Metagenomic study of acanthamoeba endosymbionts in recreational waters: role in ocular and systemic infections

Acanthamoeba , a free-living amoeba found in recreational waters, is both a pathogen and a host for microbial endosymbionts implicated in human infections, particularly in the eye. This study used metagenomic sequencing to characterize known endosymbionts associated with Acanthamoeba infection in recreational water sites across Miami. Over a three-week sampling period, 51 unique microbial species were identified, with the highest diversity observed at sites with high human activity. Vibrio parahaemolyticus and Pseudomonas aeruginosa - known ocular pathogens and Acanthamoeba endosymbionts - were among the most abundant. Overall, 51% of species were associated with eye infections and 43% were linked to both keratitis and endophthalmitis. As well, 53% of the endosymbionts were associated with skin infections and 47% with respiratory infections. Sites with greater microbial diversity also demonstrated higher numbers of disease-associated species. The frequent detection of Acanthamoeba endosymbionts in popular aquatic settings raises public health concerns, especially for contact lens users who may be at increased risk of ocular infections. Metagenomic surveillance of recreational waters may help inform prevention strategies and reduce the burden of vision-threatening and systemic infections.