The KOH test for fungus is conducted on an outpatient basis and patients do not need to prepare in advance. Results are usually available while the patient waits or the next day if sent to a
clinical laboratory. The KOH test procedure may be performed by a
physician,
nurse practitioner, physician associate, medical assistant, nurse, midwife or medical laboratory technician. If fungal cultures are required, the test is performed by a technologist who specializes in microbiology. • Collection: Skin, nail, or hair samples are collected from the infected area on the patient. For skin samples, a scalpel or edge of a glass slide is used to gently scrape skin scales from the infected area. For hair samples, a forceps is used to remove hair shafts and follicles from the infected site. If the test is being sent to a laboratory, the scrapings are placed in a sterile covered container. • The scrapings are placed directly onto a microscope slide and are covered with 10% or 20% potassium hydroxide. • The slide is left to stand until clear, normally between five and fifteen minutes, in order to dissolve skin cells, hair, and debris. • To enhance clearing
dimethyl sulfoxide can be added to the slide. To make the fungi easier to see
lactophenol cotton blue stain can be added. • The slide is gently heated to speed up the action of the KOH. • Adding
calcofluor-white stain to the slide will cause the fungi to become fluorescent, making them easier to identify under a
fluorescence microscope. • Place the slide under a microscope to read. ==Evaluation==