Comparative Study of Gram Stain, Potassium Hydroxide Smear, Culture and Nested PCR in the Diagnosis of Fungal Keratitis

Abstract

OBJECTIVE: This study seeks to evaluate the efficacy and practicality of the molecular method, compared to the standard microbiological techniques for diagnosing fungal keratitis (FK). METHODS: Patients with eye findings suspected of FK were enrolled for cornea sampling. Scrapings from the affected areas of the infected corneas were obtained and were divided into two parts: one for smears and cultures, and the other for nested PCR analysis. RESULTS: Of the 38 eyes, 28 were judged to have fungal infections based on clinical and positive findings in the culture, smear and responses to antifungal treatment. Potassium hydroxide, Gram staining, culture and nested PCR results (either positive or negative) matched in 76.3, 42.1, 68.4 and 81.6%, respectively. CONCLUSION: PCR is a sensitive method but due to the lack of sophisticated facilities in routine laboratory procedures, it can serve only complementarily and cannot replace conventional methods.