[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

APPENDIX D Answers to Test Your Knowledge (Review Questions)
347
the brain, causing rapid tissue
destruction.
D. Central nervous system (CNS) infections
with Acanthamoeba are also
known as granulomatous amebic
encephalitis (GAE). On occasion,
Acanthamoeba invade other areas of
the body, including the kidneys, pancreas,
prostate, and uterus, and form
similar granulomatous lesions. Acanthamoeba
infections of the cornea
of the eye are known as amebic
keratitis.
3-9. A. True
3-10. B
3-11. 1. A
2. A
3. A
4. C
5. B, D
6. B
3-12. Amebic trophozoites and cysts may be
seen in stool samples submitted for parasite
study. Trophozoites are primarily
recovered from stools that are of soft,
liquid, or loose consistency. Formed stool
specimens are more likely to contain
cysts. The morphologic forms present in
samples other than stool are noted on an
individual basis. It is important to point
out that the presence of either or both
morphologic forms is diagnostic. Proper
determination of organism size, using the
ocular micrometer (see Chapter 2), is
essential when identifying the amebas. In
addition, the appearance of key nuclear
features, such as the number of nuclei
present and the positioning of the nuclear
structures, is crucial to correctly differentiate
the amebas. The presence of other
amebic structures and characteristics,
such as cytoplasmic inclusions and motility,
also aids in the identification of the
amebas. Traditional microscopic procedures
include saline wet preparations,
iodine wet preparations, and permanent
stains. The saline wet preparation and
iodine wet preparation each have an
CHAPTER 4
advantage supporting their use. Saline
wet preparations are of value because
they will often show motility of the
amebic trophozoites. The internal cytoplasmic,
as well as the nuclear structures,
may be more readily seen with the use of
iodine wet preparations. It is important
to note that permanent smears of samples
suspected of containing amebas must be
performed to confirm parasite identification.
In most cases, the key identifying
features cannot be accurately distinguished
without the permanent stain.
The permanent stain allows for many of
the otherwise refractive and invisible
structures to be more clearly visible and
thus easier to identify. The permanent
smear procedure may, however, shrink
amebic parasites, causing measurements
smaller than those typically seen in wet
preparations.
4-1. A. 3
B. 4
C. 2
D. 6
E. 1
F. 5
4-2. Intestinal flagellates: Giardia intestinalis,
Chilomastix mesnili, Dientamoeba fragilis,
Trichomonas hominis, Enteromonas
hominis, Retortamonas intestinalis; atrial
flagellates: Trichomonas tenax, Trichomonas
vaginalis.
4-3. Any of the flagellates may be found in the
United States.
4-4. Trichomonas vaginalis.
4-5. The life cycle of Trichomonas vaginalis
is relatively simple. T. vaginalis trophozoites
reside on the mucosal surface of
the vagina in infected women. The
trophozoites multiply by longitudinal
binary fission in the vagina, feeding on
bacteria and leukocytes. In the male, the
organism typically invades the prostate
gland and epithelium of the urethra.