Encefalitis amebiana granulomatosa por Balamuthia mandrillaris en Chile confirmada con secuenciación de ADN / Granulomatous amoebic encephalitis due to Balamuthia mandrillaris in Chile confirmed with DNA sequencing

Las enfermedades causadas por amebas de vida libre son infecciones oportunistas que pueden tener un curso fatal. Pueden producir afecciones diseminadas graves con compromiso del sistema nervioso central, como la encefalitis amebiana granulomatosa. Esta infección es cada vez más frecuente en América Latina, aunque se reconocen tardíamente debido a la similitud con otras patologías o porque es inusual incluirla en el diagnóstico diferencial. Comunicamos un caso fatal de una encefalitis amebiana granulomatosa por Balamuthia mandrillaris en una niña de 10 años. Destacamos la gravedad de la afectación cerebral y la falta de esquemas antimicrobianos validados para su tratamiento. Hoy en el mundo esta infección es considerada una enfermedad emergente, influenciada por el cambio climático, lo que llama a estar atentos a su presencia.

Diseases caused by free-living amoebae are opportunistic infections that can have a fatal course. They can cause very serious disseminated conditions with involvement of the central nervous system such as granulomatous amoebic encephalitis. This infection has become more common in Latin America, although its recognition is late due to the similarity with other pathological conditions or because it is unusual to include it in the differential diagnosis. We report a fatal case of granulomatous amoebic encephalitis due to Balamuthia mandrillaris in a 10-year-old girl. We highlight the severity of the brain involvement and the lack of validated schemes for its treatment. Today in the world this infection is considered an emerging disease, influenced by climate change, which calls for being attentive to its presence.

Encefalitis por amebas de vida libre: herramientas actuales para el diagnóstico y tratamiento tempranos / Free-living amoeba encephalitis: current tools for early diagnosis and treatment

Introducción: Naegleria fowleri, Acanthamoeba spp. y Balamuthia mandrillaris son amebas de vida libre que producen daños sustanciales del sistema nervioso central y cuyo diagnóstico premortem es poco frecuente. Objetivo: Proveer una visión general de los aspectos clínico-epidemiológicos y las posibilidades diagnósticas más eficaces en la meningoencefalitis amebiana primaria y la encefalitis granulomatosa amebiana, así como las experiencias de tratamiento expuestas en la literatura reciente. Métodos: Se realizó una revisión bibliográfica sobre las amebas de vida libre. Se analizó la información obtenida de artículos científicos en la base de datos Google Scholar®, PubMed y las citas relacionadas por el programa en PubMed Central. Análisis y síntesis de la información: En primer término del análisis de la meningoencefalitis amebiana primaria y la encefalitis granulomatosa amebiana, resalta la diferenciación de sus características clínicas y epidemiológicas, también que el líquido cefalorraquídeo presenta gran relevancia para el diagnóstico de la meningoencefalitis amebiana primaria. Sin embargo, para los casos presuntivos de la encefalitis granulomatosa amebiana el examen del líquido cefalorraquídeo depende de la valoración riesgo-beneficio y se ha obtenido mayor positividad con el diagnóstico histopatológico de biopsias premortem. En general, se acrecienta la implementación de la investigación del ADN por diferentes métodos que brindan certeza de cada una de las especies de AVL causantes de enfermedad neurológica. 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 útiles a partir de los casos de pacientes que han sobrevivido. Resulta importante tener en cuenta que el diagnóstico rápido de la infección es clave para un tratamiento exitoso(AU)

Introduction: Naegleria fowleri, Acanthamoeba spp. and Balamuthia mandrillaris are free-living amoebae of infrequent premortem diagnosis which cause substantial damage to the central nervous system. Objective: To provide an overview of the clinical-epidemiological aspects and the most effective diagnostic possibilities in primary amebic meningoencephalitis and granulomatous amebic encephalitis, as well as their treatment experiences in recent publications.. Methods: A bibliographic review was conducted about free-living amoebae. An analysis was performed of data obtained from scientific papers published in the databases Google Scholar and PubMed, and the citations listed by the PubMed Central program. Data analysis and synthesis: As principal term of the analysis of primary amebic meningoencephalitis and amebic granulomatous encephalitis, the differentiation of their clinical and epidemiological characteristics stands out, also that cerebrospinal fluid is highly relevant for the diagnosis of primary amebic meningoencephalitis. However, for presumptive cases of amoebic granulomatous encephalitis, the examination of cerebrospinal fluid depends on the risk-benefit assessment and greater positivity has been obtained with the histopathological diagnosis of premortem biopsies. In general, the implementation of DNA research by different methods provided accurate information about each one of the free-living amoeba species that cause neurological disease. Confirmatory culture isolation of N. fowleri, Acanthamoeba spp. and B. mandrillaris revealed growth feasibility differences between diverse media depending on the species and additional limitations. Conclusions: Mortality associated to central nervous system infections caused by free-living amoebae remains high. Studies describing cases of patients who have survived constitute useful material. It is important to bear in mind that fast diagnosis of the disease is crucial to treatment success(AU)

Free-living Acanthamoeba and Naegleria spp. amebae in water sources of León, Nicaragua

free-living amebae (FLA) are known to occur worldwide in water-related biotopes, but only limited information is available on these organisms in developing countries and so far no information on their presence is available from Nicaragua. The aims of this study were to evaluate the prevalence of potentially pathogenic Acanthamoeba spp. and Naegleria spp. in different water sources to which the population of León municipality is exposed. Since pathogenic amebae are thermotolerant, we were especially interested in the occurrence of FLA in geothermal areas. Water samples were collected from León area in Nicaragua: 88 samples were from rivers and springs, 111 from wells, 74 from water taps and 21 from water tanks in urban and suburban León and from three nearby geothermal areas of San Jacinto, Posoltega and Tipitapa. Amebae were identified using morphological and physiological criteria, immunohistochemical staining procedures and molecular methods. Indirect immunofluorescent test was performed on cysts and trophozoites fixed on microscopical slides and incubated for 30 min at room temperature in separate experiments with the following antibodies: rabbit-anti N. fowleri/N. lovanensis (Nf-Pab), mouse monoclonal antibody anti N. fowleri (Nf-5D12u), rabbit antibodies against Acanthamoeba spp. And fluorescent in situ hybridization (FISH) was performed using 18S rRNA-targeted fluorescent oligonucleotide probes. Probes: GSP for the detection of Acanthamoeba and NAEG1088 for the detection of Naegleria. Free-living amebae were recovered from approximately 43 % of the samples. Acanthamoeba spp was found in 21 % of samples from León municipality and in 2 % of samples from geothermal areas. Amoeboflagellates were found in 10 % of samples from León and in 19 % in geothermal areas. Fifty three percent of tested wells in the geothermal area contained thermotolerant amoeboflagellates. Naegleria spp. was identified in 24 out of 39 (61.5 %) of isolated amoeboflagellates. Twelve of them were assigned to N. lovanenesis while none of the isolates could be identified as N. fowleri. However, the common presence of thermotolerant Naegleria in water, specially N. lovanensis, which is an indicator species for N. fowleri, suggests that also this pathogenic amoeba may pose a risk to public health in the area. On the other side, direct pathogenicity, free-living amebae are receiving increasing attention as reservoirs and potential vehicles for the transmission of bacteria in the environment. Thus the information provided in this study may serve as base-line for future studies on the role of free-living amebae e.g. in waterborne-disease outbreaks in the region. Among such potentially important enteropathgens are Vibrio cholerae, E. coli 0157, and Helicobacter pylori. Rev. Biol. Trop. 56 (2): 439-446. Epub 2008 June 30.

Las amebas de vida libre (AVL) son un grupo de organismos de distribución mundial. Entre las AVL hay parásitos facultativos en humanos y otros animales, los cuales pertenecen a los géneros Acanthamoeba, Naegleria y Balamuthia que causan infecciones severas en el sistema nervioso central. Sin embargo no se tiene ninguna información de Nicaragua. El objetivo de este estudio fue evaluar la presencia de amebas de vida libre, en diferentes fuentes de agua de la parte urbana y rural del Departamento de León, y áreas geotérmicas de Nicaragua. Estas amebas fueron identificadas usando criterios morfológicos, fisiológicos, histoquímicos y moleculares. En los resultados se encontró amebas de vida libre en el 43% del total de las muestras. En la municipalidad de León, se encontraron 21% de Acanthamopeba sp. y en las áreas geotérmicas un 2%. Las amebaflagelados tipo Naegleria fueron 10% y 19% respectivamente. Del grupo amebaflagelados fueron 24, de las cuales 12 se dentificaron como N. lovanensis. En estas muestras no se aisló N. fowleri (ameba patógena), sin embargo, la presencia de N. lovanensis es in indicador de la presencia de N. fowleri, la cual puede ser un riesgo a la salud pública. Además, estas amebas pueden servir como vectores de bacterias enteropatógenas.

Comparison of specific activity and cytopathic effects of purified 33 kDa serine proteinase from Acanthamoeba strains with different degree of virulence

The pathogenic mechanism of granulomatous amebic encephalitis (GAE) and amebic keratitis (AK) by Acanthamoeba has yet to be clarified. Protease has been recognized to play an important role in the pathogenesis of GAE and AK. In the present study, we have compared specific activity and cytopathic effects (CPE) of purified 33 kDa serine proteinases from Acanthamoeba strains with different degree of virulence (A. healyi OC-3A, A. lugdunensis KA/E2, and A. castellanii Neff). Trophozoites of the 3 strains revealed different degrees of CPE on human corneal epithelial (HCE) cells. The effect was remarkably reduced by adding phenylmethylsulfonylfluoride (PMSF), a serine proteinase inhibitor. This result indicated that PMSF-susceptible proteinase is the main component causing cytopathy to HCE cells by Acanthamoeba. The purified 33 kDa serine proteinase showed strong activity toward HCE cells and extracellular matrix proteins. The purified proteinase from OC-3A, the most virulent strain, demonstrated the highest enzyme activity compared to KA/E2, an ocular isolate, and Neff, a soil isolate. Polyclonal antibodies against the purified 33 kDa serine proteinase inhibit almost completely the proteolytic activity of culture supernatant of Acanthamoeba. In line with these results, the 33 kDa serine proteinase is suggested to play an important role in pathogenesis and to be the main component of virulence factor of Acanthamoeba.