Dimorphic Fungicontinued Clinical Microbiology Review 270
FUNGUS INFECTION MOLD PHASE YEAST PHASE OTHER
Histoplasma
capsulatum
Sporothrix schenckii
Endemic in Ohio & Mississippi
River valleys. Soil saprophyte.
Found in manure of chickens,
pigeons, bats. Acute pulmonary
disease that can be self-limited
or spread. Predilection for RE
system. Tissue phase may be
confused with Leishmania.
Serological tests & nucleic acid
probes available.
Found in Mississippi & Missouri
River valleys. Found on rose
bushes, barberry bushes, sphag-
num moss, mulch. Usually infects
farmers or florists. Introduced
by trauma, usually to hand.
Cutaneous lesions spread along
lymphatics.
Silky, white to gray-tan
colonies. Thick-walled
spherical macroconidia,
7–16 μm, surrounded
by finger-like projec-
tions. “Tuberculate
chlamydospores”
White to yellow colonies.
Clusters of pear-shaped
conidia at tips of conid-
iophores. “Flowers”
Histoplasmosis
(spelunker’s disease,
Darling’s disease)
Sporotrichosis
(rose gardener’s
disease)
1–4 μm round to oval. In-
tracellular in phagocytes
of blood or bone marrow.
Gram pos cigar-shaped
cells. Usually not seen in
direct smears unless by
immunofluorescence.
