Insights Into the Genetic Diversity of Acanthamoeba Keratitis: A Clinical and Molecular Study.

PURPOSE: To characterize Acanthamoeba isolates from patients with Acanthamoeba keratitis (AK) at the subgenotypic level, and to determine the distribution of genotypes and subgenotypes associated with clinical infections.

METHODS

Corneal scrapings from clinically diagnosed patients with AK were subjected to molecular genotyping. DNA was extracted and amplified using PCR targeting the 18S ribosomal RNA gene. Sequencing data were analyzed, and phylogenetic trees were constructed using MEGA X software to determine species, genotypes, and subgenotypes.

RESULTS

Eight species of Acanthamoeba were identified: Acanthamoeba castellanii (38%), Acanthamoeba culbertsoni (25%), Acanthamoeba polyphaga (13%), Acanthamoeba hatchetti (6%), Acanthamoeba triangularis (6%), Acanthamoeba jacobsi (6%), Acanthamoeba healyi (3%), and Acanthamoeba spp. (3%). Genotypic analysis revealed 4 major genotypes: T4 (72%), T10 (19%), T12 (3%), and T15 (6%). The predominant T4 genotype was further classified into 5 subgenotypes: T4A, T4B, T4C, T4D, and T4F.

CONCLUSIONS

This study highlights the genetic diversity of Acanthamoeba in AK cases, with a predominance of the T4 genotype and its subgenotypes. Subgenotypic classification provides enhanced resolution in molecular epidemiology and may contribute to understanding pathogenicity and clinical outcomes in AK.