Clinical Characteristics and Causative Agents of Toenail Onychomycosis among Small Traders in Nghe An Province, Vietnam

Abstract Objective To investigate the clinical presentation and causative agents of toenail onychomycosis in Vietnam. Methods A cross-sectional study was conducted across Nghe An province from March 2021 to August 2022. Toenail samples were collected from small-traders with suspected onychomycosis and underwent direct examination and culture. The isolated strains were identified by conventional and molecular techniques, including restriction fragment length polymorphism (RFLP) analysis and sequencing of the internal transcribed spacer (ITS) region. Results A total of 104 participants, aged 25 to 77 years (98.1% female), were diagnosed with toenail onychomycosis. Most lesions appeared on the first (92.4% of affected nails) and second toenails. The most common form was distal and lateral subungual onychomycosis (84.6%), followed by superficial white onychomycosis (8.7%) and proximal subungual onychomycosis (6.7%). The rates mild, moderate or severe onychomycosis were 35.6%, 39.4%, and 25.0% respectively. Yeasts accounted for the majority of infections (70.2%), with Candida being the most prevalent genus (54.8%), followed by Trichosporon (13.5%) and Geotrichum (1.9%). Aspergillus was the most prevalent mold identified (17.3%), followed by Penicillium (6.7%), Curvularia (2.9%), and Fusarium, Talaromyces, and Trichophyton (1% each). Yeast infections exhibited a significantly higher proportion of mild to moderate cases compared to mold infections (82.2% vs. 58.1%, p = 0.013). Conclusion Yeasts and non-dermatophyte molds are the leading causes of onychomycosis among traders in Nghe An province. Broad-spectrum antifungal agents appear to be a rational choice for the treatment.