Diagnosis and treatment of Acanthamoeba Keratitis: A scoping review demonstrating unfavorable outcomes.

Acanthamoeba spp. are pathogens that cause Acanthamoeba keratitis (AK), a serious cornea inflammation that can lead to gradual loss of vision, permanent blindness, and keratoplasty. The efficacy of AK treatment depends on the drug's ability to reach the target tissue by escaping the protective eye barrier. No single drug can eradicate the living forms of the amoeba and be non-toxic to the cornea tissue. The treatment aims to eradicate both forms of protozoan life but is hampered by the resistance of the cysts to the most available drugs, leading to prolonged infection and relapses. Drug therapy is currently performed mainly using diamidines and biguanides, as they are more effective against cysts. However, they are cytotoxic to corneal cells. Drugs are applied topically, and hourly. Over time, the frequency of administration decreases, but the treatment time varies from month to years. This study aims to obtain an up-to-date summary of the literature since 2010, allowing us to identify the trends and gaps and address future research involving new alternatives for treating AK. The results were divided into three phases, pre-treatment, empirical treatment, and the treatment after diagnosis confirmation. The drugs prescribed were stratified into antiamoebic, antibiotic, antifungal, antivirals, and steroids. It was possible to observe the transition in drug prescription during three different stages until the diagnosis was confirmed. There were more indications for antibiotic, antifungal, and antiviral drugs in the early stages of the disease. The antiamoebic drugs were only prescribed after exhausting other treatments. This can be directly involved in developing complications and no responsiveness to medical treatment.

Clinical and molecular diagnosis of Acanthamoeba keratitis in contact lens wearers in southern Brazil reveals the presence of an endosymbiont.

Acanthamoeba keratitis (AK) is an infection that is mostly observed in contact lens wearers. It is often misdiagnosed causing delays in the administration of the correct treatment. The aim of this study was to report the outcome of clinical and molecular diagnosis of AK cases during the summer of 2019 in the southern region of Brazil. Three suspected cases of AK were discovered after an ophthalmic examination at a public hospital in the city of Porto Alegre. These cases were then confirmed through laboratory diagnosis (cell culture and molecular analysis by PCR and sequencing). In each of the three clinical sample cell cultures of corneal scraping and molecular analysis confirmed the presence of Acanthamoeba spp., all belonging to the morphological group II and to the genotype T4, which is the most common genotype associated with AK. In addition, Acanthamoeba spp. isolated from one of the clinical samples was found to harbor the Candidatus Paracaedibacter acanthamoeba, a bacterial endosymbiont. The presence of Ca. Paracaedibacter acanthamoeba in clinical isolates requires further research to reveal its possible role in the pathogenicity of Acanthamoeba infections.

Cromoforo fotoactivado con crosslinking como tratamiento para la queratitis por Acanthamoeba / Photoactivated chromophore with crosslinking as treatment for Acanthamoeba keratitis

RESUMEN Se reporta el uso del crosslinking como tratamiento de la queratitis por Acanthamoeba en una serie de 7 pacientes quienes acudieron al Servicio de Córnea por queratitis multitratadas. Se les realizó biopsia corneal, la cual se cultivó en solución de Page. Los pacientes fueron tratados con un protocolo de PACK-CXL durante más de 5 minutos y fueron sometidos a la exposición a la luz UV-A. El edema del nuevo epitelio era de 2 cruces a las 24 horas, y desapareció a las dos semanas del procedimiento en todos los casos. El porcentaje de desepitelización basal al momento del diagnóstico fue de 75,7 por ciento. La agudeza visual mejor corregida fue de entre 20/20 y 20/30. Se concluye que el uso de crosslinking en pacientes con Acanthamoeba en fases inicales pudiera ser una opción terapéutica segura y efectiva(AU)

ABSTRACT A report is presented of the use of crosslinking as treatment for Acanthamoeba keratitis in a series of 7 patients attending the Cornea Service for multitreated keratitis. Corneal biopsy was performed, which was cultured in Page solution. The patients were treated with a PACK-CXL protocol for more than 5 minutes and subjected to UV-A light exposure. Edema of the new epithelium was 2 crosses at 24 hours and disappeared 2 weeks after the procedure in all cases. Basal de-epithelialization percentage at diagnosis was 75.7 percent. Best corrected visual acuity ranged between 20/20 and 20/30. It is concluded that the use of crosslinking in patients with Acanthamoeba keratitis in its initial stages could be a safe and effective therapeutic option(AU)

Infectious keratitis in southern Brazil: a comparison culture negative and culture positive patients / Ceratite infecciosa no sul do Brasil: comparação entre pacientes com cultura negativa e positiva

Abstract Purpose: To compare clinical-epidemiological profile and treatment outcome between culture negative and culture positive keratitis patients. Methods: Patients with suspected infectious keratitis seen at two ophthalmic hospitals in Curitiba, Brazil, between June 2014 and April 2016, were prospectively studied. Ophthalmological exam with corneal scraping and microbiological tests were performed. Data regarding follow up, surgical interventions and treatment outcome were collected after 12 weeks of the first visit trough medical chart review. From the results of the culture, two groups were formed: culture negative keratitis (CNK) and culture positive keratitis (CPK). Results: According to inclusion criteria 21 patients were classified as culture negative keratitis and 20 patients as culture positive keratitis. The number of patients on antibiotic drops at the first visit was greater in CNK group (90.5% versus 60%; p=0.032). Surgical procedures were necessary in 3 patients (15%) in CNK group and in 7 patients (36,8%) in CPK group (p=0.155). Treatment success was achieved by 85% (17/20) of the patients in CNK group and by 61% (11/18) of the patients in CPK group (p=0.144). There was no significant difference between groups regarding age, gender, place of residence, presence of comorbidities, risk factors for infectious keratitis, duration of symptoms and characteristics of corneal ulcer. Conclusions: Previous treatment with antibiotics correlates with negative culture results. There was no significant difference in treatment outcome between culture negative and culture positive keratitis patients.

Resumo Objetivo: Comparar os perfis clinico-epidemiológicos e os desfechos entre pacientes com ceratite com cultura positiva e pacientes com ceratite com cultura negativa. Métodos: Pacientes com ceratite infecciosa, atendidos em dois hospitais oftalmológicos em Curitiba, Brasil, entre junho de 2014 e abril de 2016, foram estudados prospectivamente. Exame oftalmológico, raspado de córnea e exames microbiológicos foram realizados no primeiro atendimento. Os dados quanto a seguimento e desfecho foram coletados após 12 semanas do primeiro atendimento através de revisão de prontuário. A partir dos resultados das culturas, dois grupos foram formados: ceratite com cultura negativa e ceratite com cultura positiva. Resultados: Vinte e um pacientes foram classificados como ceratite com cultura negativa e 20 como ceratite com cultura positiva. O número de pacientes em uso de colírio antibiótico no primeiro atendimento foi maior no grupo de cultura negativa (90,5% versus 60%; p=0,032). Sete pacientes (37%) no grupo cultura positiva precisaram de procedimentos cirúrgicos no manejo da ceratite, versus 3 pacientes (15%) do grupo cultura negativa (p=0,155). Oitenta e cinco por cento (17/20) dos pacientes do grupo cultura negativa alcançaram sucesso no tratamento, contra 61% (11/18) dos pacientes no grupo cultura positiva (p=0,144). Não houve diferença entre os grupos quanto a idade, gênero, local de procedência, presença de comorbidades, fatores de risco, duração dos sintomas e características da úlcera de córnea. Conclusão: Tratamento prévio com colírio de antibiótico correlaciona-se com resultados negativos de cultura. Não houve diferença no desfecho após tratamento entre os pacientes com cultura negativa e cultura positiva.

Situación del diagnóstico de Queratitis Amebiana en Paraguay / Status of the diagnosis of Amebic Keratitis in Paraguay

Las amebas de vida libre (AVL) existen ampliamente distribuidas en la naturaleza, donde el género Acanthamoeba es la más frecuentemente aislada en diversos ambientes del suelo, aire y agua y está asociada a enfermedades en humanos. Su capacidad para vivir en ambientes adversos se debe a su baja demanda de alimentación y a que en su ciclo biológico tiene un estadio en forma de quiste, lo que la hace muy resistente. El hombre, como hospedero puede desarrollar infecciones en el sistema nervioso central, en la piel y los pulmones. A nivel ocular es capaz de afectar la córnea y producir queratitis. Por lo tanto es considerado un importante agente etiológico de patologías humanas. En esta revisión se aborda la biología, patogénesis y los mecanismos de defensa del ser humano frente a la infección por Acanthamoeba. Además a esto, de los factores de riesgo por el uso de lentes de contacto y malos hábitos de higiene del usuario y por último el abordaje diagnóstico microbiológico y molecular. Esta herramienta ha ido mejorando con el avance de la tecnología, indispensable para la temprana identificación y el logro de una oportuna y eficaz intervención clínica y terapéutica. Finalmente exponemos la situación actual en relación a los métodos de diagnóstico con que se cuentan y los escasos reportes clínicos existentes en Paraguay. Palabras clave: Acanthamoeba sp., Lentes de contacto, Queratitis.

Free-living amoeba (FLA) exist widely in nature, where the genus Acanthamoeba is the most frequently isolated in various environments of soil, air and water. It is associated with diseases in human. Its ability to live in adverse environments is due to the low food demand and that in its biological cycle it has a cyst-shaped stage, which makes it very resistant. Man, as a host, can acquire infections in the central nervous system and in the skin and lungs. On the ocular level, it can affect the cornea and cause keratitis. Therefore, it is considered an important etiological agent of human pathologies. This review addresses the biology, pathogenesis and human defense mechanisms against Acanthamoeba infection. In addition to this, the review explores the risk factors related to the use of contact lenses and poor hygienic behavior of the users, and finally the microbiological and molecular diagnosis. This particular tool has been improved with the advancement of technology and is essential for timely identification and the achievement of a good clinical and therapeutic intervention. Finally, we present the current situation in Paraguay regarding the few existing clinical reports and the diagnostic methods available. Key words: Acanthamoeba sp., Contact lenses, Keratitis.

Effectiveness of sampling methods employed for Acanthamoeba keratitis diagnosis by culture.

PURPOSE: This retrospective, observational study was designed to evaluate the effectiveness of the sampling methods commonly used for the collection of corneal scrapes for the diagnosis of Acanthamoeba keratitis (AK) by culture, in terms of their ability to provide a positive result. METHODS: A total of 553 samples from 380 patients with suspected AK received at the Parasitology Section of the Public Health Institute of Chile, between January 2005 and December 2015, were evaluated. A logistic regression model was used to determine the correlation between the culture outcome (positive or negative) and the method for sample collection. The year of sample collection was also included in the analysis as a confounding variable. RESULTS: Three hundred and sixty-five samples (27%) from 122 patients (32.1%) were positive by culture. The distribution of sample types was as follows: 142 corneal scrapes collected using a modified bezel needle (a novel method developed by a team of Chilean corneologists), 176 corneal scrapes obtained using a scalpel, 50 corneal biopsies, 30 corneal swabs, and 155 non-biological materials including contact lens and its paraphernalia. Biopsy provided the highest likelihood ratio for a positive result by culture (1.89), followed by non-biological materials (1.10) and corneal scrapes obtained using a modified needle (1.00). The lowest likelihood ratio was estimated for corneal scrapes obtained using a scalpel (0.88) and cotton swabs (0.78). CONCLUSION: Apart from biopsy, optimum corneal samples for the improved diagnosis of AK can be obtained using a modified bezel needle instead of a scalpel, while cotton swabs are not recommended.

The first Acanthamoeba keratitis case in the Midwest region of Brazil: diagnosis, genotyping of the parasite and disease outcome.

We report an Acanthamoeba keratitis case associated with the use of contact lens in a 28-year-old female from Brasília, Brazil. Samples from corneal scraping and contact lens case were used for culture establishment, PCR amplification, and partial sequencing (fragments of ~400kb) of small subunit rDNA; both culture and PCR were positive. The sequence analyses of the cornea and of isolates from the contact lens case showed similarity with the T4 genotype. To the best of our knowledge, this is the first report of T4 Acanthamoeba keratitis case from the Midwest region of Brazil.

The first Acanthamoeba keratitis case in the Midwest region of Brazil: diagnosis, genotyping of the parasite and disease outcome

Abstract We report an Acanthamoeba keratitis case associated with the use of contact lens in a 28-year-old female from Brasília, Brazil. Samples from corneal scraping and contact lens case were used for culture establishment, PCR amplification, and partial sequencing (fragments of ~400kb) of small subunit rDNA; both culture and PCR were positive. The sequence analyses of the cornea and of isolates from the contact lens case showed similarity with the T4 genotype. To the best of our knowledge, this is the first report of T4 Acanthamoeba keratitis case from the Midwest region of Brazil.

Contact lens-related polymicrobial keratitis: Acanthamoeba spp. genotype T4 and Candida albicans.

A 31-year-old female daily user of contact lenses sought medical attention, reporting blurred vision and irritation of the left eye. Slit-lamp examination revealed hyperemia and an irregular corneal epithelium surface, and empirical treatment was started. A corneal scrape was obtained and examined for the presence of fungi, bacteria, and Acanthamoeba spp. The results of the microbial culture revealed growth of Acanthamoeba spp. and Candida albicans. The Acanthamoeba isolate was characterized by cyst morphology as belonging to group II according to Pussard and Pons. Sequencing of the diagnostic fragment 3 (DF3) region located on the 18S ribosomal DNA identified the isolate as genotype T4. The patient was treated with chlorhexidine 0.02% and polyhexamethylene biguanide (PHMB) 0.02% drops for 5 months until the infection resolved. Lately, rare cases of polymicrobial keratitis associated with Acanthamoeba and Candida albicans have been reported. Cases of co-infection are more difficult to treat, since the specific treatment depends on precise identification of the agents involved.

Acanthamoeba keratitis in Porto Alegre (southern Brazil): 28 cases and risk factors.

The increasing use of contact lenses worldwide has led to an increase in cases of Acanthamoeba keratitis, which are often associated with inappropriate cleaning of contact lenses and lens cases. This study aimed to retrospectively review 28 cases of Acanthamoeba keratitis in Porto Alegre (southern Brazil) and identify the risk factors and clinical outcomes of affected patients. Most patients had higher education (66.6%), all were users of contact lenses, mostly women (67.9%). Most patients were soft contact lens wearers (66.7%) and 85.7% used multipurpose cleaning solutions. Sixteen patients (64.0%) used to wear contact lenses while swimming and/or bathing. Pain was the most common symptom (92.6%). For treatment, patients used polyhexamethylene biguanide drops (92.6%), propamidine isethionate drops (81.5%), chlorhexidine drops (55.6%), topical corticosteroids (63.0%), and systemic corticosteroids (37.0%). Herpes simplex keratitis was the most common misdiagnosis (72.7%). The majority of patients (76.0%) underwent a corneal transplant to control the disease.

Molecular and morphological characterization of Acanthamoeba isolated from corneal scrapes and contact lens wearers in Argentina.

In this study, we describe the frequency of Acanthamoeba keratitis (AK) in patients that assisted in the Ophthalmology Department and determine the species/genotypes of free living amoebas (FLA) isolates. FLA from Corneal scrapes (CS) and contact lens (CL) wearers were studied by morphological and molecular characterization. A database was constructed with sociodemographic, clinical findings and history of use of CL variables. During January 2000 and September 2016 patients with corneal pathology admitted to the Ophthalmology Service of the University Hospital in Córdoba city, Argentina were included in the study. FLA were detected in 1.5% (11/739) and in 17% (11/65) of CS and CL analyzed respectively. FLA isolates from CL users evidenced an 80.9% of inappropriate lens maintenance, 4.8% (1/21) were not CL users that have been in contact with waters in outdoor environment and 14,3% (3/21) with no data about CL users. Acanthamoeba was confirmed in 100% and 82% of CS and LC respectively. The most frequent symptom associated with AK was red eye and photophobia. FLA from CS belonged to group II but 82% (9/11) and 18% (2/11) from CL belonged to group II and III respectively. T4 genotype and A. polyphaga species were detected in 100% of Acanthamoeba isolates. Poor CL hygiene practices, highlights the need for improved education about the severity of AK and consequences of improper CL hygiene. Genotype T4 detected in 100% of both CS and CL samples, consistently with previous findings indicating that this genotype is by far the most prevalent isolated from ocular infection.

Molecular diagnosis of Acanthamoeba keratitis: evaluation in rat model and application in suspected human cases.

Acanthamoeba keratitis (AK) is a progressive corneal infection that demands rapid and sensitive techniques for diagnosis to avoid risk of visual impairment. We evaluated two DNA extraction techniques and a semi-nested-PCR (snPCR) targeting the 18S rRNA gene to detect Acanthamoeba cysts and trophozoites. The most effective protocol was evaluated in samples of corneal scrapings and biopsies from an AK rat model and applied to diagnosis of human cases of AK. DNA extraction performed with a commercial kit based on DNA binding to magnetic beads was more efficient than a method based on alkaline lysis, allowing the detection of one trophozoite and one cyst of Acanthamoeba in samples prepared from cultures. This technique and sn-PCR were applied in corneal scrapings of rats experimentally infected with Acanthamoeba (n = 6), resulting in 100% of positivity, against 16.7% (n = 6) of positive identification in culture method using non-nutrient agar (NNA) with Escherichia coli. Corneal biopsies from rats were also tested (n = 6) and resulted in positivity in all samples in both molecular and culture methods. Eight out of ten presumptive human cases of Acanthamoeba keratitis were also confirmed by sn-PCR of scrapping samples, while the culture method was positive in only four cases. We discuss that animal model of AK can be an efficient tool to validate diagnostic methods and conclude that DNA extraction with the kit and snPCR protocol described here is an effective alternative for diagnosis of AK.

Acanthamoeba genotypes T3 and T4 as causative agents of amoebic keratitis in Mexico.

Free-living amoebae (FLA) are widely distributed worldwide. Some genera included in this group act as opportunistic pathogens causing fatal encephalitis and Acanthamoeba keratitis (AK), a sight-threatening infection of the cornea associated with the use of soft contact lenses that could even end in blindness if an early diagnosis and treatment are not achieved. Furthermore, the numbers of AK cases keep rising worldwide mainly due to an increase of contact lens wearers and lack of hygiene in the maintenance of lenses and their cases. In Mexico, no cases of AK have been described so far although the isolation of other pathogenic FLA such as Naegleria fowleri and Balamuthia mandrillaris from both clinical and environmental sources has been reported. The present study reports two cases of Acanthamoeba keratitis diagnosed in two patients admitted to the Hospital "Luis Sánchez Bulnes" for Blindness Prevention in Mexico City, Mexico. Corneal scrapes and contact lenses were checked for the presence of Acanthamoeba strains in both patients. Strains were axenized after initial isolation to classify at the genotype level. After sequencing the diagnostic fragment 3 (DF3) region located on the 18S ribosomal DNA (rDNA) gene of Acanthamoeba, genotype T3 and genotype T4 were identified in clinical case 1 and 2, respectively. To our knowledge, these are the first reported cases of AK in Mexico in the literature and the first description of Acanthamoeba genotypes T3 and T4 as causative agents of amoebic infection.

Comparison of Validated Polymerase Chain Reaction and Culture Isolation for the Routine Detection of Acanthamoeba From Ocular Samples.

PURPOSE: Acanthamoeba keratitis should be definitively diagnosed for appropriate therapy. Our institution has validated polymerase chain reaction (PCR) as a routine diagnostic test to detect Acanthamoeba DNA from ocular samples. We compared PCR with culture isolation for detecting Acanthamoeba from ocular samples. METHODS: The microbiology records of patients that had specimens submitted (May 2012 to January 2014) for laboratory testing for Acanthamoeba keratitis were reviewed for (1) Acanthamoeba culture isolation, (2) Acanthamoeba DNA detection by PCR, and (3) non-Acanthamoeba culture results. For Acanthamoeba isolation, corneal samples were planted on nonnutrient agar overlaid with Enterobacter aerogenes. Validated PCR (May 2012) for Acanthamoeba DNA was processed at the Division of Molecular Diagnostics, UPMC, Pittsburgh, PA. Additional cultures were obtained for bacteria, fungus, and virus (i.e., herpes simplex virus) using standard techniques. RESULTS: Culture isolation and PCR were processed on 125 patients with a differential diagnosis of Acanthamoeba keratitis. Of these, 104 (83.2%) were culture negative, PCR negative; 14 (11.2%) were culture positive, PCR positive; 4 (3.2%) were culture negative, PCR positive; and, 3 (2.4%) were culture positive, PCR negative. Culture and PCR were statistically equivalent for detecting Acanthamoeba from ocular samples (P=1.0, McNemar's test). Nineteen of the culture-negative, PCR-negative corneal samples (18.3%) were positive for other pathogens such as bacteria, fungus, and virus. CONCLUSIONS: There is no clear advantage of PCR over culture isolation for detecting Acanthamoeba in ocular specimens. Other pathogens such as bacteria, fungus, and virus must still be considered in severe persistent keratitis. Polymerase chain reaction seems to be a complementary test for the clinical support of Acanthamoeba keratitis.

[Acanthamoeba sp.: a case report in a non-contact lens wearer]. / Acanthamoeba sp.: un caso de queratitis no relacionada con el uso de lentes de contacto.

Acanthamoeba sp. keratitis is generally related to wearing contact lenses, and, to a lesser extent, to contaminated water. It is characterized by reduced visual capacity and the presence of severe ocular pain. Clinically, it can be mistaken for a herpes infection. if it is not diagnosed, and timely and adequately treated, it can result in corneal perforation and, eventually, in vision loss. One of the few registered cases of Acanthamoeba sp. keratitis not related to the use of contact lenses is herein reported.

[Acanthamoeba sp. keratitis: first case confirmed by isolation and molecular typification in Bahía Blanca, Buenos Aires Province, Argentina]. / Queratitis por Acanthamoeba sp.: primer caso confirmado por aislamiento y tipificación molecular en Bahía Blanca, provincia de Buenos Aires, Argentina.

Some species of the Acanthamoeba genus cause keratitis, a very painful, most likely unilateral corneal infection , associated with eye and vision impairment. We here present a case of a 31-year-old female patient, a regular user of soft contact lenses without good practices of lens hygiene and handling. The patient attended medical consultation after two months of inflammation and pain in her right eye. After ophthalmological studies, and due to suspicion of a parasitic infection, a biopsy was performed and the sample submitted for bacteriological and parasitological analyses. Moreover, contact lens holders and lens cleaning solutions were studied. The samples yielded negative results for bacterial infection. However, cultivation of all samples showed the presence of amoeboid parasites. Isolated amoebae were morphologically and molecularly classified as members of the Acanthamoeba genus. This is the first case of keratitis caused by Acanthamoeba in Bahía Blanca, Buenos Aires Province, where the parasite was identified by specific and sensitive molecular techniques.

Citologia de impressão no diagnóstico de infecção corneana por Acanthamoeba: relato de caso / Diagnosis of Acanthamoeba corneal infection by impression cytology: case report

Relatamos três casos de infecção corneana por Acanthamoeba sp em que foi possível detectar cistos do microorganismo com a técnica de citologia de impressão. Três pacientes encaminhados ao Laboratório de Doenças Externas Oculares em 2004 com alterações superficiais da córnea foram submetidos ao exame de citologia de impressão para investigação da presença de cistos de Acanthamoeba sp. Duas amostras foram obtidas da córnea de cada paciente e coradas com PAS, hematoxilina e Papanicolaou. Investigação microbiológica de rotina e cultura também foram realizadas após raspado da córnea. O cultivo das amostras e a citologia de impressão foram positivas para Acanthamoeba sp em todos os pacientes, ao passo que os raspados corados com Giemsa foram positivos em dois casos. A citologia de impressão revelou cistos de Acanthamoeba sp entre feixe de células epiteliais corneanas e como células isoladas. Foram observados cistos no epitélio de um dos pacientes com a citologia de impressão após três meses de tratamento, enquanto o raspado foi negativo. No exame anatomopatológico observaram-se cistos no epitélio e estroma de uma córnea receptora de um dos pacientes após transplante. Neste estudo, a citologia de impressão detectou com sucesso cistos de Acanthamoeba sp em pacientes com acometimento epitelial. Por tratar-se de método não invasivo, a técnica pode ser usada para facilitar o diagnóstico mais precoce da infecção por Acanthamoeba, sendo útil também no acompanhamento do tratamento da doença.

To describe three cases of corneal infection due to Acanthamoeba sp in which was possible to detect Acanthamoeba sp cysts by the corneal impression cytology technique. Three patients referred to the External Eye Disease Laboratory in 2004 with superficial corneal alterations were submitted to corneal specimen collection by impression cytology filter paper to investigate the presence of Acanthamoeba sp cysts. Two impression cytology samples were obtained from each patient and were stained by PAS, hematoxylin and Papanicolaou. Routine microbiological investigation and culture were also performed using corneal scraping. Positive culture and impression cytology for Acanthamoeba sp was observed in all patients while smears with Giemsa stain were positive in two. Impression cytology Acanthamoeba sp cysts were observed among sheets of corneal epithelial cells and as isolated cells. Cysts were also found in the superficial epithelium in one of these patients after treatment while corneal scraping did not reveal any cyst. Histopathology revealed cysts in the epithelium and stroma in a transplanted cornea in one of these patients. The first description of impression cytology as a diagnostic method for Acanthamoeba keratitis occurred recently. In this study corneal impression cytology detected Acanthamoeba sp cysts successfully in these patients with only superficial involvement. Impression cytology as a non invasive technique can be used to facilitate early recognition of Acanthamoeba infection playing a useful role in the follow-up of the disease.

Confocal microscopy in early diagnosis of Acanthamoeba keratitis.

PURPOSE: This study correlated confocal microscopic images obtained using the Nidek ConfoScan 2.0 System in corneas with clinical suspicion of Acanthamoeba keratitis, with diagnosis confirmed by either cytological and/or histological analysis. METHODS: Fifteen eyes of 14 patients with a clinical diagnosis of Acanthamoeba keratitis underwent confocal microscopy evaluation. RESULTS: Fifteen eyes of 14 patients (one bilateral case) showed Acanthamoeba keratitis alterations that ranged from massive infestation to cicatricial opacity in the stroma. Ten patients (71%) were females. Mean age was 26 years (range 19 to 37 yr). All patients were contact lens wearers. CONCLUSION: Confocal microscopy was a useful, noninvasive technique in the diagnosis and treatment of Acanthamoeba keratitis, especially in those cases in which corneal scraping, cytological analysis, and culture are negative. It also eliminated the necessity of tissue biopsy, considered an invasive procedure.

Ceratite por Acanthamoeba / Acanthamoeba for ceratite

Amebas de vida livre (AVL) säo protozoários amplamente dispersos na natureza. Já foram identificados no solo, ar, água doce e do mar, poeira e também na orofaringe de humanos saudáveis, entre outros. A presença das AVL está associada a fungos, bactérias, outros protozoários e até mesmo algas que säo utilizados como substrato alimentar. As AVl näo requerem um hospedeiro em seu ciclo vital ("vida livre") e as infecçöes säo consideradas acidentais (como nos casos de meningites agudas por Naegleria sp) ou oportunistas (como meningites granulomatosas, oites entre outras doenças causadas por Acanthamoeba sp).

Ceratite por Acanthamoeba: relato de casos no Rio Grande do Sul / Acanthamoeba keratitis: report of cases in Rio Grande do Sul

Relato de três primeiros casos comprovados de ceratite por Acanthamoeba sp no Rio Grande do Sul. Todos os pacientes eram usuários de lentes rígidas gás-permeáveis, usando água corrente para higiene das mesmas. Um paciente teve resoluçäo do quadro clínico após 4 meses de tratamento intensivo com neomicina, biguanida, metronidazol e dexametasona tópicos. Os outros pacientes necessitaram de ceratoplastia penetrante, um após 2 meses e o outro após 14 meses de tratamento clínico intensivo (neomicina, biguanida, propamidine e dexametasona tópicos) sem sucesso. Näo houve recidiva da infestaçäo por Acanthamoeba em nenhum dos casos durante o período de seguimento (16,5 e 22 meses). O diagnóstico etiológico foi realizado pela identificaçäo de cistos e trofozoítos de Acanthamoeba no exame direto do raspado da úlcera de córnea em dois pacientes e no exame anátomo-patológico dos botöes corneanos dos que se submeteram ao transplante de córnea