Cell surface differences of Naegleria fowleri and Naegleria lovaniensis exposed with surface markers

Lectins as virulence factors in Entamoeba histolytica and free-living amoebae

Currently, there is growing interest in the identification and purification of microbial lectins due to their involvement in the pathogenicity mechanisms of pathogens, such as Entamoeba histolytica and free-living amoebae. The Gal/GalNAc lectin from E. histolytica participates in adhesion, cytotoxicity and regulation of immune responses. Furthermore, mannose- and galactose-binding protein have been described in Acanthamoeba castellanii and Balamuthia mandrillaris, respectively and they also contribute to host damage. Finally, in Naegleria fowleri, molecules containing mannose and fucose are implicated in adhesion and cytotoxicity. Considering their relevance in the pathogenesis of the diseases caused by these protozoa, lectins appear to be promising targets in the diagnosis, vaccination and treatment of these infections.

Isolation and Molecular Identification of Naegleria australiensis in Irrigation Water of Fuerteventura Island, Spain

INTRODUCTION

Saline groundwater desalination has recently emerged as an alternative source of irrigation water in arid and semiarid regions due to the gradual reduction in the quantity and quality of conventional water resources for agricultural use. In Fuerteventura Island (Spain), an extremely arid territory in the European Union, brackish water desalination is one of the few available water sources for agricultural production. Very little research has been conducted on the microbiological quality of this water mainly used for irrigation of vegetable crops. Free-living amoebae (FLA) are widely distributed protozoa in the environment and have been isolated from many environmental sources such as dust, soil and water. Among the pathogenic genera included in this group, Acanthamoeba spp., Naegleria fowleri and Balamuthia mandrillaris have been reported to be causative agents of lethal encephalitis, disseminated infections and keratitis. Particularly, Naegleria fowleri is a pathogenic FLA species which causes primary amoebic meningoencephalitis (PAM).

MATERIALS AND METHODS

In the present study, the presence of pathogenic FLA strains on desalinated brackish water samples for irrigation has been evaluated during 7 months.

RESULTS

From the analysed samples, only one was positive for Naegleria australiensis. This is the first report of Naegleria spp. in desalinated brackish water for irrigation in Spain.

Biology and pathogenesis of Naegleria fowleri

Naegleria fowleri is a protist pathogen that can cause lethal brain infection. Despite decades of research, the mortality rate related with primary amoebic meningoencephalitis owing to N. fowleri remains more than 90%. The amoebae pass through the nose to enter the central nervous system killing the host within days, making it one of the deadliest opportunistic parasites. Accordingly, we present an up to date review of the biology and pathogenesis of N. fowleri and discuss needs for future research against this fatal infection.

Survey of Naegleria and its resisting bacteria-Legionella in hot spring water of Taiwan using molecular method

Naegleria is a free-living amoebae existing in soil and aquatic environments. Within the genus Naegleria, N. fowleri is most recognized as potential human pathogen causing primary amoebic meningoencephalitis (PAM). Furthermore, the Naegleria spp. can serve as vehicles for facultative pathogens, such as Legionella. In this study, we identified Naegleria and Legionella based on the PCR amplification with a genus-specific primer pair and investigated the distribution of Naegleria and Legionella at five spring recreation areas in Taiwan. In this study of hot spring and other water sources in Taiwan, five Naegleria spp. were detected in 15 (14.2%) of the water samples. The most frequently detected was N. lovaniensis (n = 6), followed by N. australiensis (n = 5), and then N. clarki (n = 2). N. americana and N. pagei were detected once, respectively. The pathogenic species N. fowleri was not detected; however, N. australiensis considered to be a potential pathogen species in humans was found. Legionella spp., an endosymbiont of Naegleria, was detected in 19 (17.9%) of the water samples in this study. Overall, 5.7% of the water samples contained both Naegleria and Legionella. The Legionella spp. identified were L. pneumophila and L. erythra. Results of this survey confirm the existence of Naegleria and Legionella in Taiwan spring recreation areas. It should be considered a potential threat for health associated with human activities in spring recreation areas of Taiwan.