Successful management of pediatric Pythium insidiosum keratitis - A case report highlighting the role of targeted antimicrobial therapy and mechanical debridement.

Human pythiosis keratitis is a rare but potentially sight-threatening infection. We report the case of an 8-year-old boy who developed a nonhealing corneal ulcer after finger nail trauma that did not respond to broad-spectrum antibiotics. Initial cultures identified Staphylococcus warneri and Streptococcus mitis. Worsening clinical signs prompted repeat investigations, which confirmed Pythium insidiosum through polymerase chain reaction. Despite intensive topical (natamycin and voriconazole) and systemic antifungals (voriconazole), the ulcer progressed with biofilm formation. Manual debridement and a revised regimen of topical linezolid 0.2% alternating with topical ceftazidime 5% led to significant clinical improvement. After 8 weeks of topical therapy and regular debridement, the infection eventually resolved with a paracentral scar and unaided visual acuity of 6/6. This case highlights the diagnostic complexity of Pythium keratitis and the crucial role of early microbial identification in pediatric ocular trauma. We attribute the successful management in this case to prompt diagnostic reevaluation, targeted antimicrobial therapy, and repeated scraping of ulcer biofilm.