Sporotrichosis

ByPaschalis Vergidis, MD, MSc, Mayo Clinic College of Medicine & Science
Reviewed/Revised Nov 2023
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Sporotrichosis is an infection caused by the fungus Sporothrix schenckii.

  • The infection develops when the fungi enter the body through small cuts and scrapes in the skin.

  • Usually, the skin and nearby lymph nodes are infected, resulting in bumps on the skin and swollen lymph nodes.

  • Rarely, the lungs, joints, or other parts of the body are infected.

  • Diagnosis requires culture and identification of the fungus in a sample of infected tissue.

  • Itraconazole is used to treat most infections, but amphotericin B is required for bodywide infections.

(See also Overview of Fungal Infections.)

Sporothrix fungi typically grow on rose bushes, barberry bushes, sphagnum moss, and other mulches. In contrast to many other fungal infections, Sporothrix fungi are not usually inhaled but rather enter the body through small cuts and scrapes in the skin. Most often, infections occur in farmers, gardeners, horticulturists, and timber workers.

Sporotrichosis affects mainly the skin and nearby lymphatic vessels.

Very rarely, a lung infection occurs after spores are inhaled.

Also very rarely, bones, joints, or the brain and spinal cord are infected, usually in people with a weakened immune system, such as those with AIDS.

Symptoms of Sporotrichosis

In sporotrichosis, an infection of the skin typically starts on a finger or hand as a small, painless bump (nodule). The bump slowly enlarges and forms an open sore.

Sporotrichosis
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Sporotrichosis starts as a small bump that slowly enlarges and may form an open sore.
Image courtesy of www.doctorfungus.org © 2005.
Sporotrichosis: Nodules
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The small bumps caused by sporotrichosis may slowly enlarge and form an open sore. Over the next several days or weeks, the infection spreads through the lymphatic vessels of the finger, hand, and arm to the lymph nodes, forming more nodules and open sores.
Image courtesy of www.doctorfungus.org © 2005.

Over the next several days or weeks, the infection spreads through the lymphatic vessels of the finger, hand, and arm to the lymph nodes, forming more nodules and open sores along the way. Pus from the lymph nodes may break through the skin, causing an opening that infected material drains through. Even at this stage, there is little or no pain. Usually, people have no other symptoms.

This infection is seldom fatal.

Severe Sporotrichosis
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If untreated, sporotrichosis may spread along the lymphatic vessels of a finger, hand, and arm, causing open sores on the skin along the way. In this photo, open sores have been infected by other bacteria, causing more widespread infection of the skin.
Image courtesy of Dr. Lucille Georg via the Public Health Image Library of the Centers for Disease Control and Prevention.

Other symptoms are rare. An infection in the lungs may cause pneumonia, with a slight chest pain and cough. Lung infection usually occurs in people who have another lung disorder, such as emphysema.

Joint infection causes swelling and makes movement painful.

Very rarely, sporotrichosis spreads throughout the body. Such infections are life threatening and are more common among people with a weakened immune system.

Diagnosis of Sporotrichosis

  • A doctor's evaluation

  • Culture of samples of infected tissue

The characteristic nodules and sores may lead a doctor to suspect sporotrichosis, especially in people who may have been exposed to the fungus (for example, gardeners, landscapers, and foresters).

The diagnosis is confirmed by growing (culturing) and identifying Sporothrix in samples of infected tissue.

Treatment of Sporotrichosis

  • Antifungal medications

itraconazole. Treatment takes 1 year altogether.

Itraconazole helps prevent sporotrichosis from recurring while the immune system is weak.

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