Comparison of KOH, Calcofluor White and Culture for the diagnosis of Keratomycosis from a Tertiary Care Hospital

Background: Mycotic keratitis is an important ophthalmic problem. Scarring of cornea as a result of keratitis is one of the preventable causes of blindness and carries usually unfavourable prognosis and requires immediate specific therapy. Worldwide, the reported incidence of mycotic keratitis is 17% to 36%. Microbial culture and direct microscopic detection using 10 KOH% and Calcofluor white stain always supplements the clinical diagnosis. This study involves comparison of KOH, Calcofluor white and Culture for the diagnosis fungal corneal ulcer. Material and Methods: This cross-sectional study was conducted in the Department of Microbiology and Ophthalmology, MMIMSR from Oct 2013 to Oct 2014 on 60 corneal scraping samples from clinically suggested cases of infectious keratitis. Corneal scrapings were collected aseptically and subjected to direct microscopy by 10 KOH% and Calcofluor white stain for detection of fungal elements and fungal culture. Result: Out of 60 suspected cases of corneal ulcer, culture positivity was 43.3% which included 8 (30.76%) bacterial, 16 (61.53%) fungal and 2 (7.69%) mixed isolates respectively. Out of the 24 fungal pathogens, 100% were detected by microscopy and 75% by culture. 100% and 87.5% fungus was detected by Calcofluor white and KOH respectively. Aspergillus species was the most prevalent pathogen followed by Fusarium solani and Curvularia geniculata. Conclusion: Calcofluor white stain was found to be an excellent method in detection of fungal agents. KOH wet mount was also found to be a good alternate method in resource-poor settings. Mycological culture was the least efficient method however it may be used in routine for the identification of species.