The antifungal drug classes include: polyenes, azoles, allylamines, flucytosine, and echinocandins (Groll et al. 1998; Kathiravan et al. 2012). The azoles (e.g., fluconazole, voriconazole, and posaconazole) and allylamines (e.g., terbinafine) inhibit ergosterol biosynthesis, whereas polyenes (e.g., amphotericin B) bind to ergosterol in the plasma membrane, where they form large pores that disrupt cell function. Flucytosine (5-fluorocytosine) inhibits pyrimidine metabolism and DNA synthesis. Finally, the echinocandins (caspofungin, anidulafungin, and micafungin) are cell wall–active agents that inhibit the biosynthesis of β-1,3-d-glucan, a major structural component of the fungal cell wall. The widespread use of antifungal agents is presumed to be a factor that promotes drug resistance