A fungal culture is a test to find a
fungus that can cause an infection.
Your doctor will collect a sample of skin and/or nail
fragments (debris) under the infected nail. If a sample of debris cannot be
removed, he or she will take a nail sample by lightly scraping the nail near
the infected area or by using a small blade to shave off a piece of
Nail or debris samples are added to a substance that promotes the growth of fungi. If no fungus grows, the culture
is negative. If a fungus grows, the culture is positive. The type of fungus may be identified using a microscope or
chemical tests. Sometimes other tests are done to find the right medicine for treating the fungal infection. This is
called sensitivity testing.
Why It Is Done
A fungal culture will show whether a
fungal nail infection is present and what type of
fungus it is. A fungal culture is typically done when a diagnosis is unclear or
when treatment of a fungal infection has not been successful. If uncommon fungi
are identified, the infection can then be treated with different
No fungal growth is present. But the test
may be done again using more samples taken from other parts of the infected
nail. This is because there may no longer be fungi on the edge of the infected
area, where it is easiest to scrape for a sample, or in the dead tissue, even
if you have a fungal nail infection.
Fungal growth is present, and the type of
fungus is identified. Your treatment may depend on the type of fungus
What To Think About
Although fungal cultures can
identify the type of fungus infection, they are not routinely used because they
take a long time and are expensive. Another type of culture test, called the
dermatophyte test medium (DTM) culture, can tell if dermatophytes are present.
The DTM culture costs less than a traditional fungal culture, can be done in a
doctor's office, and gives results in 3 to 7 days.
If your culture
is normal, your doctor may do other tests to determine the cause of the nail
ByHealthwise Staff Primary Medical ReviewerPatrice Burgess, MD - Family Medicine Brian D. O'Brien, MD - Internal Medicine E. Gregory Thompson, MD - Internal Medicine Adam Husney, MD - Family Medicine Specialist Medical ReviewerE. Gregory Thompson, MD - Internal Medicine Ellen K. Roh, MD - Dermatology