Fusarium spp. is able to grow and invade healthy human nails as a single source of nutrients

Abstract

Onychomycosis caused by Fusarium spp. is emerging, but some factors associated with its development remain unclear, such as whether this genus is keratinolytic. The main aim of the present study was to evaluate the ability of Fusarium to use the human nail as a single source of nutrients. We also performed an epidemiological study and antifungal susceptibility testing of Fusarium spp. that were isolated from patients with onychomycosis. The epidemiological study showed that Fusarium species accounted for 12.4 % of onychomycosis cases, and it was the most common among nondermatophyte molds. The most frequent species identified were F. oxysporum (36.5 %), F. solani (31.8 %), and F. subglutinans (8.3 %). Fluconazole was not active against Fusarium spp., and the response to terbinafine varied according to species. Fusarium was able to grow in vitro without the addition of nutrients and invade healthy nails. Thus, we found that Fusarium uses keratin as a single source of nutrients, and the model proposed herein may be useful for future studies on the pathogenesis of onychomycosis.

Antibiofilm Activity of Propolis Extract onFusariumSpecies from Onychomycosis

“…Onychomycosis caused by Fusarium spp. is frequent in Brazil and has been increasing in recent years [2,10]. Its pathogenesis and treatment, however, have not yet been completely elucidated.…”

“…It has recently been shown for the first time that Fusarium spp. can grow in vitro using human nails as a single source of nutrient; and also that members from this genus have the ability to invade healthy human nails [10]. In the current study, the capacity of clinical isolates of F. solani, F. oxysporum and F. subglutinans obtained from onychomycosis to form biofilms was demonstrated, a finding similar to those described by Costa-Orlandi et al (2014) [14] for the dermatophytes T. rubrum and T. mentagrophytes, which are the most common agents of onychomycosis.…”

“…Moreover, Fusarium spp. are highly resistant to azole antifungals which are not usually active against this fungus and terbinafine response varies according to species [10]. We have not therefore included a conventional antifungal as a control.…”

“…Nail scrapings were cultivated in three tubes containing Sabouraud dextrose agar (SDA; Himedia Laboratories, Mumbai, India) and three tubes that contained Mycosel medium (Himedia Laboratories, Mumbai, India). The identification of fungi was performed using classic methods, including the examination of colonies and microscopic morphology [10,11]. The fungi isolated and identified were maintained in a freeze-dried state in the Mycological Collection of the Laboratory of Medical Mycology of the State University of Maringá (UEM), Brazil.…”

Current antifungal treatment of fusariosis

“…The infections are clinically indistinguishable from onychomycosis by dermatophytes, and present as distal subungual, proximal subungual and total dystrophic infections [25,26]. Fusarium paronychia is often associated with onychomycosis and is characterised by periungual purulent inflammation, similar to that induced by Candida species [28,29]. The main species complexes responsible for onychomycosis are F. oxysporum and F. solani, with F. fujikuroi being less frequently involved [30].…”