Which antifungal agent acts by inhibiting the synthesis of β-1,3-glucan, a key structural component of the fungal cell wall?

Explanation

## Mechanism of Echinocandins **Key Point:** Echinocandins (caspofungin, micafungin, anidulafungin) inhibit fungal cell wall synthesis by blocking β-1,3-glucan synthase, the enzyme responsible for glucan polymer formation. ### Cell Wall Target The fungal cell wall is composed primarily of: - β-1,3-glucan (structural backbone) - Chitin - Mannoproteins Inhibition of β-1,3-glucan synthesis leads to: 1. Weakening of cell wall integrity 2. Cell lysis and fungal death 3. Fungicidal activity (not fungistatic) **High-Yield:** Echinocandins are the **first-line agents for invasive candidiasis** and are particularly effective against *Candida* species and *Aspergillus*. They have poor oral bioavailability and must be given intravenously. ### Comparison with Other Antifungals | Agent | Target | Mechanism | Activity | |-------|--------|-----------|----------| | **Echinocandin** | β-1,3-glucan synthase | Cell wall synthesis inhibition | Fungicidal | | **Amphotericin B** | Ergosterol | Cell membrane disruption | Fungicidal | | **Fluconazole** | Lanosterol 14α-demethylase | Ergosterol synthesis inhibition | Fungistatic | | **Terbinafine** | Squalene epoxidase | Ergosterol synthesis inhibition | Fungicidal | **Clinical Pearl:** Echinocandins show minimal drug interactions and are safe in renal impairment, making them ideal for critically ill patients with multiorgan dysfunction.