Biochemical Criteria of Naegleria Species Isolated from the Egyptian Aquatic Environment

The free-living amoebae Naegleria species (spp.) have been recognized as etiologic agents of amoebic encephalitis, keratitis, otitis, lung lesions and other skin infections mainly in immuno-compromised individuals. In this study, morphological and biochemical characterization of Naegleia strains isolated from the Egyptian aquatic environment were surveyed. Some Naegleria species were cultivated on non-nutrient agar. Isolated strains of Naegleria were identified based on the morphology of trophic and cyst forms in addition to temperature and flagellation test. Biochemical characterization of the isolated amoeba strains using quantitative and qualitative (SDS-PAGE) assays as well as qualitative determination of proteolytic activity in zymograph analysis. Potentially pathogenic free-living amoebae were isolated from all of the examined water sources. Colorimetric assays showed protease activity in heat-tolerant isolates of Naegleria. All pathogenic isolates exhibited higher protease activity than non-pathogenic ones did. The zymographic protease assays showed various banding patterns for different strains of Naegleria.