number of protozoa in the ameba group inhabit human gastrointestinal tract but are not believed to cause significant disease and are often referred to as the nonpathogenic amebas. These include Entamoeba coli, Entamoeba hartmanni, Entamoeba polecki, Entamoeba gingivalis, Endolimax nana, and Iodamoeba butschli
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Non-pathogenic Amoeba. protozoa in the ameba group inhabit human gastrointestinal tract pptx
1. Several species of amebae are capable of colonizing the human gastrointestinal
tract but, in contrast to Entamoeba histolytica, are not considered pathogenic.
The nonpathogenic intestinal amebae include several Entamoeba species (E. coli,
E. hartmanni, and E. polecki), Endolimax nana, and Iodamoeba buetschlii (=I.
bütschlii).
Non- pathogenic amoebae
3. Entamoeba
coli
• Entamoeba coli is a non-pathogenic species of
Entamoeba that frequently exists as a commensal
parasite in the human gastrointestinal tract. E. coli is
important in medicine because it can be confused
during microscopic examination of stained stool
specimens with the pathogenic Entamoeba
histolytica.
4. Trophozoites
• Measure between 18 to 27μm.
• Some trophozoites may be as small as 12μm,
whereas others may be as large as 55μm.
• Equipped with blunt pseudopods.
• Exhibits sluggish, nonprogressive motility.
5. Cysts
• Vary in size from 8 to 35μm and average of 12 to
25μm.
• Thick cell wall surrounds the round to spherical cyst.
• One to eight nuclei with the typical nuclear features
may be seen in unstained as well as as stained
preparations.
6.
7. Life Cycle
• Cysts are typically found in formed stool, whereas
trophozoites are typically found in diarrheal stool.
Intestinal colonization with nonpathogenic amebae
occurs after ingestion of mature cysts in fecally
contaminated food, water, or fomites.
• Excystation occurs in the small intestine
• and trophozoites are released, which migrate to the
large intestine. The trophozoites multiply by binary
fission and produce cysts, and both stages are passed
in the feces
12. Entamoeba
gingivalis
• Entamoeba gingivalis is a non-pathogenic
ameba that inhabits the human oral cavity
and occasionally other sites. Although it is
often found in conjunction with periodontal
disease, no causative association has been
definitively identified.
13. Trophozoites
• Measure 10-20 µm.
• Possess a single nucleus that contains a small, centrally-
located karyosome and fine peripheral chromatin.
• The cytoplasm often contains ingested leukocytes,
bacteria and other debris, very rarely red blood cells.
• The trophozoites may also extend agranular pseudopodia
while the main cell cytoplasm remains granular in
appearance.
• Living specimens can move quickly.
15. Life Cycle
• Trophozoites live in the oral cavity of humans,
residing in the gingival pockets near the base of
the teeth.
• They are not considered pathogenic, and feed
on bacteria and other debris. Trophozoites are
transmitted person-to-person orally by kissing
or fomites (such as eating utensils) .
• The trophozoite stage of E. gingivalis is
morphologically similar to that of E.
histolytica.
• The two should be differentiated, as both can be
coughed up in sputum specimens (if E.
histolytica is present in pulmonary abscesses).
16. Clinical
Symptoms
• Infections of E. gingivalis occurring in the mouth
and in the genital tract typically produce no
symptoms.
• Nonpathogenic E. gingivalis trophozoites are
frequently recovered in patients suffering from
pyorrhea alveolaris.
• It appears that the trophozoites thrive under
disease conditions but do not produce symptoms
of their own.
17. Laboratory
Diagnosis
• An accurate diagnosis of E. gingivalis
trophozoites may be best made by
mouth scrapings, particularly from the
gingival area.
18. Treatment
• Treatment of E. gingivalis is typically
not indicated because the organism is
generally considered a nonpathogen.
20. Endolimax
nana
• Endolimax is a genus of amoebozoa that are found in the
intestines of various animals, including the species E. nana
found in humans. Originally thought to be non-pathogenic,
studies suggest it can cause intermittent or chronic diarrhea.
Additionally, it is very significant in medicine because it
can provide false positives for other tests, notably the
similar species Entamoeba histolytica, the pathogen
responsible for amoebic dysentery, and because its presence
indicates the host has consumed fecal material.
21. Trophozoites
• Vary in size from 5 to 12μm.
• The average trophozoite size range is 7 to 10μm.
• Sluggish, nonprogressive motility, which is accomplished by
blunt, hyaline pseudopods.
• Single nucleus may or may not be visible in unstained
preparations.
• Karyosome is large and irregularly shaped.
• Blotlike appearance.
22. Cysts
• Spherical, ovoid, or ellipsoid cysts
• Measures 7 to 10μm in size.
• Some cysts may measure a mere 4μm,
whereas others may be as large as 12μm.
• There may be one to four nuclei in an E.
nana cyst, the most commonly seen form is
the mature cyst that contains 4 nuclei.
23.
24. Life Cycle
• Cysts are typically found in formed stool,
whereas trophozoites are typically found in
diarrheal stool. Intestinal colonization with
nonpathogenic amebae occurs after ingestion of
mature cysts in fecally contaminated food, water,
or fomites.
• Excystation occurs in the small intestine
• and trophozoites are released, which migrate to
the large intestine. The trophozoites multiply by
binary fission and produce cysts, and both stages
are passed in the feces
29. Entamoeba polecki
• Entamoeba polecki is an intestinal parasite of the genus Entamoeba. E. polecki
is found primarily in pigs and monkeys and is largely considered non-
pathogenic in humans, although there have been some reports regarding
symptomatic infections of humans
30. Trophozoites
• Trophozoites may vary in size, however, ranging from 8 to 25μm.
• Measures 12 to 20μm.
• Sluggish, non progressive motility is
observed in stools of normal consistency.
• In diarrheal stools, trophozoites exhibit progressive, unidirectional
motility.
31. Cysts
• Range in size from 10 to 20μm, the average is
12 to 18μm.
• Spherical to oval.
• Contain one nucleus.
• The nucleus consists of a small central
karyosome.
32. Life Cycle
• There are two stages in the life cycle of E. polecki.
• The first is as a trophozoite, a vegetative stage that cannot survive in the
environment.
• The second is a cyst, where transmission of parasite is possible and provides
protection to harsh external environments. Cysts are infective when ingested by
another organism.
• The cystic form of this protozoan has a diameter as small as 9.5 µm and as large
as
17.5 µm.
• Morphologically, E. polecki is extremely similar to Entamoeba histolytica and
Entamoeba hartmanni.
33. Laboratory Diagnosis
• The trophozoites and cysts of E. polecki may be diagnosed by examining stool
samples.
34. Clinical
Sympoms
• Most patients with E. polecki are
asymptomatic. The only documented
discomfort associated with symptomatic
patients is diarrhea.
35. Treatment
• A combination of metronidazole and
diloxanide furoate has successfully treated
patients with E. polecki. Metronidazole
alone has also been effective.
37. Entamoeba
hartmanni
• Entamoeba hartmanni is a non-
pathogenic amoeba with worldwide
distribution. Its life cycle is similar to
that of E. histolytica but it does not
have an invasive stage and does not
ingest red blood cells
38. Trophozoites
• Measures a mere 8 to 12μm, with a size range
of 5 to 15μm.
• Finger-shaped pseudopods exhibiting
nonprogressive motility are standard.
• Contain one nucleus.
• Peripheral chromatin is usually present.
39. Cysts
• Range in size from 5 to 12μm,
with an average size of 7 to 9μm.
• The spherical cysts may have
one, two, three, or four nuclei.
40. Life Cycle
• Cysts are typically found in formed stool, whereas trophozoites
are typically found in diarrheal stool. Intestinal colonization with
nonpathogenic amebae occurs after ingestion of mature cysts in
fecally contaminated food, water, or fomites.
• Excystation occurs in the small intestine
• and trophozoites are released, which migrate to the large
intestine. The trophozoites multiply by binary fission and
produce cysts, and both stages are passed in the feces
43. Treatment
• Although some questions exist regarding
the pathogenicity of E. hartmanni, it is
generally considered a nonpathogen and
treatment is usually not indicated.
