Clinical use of nystatin in infectious diseases Nystatin is primarily indicated for the treatment of diseases caused by which type of pathogen?

Introduction / Context:
Nystatin is a classic antifungal agent essential in dermatology and oral medicine. Knowing its spectrum helps clinicians choose the right therapy for candidiasis and other superficial mycoses while avoiding inappropriate antibacterial use.

Given Data / Assumptions:

• Nystatin belongs to the polyene class of antifungals.
• Polyene antifungals target fungal cell membranes.
• The question asks for the pathogen category primarily targeted.

Concept / Approach:
Nystatin binds to ergosterol in fungal cell membranes, creating pores that increase membrane permeability and cause leakage of intracellular contents. Because bacteria lack ergosterol (they have other sterol-free membranes) and protozoa do not rely on ergosterol like fungi, nystatin’s action is selectively antifungal.

Step-by-Step Solution:
Recall nystatin = polyene antifungal.Polyene mechanism: ergosterol binding and pore formation in fungi.Conclude that its main indication is Candida infections (oral thrush, cutaneous candidiasis).Select “Yeast and other fungi.”

Verification / Alternative check:
Standard formularies list nystatin for oral and cutaneous candidiasis; it is ineffective against bacteria and viruses.

Why Other Options Are Wrong:
Gram-negative/positive bacteria and protozoa lack ergosterol targets; antiviral activity is absent.

Common Pitfalls:
Assuming all “antimicrobials” work across domains. Antifungals and antibacterials have distinct targets.

Final Answer:
Yeast and other fungi (for example, Candida species).