WAIKOLOA, HAWAII – Toenail onychomycosis is a common condition in the general population, but it’s three- to fourfold more prevalent in certain at risk populations where it can have serious and even life-threatening consequences, Dr. Theodore Rosen observed at the Hawaii Dermatology Seminar provided by the Global Academy for Medical Education/Skin Disease Education Foundation.
He cited a recent systematic review led by Dr. Aditya K. Gupta, professor of dermatology at the University of Toronto, whom Dr. Rosen hailed as one of the world’s great fungal disease authorities. Dr. Gupta and coworkers concluded that while the prevalence of dermatophyte toenail onychomycosis is 3.2% worldwide in the general population, it climbs to 8.8% in diabetics, 10.2% in psoriatics, 10.3% in the elderly, 11.9% in dialysis patients, 5.2% in renal transplant recipients, and 10.4% in HIV-positive individuals. The highest prevalence of onychomycosis due to non-dermatophyte molds was seen in psoriasis patients, at 2.5%, while elderly patients had the highest prevalence of onychomycosis caused by yeasts, at 6.1% (J Eur Acad Dermatol Venereol. 2015 Jun;29:1039-44).
“Onychomycosis is especially important in those who are immunocompromised and immunosuppressed, for two reasons. One is that really odd organisms that aren’t Trichophyton rubrum or T. interdigitale can be involved: saprophytes like Scopulariopsis, Acremonium, Aspergillus, and Paecilomyces. And some of these saprophytes, like Fusarium, can get from the nail and nail bed into the bloodstream and can kill,” explained Dr. Rosen, professor of dermatology at Baylor College of Medicine in Houston.
“Onychomycosis, aside from the fact that it looks bad and often leads to pain, can also lead to breaks in the skin which then result in secondary bacterial infections. In fact, after motor vehicle accidents, onychomycosis and tinea pedis combined are the most common cause of lower extremity cellulitis leading to hospitalization in the United States,” he continued.
The go-to treatments for onychomycosis in patients with a bad prognostic factor are oral itraconazole (Sporanox) and terbinafine. Don’t be unduly swayed by the complete cure rates reported in clinical trials and cited in the product package inserts; they don’t tell the full story because of important differences in study design, according to Dr. Rosen.
He recommended that physicians familiarize themselves with posaconazole (Noxafil) as an antifungal to consider for second-line therapy in difficult-to-cure cases of onychomycosis in immunosuppressed patients. This is off-label therapy. The approved indications for this triazole antifungal agent are prophylaxis of invasive Aspergillus and Candida infections in severely immunocompromised patients, as well as treatment of oropharyngeal candidiasis. But this is a potent agent that provides broad-spectrum coverage coupled with a favorable safety profile. It performed well in a phase IIb randomized, placebo- and active-controlled, multicenter, investigator-blinded study of 218 adults with toenail onychomycosis (Br J Dermatol. 2012 Feb;166:389-98).
Dr. Rosen reported serving on scientific advisory boards for Anacor, Merz, and Valeant.
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