View source for Acanthamoeba

==Background==
===Microbiology===

*One of the [[free-living amoebae]]
*Seventeen genotypes (T1-T17), of which 10 have caused disease in humans
*Most common is ''[[Acanthamoeba castellanii]]'' complex (T4)
*Species traditionally organized morphologically into 3 groups

{| class="wikitable"
!Group
!Species
!Trophozoite Size
!Cyst Size
|-
|I
|''A. astronyxis'', ''A. comandoni'', ''A. tubiashi'', ''A. byersi''
|30-125 μm
|16-35 μm
|-
|II
|''A. castellanii'', ''A. polyphaga'', ''A. rhysodes'', ''A. hatchetti''
|15-45 μm
|≤18 μm
|-
|III
|''A. culbertsoni'', ''A. royreba'', ''A. lenticulata''
|15-45 μm
|<18 μm with different morphologies
|}

===Life Cycle===

*Cysts and trophozoites can cause disease

===Epidemiology===

*More common in immunocompromised patients, with risk factors including [[AIDS]], liver disease, diabetes, organ transplantation, corticosteroid use, chemotherapy, and rituximab

==Clinical Manifestations==
===Granulomatous amebic encephalitis===

*Subacute presentation of encephalitis (fever, headache, nuchal rigidity, behaviour changes, altered level of conciousness, focal neurological deficiets)
*Often preceded by cutaneous lesions by months
**May include ulcers, nodules, and subcutaneous abscesses
**Amoebic granulomas on biopsy

===Non-neurological disseminated acanthamoebiasis===

*Rarely, patients may have disseminated disease without evidence of CNS involvement
*Mostly seen in patients with AIDS, transplant, or prolonged corticosteroid use
*Most commonly involves skin, but can involve liver, lungs, and bones

===Amoebic keratitis===

*Sight- and eye-threatening infection
*Often secondary to corneal trauma or improper contact lens hygiene
*Present with severe pain, photophobia, tearing
*May see dendiform epitheliopathy or stromal ring

== Diagnosis ==

* Ameba culture on nutrient agar with layer of gram-negative bacteria at 30ºC (cornea/skin) or 37–C (brain/lung)
* Species identification done with 18S rDNA sequencing

==Management==
===Granulomatous amebic encephalitis===

*Can consider a combinaction of [[Is treated by::pentamidine]], [[Is treated by::azoles]], [[Is treated by::flucytosine]], [[Is treated by::sulfadiazine]], [[Is treated by::miltefosine]], [[Is treated by::amikacin]], and [[Is treated by::voriconazole]]

===Amoebic keratitis===

*Can be treated with any of:
**[[Is treated by::PHMB]]
**[[Is treated by::Chlorhexadine]]
**Topical and oral [[Is treated by::voriconazole]]
**[[Is treated by::Propamidine]]
**[[Is treated by::Hexamidine]]

{{DISPLAYTITLE:''Acanthamoeba''}}
[[Category:Protozoa]]