Which agent is commonly used to treat oral fungal infections in immunocompromised patients?

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

Answer: (B)

Treating oral fungal infections in immunocompromised patients relies on topical antifungals with high activity at the mucosal surface and minimal systemic exposure. Nystatin works by binding to ergosterol in the fungal cell membrane, creating pores that disrupt membrane integrity and lead to fungal cell death. Because it is not appreciably absorbed from the mouth, it delivers high local concentrations where the infection is while keeping systemic exposure very low—reducing the risk of drug interactions and systemic toxicity in patients already taking multiple medications. This safety profile, combined with effective activity against Candida species that commonly cause oral thrush, makes topical nystatin a preferred first-line option for oral candidiasis in immunocompromised individuals. Other agents like clotrimazole or miconazole are also useful, but systemic therapies such as fluconazole carry greater systemic exposure and potential interactions, which is why nystatin is often favored for localized oral infections in this population.