History

Fact Explanation
Keratitis [1] Common in swimmers and contact lenses users. [7] Clinical symptoms are pain, tearing, photophobia, blepharospasm, and blurred vision [8]. The above symptoms are preceded by the sensation of foreign body in eyes. Keratitis usually occurs in immune-competent individuals. [8]
Granulomatous amebic encephalitis (GAE) This is common in immunocompromised patients. [1,2,8] Usually this is an insidious onset sub acute diffuse meningoencephalitis. Most of the patients will have focal neurologic signs. Seizures, change in mental status, hemiparesis, Headache, visual disturbances (diplopia and photophobia), ataxia, hallucinations, personality changes and sleep disturbances are other symptoms.
Skin manifestations [4] These include papules, pustules, non-healing ulcers, nodules with overlying erythema, or subcutaneous abscesses. The skin papules may be painful. [6] In immune-competent individuals the first manifestation of disseminated disease is the skin lesions. [3]
Disseminated acanthamebiasis This is an extremely rare entity of the disease and the disease involves organs other than the central nervous system. [3,5]
Osteomyelitis [3] This is an extremely rare presentation.
References
  1. MARCIANO-C.F, PUFFENBARGER R, CABRAL GA. The increasing importance ofAcanthamoeba infections. J Eukaryot Microbiol [online] 2000;47:29-36. [viewed 18 April 2014] Available from: DOI: 10.1111/j.1550-7408.2000.tb00007.x
  2. MARTINEZ AJ. Is Acanthamoeba encephalitis an opportunistic infection? Neurology [online] 1980;30:567-74.[viewed 18 April 2014] Available from: doi: 10.1212/WNL.30.6.567
  3. JORDAN P. S., RENE L. G., EDWARD S. K., KHALIL G. G. Disseminated Acanthamebiasis in a Renal Transplant Recipient with Osteomyelitis and Cutaneous Lesions: Case Report and Literature Review. Clin Infect Dis [online] 2002: 35 (5) [viewed 18 April 2014] Available from: doi: 10.1086/341973
  4. WILEY CA, SAFRIN RE, DAVIS CE, et al. Acanthamoeba meningoencephalitis in a patient with AIDS. J Infect Dis [online] 1987;155:130-133. [viewed 18 April 2014] Available from: doi: 10.1093/infdis/155.1.130
  5. JEANETTE P. S., CAROL A. K., MARK L., DENNIS M. S., GOVINDA S. V., STANLEY C. D. Disseminated Acanthamoeba Infection in Patients with AIDS: Case Reports and Review. Clin Infect Dis. [online] 1995: 20 (5): 1207-1216. [viewed 18 April 2014] Available from: doi: 10.1093/clinids/20.5.1207
  6. VAN HAMME C, DUMONT M, DELOS M, LACHAPELLE JM. Cutaneous acanthamoebiasis in a lung transplant patient. Ann Dermatol Venereol [online] 2001;128:1237–40. [viewed 18 April 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/11908170
  7. BADENOCH P.R, “The pathogenesis of Acanthamoeba keratitis,” Australian and New Zealand Journal of Ophthalmology. [online] 1991: 19 (1) 9–20. [viewed 18 April 2014] Available from: DOI: 10.1111/j.1442-9071.1991.tb01794.x
  8. BENJAMIN CLARKE, ARTI SINHA, DIPAK N. PARMAR, EVRIPIDIS SYKAKIS. Advances in the Diagnosis and Treatment of Acanthamoeba Keratitis. Journal of Ophthalmology [online] 2012: 2012. [viewed 18 April 2014] Available from: http://dx.doi.org/10.1155/2012/484892

Examination

Fact Explanation
Signs of keratitis The conjunctiva is hyperemic. Corneal ulceration and lid edema are evident. The intraocular pressure may be elevated. Accumulated pus will produce a hypopyon in latter stages of the disease. Cataract formation will produce absent red reflex on examination with an ophthalmoscope. A corneal ring stromal infiltrate (dendritiform epitheliopathy) is pathognomonic. [2]
Central nervous system examination This will reveal focal neurological signs, hemiparesis, meningismus (positive Babinski sign, and Kernig sign), ataxia, and cranial nerve lesions. [3]
Examination of the mental status Often altered mental status is found.
Fever [3] Fever may or may not present.
Skin lesions Common in the extremities but can appear over the face and trunk as well. Usually these are papules, pustules, non-healing ulcers, nodules with overlying erythema, or subcutaneous abscesses. [1]
References
  1. WILEY CA, SAFRIN RE, DAVIS CE, et al. Acanthamoeba meningoencephalitis in a patient with AIDS. J Infect Dis [online] 1987;155:130-133. [viewed 18 April 2014] Available from: doi: 10.1093/infdis/155.1.130
  2. BENJAMIN CLARKE, ARTI SINHA, DIPAK N. PARMAR, EVRIPIDIS SYKAKIS. Advances in the Diagnosis and Treatment of Acanthamoeba Keratitis. Journal of Ophthalmology [online] 2012: 2012. [viewed 18 April 2014] Available from: http://dx.doi.org/10.1155/2012/484892
  3. Parasites - Acanthamoeba - Granulomatous Amebic Encephalitis (GAE); Keratitis. Centers for Disease Control and Prevention. [online] [viewed 18 April 2014] Available from: http://www.cdc.gov/parasites/acanthamoeba/disease.html

Differential Diagnoses

Fact Explanation
Fungal keratitis [1] Fungal infection of the cornea.
Herpes simplex virus keratitis HSV keratitis is common. The clinical course during the initial course of the illness is often similar in both conditions. [1]
Aspergillosis Involves lungs, skin, nervous system and cardiovascular system. [2]
Coccidioidomycosis Presents with acute or sub-acute pneumonia. [3]
Histoplasmosis Causes pneumonia like clinical picture. Fever, dry and non-productive cough and chest pain. [4]
Neruocysticercosis This is caused by infection of Taenia solium larva. Patients present with seizures. [5]
Toxoplasmosis Infection of the eye causes retinochoroiditis commonly. Photophobia, tearing, and blurred vision may progress to blindness. Infection of the central nervous system causes seizures, behavioral changes, headache and ataxia. [6]
Tuberculosis This is a multi-system disease and involve eyes, central nervous system (headache, meningitis, seizures), skin and respiratory system.
References
  1. BENJAMIN CLARKE, ARTI SINHA, DIPAK N. PARMAR, EVRIPIDIS SYKAKIS. Advances in the Diagnosis and Treatment of Acanthamoeba Keratitis. Journal of Ophthalmology [online] 2012: 2012. [viewed 18 April 2014] Available from: http://dx.doi.org/10.1155/2012/484892
  2. THOMAS J. W., ELIAS J. A., DAVID W. D., et al. Treatment of Aspergillosis: Clinical Practice Guidelines of the Infectious Diseases Society of America. Clin Infect Dis. [online]2008: 46 (3): 327-360 [viewed 18 April 2014] Available from: doi: 10.1086/525258
  3. JOHN N. G., NEIL M. A., JANIS E. B., ANTONINO C. Coccidioidomycosis. Clin Infect Dis. [online] 2005: 41 (9): 1217-1223. [viewed 18 April 2014] Available from: doi: 10.1086/496991
  4. Histoplasmosis. Centers for Disease Control and Prevention. [online] [viewed 18 April 2014] Available from: http://www.cdc.gov/fungal/diseases/histoplasmosis/symptoms.html
  5. HECTOR H. G., CARLTON A. W. E. THEODORE E. N., OSVALDO M. T. et al. Current Consensus Guidelines for Treatment of Neurocysticercosis. Clin. Microbiol. Rev [online] 2002: 15 (4) 747-756. [viewed 18 April 2014] Available from: doi: 10.1128/CMR.15.4.747-756.2002
  6. Toxoplasmosis. Centers for Disease Control and Prevention [online] [viewed 18 April 2014] Available from: http://www.cdc.gov/parasites/toxoplasmosis/

Investigations - for Diagnosis

Fact Explanation
Corneal scrapings or biopsy [1] If keratitis is suspected this will show Acanthamoeba trophozoites or cysts. The sample can be processed in a wet-mount to look for motile trophozoites or can be cultured. [1] The biopsy sample can be used for polymerase chain reaction.
Immunohistological staining of the scrapings or biopsy [1] This will stain Acanthamoeba specific monoclonal antibodies. [2]
Confocal microscopy This is a non-invasive and quick way to diagnose Acanthamoeba keratitis. [1]
Cerebrospinal fluid examination The lymphocytes and protein levels are elevated and glucose level is low.
Biopsy and or culture This will enable diagnosis from any other site.
CT brain Multiple nonenhancing lesions are seen in the cerebral cortex. CT is mandatory before the lumbar puncture to prevent the risk of cerebral herniation after the procedure.
References
  1. BENJAMIN CLARKE, ARTI SINHA, DIPAK N. PARMAR, EVRIPIDIS SYKAKIS. Advances in the Diagnosis and Treatment of Acanthamoeba Keratitis. Journal of Ophthalmology [online] 2012: 2012. [viewed 18 April 2014] Available from: http://dx.doi.org/10.1155/2012/484892
  2. TURNER M. L., COCKERELL E. J., BRERETON H. M. et al., “Antigens of selected Acanthamoeba species detected with monoclonal antibodies,” International Journal for Parasitology [online] 2005: 35 (9) 981–990. [viewed 18 April 2014] Available from: http://dx.doi.org/10.1016/j.ijpara.2005.03.015

Management - General Measures

Fact Explanation
Patient education Contact lens users should adhere to proper cleaning techniques and should regularly clean there lenses. Patients are advised not to wear the lenses while showering and swimming. [2]
Treatment of glaucoma Acanthameba keratitis may result in glaucoma and permanent visual loss. [1] Intraocular pressure measurements should be done for early detection of glaucoma and treated as necessary.
Treatment of cataracts Cataract is a known complication of keratitis and also may arise secondary to use of topical steroids. [3]
References
  1. KELLEY PS, DOSSEY AP, PATEL D, WHITSON JT, HOGAN RN, CAVANAGH HD. Secondary glaucoma associated with advanced acanthamoeba keratitis. Eye Contact Lens. [online] 2006 Jul;32(4):178-82. [viewed 18 April 2014] Available from: DOI: 10.1097/01.icl.0000189039.68782.fe
  2. Parasites - Acanthamoeba - Granulomatous Amebic Encephalitis (GAE); Keratitis. Centers for Disease Control and Prevention. [online] [viewed 18 April 2014] Available from: http://www.cdc.gov/parasites/acanthamoeba/health_professionals/acanthamoeba_keratitis_hcp.html
  3. LOTTI R, DART JK. Cataract as a complication of severe microbial keratitis. Eye (Lond). [online] 1992;6 ( Pt 4):400-3. [viewed 18 April 2014] Available from: doi:10.1038/eye.1992.82

Management - Specific Treatments

Fact Explanation
Topical antimicrobial agents [2] Chlorohexidine and polyhexamethylen biguanide are effective topical antimicrobials against trophozoites and cysts.
Topical steroid [2] The use of topical steroids is controversial but topical steroids are added after the completion of antimicrobial treatment. [3]
Corneal debridement [2] Often patients need aggressive treatment with both medical and surgical approaches.
Laser photokeratectomy [2] Newer treatment option for keratitis.
Medical treatment for Granulomatous amebic encephalitis Combined therapy of pentamidine, an azole (fluconazole or itraconazole), a sulfadiazine is effective. Flucytosine can also be combined.
Combined therapy for disseminated disease Intravenous pentamidine is used mainly. In addition topical chlorhexidine gluconate [4], and 2% ketoconazole cream andoral itraconazole is prescribed to the patient. Flucytosine can also be used. [1]
References
  1. VAN HAMME C, DUMONT M, DELOS M, LACHAPELLE JM. Cutaneous acanthamoebiasis in a lung transplant patient. Ann Dermatol Venereol [online] 2001;128:1237–40. [viewed 18 April 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/11908170
  2. BENJAMIN CLARKE, ARTI SINHA, DIPAK N. PARMAR, EVRIPIDIS SYKAKIS. Advances in the Diagnosis and Treatment of Acanthamoeba Keratitis. Journal of Ophthalmology [online] 2012: 2012. [viewed 18 April 2014] Available from: http://dx.doi.org/10.1155/2012/484892
  3. PARK D. H., PALAY D. A., DAYA S. M., STULTING R. D., KRACHMER J. H., HOLLAND E. J. “The role of topical corticosteroids in the management of Acanthamoeba keratitis,” Cornea [online] 1997: 16 (3) 277–283. [viewed 18 April 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/9143798
  4. HAY J, KIRKNESS CM, SEAL DV, WRIGHT P. Drug resistance and Acanthamoeba keratitis: the quest for alternative antiprotozoal chemotherapy. Eye (Lond). [online] 1994;8 (5):555-63. [viewed 18 April 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/7835453