What is a Dermatophyte?

What is a dermatophyte? The simple answer to this is that a dermatophyte is a skin-loving fungus. Dermatophytes are fungi that are adapted to live in animal tissues that contain keratin—the protein found in skin, hair, nails, hooves, and horn. Keratin is a tough protective substance that gives these tissues their firm texture. Dermatophytes are capable of breaking down keratin to obtain nutrients.

The extent of fungal nail and skin infections is normally limited to tissues that are not technically alive. Nails, hair, and the top layers of our skin are continually replenished by more growth from beneath; however, these tissues don’t have a blood supply and antibodies can’t readily reach fungi that grow there. Any answer to the question ‘what is a dermatophyte,’ should include the limitation that skin loving fungi typically only grow on, and break down, dead skin cells. They do not spread to other areas of the body unless the immune system is compromised.

The textbook answer to ‘what is a dermatophyte’ also excludes a number of other fungi that are sometimes implicated in fungal nail and skin infections. Most of these are environmental species that normally live on decaying organic material—compost, leaf litter, humus, animal remains etc.—and only rarely make the jump to living things. It’s generally agreed that these fungi can cause onychomycosis (fungal nail infections) but don’t invade skin. Various species of yeast are candidates as well, but they, too, are well known only in nail infections.

What is a dermatophyte? Specifically, it’s a fungus belonging to one of three fungal genera: Trichophyton, Microsporum, and Epidermophyton. A number of species within each genera cause fungal nail and skin infections; however, not all species do so. To recap: while being uniquely capable of living on and breaking down the hair, skin, nails, hooves, and horns of living humans and animals, dermatophytes rarely invade other parts of the body except when there is a problem with the immune system.

Tests for Nail Fungus

The only way to know for sure whether you’re suffering from nail fungus infection (onychomycosis) is to order tests for nail fungus. Only a medical doctor can do this, so the first step is to visit your doctor if you have not done so already. Your doctor may take a sample while you are in the office and send it to the lab for testing, or he or she may ask you to collect the specimen yourself and deliver it to the lab.

The best specimen for nail fungus diagnosis is nail filings or clippings collected from the part of the nail that is most severely affected. Typically, onychomycosis results in crumbly brittle nails, so it is not difficult to obtain a sample. While collecting the sample, take care not to scatter bits of the nail around as these may be infectious to you and others. In the laboratory, the filings will be used to set up cultures and other tests for nail fungus.

Many laboratories provide a specimen kit for collecting a sample for nail fungus diagnosis. Typically this kit will consist of a piece of black or dark construction paper that is folded into a compact packet, and an envelope. It’s important to use the dark paper because tiny pieces of nail show up better against a dark background: laboratory personnel will be better able to find all the pieces of nail you submit for tests for nail fungus. Place your sample in the center of the paper and fold it up securely so that nail clippings cannot fall out. Ensure that the envelope has your name and your doctor’s name, and any other pertinent information on it.

Nail fungus tends to grow very slowly, even in the laboratory, so results from tests for nail fungus can take a long time to arrive in your doctors office—it’s not unusual for a final report to take at least four weeks. Preliminary results can arrive more quickly however – if a microscopic examination of the nail sample reveals fungal elements, or something significant grows quickly in the culture, the laboratory will likely tell your doctor this to help with rapid nail fungus diagnosis.

Waiting for tests for nail fungus may seem like an inconvenient, lengthy, and costly procedure, but remember that a number of other nail conditions can mimic onychomycosis. Before you start treatment, it’s wise to be sure that the nail fungus diagnosis is correct.