Impact of Biofilm Formation by Vaginal Candida albicans and Candida glabrata Isolates and Their Antifungal Resistance: A Comprehensive Study in Ecuadorian Women

Candida albicans and Candida glabrata are key fungal pathogens linked to candidiasis, with rising concerns due to antifungal resistance and biofilm abilities. However, data from Latin America remains limited. This study assessed biofilm formation and antifungal susceptibility of vaginal Candida isolates from Ecuadorian women. Biofilm formation at 24 and 48 h was evaluated using biomass and CFU assays and the biofilm formation index. Antifungal resistance in planktonic cells and patient microbiota profiles were also analyzed. Biofilm assessment showed 57.14% of isolates were high biofilm formers, 33.33% intermediate, 4.76% low, and 4.76% non-formers. Planktonic susceptibility testing included fluconazole, voriconazole, posaconazole, caspofungin, anidulafungin, micafungin, flucytosine, and amphotericin B. Micafungin showed the lowest MBEC90 value among tested antifungals, with an average MIC of 0.15 µg/mL, MBIC90 of 1.26 µg/mL, and MBEC90 of 1.86 µg/mL. Fluconazole followed with MIC, MBIC90, and MBEC90 values of 4.19, 63.33, and 66.59 µg/mL. Flucytosine had the highest values (MIC = 11.36 µg/mL; MBIC90 = 244.71 µg/mL; MBEC90 = 245.33 µg/mL). Both micafungin and flucytosine produced similar reductions in viable biofilm cells (1.44 log CFU), while fluconazole induced a slightly lower reduction of 1.39 log CFU. Findings suggest echinocandins may be effective against biofilm-forming Candida in this Ecuadorian population subset.