Which of the following antifungals acts primarily by disrupting fungal cell membrane integrity?

The correct answer is Nystatin, which primarily acts by disrupting fungal cell membrane integrity. Nystatin belongs to the polyene class of antifungals and works by binding to ergosterol, a critical component of the fungal cell membrane. When Nystatin binds to ergosterol, it forms pores in the membrane, leading to increased permeability and ultimately causing cell lysis and death of the fungus. This mechanism makes Nystatin particularly effective against Candida species and some other fungi.

In contrast, Ketoconazole and Fluconazole are azole antifungals that inhibit fungal cell growth by interfering with ergosterol synthesis rather than directly disrupting the cell membrane. Ketoconazole inhibits the enzyme lanosterol demethylase, leading to a decrease in ergosterol production, which destabilizes the membrane but does not cause direct lysis. Fluconazole similarly inhibits the same enzyme but is generally used for different types of fungal infections and has better oral bioavailability.

Caspofungin is an echinocandin that works by inhibiting the synthesis of β-(1,3)-D-glucan, an essential component of the fungal cell wall, rather than the cell membrane. This action leads to weakened cell wall integrity but does