A corneal scraping from a suspected Acanthamoeba keratitis case is sent for laboratory evaluation. Which staining method provides the highest sensitivity for demonstrating Acanthamoeba cysts on direct microscopy?
- A Gram stain
- B Giemsa stain
- C Calcofluor white ✓
- D Lactophenol cotton blue
Correct answer: C. Calcofluor white
Explanation
Calcofluor white binds to chitin and cellulose in the cyst wall and shows high sensitivity under fluorescence microscopy. Gram stain and Giemsa have lower sensitivity. Lactophenol cotton blue is used for fungal hyphae visualization, not Acanthamoeba cysts. Culture on non-nutrient agar with E. coli overlay remains the gold standard.
Reference: AAO BCSC Section 8: External Disease and Cornea, 2022-2023 ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.