The repertoire of yeast species from human clinical samples in the United Kingdom 2016-2022: epidemiology, clinical relevance, and fluconazole resistance.

The United Kingdom National Mycology Reference Laboratory (MRL) performs routine identification and susceptibility testing of isolates of pathogenic yeasts from diverse clinical samples submitted from across the UK. Here, we extracted data from our laboratory information management system for all yeasts referred to the laboratory for the period 2016-2022. Data for a total of 17,631 isolates comprising 95 species were retrieved and analyzed according to frequency of recovery from each clinical sample type and anatomical site. In agreement with most international epidemiological surveys, Candida albicans and Nakaseomyces glabratus (syn. Candida glabrata) were the two most common yeast species identified, comprising cumulatively over 66% of all isolates referred to the MRL. C. albicans and N. glabratus predominated in frequency from all anatomical sites except the central nervous system, where Cryptococcus neoformans was the most frequently encountered, and respiratory secretions from cystic fibrosis patients and ocular samples, where Candida parapsilosis prevailed. The diversity of different species recovered from sputum, and the oral cavity was predictably large, in keeping with the contamination of the oropharynx by myriad yeasts introduced with food and beverages, in addition to those organisms that naturally occur as commensals on upper respiratory surfaces. More surprising was the diversity of organisms recovered from blood cultures, with 60 different species encountered during the study period. Finally, analysis of fluconazole susceptibility data for C. albicans, C. parapsilosis, and C. tropicalis demonstrated that fluconazole resistance in these organisms is currently reassuringly rare in the UK except in isolates causing superficial mucosal infections.IMPORTANCEHere, we analysed over 17,000 isolates of yeast by anatomical/clinical site, highlighting an enormous range of species (>60) that can cause fungemia. Our data highlight that resistance to fluconazole in key pathogenic Candida species (C. albicans, C. tropicalis, C. parapsilosis) is currently rare in isolates from deep sites in the United Kingdom.