[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 3 The Amebas
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Achromatic granules
surrounding the
karyosome
No peripheral
chromatin
Vacuole
Cytoplasm
Karyosome
(usually central)
Ingested
bacteria
A
Size range: 8-22 m
B
Average size: 12-18 m
FIGURE 3-16 A, Iodamoeba bütschlii trophozoite. B, Iodamoeba bütschlii trophozoites. (B from Forbes BA, Sahm DF,
Weissfeld AS: Bailey & Scott’s diagnostic microbiology, ed 12, St Louis, 2007, Mosby.)
TABLE 3-11
Iodamoeba bütschlii
Trophozoite: Typical
Characteristics at a Glance
TABLE 3-12
Iodamoeba bütschlii Cyst:
Typical Characteristics at
a Glance
Parameter
Description
Size range 8-22 µm
Motility
Sluggish, usually progressive
Number of nuclei One
Karyosome
Large, usually central
refractive achromatic
granules may or may not
be present
Peripheral chromatin Absent
Cytoplasm
Coarsely granular and
vacuolated
Cytoplasmic inclusions Bacteria
Yeast cells
Other debris
Parameter
Description
Size range 5-22 µm
Shape
Ovoid, ellipsoid, triangular,
other shapes
Number of nuclei One
Karyosome
Large, eccentric achromatic
granules on one side may
be present
Peripheral chromatin Absent
Cytoplasm
Coarsely granular and
vacuolated
Cytoplasmic inclusions Well-defined glycogen mass
Granules may be present
5 µm, whereas others may be as large as 22 µm
in size (Fig. 3-17; Table 3-12). I. bütschlii cysts
vary in shape. Ovoid, ellipsoid, triangular, or
other shapes of these cysts may be seen. Just like
those of the corresponding trophozoite, I. bütschlii
cysts contain one nucleus. The large karyosome
is typically seen in an eccentric position.
Achromatic granules, indistinct in iodine preparations,
may be seen on one side of the karyosome.
Granules may occasionally be present in
the coarsely granulated and vacuolated cytoplasm.
Chromatoid bars are absent. A welldefined
glycogen mass with definite borders is
characteristic and is considered as an important
diagnostic feature of the I. bütschlii cyst.
Laboratory Diagnosis
The examination of stool samples for the trophozoites
and cysts of I. bütschlii is the method of