A Two-Way Road: Antagonistic Interaction Between Dual-Species Biofilms Formed byCandida albicans/Candida parapsilosisandTrichophyton rubrum

Dermatomycoses include superficial fungal infections of the skin and its appendages.Trichophyton rubrum,Candida albicans, andCandida parapsilosisare some of the most prevalent species that cause dermatomycoses. Several studies show a variable predominance ofCandidaspp. in relation to dermatophytes, especially in onychomycosis and the possibility of isolating both from the same site. The ability of dermatophytes to form biofilms recently been explored and there is currently no evidence on the involvement of these filamentous fungi in multi-species biofilms. Thus, this study aims to investigate the probable dual-species interaction betweenT. rubrumandC. albicansandT. rubrumandC. parapsilosisbiofilms, considering variable formation conditions, as well as the susceptibility of these dual-species biofilms against terbinafine and efinaconazole. Three conditions of formation of dual-species biofilms were tested: (a) the suspensions ofT. rubrumandCandida albicansorC. parapsilosisplaced together; (b) suspensions ofC. albicansandC. parapsilosisadded the pre-adhesion ofT. rubrumbiofilms; (c) after the maturation ofT. rubrumsessile cells. In the first and second conditions, the quantification of metabolic activities, biomass, and polysaccharide materials of mixed biofilms tended to resembleCandidamonospecies biofilms. In the third condition, the profiles were modified after the addition ofCandida, suggesting thatT. rubrumbiofilms served as substrate for the development ofCandidabiofilms. Scanning electron microscopy showedCandidapredominance, however, numerous blastoconidia were noted, most evident in the conditions under whichCandidawas added after the pre-adhesion and maturation ofT. rubrumbiofilms. Despite the predominance ofCandida, the presence ofT. rubrumappears to inhibitC. albicansfilamentation andC. parapsilosisdevelopment, confirming an antagonistic interaction. Fungal burden assays performed when the biofilms were formed together confirmedCandidapredominance, as well as susceptibility to antifungals. Further studies will be needed to identify the components of theCandidaandT. rubrumbiofilm supernatants responsible for inhibiting dermatophyte growth andC. albicansfilamentation. (AU)