A new cost-effective staining method for rapid identification of Cryptococcus

Cryptococcosis is a life-threatening fungal disease that usually presents as an opportunist infection in immunocompromised hosts, and Cryptococcus neoformans is the major opportunistic pathogen of cryptococcosis. Rapid diagnosis of C. neoformans and other opportunistic Cryptococcus pathogens is required to meet the clinical need for immediate treatment. Historically, negative staining with India ink has been used to identify Cryptococcus. Another staining method utilizes Alcian blue, a dye that reacts selectively with C. neoformans, but not other Cryptococcus species. To overcome these limitations, we developed a new staining method for rapid identification of Cryptococcus using a novel, patent pending staining reagent for clinical laboratory diagnosis. Cryptococci stained with this new reagent can be conveniently counted directly via bench-top light microscopy. We also compared our novel stain with India ink and Alcian blue. Our results demonstrated that the new staining technique was superior to India ink stain for the rapid identification of Cryptococcus in clinical (and clinically mimicking) samples. Our stable and cost-effective staining reagent specifically stained Cryptococcus, highlighting its clinical applicability, particularly in developing countries due to its low cost.