Antifungal Susceptibility Profile and Biocide Tolerance in Clinically Relevant Yeasts: Implications for Therapy and Hospital Infection Control

ABSTRACT Background Opportunistic yeasts account for a substantial proportion of invasive fungal infections and are important agents of healthcare‐associated infections, especially in intensive care units (ICUs). Objectives To describe the clinical and epidemiological characteristics of hospitalized patients with positive cultures for medically relevant yeasts and correlate these data with antifungal susceptibility, biocide tolerance and phenotypic efflux pump activity. Methods Ninety‐four clinical isolates were analysed: 31 Trichosporon asahii , 39 Candida albicans and 24 other yeasts. Antifungal susceptibility and biocide tolerance were assessed by disk diffusion, and phenotypic efflux pump activity was evaluated using ethidium bromide. Clinical and epidemiological data were retrieved from electronic health records. Results Most isolates (73.4%) originated from ICUs. Urine (55.3%) was the most frequent clinical specimen. Overall mortality was 62.7%, reaching 71.8% among patients with C. albicans . Notably, 68.1% of patients did not receive antifungal therapy after diagnosis. All T. asahii isolates were susceptible to azoles and resistant to caspofungin. C. albicans showed high susceptibility to amphotericin B (100%) and caspofungin (93%). Phenotypic efflux pump activity was observed in all evaluated yeasts. Sodium hypochlorite showed greater antifungal activity, with inhibition zones of up to 18.0 mm, while hydrogen peroxide (4.25%) and benzalkonium chloride (5%) showed minimal zones (~6 mm) for all isolates. Conclusions Opportunistic yeast infections continue to pose a major challenge in healthcare settings. Our findings highlight the critical importance of accurate laboratory identification, ongoing surveillance of antifungal susceptibility, and effective infection prevention and control strategies, including the rational selection of biocides, to improve patient outcomes.