PetriKey

Lab method

Calcofluor white stain

Fluorochrome binding fungal chitin

KAL-koh-flor

stainfluorescentfunguspneumocystischitin

High-yield clue

Fungal walls and Pneumocystis cysts glowing bright apple-green/blue-white under UV is the calcofluor white clue.

Overview

A fluorescent brightener concept that binds beta-linked polysaccharides (chitin and cellulose) in fungal cell walls so organisms glow under UV/fluorescence microscopy.

Classification

  • Fluorochrome stain concept
  • UV/fluorescence microscopy
  • Chitin-binding dye
  • Rapid screening method

Lab & identification clues

  • Bright fluorescence under UV light
  • Often combined with KOH
  • Highlights hyphae, yeast, and cysts
  • Requires a fluorescence microscope

Associations

  • Rapid fungal detection vocabulary
  • Pneumocystis cyst recognition
  • Acanthamoeba and microsporidia study association

Commonly confused with

  • Lactophenol cotton blue
  • GMS silver stain

Your notes

Original concept summary for coursework. Sources checked: OpenStax Microbiology 2e and NCBI Bookshelf Medical Microbiology; reviewed 2026-06. Describes vocabulary and interpretation concepts only; not a lab protocol and not for handling specimens or identifying patient isolates.

OpenStax: Microbiology 2e staining, media, and biochemical-test foundationssourceNCBI Bookshelf: Medical Microbiology diagnostic concept foundationssource