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Sappinia spp. (True Pathogen – Granulomatous Amebic Encephalitis/GAE)

Sappinia spp. (True Pathogen – Granulomatous Amebic Encephalitis/GAE)

The genus Sappinia with the single species Sappinia pedata was established for an amoeba with two nuclei and pedicellate "cysts" by Dangeard in 1896. In 1912, Alexeieff transferred an also double nucleated, but apparently sexually reproducing amoeba to this genus as Sappinia diploidea that had been described as Amoeba diploidea by Hartmann and Nägler in 1908. Molecular analyses have confirmed the differentiation between S. pedata and S. diploidea; however, the genus splits into more than two well separated clusters. The genus Sappinia is now classified as a member of the Thecamoebidae and, moreover, as potentially pathogenic. Subacute or chronic CNS infections due to Acanthamoeba spp, Balamuthia mandrillaris, and Sappinia spp., which occasionally cause cerebral abscess, are termed granulomatous amebic encephalitis (GAE).  In 2001, Gelman and colleagues reported a case of severe encephalitis in an immunocompetent young man caused by Sappinia.  Another case of GAE and abscess formation was reported from Turkey in 2009; in this case, the patient died.   
Sappinia trophozoite andcyst  

Trophozoites in tissue (note the appearance of 2 nuclei)




Life Cycle:
The life cycle is similar to that seen with Acanthamoeba spp.; like Acanthamoeba spp., Sappinia does not have a flagellated stage in its life cycle as do organisms classified as N. fowleri.

The amebae may enter through the lower respiratory tract or through ulcerated or broken skin, causing GAE, particularly those who are immunocompromised. 

The amoebae have a cosmopolitan distribution in soil and water, providing multiple opportunities for contacts with humans and animals, as evidenced by antibody titers in surveyed human populations.  The numbers of infections caused by these amoebae are low in comparison to other protozoal parasitic infections.  Pathogenic free-living amebae can be isolated from freshwater lakes, thermally polluted waters, sediment, thermal springs, swimming pools, soil, air conditioning vents, air, and the domestic water supply. In addition to causing human disease, these organisms also can harbor intracellular pathogenic bacteria such as Legionella pneumophila and may serve as vectors of bacterial infections in humans.

Clinical Features:
GAE.  In one of the cases of Sappinia amoebic encephalitis that has been reported, a sinus infection occurred prior to the onset of symptoms. The individual developed nausea, vomiting, bifrontal headache, photophobia, and blurry vision. A loss of consciousness occurred for a brief. A successful outcome in this patient was reported after surgical excision of a tumor-like mass in the brain and treatment using azithromycin, intravenous pentamidine, itraconazole, and flucytosine.
Clinical Specimen:
Tissue or Scans:  In the differential diagnosis, other space‑occupying lesions of the CNS (tumor, abscess, fungal infection, etc.) must also be considered.  A solitary tumor-like mass without an abscess wall can be seen via MRI.
PCR:  Multiplex PCR studies can distinguish Acanthamoeba, Balamuthia, and Naegleria from Sappinia for simultaneous detection of the four genera.

Laboratory Diagnosis:  THIS REQUEST IS ALWAYS A STAT!
CSF specimens should never be refrigerated prior to examination. When centrifuging the CSF, low speeds (250 ´ g) should be used so that the trophozoites are not damaged. Although bright‑field microscopy with reduced light is acceptable, phase microscopy, if available, is recommended. Use of smears stained with Giemsa or Wright’s stain or a Giemsa‑Wright’s stain combination can also be helpful.
Culture on nonnutrient agar with an overlay of bacteria and on tissue culture cells is also an option.

Organism Description:
Trophozoite:  Sappinia amoebae can be distinguished from other free-living amebae by the presence of a distinctive double nucleus in which the 2 nuclei are closely apposed with a central flattening. Two nucleoli are found in the double nucleus. These structures can be observed in paraffin sections stained with H & E, Giemsa, or Periodic Acid Schiff. The amoebae are readily observed in cryostat sections stained with H & E. Brain tissue can be fixed in glutaraldehyde and prepared for transmission electron microscopy to visualize the amoebae in tissue.

Laboratory Report:
Sappinia confirmed (confirmation to genus/species is available through CDC).
Free-living amebae present.

Treatment has included surgery, as well as azithromycin, intravenous pentamidine, itraconazole, and flucytosine.
Garcia, L.S. 2007.  Diagnostic Medical Parasitology, 5th ed., ASM Press, Washington, D.C.

General preventive measures are similar to those for Naegleria, Acanthamoeba, and Balamuthia.