Colletotrichum keratitis: A rare yet important fungal infection of human eyes

Abstract

Summary Background Colletotrichum is a rare cause of human infection. Previous reports about Colletotrichum keratitis were limited, and most diagnoses from past reports were based on morphological distinction, which could have led to underestimation of the prevalence of Colletotrichum species. Objective We reported phylogenetic analysis, clinical feature and treatment outcome of molecularly diagnosed Colletotrichum keratitis in our hospital. Patients/Methods We recruited 65 patients with culture‐proven filamentous fungal keratitis between January 1, 2015 and December 30, 2018. Through molecular sequencing including internal transcribed spacer (ITS) and multi‐locus phylogenetic analysis of fungal DNA, seven patients were verified as infected with Colletotrichum species, and their medical records were reviewed to determine the clinical characteristics. Results Six of seven patients had predisposing factors including trauma (5) and immunosuppressive status (1). Six isolates were initially misidentified as other fungi through morphological identification. ITS sequencing identified the isolates belonged to two species complex (SC): C. truncatum and C. gloeosporioides; multi‐locus phylogenetic analysis enabled species identification including C. tropicale (3), C. fructicola (2), C. truncatum (1) and C. fusiforme (1). Five patients with C. gloeosporioides SC responded well to medical treatment and two patients with C truncatum SC underwent evisceration because of either no visual potential or intractable pain. Conclusions The molecular approach provides accurate diagnosis and raises epidemiological awareness of Colletotrichum keratitis. Through multi‐locus phylogenetic analysis, we report the human infections caused by C. tropicale, C. fructicola and C. fusiforme. We also highlight the different clinical outcomes between C. gloeosporioides SC and C. truncatum SC.

Colletotrichum asianum: A Novel Phytopathogen Causing Human Infection—A Case Report

“…6 In humans, it is known to cause subcutaneous and systemic manifestations apart from keratitis and endophthalmitis. 3,[5][6][7] Cutaneous infections are in the form of hyalohyphomycosis with nodules and skin ulcers over extremities in immunocompromised patients with a history of trauma and close contact with plants. 7 It accounts for 1.85% to 3.33% of fungal keratitis.…”

“…3,5 After isolation, differentiation of Colletotrichum from Fusarium species is based on the microbiological appearance. 3,5 Falcate conidia show similarity with Fusarium species, but differentiation is possible on the basis of its aseptate nature and the absence of conidiomata and appressoria. 8 Phylogenetic analysis of the genus Colletotrichum based on the nucleic acid sequence of the internal transcribed spacer region (ITSR) of rDNA was put forth by Cannon et al 5 It reveals that Colletotrichum genus comprises 9 major clades and a number of small clusters and isolated species.…”

“…Colletotrichum is one of the most important phytofungus causing anthracnose disease resulting in spotty leaves and blackening of fruits, usually postharvest but occasionally known to cause subcutaneous, systemic infections and corneal ulcers in humans. 2,3 The genus Colletotrichum is a pigmented fungus of the coelomycetous group. 4 There are various species of Colletotrichum (presently, 66 recognized species), but only 5 have been reported to cause infections in humans, they are Colletotrichum coccoides, Colletotrichum crassipes, Colletotrichum dematium, Colletotrichum gloeosporioides, and Colletotrichum graminicola.…”

“…4 There are various species of Colletotrichum (presently, 66 recognized species), but only 5 have been reported to cause infections in humans, they are Colletotrichum coccoides, Colletotrichum crassipes, Colletotrichum dematium, Colletotrichum gloeosporioides, and Colletotrichum graminicola. 3,5 The species Colletotrichum asianum belongs to the gloeosporioides complex, known to cause anthracnose of Magnifera indica. 5 Here, we report the first 2 cases of human infectious keratitis caused by C. asianum and its risk factors, clinical features, microbiological aspects, and treatment.…”

Filamentous Fungal Keratitis in Taiwan: Based on Molecular Diagnosis

“… 19 , 42 With our limited experience, we found that there were different clinical outcomes between C. gloeosporioides SC and C. truncatum SC; the latter seemed to be more difficult to treat compared to the former. 43 Ten patients with small to medium ulcerations caused by various species infections were not treated with antifungal agents, but the infections resolved, which might be related to the patients’ immune responsiveness, a decrease in organism loading after corneal scraping/keratectomy, and the possible antifungal effects of certain antibiotics. 44 …”