Which medication is used as the drug of choice to treat fungal overgrowth in immunocompromised patients?

• A. Fluconazole
• B. Nystatin
• C. Clotrimazole
• D. Miconazole

Answer: (B)

Fungal overgrowth on mucosal surfaces, such as oral candidiasis in someone who is immunocompromised, is best treated with a topical antifungal that acts locally and has minimal systemic absorption. Nystatin fits this role well: it binds to ergosterol in fungal cell membranes, creating pores that disrupt the membrane and kill Candida, but it is not absorbed from the gastrointestinal tract. This local action provides effective mucosal treatment with very low risk of systemic toxicity or interactions—an important advantage in immunocompromised patients who may be sensitive to systemic therapies or drug interactions.

The other antifungals listed are azoles, which are typically systemic or have broader systemic effects and interaction profiles. While they can treat mucosal infections, the combination of local activity and safety makes nystatin the preferred initial choice for mucosal fungal overgrowth in these patients.