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Review
. 2015;22:10.
doi: 10.1051/parasite/2015010. Epub 2015 Feb 18.

An Update on Acanthamoeba Keratitis: Diagnosis, Pathogenesis and Treatment

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Free PMC article
Review

An Update on Acanthamoeba Keratitis: Diagnosis, Pathogenesis and Treatment

Jacob Lorenzo-Morales et al. Parasite. .
Free PMC article

Abstract

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.

Les amibes à vie libre du genre Acanthamoeba sont les agents causant une infection sévère de la cornée, dangereuse pour la vue, appelée kératite à Acanthamoeba. De plus, le nombre de cas signalés à travers le monde est en augmentation année après année, principalement chez les porteurs de lentilles de contact, bien que des cas de kératite à Acanthamoeba aient également été signalés chez les non-porteurs de lentilles. Fait intéressant, la kératite à Acanthamoeba est restée significative, en dépit de nos progrès dans la chimiothérapie antimicrobienne et les soins de soutien. En partie, cela est dû à une compréhension incomplète de la pathogenèse et la physiopathologie de la maladie, aux retards du diagnostic et aux problèmes associés aux interventions chimiothérapeutiques. Compte tenu de la nature dévastatrice de cette maladie, nous présentons ici notre compréhension actuelle de la kératite à Acanthamoeba et des mécanismes moléculaires associés à la maladie, ainsi que les traits de virulence de Acanthamoeba qui peuvent être des cibles potentielles pour l’amélioration du diagnostic, les interventions thérapeutiques et/ou pour l’élaboration de mesures préventives. Des approches moléculaires comme la protéomique, l’ARNi et des approches consensuelles de diagnostic pour un cas suspecté de kératite à Acanthamoeba sont proposées et examinées sur la base des données qui ont été compilées après des années de travail sur cet organisme amibien, utilisant de nombreuses techniques différentes et l’écoute de nombreux experts sur ce domaine à des conférences, ateliers et réunions internationales. Au total, cette étude peut servir de jalon pour développer une solution efficace pour la prévention, le contrôle et le traitement des infections à Acanthamoeba.

Figures

Figure 1.
Figure 1.
(A) Corneal melting and vascularization in a patient with Acanthamoeba keratitis. (B) Observed corneal damage in AK is shown after sodium fluorescein application. Original.
Figure 1.
Figure 1.
(A) Corneal melting and vascularization in a patient with Acanthamoeba keratitis. (B) Observed corneal damage in AK is shown after sodium fluorescein application. Original.
Figure 2.
Figure 2.
Overview of the diagnostic procedure for Acanthamoeba keratitis.
Figure 2.
Figure 2.
Overview of the diagnostic procedure for Acanthamoeba keratitis.
Figure 3.
Figure 3.
Acanthamoeba trophozoites with the characteristic acanthopodia (A) in phase contrast, (B) in bright field microscopy. Scale bar: 10 μm. Originals.
Figure 3.
Figure 3.
Acanthamoeba trophozoites with the characteristic acanthopodia (A) in phase contrast, (B) in bright field microscopy. Scale bar: 10 μm. Originals.
Figure 4.
Figure 4.
Acanthamoeba cysts in interference contrast microscopy (A) morphological group I, (B) morphological group II, (C) morphological group III. Scale bar: 10 μm. Original.
Figure 4.
Figure 4.
Acanthamoeba cysts in interference contrast microscopy (A) morphological group I, (B) morphological group II, (C) morphological group III. Scale bar: 10 μm. Original.
Figure 5.
Figure 5.
Acanthamoeba trophozoites observed in culture in a case of severe AK infection.
Figure 5.
Figure 5.
Acanthamoeba trophozoites observed in culture in a case of severe AK infection.
Figure 6.
Figure 6.
Factors contributing to the pathogenicity of Acanthamoeba.
Figure 6.
Figure 6.
Factors contributing to the pathogenicity of Acanthamoeba.
Figure 7.
Figure 7.
Schematics of Acanthamoeba-mediated corneal damage. “Blast” refers to damage.
Figure 7.
Figure 7.
Schematics of Acanthamoeba-mediated corneal damage. “Blast” refers to damage.
Figure 8.
Figure 8.
Acanthamoeba-mediated corneal epithelial cell death.
Figure 8.
Figure 8.
Acanthamoeba-mediated corneal epithelial cell death.

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