Echinocandins (caspofungin, micafungin, anidulafungin) are fungicidal against Candida species but only fungistatic against Aspergillus. This difference is because:

• A Aspergillus lacks the FKS1 gene encoding β-1,3-glucan synthase
• B Aspergillus hyphae have lateral cell wall reinforcement even when β-1,3-glucan synthesis is inhibited, allowing structural integrity to be maintained ✓
• C Echinocandins cannot penetrate the thick Aspergillus cell wall to reach β-1,3-glucan synthase
• D Aspergillus predominantly uses chitin (not β-1,3-glucan) as its cell wall scaffold

Explanation

Echinocandins inhibit β-1,3-glucan synthase, disrupting cell wall synthesis. In Candida, this removes the main structural polysaccharide, causing osmotic lysis (fungicidal). In Aspergillus, active hyphal growth occurs at hyphal tips; echinocandins damage the tips but lateral hyphae maintain integrity, limiting the drug to fungistatic effects rather than complete killing. Aspergillus does express FKS1; echinocandins do penetrate it; and chitin is a component of both fungi but not the primary target.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.