blue (CGB) Agar (-)
Cryptococcus neoformans
Cryptococcus neoformans Resistant to
echinocandins
⮚ India ink (+)
⮚ Urease (+)
⮚ Canavanine Glycine Bromthymol Blue (CGB) Agar (+)
⮚ Resistant to echinocandins
Cryptococcus gattii
⮚ R. mucilaginosa and R. glutinis
⮚ coral red to salmon on SDA
⮚ Urease (+)
⮚ Resistant to echinocandins and fluconazole
Rhodotorula spp.
Look identical to candida used for fermentation yeast used or probiotics
Saccharomyces cerevisiae
