ABSTRACT
Objective: To determine the morphological and molecular characterization of Acanthamoeba isolates from contact lens paraphernalia in Malaysia and to investigate their pathogenic potential based on the physiological tolerance. Methods: One hundred and eighty contact lens wearers donated their contact lens, lens storage cases and lens solutions between 2018 and 2019. The samples were inoculated onto 1.5% non-nutrient agar plates for 14 d. Polymerase chain reaction (PCR) was performed and the amplified PCR products were sequenced and compared with the published sequences in GenBank. The pathogenic potential of positive isolates was further tested using temperature-tolerance and osmo-tolerance assays. Acanthamoeba species were categorized into three distinct morphological groups established by Pussard and Pons. Results: Acanthamoeba was successfully isolated from 14 (7.8%) culture-positive samples in which 11 belong to morphological group II and 3 belong to morphological group III, respectively. The sequencing of 18S ribosomal RNA gene led to the identification of the T4 genotype in all the isolated strains. In vitro assays revealed that 9 (64.3%) Acanthamoeba isolates were able to grow at 42 °C and 1 M mannitol and were thus considered to be highly pathogenic. Conclusions: To the best of our knowledge, this is the first report identifying the Acanthamoeba genotype and their pathogenic potential among contact lens wearers in Malaysia. The potentially pathogenic T4 genotype isolated in this study is the most predominant genotype responsible for human ocular infection worldwide. Hence, increasing attention should be aimed at the prevention of contamination by Acanthamoeba and the disinfection of contact lens paraphernalia.
ABSTRACT
The present study was conducted to investigate the clinical outcomes of Entamoeba histolytica infection in symptomatic and asymptomatic Orang Asli (aborigine) communities in Malaysia. Examination was performed on 500 stool samples obtained from Orang Asli communities in 3 different states using formalin-ether concentration, trichrome staining, and single-round PCR techniques. Out of 500 stool samples, single infection of E. histolytica, Entamoeba dispar, and Entamoeba moshkovskii was identified in 3.2%, 13.4%, and 1%, respectively. In addition, 10 samples had mixed infections with E. histolytica and E. dispar. Six samples containing E. dispar were also positive for E. moshkovskii, and only 2 samples had E. histolytica in association with E. dispar and E. moshkovskii. Seventeen E. histolytica-positive samples were from symptomatic subjects, whereas the remaining 11 samples came from asymptomatic subjects. These findings suggest a predominant distribution of pathogenic potential of E. histolytica strains in this community. Therefore, further studies on genotyping of E. histolytica is required, to find out association between E. histolytica genotype and the outcome of the infection.