Tests and diagnosisBy Mayo Clinic staff
Your doctor will want to determine if your signs and symptoms are caused by athlete's foot or another skin disorder, such as dermatitis, psoriasis or a low-grade infection of the skin between the toes that causes the skin to split and peel (erythrasma).
Your doctor may take skin scrapings or samples from the infected area and view them under a microscope. This is called a potassium hydroxide (KOH) test. If a sample shows fungi, treatment may include an antifungal medication. If the test is negative, your doctor may examine the area with a Wood's lamp (black light) to see if there is a reddish fluorescence caused by erythrasma bacteria. If both tests are negative, a sample may be sent to a lab to determine whether it will grow fungi under the right conditions. This test is known as a culture. Your doctor may also order a culture if your condition doesn't respond to treatment.
- Goldstein A, et al. Dermatophyte (tinea) infections. http://www.uptodate.com/home/index.html. Accessed Sept. 7, 2010.
- Trevino J, et al. Tinea (dermatophyte) infections. American Academy of Dermatology. http://www.aad.org/education/students/Tineainfect.htm. Accessed Sept. 27, 2010.
- Augenbaugh W. Cutaneous fungal infections. In: Bope ET, et al. Conn's Current Therapy. Philadelphia, Pa.: Saunders Elsevier; 2010. http://www.mdconsult.com/books/page.do?eid=4-u1.0-B978-1-4160-6642-2..00013-2--sc0100&isbn=978-1-4160-6642-2&sid=1060046265&type=bookPage§ionEid=4-u1.0-B978-1-4160-6642-2..00013-2--s1795&uniqId=220345846-2#4-u1.0-B978-1-4160-6642-2..00013-2--s1795. Accessed Sept. 27, 2010.
- Dermatophyte fungal infections. In: Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 5th ed. Edinburgh; New York, N.Y.: Mosby Elsevier; 2010. http://www.mdconsult.com/books/page.do?eid=4-u1.0-B978-0-7234-3541-9..00022-5&isbn=978-0-7234-3541-9&sid=1060047096&type=bookPage§ionEid=4-u1.0-B978-0-7234-3541-9..00022-5--s0375&uniqId=220345846-3#4-u1.0-B978-0-7234-3541-9..00022-5--s0375. Accessed Sept. 28, 2010.
- Fungus infections: Tinea. American Osteopathic College of Dermatology. http://www.aocd.org/skin/dermatologic_diseases/fungus_infections.html. Accessed Sept. 29, 2010.