Identification and molecular typing of Naegleria fowleri from a patient with primary amebic meningoencephalitis in China

Abstract

Naegleria fowleri is the only Naegleria spp. known to cause an acute, fulminant, and rapidly fatal central nervous system infection in humans called primary amebic meningoencephalitis (PAM). In 2016, a patient with suspected PAM was found in Zhejiang Province of China. The pathogen was identified by microscopic examination and PCR. The positive PCR products were sequenced and the sequences were aligned using the NCBI BLAST program. The homologous and phylogenetic analysis was conducted using MEGA 6 program. On microscopy of direct smears, motile cells with pseudopodia were observed, and the motion characteristics of the pseudopodia as well as the cell morphology suggested that the pathogens were amoeba trophozoites. Wright-Giemsa-stained smears showed amoeba trophozoites of various shapes, which measured 10-25μm in size; these were characterized by a prominent, centrally placed nucleolus and a vacuolated cytoplasm. PCR was negative for Entamoeba histolytica and Entamoeba dispar, but positive for Naegleria spp. and N. fowleri. The nucleotide sequences acquired in this study have been submitted to GenBank with accession numbers KX909928 and KX909927, respectively. The BLAST analysis revealed that the sequences of KX909928 and KX909927 had 100% similarity with the sequence of the N. fowleri gene (KT375442.1). Sequence alignment and the phylogenetic tree revealed that the N. fowleri collected in this study was classified as genotype 2 and was most closely related to Naegleria lovaniensis. This study confirmed N. fowleri as the agent responsible for the infection in this patient. PAM normally progresses rapidly and is generally universally fatal within a week. Unfortunately this patient died at 2 weeks after the onset of symptoms.

Naegleria fowleri: Sources of infection, pathophysiology, diagnosis, and management; a review

“…N. fowleri presence has been confirmed in pond water, swimming pools and sewage canals of India . It was also reported in other countries like China, Hong Kong, Zhejiang, Zambia (Figure ) …”

“…7,22 It was also reported in other countries like China, Hong Kong, Zhejiang, Zambia (Figure 1). 23,24 According to the US Center for Disease Control and Prevention (CDC), the number of PAM cases in the United States from 1962 to 2015 was 138. Recently, in Asian countries, an increase in the number of PAM cases has been investigated.…”

Cartography of Free-Living Amoebae in Soil in Guadeloupe (French West Indies) Using DNA Metabarcoding

“…To determine N. fowleri genotype, the complete ITS region (ITS1, 5.8S, and ITS2) was amplified using the primers described elsewhere [10]. N. fowleri ITS1 sequence was found with a 100% identity with the Genbank accession number # KX909928.1, which corresponds to the genotype type 2 [29] (Table S2).…”

Isolation and Identification of Naegleria Species in Irrigation Channels for Recreational Use in Mexicali Valley, Mexico

“…Death usually occurs within ten to fifteen days of clinical manifestations appearing [ 1 ]. The disease is rare; however, new cases are being reported every year in the world [ 5 , 6 ].…”

“…In Mexico, around 11 cases of PAM have been reported from 1984 to 2007 [ 12 , 13 , 14 , 15 , 16 , 17 ]. Unfortunately, there are many cases underdiagnosed around the world due to lack of awareness of the disease or the similarity of clinical symptoms with other more common central nervous systemdiseases such as bacterial meningitis and viral encephalitis [ 6 , 18 ].…”