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Journal ArticleDOI: 10.1080/17843286.2019.1660023

Granulomatous amoebic encephalitis caused by Acanthamoeba in a patient with AIDS: a challenging diagnosis.

04 Mar 2021-Acta Clinica Belgica (Acta Clinica Belgica)-Vol. 76, Iss: 2, pp 127-131
Abstract: Introduction: Acanthamoeba spp. is a ubiquitous free-living amoeba that causes human infections affecting predominantly the cornea and central nervous system. The diagnosis and treatment of Acantha...

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Journal ArticleDOI: 10.1016/J.EXPPARA.2019.107788
Sonali K. Kalra, Palvi Sharma, Kirti Shyam, Nidhi Tejan1  +1 moreInstitutions (1)
Abstract: 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.

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Topics: Acanthamoeba (53%)

28 Citations


Open accessJournal ArticleDOI: 10.3389/FMICB.2020.616213
Abstract: Ever since the publication of the seminal paper by Lynn Margulis in 1967 proposing the theory of the endosymbiotic origin of organelles, the study of the symbiotic relationships between unicellular eukaryotes and prokaryotes has received ever-growing attention by microbiologists and evolutionists alike. While the evolutionary significance of the endosymbiotic associations within protists has emerged and is intensively studied, the impact of these relationships on human health has been seldom taken into account. Microbial endosymbioses involving human eukaryotic pathogens are not common, and the sexually transmitted obligate parasite Trichomonas vaginalis and the free-living opportunistic pathogen Acanthamoeba represent two unique cases in this regard, to date. The reasons of this peculiarity for T. vaginalis and Acanthamoeba may be due to their lifestyles, characterized by bacteria-rich environments. However, this characteristic does not fully explain the reason why no bacterial endosymbiont has yet been detected in unicellular eukaryotic human pathogens other than in T. vaginalis and Acanthamoeba, albeit sparse and poorly investigated examples of morphological identification of bacteria-like microorganisms associated with Giardia and Entamoeba were reported in the past. In this review article we will present the body of experimental evidences revealing the profound effects of these examples of protist/bacteria symbiosis on the pathogenesis of the microbial species involved, and ultimately their impact on human health.

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Topics: Acanthamoeba (52%)

4 Citations


Open accessJournal Article
Abstract: Introduccion: Naegleria fowleri, Acanthamoeba spp. y Balamuthia mandrillaris son amebas de vida libre que producen danos sustanciales del sistema nervioso central y cuyo diagnostico premortem es poco frecuente. Objetivo: Proveer una vision general de los aspectos clinico-epidemiologicos y las posibilidades diagnosticas mas eficaces en la meningoencefalitis amebiana primaria y la encefalitis granulomatosa amebiana, asi como las experiencias de tratamiento expuestas en la literatura reciente. Metodos: Se realizo una revision bibliografica sobre las amebas de vida libre. Se analizo la informacion obtenida de articulos cientificos en la base de datos Google Scholar ®, PubMed y las citas relacionadas por el programa en PubMed Central. Analisis y sintesis de la informacion : En primer termino del analisis de la meningoencefalitis amebiana primaria y la encefalitis granulomatosa amebiana, resalta la diferenciacion de sus caracteristicas clinicas y epidemiologicas, tambien que el liquido cefalorraquideo presenta gran relevancia para el diagnostico de la meningoencefalitis amebiana primaria. Sin embargo, para los casos presuntivos de la encefalitis granulomatosa amebiana el examen del liquido cefalorraquideo depende de la valoracion riesgo-beneficio y se ha obtenido mayor positividad con el diagnostico histopatologico de biopsias premortem . En general, se acrecienta la implementacion de la investigacion del ADN por diferentes metodos que brindan certeza de cada una de las especies de AVL causantes de enfermedad neurologica. El aislamiento en cultivo confirmatorio de N. fowleri , Acanthamoeba spp. y B. mandrillaris presenta diferencias en la factibilidad de crecimiento en diversos medios de acuerdo con la especie y limitaciones adicionales. Conclusiones: La mortalidad asociada con las infecciones del sistema nervioso central por amebas de vida libre permanece alta, aunque varios estudios brindan experiencias utiles a partir de los casos de pacientes que han sobrevivido. Resulta importante tener en cuenta que el diagnostico rapido de la infeccion es clave para un tratamiento exitoso.

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3 Citations


Open accessJournal ArticleDOI: 10.2166/WH.2020.401
Abstract: The present study aimed to investigate an effective, sustainable and accessible way to inactivate chlorine-resistant microorganisms, such as Acanthamoeba castellanii, through the photolysis of sodium chloride (NaCl) and sodium hypochlorite (NaOCl) in the water matrix. The trophozoites and cysts (2 × 10 per 8 mL) were exposed for 30, 60, 90, 120 and 150 min to the photolysis effect of NaOCl (1.0, 2.0, 4.0 and 8.0 mg/L) or NaCl (5.0, 10, 20 and 40 g/L) by ultraviolet light C (243 μW·cm), then the viability was analyzed. The inactivation of all trophozoites was achieved by exposure to the photolysis effect of 2.0 mg/L of NaOCl or 20 g/L of NaCl, in 150 or 120 min, respectively. Inactivation of all cysts was achieved by double exposure to the photolysis effect of 1.0 mg/L NaOCl or 5.0 g/L NaCl from 90 min of each exposure round. The exposure time was a strong determinant in the inactivation of A. castellanii trophozoites or cysts. The photolysis of NaOCl or NaCl is an effective method to eliminate A. castellanii in water. These findings expand the list of chlorine-resistant microorganisms that can be inactivated by NaOCl photolysis and show that NaCl photolysis is a new and promising method for treating swimming pool water and wastewater.

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Topics: Acanthamoeba castellanii (65%), Sodium hypochlorite (64%), Ultraviolet light (61%) ... read more

3 Citations


Open accessJournal ArticleDOI: 10.3390/PHARMACEUTICS13030343
05 Mar 2021-Pharmaceutics
Abstract: Despite advances in medical knowledge, parasitic diseases remain a significant global health burden and their pharmacological treatment is often hampered by drug toxicity. Therefore, drug delivery systems may provide useful advantages when used in combination with conventional therapeutic compounds. Dendrimers are three-dimensional polymeric structures, characterized by a central core, branches and terminal functional groups. These nanostructures are known for their defined structure, great water solubility, biocompatibility and high encapsulation ability against a wide range of molecules. Furthermore, the high ratio between terminal groups and molecular volume render them a hopeful vector for drug delivery. These nanostructures offer several advantages compared to conventional drugs for the treatment of parasitic infection. Dendrimers deliver drugs to target sites with reduced dosage, solving side effects that occur with accepted marketed drugs. In recent years, extensive progress has been made towards the use of dendrimers for therapeutic, prophylactic and diagnostic purposes for the management of parasitic infections. The present review highlights the potential of several dendrimers in the management of parasitic diseases.

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2 Citations


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14 results found


Open accessJournal ArticleDOI: 10.1128/CMR.16.2.273-307.2003
Abstract: Acanthamoeba spp. are free-living amebae that inhabit a variety of air, soil, and water environments. However, these amebae can also act as opportunistic as well as nonopportunistic pathogens. They are the causative agents of granulomatous amebic encephalitis and amebic keratitis and have been associated with cutaneous lesions and sinusitis. Immuno compromised individuals, including AIDS patients, are particularly susceptible to infections with Acanthamoeba. The immune defense mechanisms that operate against Acanthamoeba have not been well characterized, but it has been proposed that both innate and acquired immunity play a role. The ameba's life cycle includes an active feeding trophozoite stage and a dormant cyst stage. Trophozoites feed on bacteria, yeast, and algae. However, both trophozoites and cysts can retain viable bacteria and may serve as reservoirs for bacteria with human pathogenic potential. Diagnosis of infection includes direct microscopy of wet mounts of cerebrospinal fluid or stained smears of cerebrospinal fluid sediment, light or electron microscopy of tissues, in vitro cultivation of Acanthamoeba, and histological assessment of frozen or paraffin-embedded sections of brain or cutaneous lesion biopsy material. Immunocytochemistry, chemifluorescent dye staining, PCR, and analysis of DNA sequence variation also have been employed for laboratory diagnosis. Treatment of Acanthamoeba infections has met with mixed results. However, chlorhexidine gluconate, alone or in combination with propamidene isethionate, is effective in some patients. Furthermore, effective treatment is complicated since patients may present with underlying disease and Acanthamoeba infection may not be recognized. Since an increase in the number of cases of Acanthamoeba infections has occurred worldwide, these protozoa have become increasingly important as agents of human disease.

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Topics: Acanthamoeba infection (77%), Acanthamoeba (68%), Acanthamoeba castellanii (65%) ... read more

1,067 Citations


Open accessJournal ArticleDOI: 10.1128/JCM.00875-06
Abstract: 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.

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Topics: Balamuthia mandrillaris (60%), Naegleria fowleri (53%), Multiplex (52%) ... read more

303 Citations


Journal ArticleDOI: 10.1111/J.1550-7408.2005.00082.X
Abstract: The anticancer agent miltefosine and the antifungal drug voriconazole were tested in vitro against Balamuthia mandrillaris, Acanthamoeba spp., and Naegleria fowleri. All three amebas are etiologic agents of chronic (Balamuthia, Acanthamoeba) or fulminant (Naegleria) encephalitides in humans and animals and, in the case of Acanthamoeba, amebic keratitis. Balamuthia exposed to or=40 microM were generally amebacidal, with variation in sensitivity between strains. At amebastatic drug concentrations, recovery from drug effects could take as long as 2 weeks. Acanthamoeba spp. recovered from exposure to 40 microM, but not 80 microM miltefosin. Attempts to define more narrowly the minimal inhibitory (MIC) and minimal amebacidal concentrations (MAC) for Balamuthia and Acanthamoeba were difficult due to persistence of non-proliferating trophic amebas in the medium. For N. fowleri, 40 and 55 microM were the MIC and MAC, respectively, with no trophic amebas seen at the MAC. Voriconazole had little or no inhibitory effect on Balamuthia at concentrations up to 40 microg/ml, but had a strong inhibitory effect upon Acanthamoeba spp. and N. fowleri at all drug concentrations through 40 microg/ml. Following transfer to drug-free medium, Acanthamoeba polyphaga recovered within a period of 2 weeks; N. fowleri amebas recovered from exposure to 1 microg/ml, but not from higher concentrations. All testing was done on trophic amebas; drug sensitivities of cysts were not examined. Miltefosine and voriconazole are potentially useful drugs for treatment of free-living amebic infections, though sensitivities differ between genera, species, and strains.

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Topics: Balamuthia mandrillaris (64%), Balamuthia (58%), Acanthamoeba (57%) ... read more

157 Citations


Open accessJournal Article
Abstract: Primary amebic meningoencephalitis and granulomatous amebic meningoencephalitis are central nervous system infections caused by free-living amebae. We describe the neuroimaging findings in 5 such cases on CT and MR imaging. A spectrum of findings was seen in the form of multifocal parenchymal lesions, pseudotumoral lesions, meningeal exudates, hemorrhagic infarcts, and necrosis in the brain. Familiarity with the imaging findings is important for the diagnosis and management of this nearly universally fatal disease.

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Topics: Meningoencephalitis (57%)

64 Citations


Open accessJournal Article
Abstract: Infections caused by free-living amebae (FLA) are severe and life-threatening. These infections include primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri and granulomatous amebic encephalitis caused by Balamuthia mandrillaris and Acanthamoeba species. Although several drugs have in vitro activity against FLA, mortality from these infections remains>90% despite treatment with combinations of drugs.

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63 Citations


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