A Comparative Study of Potassium Hydroxide Wet Mount, Calcofluor White Staining and Culture for the Diagnosis of Keratomycosis

Abstract

Background: The incidence of keratomycosis has increased dramatically in recent years. Early diagnosis and treatment of keratomycosis are important in preventing further complications. Direct microscopic techniques are time-saving for diagnosing keratomycosis when compared to culture methods. This study was carried out to determine the sensitivities of potassium hydroxide (KOH) wet mount, Gram stain and Calcofluor white (CFW) stain plus KOH wet mount by taking culture as the gold standard. Methods: Corneal scrapings were collected from 150 clinically suspected patients with keratomycosis. Demographic profile was collected and analyzed. Results: Of these patients, 67.33% were male, 24% were in the age group of 51-60 years, 70% were ruralresidents, 44% were agricultural workers, and 60% presented with a history of corneal trauma. Laboratory investigations have revealed that 29.33% (44 cases) were culture positive. In other words, Fusarium spp. was isolated in 17 cases, Aspergillus spp. in 14 cases, phaeoid fungi in 3 cases and unidentified fungi in 10 cases. The positivity of CFW stain plus KOH wet mount, KOH wet mount, and Gram stain was 30%, 23.3%, and 20%, respectively. Sensitivities of CFW stain plus KOH wet mount, KOH wet mount, and Gram stain were 79.55%, 54.55%, and 47.62%, respectively. Conclusion: Post-investigative analysis has revealed that CFW stain plus KOH wet mount was better than KOH wet mount alone in demonstrating fungal pathogens. Therefore, early diagnosis of keratomycosis by meticulous examination of corneal scrapings by direct microscopy specifically using CFW stain plus KOH wet mount and institution of antifungal therapy may limit ocular morbidity and disastrous sequelae among these patients.