Species Identification, Virulence Factors, and Antifungal Resistance in Clinical Candida Isolates from ICU Patients

Candida spp. are important opportunistic human fungal pathogens. This study aimed to identify and characterize Candida spp. obtained from patients admitted to an Intensive Care Unit (ICU), focusing on virulence attributes and susceptibility to antifungal agents. A total of 131 isolates from oral and tracheobronchial secretions of adult ICU patients were evaluated. Phenotypic identification was performed using chromogenic culture media for Candida, followed by MALDI-TOF mass spectrometry, with representative isolates confirmed by ITS sequencing. Antifungal susceptibility to fluconazole, ketoconazole, and amphotericin B was determined only by the agar disk diffusion method, and virulence was assessed through esterase, DNase, protease, and hemolytic activity assays. C. albicans was the prevalent species, followed by C. tropicalis, C. krusei, C. glabrata, C. parapsilosis, C. dubliniensis, C. lusitaniae, and C. guilliermondii. Antifungal resistance rates reached 51.1% for fluconazole, 42.7% for ketoconazole, and 19.1% for amphotericin B, as determined by disk diffusion method. Overall, 64.9% of the isolates exhibited esterase activity, 18.3% DNase, 45.8% protease, and 67.2% exhibited hemolytic activity. Oral isolates were more frequent than tracheal isolates and demonstrated a higher prevalence of antifungal resistance and virulence traits. These findings underscore the epidemiological importance of characterizing Candida species in hospitals to better understand the yeast profile and to support adequate clinical management.