Nona Semana Integrada do Instituto de Física de São Carlos

Naegleria spp. Diversity on Monjolinho River Basin – São Carlos, State of São Paulo

Não agendado

20m

Doutorado

Palestrante

Sra NATÁLIA KARLA BELLINI (Physics and informatics department, Physics Institute of Sao Carlos, University of Sao Paulo - USP, Sao Carlos, SP, Brazil)

Descrição

Naegleria spp. has been one of the most studied genera among the Free Living Amoeba (FLA) group due to its thermophilic characteristic and for N. fowleri being a pathogenic species, capable of causing human encephalitis.(1) Named Primary Amoebic Meningoencephalitis (PAM), the disease faces two main drawbacks: difficulty in diagnosis and lack of an efficient treatment (2) resulting in more than 95% fatality of infection.(3) As a free living organism it can be found in water and soil, so the knowledge of its geographical distribution is critical to better comprehend its niche and to prevent new contamination cases. Besides, by mapping Naegleria spp. diversity it is possible to access evolutionary patterns revealing relationships among them. Considering the lack of Brazilian studies on Naegleria spp. environmental distribution, this PhD research aims to characterize its diversity in the Monjolinho River Basin, São Carlos-SP. The methodology includes water collection in five sampling sites, limnological analysis to determine eutrophication along the river, culture of the isolates on non-nutrient agar (NNA) plates, thermo tolerance assay to search thermophilic pathogenic species, DNA extraction, 18S rDNA sequencing and phylogenetic tree reconstruction. Through culture on NNA plates, the amoeba growth was observed in all sampling sites. In association with sequencing results, five Naegleria species could be found: N. australiensis, N. philippiniensis, N. gruberi, N. dobsoni, and N. canariensis, besides Valkampfia. At the most eutrophic site four of the six amoebas identified in this work were present. Regarding the thermo tolerance assay, solely N. australiensis could withstand $44^{\circ}$C. In contrast with earlier literature reports, our result revealed an increase in the maximum temperature that N. australiensis tolerates. Although human pathogenic species did not occur in this collection, the presence of N. australiensis and N. philippinensis, both capable of causing brain infection in animal models, represent a warning to animals surrounding river. This work contributes to the understanding of the amoeba distribution in Brazil.

Referências

1 ONG, T.Y.Y.; KHAN, N.A.; SIDDIQUI, R. Brain-eating amoebae: Predilection sites in the brain and disease outcome. Journal Clinical Microbioogy,v.55, n.7, p.1989-1997,2017.doi:10.1128/JCM.02300-16.
2 BELLINI, N.K;, SANTOS, T.M.; SILVA, M.T.A.; THIEMANN, O.H.The theapeutic strategies against Naegleria fowleri. Experimental Parasitoogy, v.187, p.1-11,2018. doi:10.1016/j.exppara.2018.02.010.
3 DE JONCKHEERE, J.F. Origin and evolution of the orldwide distributed pathogenic amoeboflagellate Naegleria fowleri. Infection Genetic in Evolution, v.11,n.7, p.1520–1528,2011. doi:10.1016/j.meegid.2011.07.023.