Non-traumatic keratitis due to Colletotrichum truncatum

First report of human infection caused by Colletotrichum chlorophyti occurring in a post-corneal transplant patient with endophthalmitis

Keratomycosis or mycotic keratitis is recognized as one of the major causes of ophthalmic morbidity worldwide. The most common organisms linked to keratomycosis include Candida spp., Fusarium spp., and Aspergillus spp. However, varieties of saprobic fungi have been reported as causative agents of keratomycosis. Amongst these are members of the genus Colletotrichum. Herein we present the first reported case of C. chlorophyti infection in a post-corneal transplant patient, suggesting an increasing role for Colletotrichum species as emerging human pathogens, particularly in the transplant population.

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

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.