Colletotrichum fructicola-induced fungal keratitis: a case report and literature review

Fungal keratitis, a serious corneal infection that can lead to visual impairment and blindness, is commonly caused by Fusarium, Aspergillus, and Candida species; however, infections caused by Colletotrichum fructicola (C. fructicola) are rare. We report the first case of C. fructicola keratitis diagnosed in our hospital, and review the current literature on human infections caused by this fungus. A 66-year-old male agricultural worker presented with conjunctival hyperemia in the right eye after suffering a puncture from a chestnut thorn injury. Corneal scrape samples were collected. Morphological assessment of the colonies and internal transcribed spacer (ITS) sequencing confirmed fungal keratitis caused by C. fructicola. After ocular debridement, the patient underwent surgical intervention to remove the foreign body from the right eye. Postoperatively, the topical antifungal voriconazole was administered. The patient subsequently showed improvement in his clinical condition. During treatment, an improvement in corneal clarity was observed, culminating in a significant enhancement of visual acuity from 0.3 to 0.6 by 3 months postoperatively. Although traditional morphological methods have inherent limitations in reliably identifying C. fructicola, their combination with ITS sequencing enables rapid and accurate species-level diagnosis. Treatment for Colletotrichum keratitis involves aggressive topical antifungal treatment, escalation to systemic antifungal therapy, and surgery in severe cases.