1: ENTAMOEBA HISTOLYTICA Flashcards
Common associated disease or condition names
Intestinal amebiasis, amebic colitis, amebic dysentery, extraintestinal amebiasis
e trophozoite exhibits rapid, unidirectional,
progressive movement, achieved with the help of ______________________
finger-like hyaline pseudopods
The single nucleus typically contains a small central mass of chromatin known as _________
karyosome (karyosomal chromatin)
The karyosome of this amebic parasite is surrounded by chromatin material, a morphologic structure called ___________ ____________.
peripheral chromatin
Motility
Progressive, finger-like
pseudopodia
Number of nuclei
One
Karyosome
Small and central
Peripheral chromatin
Fine and evenly distributed
Cytoplasm
Finely granular
Cytoplasmic inclusions
Ingested red blood cells
The E. histolytica trophozoite contains a ____________ ____________ __________, which is often referred to as having a ground glass in appearance.
finely granular cytoplasm
Young cysts characteristically contain unorganized chromatin material that transforms into squared or round-ended structures called _____________
chromatoid bars
structures that contain condensed RNA material.
chromatoid bars
It is a cytoplasmic area without defined borders that is believed to represent stored food, is also usually visible in young cysts
glycogen mass
Nuclear variations during maturation
- eccentric (rather than the typical central) karyosomes
- thin plaques of peripheral chromatin, or
- a clump of peripheral chromatin at one side of the nucleus that appears crescent shaped.
The mature infective cyst is
quadrinucleated
RBCs, bacteria, yeast, and other debris are not found in the cyst stage.
True
Laboratory Diagnosis
- traditional wet preparation
- permanent staining techniques
- sigmoidoscopy procedure
- hepatic abscess material
A special medium known at ________ supports E. histolytica in culture.
TYI-S-33
Once the infective cyst is ingested, excystation occurs in the __________________.
small intestine
As a result of the nuclear division, a single cyst produces _____ motile trophozoites.
eight
These motile amebas settle
in the ______ of the large intestine, where they replicate by ________ fission and feed on living host cells
lumen, binary
Encystation occurs in the _________________
intestinal lumen
cyst formation is complete when ___ nuclei are present.
four
Liquid or semi-formed samples may show __________ if the intestinal motility is rapid.
trophozoites
_________ will form, on the other hand, if the intestinal motility is normal.
Cysts
The range of symptoms
varies and depends on two major factors:
(1) the location(s) of the parasite in the host; and
(2) the extent of tissue invasion
Asymptomatic Carrier State
(1) the parasite is a low-virulence strain;
(2) the inoculation into the host is low; and (3) the patient’s immune system is intact.
Symptomatic Intestinal Amebiasis
- amebic colitis
- amebic dysentery (characterized by blood and mucus in the stool)
Symptomatic Extraintestinal Amebiasis.
- trophozoites that migrate into the bloodstream are removed by and take up residence in the liver.
- amebic pneumonitis
- Venereal amebiasis
- Penile amebiasis
Treatment
Asymptomatic individuals may be treated
with:
- paromomycin
- diloxanide furoate (Furamide)
- metronidazole (Flagyl)
Patients showing symptomatic intestinal amebiasis:
- iodoquinol
paromomycin
diloxanide furoate
Symptomatic intestinal amebiasis treatment:
- Metronidazole
- Tinidazole
Entamoeba except E. histolytica,
E. dispar, and E. moshkovskii are differentiated by
isoenzyme analysis polymerase chain reaction (PCR), restriction fragment length
polymorphism (RFLP), and typing with
monoclonal antibodies
most invasive of the Entamoeba parasites and the only member of the family to cause colitis and liver abscess
Entamoeba histolytica
The quadrinucleate cyst is resistant to
____________ and __________
gastric acidity, desiccation
Trophozoites have the ability to colonize
and/or invade the ___________, while cysts are never found within invaded ________.
large bowel, tissues
E. histolytica trophozoites multiply by ___________.
binary fission
They encyst producing uninucleate cysts, which then undergo two successive nuclear divisions to form the characteristic ______________________
quadrinucleate cysts
nuclear-encoded mitochondrial genes
pyridine nucleotide transhydrogenase and hsp60
most common extra-intestinal form of amebiasis.
Amebic liver abscess (ALA)
cardinal manifestations of ALA
fever and right upper quadrant (RUQ) pain
The most serious complication of amebic
colitis is
perforation and secondary bacterial peritonitis
activated macrophages produce _______________ which was lethal to trophozoites.
nitric oxide (NO)
The standard method of parasitologic
diagnosis is microscopic__________________________.
detection of the trophozoites and cysts in stool specimens
Stool culture using _____________________is
more sensitive than stool microscopy, but is not routinely available.
Robinson’s and Inoki medium
gold standard
ELISA & PCR
____________ is the drug of choice
for the treatment of invasive amebiasis
Metronidazole
____________________ of liver abscess is
indicated for patients who do not respond
to metronidazole and who need prompt
symptomatic relief of severe pain
Percutaneous drainage
