The First Molecular Genotyping of Causing Primary Amebic Meningoencephalitis in Thailand With Epidemiology and Clinical Case Reviews.

Primary amebic meningoencephalitis (PAM) is a rare and fatal central nervous system infection caused by , a free-living amoeba found in the environment. To date, eight pathogenic genotypes have been reported worldwide. We aimed to explore the genotypes of that cause primary amebic meningoencephalitis in Thailand. In 2021, the 17th PAM case was reported, and a retrospective literature search of PAM cases in Thailand from 1982 through April 2021 was performed. Phylogenetic and genotyping analyses of the two mitochondrial (12S rRNA and 16S rRNA) and nuclear (ITS1 and 5.8s rRNA) genes of were performed on four available clinical isolates. Based on the mitochondrial and nuclear genes, genotype T3 was found to cause PAM in three out of four cases. However, disagreement between the genotype based on the mitochondrial and nuclear genes was found in one of the PAM cases, in which the 12S rRNA locus suggested the causative genotype as T1, while the ITS1 implied genotype T4. The discrepancy between the mitochondrial and nuclear genome was previously observed, which suggests the possible horizontal gene transfer among species. Based on the ITS1 gene, two genotypes, T3 and T4, were found to be the genotypes causing PAM in this study. In addition, genotype T2 was previously reported in a traveler who was infected in Thailand. Thus, at least three genotypes (T2, T3, and T4) of are found to be associated with PAM in Thailand.