Clinico-Mycological Study of Fungal Biofilms in Recalcitrant Onychomycosis

Abstract

Objective: Studying the incidence of different predisposing factors of onychomycosis and the ability of fungal isolates to form biofilms. Background: Onychomycosis chronicity is referred to difficulties in eliminating the causative pathogens. Biofilms have become focus of era and considered to be one of the globally important causes of chronic recalcitrant infections. Fungi implicated in onychomycosis have the ability to form biofilms ''surface-attached multi-cellular communities''. Biofilm associated fungi acquire higher adaptive ability to overcome stressful conditions, higher antifungal resistance and evasion of host defensive systems. Moreover, they express community-based differential genes and more virulence activities. Methods: Fifty-four military male patients with onychomycosis were enrolled in this study from March, 2015 to October, 2015. All patients participating signed an informed detailed consent, full history taking, general and local examination and clinical photography. Nail specimen were collected to be examined by using direct light microscopy of 20%KOH nail mounts, cultured on different fungal agars media and to evaluate the ability of isolates to form biofilms as well as quantity by using (RPMI)-1640 buffered with (MOPS) (HiMedia, India) and (XTT) solution (Sigmaaldrich, USA), respectively. Results: While fungal elements were observed only in 51% of 20%KOH nail mounts by direct light microscopy, all specimen gave positive culture results (26 C. albicans, 26 T. rubrum and 2 M. canis). Twenty-eight isolates (19 C. albicans and 9 T. rubrum) were able to form biofilms in vitro. Biofilm forming ability was significantly related to positive history of nail exposure to high humidity micro environments (p=0.05), repeated or rough nail trauma (p=0.006), diabetes mellitus (p=0.003) and past history of receiving antifungal agents before the present study (≥ 5 months according to the exclusion criteria) (p=0.006). Conclusions: We found significant relations between the ability of fungi to form biofilm and factors that paly role in recalcitrant onychomycosis infections such as repeated minor nail trauma, high micro environmental humidity, complications of diabetes mellitus and antifungal misuse (type, dose and/or duration).