Pathogenic Acanthamoeba Griffini Genotype T3 Isolated From a Geothermal Water Park, Malaysia

Free-living amoebae of the genus Acanthamoeba can cause amoebic encephalitis and keratitis infections. Investigations have been conducted to identify the direct and indirect virulence parameters to establish the pathogenic potential of this amphizoic amoeba due to its widespread distribution. The current study sampled ten sites along a stream in Sungai Klah Geothermal Park, Perak, Malaysia, and seven sites showed the presence of Acanthamoeba. Using a combination of morphology examination and molecular analysis, the samples were identified as A. castellanii, A. griffini, A. lenticulate (putative), and A. polyphaga, belonging to genotypes T3 (n = 2), T4 (n = 4) and T5 (n = 1). An isolate SKGP-5, A. griffini genotype T3 exhibited the highest level of cytotoxicity (based on a HeLa cell monolayer assay and detection of secreted serine proteases) and potential pathogenicity as evidenced by tolerance to the temperature of 42°C and 1M mannitol (hyperosmotic solution). This is the first discovery of a pathogenic A. griffini genotype T3 isolate at a public recreational hot spring in Malaysia, indicating the need for regular monitoring of microorganisms that pose a threat to public health in such settings.