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.

On the diversity and clinical importance of Acanthamoeba spp. from Group 1.

Group 1 acanthamoebae are morphologically and phylogenetically distinct from all other Acanthamoeba species. They include five species, each labelled by its genotype: A. astronyxis (T7), A. tubiashi (T8), A. comandoni (T9), unnamed Acanthamoeba sp. (T17), and A. byersi (T18). Thought only environmental, they have recently attracted attention due to their recovery in cases of human keratitis and encephalitis, the main diseases caused by Acanthamoeba, where the usual causative agents are mainly species of Groups 2 and 3. Analysis of the available data confirms the pathogenic importance of these species, although it is probably minor compared to that of the species in Groups 2 and 3. In addition, it should be noted that there are difficulties in identifying genotypes by widely used molecular methods, and some misidentifications are revealed.

Development of a risk scoring system for prognostication in HIV-related toxoplasma encephalitis.

BACKGROUND: This study aims to evaluate specific risk factors influencing prognosis of HIV-infected patients with toxoplasma encephalitis (TE) in order to develop a prognostic risk scoring system for them. METHODS: This is a six-center retrospective study of hospitalized HIV/TE patients. Data including six-week mortality after diagnosis, baseline characteristics, clinical features, laboratory tests and radiological characteristics of eligible patients were assimilated for risk model establishing. RESULTS: In this study, the six-week mortality among 94 retrospective cases was 11.7% (11/94). Seven specific risk factors, viz. time from symptom onset to presentation, fever, dizziness, CD4+ T-cell counts, memory deficits, patchy brain lesions, and disorders of consciousness were calculated to be statistically associated with mortality. A criterion value of '9' was selected as the optimal cut-off value of the established model. The AUC of the ROC curve of this scoring model was 0.976 (p < 0.001). The sensitivity and specificity of the risk scoring model was 100.0 and 86.9%, respectively, which were 81.8 and 94.1% of this scoring model in the verification cohort, respectively. CONCLUSIONS: The developed scoring system was established with simple risk factors, which also allows expeditious implementation of accurate prognostication, and appropriate therapeutic interventions in HIV-infected patients with TE.

Nanoparticles based therapeutic efficacy against Acanthamoeba: Updates and future prospect.

Acanthamoeba sp. is a free living amoeba that causes severe, painful and fatal infections, viz. Acanthamoeba keratitis and granulomatous amoebic encephalitis among humans. Antimicrobial chemotherapy used against Acanthamoeba is toxic to human cells and show side effects as well. Infections due to Acanthamoeba also pose challenges towards currently used antimicrobial treatment including resistance and transformation of trophozoites to resistant cyst forms that can lead to recurrence of infection. Therapeutic agents targeting central nervous system infections caused by Acanthamoeba should be able to cross blood-brain barrier. Nanoparticles based drug delivery put forth an effective therapeutic method to overcome the limitations of currently used antimicrobial chemotherapy. In recent years, various researchers investigated the effectiveness of nanoparticles conjugated drug and/or naturally occurring plant compounds against both trophozoites and cyst form of Acanthamoeba. In the current review, a reasonable effort has been made to provide a comprehensive overview of various nanoparticles tested for their efficacy against Acanthamoeba. This review summarizes the noteworthy details of research performed to elucidate the effect of nanoparticles conjugated drugs against Acanthamoeba.

Metformin-coated silver nanoparticles exhibit anti-acanthamoebic activities against both trophozoite and cyst stages.

Acanthamoeba castellanii is an opportunistic protozoan responsible for serious human infections including Acanthamoeba keratitis and granulomatous amoebic encephalitis. Despite advances in antimicrobial therapy and supportive care, infections due to Acanthamoeba are a major public concern. Current methods of treatment are not fully effective against both the trophozoite and cyst forms of A. castellanii and are often associated with severe adverse effects, host cell cytotoxicity and recurrence of infection. Therefore, there is an urgent need to develop new therapeutic approaches for the treatment and management of Acanthamoebic infections. Repurposing of clinically approved drugs is a viable avenue for exploration and is particularly useful for neglected and rare diseases where there is limited interest by pharmaceutical companies. Nanotechnology-based drug delivery systems offer promising approaches in the biomedical field, particularly in diagnosis and drug delivery. Herein, we conjugated an antihyperglycemic drug, metformin with silver nanoparticles and assessed its anti-acanthamoebic properties. Characterization by ultraviolet-visible spectrophotometry and atomic force microscopy showed successful formation of metformin-coated silver nanoparticles. Amoebicidal and amoebistatic assays revealed that metformin-coated silver nanoparticles reduced the viability and inhibited the growth of A. castellanii significantly more than metformin and silver nanoparticles alone at both 5 and 10 µM after 24 h incubation. Metformin-coated silver nanoparticles also blocked encystation and inhibited the excystation in Acanthamoeba after 72 h incubation. Overall, the conjugation of metformin with silver nanoparticles was found to enhance its antiamoebic effects against A. castellanii. Furthermore, the pretreatment of A. castellanii with metformin and metformin-coated silver nanoparticles for 2 h also reduced the amoebae-mediated host cell cytotoxicity after 24 h incubation from 73% to 10% at 10 µM, indicating that the drug-conjugated silver nanoparticles confer protection to human cells. These findings suggest that metformin-coated silver nanoparticles hold promise in the improved treatment and management of Acanthamoeba infections.

Acanthamoeba spp. and Balamuthia mandrillaris leading to fatal granulomatous amebic encephalitis.

Acanthamoeba spp. and Balamuthia mandrillaris are free-living amebae known to cause disseminated and fatal central nervous system dysfunction which manifests as granulomatous amebic encephalitis (GAE) with exceedingly rare frequency. We report two lethal cases of infection with free-living amebae: an acute case of Acanthamoeba spp. infection in an immunocompromised female and a subacute case of B. mandrillaris in a Hispanic male. The Acanthamoeba spp. infection presented with an atypical lesion in the thalamus that caused rapid deterioration of the patient while the case of B. mandrillaris had a prolonged clinical course with multifocal lesions beginning in the frontal lobe. Cerebrospinal fluid results were non-specific in both cases, however, post-mortem histology demonstrated the presence of trophozoites along a perivascular distribution of necrosis and infiltrate composed primarily of neutrophils. In addition to detailing the clinical presentations of these infrequent amebic infections, we offer insight into the difficulties surrounding their diagnoses in order to aid the clinician in accurate and timely identification.

Acanthamoeba and its pathogenic role in granulomatous amebic encephalitis.

Acanthamoeba is a free-living amoeba that is widely distributed in the environment. It is an opportunist protist, which is known to cause rare yet fatal infection of the central nervous system (CNS), granulomatous amebic encephalitis (GAE) in humans. GAE cases are increasingly been reported among immunocompromised patients, with few cases in immunocompetent hosts. Diagnosis of GAE primarily includes neuroimaging, microscopy, cerebrospinal fluid (CSF) culture, histopathology, serology and molecular techniques. Early diagnosis is vital for proper management of infected patients. Combination therapeutic approach has been tried in various GAE cases reported worldwide. We tried to present a comprehensive review, which summarizes on the epidemiology of GAE caused by Acanthamoeba along with the associated clinical symptoms, risk factors, diagnosis and treatment of GAE among infected patients.

Balamuthia mandrillaris-Related Primary Amoebic Encephalitis in China Diagnosed by Next Generation Sequencing and a Review of the Literature.

BACKGROUND: Encephalitis is caused by infection, immune mediated diseases, or primary inflammatory diseases. Of all the causative infectious pathogens, 90% are viruses or bacteria. Granulomatous amoebic encephalitis (GAE), caused by Balamuthia mandrillaris, is a rare but life-threatening disease. Diagnosis and therapy are frequently delayed due to the lack of specific clinical manifestations. METHOD: A healthy 2 year old Chinese male patient initially presented with a nearly 2 month history of irregular fever. We present this case of granulomatous amoebic encephalitis caused by B. mandrillaris. Next generation sequencing of the patient's cerebrospinal fluid (CSF) was performed to identify an infectious agent. RESULT: The results of next generation sequencing of the CSF showed that most of the mapped reads belonged to Balamuthia mandrillaris. CONCLUSION: Next generation sequencing (NGS) is an unbiased and rapid diagnostic tool. The NGS method can be used for the rapid identification of causative pathogens. The NGS method should be widely applied in clinical practice and help clinicians provide direction for the diagnosis of diseases, especially for rare and difficult cases.

Diagnosis of Chagasic Encephalitis by Sequencing of 28S rRNA Gene.

We report a case of chagasic encephalitis diagnosed by 28S rRNA sequencing. The diagnosis of chagasic encephalitis is challenging, given the broad differential diagnosis for central nervous system lesions in immunocompromised patients and low sensitivity of traditional diagnostics. Sequencing should be part of the diagnostic armamentarium for potential chagasic encephalitis.

Innovative Methodology in the Discovery of Novel Drug Targets in the Free-Living Amoebae.

Despite advances in drug discovery and modifications in the chemotherapeutic regimens, human infections caused by free-living amoebae (FLA) have high mortality rates (~95%). The FLA that cause fatal human cerebral infections include Naegleria fowleri, Balamuthia mandrillaris and Acanthamoeba spp. Novel drug-target discovery remains the only viable option to tackle these central nervous system (CNS) infection in order to lower the mortality rates caused by the FLA. Of these FLA, N. fowleri causes primary amoebic meningoencephalitis (PAM), while the A. castellanii and B. Mandrillaris are known to cause granulomatous amoebic encephalitis (GAE). The infections caused by the FLA have been treated with drugs like Rifampin, Fluconazole, Amphotericin-B and Miltefosine. Miltefosine is an anti-leishmanial agent and an experimental anti-cancer drug. With only rare incidences of success, these drugs have remained unsuccessful to lower the mortality rates of the cerebral infection caused by FLA. Recently, with the help of bioinformatic computational tools and the discovered genomic data of the FLA, discovery of newer drug targets has become possible. These cellular targets are proteins that are either unique to the FLA or shared between the humans and these unicellular eukaryotes. The latter group of proteins has shown to be targets of some FDA approved drugs prescribed in non-infectious diseases. This review out-lines the bioinformatics methodologies that can be used in the discovery of such novel drug-targets, their chronicle by in-vitro assays done in the past and the translational value of such target discoveries in human diseases caused by FLA.

Rickettsia typhi as Cause of Fatal Encephalitic Typhus in Hospitalized Patients, Hamburg, Germany, 1940-1944.

We evaluated formalin-fixed paraffin-embedded tissue specimens from 7 patients who died with encephalitic typhus in Hamburg, Germany, during World War II. The archived specimens included only central nervous system tissues >70 years old that had been stored at room temperature. We demonstrated successful detection of Rickettsia typhi DNA by a nested qPCR specific to prsA in 2 patients. These results indicate that R. typhi infections contributed to typhus outbreaks during World War II. Immunohistochemical analyses of brain tissue specimens of R. typhi DNA-positive and -negative specimens showed perivascular B-cell accumulation. Around blood vessels, nodular cell accumulations consisted of CD4-positive and CD8-positive T cells and CD68-positive microglia and macrophages; neutrophils were found rarely. These findings are similar to those of previously reported R. prowazekii tissue specimen testing. Because R. typhi and R. prowazekii infections can be clinically and histopathologically similar, molecular analyses should be performed to distinguish the 2 pathogens.

Tannic acid-modified silver nanoparticles as a novel therapeutic agent against Acanthamoeba.

Free-living amoebae belonging to Acanthamoeba genus are widely distributed protozoans which are able to cause infection in humans and other animals such as keratitis and encephalitis. Acanthamoeba keratitis is a vision-threatening corneal infection with currently no available fully effective treatment. Moreover, the available therapeutic options are insufficient and are very toxic to the eye. Therefore, there is an urgent need for the development of more effective anti-amoebic agents. Nanotechnology approaches have been recently reported to be useful for the elucidation antimicrobial, antiviral, antifungal and antiprotozoal activities and thus, they could be a good approach for the development of anti-Acanthamoeba agents. Therefore, this study was aimed to explore the activity and cytotoxicity of tannic acid-modified silver nanoparticles, pure silver nanoparticles and pure gold nanoparticles against clinical strains of Acanthamoeba spp. The obtained results showed a significant anti-amoebic effect of the tannic acid-modified silver nanoparticles which also presented low cytotoxicity. Moreover, tannic acid-modified silver nanoparticles were well absorbed by the trophozoites and did not induce encystation. On the other hand, pure silver nanoparticles were only slightly active against the trophozoite stage and pure gold nanoparticles did not show any activity. In conclusion and based on the observed results, silver nanoparticle conjugation with tannic acid may be considered as potential agent against Acanthamoeba spp.

Lethal outcome of granulomatous acanthamoebic encephalitis in a man who was human immunodeficiency virus-positive: a case report.

BACKGROUND: Acanthamoeba species can cause disseminating infections in immunocompromised individuals. CASE PRESENTATION: Here, we report a case of granulomatous acanthamoebic encephalitis with a lethal outcome in a 54-year-old German man who was human immunodeficiency virus-positive. The diagnosis was based on symptoms of progressive neurological deficits, including sensorimotor paralysis of his right leg and deteriorating alertness. Due to the rapid course and rather late diagnosis of the infection, effective treatment could not be applied and he died 12 days after hospital admission. CONCLUSIONS: To the best of our knowledge, this is the second case of granulomatous acanthamoebic encephalitis reported within Germany. Our case highlights the importance of early diagnosis of granulomatous acanthamoebic encephalitis to prevent fatal outcome.

Balamuthia mandrillaris Granulomatous Amebic Encephalitis With Renal Dissemination in a Previously Healthy Child: Case Report and Review of the Pediatric Literature.

Balamuthia mandrillaris is a recently described ameba known to cause a subacute to chronic central nervous system infection called granulomatous amebic encephalitis. Evidence suggests that apparently immunocompetent persons are at risk for disease and show a similar nonspecific presentation to that of immunodeficient persons. However, evidence of hematogenous dissemination, which has been found in immunodeficient patients, has been lacking in immunocompetent patients. Here, we describe a previously healthy patient with B mandrillaris-associated granulomatous amebic encephalitis in whom both central nervous system and renal disease were found during autopsy, which suggests hematogenous dissemination. We also provide a comprehensive review of the pediatric literature on this disease and its clinical presentation in children.

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.