Microbiology
An amoeba from freshwater. Includes A. astronyxis, A. castellani, A. culbertsoni, A. hatchetti, A. palestinensis, A. polyphaga, A. rhysodes. A cousin of Naegleria.
Epidemiologic Risks
Ubiquitous: has been found in air, sewage, ocean water, swimming pools, tap water, bottled water, hospitals, air-conditioning units, human skin, nasal cavities, throats, and intestines, plants and animals (Pubmed).
Swimming in freshwater lakes is the big risk for encephalitis, water, and amoeba, goes up nose to the first cranial nerve and into the brain.
Ritual nasal rinsing a risk (PubMed), not unlike the use of Neti Pots (PubMed)(PubMed). Here is a suggestion: only squirt sterile water up your nose.
There was a case of fulminant Acanthamoeba castellanii encephalitis in a patient with CLL treated with ibrutinib (Pubmed).
Syndromes
Primary meningitis, granulomatous amoebic encephalitis in the immunocompetent, keratitis (especially associated with contact lenses (PubMed)) and disseminated cutaneous acanthamebiasis in AIDS and other immunoincompetent patients.
Treatment
A hodgepodge of therapies have been tried (Pubmed), which is superior is unknown and unknowable.
Meningitis- see CDC Suggestions:
"Several patients with granulomatous amebic encephalitis (GAE) have been successfully treated with combinations of pentamidine, sulfadiazine, flucytosine, and either fluconazole or itraconazole. GAE in an AIDS patient was treated successfully with sulfadiazine, pyrimethamine and fluconazole combined with surgical resection of the CNS lesion. Chronic Acanthamoeba meningitis was successfully treated in 2 children with a combination of oral trimethoprim/sulfamethoxazole, rifampin and ketoconazole. Disseminated cutaneous infection in an immunocompromised patient was treated successfully with IV pentamidine, topical chlorhexidine and 2% ketoconazole cream, followed by oral itraconazole and with voriconazole and amphotericin B lipid complex. Other reports of successful therapy have been described. Susceptibility testing of Acanthamoeba isolates has shown differences in drug sensitivity between species and even among strains of a single species; antimicrobial susceptibility testing is advisable."
Whatever combination I used, I would include Miltefosine (PubMed) in the mix.
No matter what you do, the meningitis will prove fatal, or worse, they will survive with permanent brain damage.
Similar therapy for disseminated and cutaneous disease. One case was treated with Miltefosine (PubMed).
I will leave the treatment of keratitis to ophthalmology.
Notes
They are also the host for Legionella and giant viruses like Mimivirus.
Last update: 02/16/20