Is onychomycosis a fungal nail infection caused by dermatophytes, nondermatophytes, and yeast that can be treated with topical treatments?

From the Guidelines

Yes, onychomycosis is a fungal nail infection caused by dermatophytes, nondermatophytes, and yeasts that can be treated with topical treatments. Onychomycosis is a difficult-to-treat infection, but recent experience and knowledge have been gained using topical treatments, which work by disrupting fungal cell membranes or inhibiting essential fungal enzymes 1. Topical treatments are most effective for mild to moderate cases, particularly those affecting less than 50% of the nail or limited to the distal edge. Common topical medications include efinaconazole 10% solution, which has been found to be effective in treating onychomycosis, with mycological cure rates approaching 50% and complete cure in 15% of patients after 48 weeks of application 1.

Some key points to consider when using topical treatments for onychomycosis include:

• The infected portion of the nail should be trimmed and filed regularly to improve medication penetration
• Patients should keep nails dry, wear breathable footwear, and avoid sharing nail tools
• Topical treatments generally have fewer side effects than oral antifungals but require longer treatment duration and may be less effective for severe infections involving the nail matrix or multiple nails
• In such cases, oral antifungals like terbinafine or itraconazole might be necessary, particularly for nondermatophyte moulds, which can be difficult to eradicate 1
• Complete cure can take 9-12 months as the healthy nail needs time to grow out fully

It's also important to note that other topical treatments, such as amorolfine 5% nail lacquer, have been shown to be effective in treating onychomycosis, with clinical improvement obtained in around 50% of cases of distal fingernail and toenail onychomycosis 1. However, the clinical improvement obtained with topical antifungals may not always be synonymous with mycological cure, which can have lower rates.

From the FDA Drug Label

Onychomycosis is a fungal infection of the nails that can be caused by various fungi, including dermatophytes, non-dermatophytes, and yeast. The statement that onychomycosis is a fungal nail infection caused by dermatophytes, nondermatophytes, and yeast is true.

• The causative organisms of onychomycosis include:
  • Dermatophytes
  • Non-dermatophytes
  • Yeast Topical treatments, such as ciclopirox, can be used to treat onychomycosis, and they work by disrupting fungal cell membranes or inhibiting essential fungal enzymes 2. However, it may take months to show results as healthy nail must grow out to replace infected portions. The optimal clinical effect is seen some months after mycological cure and cessation of treatment due to the time period required for outgrowth of healthy nail 3.

From the Research

Causes of Onychomycosis

• Onychomycosis is a fungal nail infection caused by dermatophytes, nondermatophytes, and yeast, as stated in studies 4, 5, 6, 7.
• Dermatophytes are the most frequently implicated causative agents in onychomycosis, while yeasts and nondermatophyte molds are also recognized as pathogens 5, 6, 7.

Treatment of Onychomycosis

• Topical treatments provide an alternative modality to oral antifungal treatments, bypassing the systemic effects of oral drugs, and recent research has centered on topical drug improvement and development 4.
• Topical treatments work by disrupting fungal cell membranes or inhibiting essential fungal enzymes, but may take months to show results as healthy nail must grow out to replace infected portions.
• Oral terbinafine pulse therapy is an effective and safe alternative in the treatment of onychomycosis due to dermatophytes, and combination therapy with topical ciclopirox or amorolfine may be used 6.
• Lasers may be a potential management option for older patients and onychomycosis patients with coexisting conditions, but their effectiveness as a therapeutic intervention is limited based on complete, mycologic, and clinical cure rates 7.

Efficacy of Treatments

• Clinical cure rates and mycological cure rates vary depending on the treatment used, with oral terbinafine pulse therapy showing clinical cure rates of 71.73-82.60% and mycological cure rates of 88.9-100% in some studies 6.
• Laser monotherapy for dermatophyte onychomycosis has limited efficacy, with combined clinical cure rates of 13.0-25.9% and no reported complete cure rates 7.