Evaluation of biofilm formation and antimicrobial susceptibility (drug resistance) of Candida albicans isolates

Candida albicans comprises over 80% of isolates from all forms of human candidiasis. Biofilm formation enhances their capacity to withstand therapeutic treatments. In addition to providing protection, biofilm formation by C. albicans enhances its pathogenicity. Understanding the fundamental mechanisms underlying biofilm formation is crucial to advance our understanding and treatment of invasive Candida infections. An initial screening of 57 Candida spp. isolates using CHROMagar Candida (CHROMagar) media revealed that 46 were C. albicans. Of these, 12 isolates (33.3%) had the capacity to form biofilms. These 12 isolates were subjected to multiple biochemical and physiological tests, as well as 18 S rRNA sequencing, to confirm the presence of C. albicans. Upon analysis of their sensitivity to conventional antifungal agents, the isolates showed varying resistance to terbinafine (91.6%), voriconazole (50%), and fluconazole (42%). Among these, only CD50 showed resistance to all antifungal agents. Isolate CD50 also showed the presence of major biofilm-specific genes such as ALS3, EFG1, and BCR1, as confirmed by PCR. Exposure of CD50 to gentamicin-miconazole, a commonly prescribed drug combination to treat skin infections, resulted in elevated levels of gene expression, with ALS3 showing the highest fold increase. These observations highlight the necessity of understanding the proteins involved in biofilm formation and designing ligands with potential antifungal efficacy.