KOH test

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The KOH test is a procedure in which potassium hydroxide (KOH) is used to detect fungi by dissolving human cells in a culture. The difference in cell wall composition of human cells and fungal cells allows this procedure to help distinguish the two cells. KOH denatures the proteins in the human cell; only the fungal cells remain to be seen under the microscope.

KOH test procedure:

  1. Take scraping from margin (not center) of lesion
  2. Place on clean slide
  3. Add 2-3 drops of 10% KOH in water
  4. Warm the slide (don't boil)
  5. Optional - add 1 drop of lactophenol cotton blue
  6. Add cover slip
  7. Examine immediately under high dry magnification with light microscope

It is used to detect whether a patient has Athlete's foot and many other fungal infections.