KOH Staining, Sputum

KOH (Potassium hydroxide) staining is a simple, non-invasive test that helps diagnose fungal infections in sputum. Cells are collected from the affected area and examined for signs of fungal infections under a microscope. A KOH test is recommended for individuals with the symptoms of fungal  skin infections such as a localized rash, red patches which are ring-shaped with scaly edges, Rashes that did not respond to or worsened with corticosteroid medications or those that persist for months

A KOH test does not explicitly identify the type of fungus; it only shows that fungus is present. In most cases, knowing the fungus precisely causing the rash may not be necessary. The doctor can make an informed judgment and prescribe treatment.