Characterization of Candida spp. from the urinary tract: antifungal susceptibility and virulence traits

Introduction. Candida spp. are opportunistic pathogens frequently associated with nosocomial infections, and their incidence in urinary tract infections (UTIs) has increased significantly in recent decades, representing a serious public health concern.Hypothesis/Gap Statement. While fungal UTIs are gaining attention, there is a lack of comparative studies linking gender and specific niches to the pathogenic potential and antifungal resistance of Candida isolates in the genitourinary tract.Aim. The aim of this study is to characterize Candida spp. isolated from the urinary tract by investigating their incidence, antifungal resistance patterns and phenotypic virulence factors - including biofilm formation, germ tube production and adhesion to human epithelial cells - while specifically comparing these characteristics between male and female patients.Methodology. A total of 37 urinary isolates were collected from patients at a Portuguese public hospital between December 2022 and June 2023. Antifungal susceptibility to fluconazole (FLC) and clotrimazole (CLT) was determined via European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution. Virulence was assessed through crystal violet biofilm biomass quantification, germ tube formation assays for Candida albicans and adhesion assays using HeLa cells.Results. C. albicans was the most prevalent species, while Nakaseomyces glabratus was exclusively found in female patients (30%). All isolates were susceptible to FLC (MIC ≤2 µg ml^-1) and CLT (MIC ≤1 µg ml^-1). High biofilm biomass was particularly noted in non-albicans species and isolates from hospitalized patients. While isolates from male patients exhibited higher germ tube formation (P<0.05), those from female patients demonstrated a potentially greater capacity for adhesion to HeLa cells (P<0.05).Conclusion. Candida isolates from the urinary tract demonstrate a potential virulence trait that varies by patient gender and clinical setting. The findings suggest that hospitalized female patients and elderly patients harbour isolates with greater pathogenic potential, highlighting the need for continuous epidemiological surveillance to improve UTI diagnosis and treatment.