Because amphotericin B is toxic to humans, most clinicians prescribe it only for
a. dermatophyte infections
b. Malassezia infections
c. systemic infections
d. mushroom poisoning

Verified step by step guidance

1. Step 1: Understand the nature of amphotericin B. Amphotericin B is an antifungal medication known for its broad-spectrum activity against many fungi but also for its significant toxicity to human cells, especially kidney cells.
2. Step 2: Recognize the types of infections listed in the options. Dermatophyte infections are superficial fungal infections affecting skin, hair, and nails. Malassezia infections are typically superficial yeast infections affecting the skin. Mushroom poisoning is caused by ingestion of toxic mushrooms and is not treated with antifungals.
3. Step 3: Consider the clinical use of amphotericin B. Due to its toxicity, amphotericin B is generally reserved for severe or life-threatening fungal infections, particularly those that are systemic (affecting internal organs or the bloodstream).
4. Step 4: Analyze each option in the context of amphotericin B's toxicity and typical clinical use. It is not commonly used for superficial infections like dermatophytes or Malassezia because safer antifungals are available. It is not used for mushroom poisoning, which requires different treatment.
5. Step 5: Conclude that amphotericin B is primarily prescribed for systemic fungal infections, where the benefits outweigh the risks of toxicity.

Key Concepts

Amphotericin B and Its Mechanism of Action

Amphotericin B is an antifungal drug that binds to ergosterol in fungal cell membranes, creating pores that cause cell death. It is effective against a broad range of fungi but can also bind to cholesterol in human cells, leading to toxicity.

Toxicity and Clinical Use of Amphotericin B

Due to its significant side effects, including kidney damage, amphotericin B is reserved for severe or systemic fungal infections rather than superficial or mild infections. Clinicians use it cautiously when the benefits outweigh the risks.

Systemic Fungal Infections

Systemic fungal infections affect internal organs and can be life-threatening, requiring potent antifungal treatment. Amphotericin B is often prescribed for these serious infections because of its broad antifungal activity despite its toxicity.