Incidence of Acanthamoeba Keratitis in the United Kingdom in 2015: A Prospective National Survey.

PURPOSE: The aims of this study were to quantify the incidence of Acanthamoeba keratitis (AK) in the United Kingdom and investigate risk factors and management parameters. METHODS: This was a prospective population-based study from January to December 2015 through the British Ophthalmic Surveillance Unit. Data were collected on demographics, clinical features, and management. Incidence rates were calculated from estimates of population and contact lens (CL) user numbers. Statistical analysis compared annualized incidences per million and altered risk ratios for AK with the England and Wales 24 months 1997/1998 to 1998/1999 study. RESULTS: The study identified 124 AK cases, an overall incidence of 2.35 per million. CL wearers accounted for 108 of 124 cases (87%), in whom the AK incidence was 26.94 per million. Herpes keratitis was initially misdiagnosed in 25 of 124 cases (20.2%). The highest incidence of AK was among planned replacement soft CL (PRSCL) wearers (50.65 per million), 7-fold greater than for daily disposable CL (DDSCL) users (7.24 per million). There was a significant increase in AK incidence ( P < 0.001) compared with both 1997/1998 [risk ratio 1.92, 95% confidence interval (CI) 1.38-2.66] and 1998/1999 (risk ratio 2.13, 95% CI 1.52-2.98) together with a higher incidence per million CL users of 26.94 versus 21.14 (1997/1998) and 17.53 (1998/1999). CONCLUSIONS: This study provides the first published data on the nationwide incidence of AK in the United Kingdom. The findings confirm an increasing incidence of AK, particularly among contact lens wearers since 1997/1998 to 1998/1999. PRSCLs were identified as a significant risk factor compared with DDSCLs. Misdiagnosis and treatment delays remain an ongoing problem for patients with AK.

Lately Diagnosed Acanthamoeba Keratitis Manifesting as an Intrastromal Corneal Abscess: A Case Report.

ABSTRACT: A 42-year-old female contact lens wearer presented to a local emergency department with a 3-day history of decreased vision and ocular discomfort in her right eye. She was started on topical fluorometholone and oral acyclovir with initial diagnosis of herpes simplex keratitis. After 3 weeks of worsening symptoms, she was diagnosed with bacterial corneal ulcer and treated with levofloxacin eye drops every 2 hr. After 14 days of no improvement, she was referred to our clinic for further workup. Slitlamp examination demonstrated a solitary dense 3×3-mm infiltration involving anterior and central corneal stroma. The overlying epithelium was intact, and there was no subepithelial infiltration, radial perineuritis, keratic precipitates, or anterior chamber reaction. Corneal sensation was normal. Confocal microscopy and corneal biopsy were definitive for Acanthamoeba infection. The patient received polyhexamethylene biguanide 0.02% every 2 hr and oral ketoconazole 200 mg twice a day, which resulted in improvement in her signs and symptoms within 10 days. The medications were gradually tapered off over 5 months per clinical response. At the 9-month follow-up visit, the best-corrected visual acuity was 5/10 with a superficial central stromal scar at slitlamp examination. Acanthamoeba infection should be considered in contact lens wearers who present with intrastromal corneal abscess.

Acanthamoeba Keratitis Risk Factors for Daily Wear Contact Lens Users: A Case-Control Study.

PURPOSE: This study was designed to establish risk factors for the development of Acanthamoeba keratitis (AK) for daily disposable (DD) contact lens (CL) users compared with daily wear (DW) reusable lens users and for risks unique to DD users. This is important because, in many major economies, CL use is the principal cause of microbial keratitis, of which AK accounts for approximately 50% of cases with sight loss. Determining these AK risks informs practitioner advice and consumer behavior. DESIGN: Case-control study. PARTICIPANTS: Cases and controls were recruited from an Accident and Emergency Department serving South-East England. Cases were new CL users with AK recruited retrospectively from January 2011 to February 2013 and prospectively thereafter until August 2014. Controls were recruited prospectively from February 2014 to June 2015. METHODS: Analysis of a self-administered questionnaire. MAIN OUTCOME MEASURES: Independent risk factors and population attributable risk percentage (PAR%) for AK. RESULTS: A total of 83 AK cases and 122 controls were recruited; DD use was reported by 20 (24%) cases and 66 (54%) controls. In multivariable analyses adjusted for potential confounders, the odds of AK was higher for DW reusable soft lenses (odds ratio [OR], 3.84; 95% confidence interval [CI], 1.75-8.43) and rigid lenses (OR, 4.56; 95% CI, 1.03-20.19) than for DD lenses. Within the DD-using subset, AK was associated with the following modifiable risk factors: less frequent professional follow-up visits (OR, 10.12; 95% CI, 5.01-20.46); showering in lenses (OR, 3.29, 95% CI, 1.17-9.23); lens reuse (OR, 5.41; 95% CI, 1.55-18.89); and overnight wear (OR, 3.93; 95% CI, 1.15-13.46). The PAR% estimated that 30% to 62% of cases could be prevented by switching from reusable soft lens to DD lens use. CONCLUSIONS: Acanthamoeba keratitis risks are increased > threefold in DW reusable lens users versus DD lens use. Acanthamoeba keratitis risks for DD lens users can be minimized by adherence to safe use guidelines (no reuse, overnight wear, or contamination by water). Safe CL use can be improved by increasing the prominence of risk avoidance information from manufacturers and regulators. Because AK accounts for half of severe keratitis in CL users, these measures can be expected to have public health benefits.

Dual-Mode Gold Nanoparticle-Based Method for Early Detection of Acanthamoeba.

Acanthamoeba keratitis is an aggressive and rapidly progressing ocular pathology whose main risk factor is the use of contact lenses. An early and differential diagnosis is considered the main factor to prevent the progression and improve the prognosis of the pathology. However, current diagnosis techniques require time, complex and costly materials making an early diagnosis challenging. Thus, there is a need for fast, accessible, and accurate methods for Acanthamoeba detection by practitioners for timely and suitable treatment and even for contact lens user as preventive diagnosis. Here, we developed a dual-mode colorimetric-based method for fast, visual, and accurate detection of Acanthamoeba using gold nanoparticles (AuNPs). For this strategy, AuNPs were functionalized with thiolated probes and the presence of target Acanthamoeba genomic sequences, produce a colorimetric change from red to purple. This approach allows the detection of 0.02 and 0.009 µM of the unamplified Acanthamoeba genome by the naked eye in less than 20 min and by color analysis using a smartphone. Additionally, real samples were successfully analyzed showing the potential of the technology considering the lack of point-of-care tools that are mostly needed.

A novel montmorillonite clay-cetylpyridinium chloride complex as a potential antiamoebic composite material in contact lenses disinfection.

BACKGROUND: Acanthamoeba keratitis is a painful, sight-threatening infection. It is commonly associated with the use of contact lens. Several lines of evidence suggest inadequate contact lens solutions especially against the cyst forms of pathogenic Acanthamoeba, indicating the need to develop effective disinfectants. OBJECTIVE: In this work, the application and assessment of montmorillonite clay (Mt-clay), cetylpyridinium chloride (CPC) and cetylpyridinium chloride-montmorillonite clay complex (CPC-Mt) against keratitis-causing A. castellanii belonging to the T4 genotype was studied. METHODS: Adhesion to human cells and amoeba-mediated cytopathogenicity assays were conducted to determine the impact of Mt-clay, CPC and CPC-Mt complex on amoeba-mediated binding and host cell death. Furthermore, assays were also performed to determine inhibitory effects of Mt-clay, CPC and CPC-Mt complex on encystment and excystment. In addition, the cytotoxicity of Mt-clay, CPC and CPC-Mt complex against human cells was examined. RESULTS: The results revealed that CPC and CPC-Mt complex presented significant antiamoebic effects against A. castellanii at microgram dose. Also, the CPC and CPC-Mt complex inhibited amoebae binding to host cells. Furthermore, CPC and CPC-Mt complex, were found to inhibit the encystment and excystment processes. Finally, CPC and CPC-Mt complex showed minimal host cell cytotoxicity. These results show that CPC and CPC-Mt complex exhibit potent anti-acanthamoebic properties. CONCLUSION: Given the ease of usage, safety, cost-effectiveness and long-term stability, CPC and CPC-Mt complex can prove to be an excellent choice in the rational development of contact-lens disinfectants to eradicate pathogenic Acanthamoeba effectively.

Overnight orthokeratology-associated Acanthamoeba keratitis at a tertiary referral hospital in Taiwan: A retrospective case-control study.

BACKGROUND: Acanthamoeba keratitis (AK) is a vision-threatening disease, usually associated with contact lens (CL) wear. As overnight orthokeratology (OOK) is increasingly used to control myopia, we have found incidence of OOK-associated AK is increasing. This study aimed to investigate the clinical presentation and visual outcomes of OOK-associated AK. METHODS: Demographic characteristics, clinical features, and treatment outcomes were collected by reviewing the medical charts of CL-associated AK patients (n = 35) diagnosed at Taipei Veterans General Hospital from 2001 to 2016. Cases were OOK-associated AK patients (n = 13), and controls were all other CL-associated AK patients (n = 22). Student t tests and chi-square tests were used to compare cases and controls. Linear regression analyses were used to identify factors associated with the final visual outcome in CL-associated AK. RESULTS: OOK-associated AK accounted for half of all CL-associated AK after 2010. OOK-associated AK patients and other CL-associated patients had similar best-corrected logarithm of the minimum angle of resolution visual acuity (BCLVA) before treatment (1.10 ± 0.75 vs 1.13 ± 0.76, p = 0.893), but OOK-associated AK patients were younger (17.15 ± 3.21 vs 26.36 ± 12.81 years, p = 0.004), had less severe disease (ring infiltration, 0% vs 31.82%, p = 0.023), and had better post-treatment BCLVA (0.06 ± 0.15 vs 0.51 ± 0.95, p = 0.041). Multiple linear regression analysis showed that better BCLVA after treatment in CL-associated AK was associated with initial presentation without ring infiltration (p = 0.002) but not with OOK use itself (p = 0.793). Twenty-six of 35 CL-associated AK patients had final BCLVA equal to or better than 0.10 (Snellen visual acuity of 6/7.5). All 13 OOK-associated AK cases were treated with chlorhexidine 0.02% ± voriconazole 1% ± oral voriconazole, and 12 of these patients had final BCLVA equal to or better than 0.10. CONCLUSION: Most CL-associated AK patients had satisfactory visual outcomes. Half of AK at our hospital is OOK-associated since 2010. Early diagnosis and correct treatment may be the reason why OOK-associated AK patients had better vision prognosis.

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.

Anterior Scleral and Limbal Inflammatory Necrosis After Adjuvant Miltefosine for Recalcitrant Acanthamoeba Keratitis.

PURPOSE: The purpose of this study was to report a retrospective case series of anterior scleral and limbal inflammatory necrosis after adjuvant miltefosine for recalcitrant Acanthamoeba keratitis (AK). METHODS: A case series and literature review. RESULT: Four eyes of 3 patients with recalcitrant AK developed anterior scleral and limbal inflammatory necrosis with significant scleral-limbal thinning after treatment with miltefosine. The average age was 38 years, and the average duration of infection before miltefosine treatment was 239 days. All cases required urgent surgical intervention to either prevent or mitigate corneal-limbal perforation. CONCLUSIONS: Miltefosine has been observed to result in the resolution of AK when used as an adjunctive therapy. It may also lead to a consecutive inflammatory necrosis of the anterior sclera and limbus. This inflammatory response may be significant enough to cause rapid scleral-limbal thinning with subsequent perforation.

Incidence and Risk Factors of Ocular Hypertension and Glaucoma in Patients With Acanthamoeba Keratitis.

OBJECTIVES: To determine the incidence of ocular hypertension (OHT) and glaucoma in patients with acanthamoeba keratitis (AK) and to outline the risk factors for the development of glaucoma. METHODS: A retrospective review of patients diagnosed with AK at our institute during the period from 2000 to 2018. The main outcome measures were the incidence of OHT and glaucoma, and risk factors for the development of glaucoma. RESULTS: Fifty-two eyes diagnosed with AK were included. The incidence of OHT and glaucoma was 51.9% and 32.7%, respectively. The mean duration from disease onset to the first attack of elevated intraocular pressure was 8.4±16.6 months. The use of corticosteroids in the treatment regimen was significantly associated with the development of glaucoma (odds ratio, 3.93; 95% confidence interval, 0.96-16.15; P=0.049). At the last follow-up visit, both patients with glaucoma and nonglaucoma patients had improved visual acuity without a difference in the mean amount of logarithm of the minimum angle of resolution acuity improvement among them (0.56±0.91 vs. 0.67±0.87, P=0.686). CONCLUSION: Our findings confirm that OHT and glaucoma are frequent complications in AK. Patients treated with a regimen containing corticosteroids are at a higher risk; thus, they should receive close intraocular pressure monitoring.

Innate and Adaptive Gene Single Nucleotide Polymorphisms Associated With Susceptibility of Severe Inflammatory Complications in Acanthamoeba Keratitis.

Purpose: Over a third of patients with Acanthamoeba keratitis (AK) experience severe inflammatory complications (SICs). This study aimed to determine if some contact lens (CL) wearers with AK were predisposed to SICs due to variations in key immune genes. Methods: CL wearers with AK who attended Moorfields Eye Hospital were recruited prospectively between April 2013 and October 2014. SICs were defined as scleritis and/or stromal ring infiltrate. Genomic DNA was processed with an Illumina Low Input Custom Amplicon assay of 58 single nucleotide polymorphism (SNP) targets across 18 genes and tested for association in PLINK. Results: Genomic DNA was obtained and analyzed for 105 cases of AK, 40 (38%) of whom experienced SICs. SNPs in the CXCL8 gene encoding IL-8 was significantly associated with protection from SICs (chr4: rs1126647, odds ratio [OR] = 0.3, P = 0.005, rs2227543, OR = 0.4, P = 0.007, and rs2227307, OR = 0.4, P = 0.02) after adjusting for age, sex, steroids prediagnosis, and herpes simplex keratitis (HSK) misdiagnosis. Two TLR-4 SNPs were associated with increased risk of SICs (chr9: rs4986791 and rs4986790, both OR = 6.9, P = 0.01). Th-17 associated SNPs (chr1: IL-23R rs11209026, chr2: IL-1ß rs16944, and chr12: IL-22 rs1179251) were also associated with SICs. Conclusions: The current study identifies biologically relevant genetic variants in patients with AK with SICs; IL-8 is associated with a strong neutrophil response in the cornea in AK, TLR-4 is important in early AK disease, and Th-17 genes are associated with adaptive immune responses to AK in animal models. Genetic screening of patients with AK to predict severity is viable and this would be expected to assist disease management.

Orthokeratology lens-related Acanthamoeba keratitis: case report and analytical review.

Acanthamoeba keratitis (AK) is a rare but severe ocular infection with a significant risk of vision loss. Contact lens use is the main risk factor for AK. The orthokeratology (OK) lens, a specially designed contact lens, has been used worldwide as an effective method of myopia control. However, the OK lens is associated with an increased risk of Acanthamoeba infection. Many primary practitioners are concerned about this infection because of its relative rarity, the lack of promising therapeutic medications, and the need for referral. We herein report two cases of AK associated with OK lenses, present a systematic review of such cases, and discuss the possible reasons for the higher incidence rate of this infection in patients who wear OK lenses. We combined the clinical knowledge and skills of corneal specialists and lens experts with the sole objective of addressing these OK lens-related AK cases. We found that the most common risk factors were rinsing the lenses or lens cases with tap water. Prompt and accurate diagnosis along with adequate amoebicidal treatment are essential to ensure desirable outcomes for OK lens wearers who develop AK. Appropriate OK lens parameters and regular checkups are also important.

Endotheliitis-A Presentation of Acanthamoeba Keratitis.

PURPOSE: To report endotheliitis as an early, key presenting sign of Acanthamoeba keratitis in patients who are soft contact lens wearers. METHODS: We report 4 cases of patients presenting with pain, red eye, and reduction in vision in the context of soft contact lens wear. On examination, the predominant clinical finding was that of endotheliitis, localized fusiform stromal edema with corresponding keratic precipitates, anterior chamber inflammation, and minimal epithelial and anterior stromal signs. The classical signs of Acanthamoeba keratitis were not present. RESULTS: All 4 cases were clinically diagnosed as Acanthamoeba endotheliitis; corneal scrapes were negative; case 1 was polymerase chain reaction positive, and case 3 underwent confocal microscopy that showed double-walled cysts, suggesting Acanthamoeba. All responded well to anti-Acanthamoeba medication alone with 3 cases achieving complete resolution with minimal anterior stromal scarring by 7 weeks. Case 1 had steroid treatment before being seen at our unit and had a prolonged course of treatment with complete resolution by 4 months. CONCLUSIONS: It is imperative to have a high index of suspicion for Acanthamoeba in patients presenting with pain and endotheliitis in the context of contact lens wear, even in the absence of classical signs.

Acanthamoeba Keratitis in Minors With Orthokeratology (OK) Lens Use: A Case Series.

OBJECTIVES: Myopia progression is a significant public health issue. Methods to halt myopia progression in minors continue to gain momentum. Orthokeratology, with market penetrance estimates approximating 1%, is a corneal reshaping therapy and potential myopia progression treatment. Our objective was to explore whether orthokeratology may increase the frequency of Acanthamoeba keratitis compared with other lens modalities. METHODS: Individuals less than 18 years diagnosed with Acanthamoeba keratitis (AK) at the University of Illinois at Chicago (UIC) Cornea Service between January 1st, 2003, and December 31st, 2016, were retrospectively reviewed. Subjects were grouped by lens modality (soft, rigid gas permeable [RGP], and orthokeratology), and all cases with orthokeratology lens use were reviewed. The primary outcome was a history of orthokeratology lens use in minors diagnosed with AK. RESULTS: Forty-seven contact lens users less than 18 years were diagnosed with AK. The mean age was 15.0 years (range 12-17), 26 (55%) were women, and 4 (8.5%) had bilateral disease. Lens modality included 6 (13%) with orthokeratology, 39 (83%) with soft contact lenses, 0 with nonorthokeratology RGP (0%), and 2 (4%) unknown. CONCLUSIONS: The proportion of orthokeratology cases among AK minors (13%) in our case series exceeds the expected proportion of orthokeratology cases expected based on orthokeratology market penetrance (1%). Results from this case series suggest a potential increased risk of AK in orthokeratology users compared with other lens modalities. In the context of the current myopia epidemic and concerns for halting myopia progression in minors, caution should be exercised when selecting appropriate treatment options to minimize the risk of AK.

[Necrotizing scleritis after acanthamoeba keratitis]. / Nekrotisierende Skleritis nach Akanthamöbenkeratitis.

Nodular scleritis and necrotizing scleritis are rare complications of acanthamoeba keratitis. This article presents the case of a 61-year-old female patient who had suffered from persistent keratitis in the right eye for more than 4 months. The patient was initially treated with propamidine isethionate and polyhexamethylene biguanide eye drops. A penetrating limbo-keratoplasty was performed. Examination of the corneal explant showed acanthamoeba cysts. In the following 5 months the sclera showed recurrent abscesses. A total of two thermal cauterizations and three amniotic membrane grafts were carried out. To our knowledge, this is the first case of sclerokeratitis after acanthamoeba keratitis which was treated with a combination of thermal cauterization and amniotic membrane transplantation. Further studies are necessary to investigate this procedure as an alternative to the established cryotherapy.

Systemic Miltefosine as an Adjunct Treatment of Progressive Acanthamoeba Keratitis.

Purpose: To report our experience with oral miltefosine (MLT) as an adjunct treatment for progressive Acanthamoeba keratitis (AK).Methods: Retrospective case series of all patients who underwent treatment with oral MLT for AK at Bascom Palmer Eye Institute from 2017 to 2020.Results: Six females from 16 to 55 years old, with a microbiologic diagnosis of Acanthamoeba, were treated with MLT and standard medical treatment. Four of the six cases deteriorated after initiating treatment and three required a therapeutic keratoplasty. Two patients improved after 1 week of MLT and optical penetrating keratoplasty was performed after clinical resolution. Microbiologic culture of corneal buttons was negative in all cases. All corneal grafts remain clear at last follow-up with best-corrected visual acuity of 20/40 or better.Conclusion: Oral MLT may be a viable adjunctive therapy for recalcitrant AK; however, its use may be associated with a severe inflammatory reaction. Further studies are needed to evaluate its efficacy and variable clinical response.

A 5-Year Review of Acanthamoeba Keratitis Related to Wearing Contact Lenses in Korea.

PURPOSE: To investigate the presentation, clinical characteristics, and outcomes of Acanthamoeba keratitis (AK) in Busan, South Korea, over a 5-year period. METHODS: This retrospective study involved a review of the medical records of 16 patients (19 eyes in total) who were diagnosed with AK, related to wearing contact lenses, at the tertiary hospital, Pusan National University Hospital at Busan City, from December 2013 to December 2018. RESULTS: Nineteen eyes of 16 patients with a diagnosis of AK were identified. The average age of the patients was 21.1±12.6 years; there were 2 men and 14 women. The mean period from the onset of the first symptoms to diagnosis was 7.0±6.5 days. The average initial visual acuity was 0.78±0.37 (tested on a logarithm of the minimum angle of resolution chart), and the final visual acuity after treatment was 0.07±0.07, indicating a significant improvement (P=0.001). A variety of corneal lesions were identified. Early diagnosis of AK was associated with a significantly better final visual acuity. CONCLUSION: The average therapeutic period for AK, when a surface epithelial lesion of the cornea was identified, was 4 months compared with an average period of over 6 months for a deeper stromal lesion. Therefore, this study highlights the fundamental importance of early diagnosis, preventing deeper layers of the cornea from being affected, and appropriate management to ensure a favorable outcome.

Detección de Acanthamoeba por reacción en cadena de la polimerasa en tiempo real en líquidos de conservación de lentes de contacto / Detection of Acanthamoeba sp. by real-time polymerase chain reaction in contact lens solutions

RESUMEN Objetivo: Estandarizar una técnica de reacción en cadena de la polimerasa en tiempo real para la detección del parásito e identificar Acanthamoeba en líquidos conservantes de lentes de contacto. Métodos: Se realizó un estudio descriptivo observacional de corte transversal sobre la técnica de reacción en cadena de la polimerasa en tiempo real para la detección de Acanthamoeba, en el Instituto de Investigaciones en Ciencias de la Salud de la ciudad de Asunción, en Paraguay. Se analizaron 110 líquidos conservantes aportados por usuarios sanos de lentes de contacto, mediante reacción en cadena de la polimerasa en tiempo real y cultivo en medio PAGE - SDS. Resultados: Se estandarizó con éxito la técnica de reacción en cadena de la polimerasa en tiempo real con límite de sensibilidad de 1 pg/µL. Se aisló Acanthamoeba a partir de una muestra (1 por ciento) por método de cultivo, mientras que la carga parasitaria en el líquido conservante fue inferior al límite de detección de la reacción en cadena de la polimerasa en tiempo real. El ADN obtenido del cultivo de dicha muestra fue positivo para Acanthamoeba por este método. Conclusión: El sistema estandarizado presenta buena sensibilidad y podrá ser incorporado en los laboratorios que cuentan con acceso a equipos de reacción en cadena de la polimerasa en tiempo real para un diagnóstico rápido y más eficiente en casos de sospechas de queratitis amebiana. Recomendamos el uso combinado de métodos moleculares y cultivo para aumentar la potencia del diagnóstico, sobre todo en muestras donde la carga parasitaria es muy baja(AU)

ABSTRACT Objective: Standardize a real-time polymerase chain reaction technique for detection of the parasite and identify Acanthamoeba in contact lens solutions. Methods: A cross-sectional observational descriptive study was conducted about a real-time polymerase chain reaction technique for detection of Acanthamoeba at the Institute of Health Sciences Research in the city of Asunción, Paraguay. A total 110 solutions were analyzed, which were provided by healthy contact lens users, by real-time polymerase chain reaction and culture in SDS-PAGE medium. Results: Successful standardization was achieved of the real-time polymerase chain reaction technique with a sensitivity limit of 1 pg/µl. Acanthamoeba was isolated from one sample (1 percent) by culture, whereas the parasite load in the contact lens solution was below the detection limit of the real-time polymerase chain reaction technique. The DNA obtained from the culture of that sample was positive for Acanthamoeba by the real-time polymerase chain reaction technique method. Conclusion: The system standardized exhibits good sensitivity and may be incorporated into laboratories with real-time polymerase chain reaction technique equipment for a rapid and more efficient diagnosis of suspected amoebic keratitis. We recommend the combined use of molecular methods and culture to enhance diagnostic power, mainly in samples where the parasite load is very low(AU)

The First Acanthamoeba keratitis Case of Non-Contact Lens Wearer with HIV Infection in Thailand.

Acanthamoeba keratitis (AK) is a rare sight-threatening corneal infection, often reporting from contact lens wearers. An asymptomatic human immunodeficiency virus (HIV)-infected Thai male without history of contact lens use complained foreign body sensation at his left eye during motorbike riding. He had neither specific keratitis symptoms nor common drugs responding, which contributed to delayed diagnosis. By corneal re-scraping, Acanthamoeba-like cysts were detected by calcofluor white staining and agar culture. The etiological agent obtained from the culture was molecularly confirmed by Acanthamoeba spp.-specific PCR, followed by DNA sequencing. The results from BLAST and phylogenetic analysis based on the DNA sequences, revealed that the pathogen was Acanthamoeba T4, the major genotype most frequently reported from clinical isolates. The infection was successfully treated with polyhexamethylene biguanide resulting in corneal scar. This appears the first reported AK case from a non-contact lens wearer with HIV infection in Thailand. Although AK is sporadic in developing countries, a role of free-living Acanthamoeba as an opportunistic pathogen should not be neglected. The report would increase awareness of AK, especially in the case presenting unspecific keratitis symptoms without clinical response to empirical antimicrobial therapy.