Purpose: To describe the first case of Pythium insidiosum keratitis masquerading as dematiaceous fungal keratitis in a seropositive male.
Case summary: A 44-year-old seropositive male previously treated for acute retinal necrosis presented with pain and defective vision in the right eye following a mud injury 5 days back. Presenting visual acuity was hand movements close to the face. Ocular examination revealed a 7 × 7 mm dense, greyish-white mid stromal infiltrate with pigmentation and few tentacles. The clinical diagnosis suggested fungal keratitis. Corneal scraping on 10% KOH and Gram stain revealed slender, aseptate hyaline hyphae. Before culture results, the patient was treated with topical 5% natamycin and 1% voriconazole, but the infiltrate progressed. Culture on 5% sheep blood agar revealed white fluffy, submerged, shiny, and appressed colonies, and Pythium insidiosum was confirmed by zoospore formation. The patient was further managed with topical linezolid 0.2% hourly, azithromycin 1% hourly, and adjuvant drugs.
Conclusion: This is an uncommon presentation of Pythium keratitis masquerading as dematiaceous fungal keratitis in an immunocompromised male.
Keywords: Asian; fungal keratitis; immunocompromised; pythium insidiosum; seropositive.