A case of fatal amoebic encephalitis caused by Balamuthia mandrillaris, China

We reported a case of B.mandrillaris amoebic encephalitis in mainland China. Metagenomics next-generation sequencing helped initial diagnosis and then polymerase chain reaction of the B.mandrillaris in the infected nasal skin tissues reported positive and amoeba cysts were found in the tissue under microscopic observation.

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

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 the San Diego Zoo Wildlife Park in California in 1986, and the first human infection was reported in 1990. Although reported B. mandrillaris infections are often not properly characterized, it appears that B. mandrillaris invades the living body from the soil and water, either via a wound or the nasal cavity. Most confirmed infections have originated in South and North America. B. mandrillaris inhabits warm climates and is recognized as a pathogen in warm areas such as desert climates and tropical climates. B. mandrillaris has been isolated from environmental samples since 2000, most of which originated from warm areas such as step climates, tropical climates, and desert climates. However, B. mandrillaris may survive in diverse environments, although fewer granulomatous amebic encephalitis patients have been reported in colder Japanese and Northern European regions. In the present study, we conducted a survey of 13 soil samples in Aomori Prefecture located at the northernmost tip of Japan Honshu and successfully isolated one strain of B. mandrillaris from soil for the first time in Japan. In addition, B. mandrillaris gene was detected from several soils. This confirms that B. mandrillaris is capable of spreading to a wider climatic region.

Canine amoebic meningoencephalitis due to Balamuthia mandrillaris

A 1-year-old Siberian Husky dog with acute-onset of seizures, recumbency, paddling, and muscular fasciculations was autopsied. A locally extensive hemorrhagic and malacic focus was noted in the right cerebral frontal cortex, and severe necrotizing and hemorrhagic, neutrophilic meningoencephalitis was diagnosed microscopically. Amoebic trophozoites and cysts were identified within the affected cerebral parenchyma and confirmed by indirect immunofluorescence assay and real-time PCR as Balamuthia mandrillaris. B. mandrillaris is found in soil and water and the infection has been reported in both immunocompromised and immunocompetent humans and rarely in the dog.

An Acute Case of Granulomatous Amoebic Encephalitis-Balamuthia mandrillaris Infection

A 74-year-old woman who exhibited drowsiness was referred to our hospital. Enhanced head magnetic resonance imaging (MRI) revealed multiple ring-enhancing lesions and lesions showing partial mild hemorrhaging. The patient gradually progressed to a comatose condition with notable brain deterioration of unknown cause on follow-up MRI. On day nine, the patient inexplicably died, although brain herniation was suspected. Autopsy and histopathology revealed numerous amoebic trophozoites in the perivascular spaces and within the necrotic tissue. Brain immunostaining tested positive for Balamuthia mandrillaris. Infection due to free-living amoeba is rare in Japan; however, it may increase in the near future due to unknown reasons.

Cutaneous Balamuthia mandrillaris infection as a precursor to Balamuthia amoebic encephalitis (BAE) in a healthy 84-year-old Californian

Soil and freshwater-dwelling amoebae may opportunistically infect the skin and evoke a granulomatous dermatitis that camouflages their underlying morphology. Amoebic infestations are incredibly rare in the U.S., predominantly occurring in the young, elderly, and immunocompromised. Sadly, because diagnosis is difficult and unsuspected, most cases are diagnosed at autopsy. The following case is of a healthy 84-year-old man with a non-healing nodulo-ulcerative cutaneous lesion on his left forearm that appeared following a gardening injury. Lesional punch biopsies repeatedly showed non-specific granulomatous inflammation with no pathogens evident histologically or by culture. Histopathologic diagnosis was made five months after initial presentation via identification of amoebic trophozoite forms in tissue from a large excisional specimen. Anti-amoebic therapy was initiated immediately. The patient experienced mental status changes three days following lesion excision, with evidence of a cystic mass in the left medial parieto-occipital lobe by CT. Both intraoperative brain biopsies and cutaneous tissue samples tested positive for Balamuthia mandrillaris by indirect immunofluorescent antibody assay performed at the Centers for Disease Control. The patient achieved a full recovery on a triple antibiotic regimen. Clinical suspicion and thorough histopathologic analysis may determine the difference between survival and death for a patient presenting with a treatment-refractory localized granulomatous lesion.

Amoebic meningoencephalitis and disseminated infection caused by Balamuthia mandrillaris in a Western lowland gorilla (Gorilla gorilla gorilla)

CASE DESCRIPTION A 22-year-old male gorilla (Gorilla gorilla gorilla) housed in a zoo was evaluated for signs of lethargy, head-holding, and cervical stiffness followed by development of neurologic abnormalities including signs of depression, lip droop, and tremors. CLINICAL FINDINGS Physical examination under general anesthesia revealed a tooth root abscess and suboptimal body condition. A CBC and serum biochemical analysis revealed mild anemia, neutrophilia and eosinopenia consistent with a stress leukogram, and signs consistent with dehydration. Subsequent CSF analysis revealed lymphocytic pleocytosis and markedly increased total protein concentration. TREATMENT AND OUTCOME Despite treatment with antimicrobials, steroids, and additional supportive care measures, the gorilla's condition progressed to an obtunded mentation with grand mal seizures over the course of 10 days. Therefore, the animal was euthanized and necropsy was performed. Multifocal areas of malacia and hemorrhage were scattered throughout the brain; on histologic examination, these areas consisted of necrosis and hemorrhage associated with mixed inflammation, vascular necrosis, and intralesional amoebic trophozoites. Tan foci were also present in the kidneys and pancreas. Immunohistochemical testing positively labeled free-living amoebae within the brain, kidneys, eyes, pancreas, heart, and pulmonary capillaries. Subsequent PCR assay of CSF and frozen kidney samples identified the organism as Balamuthia mandrillaris, confirming a diagnosis of amoebic meningoencephalitis. CLINICAL RELEVANCE Infection with B mandrillaris has been reported to account for 2.8% of captive gorilla deaths in North America over the past 19 years. Clinicians working with gorillas should have a high index of suspicion for this diagnosis when evaluating and treating animals with signs of centrally localized neurologic disease.

Isolation of Balamuthia mandrillaris from soil samples in North-Western Iran

Balamuthia mandrillaris is an opportunistic free-living amoebae (FLA) which has been reported as the causative agent of the fatal Balamuthia amoebic encephalitis (BAE). Currently, the transmission dynamics of this pathogen remain poorly understood although the organism has been associated with soils, and thus, soil exposure has been identified as a risk factor for this pathogenic amoeba. Nevertheless, environmental isolation of B. mandrillaris is a rare event and strains of this amoebic species have been isolated from soil and dust sources only in seven previous reports (Iran, Mexico, USA, Peru, Costa Rica, Guinea Bissau, and Jamaica). In Iran, a previous study reported the isolation of B. mandrillaris from dust collected in the city of Tehran and free of known infectious involvement. Therefore, in this work, 55 soil samples collected from public and recreational areas of East Azerbaijan, North-Western Iran, were investigated for the presence of this pathogen. Samples were cultured in 2% non-nutrient agar plates and were monitored 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 ribosomal DNA (rDNA) of B. mandrillaris. The obtained results revealed the presence of this emerging pathogen in 5 of 55 samples included in the study. Homology analysis of the obtained DNA sequences revealed high similarity with previously isolated strains from clinical and environmental sources. To the best of our knowledge, this is the first report on the isolation of B. mandrillaris from soil sources in Iran related to human activity and the second time that this pathogen is isolated from the environment in this country.

Presence of Balamuthia mandrillaris in hot springs from Mazandaran province, northern Iran

Balamuthia mandrillaris is an opportunistic free-living amoeba that has been reported to cause cutaneous lesions and Balamuthia amoebic encephalitis. The biology and environmental distribution of B. mandrillaris is still poorly understood and isolation of this pathogen from the environment is a rare event. Previous studies have reported that the presence of B. mandrillaris in the environment in Iran may be common. However, no clinical cases have been reported so far in this country. In the present study, a survey was conducted in order to evaluate the presence of B. mandrillaris in hot-spring samples of northern Iran. A total of 66 water samples were analysed using morphological and molecular tools. Positive samples by microscopy were confirmed by performing PCR amplification of the 16S rRNA gene of B. mandrillaris. Sequencing of the positive amplicons was also performed to confirm morphological data. Two of the 66 collected water samples were positive for B. mandrillaris after morphological and molecular identification. Interestingly, both positive hot springs had low pH values and temperatures ranging from 32 °C to 42 °C. Many locals and tourists use both hot springs due to their medicinal properties and thus contact with water bodies containing the organism increases the likelihood of infection. To the best of our knowledge, this is the first report on the isolation of B. mandrillaris from hot-spring sources related to human activity. Therefore, B. mandrillaris should be considered as a possible causative agent if cases of encephalitis are suspected following immersion in hot springs in addition to Acanthamoeba and Naegleria.

Presence of potentially pathogenic free-living amoebae strains from well water samples in Guinea-Bissau

Free-living amoebae (FLA) include opportunistic pathogens such as Naegleria fowleri, Balamuthia mandrillaris, and the genera Sappinia and Acanthamoeba. In this study, a survey was conducted in order to evaluate the presence of potentially pathogenic amoebic strains in water samples collected from wells located in the western part of Guinea-Bissau. The samples were left to precipitate for 48 hours and then the sediments were seeded on non-nutrient agar plates containing Escherichia coli spread and cultures were checked daily for the presence of FLA. Identification of FLA strains was based on the morphological and polymerase chain reaction (PCR) using the 18S rDNA or 16S mitochondrial rDNA genes in the case of Naegleria and Balamuthia genera, respectively. In the case of positive samples of Acanthamoeba, strains were further classified at the genotype level by sequencing the diagnostic fragment 3 (DF3) region located in the 18S rDNA gene as previously described. Sappinia sp. was not isolated during the study and thus, no molecular analysis was performed for this genus. The obtained results revealed the presence of Acanthamoeba (genotypes T3 and T4), Naegleria fowleri, and Balamuthia mandrillaris. To the best of our knowledge, this is the first report demonstrating the presence of FLA in water bodies from Guinea-Bissau and the first report on the isolation of Balamuthia mandrillaris from environmental sources in Africa.

Balamuthia mandrillaris meningoencephalitis associated with solid organ transplantation--review of cases

We report the first identified transmission of Balamuthia mandrillaris through solid organ transplantation. Kidneys were transplanted from a donor with presumptive diagnosis of autoimmune encephalitis. Shortly after, the recipients developed neurologic symptoms. Magnetic Resonance Imaging of the brain from the donor and both kidney recipients demonstrated multiple ring enhancing lesions with surrounding edema and adjacent leptomeningeal extension. In addition most of the lesions demonstrated signal changes suggesting central hemorrhagic foci. Specimens were tested locally and at the Centers for Disease Control and Prevention. Histopathology revealed B. mandrillaris in either brain tissue and/or cerebral spinal fluid in the donor and recipients.

Status of free-living amoebae (Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris) in drinking water supplies in Karachi, Pakistan

The ability of pathogenic free-living amoebae to produce infections is a growing concern. In this study, we investigated the presence of free-living amoebae (Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris) in drinking water supplies in Karachi, Pakistan. Fifty-two domestic tap water samples were examined. Amoebae were identified by morphological characteristics and polymerase chain reaction. Thirty percent of the examined samples were positive for Acanthamoeba spp., 8% for N. fowleri while B. mandrillaris were not recovered. Additionally we examined secretory IgA antibody to Acanthamoeba and B. mandrillaris. Acanthamoeba antibody prevalence rate was 100% in both males and females, while B. mandrillaris antibody prevalence rate was 5.5% in males only (females were negative). Our findings suggest that free-living amoebae are a potential health hazard in domestic water supplies in Karachi, Pakistan.

Successful treatment of granulomatous amoebic encephalitis with combination antimicrobial therapy

Granulomatous amoebic encephalitis (GAE) is a rare but fatal infection. Due to its nonspecific symptoms and laboratory and neuroradiological findings, it is rarely diagnosed antemortem. We herein present the case of a 72-year-old Japanese woman who was diagnosed with GAE following the detection of a pathogen similar to Balamuthia mandrillaris under a microscopic examination of cerebrospinal fluid sediment and who achieved remission with combination antimicrobial therapy. There are no previous reports of pathogens similar to B. mandrillaris being detected in cerebrospinal fluid antemortem; therefore, this case may be used as a benchmark for further studies.

Granulomatous amoebic encephalitis caused by Balamuthia mandrillaris in an immunocompetent girl

BACKGROUND

Balamuthia mandrillaris is a recently recognized cause of a rare, devastating infection, granulomatous amoebic encephalitis (GAE). Presenting symptoms of GAE are nonspecific and can last for months before becoming clinically significant. Once the infection involves the central nervous system, death often results within days to weeks. A high degree of clinical suspicion is needed to correctly diagnose this infection because definitive diagnostic tests are presently limited, and even then there are only sparse data concerning effective treatment. The importance of early diagnosis is emphasized because delay likely contributes to the extremely high mortality with this infection.

METHODS

This study presents a previously healthy, immunocompetent 2-year-old female patient who succumbed to GAE secondary to B. mandrillaris, with the intention of raising awareness of this devastating infection.

RESULTS

Balamuthia amoebic encephalitis is a devastating form of amoebic encephalitis that is increasingly reported in the literature.

CONCLUSIONS

GAE should be considered for a patient with atypical encephalitis and single or multiple lesions with surrounding edema evident on neurodiagnostic imaging.