What is sporotrichosis

Sporotrichosis also known as “rose gardener’s disease”, is a rare subacute or chronic infection caused by a saprophytic dimorphic fungus called Sporothrix schenckii ¹⁾. This fungus lives throughout the world in soil and on plant matter such as sphagnum moss, rose bushes, and hay ²⁾. People get sporotrichosis by coming in contact with the fungal spores in the environment. Cutaneous (skin) infection is the most common form of the infection. It occurs when the fungus enters the skin through a small cut or scrape, usually after handling contaminated plant matter. Some cases of sporotrichosis have been associated with scratches or bites from animals, particularly cats.

Although only one species of Sporothrix was classically described, phenetic and genetic studies have identified additional Sporothrix species ³⁾. Sporothrix schenckii complex being most commonly found in America, Asia, and Africa. Sporothrix brasilienis has been found in Brazil and is known to be transmitted from infected cats. Sporothrix Mexicana and Sporothrix globose have also been identified throughout the world ⁴⁾. Knowledge of the geographic distribution, virulence, clinical presentation, and response to antifungal therapy of these newly identified species is an area of active research ⁵⁾.

Sporotrichosis typically presents as papules or pustules that form ulcerated nodules involving local lymphatics. Sporotrichosis is classified into cutaneous, pulmonary, and disseminated, with cutaneous the most common form of the disease. Risk factors which increase the risk of disseminated disease include patients who are immunocompromised and those with chronic obstructive pulmonary disease, alcoholism, and diabetes mellitus. General prevention is to wear gloves and long sleeves when handling soil. The gold standard for sporotrichosis diagnosis is fungal culture. First-line treatment is itraconazole ⁶⁾.

Figure 1. Sporotrichosis rash

Types of sporotrichosis

• Cutaneous (skin) sporotrichosis is the most common form of the infection. It usually occurs on a person’s hand or the arm after they have been handling contaminated plant matter.
• Pulmonary (lung) sporotrichosis is very rare but can happen after someone breathes in fungal spores from the environment.
• Disseminated sporotrichosis occurs when the infection spreads to another part of the body, such as the bones, joints, or the central nervous system. This form of sporotrichosis usually affects people who have weakened immune systems, such as people with HIV infection (see Risk & Prevention).

The characteristic infection involves suppurating subcutaneous nodules that progress proximally along lymphatic channels (lymphocutaneous sporotrichosis). Primary pulmonary infection (pulmonary sporotrichosis) is rare, as is direct inoculation into tendons, bursae, or joints. Osteoarticular sporotrichosis is caused by direct inoculation or hematogenous seeding. In rare cases, disseminated Sporothrix schenckii infection (disseminated sporotrichosis) occurs, characterized by disseminated cutaneous lesions and involvement of multiple visceral organs; this occurs most commonly in persons with AIDS. A thorough review of the topic was published by Barros et al in 2011 ⁷⁾.

Sporotrichosis outbreaks

In the United States, sporotrichosis outbreaks have occurred among people who handled sphagnum moss or hay, such as forestry workers ⁸⁾, tree nursery and garden center workers ⁹⁾ and people who worked with or played on hay bales ¹⁰⁾. Sporotrichosis outbreaks also have been reported in several other countries, including Australia, Brazil, China, Guatemala, and South Africa ¹¹⁾. Healthcare providers who are concerned about an unusual number of new cases should contact their state or local public health agency.

Who gets sporotrichosis?

Overall, sporotrichosis is rare, but people who handle plant matter such as sphagnum moss, rose bushes, or hay are more likely to get the infection. For example, sporotrichosis outbreaks have occurred among forestry workers, people who worked in tree nurseries and garden centers, and people who handled hay bales.

The severe forms of sporotrichosis (those that affect the lungs, bones or joints, or central nervous system) usually affect people with weakened immune systems or underlying diseases including diabetes, chronic obstructive pulmonary disease (COPD), alcoholism, or HIV infection ¹²⁾.

How can I lower the chance of developing sporotrichosis?

You can lower the chance of getting sporotrichosis by wearing protective clothing such as gloves and long sleeves when handling plant matter that can cause minor cuts or scrapes.

Sporotrichosis causes

Sporothrix, the fungus that causes sporotrichosis, lives in the environment in soil and on plant matter such as sphagnum moss, rose bushes, hay, or wood. The microscopic fungus can enter the skin through small cuts or scrapes. In rare cases, breathing in the fungus can cause pulmonary (lung) infection. Sporotrichosis is not contagious and can’t spread from person to person. Some cases are caused by scratches or bites from animals, particularly cats (however, this is not the same as cat-scratch disease).

Sporotrichosis is found worldwide, with the majority of cases reported in the tropical and subtropical regions of the Americas. In North America, sporotrichosis occurs most often in southern coastal regions and river valleys. Rose gardeners, farmers, miners, horticulturists, and armadillo hunters have an increased risk for infection. Patients with suggestive syndromes should be asked about occupational activities. S. schenckii can be isolated from soil, plants, or plant products. Infection may also occur during animal transmission and zoonotic transmission which is associated with scratches or bites from infected cats. Over the last two decades, Brazil has experienced an outbreak of cat-transmitted sporotrichosis in Rio de Janeiro, with 4,669 cases being reported ¹³⁾. Sporotrichosis can affect anyone regardless of age or gender as it depends on occupational exposure. In Uruguay, sporotrichosis is found more commonly in males and armadillo hunters; whereas, in India, it is more prevalent in females due to their greater involvement in agricultural work ¹⁴⁾.

Sporotrichosis pathophysiology

Sporothrix schenckii is a dimorphic fungus existing in hyphal form at temperatures less than 37 degrees and as a yeast at temperatures greater 37 degrees. Sporothrix schenckii is found on soil, marine animals, moss, wood, and decaying vegetation. A virulence factor is a feature of the organism that enhances microbial growth. Some virulence factors of Sporothrix schenckii include thermotolerance, ergosterol peroxide, and melanin ¹⁵⁾. The ergosterol peroxide found in the fungus is formed to evade reactive oxygen species during phagocytosis.

Sporotrichosis symptoms

The symptoms of sporotrichosis depend on where the fungus is growing. Contact your healthcare provider if you have symptoms that you think are related to sporotrichosis.

Sporotrichosis has an incubation period of several days to 3 months after exposure. Infections can be divided into several syndromes including cutaneous, pulmonary, and disseminated.

Sporotrichosis usually affects the skin or tissues underneath the skin. Cutaneous sporotrichosis arises from minor trauma of the fungus into the skin, which is most common in rose gardeners. The initial lesions are erythematous papulonodular lesions that may be smooth or verrucous and involve lymphatic channels ¹⁶⁾. The first symptom of cutaneous (skin) sporotrichosis is usually a small, painless bump that can develop any time from 1 to 12 weeks after exposure to the fungus. The bump can be red, pink, or purple, and it usually appears on the finger, hand, or arm where the fungus has entered through a break in the skin. The bump will eventually grow larger and may look like an open sore or ulcer that is very slow to heal. Additional bumps or sores may appear later near the original one. Lesions are typically painless even after ulceration. In this cutaneous sporotrichosis, the patient will not have systemic symptoms, and laboratory exams will be normal.

Pulmonary (lung) sporotrichosis is less common than the cutaneous (skin) form of the infection. Symptoms include cough, shorthess of breath, chest pain, and fever or weight loss. Risk factors include middle-aged men who have chronic pulmonary issues, abuse alcohol or have a history of steroid use, diabetes mellitus, sarcoidosis, and immunocompromised state ¹⁷⁾. Chest radiograph reveals unilateral or bilateral cavitary lesions, and if left untreated, the cavities gradually enlarge causing pulmonary dysfunction. Differential includes histoplasmosis, coccidiomycosis, and mycobacteria. Gram stain or sputum culture will help in diagnosis.

Symptoms of disseminated sporotrichosis depend on the body part affected. For example, infection of the joints can cause joint pain that may be confused with rheumatoid arthritis. Infections of the central nervous system can involve difficulty thinking, headache, and seizures. Disseminated sporotrichosis infections typically occur in immunocompromised patients. Widespread visceral dissemination occurs with lung abscess, liver and spleen involvement, and fungemia with spread to the esophagus, colon, bone marrow, and lymph nodes.

Sporotrichosis possible complications

People with a healthy immune system may have:

• Discomfort
• Secondary skin infections (such as staph or strep)

People with a weakened immune system may develop:

• Arthritis
• Bone infection
• Complications from medicines — amphotericin B can have serious side effects
• Lung and breathing problems (such as pneumonia)
• Brain infection (meningitis)
• Widespread (disseminated) disease

Sporotrichosis diagnosis

Sporotrichosis is typically diagnosed when your healthcare provider takes a small tissue sample (biopsy) of the infected area of the body. The sample is sent to laboratory for tests (usually a fungal culture) to find out what is causing the infection. Blood tests can help diagnose severe sporotrichosis, but they often can’t diagnose a cutaneous (skin) infection.

Definitive diagnosis is based in the culture, where one must demonstrate the dimorphism of the fungus. Diagnosis of cutaneous sporotrichosis can be made through direct examination of the specimen such as tissue biopsy or pus from lesions, while sputum culture aids in diagnosing pulmonary sporotrichosis. Diagnosis of disseminated sporotrichosis can be made from urine, blood, and synovial fluid analysis. Observation of yeast cells with potassium hydroxide might show the characteristic cigar-shaped buds or asteroid bodies. Other methods such as polymerase chain reaction (PCR) detection, enzyme-linked immunosorbent assay (ELISA) testing, antibody detection, and the sporotrichin skin test have been employed with no strong standardization in testing.

Sporotrichosis treatment

Most cases of sporotrichosis only involve the skin or the tissues underneath the skin. These infections are not life-threatening but must be treated with prescription antifungal medication for several months. The most common treatment for this type of sporotrichosis is itraconazole, taken by mouth for 3 to 6 months ¹⁸⁾. The dose varies from 100 to 200 mg/day orally for cutaneous forms, while a dose of 400 mg/day orally should be used for pulmonary forms. For children weighing up to 20 kg, 5 to 10 mg/kg/day is recommended ¹⁹⁾.

Supersaturated potassium iodide (SSKI) is another treatment option for cutaneous (skin) sporotrichosis. However, supersaturated potassium iodide and azole drugs like itraconazole should not be used during pregnancy.

Patients with severe forms of sporotrichosis such as disseminated and pulmonary forms, particularly in those patients with an immunocompromised state are usually treated with amphotericin B, which is given through a vein. Itraconazole is often used after the initial treatment with amphotericin B, for a total of at least 1 year of antifungal treatment. People with sporotrichosis in the lungs may also need surgery to cut away the infected tissue.

Infectious Diseases Society of America Guidelines for the management of patients with sporotrichosis

Lymphocutaneous and Cutaneous Sporotrichosis

1. For cutaneous and lymphocutaneous sporotrichosis, itraconazole 200 mg orally daily is recommended to be given for 2–4 weeks after all lesions have resolved, usually for a total of 3–6 months ²⁰⁾.
2. Patients who do not respond should be given a higher dosage of itraconazole (200 mg twice daily); terbinafine, administered at a dosage of 500 mg orally twice daily; or saturated solution of potassium iodide (SSKI), initiated at a dosage of 5 drops (using a standard eye-dropper) 3 times daily and increasing, as tolerated, to 40–50 drops 3 times daily ²¹⁾.
3. Fluconazole (400–800 mg daily) should be used only if the patient cannot tolerate these other agents.
4. Local hyperthermia can be used for treating patients, such as pregnant and nursing women, who have fixed cutaneous sporotrichosis and who cannot safely receive any of the previous regimens .

Osteoarticular Sporotrichosis

1. Itraconazole, administered at 200 mg orally twice daily for at least 12 months, is recommended ²²⁾.
2. Amphotericin B, given as a lipid formulation at a dosage of 3–5 mg/kg daily, or amphotericin B deoxycholate, administered at a dosage of 0.7–1.0 mg/kg daily, can be used for initial therapy. After the patient has shown a favorable response, therapy can be changed to itraconazole administered at a dosage of 200 mg orally twice daily to complete a total of at least 12 months of therapy.
3. Serum levels of itraconazole should be determined after the patient has been receiving this agent for at least 2 weeks to ensure adequate drug exposure.

Pulmonary Sporotrichosis

1. For severe or life-threatening pulmonary sporotrichosis, amphotericin B, given as a lipid formulation at 3–5 mg/kg daily, is recommended ²³⁾. Amphotericin B deoxycholate, administered at a dosage of 0.7–1.0 mg/kg daily, could also be used.
2. After the patient has shown a favorable response to amphotericin B, therapy can be changed to itraconazole (200 mg orally twice daily) to complete a total of at least 12 months of therapy.
3. For less severe disease, itraconazole administered at 200 mg orally twice daily for at least 12 months is recommended.
4. Serum levels of itraconazole should be determined after the patient has been receiving this agent for at least 2 weeks to ensure adequate drug exposure.
5. Surgery combined with amphotericin B therapy is recommended for localized pulmonary disease.

Meningeal Sporotrichosis

1. Amphotericin B, given as a lipid formulation at a dosage of 5 mg/kg daily for 4–6 weeks, is recommended for the initial treatment of meningeal sporotrichosis ²⁴⁾. Amphotericin B deoxycholate, administered at a dosage of 0.7–1.0 mg/kg daily, could also be used but was not preferred by the panel.
2. Itraconazole (200 mg twice daily) is recommended as step-down therapy after the patient responds to initial treatment with amphotericin B and should be given to complete a total of at least 12 months of therapy.
3. Serum levels of itraconazole should be determined after the patient has been receiving this agent for at least 2 weeks to ensure adequate drug exposure.
4. For patients with AIDS and other immunosuppressed patients, suppressive therapy with itraconazole at a dosage of 200 mg daily is recommended to prevent relapse.

Disseminated (Systemic) Sporotrichosis

1. Amphotericin B, given as a lipid formulation at a dosage of 3–5 mg/kg daily, is recommended for disseminated sporotrichosis ²⁵⁾. Amphotericin B deoxycholate (0.7–1.0 mg/kg daily) could also be used but was not preferred by the panel.
2. Itraconazole (200 mg twice daily) is recommended as step-down therapy after the patient responds to initial treatment with amphotericin B and should be given to complete a total of at least 12 months of therapy.
3. Serum levels of itraconazole should be determined after the patient has been receiving this agent for at least 2 weeks to ensure adequate drug exposure.
4. Lifelong suppressive therapy with itraconazole (200 mg daily) may be required for patients with AIDS and other immunosuppressed patients if immunosuppression cannot be reversed.

Sporotrichosis in Pregnant Women and in Children

1. Amphotericin B, given as a lipid formulation at a dosage of 3–5 mg/kg daily, or amphotericin B deoxycholate, given at a dosage of 0.7–1 mg/kg daily, is recommended for severe sporotrichosis that must be treated during pregnancy; azoles should be avoided ²⁶⁾.
2. Local hyperthermia can be used for the treatment of cutaneous sporotrichosis in pregnant women.
3. Itraconazole, administered at a dosage of 6–10 mg/kg to a maximum of 400 mg orally daily, is recommended for children with cutaneous or lymphocutaneous sporotrichosis.
4. An alternative for children is SSKI initiated at a dosage of 1 drop (using a standard eye-dropper) 3 times daily, increasing, as tolerated, up to a maximum of 1 drop per kg of body weight or 40–50 drops 3 times daily, whichever is lowest.
5. For children with disseminated sporotrichosis, amphotericin B (0.7 mg/kg daily) should be the initial therapy, followed by itraconazole (6–10 mg/kg, up to a maximum of 400 mg daily) as step-down therapy.

Sporotrichosis prognosis

With treatment, full recovery is likely. Disseminated sporotrichosis is more difficult to treat and requires several months of therapy. Disseminated sporotrichosis can be life threatening for people with a weakened immune system.