Work

Isolate-level pathogenic heterogeneity in keratitis caused by the Fusarium solani species complex: corneal invasion, host immunopathology, and model fidelity

Year: 2026

Type: review

Abstract: species complex (FSSC) often progresses despite antifungal therapy and can result in irreversible visual loss. Yet biological diversity within FSSC has not been integrated across taxonomy, isolate phenotype, corneal models, host response, and clinical outcome. This Review synthesizes taxonomic, experimental, and clinical evidence on isolate-level variation in adhesion, epithelial entry, stromal invasion, biofilm formation, tissue damage, immune activation, and antifungal response. Available data support substantial isolate-dependent heterogeneity but do not justify a stable species- or member-level ranking of clinical severity. Fungal developmental state, inoculation route, epithelial integrity, stromal architecture, host immunity, treatment timing, and tissue drug exposure all modify the phenotype observed. Cell, tissue, animal, and human-specimen models therefore provide complementary rather than interchangeable evidence, and few studies carry the same authenticated clinical isolate from corneal testing to longitudinal patient outcomes. Refractory FSSC keratitis is best investigated through a matched isolate-model-patient approach integrating multilocus authentication, spatial fungal localization, viable burden, host-mediated injury, compartment-specific drug exposure, and prespecified clinical endpoints. Such designs could distinguish persistent infection from inadequate tissue exposure and immunopathology and thereby improve risk stratification and therapeutic development.

Source: Frontiers in Cellular and Infection Microbiology

DOI: 10.3389/fcimb.2026.1984688