Iodamoeba bütschlii
المؤلف:
Patricia M. Tille, PhD, MLS(ASCP)
المصدر:
Bailey & Scotts Diagnostic Microbiology
الجزء والصفحة:
13th Edition , p599-601
2025-09-27
159
General Characteristics Iodamoeba bütschlii, one of the nonpathogenic amebae, has a worldwide distribution. Generally, the acquisition rate for this organism is not as high as that for E. coli and E. nana.
The life cycle stages of I. bütschlii are exactly the same as those of E. nana. The trophozoite varies from 8 to 20 µm in diameter and has fairly active motility in a fresh stool preparation. The cytoplasm is granular, containing numerous vacuoles with ingested debris and bacteria. The cytoplasm is more vacuolated than in E. nana trophozoites. The nucleus has a large karyosome, which can be either centrally located or eccentric (Figures 1 and 2). On the permanent stained smear, the nucleus may appear to have a halo, and chromatin granules fan out around the karyosome. If the granules are on one side, the nucleus may appear to have a “basket nucleus” arrangement of chromatin, more commonly seen in the cyst stage. The trophozoites of I. bütschlii and E. nana may appear similar and are difficult to differentiate at the species level, even on the permanent stained smear. Both organisms are considered nonpathogenic. E. nana is recovered in clinical specimens much more frequently than is I. bütschlii.
Fig1. A, Trophozoites of Iodamoeba bütschlii. B and C, Cysts of I. bütschlii.
Fig2. A, Iodamoeba bütschlii trophozoites. B, I. bütschlii cyst. C, I. bütschlii cyst. D, I. bütschlii cyst. (B courtesy Dr. Henry Travers, Sioux Falls, S.D.)
I. bütschlii cysts are round to oval. The glycogen vacuole is so large that occasionally the cyst collapses on itself. Because nuclear multiplication does not occur in the cyst form, the mature cyst contains a single nucleus. The cysts measure approximately 5 to 20 µm in diameter and are rarely confused with those of other amebae (see Figures 1 and 2).
Epidemiology
Transmission of I. bütschlii occurs through the ingestion of mature cysts from contaminated food or water. This organism is also found in warm, moist climates and in other areas with a low standard of personal hygiene and poor sanitary conditions.
Pathogeneis and Spectrum of Disease
I. bütschlii is considered nonpathogenic and does not cause disease.
Laboratory Diagnosis
Although I. bütschlii cysts sometimes can be seen in a wet preparation, definitive identification relies on the examination of permanent stained smears.
Therapy
Specific treatment is not recommended for I. bütschlii. Because these nonpathogenic amebae are acquired through fecal-oral contamination, both pathogens and nonpathogens can be found in the same patient. If few organisms are present, extended microscopic examination and multiple organism measurements are required for definitive identification. It is always important to report pathogens and nonpathogens, because they are acquired in similar ways.
Prevention (E. hartmanni, E. nana, I. bütschlii)
Prevention depends on adequate disposal of human excreta and improved personal hygiene, preventive measures that apply to most of the intestinal protozoa.
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