Fungal Biofilm in Onychomycosis

Abstract

Onychomycosis refers to fungal infection that involves components of nail unit including: nail matrix, nail bed and/or nail plate. Although onychomycosis is not considered to be a life threatening condition, it does not self-heal and may be a source of widespread cutaneous fungal infections. Without treatment, fingernails become disfigured and look ugly. Negative emotional and psychosocial effects are common and may have respectable impacts on quality of person’s life. Several predisposing factors for onychomycosis have been identified including prolonged exposure to humid environments as wearing high tight shoes, secondary to other cutaneous fungal infections, vascular insufficiency, diabetes mellitus as well as impaired immunity. Diagnosis of onychomycosis depends on both clinical examination and mycological investigations such as: direct light microscopic examination with KOH mounted nail specimens or cultures on specialized agar.

Fungal organisms implicated in onychomycosis are yeasts, non-dermatophytes moulds and dermatophyte species. In onychomycosis, the firm fungal surface adherence, presence of dormant fungal elements and difficulty of eradicating the pathogenic organism despite long courses of systemic antifungal agents suggest that biofilms may be related to the chronicity of onychomycosis. Fungal biofilms in nail infections may act as a persistent infective focus and account for antifungal resistance in recalcitrant onychomycosis. The concept of biofilm associated dermatophyte infections in recalcitrant onychomycosis caused by dermatophytes was firstly introduced by Burkhart et al. (2002). Biofilms are defined as ‘’a structured community of microbial cells adherent to a surface and enclosed in a self produced extracellular polymeric matrix’’ A total of 54 patients with onychomycosis were enrolled in the study, of which the mean age was 56 years and mean duration of the disease was 28 months. Total number of affected nails was 377. Fingernail onychomycosis accounted for 21/54 cases with 79/377 nails while, toenail