Sporotrichosis B42.8

A subacute or chronic infectious disease of the cutis and hypodermis occurring worldwide, which has become very rare in Europe but relatively common in developing countries, caused by pathogens of the Sporotrix schenkii complex (dimorphic fungi). Also commonly referred to as injury mycosis.

The dimorphic fungus Sporothrix schenckii (Sporotrichon schenckii) is a soil saprophyte that lives in a climate with an average temperature of 20-25C° on rotting wood and dying plants. In this respect, the infection occurs mainly in rural populations.

Besides Sporothrix schenckii sensu stricto, the Sporotrichon complex includes 4 other species:

• S. albicans
• S. brasiliensis
• S. globosa
• S. mexicana

Animals also represent a reservoir of pathogens. Starting from dogs, cats, horses, muskrats, pigs, birds, reptiles, infection can occur through scratch or bite injuries (zoonosis).

A distinction is made according to the form of propagation:

• Fixed cutaneous form
• Lympho-cutaneous form
• Mucocutaneous form
• Disseminated form.

Worldwide. North America, Japan, mainly tropics and subtropics, only sporadically in Europe. The only epidemic to date occurred in South Africa in the mid-20th century among mine workers who became infected with mine timber (infested with Sporothrix schenckii).

Occurs mainly with gardeners, farmers or fishermen. Common and complicating in immunocompromised individuals.

Hands and feet, rarely face, only very occasionally trunk and back.

Incubation period: days to months after a frequently unnoticed injury (injury mycosis: e.g., thorn injury - in American: rose gardener's disease). (e.g. thorn injury - in American: rose gardener's disease), multiple, bluish-red or brown, 0.2-10.0 cm large, smooth or scaly, sometimes also verrucous papules, plaques and nodules with a tendency to ulceration or with discharge of purulent secretion form in a lymphogenically transmitted infection, usually with few symptoms, arranged in chains along the lymphatic channels (lymphogenic spread). The skin lesions may coalesce into planar nodular conglomerates.

In the fixed cutaneous form, isolated, 1.0-6.0 cm (or larger), minimally symptomatic, verrucous plaques, nodules, or ulcers with peripherally accentuated marginal rims are found at the site of entry and progress centrifugally if untreated.

Infestation of the musculature and bones is possible but rather rarely described, and occurs mainly in immunosuppression.

Mixed-cell inflammatory reaction of the dermis with lymphocytes, granulocytes, histiocytes and plasma cells Occasionally smaller and larger abscesses. With increasing duration of the infection an increasing granulomatous inflammatory character develops with histiocytes, plasma cells and giant cells. In HE sections, so-called "asteroid bodies" can be detected in approx. 30% of cases. These consist of one or more fungal cells in the centre surrounded by a ring of spine-like, red, eosinophilic extensions (see Splendore-Hoeppli phenomenon). Fungal cells are usually only found in the acute phase of infection. The cells of S. schenckii are 2-10 µm in size in the tissue, both yeast-like round to oval, and elongated (the elongated elements are also called "cigar bodies"). Detection by Grocott staining is recommended.

Clinic with lymphogenic arrangement of the lesions.

Histology: often multiple sampling is necessary to detect the pathogens.

Easy cultivation of the pathogen at room temperature from smear of secretion or biopsy. Flower-like arranged conidia on hyphal stems (margarite forms) occur.

Tuberculosis cutis luposa; syphilis; cutaneous leishmaniasis; chromomycosis; nocardiosis; ecthymata;

Itraconazole (e.g. Sempera) 400-600 mg/day p.o. over at least 6 weeks; to prevent recurrence, 100-200 mg are given over several months (guidelines of the American Society for Infectious Diseases). Itrakonazole has proven to be highly effective.

In extracutaneous forms: Amphotericin B 0.1 mg/kg bw/day, increasing to 1.0 mg/kg bw as an infusion.

Alternatively Terbinafine: The clinical efficiency could be shown in 2 studies (dosage: 500 mg/day p.o.). Long-term therapy 250mg/day p.o. up to 42 weeks.

Alternative Ketoconazole: The results of the ketoconazole therapy were rather disappointing, only single cases showed a response.

Remark: Previously, potassium iodide therapy was the treatment of choice: Potassium iodide is applied in the form of a saturated aqueous solution. The initial dose is 0.5-1.0 ml 3 times/day p.o. and is increased dropwise to a total dose of 3-6 ml 3 times/day. The mixture is more palatable if it is given together with milk. The therapy should be given one month beyond clinical remission.

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