A pediatric case of primary amoebic meningoencephalitis due to Naegleria fowleri diagnosed by next-generation sequencing of cerebrospinal fluid and blood samples

Background Primary amoebic meningoencephalitis (PAM) is a rare, acute and fatal disease of the central nervous system caused by infection with Naegleria fowleri (Heggie, in Travel Med Infect Dis 8:201–6, 2010). Presently, the majority of reported cases in the literature have been diagnosed through pathogen detection pathogens in the cerebrospinal fluid (CSF). This report highlights the first case of pediatric PAM diagnosed with amoeba infiltration within CSF and bloodstream of an 8-year-old male child, validated through meta-genomic next-generation sequencing (mNGS). Case presentation An 8-year-old male child was admitted to hospital following 24 h of fever, headache and vomiting and rapidly entered into a coma. CSF examination was consistent with typical bacterial meningitis. However, since targeted treatment for this condition proved to be futile, the patient rapidly progressed to brain death. Finally, the patient was referred to our hospital where he was confirmed with brain death. CSF and blood samples were consequently analyzed through mNGS. N. fowleri was detected in both samples, although the sequence copy number in the blood was lower than for CSF. The pathogen diagnosis was further verified by PCR and Sanger sequencing. Conclusions This is the first reported case of pediatric PAM found in mainland China. The results indicate that N. fowleri may spread outside the central nervous system through a damaged blood–brain barrier.

Primary Amoebic Meningoencephalitis by Naegleria fowleri: Pathogenesis and Treatments

Naegleria fowleri is a free-living amoeba (FLA) that is commonly known as the “brain-eating amoeba.” This parasite can invade the central nervous system (CNS), causing an acute and fulminating infection known as primary amoebic meningoencephalitis (PAM). Even though PAM is characterized by low morbidity, it has shown a mortality rate of 98%, usually causing death in less than two weeks after the initial exposure. This review summarizes the most recent information about N. fowleri, its pathogenic molecular mechanisms, and the neuropathological processes implicated. Additionally, this review includes the main therapeutic strategies described in case reports and preclinical studies, including the possible use of immunomodulatory agents to decrease neurological damage.

Free Living Amoebic Infections: Review

Infections caused by Naegleria fowleri , Acanthamoeba spp., and Balamuthia mandrillaris result in a variety of clinical manifestations in humans. These amoebae are found in water and soil worldwide. Acanthamoeba spp. and B. mandrillaris cause granulomatous amoebic encephalitis, which usually presents as a mass, while N. fowleri causes primary amoebic meningoencephalitis. Acanthamoeba spp. can also cause keratitis, and both Acanthamoeba spp. and B. mandrillaris can cause lesions in skin and respiratory mucosa. These amoebae can be difficult to diagnose clinically as these infections are rare and, if not suspected, can be misdiagnosed with other more common diseases. Microscopy continues to be the key first step in diagnosis but the amoeba can be confused with macrophages or other infectious agents if an expert in infectious disease pathology or clinical microbiology is not consulted. Although molecular methods can be helpful in establishing the diagnosis, these are only available in referral centers. Treatment requires combination of antibiotics and antifungals and, even with prompt diagnosis and treatment, mortality for neurological disease is extremely high.

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

Members of the genus Naegleria are free-living amoebae that are widely distributed in water and soil environments. Moreover, Naegleria fowleri is a pathogenic amoeba species that causes a fatal disease in the central nervous system known as primary amoebic meningoencephalitis (PAM) in humans. Since most reported infections due to N. fowleri are reported in recreational waters worldwide, this study was aimed to describe the presence of these amoebic genus in Mexicali Valley irrigation channels of recreational use. A total of nine water samples were collected and processed by triplicate, in nine different sites of the Valley. After filtering and culturing the samples, plates were examined, and the observed amoebae were morphologically identified at the genus level. In addition, the pathogenicity of these amoebic isolates was checked, and molecular characterization was performed by PCR/sequencing. The results revealed the presence of Naegleria spp. in all the channels sampled. Finally, molecular identification confirmed the presence of five different species of Naegleria: N. fowleri, N. australiensis, N. gruberi, N. clarki and N. pagei. The presence of these protists, particularly N. fowleri, should be considered as a potential human health risk in the region.

A Fatal Case of Primary Amoebic Meningoencephalitis (PAM) Complicated with Diabetes Insipidus (DI): A Case Report and Review of the Literature

Naegleria fowleri is a highly infective free-living amoeba usually isolated from soil and fresh water and is primarily found to infect the central nervous system (CNS) resulting in primary amoebic meningoencephalitis (PAM). PAM as a cause of meningitis is often overlooked for other, more common causes of meningitis. Despite all the advances in antimicrobial therapy and supportive care systems, the mortality rate of this rare infection remains above 95% with the bulk of the cases being found in developed countries. We are presenting a case of a 44-year-old male with fever, worsening headache, and generalized weakness. Lumbar puncture showed a raised leucocyte count of 1100/µL with predominant polymorphonuclear cells, and wet mount prep for Naegleria fowleri was positive further confirmed with PCR. The patient was started Intravenous (IV) and intrathecal amphotericin-B, Per Oral (PO) miltefosine, IV rifampin, IV fluconazole, and IV dexamethasone. However, the patient started producing urine at 300–500 ml/hour. The patient’s sodium levels increased from 144 to 175 mmol/L in 12 hours with raised serum osmolality and decreased urine osmolality and urine sodium. The patient was started on PO desmopressin of 0.2 micrograms twice daily after which his urine output dropped to 60–80 ml/hour and sodium decreased from 175 to 162 and, later 155 mmol/L; however, the patient expired. PAM is a rare and extremely fatal illness, but with increasing incidence now being reported in developing countries as a result of better diagnostics. DI is a very rare complication reported in these patients leading to poor outcome. The complication of diabetes insipidus (DI) has not been extensively studied in patients having PAM. Only three cases have been reported with this complication. No mechanism has been mentioned in the literature behind the development of DI in these patients, and no study has mentioned laboratory details of DI as mentioned in this report.