Epidemiology of echinocandin resistance in .

Echinocandins are the newest antifungal agents approved for use in treating infections in the US. They act by interfering with 1,3-β-D-glucan synthase and therefore disrupt cell wall production and lead to cell death. There is no intrinsic resistance to echinocandins among species, and isolates from historic collections archived before the release of the echinocandins show no resistance. Resistance to the echinocandins remains low among most species and ranges overall from 0-1%. Among isolates of , the proportion of resistant isolates is higher and has been reported to be as high as 13.5% in at least one hospital. Antifungal resistance is due to specific amino acid mutations in the Fksp subunit(s) of the 1,3-β-D-glucan synthase protein which are localized to one of two hotspots. These mutations are being recognized in isolates from patients who have failed echinocandin therapy, and often lead to a poor outcome. While the future looks bright for the echinocandins against most species, remains a species of concern and resistance rates of to the echinocandins should be monitored closely.