Acanthamoeba keratitis in Australia: demographics, associated factors, presentation and outcomes: a 15-year case review

Hӧllhumer, Roland; Keay, Lisa; Watson, Stephanie

doi:10.1038/s41433-019-0589-6

Cited by 29 publications

(37 citation statements)

References 27 publications

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“…are free-living protozoa widely spread in the environment that can cause infections in humans as facultative pathogens. They are associated with a severe eye infection, Acanthamoeba keratitis (AK), that usually affects contact lens wearers [ 1 ]. Furthermore, the presence of these organisms in water may represent a risk for immunocompromised individuals because of their pathogenicity and ability to act as a vector for viruses and pathogenic bacteria [ 2 ].…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural Study of Acanthamoeba polyphaga Trophozoites and Cysts Treated In Vitro with Cationic Carbosilane Dendrimers

et al. 2020

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Cationic carbosilane dendrimers are branched molecules with antimicrobial properties. Their activity has been tested against Acanthamoeba polyphaga, a causative agent of Acanthamoeba keratitis, a severe ocular disease in humans. A. polyphaga trophozoites and cysts were exposed to different noncytotoxic cationic carbosilane dendrimers with proven antiamoebic activity. The effects of treatment on cell surface and cell ultrastructure were examined by scanning and transmission electron microscopy, respectively. Two of the dendrimers tested induced dramatic alterations of cellular ultrastructure in both trophozoites and cysts, including vacuolization, depletion of cytoplasmic contents, and reduced cell size. Additionally, we observed severe alterations of the plasma membrane with membrane blebbing in trophozoites and disruption in cysts. These alterations were also observed with chlorhexidine, a drug used for treatment of Acanthamoeba keratitis. Our results support that these compounds may target membranes, and their action is critical for parasite integrity.

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Section: Introductionmentioning

confidence: 99%

Ultrastructural Study of Acanthamoeba polyphaga Trophozoites and Cysts Treated In Vitro with Cationic Carbosilane Dendrimers

et al. 2020

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“… 1 , 2 , 3 , 4 , 5 Progression of the infection can lead to a white stromal ring infiltrate, radial keratoneuritis, corneal ulceration, and anterior uveitis with or without hypopyon. 3 , 4 , 5 , 18 , 19 In the early stages of the disease, the clinical findings in acanthamoeba keratitis are non-specific, and lead to misdiagnosis. It has been reported that cases of early acanthamoeba infections are misattributed to herpetic keratitis 47.6% of the time, or, less commonly, mycotic (25.2%) or bacterial keratitis (3.9%).…”

Section: Introductionmentioning

confidence: 99%

Atypical presentation of acanthamoeba keratitis resembling central toxic keratopathy

Ward¹,

Hastings

Shmunes³

et al. 2022

American Journal of Ophthalmology Case Reports

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Purpose To describe an atypical case of acanthamoeba keratitis with positive in vivo confocal microscopy in a non-contact lens user who presented with signs and symptoms suggestive of central toxic keratopathy. Observations The patient presented with bilateral, though sequential, decreased visual acuity with mild pain. Examination showed stromal haze with corneal flattening and thinning without epithelial defects. Optical coherence tonometry of the right eye revealed an inverse dome-shaped appearance of the opacity and in-vivo confocal imaging showed double-walled cysts consistent with acanthamoeba. Corneal haze, stromal loss, resolved and visual acuity improved over time. Conclusion and importance Acanthamoeba is a rare cause of infectious keratitis that is most often associated with contact lens wear in developed countries. Typically, it presents with a unilateral decrease in visual acuity, photophobia, watering, and pain that is out of proportion to slit lamp examination findings. However, many atypical presentations have been reported in the literature. Consequently, it may be misdiagnosed, especially early in the course of the disease. This delay in diagnosis can lead to progressive ulceration and visual impairment. In addition, cyst formation can make eradication with anti-amoebic treatment especially difficult. Central toxic keratopathy is a non-inflammatory clinical syndrome of unknown etiology that is most often associated with excimer laser ablation, though other associated causes have been reported. It is characterized by a central or paracentral opacity with corneal stromal loss and resultant hyperopic shift. The opacification and stromal loss mostly resolve over the course of months with an improvement in visual acuity. This report may help physicians broaden their differential and correctly diagnose atypical presentations of amoebic infection.

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“…They have an active trophozoite form, approximately 15–35 μm in size with specialized pseudopodia and no descript shape, and a dormant cyst stage, approximately 10–20 μm in size, encased in a double-cellulose cell wall that provides increased protection from environmental stressors ( Khan, 2006 ; Garajová et al, 2019 ). Globally, increasing cases of Acanthamoeba -associated infections have been documented, prompting significant concerns from a clinical perspective ( Carnt et al, 2018 ; Randag et al, 2019 ; Scruggs et al, 2019 ; Höllhumer et al, 2020 ). These amoebae can be viewed as opportunistic parasites, ordinarily free living yet capable of causing severe infections under suitable circumstances.…”

Section: Introductionmentioning

confidence: 99%

Paradigms of Protist/Bacteria Symbioses Affecting Human Health: Acanthamoeba species and Trichomonas vaginalis

et al. 2021

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Ever since the publication of the seminal paper by Lynn Margulis in 1967 proposing the theory of the endosymbiotic origin of organelles, the study of the symbiotic relationships between unicellular eukaryotes and prokaryotes has received ever-growing attention by microbiologists and evolutionists alike. While the evolutionary significance of the endosymbiotic associations within protists has emerged and is intensively studied, the impact of these relationships on human health has been seldom taken into account. Microbial endosymbioses involving human eukaryotic pathogens are not common, and the sexually transmitted obligate parasite Trichomonas vaginalis and the free-living opportunistic pathogen Acanthamoeba represent two unique cases in this regard, to date. The reasons of this peculiarity for T. vaginalis and Acanthamoeba may be due to their lifestyles, characterized by bacteria-rich environments. However, this characteristic does not fully explain the reason why no bacterial endosymbiont has yet been detected in unicellular eukaryotic human pathogens other than in T. vaginalis and Acanthamoeba, albeit sparse and poorly investigated examples of morphological identification of bacteria-like microorganisms associated with Giardia and Entamoeba were reported in the past. In this review article we will present the body of experimental evidences revealing the profound effects of these examples of protist/bacteria symbiosis on the pathogenesis of the microbial species involved, and ultimately their impact on human health.

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Acanthamoeba keratitis in Australia: demographics, associated factors, presentation and outcomes: a 15-year case review

Abstract: Purpose To report the demographics, frequency of potential predisposing factors, presentation and outcomes of Acanthamoeba keratitis (AK) at a quaternary eye hospital in Sydney, Australia over a 15-year period.

Cited by 29 publications

References 27 publications

Ultrastructural Study of Acanthamoeba polyphaga Trophozoites and Cysts Treated In Vitro with Cationic Carbosilane Dendrimers

Ultrastructural Study of Acanthamoeba polyphaga Trophozoites and Cysts Treated In Vitro with Cationic Carbosilane Dendrimers

Atypical presentation of acanthamoeba keratitis resembling central toxic keratopathy

Paradigms of Protist/Bacteria Symbioses Affecting Human Health: Acanthamoeba species and Trichomonas vaginalis

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