All patients with clinical suspicion of onychomycosis at the Tor Vergata Polyclinic center will be enrolled according to the inclusion and exclusion criteria of the study. After signing the informed consent, the subjects will be subjected to scraping or clipping of the nail unit affected by the disease. The collected material will be stored in a sterile container to be sent to the Microbiology laboratory.

Topical application of terbinafine

Change of Onychomycosis Severity Index (OSI) from baseline to 12 months:

• Area of Involvement (0-5 points)
• Proximity of Disease to Matrix (1-5 points)
• Presence of Dermatophytoma or Subungual Hyperkeratosis 2 mm ( 0 or 10 points)

Indicated by the number of patients with treatment-related adverse events assessed by Common Terminology Criteria for Adverse Events (CTCAE).

Complete Cure is defined as 1) 100% healthy, clear nail, and 2) negative mycology. Healthy, clear nail is absent any disease involvement attributable to DLSO and is determined by Investigator Global Assessment (IGA). Negative mycology is defined as zero visualization of septate hyphae by KOH microscopy (negative KOH) combined with a fungal culture negative for causal dermatophytes (negative fungal culture).

Evaluation of the quality of life of treated patients before and after treatment (0-30 points)

To establish each patient's impression of DLSO improvement in their target toe over the study period, patients will reference the following scale (0 = clear of DLSO, 1 = marked improvement of DLSO, 2 = moderately improved DLSO, 3 = slightly improved DLSO, 4 = unchanged, 5 = worse)

For each culture positive clinical sample, the status ("correct" or "incorrect") of the classification of the sample ("infected" or "not infected") by the test (MALDI-TOF MS profiling) will be determined. Then the rate of correct classification will be calculated. The test will be considered efficient when it has reached a correct classification rate of more than 95%.