Potentially pathogenic Acanthamoeba genotype T4 isolated from dental units and emergency combination showers

BACKGROUND Acanthamoeba is the genus of free-living amoebae that is most frequently isolated in nature. To date, 20 Acanthamoeba genotypes have been described. Genotype T4 is responsible for approximately 90% of encephalitis and keratitis cases. Due to the ubiquitous presence of amoebae, isolation from environmental sources is not uncommon; to determine the clinical importance of an isolation, it is necessary to have evidence of the pathogenic potential of amoebae. OBJECTIVE The aim of this study was to physiologically characterise 8 Acanthamoeba T4 isolates obtained from dental units and emergency combination showers and to determine their pathogenic potential by employing different laboratory techniques. METHODS Eight axenic cultures of Acanthamoeba genotype T4 were used in pathogenic potential assays. Osmotolerance, thermotolerance, determination and characterisation of extracellular proteases and evaluation of cytopathic effects in MDCK cells were performed. FINDINGS All of the isolates were osmotolerant, thermotolerant and had serine proteases from 44-122 kDa. Two isolates had cytopathic effects on the MDCK cell monolayer. MAIN CONCLUSION The presence of Acanthamoeba T4 with pathogenic potential in areas such as those tested in this study reaffirms the need for adequate cleaning and maintenance protocols to reduce the possibility of infection with free-living amoebae.

Distribuição das ceratites infecciosas em hospital terciário no Brasil / Distribution of infectious keratitis in a tertiary hospital in Brazil

OBJETIVO: Investigar sazonalidade de ceratities infecciosas em serviço terciário no Brasil. MÉTODOS: Estudo retrospectivo de dados coletados do Laboratório de Microbiologia Ocular do Departamento de Oftalmologia da Universidade Federal de São Paulo de 2005 a 2009. Foram definidas como ceratites infecciosas aquelas com cultura positiva para o agente. Dados foram distribuídos de acordo com os meses do ano e modelos de regressão linear com variáveis "dummy" foram utilizados para testar sazonalidade. RESULTADOS: Foram diagnosticados 1.468 casos de ceratite infecciosa durante o período do estudo. Bactérias foram responsáveis por 80,3% dos casos seguidas por fungos (7%), Acanthamoeba (6%) e casos mistos (6,7%). Testes estatísticos não mostraram sazonalidade para bactérias (p=0,064), fungos (p=0,379), Acanthamoeba (p=0,062) ou casos mistos (p=0,441). CONCLUSÃO: Não foi observada sazonalidade nas ceratites infecciosas em nossa amostra.

PURPOSE: To investigate the seasonality of infectious keratitis in a tertiary hospital in Brazil. METHODS: Charts from the Ocular Microbiology Laboratory of the Department of Ophthalmology of the Federal University of Sao Paulo were reviewed from 2005 to 2009. Infectious keratitis were defined as those with positive culture. Data were distributed monthly and linear regressions with seasonal dummy models were used to test for seasonal trends. RESULTS: Total of 1,468 cases of keratitis was diagnosed during the study period. Bacterial keratitis were reponsible for 80.3% of all cases, followed by fungal (7%), and Acanthamoeba (6%); 6.7% were mixed cases. Statistical tests showed that there were no seasonal trends for bacteria (p=0.064), fungi (p=0.379), Acanthamoeba (p=0.062) or mixed infections (p=0.441). Conclusions: No seasonal trends for infectious keratitis were observed in our sample.

Infection in a rat model reactivates attenuated virulence after long-term axenic culture of Acanthamoeba spp

Prolonged culturing of many microorganisms leads to the loss of virulence and a reduction of their infective capacity. However, little is known about the changes in the pathogenic strains of Acanthamoeba after long culture periods. Our study evaluated the effect of prolonged culturing on the invasiveness of different isolates of Acanthamoeba in an in vivo rat model. ATCC strains of Acanthamoeba, isolates from the environment and clinical cases were evaluated. The in vivo model was effective in establishing the infection and differentiating the pathogenicity of the isolates and re-isolates. The amoebae cultured in the laboratory for long periods were less virulent than those that were recently isolated, confirming the importance of passing Acanthamoeba strains in animal models.

Acanthamoeba spp. como parásitos patógenos y oportunistas / Acanthamoeba spp. as opportunistic pathogens parasites

Among free-living amoeba in nature, species of the genus Acanthamoeba have been associated with human disease. These amoeba are among the most abundant protozoa in nature due to its cosmopolitan distribution and are able to survive in a wide variety of habitats because its low demand for food and in harsh environments by forming structures known as cysts. However, ecological changes and incursion of its different habitats have made this organism can invade a host and live as parasites within him. That's why this type of protozoa are known as amphizoic organism, because human can be constituted as its host, causing infections in the central nervous system, disseminated infections in skin and lungs, and keratitis. Thus, 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. This review summarizes what is known of this kind of free-living amoeba, focusing on the biology, ecology, pathogenesis, diagnosis, treatment and human defense mechanism against infection by the amoeba.

Entre las amebas de vida libre (AVL) que existen en la naturaleza, las especies pertenecientes al género Acantha-moeba han sido asociadas a enfermedades en humanos. Las AVL están entre los protozoos más abundantes en la naturaleza debido a su distribución cosmopolita y a que pueden sobrevivir en una amplia variedad de hábitats, incluyendo ambientes inhóspitos, gracias a su poca demanda de alimento y a que puede formar estructuras conocidas como quistes que las hacen resistentes. Los cambios ecológicos y la incursión de sus diferentes hábitats, han hecho que puedan invadir un hospedero y vivir como parásitos dentro de él. Por esto, este protozoo se conoce como un microorganismo anfizoico, ya que el hombre puede llegar a constituirse como su hospedero, causando infecciones en el sistema nervioso central, infecciones diseminadas en piel y pulmones, y queratitis. Es así como desde el incremento en el número de infecciones reportadas en el mundo por Acanthamoeba, estos protozoos se han convertido en importantes agentes de enfermedades en el hombre. En esta revisión se resume lo que se conoce de este género de AVL, enfocándose en su biología, patogénesis y los mecanismos de defensa humano frente a la infección por Acanthamoeba.

Diagnóstico y tratamiento de queratitis por acanthamoeba / Diagnosis and treatment of keratitis acanthamoeba

OBJETIVO: Revisar las características clínicas, diagnóstico, tratamiento y resultados visuales en pacientes con diagnostico de queratitis por Acanthamoeba (QA). Demostrar la importancia del diagnóstico precoz y de un tratamiento rápido y efectivo. MATERIAL Y MÉTODOS: Estudio retrospectivo de 14 ojos en igual número de pacientes con diagnóstico de QA, tratados en Centro Visión entre Julio 2008 a Junio 2012. Todos los casos fueron confirmados por frotis y/o cultivo. Se formaron dos grupos: precoz y tardío. La terapia se realizó con polihexametilén biguanida y propamidina. Luego de eliminar la infección se registró la agudeza visual final y la duración del tratamiento. RESULTADOS: El grupo más frecuentemente afectado fue entre 21 a 40 años (9 casos). Sólo dos ojos (14,3%) fueron correctamente diagnosticados inicialmente como QA. Once pacientes (78,6%) fueron usuarios de lentes de contacto. El signo más frecuente fue infiltrado difuso (62,3%); el infiltrado perineural sólo se vio en un caso. Cinco pacientes se diagnosticaron dentro de los primeros treinta días (precoz), y nueve casos posteriormente (tardío). La mediana de la agudeza visual postratamiento en el grupo precoz fue 20/40 y en el tardío 20/400. La mediana de la duración del tratamiento en el grupo precoz fue de seis meses y de diez meses en el tardío. CONCLUSIONES: La mayoría de ojos (85,7%) fueron inicialmente catalogados erróneamente como queratitis de otra etiología. Cuando la QA es diagnosticada precozmente, existe un mejor pronóstico visual, y además no será necesario un tratamiento muy prolongado.

OBJETIVES: To review the clinical characteristics, diagnosis, treatment and visual outcome in patients with diagnosis of Acanthamoeba keratitis. To demonstrate the importance of early diagnosis, and prompt and effective treatment. METHODS: Retrospective study of 14 eyes in the same number of patients diagnosed with Acanthamoeba keratitis, which were treated in Centro Visión in the period from July 2008 to June 2012. All cases were confirmed by smear and/or culture. There were two groups: early and late. The treatment was performed with polyhexamethylene biguanide and propamidine as previous protocol. After the cure of the infection, final visual acuity and the duration of treatment were recorded. RESULTS: The most often affected group was between 21-40 years old (9 cases). Only two eyes (14,3%) were initially correctly diagnosed as QA. Eleven patients (78,6%) were contact lens wearers. The most common sign was diffuse infiltrate (62.3%), perineural infiltration was seen in only one case. Five patients were diagnosed within the first thirty days (early group) and nine patients later (late group). The median visual acuity after treatment was 20/40 in the early group, and 20/400 in the late group. The median duration of treatment was six months in the early group, and ten months in the late group. CONCLUSIONS: Most cases (85.7%) were initially erroneously classified as another cause keratitis. When Acanthamoeba keratitis is early diagnosed, there is a better visual prognosis, and also will not need longer treatment.

Hallazgo de acanthamoeba spp en biopsia cerebral de un paciente con adenocarcinoma metastásico / Acanthamoeba spp found in a cerebral biopsy from a patient with metastasic adenocarcinoma

Las amibas de vida libre (AVL) del género Acanthamoeba son parásitos facultativos ampliamente distribuidos en el ambiente, por lo cual el contacto del humano con ellos es frecuente, sin embargo, los reportes de enfermedades producidas por AVL son escasos. La gravedad de éstas justifica su búsqueda, sobre todo cuando la infección es del sistema nervioso central (SNC) y cuando hay compromiso in munológico. En este trabajo se reporta el hallazgo de Acanthamoeba spp en una biopsia cerebral, tomada a un paciente de 44 años de edad con adenocarcinoma. Se exa minó la muestra bajo el protocolo del Laboratorio de Amibiasis, de la Cátedra de Parasitología, Escuela de Bioanálisis, Facultad de Medicina, Universidad Central de Venezuela, para la investigación de AVL y Entamoeba histolytica. Se realizó examen directo y coloraciones especiales, inducción de la flagelación y cultivos a diferentes temperaturas. Se observó crecimiento de Acanthamoeba spp en el medio de Page modificado por Chinchilla y col. (1979), incubado a 37 °C a las 96 horas. La descripción morfológica coincide con la morfología del grupo 3 de Acanthamoeba, según Visvesvara (1991). Se destaca la importancia de la realización del cultivo para el crecimiento e identificación de estos organismos en aquellos laboratorios donde los métodos basados en biología molecular aun no se hayan implementado como parte del diagnóstico y así aplicar el tratamiento oportuno y específico al paciente.

Free-living amoebas (FLA) of genus Acanthamoeba are parasitic facultative organisms whose are widely distributed in the environment, thus the human contact with them is frequent; nevertheless, there are few reports of diseases produced by FLA. The severity of these diseases justifies its re search, mainly when the infection is at central nervous system (CNS) and when there is an immunocompromised host. This work reports the finding of Acanthamoeba spp in a cerebral biopsy from a 44 year-old patient with adenocarcinoma. We followed the protocol established by the Amibiasis Laboratory, Parasitology Chair, School of Bioanalisis, Medicine Faculty, Central University of Venezuela, for the investigation of FLA and Entamoeba histolytica. It wasmade by direct examination of the sample and special stains, flagellation induction and cultures incubated at different temperatures. We observed Acanthamoeba spp growth in biphasic Page media modified by Chinchilla and col. (1979), incubated for 96 hours at 37 °C. The morphologic des cription agrees with the morphology of group 3 of Acanthamoeba, according to Visvesvara (1991). We emphasize the importance of using growth culture for isolation and identification of these organisms in those laboratories where molecular methods has not been implemented yet as part of the diagnosis scheme and thus for applying the opportune and specific treatment to the patient.

Prevalence of potentially pathogenic free-living amoebae from Acanthamoeba and Naegleria genera in non-hospital, public, internal environments from the city of Santos, Brazil

Acanthamoeba and Naegleria species are free-living amoebae (FLA) found in a large variety of natural habitats. The prevalence of such amoebae was determined from dust samples taken from public non-hospital internal environments with good standards of cleanliness from two campuses of the same University in the city of Santos (SP), Brazil, and where young and apparently healthy people circulate. The frequency of free-living amoebae in both campuseswas 39 percent and 17 percent respectively, with predominance of the genus Acanthamoeba. On the campus with a much larger number of circulating individuals, the observed frequency of free-living amoebae was 2.29 times larger (P< 0.00005). Two trophozoite forms of Naegleria fowleri, are the only species of this genus known to cause primary amoebian meningoencephalitis, a rare and non-opportunistic infection. We assume that the high frequency of these organisms in different internal locations represents some kind of public health risk.

Disseminated acanthamoeba infection in a renal transplant recipient: a case report.

Acanthamoeba species are free-living amoebae that are the causative agents of chronic granulomatous meningoencephalitis, amoebic keratitis, pulmonary lesions, cutaneous lesions and sinusitis. Immunocompromised individuals are particularly susceptible to infections with Acanthamoeba, which can be disseminated at times. We herewith report the autopsy findings of disseminated Acanthamoeba infection in a 36-year-old female, a renal transplant recipient on immunosupressants for last four years. Central nervous system showed Acanthamoeba associated chronic granulomatous meningoencephalitis, with predominant perivascular infiltrate of amoebic cysts, trophozoites and inflammatory cells. Both lungs and pancreas also showed infiltration with Acanthamoeba.

Amibas de vida libre y anemia aplástica grave en niños / Aplastic anemia and free-living amoeba in two children

Introducción. Las amibas de vida libre habitualmente viven como fagótrofas en el agua y suelo donde se alimentan de bacterias; también pueden producir infecciones del sistema nervioso central y otros tejidos en seres humanos y animales. La anemia aplástica es una entidad caracterizada por pancitopenia secundaria a disminución de la producción en médula ósea de todos los elementos formes de la sangre y ausencia de enfermedad primaria que infiltre, reemplace o anule la hematopoyesis activa. Casos clínicos. Se presentan 2 niños con historia de sangrados, pancitopenia y el diagnóstico de anemia aplástica grave por biopsia y aspirado de médula ósea, que finalmente fallecieron. Se muestran los hallazgos de amibas de vida libre en la médula. Conclusión. En estos casos no se encontró agente causal de la anemia aplástica, y se sugiere a las amibas como oportunistas del padecimiento.

Disposable contact lens related Acanthamoeba hatchetti keratitis a case report and literature review

Acanthamoeba, is an opportunistic human pathogen of low virulence. Acanthamoeba keratitis is a form of indolent keratitis characterized by remissions and exacerbations, presumably related to the natural cycle of encystation and excystation of the organism. We report herewith a case of Acanthamoeba keratitis in a disposable contact lens wearer. presence of the organism was confirmed by direct smear and culture of a corneal scraping. The patient regained normal vision after the initiation of appropriate therapy. To the best of our knowledge, this is the first report of Acanthamoeba keratitis in Saudi Arabia

possibility of congenital infection with a acanthamoeba culbertsoni

Acanthamoeba culbertsoni is one of the free-living amoebae, which are known to be pathogenic to man, causing granulomatous amoebic encephalitis [GAE]. In this study, Acanthamoeba culbertsoni was isolated from a water sample of El-Mahmoudia Canal in Alexandria, in July 1993. This was used to infect mice intranasally to study the histopathological picture of the brain and lungs. The neuropathological features included chronic granulomatous encephalitis, in which cysts and trophozoites were found. Associated Acanthamoeba pneumonitis with massive consolidation was also observed. Congenital infection of offsprings was reported for the first time in this study

Experimental infection of mice by naegleria fowleri or acanthamoeba culbertsoni isolated from water sites in Egypt

Naegleria fowleri and A. culbertsoni, which are known to cause primary amoebic meningoencephalitis [PAM] were isolated from water sites in Egypt. Each species was tested for pathogenicity in young mice, which were inoculated intracerebrally with amoebae. Mice developed illness and showed signs of menigo encephalitis followed by coma and death within 5 days. The histopathological finding in the brain sections of these animals revealed the same observations as in acute PAM of previous studies. These results proved that N. fowleri and A. culbertsoni isolated from Egypt are pathogenic strains

Detection of free living amoeba [acanthamoeba polyphaga] in the air condition systems

Acanthamoeba polyphaga was found in the cooling towers of the air conditioning systems. This finding directs the attention to more studies on water and air conditioning systems of hospitals and dwellings and the relation to outbreaks of legionnaire's disease be caused by Legionella bacilli which complete its natural life cycle inside the Acanthamoeba

Queratitis por Acanthamoeba sp / Keratitis by Acanthamoeba sp

Desde su primera descripción en 1973 la demostración de Acanthamoeba sp. como causa de queratitis se ha incrementado. De acuerdo a nuestro conocimiento, no se han descripto casos de esta enfermedad en la Argentina. El propósito de esta comunicación es presentar dos pacientes portadores de lentes de contacto que desarrollaron queratitis ulcerada y que en el estudio histopatológico de la córnea obtenida por queratoplastia se demostró quistes de Acanthamoeba sp. El diagnóstico prequirúrgico depende del índice de sospecha del oftalmólogo, para utilizar las técnicas de laboratorio adecuadas. Los resultados del tratamiento médico son controvertidos y la mayoría de los casos requieren una queratoplastia penetrante