Figure 2.

Mechanisms of resistance to antifungal drugs that target the cell wall—the echinocandins. (A) Mutations in FKS1, which encodes the catalytic subunit of the echinocandin target (1,3)-β-d-glucan synthase, are the most prevalent cause of echinocandin resistance. Cellular stress-response pathways modulate resistance phenotypes. Bullet points describe resistance mechanisms for C. albicans and A. fumigatus. Dimmed images represent mechanisms that do not play a key role in resistance. (B) Distribution of acquired mutations and naturally occurring polymorphisms within FKS genes conferring reduced echinocandin susceptibility. (From Cowen 2008; adapted, with permission, from Macmillan © 2008, and from Perlin 2007; adapted, with permission, from Elsevier © 2007.)