P289 A teenage with Pythium keratitis—a case report

POSTER SESSION 2, SEPTEMBER 22, 2022, 12:30 PM - 1:30 PM: INTRODUCTION: Pythium is an oomycete found in an aquatic environment and is considered to be a plant pathogen. However, it is able to cause ocular and systemic infections in humans and animals. Keratitis or corneal ulceration caused by Pythium species closely resembles fungal keratitis and is known as a pseudo-fungal infection. It is associated with high ocular morbidity owing to the difficulty in diagnosis and treatment. CASE REPORT: A 13-year-old adolescent from rural Sri Lanka presented with pain and tearing from left eye for 3 weeks’ duration. He was previously healthy and had no history of trauma to the eye. He had bathed in a lake recently. On examination, visual acuity was only perception of light and there was a corneal ulcer in the left eye. Since the ulcer had a poor response to medical therapy, penetrating keratoplasty was performed twice with failure of the graft. Direct smear of both corneal buttons revealed broad aseptate filaments with occasional branches at right angles that mimic fungi of zygomycetes. Culture on Sabouraud Dextrose Agar yielded expanding white submerged colonies. In the tease mount, hyaline, occasionally septate broad fungal filaments were visible. Therefore, the organism was identified as Pythium species in the Mycology Reference Laboratory. Repeated intracameral and intrastromal antifungal and topical and systemic antibiotic treatment resulted in a quiet, vascularized eye with the retained perception of light. DISCUSSION: Pythium keratitis carries a significant challenge in laboratory diagnosis due to its mycelial-like appearance. Nested PCR has higher accuracy than standard culture identification. Not being a true fungus, Pythium lacks ergosterol. Therefore, it is usually resistant to many commonly used antifungal agents which target ergosterol. High degree of suspicion is important for accurate identification in the laboratory and the clinicians should be informed for early, aggressive surgical intervention along with antimicrobial therapy in order to achieve a satisfactory outcome.