3 - Direct Microscopic Examination

KOH dissolves _ in skin, hair, nails to make fungal elements visible.

keratin

KOH also lyses _, WBCs, RBCs, mucus, debris.

epithelial cells

A _ is used with moistened cotton to prevent KOH from drying during incubation.

Wet chamber

Hair needs _ min in KOH.

5-10 min

Skin scales/crusts need _ min in KOH.

20-30 min

Nail clippings need _ in KOH.

several hours

_ gives faster maceration and clearing than KOH alone, but preparations do not keep.

DMSO

The “_” appearance describes yeast cells and hyphae in pityriasis versicolor caused by Malassezia furfur.

Spaghetti and meatballs

_ binds to chitin and fluoresces under UV light when mixed with KOH.

Calcofluor White/Cellufluor

_-shaped conidia are characteristic of Blastomyces dermatitidis on Calcofluor.

Lollipop

India Ink detects Cryptococcus neoformans in CSF by showing a _ around encapsulated yeast.

zone of clearance or "halo"

_ is the best stain for fungal elements in histologic sections; fungi stain black due to silver reduction.

Grocott-Gomori’s Methenamine Silver Nitrate Stain

_ stains polysaccharides and mucosubstances pink-purple.

PAS Stain

PAS reactive fungi include Candida albicans, Aspergillus fumigatus, _

Cryptococcus neoformans

_ is used for bone marrow and peripheral blood smears to detect Histoplasma capsulatum and Cryptococcus neoformans.

Wright Stain

Fungi are _ the size of gram-positive cocci.

2-3x

_ contains lactic acid to preserve structures, phenol to disinfect, and cotton blue to stain chitin.

Lactophenol Cotton Blue (LCPB)

The _ technique uses a 2cm x 2cm cellotape flag and 95% ethanol to observe fungi as they sporulate.

Adhesive Tape/Cellotape Flag

_ culture uses a 5 mm square block of Saboraud Dextrose Agar and is best for definitive ID, but least practical.

Microslide

_ is the most helpful feature for mold identification.

Growth rate

Dimorphic fungi are slow, _ for visible colonies.

1-4 weeks

_ are rapid growers, producing cottony/wooly colonies within 24 hours and are called lid lifters.

Zygomycetes

Spherules of Coccidioides immitis may contain _ or be empty.

endospores

_ are brown, round pleomorphic thick-walled cells with transverse septations seen in chromoblastomycosis.

Sclerotic bodies/fission bodies

_ are found in subcutaneous mycosis called mycetoma; septate hyphae surrounded by a thick rind.

Phaeomycotic granules