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Acanthamoeba keratitis
Classification and external resources
eMedicine med/10
MeSH D015823

Acanthamoeba keratitis is a rare disease where amoebae invade the cornea of the eye.

Contents

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.[1][2][3][4] For this reason, contact lenses must be properly disinfected before wearing, and should be removed when swimming or surfing.

However, elsewhere in the world, many cases of Acanthamoeba present in non-contact lens wearers.[5][6]

Diagnosis

To detect Acanthamoeba on a contact lens in a laboratory, a sheep blood agar plate with a layer (a lawn) of E. coli is made. Part of the contact lens is placed on the agar plate. If Acanthamoeba are present, they will ingest the bacteria, leaving a clear patch on the plate around the area of the lens. 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 interior AC. Late stages of the disease also produces a ring shaped corneal ulcer.[7]

Presentation

Signs and symptoms include severe pain, severe keratitis (similar to stromal herpetic disease), corneal perineuritis, ring ulcer (although this is late in the disease process)

Treatment

One treatment used is PHMB.[8]

Propamidine isethionate has also shown some effectiveness.[9]

Another possible agent is chlorhexidine.[10]

Keratoplasty may sometimes be required.[9]

A combined regimen of propamidine, miconazole nitrate, and neomycin has also been suggested. [11]

References

  1. ^ Auran, JD; Starr MB, Jakobiec FA (1987). "Acanthamoeba keratitis. A review of the literature". Cornea 6 (1): 2–26. doi:10.1097/00003226-198706010-00002. PMID 3556011.  
  2. ^ 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.
  3. ^ 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. doi:10.1016/0020-7519(94)00075-Y. PMID 7622330.  
  4. ^ Niederkorn, JY; Alizadeh H, Leher H, McCulley JP (May 1999). "The pathogenesis of Acanthamoeba keratitis". Microbes and Infection 1 (6): 437–43. doi:10.1016/S1286-4579(99)80047-1. PMID 10602676.  
  5. ^ Sharma S, Garg P, Rao GN. "Patient characteristics, diagnosis, and treatment of non-contact lens related Acanthamoeba keratitis." The British Journal of Ophthalmology. 2000 Oct;84(10):1103-8. PMID: 11004092
  6. ^ Bharathi JM, Srinivasan M, Ramakrishnan R, Meenakshi R, Padmavathy S, Lalitha PN (2007). "A study of the spectrum of Acanthamoeba keratitis: a three-year study at a tertiary eye care referral center in South India". Indian J Ophthalmol 55 (1): 37–42. PMID 17189885. http://www.ijo.in/article.asp?issn=0301-4738;year=2007;volume=55;issue=1;spage=37;epage=42;aulast=Bharathi.  
  7. ^ 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. doi:10.1128/JCM.41.7.3206-3211.2003. PMID 12843065. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=165372.  
  8. ^ Sharma S, Garg P, Rao GN (October 2000). "Patient characteristics, diagnosis, and treatment of non-contact lens related Acanthamoeba keratitis". Br J Ophthalmol 84 (10): 1103–8. PMID 11004092. PMC 1723254. http://bjo.bmj.com/cgi/pmidlookup?view=long&pmid=11004092.  
  9. ^ a b Lindsay RG, Watters G, Johnson R, Ormonde SE, Snibson GR (September 2007). "Acanthamoeba keratitis and contact lens wear". Clin Exp Optom 90 (5): 351–60. doi:10.1111/j.1444-0938.2007.00172.x. PMID 17697181. http://dx.doi.org/10.1111/j.1444-0938.2007.00172.x.  
  10. ^ Hammersmith KM (August 2006). "Diagnosis and management of Acanthamoeba keratitis". Curr Opin Ophthalmol 17 (4): 327–31. doi:10.1097/01.icu.0000233949.56229.7d. PMID 16900022. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?an=00055735-200608000-00002.  
  11. ^ "Acanthamoeba: Treatment & Medication - eMedicine Infectious Diseases". http://emedicine.medscape.com/article/211214-treatment. Retrieved 2009-02-27.  
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