A cerebrospinal fluid sample from an HIV-positive patient is examined using India ink preparation. A clear halo is observed around the yeast cells against a dark background. What is the target structure visualized by this negative staining technique?
- A Cell wall
- B Capsule ✓
- C Nucleus
- D Endospore
Correct answer: B. Capsule
Explanation
India ink negative staining is used to visualize the polysaccharide capsule of Cryptococcus neoformans. The ink particles cannot penetrate the capsule, creating a clear halo around the yeast cell against the dark background. The cell wall, nucleus, and endospore are not specifically highlighted by this method.
Reference: Jawetz, Melnick, & Adelberg's Medical Microbiology, 28th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.