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Protozoal Microorganisms as Intestinal Parasites 65

be caused by pathogenic bacteria, viruses, or parasites.
MICROSCOPIC DIAGNOSTIC Because treatment for the various types of dysentery is

FEATURE quite different, it is necessary to determine the cause of
the dysentery prior to initiating treatment. Diagnosis is
most often made through clinical signs and stated symp-
General toms expressed by the patient, but dysentery should be
Classification Amoeba
confirmed by microscopic examination because diarrhea
Organism Iodamoeba butschlii by any of the three entities listed previously are capable of
Specimen Required Stool specimen producing similar signs and symptoms. Bacterial dysen-
tery is diagnosed and the causative organism determined
Stage Trophozoites most
diagnostic stage by culture of the bacterial strain on nutrient media, after
which an antibiotic sensitivity test will indicate the anti-
Size 6–20 μm for tropho-
zoite and 6–15 μm for bacterial agent that should be most effective in control-
cyst stages ling the disease. Viruses may be grown in cell cultures but
Shape Irregularly shaped this procedure is quite time consuming, and may become
and elongated tro- contaminated. The most common manner of diagnosing
phozoites and slightly a viral infection is by the indirect process of the antibody
oval cysts titer where the body’s immune system reacts to the infec-
Motility Nondirectional tion and by the presence of clinical signs and symptoms.
Nucleus(i) 1 for trophozoites Parasites, on the other hand, are discovered by examina-
and 1 for cysts tion of blood and body wastes by microscopic evalua-
Cytoplasm Sometimes includes tion of wet mounts and stained specimens that may also
ingested bacteria and necessitate concentration techniques.
is vacuolated
Other Features Large and concentric
karyosomes in both OTHER ASSOCIATED CONDITIONS
stages OF INTESTINAL INFECTIONS
Large defined glyco-
gen vacuole is charac- Balantidium coli, a normal parasite of swine as described
teristic of this species previously, is a pathogenic ciliate and can cause severe
colitis, or irritation of the bowel, and is mentioned for the
I. butschlii
following reasons. The clinical manifestations are very
Trophozoite Cyst
similar to the intestinal amoebal infections where the diag-
nosis is most often made by the microscopic examination
of stool specimens before treatment is begun. Treatment
Delmar/Cengage Learning used primarily for bacterial infections. Pseudomembra-
for B. coli infections is with tetracycline, an antibiotic
nous colitis may mimic parasitic infections, but is an
infection of the colon that is often caused by a bacterium
called Clostridium difficile. The illness is characterized
by offensive-smelling diarrhea, fever, and abdominal pain,
which are similar to signs and symptoms presented by
victims of an intestinal parasitic disease. Therefore, para-
DIFFERENTIATING BACTERIAL sitic or bacterial infections should be ruled out by specific
DYSENTERY FROM AMEBIC lab tests to provide appropriate treatment.
DYSENTERY Other intestinal diseases characterized by severe
dysentery are Crohn’s disease and ulcerative coli-
Dysentery is a disease that is characterized by diarrhea tis, but both of these conditions are rare in the tropics
and contains both blood and mucus. The condition may where parasitosis abounds. Radiological studies and