Sporotrichosis is an infection of your skin caused by a fungus, Sporothrix schenckii. This infection-causing fungus is related more closely to the mold on stale bread or the yeast used to brew beer than to bacteria that usually cause infections. The mold is found on rose thorns, hay, sphagnum moss, twigs, and soil. Therefore, the infection is more common among
gardeners who work with roses, moss, hay, and soil.
Persons handling thorny plants, sphagnum moss, or baled hay are at increased risk of developing sporotrichosis. Outbreaks of sporotrichosis have occurred among nursery workers handling sphagnum moss, rose gardeners, children playing on baled hay, and greenhouse workers handling bayberry thorns that are contaminated by the fungus. A number of cases have recently occurred among nursery workers, especially workers handling sphagnum moss topiaries.
Sporotrichosis is acquired through direct inoculation into the skin and rarely via inhalation of conidia. As a consequence, the majority of cases are localized lesions affecting the skin and subcutaneous tissues with minimal if any systemic manifestation. Skin lesions characteristically follow lymphatic pathways, but the lymph nodes themselves are not usually involved. The initial erythematous papulonodular lesions evolve into either smooth or verrucose painless nodules of about 3 cm that may ulcerate and drain. There is also a clinical variety called "the fixed form". The most common form of extracutaneous sporotrichosis is osteoarthritis. Pulmonary sporotrichosis has also been described. Disseminated forms of disease are seen on occasion, and these classically affect immunosuppressed individuals. With the advent of the HIV epidemic the frequency of this presentation has increased.
The first sign of sporotrichosis is usually a small painless bump resembling an insect bite. It can be red, pink, or purple in color. The bump (nodule) usually appears on the finger, hand, or arm where the fungus first entered through a break on the skin. This is followed by one or more additional bumps or nodules which open. They may look like boils. Eventually, the bumps turn into open hollowed-out sores (ulcerations), which are very slow to heal. The infection can also spread to other areas of the body.
Treatment of sporotrichosis depends on the site infected.
Infections in the skin only: These infections have traditionally been treated with saturated potassium iodide solution. This medicine is given 3 times per day for 3-6 months until all the lesions have gone away. Skin infections may also be treated with itraconazole (Sporanox) for up to 6 months.
Infection in the bones and joints: These infections are much more difficult to treat and rarely respond to potassium iodide. Itraconazole is often used as an initial medication for several months or even up to a year. Amphotericin is also used, but this medicine can only be given through an IV. It has more side effects and may still need to be given for many months. Surgery is sometimes needed to remove infected bone.
Infection in the lungs: Lung infections are treated with potassium iodide, itraconazole, and amphotericin with varying amounts of success. Sometimes the infected areas of the lung have to be removed.
Infection in the brain: Sporotrichosis meningitis is very rare, so there is not much information on treatment. Amphotericin plus 5-fluorocytosine is generally recommended, but itraconazole might also be tried.