Genotyping and Molecular Identification of Acanthamoeba Genotype T4 and Naegleria fowleri from Cerebrospinal Fluid Samples of Patients in Turkey: Is it the Pathogens of Unknown Causes of Death?

Purpose: This study was aimed to investigate the presence of pathogenic free-living amoebae (FLA) in suspected cases of meningoencephalitis with unknown causes of death in Turkey.

Method: A total of 92 patients, who were diagnosed as meningoencephalitis, were enrolled. All cerebrospinal fluid (CSF) samples were directly microscopically examined and cultured. Acanthamoeba, N. fowleri and B. mandrillaris were further investigated using molecular diagnostic tools including real-time PCR, sequencing, and phylogenetic analyses.

Results: The examined CSF samples were not found positive for the presence of FLA by microscopic examination and culture method. However, two CSF samples were detected positive by real-time PCR assay. Of the positive CSF samples, one was identified as Acanthamoeba genotype T4 and the second positive sample was identified as N. fowleri belonging to genotype II. Furthermore, the pathogens diagnoses was verified through Sanger sequencing.

Conclusion: This study was significant to report the presence of Acanthamoeba genotype T4 and N. fowleri genotype II in CSF samples by real-time PCR assay. The present study shows the significance of primary amoebic meningoencephalitis (PAM) and granulomatous amoebic encephalitis (GAE) as one of the differential diagnoses to be considered by clinicians during the evaluation of suspected meningoencephalitis or cases of unknown cause in Turkey. Using real-time PCR, this has made the rapid detection, in a short time-frame, of Acanthamoeba and N. fowleri in CSF samples from patients. The problems with qPCR is that it is not available in every laboratory, reagents are expensive, and it requires skilled and expert personnel to set up these assays.