Sporotrichosis

Description

• Subacute or chronic fungal infection due to Sporothrix schenckii
• Most frequent; least severe deep mycosis
• Typically presents as pustules or papules that progress to form a subcutaneous nodules with ulceration and purulent drainage; untreated, the fungus can spread via local lymphatics.
• Occurs in the following forms:
  • Cutaneous/lymphocutaneous (most common)
  • Disseminated
    • Osteoarticular (80% of extracutaneous disease), testicular/penile, meningeal, ocular (rare); pulmonary
• Most likely to occur in gardeners, farmers, and horticulturists
• System(s) affected: skin/exocrine, hematologic/lymphatic/immunologic, musculoskeletal, renal, respiratory
• Synonym(s): Schenck disease; rose gardener disease

Epidemiology

Incidence

• ~<1/100,000 persons per year; not reportable (1)
• Worldwide occurrence: most prevalent in temperate climates; endemic in Japan, India, Central and South America (1)
• Most U.S. cases from the Mississippi River Valley (1)

Etiology and Pathophysiology

• S. schenckii is a dimorphic aerobic fungus that exists in hyphal form at temperatures <37°C and as yeast >37°C; the organism is a ubiquitous saprophyte found on soil, sphagnum moss, wood, marine animals, and decaying vegetation.
• Thermotolerance allows the fungus to grow at 37°C.
• Virulence factors include melaninogenica and ergosterol peroxide. Surface lipids impede phagocytosis, and the organism has the ability to adhere to epithelium and endothelium (1).
• Lymphocutaneous infection: Primary lesion forms 3 weeks to 6 months after traumatic inoculation into the skin and spreads along lymphatic channels.
• Disseminated sporotrichosis: hematogenous spread
• Pulmonary diseases: inhalation of spores (conidia)

Risk Factors

• Contact with soil, mulch, sphagnum moss, pine needles, hay, timber, or thorny plants (rose bushes)
• Occupational activities: gardeners, florists, horticulturists, landscapers, carpenters, farmers, fishermen, miners, veterinarians or other animal handlers—especially cats, armadillos, and squirrels
• Immunocompromised patients (e.g., HIV, hematologic malignancy); chronic obstructive pulmonary disease, alcoholism, and diabetes mellitus increase risk of disseminated disease.

General Prevention

• Wear gloves and long sleeves when handling soil or other high-risk plant materials.
• Avoid contact with infected animals.