Detection of Aspergillus keratitis in ocular infections by culture and molecular method.

The incidence of fungal keratitis has increased in recent years. Since accurate and rapid diagnosis is important for the proper management of this infection, we evaluated the use of nested PCR to detect Aspergillus-specific DNA in corneal scrapings for the diagnosis of Aspergillus keratitis. From April 2005 to September 2008, patients with eye findings suspicious for fungal keratitis were enrolled for corneal sampling. After ocular examination, we carried out laboratory testing including direct microscopy and culture examination of corneal scrapings, nested PCR and histopathological examination of the corneal tissues obtained at surgery. Of the 57 infected eyes suspicious for fungal keratitis, 32 (56.14%) were reported as Aspergillus keratitis by PCR assay, from which 12 (37.5%) were positive in culture and direct smear for Aspergillus keratitis, and 20 (62.5%) had clinical signs of fungal keratitis (probable). All PCR-positive cases were judged to have fungal infections, based on their responses to the antifungal treatment. The use of molecular methods in high-risk patients can be helpful in diagnosis of fungal infections and can have important public health implications for both the treatment and prevention of suppurative corneal ulcerations. The significance of this study lies in the analysis of the proven cases in terms of both laboratory findings and responses to the treatment.