World Library  
Flag as Inappropriate
Email this Article

Acanthamoeba keratitis

Article Id: WHEBN0005179331
Reproduction Date:

Title: Acanthamoeba keratitis  
Author: World Heritage Encyclopedia
Language: English
Subject: Keratitis, Amoebozoa, List of MeSH codes (C03), Corneal ulcer, Amoebiasis
Collection: Amoebozoa, Disorders of Sclera and Cornea, Rare Diseases, Rare Infectious Diseases
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Acanthamoeba keratitis

Acanthamoeba keratitis
Eye with Acanthamoeba keratitis
(fluorescein observation)
Classification and external resources
eMedicine med/10
MeSH D015823

Acanthamoeba keratitis is a rare disease in which amoebae invade the cornea of the eye. It may result in permanent visual impairment or blindness.[1][2][3]

Contents

  • Life Cycle 1
  • Causes 2
  • Diagnosis 3
  • Prevalence 4
  • Prevention 5
  • Treatment 6
  • References 7
  • External links 8

Life Cycle

Species within the genus Acanthamoeba are generally free-living trophozoites. These trophozoites are relatively ubiquitous and can live in, but are not restricted to, tap water, freshwater lakes/rivers and soil. [4] Besides the trophozoite stage, a cyst stage may also be present. Both of these stages are usually uninucleated and reproduce by the means of binary fission. When the environment poses conditions that are not favorable, the trophozoites encyst to produce double-walled cysts. [5] A picture reference of the life cycle may be viewed here.

Acanthamoeba trophozoite. Scale bar: 10 μm

Causes

In the United States, it is nearly always associated with contact lens use, as Acanthamoeba can survive in the space between the lens and the eye.[6][7][8][9] For this reason, contact lenses must be properly disinfected before wearing, and should be removed when swimming or surfing.

However, elsewhere in the world, there have been many cases of Acanthamoeba in those who don't wear contact lenses.[10][11]

Diagnosis

To detect Acanthamoeba on a contact lens in a laboratory, the contact lens is placed on a non-nutrient agar saline plate seeded with a gram-negative bacteria such as E. coli. If Acanthamoeba are present, they will reproduce readily and become visible on the plate under 10-20X objective on an inverted microscope. Polymerase chain reaction can also be used to confirm a diagnosis of Acanthamoeba keratitis, especially when contact lenses are not involved. Acanthameoba is also characterized by a brawny edema and hazy view into the anterior chamber. Late stages of the disease also produces a ring shaped corneal ulcer.[12] Signs and symptoms include severe pain, severe keratitis (similar to stromal herpetic disease), corneal perineuritis, and ring ulcer (late in the disease process). [13]

Prevalence

A recently published study was conducted by an institution in Austria. The goal was to diagnose Acanthamoeba keratitis to give an overview of proven cases of Acanthamoeba infections in Austria during the past 20 years. Samples of patients suspected to have Acanthamoeba keratitis were screened by using gram negative bacteria cultures and/or PCR and the detected amoebae were genotyped. Over the course of the testing, a total of 154 cases of Acanthamoeba keratitis were diagnosed. The age of the positive tests ranged from 8 to 82 years old and 58% of the patients were female. More importantly, the data showed that 89% of the infected patients were contact lens wearers and 19% of the patients required a corneal transplant. [14]

Prevention

According to the American Optometric Association, the following steps can be taken to prevent Acanthamoeba keratitis:

• Always wash hands before handling contact lenses.

• Rub and rinse the surface of the contact lens before storing.

• Use only sterile products recommended by your optometrist to clean and disinfect your lenses. Saline solution and rewetting drops are not designed to disinfect lenses.

• Avoid using tap water to wash or store contact lenses.

• Contact lens solution must be discarded upon opening the case, and fresh solution used each time the lens is placed in the case.

• Replace lenses using your doctor’s prescribed schedule.

• Do not sleep in contact lenses unless prescribed by your doctor and never after swimming.

• Never swap lenses with someone else.

• Never put contact lenses in your mouth.

• See your optometrist regularly for contact lens evaluation. [15]

Treatment

One treatment used is Polyhexamethylene biguanide, PHMB.[16]

Propamidine isethionate has also shown some effectiveness.[17]

Another possible agent is chlorhexidine.[18]

Keratoplasty may sometimes be required.[17]

A combined regimen of propamidine, miconazole nitrate, and neomycin has also been suggested.[19][20]

References

  1. ^ Lorenzo-Morales, Jacob; Khan, Naveed A.; Walochnik, Julia (2015). keratitis: diagnosis, pathogenesis and treatment"Acanthamoeba"An update on . Parasite 22: 10.  
  2. ^ Anna Hodgekiss (2012-08-20). "I swam with my contact lenses in - now I'm blind in one eye | Mail Online". Dailymail.co.uk. Retrieved 2013-08-02. 
  3. ^ "CDC - Acanthamoeba Infection - General Information - Acanthamoeba Keratitis FAQs". Cdc.gov. Retrieved 2013-08-02. 
  4. ^ "Acanthamoeba-General Information-Acanthamoeba keratitis". CDC. 
  5. ^ "Free-living Amebic Infections". CDC. 
  6. ^ Auran, JD; Starr MB; Jakobiec FA (1987). "Acanthamoeba keratitis. A review of the literature". Cornea 6 (1): 2–26.  
  7. ^ JOHN D.T. (1993) Opportunistically pathogenic free-living amebae. In: J.P. Kreier and J.R. Baker (Eds.), Parasitic Protozoa. Vol. 3. Academic Press, New York, pp. 143–246.
  8. ^ Badenoch, PR; Adams M; Coster DJ (February 1995). "Corneal virulence, cytopathic effect on human keratocytes and genetic characterization of Acanthamoeba". International Journal for Parasitology 25 (2): 229–39.  
  9. ^ Niederkorn, JY; Alizadeh H; Leher H; McCulley JP (May 1999). "The pathogenesis of Acanthamoeba keratitis". Microbes and Infection 1 (6): 437–43.  
  10. ^ Sharma, S; Garg, P; Rao, GN (2000). "Patient characteristics, diagnosis, and treatment of non-contact lens related Acanthamoeba keratitis.". The British journal of ophthalmology 84 (10): 1103–8.  
  11. ^ Bharathi JM, Srinivasan M, Ramakrishnan R, Meenakshi R, Padmavathy S, Lalitha PN; Srinivasan; Ramakrishnan; Meenakshi; Padmavathy; Lalitha (2007). keratitis: a three-year study at a tertiary eye care referral center in South India"Acanthamoeba"A study of the spectrum of . Indian J Ophthalmol 55 (1): 37–42.  
  12. ^ Pasricha, Gunisha; Savitri Sharma; Prashant Garg; Ramesh K. Aggarwal (July 2003). "Use of 18S rRNA Gene-Based PCR Assay for Diagnosis of Acanthamoeba Keratitis in Non-Contact Lens Wearers in India". Journal of Clinical Microbiology 41 (7): 3206–3211.  
  13. ^ "Free-living Amebic Infections". CDC. 
  14. ^ Walochnik, J; Sheikl, U; Haller-Schober, EM (2014). "Twenty Years of Acanthamoeba Diagnostics in Austria.". The Journal of Eukaryotic Microbiology 62 (1): 3–11. 
  15. ^ "Acanthamoeba". AOA. 
  16. ^ Sharma S, Garg P, Rao GN; Garg; Rao (October 2000). keratitis"Acanthamoeba"Patient characteristics, diagnosis, and treatment of non-contact lens related . Br J Ophthalmol 84 (10): 1103–8.  
  17. ^ a b Lindsay RG, Watters G, Johnson R, Ormonde SE, Snibson GR; Watters; Johnson; Ormonde; Snibson (September 2007). "Acanthamoeba keratitis and contact lens wear". Clin Exp Optom 90 (5): 351–60.  
  18. ^ Hammersmith KM (August 2006). keratitis"Acanthamoeba"Diagnosis and management of . Current Opinion in Ophthalmology 17 (4): 327–31.  
  19. ^ "Acanthamoeba: Treatment & Medication - eMedicine Infectious Diseases". Retrieved 2009-02-27. 
  20. ^ S. Singh and M. P. Sachdeva (July 23, 1994). "Acanthamoeba keratitis". BMJ 309 (6949): 273.  

External links

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.