Molecular characterization of Acanthamoeba isolated from contact lens paraphernalia: An evidence of potentially pathogenic T4 genotype in Malaysia

Abstract

Background: Amphizoic amoebae generate a serious human health threat due to their pathogenic potential as facultative parasites, causative agents of vision-threatening Acanthamoeba keratitis (AK). Recently, AK incidences have been reported with increasing frequency worldwide, particularly in contact lens wearers. Therefore, this study was designed to identify the genotypes and investigate the pathogenic potential of Acanthamoeba isolates. Methods & Materials: A cross-sectional study was conducted among 180 volunteers who provided their contact lenses, lens storage case and lens solution between 2018 and 2019. All samples were inoculated onto 1.5% non-nutrient agar plates overlaid with Escherichia coli and incubated at 30 °C for 14 days. Polymerase chain reaction was performed on positive isolates and the amplified products were sequenced and compared with GenBank Data. Pathogenic potential of positive isolates were further tested with thermo- and osmo-tolerance assays. Results: Acanthamoeba was successfully isolated from 14 (7.8%) culture-positive samples. Analysis of 18S ribosomal RNA gene indicated that all sequenced positive isolates shared 98–100% homology with Acanthamoeba genotype T4. In vitro assays revealed that 9 (64.2%) Acanthamoeba isolates are able to grow at 42 °C and 1.0 M, indicated a highly pathogenic strain. Conclusion: This is the first report of genotypic identification of Acanthamoeba from contact lens paraphernalia in Malaysia. Potentially pathogenic T4 genotype isolated in this study is the most prevalent genotype in human ocular infection worldwide. Hence, this information would be useful in selecting suitable strain to develop immunological and/or molecular diagnostic assays in the future.