Detection and Molecular characterization of Amoebic Contamination to Contact Lenses as a potential pathogenic threat causing Keratitis in Saudi Arabia

Acanthamoeba spp. is a potentially pathogenic free-living amoeba (FLA) that causes central nervous system infections both in humans and animals and is a significant cause of human keratitis, typically through contaminated water sources, soil and contact lens solutions. The aim of the study was to investigate the contamination rate of contact lenses (CL) and their cleaning solutions with FLA, with a specific focus on Acanthamoeba as a potential health threat to Saudi Arabian contact lens wearers. A total of 105 samples of previously used contact lenses were donated by female students at Shaqra University, Saudi Arabia. Amoebae were isolated through culturing and morphologically identified using standard keys. Molecular identifications based on genus-specific PCR assay were also conducted for all positive cultures. Additionally, genotyping and phylogenetic analysis for Acanthamoeba isolates were performed. Of all the samples, 56.19% were infected with Acanthamoeba and Vahlkampfiidae. Acanthamoeba spp. were detected in 76.3% of the positive cultures (n=45); while Vahlkampfiidae contaminated 27 culture samples either single or mixed infection; including Naegleria sp. Morohological identification revealed five Acanthamoeba species, namely Acanthamoeba castellenii, A. triangularis, A. polyphaga (group II), A. astronyxis (group I) and A. lenticulate (group III). Sequence analysis of the 18S rRNA gene revealed two strains; A castellanii (T4 genotype) and A. polyphagia (T2 genotype). This report highlights the first identification of FLA contamination in contact lenses and cleaning solutions in Saudi Arabia. Efforts are needed to prevent Acanthamoeba contamination, and further studies should investigate potential environmental contamination with pathogenic FLA across Saudi Arabian governorates.