Abstract
Abstract: :
Purpose: To assess the sensitivity and specificity of calcofluor white in detecting acanthamoeba cysts in cases of acanthamoeba keratitis. Methods: Corneal specimens from five cases each of acanthamoeba keratitis, herpes keratitis and fungal keratitis that had been routinely processed and embedded in paraffin were serialy sectioned and stained with hematoxylin-eosin (H&E), giemsa, gram, gomori methanamine silver (GMS), periodic acid Schiff (PAS), acridine orange and calcofluor white. The sections were examined in a masked fashion by one observer who made a diagnosis of acanthamoeba, herpes or fungal keratitis. All slides were examined by an Olympus BHTU® bright field microscope or a fluorescent microscope. Results: The results showed the most consistent stains for the diagnosis of acanthamoeba, fungus and herpes were H&E followed by PAS, GMS, acridine orange, calcofluor white, gram and giemsa. The only false positives were with calcofluor white and acridine orange. The calcofluor white stain often stained cellular and extracellular debris. Conclusions: A routine hematoxylin and eosin stain is superior to calcofluor white and acridine orange stains to detect acanthamoeba cysts. Due to the time and cost involved with evaulating fluorescence staining of calcofluor white and acridine orange to diagnose acanthamoeba, we do not recommend the use of calcofluor white or acridine orange.
Keywords: Acanthamoeba • pathology: human • keratitis