Sporotrichosis

Sporotrichosis is a subcutaneous fungal infection caused by Sporothrix species, most often Sporothrix schenckii sensu lato. It is a dimorphic fungus: mold in the environment, yeast in tissue at body temperature.

Transmission occurs through traumatic implantation of environmental material such as thorns and wood splinters. Occupations involving soil and plant matter are at risk; cat-associated zoonotic transmission has been reported. Pulmonary infection is rare.

Clinical forms include cutaneous sporotrichosis (often a small ulcer at the entry site) and the lymphocutaneous form with nodules along draining lymphatics. Immunocompromised patients may develop disseminated or extracutaneous disease; ocular and pulmonary forms are uncommon.

Diagnosis relies on culture of the organism from lesions, which shows mold at ambient temperature and yeast at 37 C; histopathology and molecular tests can help; serology is supportive but not definitive.

First-line treatment is itraconazole for several months (commonly 3–6 months), longer for disseminated disease. Alternatives include saturated potassium iodide in resource-limited settings; amphotericin B for severe disseminated disease or CNS involvement.

Prognosis is favorable with treatment; relapse is possible but uncommon. Prevention emphasizes protective clothing and prompt wound care after injuries, and awareness of cat-associated transmission in endemic areas.