Most mycoses are difficult to treat because:

• A. Fungal infections are always caused by viruses, which are inherently difficult to treat.
• B. Fungal cells are eukaryotic and share many similarities with human cells, making selective toxicity challenging.
• C. Fungi reproduce exclusively by binary fission, which makes them resistant to antifungal drugs.
• D. Fungi lack cell walls, so most drugs cannot target them effectively.

Answer: (B)

Verified step by step guidance

1. Understand the nature of fungal cells: Fungi are eukaryotic organisms, meaning their cellular structure is similar to that of human cells, including membrane composition and organelles.
2. Recognize the concept of selective toxicity: Effective antimicrobial drugs target features unique to the pathogen without harming the host. Since fungi share many cellular features with humans, it is difficult to find targets that affect fungi but not human cells.
3. Evaluate the incorrect options: Viruses cause viral infections, not fungal infections; fungi do not reproduce exclusively by binary fission but often by spores; and fungi do have cell walls, which are actually a target for some antifungal drugs.
4. Conclude that the main reason mycoses are difficult to treat is due to the similarity between fungal and human cells, which limits the number of safe and effective antifungal agents.
5. Summarize that antifungal treatment challenges arise from the eukaryotic nature of fungi, making selective toxicity a key hurdle in developing antifungal therapies.