Genetic diversity of Acanthamoeba and clinical outcome predictors in Danish patients with Acanthamoeba keratitis.

Purpose: Acanthamoeba keratitis (AK) is a severe corneal infection with potential detrimental effects on visual outcome and quality of life, primarily affecting young contact lens wearers. We report Acanthamoeba genotypes, subtypes and clinical outcome from Danish patients with AK.

Methods: Thirty-nine PCR-positive AK cases diagnosed and treated at Aarhus University Hospital, Denmark, from 2002 to 2022 were included. Corneal samples underwent next-generation sequencing (NGS) for Acanthamoeba genotyping. These data were compared with clinical data and results from PCR.

Results: Acanthamoeba T4 was the most frequent genotype (n = 35), with four subtypes identified (T4A, T4B, T4D and T4G); three cases of the T3 genotype were observed. Three samples showed evidence of two distinct Acanthamoeba sequences. The median patient age was 35 years, genders were equally represented and the median time from symptom onset to diagnosis was 26 days. Ninety per cent had identifiable risk factors in addition to contact lens wear. Corticosteroid treatment prior to AK diagnosis, moderate-to-severe pain, male gender, older age, ring infiltration and infiltrate size >3 mm were associated with poor visual outcome. No significant correlation was found between Acanthamoeba genotype or subtype and clinical outcomes.

Conclusion: We reveal the genetic diversity of Acanthamoeba involved in AK in Denmark. However, genotype or subtype did not predict clinical outcome. Further research is needed to clarify the role of specific genotypes and subtypes in disease progression and treatment response.