Histopathologic spectrum and immunohistochemical diagnosis of amebic meningoencephalitis

Infectious Disease Pathology Branch, National Center for Infectious Diseases, Centers for Disease Control and Prevention, 1405 Clifton Road NE, Atlanta, GA 30322, USA.
Modern Pathology (Impact Factor: 6.19). 01/2008; 20(12):1230-7. DOI: 10.1038/modpathol.3800973
Source: PubMed


Traditionally, Naegleria fowleri infections are labeled primary amebic meningoencephalitis because of prominent meningeal neutrophilic inflammation. Acanthamoeba spp. and Balamuthia mandrillaris are labeled granulomatous amebic encephalitis because of parenchymal granulomatous inflammation. We compared histopathologic and immunohistochemical features of 18 cases with central nervous system free-living ameba infections. Immunohistochemical assays using polyclonal antibodies that reacted specifically against each genus identified 11 patients with Balamuthia infection, four with N. fowleri, and three with Acanthamoeba. Immunohistochemical assays highlighted the presence of trophozoites that were difficult to identify with hematoxylin and eosin stains in areas of necrosis or where macrophages were abundant. Immunohistochemical assays also demonstrated the presence of granular antigens inside macrophages and blood vessel walls. Amebic cysts were observed in three patients with Acanthamoeba infection and in three with Balamuthia. Patients with Acanthamoeba infection showed granulomatous inflammation. Patients with Naegleria infection had neutrophilic inflammation. Balamuthia infections showed a spectrum of inflammation that ranged from primarily neutrophils to granulomas. Meningitis was present in 88% of cases. Immunohistochemical assays were useful to demonstrate the presence of granular antigens and confirmed the genus of the ameba. The spectrum of inflammation in cases of Balamuthia meningoencephalitis is broader than previously described. The term amebic meningoencephalitis describes better the histopathologic findings than the currently used classification of primary amebic meningoencephalitis and granulomatous amebic encephalitis.

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Available from: Govinda Visvesvara, Feb 06, 2015
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    • "Moreover, GAE caused by Acanthamoeba spp. or B. mandrillaris are similar in terms of clinical course, neuroimaging, and pathological findings. Therefore, the diagnosis must be confirmed with indirect immunofluorescence (IIF) techniques, immunohistochemistry (IHC), or PCR [27,28]. Since IIF and IHC techniques for these amebas are readily available in only few specialized centers such as the Centers for Disease Control and Prevention (CDC; Atlanta, Georgia, USA), PCR technique, as performed on our patient, may be a more easily accessible tool leading to an earlier diagnosis and treatment of BAE before mortality. "
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    ABSTRACT: Balamuthia mandrillaris is one of the 4 amebas in fresh water and soil that cause diseases in humans. Granulomatous amebic encephalitis (GAE), caused by B. mandrillaris, is a rare but life-threatening condition. A 4-year-old, previously healthy, Thai girl presented with progressive headache and ataxia for over a month. Neuroimaging studies showed an infiltrative mass at the right cerebellar hemisphere mimicking a malignant cerebellar tumor. The pathological finding after total mass removal revealed severe necrotizing inflammation, with presence of scattered amebic trophozoites. Cerebrospinal fluid (CSF) obtained from lumbar puncture showed evidence of non-specific inflammation without identifiable organisms. A combination of pentamidine, sulfasalazine, fluconazole, and clarithromycin had been initiated promptly before PCR confirmed the diagnosis of Balamuthia amebic encephalitis (BAE). The patient showed initial improvement after the surgery and combined medical treatment, but gradually deteriorated and died of multiple organ failure within 46 days upon admission despite early diagnosis and treatment. In addition to the case, 10 survivors of BAE reported in the PubMed database were briefly reviewed in an attempt to identify the possible factors leading to survival of the patients diagnosed with this rare disease.
    Full-text · Article · Jun 2013 · The Korean Journal of Parasitology
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    • "ich , cysts appear red whereas tissues appear black in color ( Marciano - Cabral & Cabral , 2003 ) . Other specialized techniques employed to demonstrate the presence of amoeba are transmission electron microscopy and immunofluorescent or immunoperoxidase staining ( Willaert & Stevens , 1976 , Stevens , et al . , 1977 , McKellar , et al . , 2006 , Guarner , et al . , 2007 ) . However , because most Acanthamoeba spp . are antigenically related , the use of immunohistochemical techniques does not permit identification by species . To identify structural brain lesions , computed tomography and magnetic resonance imaging are widely used ( Sell , et al . , 1997 , Kidney & Kim , 1998 ) . These evaluations can "

    Full-text · Chapter · Nov 2011
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    ABSTRACT: Il a été bien documenté que les différentes canalisations des unités de soins dentaires contiennent un épais biofilm. Ce biofilm est constitué entre autres de bactéries, mais aussi d’amibes. Certaines amibes ont un potentiel pathogène et peuvent causer des infections graves. Deux cas d’infections amibiennes et possiblement reliées aux unités dentaires ont retenu notre attention et sont à l’origine du présent projet. L’identification morphologique des amibes afin de déterminer si elles présentent un potentiel pathogène ou non est une tâche ardue, même pour les protozoologistes chevronnés. Nous avons donc utilisé la réaction de polymérase en chaîne (PCR) pour identifier les amibes. Des nouvelles amorces ont été élaborées pour détecter les amibes des genres Acanthamoeba ainsi que Naegleria. Des échantillons d’eau et de terre ont été prélevés dans l’environnement, et des échantillons d’eau et de biofilm ont été prélevés dans les unités dentaires. Une partie de chaque échantillon a été mise en culture selon une méthode améliorée pour une identification morphologique, et l’autre partie a été soumise à un PCR direct. Des Acanthamoebae et/ou des Naegleriae ont été détectées dans 100% des échantillons, mais les espèces varient d’un échantillon à l’autre. Des amibes à potentiel pathogènes sont détectables dans les unités dentaires ainsi que dans l’environnement, et celles-ci pourraient représenter un risque pour la santé de certains individus. It has been well documented that the various tubing of a dental unit are covered with a thick biofilm. This biofilm mostly consists of bacteria, but amoebae can be found within the biofilm as well. Some amoebae are potential pathogens and may cause serious infections. Two cases of amoebic infections that were possibly linked with dental units drew our attention and stimulated our researches. Morphologic identification of amoebae in order to determine their possible pathogenicity requires much expertise, and is even difficult for proficient protozoologists. Therefore, the use of PCR is essential to detect potentially pathogenic amoebae with subjectivity. We elaborated new primers for the detection of Acanthamoeba spp. and Naegleria spp. Samples of water and dirt were taken in the environment, and samples of water and biofilm were taken in dental units. A part of each samples was cultivated for morphological identification, when a second part was utilized for PCR identification. Acanthamoebae and/or Naegleriae were detected in 100% of our samples, but the species varied from one sample to another. Potentially pathogenic amoebae were detected in dental units and in the environment, which could represent a health risk for some individuals.
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