Dimorphic Fungi Clinical Microbiology Review 269
FUNGUS INFECTION MOLD PHASE YEAST PHASE OTHER
Blastomyces
dermatitidis
Paracoccidioides
brasiliensis
Coccidioides immitis
Endemic to Ohio & Mississippi
River valleys. Usually in farmers
who contract from soil. Begins in
lungs. May become systemic.
Mainly in Brazil, Argentina,
S. Mexico. Begins in lungs. Can
become systemic.
Found in desert of Southwest
U.S. More common in dark-
skinned men. Spores are inhaled
or contaminate injured skin.
Affects respiratory tract 1st. Can
spread to other organs. Caution:
Arthrospores highly infectious.
Serological tests available.
White to gray-brown
colony. Hyaline, septate
hyphae with small oval
conidia borne singly at
tips of conidiophores.
“Lollipops.”
Resembles Blastomyces
Fluffy or powdery white
to gray-tan colonies.
Barrel-shaped
arthrospores.
North American
blastomycosis
(Gilchrist’s disease)
South American
blastomycosis
Valley fever
8–15 μm. Round, thick
walled. Single bud con-
nected by wide neck.
10–30 μm. Round, double
walled. Multiple buds
pinched at attachment.
“Mariner’s wheel.”
Spherule 20–80 μm
containing numerous
endospores.
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