Epidemiology of antifungal resistance in human pathogenic yeasts: current viewpoint and practical recommendations for management

- Rates of antifungal resistance and multidrug resistance (MDR) in Candida spp., especially C. glabrata, are increasing.
- In C. glabrata, DNA mismatch-repair mutations confer a 'mutator' phenotype.
- Rare non-albicans Candida spp. can be resistant to echinocandins and polyenes.
- Candida auris exhibits MDR and potential for nosocomial transmission.
- Echinocandin resistance is common among non-Candida, non-Cryptococcus yeasts.

In this review, we describe the epidemiology and clinical significance of resistance in Candida spp. and other non-Cryptococcus yeasts. The rise in echinocandin resistance, azole resistance and cross-resistance to two or more antifungal classes [multidrug resistance (MDR)] has been a worrisome trend, mainly in US large tertiary and oncology centres, particularly as it relates to Candida glabrata. Candida kefyr is also a concern as it can be resistant to echinocandins and polyenes, especially in patients with haematological malignancies. Lately, Candida auris has drawn a lot of attention: this uncommon Candida spp. is the first globally emerging fungal pathogen that exhibits MDR and strong potential for nosocomial transmission. Its almost simultaneous spread in four continents could be indicative of increasing selection pressures from the use of antifungal agents. Echinocandin non-susceptibility is also common among non-Candida, non-Cryptococcus yeasts. As Candida resistance patterns reflect, in part, institutional practices of antifungal administration, the benefits of antifungal stewardship protocols are increasingly recognised and endorsed in recent guidelines. Development of rapid diagnostic methods for detecting or ruling out the presence of candidaemia and antifungal resistance, as well as discovery of novel antifungals, are key priorities in medical mycology research.