Background: Malassezia species rarely cause keratitis, and, thus, the clinical manifestations of Malassezia keratitis are not well known.
Case: We report the clinical findings in a 70-year-old woman who complained of pain in her left eye. Slit-lamp biomicroscopy showed a corneal ulcer with irregular infiltration, which resembled keratitis caused by filamentous fungi. KOH Parker ink stain of a corneal scraping showed mold hyphae and yeast, but cultures on Sabouraud's glucose agar plates and blood agar plates were negative. Treatment with antibacterial agents failed.
Observations: Polymerase chain reaction (PCR) and DNA typing of the fungal gene between the internal transcribed spacer 2 (ITS2) and the 5.8S ribosomal DNA of the scraping were performed. PCR amplified a band with a sequence that was 99% homologous with Malassezia restricta. Antifungal agents, topical 5% pimaricin ointment and 0.2% miconazole, and oral itraconazole 150 mg/day, were applied, and the corneal ulcer disappeared within 5 weeks.
Conclusion: Malassezia restricta can cause keratitis, and the clinical findings resemble keratitis caused by filamentous fungi. PCR and DNA typing of ITS2 and 5.8S ribosomal DNA are valuable techniques for detecting and identifying Malassezia species. Proper identification of Malassezia keratitis permits a prompt and successful treatment by antifungal agents.