Which antifungal agent binds ergosterol and weakens the fungal cell wall?

Which antifungal agent binds ergosterol and weakens the fungal cell wall?

• A. Fluconazole
• B. Amphotericin B
• C. Micafungin
• D. Nystatin

Answer: (D)

Polyenes target the fungal cell membrane by binding to ergosterol, then create pores that disrupt membrane integrity and cause leakage of ions and other essential molecules, leading to cell death. This membrane-acting mechanism is what makes them effective antifungals, and it’s distinct from how other antifungals work (azoles block ergosterol synthesis, echinocandins weaken the cell wall). Among the options, the agent that binds ergosterol is the one that directly interacts with the membrane in this way, making it the best choice. It’s typically used topically because systemic administration can be toxic. The description that it weakens the fungal cell wall isn’t accurate for this mechanism; weakening the cell wall is the action of echinocandins, which inhibit beta-1,3-D-glucan synthesis.

Polyenes target the fungal cell membrane by binding to ergosterol, then create pores that disrupt membrane integrity and cause leakage of ions and other essential molecules, leading to cell death. This membrane-acting mechanism is what makes them effective antifungals, and it’s distinct from how other antifungals work (azoles block ergosterol synthesis, echinocandins weaken the cell wall).

Among the options, the agent that binds ergosterol is the one that directly interacts with the membrane in this way, making it the best choice. It’s typically used topically because systemic administration can be toxic. The description that it weakens the fungal cell wall isn’t accurate for this mechanism; weakening the cell wall is the action of echinocandins, which inhibit beta-1,3-D-glucan synthesis.