Molecular testing for onychomycosis with Diagnostiki Athinon’s NailScan® is used to confirm the diagnosis (antifungal treatment will not be successful if there is another cause for the nail condition) and to identify the responsible organism (yeasts may require different treatment from dermatophytic fungi).
More Information
Superficial fungal infections represent the most frequent clinical presentation of human mycosis, affecting approximately 20–25% of the world’s population. The main etiological agents are dermatophytes, including Trichophyton rubrum and Trichophyton interdigitale. However, yeasts (especially Candida albicans) and non-dermatophyte fungi can also cause onychomycosis. The prevalence of onychomycosis varies by country and the methodology used for laboratory testing, but is estimated to be between 8 and 14%.
Laboratory diagnosis of fungal infections of the skin and its appendages (skin, nails) is currently based on microscopy and culture tests, although these methods have low to moderate sensitivity. Conventional nail microscopy using 20% potassium hydroxide (KOH) has a low sensitivity of 40–68%, which can be somewhat increased with the use of fluorescence. Cultures, which are widely used in clinical laboratories as reference tests, remain negative in 20-30% of positive microscopy cases and also have a prolonged turnaround time.
The whole process is time-consuming, requiring 10 to 15 days, sometimes up to 3 and 4 weeks, and the accuracy depends on the expertise of the personnel. The introduction of methodology based on the molecular technique PCR can increase the sensitivity, specificity, and speed, and potentially even reduce the cost in the diagnostic investigation, if additional visits to the clinician and additional sampling and diagnostic tests are taken into account, as well as inconvenience for the patient due to the delay in starting appropriate treatment.
In recent years, molecular methods have been developed to deal with exactly these problems.
Clinical Information
Onychomycosis, also called tinea unguium, is a fungal infection that affects either the fingernails or toenails. Fungal infections usually develop gradually over time, so any difference in the appearance or feel of the nails may be too subtle to notice at first.
Onychomycosis may involve any element of the nail unit, including the nail matrix, nail bed, or nail plate. Onychomycosis can cause pain, discomfort, and deformity and may produce serious physical and occupational limitations, as well as reduce the quality of life.
Symptoms of nail infection
- Thickened nail
- Whitish to yellow-brown discoloration
- Brittle, crumbly, or ragged nail
- Distorted shape
- A dark color, caused by debris building up under the nail
- Slightly unpleasant smell
Who’s at risk for fungal infections?
There are many different causes of fungal nail infections. Each cause has its own cure. Although many of the causes of a fungal nail infection are preventable, certain risk factors increase the likelihood of them occurring. Thus, onychomycosis is more likely to develop in the following cases:
- Patients with diabetes mellitus
- Conditions that cause poor blood circulation
- Age over 65 years
- Presence of artificial nails
- Swim in a public swimming pool
- Nail injury
- Skin injury around the nail
- Wet fingers or toes for an extended period of time
- Weakened immune system
- Closed-toe shoes, such as sneakers or boots
Nail infections occur more often in men than in women, and in adults than in children. These types of fungal infections are more likely to occur among members of the same family.
The elderly have a higher risk of developing onychomycosis because the blood circulation is poor and also because the nails grow more slowly and thicken over the years.
Etiology
Onychomycosis is caused by 3 main classes of fungi: dermatophytes, yeasts, and non-dermatophyte fungi. Dermatophytes are the most common cause of onychomycosis. Two main pathogens are responsible for approximately 90% of all cases of onychomycosis. Trichophyton rubrum accounts for 70% and Trichophyton mentagrophytes for 20% of all cases. Onychomycosis caused by non-dermatophyte fungi (Fusarium species, Scopulariopsis brevicaulis, Aspergillus species) is becoming increasingly common worldwide, accounting for up to 10% of cases. Onychomycosis due to various Candida species (yeasts) is relatively rare.
