New Orleans — Dermatologists practicing medicine in tropical regions frequently treat fungal infections such as sporotrichosis, mycetoma and chromoblastomycosis — ailments that practitioners in temperate regions rarely encounter, according to Oliverio Welsh, M.D., emeritus professor, department of dermatology, Universidad Aut?noma de Nuevo Le?n, Monterrey, Mexico. Superficial skin infections are the most common fungal infections, but subcutaneous infections, known as deep mycosis or, in rare cases, disseminated fungal disease, may also occur.
New Orleans -Dermatologists practicing medicine in tropical regions frequently treat fungal infections such as sporotrichosis, mycetoma and chromoblastomycosis - ailments that practitioners in temperate regions rarely encounter, according to Oliverio Welsh, M.D., emeritus professor, department of dermatology, Universidad Autónoma de Nuevo León, Monterrey, Mexico. Superficial skin infections are the most common fungal infections, but subcutaneous infections, known as deep mycosis or, in rare cases, disseminated fungal disease, may also occur.
Sporotrichosis Sporotrichosis is a chronic granulomatous disease that primarily affects the skin and lymphatic vessels. The infectious agent is Sporothrix schenckii, a dimorphic fungus often present in soil and on plants, such as roses. Infection can occur when the fungus enters through a break in the skin. For example, rose gardeners may become infected following a minor injury from a thorn. Skin lesions are generally painless.
In rare cases involving the joints and the lung, amphotericin B can be used. Women who are pregnant or breast feeding should not be given potassium iodide treatment. For these patients, thermotherapy is an appropriate therapy for the localized cutaneous forms of sporotrichosis.
Mycetoma Mycetoma refers to disease caused either by true fungi (eumycetomas) or by aerobic actinomycetes (actinomycetomas). Farmers are among the most likely to get cutaneous mycetoma, which can present as a firm swelling of the affected site, with abscesses and fistula.
"Purulent exudates that drain from the abscesses and fistula contain the granules of the infecting organism," Dr. Welsh says.
True fungi (eumycetes) that commonly cause eumycetoma include Scedosporium apiospermum, Madurella mycetomatis, Madurella grisea and Acremonium spp. Terbinafine and triazoles are standard treatments for eumycetoma, often combined with surgery of the infecting tissue in refractory cases.
"In isolated cases, posaconazole and voriconazole have been reported to be beneficial," Dr. Welsh adds.
Nocardia brasiliensis is the most common cause of actinomycetomas in Mexico and Central America.
"For conventional treatment of actinomycetoma, the antimicrobial of choice is sulfamethoxazole-trimethoprim (SXT) given orally, 40/8 mg/kg/day, for a period from six months to more than a year," Dr. Welsh says. In cases resistant to treatment, adding amikacin may be effective.
Coccidioidomycosis Coccidioidomycosis is a systemic infection usually arising from inhalation of spores of the dimorphic fungus Coccidioides immitis. Clinical symptoms vary.
"When lung is involved, symptoms might include productive cough, bloody sputum, fever, asthenia and weight loss. There are neurological symptoms in cases with CNS involvement," Dr. Welsh says. Cutaneous manifestations of systemic infection can occur, presenting as abscesses, ulcers, verrucous plaques, papules and nodules. Primary inoculation through the skin is rare.
Most cases of coccidioidomycosis infections are self-resolving. When treatment is required, triazoles, such as itraconazole or fluconazole, are usually given for one to two years. Alternatively, amphotericin B could be given, either alone or in lipophilic complexes, until the infection resolves or side effects lead to treatment discontinuation.
Chromoblastomycosis Chromoblastomycosis is an infection caused by dematiaceous fungi such as Fonsecaea pedrosoi, Cladophialophora carrionii and Phialophora verrucosa. Cases are rarely seen in temperate climates.
"This disease predominates in Central and South America," Dr. Welsh says.
The slow-growing cutaneous lesions initially appear as small, asymptomatic papules or nodules on the lower extremities. Mycological examination is necessary for the identification of the infecting fungus.