Sporotrichosis

Photomicrograph of Sporothrix schenckii

• Sporotrichosis is a cutaneous (skin) infection caused by a fungus, Sporothrix schenckii.
• This infection-causing fungus is related more closely to the mold on stale bread or the yeast used to brew beer than to bacteria that usually cause infections.
• The fungus is found on rose thorns, hay, sphagnum moss, twigs, and soil. Therefore, the infection is more common among gardeners who work with roses, moss, hay, and soil.
• Occasionally, other animals such as dogs or horses may become infected.
• The disease has often been termed as "rose handler's disease" in older publications because people growing roses had a high incidence of the disease. This was due to the fact that the fungi present on rose thorns and in the moss and soil used to cultivate roses easily contaminated the small pricks and cuts on the skin made by the rose thorns.
• Peru, Brazil, U.S., China, and West Australia are the countries where most infections occur.

The disease, sporotrichosis, is caused by the fungus Sporothrix schenckii, although recent research has shown that several other distinct Sporothrix species also cause the disease. However, the disease progresses similarly for these closely related fungal species:

• Sporotrichosis usually begins when fungal spores are forced under the skin by a rose thorn or sharp stick.
• The infection may also begin in apparently unbroken skin after contact with hay or moss carrying the fungus.
• Farmers, nursery workers, landscapers, and gardeners are at higher risk for the disease because of their chance of cuts or puncture wounds while working with soil. People who are immunosuppressed (HIV patients, cancer patients, for example) are also at higher risk to get the disease.
• Rarely, cats or armadillos can transmit the disease to humans with scratches from the animal's claws.
• In very rare cases, the organism can be inhaled or ingested, leading to infection of parts of the body other than the skin. This type of systemic infection may also occur from advanced skin infections in people who are immunosuppressed.
• The disease is not transmitted from person to person, and some investigators consider sporotrichosis to be a self-limited mycosis (fungal infection not transmitted to other people).

The fungus is dimorphic (can exist as a yeast-like or hyphae-producing form). The figure below shows the hyphae (the long, filamentous parts) and conidia (spores) of Sporothrix schenckii.

• Once the fungal conidia (spores) are moved into the skin via thorns, scrapes, or other mechanisms, the disease takes days to months to develop.
• The first symptom is a firm bump (nodule) on the skin that can range in color from pink to nearly purple. The nodule is usually painless or only mildly tender.
• Over time, the nodule may develop an open sore (ulcer) that may drain clear fluid; in other instances, mycetomas may be formed. Mycetomas are areas where sinus tracts are formed from the lymph to the skin surface and discharge granules containing masses of organisms that cause the infection.
• Untreated, the nodule and the ulcer become chronic and may remain unchanged for years.
• In about 60% of cases, the fungus spreads along the lymph nodes. Over time, new nodules and ulcers spread in a line up the infected arm or leg. These can also last for years.
• In very rare cases, the infection can spread to other parts of the body.
  • The disease can infect the bones, joints, lungs, and tissues surrounding the brain (fungal meningitis).
  • Such spreading usually occurs only in people with a weakened immune system.
  • The widespread infections can be life threatening and are difficult to treat.

The symptoms are progressive. Initial sites of infection are not visibly distinctive. As the infection progresses, lesions develop, often appearing in a line as successive areas (lymph nodes) of the lymphatic channels become infected (compare figures below).

Picture of sporotrichosis lesions on a patient's finger; SOURCE: CDC/Dr. Lucille K. Georg

Picture of sporotrichosis lesions on a patient's arm; SOURCE: CDC/Dr. Lucille K. Georg

When to call the doctor

• If a person thinks they might have sporotrichosis, they should see a doctor for evaluation and treatment.
• If someone is already being treated for sporotrichosis, they should contact a doctor if new sores develop or if the old ones appear to be growing, immediately if they have a weakened immune system.

When to go to the hospital

• Uncomplicated sporotrichosis in the skin or lymph nodes is not dangerous or life threatening, so no hospitalization is needed.
• Open ulcers can become infected with bacteria and may cause a secondary bacterial infection.
• If a rapidly expanding area of redness, pain, and warmth around the original ulcers develops, a person should go to a hospital's emergency department for diagnosis.

Other infections can mimic sporotrichosis, so a doctor performs tests to confirm the diagnosis. These tests usually involve a biopsy of one of the nodules, followed by an examination of the biopsy material under a microscope to identify the pathogen. Other possible infections that are easy to confuse with sporotrichosis include the following:

• Bacteria related to tuberculosis or leprosy
• Cowpox
• Herpes
• Other fungal infections such as candidiasis, histoplasmosis, tinea capitis, and blastomycosis
• Noninfectious diseases such as lupus and sarcoidosis

The fungi can be distinguished from other organisms by culturing the fungus from lesions and then identifying its characteristic structure. This is usually done in special labs set up with trained technicians. There are other tests like fluorescent antibody identification of the fungi, but these are not widely available.

• No effective home care for sporotrichosis is known.
• Ulcers should be kept clean and covered until they are healed.

Treatment of sporotrichosis depends on the site infected and the person's overall medical condition.

• Infections in the skin only: These infections have traditionally been treated with saturated potassium iodide solution (SSKI). This medicine is given three times per day for three to six months until all the lesions have gone away. Skin infections may also be treated with itraconazole (Sporanox) for up to six months.
• Infection in the bones and joints: These infections are much more difficult to treat and rarely respond to potassium iodide. Itraconazole (Sporanox) is often used as an initial medication for several months or even up to a year. The drug amphotericin is also used, but this medicine can only be given through an IV. Amphotericin has more side effects and may need to be administered for many months. Surgery is sometimes needed to remove infected bone.
• Infection in the lungs: Lung infections are treated with potassium iodide, itraconazole (Sporanox), and amphotericin with varying amounts of success. Sometimes, the infected areas of the lung have to be surgically removed.
• Infection in the brain: Sporotrichosis meningitis is very rare, so information on treatment is not readily available. Amphotericin plus 5-fluorocytosine is generally recommended, but itraconazole (Sporanox) might also be tried.
• SSKI and itraconazole should not be used in pregnant patients. Treatment in pregnancy and of children usually requires consultation with infectious disease specialists.
• Alternative treatments for cutaneous sporotrichosis are mentioned in the lay literature. Fungicidal herbs (such as myrrh, tea tree oil, citrus seed extract, pau d'arco tea, olive oil and garlic) applied directly to the infected skin are supposed to treat the infection. However, there are few research data to back up these claims.

• Multiple follow-up visits may be needed with a doctor to make sure the disease is disappearing.
• Once the disease goes away, further follow-up care is generally not needed.

The most important step in preventing sporotrichosis is preventing mold spores from entering the skin.

• People who work with roses, hay, or sphagnum moss should cover any scratches or breaks in their skin.
• They should wear heavy boots and gloves to prevent puncture wounds.
• People with a suppressed immune system should be exceptionally careful to avoid any contact with rose thorns or soil and moss used for gardening or farm use.

Most people who have sporotrichosis only in their skin or lymph nodes make a full recovery with appropriate treatment. However, outcomes may range from good to poor if diagnosis and treatment is delayed. They are as follows:

• Treating the infection may take several months or years, and scars may remain at the site of the original infection.
• Infections involving the brain, lungs, joints, or other areas of the body are much more difficult to treat.
• Surgical removal of part of an infected organ like the lung can be a serious complication of an infection.