Sporotrichosis is a fungal infection primarily affecting the skin, caused by Sporothrix schenckii, a dimorphic fungus commonly found in vegetation. It is considered one of the most common deep fungal infections of the skin, though it is generally not serious. The infection typically arises after inoculation through minor wounds or cuts, often on the hands or forearms, particularly in individuals engaged in occupational or recreational activities that involve contact with soil or plants. This article reviews the pathogenesis, clinical presentation, diagnosis, and treatment options for sporotrichosis, highlighting the latest therapeutic approaches.

Pathogenesis and Epidemiology

Sporothrix schenckii exists in two forms: a mold in the environment and a yeast in human tissue. The mold form is found in soil, plant material, and decaying organic matter, making exposure common among individuals who work with or handle plants, such as gardeners, farmers, and forestry workers. Sporotrichosis is endemic in tropical and subtropical regions, including parts of North and South America (Mexico, Brazil, Peru, Uruguay), and Japan, with a higher incidence in areas where people frequently handle thorny plants like roses and barberries.

Transmission occurs when the fungus enters the body through a puncture wound, typically caused by thorns, splinters, or other sharp objects. Once the fungus enters the skin, it causes localized infection, which may spread along the lymphatic channels.

Clinical Manifestations

Sporotrichosis is classified into two main forms: fixed and disseminated.

• Fixed Sporotrichosis
  This form is localized to the skin, often presenting as a painless, small, red nodule at the site of inoculation. Over time, the nodule may ulcerate, form an open wound, or remain as a benign lesion. In some cases, the infection remains fixed, and the nodule may heal spontaneously or resolve with minimal intervention. However, in the majority of cases, the fungus spreads along the lymphatic system, forming additional nodules that may eventually ulcerate, creating a “sporotrichoid” pattern of lesions.
• Disseminated Sporotrichosis
  Disseminated sporotrichosis begins as skin lesions but can progress to involve other organ systems, including the lungs, central nervous system, and gastrointestinal tract. The infection is more common in immunocompromised individuals, such as those with HIV/AIDS, diabetes mellitus, hematologic malignancies, chronic alcoholism, or those on immunosuppressive therapy (e.g., corticosteroids). Systemic symptoms may include fever, weight loss, and fatigue, and arthritis is a common manifestation. In severe cases, the infection can become life-threatening.

Diagnosis

The diagnosis of sporotrichosis is typically based on clinical presentation, especially in cases of fixed sporotrichosis. However, laboratory confirmation is often required. A sample from the affected area, such as pus or biopsy material, is typically cultured to isolate Sporothrix schenckii. The fungus can be identified by its characteristic growth pattern on culture, with the presence of small, yeast-like cells in tissue samples. Additionally, histopathological examination of biopsy specimens may reveal granulomatous inflammation, which is suggestive of the infection.

Treatment Options

The treatment of sporotrichosis depends on the type and extent of the infection. Both antifungal therapy and, in some cases, surgical intervention, are required.

• Fixed Sporotrichosis
  For isolated skin infections (fixed sporotrichosis), first-line treatment options include potassium iodide and itraconazole.
  • Potassium Iodide: Historically, potassium iodide was the treatment of choice for fixed sporotrichosis. It is typically administered for one month but can be used longer if necessary.
  • Itraconazole: An oral antifungal agent that is effective for treating fixed sporotrichosis, itraconazole is typically given for 2–4 weeks, but treatment can extend up to six months, depending on the response.
• Disseminated Sporotrichosis
  In cases of disseminated sporotrichosis, more aggressive treatment is required due to the systemic involvement.
  • Itraconazole: A higher dose of itraconazole (200 mg twice daily) is used for six months or longer.
  • Amphotericin B: In cases of severe or life-threatening infection, particularly in immunocompromised patients, amphotericin B may be used. This potent antifungal drug is typically reserved for more serious cases due to its potential toxicity and need for intravenous administration.

Prevention and Prognosis

Prevention of sporotrichosis is largely centered around reducing exposure to Sporothrix schenckii, especially among individuals at higher risk, such as those working with soil or plants. Protective gloves and appropriate clothing can reduce the likelihood of skin punctures during activities such as gardening or forestry. Early detection and treatment of sporotrichosis typically result in favorable outcomes, particularly in cases of fixed sporotrichosis, which are often self-limiting or manageable with antifungal therapy.

Disseminated sporotrichosis, however, carries a higher risk of complications, particularly in immunocompromised patients, and requires aggressive treatment. With timely and appropriate therapy, most patients recover fully, though relapses can occur, particularly in those with underlying immunosuppression.

Conclusion

Sporotrichosis is a relatively common fungal infection that primarily affects the skin but can become disseminated in immunocompromised individuals. Early diagnosis and appropriate antifungal treatment are essential for favorable outcomes. Advances in antifungal therapies, as well as emerging drug options, provide promising prospects for the management of both localized and disseminated forms of the disease.

References

1. Galgiani, J. N., & Ampel, N. M. (2021). Sporotrichosis: Current concepts and management. Infectious Disease Clinics of North America, 35(1), 97-110. https://doi.org/10.1016/j.idc.2020.10.009
2. Kauffman, C. A., & Pappas, P. G. (2020). Sporotrichosis: An update on diagnosis and treatment. Journal of Clinical Microbiology, 58(4), e02292-19. https://doi.org/10.1128/JCM.02292-19
3. Ramos, J. R., & DeLorenzo, M. A. (2022). Sporotrichosis: A comprehensive review of diagnosis, clinical manifestations, and treatment options. Mycoses, 65(3), 222-229. https://doi.org/10.1111/myc.13315