Balamuthia mandrillaris infection: report of 1st autochthonous,fatal case in Italy

European Journal of Clinical Microbiology & Infectious Diseases -     

Identification of antigenic targets for immunodetection of Balamuthia mandrillaris infection

The free-living amoeba Balamuthia mandrillaris causes granulomatous amoebic encephalitis (GAE) in humans. Rapid identification of balamuthiasis is critical for effective therapeutic intervention and case management. In the present study we identified target antigens for the development of a serological assay for B. mandrillaris infection. We demonstrated by silver staining that protein profiles for all eight isolates of B. mandrillaris, independent of human or animal origin or geographic origin, appeared to be similar except for some minor differences, indicating the molecular homogeneity of these strains. The profiles of all isolates, which ranged from 200 to 10 kDa, were similar, with a prominent protein visible around 30 kDa; all appeared considerably different from protein profiles of the control E6 cells and Acanthamoeba castellanii and Naegleria fowleri isolates. Western blot analysis with rabbit hyperimmune serum identified the major immunodominant antigens of 25, 50, 75, and 80 kDa; positive human sera reacted strongly with proteins around 25, 40, 50, and 75 kDa. Proteins around 40 kDa detected by human serum were not recognized by hyperimmune rabbit serum. None of the target proteins were detected by uninfected control sera. Reactivities of five patients' sera with 4 different isolates of B. mandrillaris (2 strains of human and 2 strains of animal origins) revealed that patients' sera reacted slightly differently with different B. mandrillaris isolates, although major proteins of approximately 25, 50, and 75 kDa were present in all extracts.     

Disseminated Balamuthia mandrillaris Infection

Balamuthia mandrillaris is a rare cause of human infection, but when infections do occur, they result in high rates of morbidity and mortality. A case of disseminated Balamuthia infection is presented. Early diagnosis and initiation of recommended therapy are essential for increased chances of successful outcomes.     

Increasing importance of Balamuthia mandrillaris

Balamuthia mandrillaris is an emerging protozoan parasite, an agent of granulomatous amoebic encephalitis involving the central nervous system, with a case fatality rate of >98%. This review presents our current understanding of Balamuthia infections, their pathogenesis and pathophysiology, and molecular mechanisms associated with the disease, as well as virulence traits of Balamuthia that may be potential targets for therapeutic interventions and/or for the development of preventative measures.     

Diagnostic challenges in Balamuthia mandrillaris infections

Balamuthia mandrillaris is an emerging cause of subacute granulomatous amebic encephalitis (GAE). The diagnosis of this infection has proven to be difficult and is usually made postmortem. Early recognition and treatment may offer some benefit. This report describes a previously healthy woman who died from GAE due to B. mandrillaris.     

Emergence of Balamuthia mandrillaris meningoencephalitis in India

We report two cases of fatal chronic meningoencephalitis caused by Balamuthia mandrillaris in immunocompetent men. Diagnosis of amoebic meningoencephalitis was made ante-mortem in one case and postmortem in another by histopathological examination and confirmed by demonstration of B. mandrillaris deoxyribonucleic acid (DNA) by polymerase chain reaction (PCR).     

Fatal granulomatous amoebic meningoencephalitis due to Balamuthia mandrillaris

Amoebic infections of the central nervous system (CNS) are very rare and usually fatal. A 33-year-old Bolivian male injured his elbow 18 months ago in an accident and, months later, developed multiple skin lesions. He was admitted with confusion, and brain images showed large multifocal lesions with mass effect. Review of the skin biopsy revealed the presence of amoebic trophozoites within a granulomatous inflammation. Despite treatment, he continued to deteriorate and died 17 days after admission. The brain was swollen with prominent uncal herniation, and the leptomeninges showed patchy exudate. Coronal sections revealed widespread hemorrhagic and necrotic lesions. Histology confirmed granulomatous amoebic meningoencephalitis (GAM) with the presence of amoebic trophozoites and occasional cysts. Post-mortem culture confirmed Balamuthia mandrillaris. GAM due to B. mandrillaris may occur in any age group, may or may not be associated with immunosuppression, and is present worldwide. It usually has a subacute and fatal course from hematogenous dissemination of chronic skin or lung lesions.     

Balamuthia mandrillaris and Acanthamoeba amebic encephalitis with neurotoxoplasmosis coinfection in a patient with advanced HIV infection

We describe a patient with advanced HIV infection and Balamuthia mandrillaris and Acanthamoeba amebic encephalitis with Toxoplasma gondii coinfection. A multidisciplinary effort and state-of-the-art diagnostic techniques were required for diagnosis. Our patient is the first reported case of an HIV-infected person with dual Balamuthia mandrillaris and Acanthamoeba amebic encephalitis with neurotoxoplasmosis coinfection.     

The isolation of Balamuthia mandrillaris from environmental sources from Peru

Balamuthia mandrillaris is an opportunistic free-living amoeba that has been reported to cause skin lesions and the fatal Balamuthia amoebic encephalitis (BAE) in humans and other animals. Currently, around 200 human BAE cases have been reported worldwide, although this number is considered to be underestimated. The highest number of BAE cases has been reported in the American continent, mainly in the southwest of the USA. Peru seems to be another hotspot for BAE with around 55 human cases having been identified, usually involving cutaneous infection, especially lesions in the central face area. The isolation of Balamuthia from environmental sources has been reported on only three prior occasions, twice from Californian soils and once from dust in Iran and so it seems that this amoeba is relatively rarely encountered in samples from the environment. We investigated that possibility of finding the amoebae in soil samples from different regions where clinical cases have been reported in Peru. Twenty-one samples were cultured in non-nutrient agar plates and were checked for the presence of B. mandrillaris-like trophozoites and/or cysts. Those samples that were positive for these amoebae by microscopic criteria were then confirmed by PCR amplification and DNA sequencing of the mitochondrial 16S rDNA gene of B. mandrillaris. We have detected the presence of B. mandrillaris in four samples collected in the regions of Piura (3) and Lima (1) where infection cases have been previously reported. We hypothesize that B. mandrillaris is present in Peru in soil and dust which therefore constitutes a source of the infection for the BAE cases previously reported in this country. Further studies should be carried out in the area to confirm the generality of this finding.     

Environmental isolation of Balamuthia mandrillaris associated with a case of amebic encephalitis

This report describes the first isolation of the ameba Balamuthia mandrillaris from an environmental soil sample associated with a fatal case of amebic encephalitis in a northern California child. Isolation of the ameba into culture from autopsied brain tissue confirmed the presence of Balamuthia: In trying to locate a possible source of infection, soil and water samples from the child's home and play areas were examined for the presence of Balamuthia: The environmental samples (plated onto nonnutrient agar with Escherichia coli as a food source) contained, in addition to the ameba, a variety of soil organisms, including other amebas, ciliates, fungi, and nematodes, as contaminants. Presumptive Balamuthia amebas were recognized only after cultures had been kept for several weeks, after they had burrowed into the agar. These were transferred through a succession of nonnutrient agar plates to eliminate fungal and other contaminants. In subsequent transfers, axenic Naegleria amebas and, later, tissue cultures (monkey kidney cells) served as the food source. Finally, the amebas were transferred to cell-free axenic medium. In vitro, the Balamuthia isolate is a slow-growing organism with a generation time of approximately 30 h and produces populations of approximately 2 x 10(5) amebas per ml. It was confirmed as Balamuthia by indirect immunofluorescence staining with rabbit anti-Balamuthia serum and human anti-Balamuthia antibody-containing serum from the amebic encephalitis patient. The environmental isolate is similar in its antimicrobial sensitivities and identical in its 16S ribosomal DNA sequences to the Balamuthia isolate from the deceased patient.     

Autopsy case of amebic granulomatous meningoencephalitis caused by Balamuthia mandrillaris in Japan

Balamuthia mandrillaris is a free-living ameba that causes amebic encephalitis. Herein, we report an autopsy case of Balamuthia encephalitis proven with polymerase chain reaction (PCR) and immunohistochemistry from paraffin-embedded brain biopsy specimens. A 68-year-old Japanese male presented at a hospital with progressive right hemiparesis approximately 3 months before his death. An open-brain biopsy specimen showed diffuse meningitis with massive coagulative necrosis. The perivascular spaces contained numerous lymphocytes, histiocytes and giant cells, although the etiology was not determined. The patient deteriorated into coma and died from cerebral herniation. Autopsy revealed abundant trophozoites and cysts in the subarachnoid and Virchow-Robin's spaces. Electron-micrographs of the amebic cysts showed a characteristic triple-walled envelope. The amebas were identified as Balamuthia mandrillaris based on immunohistochemical analysis from the autopsy and biopsy specimens. Primer sets designed to amplify approximately 200 bp bands of mitochondrial 16S rRNA gene of Balamuthia by PCR produced positive results from the biopsy specimens but negative results from the autopsy specimens. In summary, PCR to amplify shorter segments of DNA may be of diagnostic value in detecting suspected cases of balamuthiasis in formalin-fixed, paraffin-embedded specimens. Increased awareness and timely diagnosis of Balamuthia encephalitis might lead to earlier initiation of therapy and improved outcome.     

First report of the isolation of Balamuthia mandrillaris in the northern region of Japan

Parasitology Research - Balamuthia mandrillaris is a free-living amoeba that lives in soil and water near human settlements. B. mandrillaris was first isolated from a mandrill baboon that died at...     

Multiplex real-time PCR assay for simultaneous detection of Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria fowleri

Infections caused by Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris occur throughout the world and pose many diagnostic challenges. To date, at least 440 cases of severe central nervous system infections caused by these amebas have been documented worldwide. Rapid and specific identification of these free-living amebas in clinical samples is of crucial importance for efficient case management. We have developed a triplex real-time TaqMan PCR assay that can simultaneously identify Acanthamoeba spp., B. mandrillaris, and N. fowleri in the same PCR vessel. The assay was validated with 22 well-characterized amebic strains harvested from cultures and nine clinical specimens that were previously characterized by in vitro culture and/or immunofluorescence assay. The triplex assay demonstrated high specificity and a rapid test completion time of less than 5 h from the reception of the specimen in the laboratory. This assay was able to detect one single ameba per sample analyzed, as determined with cerebrospinal fluid spiked with diluted cultured amebas. This assay could become useful for fast laboratory diagnostic assessment of amebic infections (caused by free-living amebas) in laboratories with adequate infrastructure to perform real-time PCR testing.     

Balamuthia mandrillaris meningoencephalitis in an immunocompetent patient: an unusual clinical course and a favorable outcome

Balamuthia mandrillaris meningoencephalitis is a rare but often fatal infection; only 2 survivors have been reported to date worldwide. We report the case of an apparently immunocompetent patient (72-year-old woman) who developed several episodes of seizures without prior history of respiratory or skin infections. Magnetic resonance imaging with contrast revealed 2 ring-enhancing lesions, one in the right precentral region and the other in the left posterotemporal region. Open biopsy revealed Balamuthia encephalitis. The patient was treated with combination antibiotics (pentamidine, 300 mg intravenously once a day; sulfadiazine, 1.5 g 4 times a day; fluconazole, 400 mg once a day; and clarithromycin, 500 mg 3 times a day) and was discharged home. There have been no significant neurological sequelae at this writing (6 months after biopsy). We present this case with unusual clinical course to raise awareness of this infectious disease, which may have a more favorable outcome if diagnosed and treated in its early states.     

Isolation and molecular characterization of Acanthamoeba and Balamuthia mandrillaris from combination shower units in Costa Rica

Free living amoebae (FLA) are ubiquitous protozoa, which may behave as parasites under certain conditions. Four genera are recognized as causal agents of infections in humans and animals: Naegleria, Sappinia, Acanthamoeba and Balamuthia. This work determines the presence of FLA in combination shower units and employs molecular biology for the characterization of isolates. The morphological analysis and partial sequencing of the 18S rDNA gene revealed the presence of Acanthamoeba genotype T4 in 30 % of the units sampled. In addition to Acanthamoeba cysts, trophozoites with morphological characteristics similar to Balamuthia were identified. PCR assay using the mitochondrial 16S rRNA gene as a target confirmed the identification of the amoeba as Balamuthia mandrillaris. Up to date, this is the first report of the isolation of B. mandrillaris in Central America and the fifth report worldwide.     

Balamuthia amoebic encephalitis: an emerging disease with fatal consequences

Balamuthia amoebic encephalitis (BAE), caused by the protozoan pathogen, Balamuthia mandrillaris, is a serious human disease with fatal consequences and a mortality rate of more than 95%. A key factor that contributes to the high mortality is the incomplete understanding of its pathogenesis and pathophysiology. The most distressing aspect is that the high level of mortality is due to lack of awareness combined with the lack of effective drugs. Early diagnosis followed by aggressive treatment may lead to cure. Several lines of evidence suggest that BAE develops as a result of haematogenous spread, but it is unclear how circulating amoebae enter the central nervous system and cause inflammation, blood-brain barrier disruption and neuronal injury. Recent studies have identified several parasite-host determinants for B. mandrillaris translocation of the blood-brain barrier, and host inflammatory markers that may be associated with neuronal injury. These determinants may provide important targets for the prevention and treatment of BAE. Here, we present a brief overview of the current understanding of the pathogenesis and pathophysiology of BAE, available diagnostic methods, possible therapeutic interventions and biology of the causative agent.