Biochemical and Physiological Profiles of Nakaseomyces glabratus Isolates from Bulgarian Clinical Samples

Nakaseomyces glabratus is an opportunistic fungal pathogen that primarily affects immunocompromised individuals. Unlike other Candida species, N. glabratus exhibits nondimorphic blastoconidial morphology and a haploid genome. It is a leading cause of both superficial (oral, esophageal, vaginal, or urinary) and systemic candidiasis. In this study, we evaluated 47 clinical isolates from Central Bulgaria (Plovdiv) and 1 wild strain isolated from the gut of the beetle Oxythyrea funesta (Coleoptera: Cetoniinae) collected in Sofia, Bulgaria. Growth was observed across a pH range of 3 to 9. The strains were assessed for the production of lipases, esterases, and proteases-enzymes associated with pathogenicity-and their relationship to virulence. Biofilm formation and exopolysaccharide production were also measured, with all strains showing similar profiles. No competitive inhibition of N. glabratus was observed against C. parapsilosis. All isolates exhibited resistance to micafungin, while resistance to both micafungin and anidulafungin was observed in 21 isolates (44%). These findings provide insight into the biochemical characteristics of N. glabratus populations from Southeast Europe, contributing to a better understanding of strain behavior under controlled laboratory conditions and addressing the gap in data on this species in the region.