Detection and identification of Acanthamoeba species and Naegleria fowleri in central nervous system or ocular specimens.
Microscopy: Direct Wet Preparation
Primary Amoebic Encephalitis (PAM)
Chronic Ganulomatous Amebic Encephalitis (GAE)
Cerebrospinal fluid (CSF)
Tissue (brain, lung, skin, corneal scraping)
Submit immediately without delay.
|Corneal scraping||OK||NO||NO||Sterile screw cap container with 1 mL saline|
|Tissue||OK||NO||NO||Sterile screw cap container with 1 mL saline|
|CSF||OK||NO||NO||Sterile screw cap container with 1 mL CSF|
Note: Preferred specimen for Acanthamoeba culture from an ocular source is corneal scraping or biopsy. Swab is suboptimal and may result in a falsely negative result.
Reject Due To
|Specimens other than||CSF, corneal scrapings and tissue|
Detection and identification of Acanthamoeba species, Balamuthia mandrillaris and Naegleria fowleri in central nervous system or ocular specimens
Acanthamoebae spp., Naegleria fowleri and Balamuthia mandrillaris are free living amebas that are aerobic, eukaryotic protists. N. fowleri has three life cycle stages: trophozoites, flagellates, and cysts. Both Balamuthia mandrillaris and Acanthamoeba spp. have a trophozoite stage, non-motile and active, respectively; and cyst stage.
Human exposure to Acanthamoeba spp. is widespread given its presence in soil and fresh water in a variety of geographic conditions and areas; illness caused by Acanthamoeba spp. is most commonly found in individuals with compromised immune systems or in contact lens wearers.
Granulomatous amebic encephalitis (GAE) commonly occurs when Acanthamoeba spp. enters the lower respiratory tract or ulcerated or broken skin in individuals with compromised immune systems. Chronic granulomatous lesions or amebic keratitis (AK), of the eye and cornea can also be caused by some Acanthamoeba sp. AK infections can occur in contact lens wearers and may be attributed to poor contact lens hygiene or in individuals who have had corneal trauma. AK infections may result in blindness if left untreated.
Diagnosis can be made through microscopic examination of wet mount preparations of fresh CSF showing motile amoebae and of stained smears or through microscopic examination of scrapings or aspirates of the eye, cornea, or skin lesions.
Organisms seen on stains of the original specimen smear and/or growth on culture media are positive tests.Detection of Amoeba in ocular and sterile specimens constitutes a medical emergency. Positive findings will be telephoned to the ordering physician.
The preferred specimens for Acanthamoeba ocular culture are corneal scrapings and/or biopsy. Swabs are suboptimal and may result in a falsely-negative
Eberhard, M., Gabrielli, A., Savioli, L., and Visvesvara, G. 2008. Naegleriasis, Acanthamediasis, and Balamuthiasis, p. 438-441. In Heymann, D. L., Control of Communicable Diseases Manual, 19th ed. American Public Health Association, Washington, DC.
Koshy, A. A., Blackburn, B. G., and Singh, U. 2010. Free-Living Amebas, p. 3427-3436. In Mandell, D., Bennett, J. E., and Dolin, R. Principles and practice of infectious diseases, 7th ed., vol. 2. Churchill Livingstone, Elsevier, Philadelphia, PA.
Ma P, Visvesvara GS, Martinez AJ, et al. 1990. Naegleria and Acanthamoeba infections. Rev. Infect. Dis. 12:490-513.
Visvesvara, G. S. 2007. Pathogenic and Opportunistic Free-Living Amebae, p. 2082-2091. In Murray, P. R., Baron, E. J., Jorgensen, J. H., Landry, M. L., and Pfaller, M. A. Manual of Clinical Microbiology, 9th ed., vol. 2. ASM Press, American Society for Microbiology, Washington, DC.
|Status||Days||Analytic Time||Maximum Laboratory Time||Specimen Retention|
|URGENT||Monday – Sunday||Same day||24h||1 week|
|Status||Days||Analytic Time||Maximum Laboratory
|7 days||9 days||1 week|
Performing Laboratory Location
Newfoundland & Labrador Public Health Laboratory, St. John’s, NL.
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