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Parasite (Paris, France) 2015Free-living amoebae of the genus Acanthamoeba are causal agents of a severe sight-threatening infection of the cornea known as Acanthamoeba keratitis. Moreover, the... (Review)
Review
Free-living amoebae of the genus Acanthamoeba are causal agents of a severe sight-threatening infection of the cornea known as Acanthamoeba keratitis. Moreover, the number of reported cases worldwide is increasing year after year, mostly in contact lens wearers, although cases have also been reported in non-contact lens wearers. Interestingly, Acanthamoeba keratitis has remained significant, despite our advances in antimicrobial chemotherapy and supportive care. In part, this is due to an incomplete understanding of the pathogenesis and pathophysiology of the disease, diagnostic delays and problems associated with chemotherapeutic interventions. In view of the devastating nature of this disease, here we present our current understanding of Acanthamoeba keratitis and molecular mechanisms associated with the disease, as well as virulence traits of Acanthamoeba that may be potential targets for improved diagnosis, therapeutic interventions and/or for the development of preventative measures. Novel molecular approaches such as proteomics, RNAi and a consensus in the diagnostic approaches for a suspected case of Acanthamoeba keratitis are proposed and reviewed based on data which have been compiled after years of working on this amoebic organism using many different techniques and listening to many experts in this field at conferences, workshops and international meetings. Altogether, this review may serve as the milestone for developing an effective solution for the prevention, control and treatment of Acanthamoeba infections.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Adrenal Cortex Hormones; Amebicides; Animals; Biological Assay; Chlorhexidine; Corneal Transplantation; Cross-Linking Reagents; Diagnostic Techniques, Ophthalmological; Host-Parasite Interactions; Humans; Hydroxymercuribenzoates; Mice; Parasitology; Phagocytosis; Protozoan Proteins; Specimen Handling; Virulence
PubMed: 25687209
DOI: 10.1051/parasite/2015010 -
The CLAO Journal : Official Publication... Jan 1995The incidence of Acanthamoeba keratitis has decreased significantly, and it is no longer a reportable condition in the United States. Corneal abrasion and contact lenses... (Review)
Review
The incidence of Acanthamoeba keratitis has decreased significantly, and it is no longer a reportable condition in the United States. Corneal abrasion and contact lenses play an important role in the development of Acanthamoeba keratitis. One of the most important features of the disease is severe pain, which is atypical for herpes simplex. The pathognomonic sign for Acanthamoeba is radial neuritis or inflammation around the corneal nerve caused by the parasites. The most important step in prevention of Acanthamoeba keratitis is effective education of patients about the care of contact lenses. A combination of Brolene and Neomycin is the best approach in treating Acanthamoeba keratitis. However, if treatment with these drugs fails, clotrimazole is recommended.
Topics: Acanthamoeba Keratitis; Animals; Contact Lenses; Humans
PubMed: 7712613
DOI: No ID Found -
Ophthalmic & Physiological Optics : the... Jan 2021Acanthamoeba keratitis is an infection caused by a unicellular protozoan of the genus Acanthamoeba that is universally widespread. Until now, most cases were reported in... (Review)
Review
UNLABELLED
Acanthamoeba keratitis is an infection caused by a unicellular protozoan of the genus Acanthamoeba that is universally widespread. Until now, most cases were reported in contact lens wearers, although it is also a reality for non-wearers, mostly connected to corneal trauma. There is also a variation in incidence regarding the aetiology of the disease between developed and developing countries.
PURPOSE
This work is based on a literature review, and the main goal is to deepen the knowledge about Acanthamoeba keratitis, presenting the main risk factors and focusing on prevention actions for this type of corneal infection since the treatments are not always effective. It targets specialists in visual health to strengthen their knowledge in this area, as well as to allow them to better inform their patients about hygiene care, appropriate measures of disinfection and ways to minimise the risk of infection. At this stage, it is important to highlight the essential role that practitioners play in fitting, monitoring and following-up patients to minimise the danger of infection.
RECENT FINDINGS
It is well recognised that corneal trauma facilitates invasion by leaving an open door for microorganisms to penetrate the cornea. In addition to trauma, risk factors are mostly associated with patients' behaviours, such as interaction of contact lenses with contaminated water in the shower, swimming pools and beaches, etc., lack of hygiene habits with contact lenses and respective cases, and the use of ineffective disinfecting solutions. The fact that a disinfecting solution is not completely effective against trophozoites and/or cysts, both forms of Acanthamoeba's lifecycle, can cause the infection since one cyst alone leads to the emergence of a whole new population of Acanthamoeba.
SUMMARY
It is necessary to reduce the risk of infection and, beyond the need to promote patient education to encourage correct CL hygiene behaviours, it should also be highlighted that there is an urgent need to enhance the efficacy of CL disinfection systems against all strains and both stages of Acanthamoeba through the creation of standardised methods. The ease of purchasing CLs without any supervision must also be considered a concern, and, in the near future, it is also important to develop and implement effective diagnostic methods and treatments for Acanthamoeba keratitis.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Humans; Incidence; Risk Factors
PubMed: 33119189
DOI: 10.1111/opo.12752 -
The Ocular Surface Jul 2022Acanthamoeba keratitis (AK) is a severe cause of infectious keratitis and represents a significant clinical challenge. Recent literature regarding AK epidemiology,... (Review)
Review
Acanthamoeba keratitis (AK) is a severe cause of infectious keratitis and represents a significant clinical challenge. Recent literature regarding AK epidemiology, diagnosis, treatment modalities, and prognosis is reviewed and synthesized to propose an algorithmic protocol for AK management. Globally, AK outbreaks in developed countries are ongoing, and AK rates have increased. Moreover, current outbreaks may carry a worse prognosis than prior outbreaks. Despite identification of contact lens solutions implicated in AK outbreaks and the consequent market recall of these products, outbreaks persist. Acanthamoeba keratitis afflicts not only refractive soft contact lens users but also cosmetic contact lens users and gas permeable (especially orthokeratology) lens users. Innovations in in vivo confocal microscopy and PCR assays have increased the role for these adjuvant tests alongside corneal smear and culture in a multimodal diagnostic approach to suspected AK. Biguanides (such as chlorhexidine and polyhexamethylene biguanide) and diamidines (propamidine isethionate and hexamidine) remain cornerstones of AK management, and evidence for other treatment modalities continues to evolve. Voriconazole in topical and systemic forms may be useful as adjuvant therapy. The anti-leishmaniasis drug miltefosine, recently given orphan drug status by the United States Food and Drug Administration, has increasing evidence supporting a role in patients with severe/refractory disease. Prior topical corticosteroids have been consistently shown to be associated with worse outcomes in AK. Although not historically thought of as a treatment modality, benzalkonium chloride preservative may be leveraged for its anti-Acanthamoebal properties. The role of Rose-Bengal photodynamic antimicrobial therapy is evolving in selected cases of AK.
Topics: Acanthamoeba Keratitis; Contact Lenses; Cornea; Humans; Photochemotherapy; Prognosis
PubMed: 35462076
DOI: 10.1016/j.jtos.2022.04.003 -
Journal Francais D'ophtalmologie Oct 2014Early diagnosis and appropriate therapy are key elements for a good prognosis in Acanthamoeba keratitis (AK). AK should be considered in any case of corneal trauma... (Review)
Review
Early diagnosis and appropriate therapy are key elements for a good prognosis in Acanthamoeba keratitis (AK). AK should be considered in any case of corneal trauma complicated by exposure to soil or contaminated water, and in all contact lens (CL) wearers. A presumptive diagnosis of AK can be made clinically and with in vivo confocal microscopy, although a definitive diagnosis requires identification of Acanthamoeba on direct scraping, histology, or identification of Acanthamoeba DNA by polymerase chain reaction (PCR). We use cysticidal drugs for treating AK because encysted forms are more resistant than trophozoites to treatment. The treatment protocol used a biguanide (PHMB 0.02% or chlorhexidine 0.02%) and a diamidine (propamidine 0.1% or hexamidine 0.1%). New diagnostic modalities and more specific topical anti-amoebic treatments would substantially benefit patients with AK.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Adrenal Cortex Hormones; Amebicides; Animals; Biguanides; Cataract; Contact Lenses; Corneal Stroma; Corneal Surgery, Laser; Corneal Transplantation; Corneal Ulcer; Debridement; Glaucoma; Humans; Life Cycle Stages; Microscopy, Confocal; Photochemotherapy; Postoperative Complications; Prognosis; Riboflavin; Soil; Ultraviolet Rays
PubMed: 25169145
DOI: 10.1016/j.jfo.2014.05.004 -
The Israel Medical Association Journal... Apr 2013
Review
Topics: Acanthamoeba; Acanthamoeba Keratitis; Antiprotozoal Agents; Contact Lenses; Cornea; Humans; Incidence
PubMed: 23781754
DOI: No ID Found -
The New England Journal of Medicine Jul 2019
Topics: Acanthamoeba; Acanthamoeba Keratitis; Adult; Cornea; Female; Humans
PubMed: 31314971
DOI: 10.1056/NEJMicm1817678 -
Current Medicinal Chemistry 2019First discovered in the early 1970s, Acanthamoeba keratitis has remained a major eye infection and presents a significant threat to the public health, especially in... (Review)
Review
BACKGROUND
First discovered in the early 1970s, Acanthamoeba keratitis has remained a major eye infection and presents a significant threat to the public health, especially in developing countries. The aim is to present a timely review of our current understanding of the advances made in this field in a comprehensible manner and includes novel concepts and provides clear directions for immediate research priorities.
METHODS
We undertook a search of bibliographic databases for peer-reviewed research literature and also summarized our published results in this field.
RESULTS
The present review focuses on novel diagnostic and therapeutic strategies in details which can provide access to management and treatment of Acanthamoeba keratitis. This coupled with the recently available genome sequence information together with high throughput genomics technology and innovative approaches should stimulate interest in the rational design of preventative and therapeutic measures. Current treatment of Acanthamoeba keratitis is problematic and often leads to infection recurrence. Better understanding of diagnosis, pathogenesis, pathophysiology and therapeutic regimens, would lead to novel strategies in treatment and prophylaxis.
Topics: Acanthamoeba Keratitis; Animals; Anti-Inflammatory Agents; Humans
PubMed: 29745319
DOI: 10.2174/0929867325666180510125633 -
Parasitology Research Sep 2021Acanthamoeba spp. are among the most worldwide prevalent protozoa. It is the causative agent of a disease known as Acanthamoeba keratitis, a painful and severe... (Review)
Review
Acanthamoeba spp. are among the most worldwide prevalent protozoa. It is the causative agent of a disease known as Acanthamoeba keratitis, a painful and severe sight-threatening corneal infection that can lead to blindness. In recent years, the prevalence of Acanthamoeba keratitis has rapidly increased, growing its importance to human health. This systematic review aims to assess the distribution of Acanthamoeba sp. genotypes causing keratitis around the world, considering the sample collected type and the used identification method. Most of the cases were found in Asia and Europe. Not surprisingly, the T4 genotype was the most prevalent worldwide, followed by T3, T15, T11, and T5. Furthermore, the T4 genotype contains a higher number of species. Given the differences in pathology, susceptibility to treatment, and clinical outcome between distinct genotypes, it is essential to genotype isolates from Acanthamoeba keratitis cases to help to establish a better correlation between in vitro and in vivo activities, resulting in better drug therapies and successful treatment in cases of this important ocular infection.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Cornea; Genotype; Humans
PubMed: 34351492
DOI: 10.1007/s00436-021-07261-1 -
Indian Journal of Ophthalmology Apr 2024This is a comprehensive review after a thorough literature search in PubMed-indexed journals, incorporating current information on the pathophysiology, clinical... (Review)
Review
This is a comprehensive review after a thorough literature search in PubMed-indexed journals, incorporating current information on the pathophysiology, clinical features, diagnosis, medical and surgical therapy, as well as outcomes of Acanthamoeba keratitis (AK). AK is a significant cause of ocular morbidity, and early diagnosis with timely institution of appropriate therapy is the key to obtaining good outcomes. The varied presentations result in frequent misdiagnosis, and co-infections can increase the morbidity of the disease. The first line of therapy continues to be biguanides and diamidines, with surgery as a last resort.
Topics: Humans; Acanthamoeba Keratitis; Pentamidine; Biguanides
PubMed: 38454853
DOI: 10.4103/IJO.IJO_2627_23