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Nail infections due to mold are difficult to treat: consider sequential therapy.

LAS VEGAS -- Onychomycosis caused by nondermatophytic mold infection is on the rise worldwide, and it's the culprit in an estimated 16% of cases that Dr. Antonella Tosti sees in her Bologna, Italy-based dermatology practice.

Suspect mold as the cause of the infection when your patient presents with proximal subungual onychomycosis with inflammation.

"The clinical picture is always the same," Dr. Tosti said at the annual meeting of the Pacific Dermatologic Association. 'Another feature is deep white superficial onychomycosis."

In her clinical experience, Fusarium species and Scopulariopsis brevicaulis are the two most common molds that cause onychomycosis. "Keep in mind that you have to tell the patient that these two molds are very difficult to eradicate," said Dr. Tosti, professor of dermatology at the University of Bologna.

While she has no explanation for the increase in the prevalence of nondermatophytic mold infections," it may just be a better skill in the diagnosis," she told this newspaper.

Dermatophytes account for more than 85% of onychomycosis, with Trichophyton rubrum being the most common pathogen. They may produce four different clinical types of onychomycosis, depending on the way the fungus invades the nail:

* Distal subungual onychomycosis. In this type, dermatophytes reach the nail bed horny layer through the hyponychium. Affected nails show subungual hyperkeratosis, onycholysis, and yellow discoloration. This type affects toenails more often than fingernails. Because skin of the palms and soles is the primary site of infection, distal subungual onychomycosis is usually associated with tinea manuum or tinea pedis.

* Proximal subungual onychomycosis. This clinical type is characterized by a primitive invasion of the nail matrix keratogenous zone through the proximal nail fold horny layer. Fungal elements are typically located in the ventral nail plate with minimal inflammatory reaction. Affected nails show proximal leukonychia that progresses distally with nail growth. Dr. Tosti noted that when T. rubrum is the cause of the infection, "you should look for HIV, because it is mostly seen in immunocompromised patients."

* White superficial onychomycosis. In this type, dermatophytes colonize the most superficial layers of the nail plate without penetrating it. Affected nails contain multiple friable white opaque spots that can be easily scraped away. "This is a superficial infection, but sometimes the infection may be deeper," she said. "When you see a deep white superficial onychomycosis, you should think of mold or HIV [as the culprit]."

* Endonyx onychomycosis. This type is characterized by massive nail plate parasitization in the absence of nail bed inflammatory changes. The affected nail is milky white in color, the nail plate is firmly attached to the nail bed, and there is no nail bed hyperkeratosis or onycholysis.

Topical antifungal treatment with amorolfine 5% nail lacquer and ciclopirox 8% nail lacquer--which are not currently available in the United States but are available in most European countries--is effective as monotherapy in the treatment of white superficial onychomycosis and of distal subungual onychomycosis limited to the distal nail of a few digits. The recommended treatment is amorolfine once weekly or ciclopirox once daily for 6-12 months. Dr. Tosti said that nail lacquers also are used in severe onychomycosis in combination with systemic antifungals to reduce duration of treatment and increase the cure rate.

Systemic treatment with terbinafine or itraconazole produces mycologic cure in more than 90% of fingernail infections and in about 80% of toenail infections. Dr. Tosti finds that adding topical antifungals can increase these success rates.

She recommends that terbinafine be administered at a dosage of 250 mg/day or as "pulse therapy" at a dose of 500 mg/day for 1 week per month, while itraconazole should be administered as pulse therapy at a dose of 400 mg/day for 1 week per month. Treatment duration is 2 months for fingernails and 3-4 months for toenails.

Dr. Tosti noted that data about the efficacy of fluconazole for treating onychomycosis "are recent and require additional studies to definitely establish optimal dosages and treatment duration." The approved dosage of fluconazole is 150 mg/week, but dosages up to 300 mg/week "are probably more effective," she said. In any case, treatment should last at least 6 months.

Sequential treatment with itraconazole and terbinafine has been used to improve cure rates, she added. The suggested regimen is two pulses of itraconazole 400 mg/day for 1 week per month, followed by 1-2 pulses of terbinafine 500 mg/day for 1 week per month.

Mycologic cure can be evaluated at the end of treatment. Evaluation of clinical response, however, requires several months due to the slow growth rate of the nail. Up to 20% of "cured" patients may experience recurrences and/or reinfection.

Systemic antifungals are effective in treating onychomycosis due to Aspergillus species, Scopulariopsis brevicaulis, and Fusarium species. "These molds are difficult to treat and should always be associated with nail lacquers," Dr. Tosti said, adding that nail infections caused by Candida are almost always a sign of immunosuppression.
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Title Annotation:Clinical Rounds
Author:Brunk, Doug
Publication:Family Practice News
Geographic Code:4EUIT
Date:Oct 1, 2003
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