Quick Review Cards for Medical Laboratory Science

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.

continued...