PATHOGENIC & NON PATHOGENIC INTESTINAL AMOEBA

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Amibe=

AMEBAE

are structurally simple protozoans which have no fixed shape

SARCOMASTIGOPHORA

They are classified under Phylum:

SARCODINA

They are classified under Subphylum:

RHIZOPODA

They are classified under Superclass:

AMEBIDA

They are classified under Order:

ECTOPLASM, ENDOPLASM

1he cytoplasm of ameba is bounded by a membrane and can be differentiated into OUTER ( ____________) and INNER (_________)

PSEUDOPODIA

are formed by the ameba by thrusting out ectoplasm, followed by endoplasm. These are employed for locomotion and engulfment of food by phagocytosis.

FISSION AND BUDDING

AMEBA Reproduction occurs by

CYST

is formed in unfavorable conditions and is usually the infective form for vertebrate host

FREE-LIVING OR INTESTINAL AMEBAE

Amebae are classified as either ____________________ OR _____________________

NAEGLERIA AND ACANTHAMOEBA

A few of the free-living amebae occasionally act as human pathogens producing meningoencephalitis and other infections such as _________________ and _______________

ALIMENTARY CANAL

The parasitic amebae inhabits in _____________ __________

E. histolytica or Entamoeba histolytica

all intestinal amebae are nonpathogenic except for _____________ ____________

oppurtunistic

All free-living amebae are ____________ pathogens

E. histolytica

was discovered by Losch in 1875, wh o demonstrated me parasite in the dysenteric feces of a patient in St. Petersburg in Russia.

E. histolytica

is worldwide in prevalence, being m uch more common in the tropics than elsewhe re. It has been found wherever sanitation is poor, in all climatic zones from Alaska (61°N) to Straits of Magellan (52°S)

10, 50

lt has been reported that about __% of world population and _% of the inhabitants of developing countries may be infected with the parasite.

E. histolytica

It is the third leading parasitic cause of mortality, after mala ria and schislosomiasis.

TROPHOZOITE, PRECYST, CYST

E. histolytica occurs in three forms

TROPHOZOITE

It is irregular in shape and varies in size from 12- 60 µm; average being 20 micron

TROPHOZOITE

It is large and actively motile in freshly-passed dysenteric stool, while smaller in convalescents and carriers.

MINUTA FORM

The parasite, as it occurs free in the lumen as a commensal is generally smaller in size, about 15-20 µm and has been called the ___________

PSEUDOPODIA

a are finger-like projections formed by sudden jerky movements of ectoplasm in one direction, followed by the streaming in of the whole endoplasm

CRAWLING OR GLIDING MOVEMENT

Typical ameboid motility is a ___________or ___________________ and not a free swimming one. The direction of movement may be changed suddenly, with another pseudopodium being formed at a different site, when the whole cytoplasm flows in the direction of the new pseudopodium. T

LOW

Pseudopodia formation and motility are inhibited at ___temperatures

LININ NETWORK

fine radiating fibrils is called

CARTWHEEL

Nucleus is spherical 4- 6 µm in size and contains central karyosome, surrounded by clear halo and anchored to the nuclear membrane by fine radiating fibrils called the Linin network, giving a _________________ appearance

IRON HEMATOXYLIN

The nucleus is not clearly seen in the living trophozoites, but can be clearly demonstrated in preparations stained with

BINARY FISSION, 8

The trophozoites divide by _______ ________in every _ hours

CYST

Is spherical in shape about 10-20 µmin size

DEEP BLUE OR BLACK

With iron hematoxylin stain, nuclear chromatin and chromatoid bodies appear

GOLDEN BROWN

When stained with iodine, the glycogen mass appears

MATURE QUARDINUCLEATE CYST

INFECTIVE FORM OF E. histolytica

FECAL/ORAL ROUTE

E. histolytica mode of transmission

EXCYSTATION

When the cyst reaches cecum or lower part of the ileum, due to the alkaline medium, the cyst wall is damaged by trypsin, leading to ____________

8 NUCLEI OR EIGHT NUCLEI

The nuclei in the metacyst immediately undergo division to form_____________

SMALL INTESTINE

if excystation takes place in the________ ____________, the metacystic trophozoites do not colonize there, but are carried to the cecum

CECUM, COLON

The optimal habitat for the metacystic trophozoite is the submucosal tissue of __________ and ___________, where they lodge in the glandular crypts and grow by binary fission (

AMEBIASIS

E. hislolytica causes intestinal and extraintestinal _________

AMEBIC ULCER

is the typical lesion seen in intestinal amebiasis (Fig. 3). The ulcers are multiple and are confined to the colon, being most numerous in the cecum and next in the sigmoidorectal region. the intervening mucous membrane between the ulcers remains healthy

FLASK-SHAPED

The typical amebic ulcer is ______-______in cross section, with mouth and neck being narrow and base large and rounded.

AMEBOMA

Occasionally, a granulomatous pseudotumoral growth may develop on the intestinal wall by rapid invasion from a chronic ulcer. This amebic granuloma or ameboma may be mistaken for are malignant tumor.

HEPATIC AMEBIASIS

the most common exctraintestinal complication of amebiasis.

PULMONARY AMEBIASIS

Very rarely, primary amebiasis of the lung may occur by direct hematogenous spread from the colon bypassing the liver, but it most often follow extension of hepatic abscess through the diaphragm and therefore, the lower part of the right lung is the usual area affected

METASTATIC AMEBIASIS

Involvement of distant organs is by hematogenous spread and through lymphatics. Abscesses in kidney, brain, spleen and adrenals have been noticed. Spread to brain leads to severe destruction of brain tissue and is fatal.

CUTANEOUS AMEBIASIS

It occurs by direct extension around anus, colostomy site, or discharging sin uses from amebic abscesses. Extensive gangrenous destruction of the skin occurs. The lesion may be mistaken for condyloma or epithelioma.

GENITOURINARY AMEBIASIS

The prepuce and glans a re affected in penile amebiasis which is acquired through anal intercourse. Similar lesions in females may occur on vulva, vagina, or cervix by spread from perineum. The destructive ulcerative le ions resemble carcinoma

E. coli or Entamoeba Coli

was first described by Lewis (1870) and Cunningham {1871) in Kolkata and its presence in healthy persons was reported by Grassi (1878).

Entamoeba coli or E. coli

• It is worldwide in distribution and a nonpathogenic commensal intestinal ameba.

• It is larger than£. histolytica about 20-50 µm with sluggish motility and contains ingested bacteria but no red cells.

E. hartmanni or Entamoeba hartmanni

occurs wherever E. histolytica is found. le is now considered ro be a separate species of nonparhogenic commensal intestinal ameba.

Entamoeba coli or E. coli

• the nucleus is clearly visible in unstained films and has a large eccentric karyosome and thick nuclear membrane lined with coarse granules of chromatin (Figs 8A and B).

• Cysts are large, 10- 30 µm in size, with a prominent glycogen mass in the early stage. The chromatoid bodies are splinter-Like and irregular. The mature cyst has eight nuclei (Fig. 8C).

• The life cycle is the same as in E. histolytica except that it remains a luminal commensal without tissue invasion and is nonpathogenic.

E. hartmanni or Entamoeba hartmanni

• it is much smaller than E. histolytica, the trophozoirc measuring 4- 12 µm and cyst 5-10 µmin size (Fig. 9).

• Trophozoites do nor ingest red cells and their motility is less vigorous.

• the cyst resembles that of Endolimax nana.

E. gingivalis or Entamoeba gingivalis

was the first ameba of humans, discovered by Gros in 1849

E. gingivalis or Entamoeba gingivalis

• It is global in distribution.

• Only the trophozoite is found; the cystic stage being apparently absent.

• The trophozoite is about 10-20 µm, actively motile with multiple pseudopodia.

E. gingivalis or Entamoeba gingivalis

have been found in bronchial washings and vaginal and cervical smears, where it can be mistaken for E. histolytica.

Endolimax nana or E. nana

This common commensal ameba is widely distributed.

Endolimax nana or E. nana

• It lives in the human intestine

• The trophozoite is small, less than 10 µmin size with a sluggish motility

• The nucleus has conspicuous karyosome connected to nuclear membrane by one or none coarse strands.

Endolimax nana or E. nana

• The cyst is small, oval and quadrinucleated with glycogen mass and chromidial bars, which are inconspicuous or absent (Fig. 108).

• It is nonpathogenic.

Iodamoeba Butschlii

This is widely distributed, though less common than E. coli and E. nana

Iodamoeba Butschlii

• The trophozoite is small, 6- 12 µm, with conspicuous nucleus

• The prominent karyosome is half the size of the nucleus, having bull's eye appearance.

Iodamoeba Butschlii

• The cyst is oval, uninucleate and has a prominent iodine staining glycogen mass (iodophilic body). Hence, the name lodamoeba. It is nonpathogen.ic