Abstract
The free-living amoebae Naegleria spp. and Acanthamoeba spp. exist in the natural environment and are sometimes causal agents of lethal primary amoebic meningoencephalitis (PAM), amoebic keratitis (AK) and granulomatous amebic encephalitis (GAE) in humans, respectively. To ascertain the existence of free-living amoebae in Korea, water samples were collected from the Korean hydrosphere, Namhangang (southern Han River), an active location for water skiing and recreation. Samples underwent two-step filtration and were cultured on non-nutrient agar medium with inactivated E. coli. The remaining samples were subjected to PCR for primarily the 18S small ribosomal RNA gene and gene sequencing. Similarities in 18S rDNA sequences, in comparison with various reference amoebae in GenBank, showed 86~99% homology with N. gruberi, N. philippinensis, N. clarki, A. polyphaga, A. castellannii, and Hartmannella (Vermamoeba) vermiformis. Therefore, this study will be useful for seasonal detection of free-living amoebae from various Korean hydrospheres in future studies.
Highlights
The free-living amoebae (FLA) Naegleria spp. and Acanthamoeba spp. are mainly distributed in ponds, rivers, and fresh waters worldwide
FLA cultured from water samples showed a resemblance to the presumed genus Naegleria or Acanthamoeba, as trophozoites showing round pseudopodia or acanthopodia; cysts were observed in the colony (Fig. 4)
A. castellannii (99%), and Hartmannella (Vermamoeba) vermiformis (97%), as which one Yangpyeong sample showed the lowest homology with N. gruberi (86%), and one www.nature.com/scientificreports
Summary
The free-living amoebae (FLA) Naegleria spp. and Acanthamoeba spp. are mainly distributed in ponds, rivers, and fresh waters worldwide. Their existing stages are trophozoite and cyst and additional biflagellate form in in case of Naegleria. In Korea, there has been no case of PAM caused by N. fowleri; yet, one case of GAE due to Acanthamoeba sp. As many people enjoy water-related sports, PAM occurrence has been a social issue through the broadcast media. While it has been reported in many countries, there has not yet been reported in South Korea. A distribution survey was conducted to identify Naegleria and Acanthamoeba species in southern Han River, an active location for water skiing and recreation
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