Ocular Microbiology and Immunology Group
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2025 OMIG Abstract

Characterization of Endosymbiotic Microbiota, Mycotoxigenic Potential, and Metabolic Profiles of Fusarium Keratitis Isolates: Correlation with Clinical Outcomes

Salomon Merikansky^1-3, Alexander Alfonso¹, Beatriz Munoz¹, Maribel Hernandez¹, Jorge Maestre¹,
Heather Durkee³, Juan Carlos Navia³, Mariela C. Aguilar³, Jean Marie Parel³, Eduardo C. Alfonso^1,2,
Harry W. Flynn^1,2, Guillermo Amescua^1-3, Darlene Miller<sup>1,2

1</sup>Ocular Microbiology Laboratory, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida; ²Anne Bates Leach Eye Center, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida; ³Ophthalmic Biophysics Center, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida

Purpose: To characterize the presence and diversity of endosymbiotic bacterial communities (microbiota), mycotoxigenic profiles, and metabolic functional profiles of clinical Fusarium isolates, and to correlate these findings with clinical outcomes in patients with Fusarium keratitis.

Methods: Ten clinical Fusarium isolates were analyzed using PCR and whole genome sequencing (CosmosID) to identify fungal species and associated microbial endosymbionts. PCR was also used to detect mycotoxin biosynthesis genes, specifically the fumonisin gene FUM1. Functional diversity and carbon metabolism were evaluated in three representative isolates using Biolog EcoPlates. Microbiological and metabolic findings were correlated with corresponding clinical outcomes.

Results: Nine of the ten isolates belonged to the Fusarium solani species complex, including F. keratoplasticum and F. oxysporum; one was identified as F. petroliphilum. Sequencing revealed six distinct bacterial phylotypes comprising 86 species. These were grouped into phyla: Actinobacteriota (n=16, most prevalent), Bacillota (n=12), Pseudomonadota (n=10), Bacteroidota (n=5), and Fusobacteriota (n=1). FUM1 gene was detected in 4 samples. Functional metabolic profiles and carbon utilization patterns varied by fungal isolate and growth environment. Isolates harboring a higher number of bacterial endosymbionts and those carrying FUM1 were both associated with worse clinical outcomes.

Conclusions: Fusarium species may harbor diverse bacterial endosymbionts and mycotoxin-producing genes that contribute to pathogenicity and poor clinical outcomes. These microbial interactions should be considered in the management of recalcitrant Fusarium keratitis. Characterizing fungal-associated microbiota may offer new strategies for diagnosis and treatment.