PROTOZOANS: INTESTINAL AMOEBA

combined set of all amoeba

Balamuthia mandrillaris

• Agent of GAE

• Free-living amoeba/leptomyxid amoeba

• relatively uncommon

• Does not possess spiky pseudopodia unlike Acanthemoeba

Sappinia spp.

Rarely isolate from human specimens

Blastocystis hominis

• classified as a stramenopile

• has four (4) forms

Vacuolated

Ameboid

Granular

Multiple fission

Four (4) forms of Blastocystis hominis

Vacuolated

• spherical and variable in size (5-20um)

• central clear area and 2-4 peripheral nuclei

Cyst

Infective stage of Blastocystis hominis

Acanthamoeba spp.

• Ubiquitous organism

• Free-living amoeba with trophozoites and cyst stages

Acanthapodia

spiny filaments for locomotion

Skin ulceration

Traumatic penetration

Nasal

Mode of Transmissions for Acanthamoeba spp.

Trophozoites

Infective stage for Acanthamoeba

Acanthamoeba castellani

Acanthamoeba culbertosii

Acanthamoeba polyphaga

Acanthamoeba astronyxis

Acanthamoeba spp.

Acanthemoeba keratitis

chronic infection of the cornea

Granulomatous amoebic meningoencephalitis (GAE)

Acanthamoeba keratitis

Pathology of Acanthamoeba spp.

Corneal Transplant

Antimicrobial drugs (Bigunides, Diamidines)

Treatment for Acanthamoeba spp.

Naegleria fowleri

• “Brain-eating amoeba”

• Heat-loving (thermophilic)

• Trophozoites”

• size: 10-35um

• Karyosome: large, round, centrally located

Flagellated forms

If Naegleria fowleri’s trophozoite is exposed to warm distilled water, it will covert to:

1-2 hours

How many hours does it take to convert the flagellated form of Naegleria fowleri’s trophozoites?

Primary Amoebic Meningoencphalitis (PAM)

Pathology of Naegleria fowleri

Warm freshwater lakes

Where does Naegleria fowleri resides?

Presence of trophozoites in brain and CSF

Post morten analysis

Diagnosis for Naegleria fowleri

0.5% agar

1.5% NaCl

pH 6.6-7.0

When culture is used in Naegleria fowleri, it must be performed on non-nutrient agar plates that contains:

108 F / 42 C

Upon initial screening for N. fowleri, the plate must be incubating with high temperature temparature

Amphotericin B

Treament for Endolimax nana

Entamoeba Polecki

• Zoonotic transmission through pigs and monkeys

• Trophozoites: Resembles E.coli of motility

Papua New Guinea

most common intestinal amoeba in humans

Entamoeba chattoni

• morphologically identical to E. polecki

• Nonpathogenic

Single nucleus

Numbers of nucleus/nuclei present in E. polecki

Angular and Pointed

Chromatoidal materials of E. polecki that resembles E. histolytica

Iodamoeba Buetschlii

• trophozoites:

• size: 9-14um

• motility: sluggish, non-progressive (hyaline pseudopodia)

• centrally located kayrosome

Achromatic granules

Does color in stain

Reddish brown

In Iodamoeba buetschlii, the color in appears with iodine-stained wet mounts

Iodine-stained wet mount

In Iodamoeba buetschlii, stain that makes it reddish brown

Endolimax nana

• “Most common of the smaller intestinal amoeba”

• Cross-eyed cyst

• Trophozoite size: 5-12um

Triangular

Shape of nuclei of Endolimax nana

Clear halo / Karyolymph space

It surrounds the karyosome and extends to the nuclear membrane

4 nuclei

Number of nuclei of Endolimax nana

Blot-like

Cyst of Endolimax nana is large _____ eccentric karyosome

Entamoeba gingivalis

contains ingested leukocytes/WBC

Pyorrheal / Periodontal pockets

In E. gingivalis, isolates are often found in:

Teeth

Gums

Tonsillar crypts

In E. gingivalis, isolates are often found in Pyorrheal / Periodontal pockets between:

Bronchial mucus

Sputum

In E. gingivalis, it has been reported to multiply and appear in:

Entamoeba gingivalis

• associated with oral oral hygiene

• trophozoites: 5-15um in diameter

• Lobose pseudopodia

• Mononucleated with centrally located karyosome

No Cyst stage

In terms of stage, what stage E. gingivalis does not have?

Entamoeba coli

ingests bacteria

Entamoeba coli

• Trophozoites: 15-50um

• Cytoplasm: ingested bacteria, yeast, many more…

• irregular peripheral chromatin with large eccentric nucleus

• blunt pseudopodia (sluggish, nondirectional)

Sluggish

Nondirectional

Characteristics for pseudopodia/pseudopods of E. coli

16-32

Hypernucleated forms of nuclei of E. coli

1-8 nuclei

Numbers of nuclei present in E. coli

Entamoeba Dispar

Entamoeba Moshkovskii

• morphologically identical to E. histolytica

• Non-invasive

• Indistinguishable alone using DFS

Entamoeba Hartmanni

• morphologically identical to E. histolytica, dispar and moshkovskii

• smaller than E. histolytica

• non-pathogenic

• Trophozoites: 3-12um

• Cyst: 4-10um in diameter

Entamoeba Hartmanni

Ingests bacteria

Small race Entamoeba histolytica

other name/term for E. hartmanni

Phylum Sarcomastigophora

Parasites includes Amoeba and Flagellates

Amoeba

• Subphylum Sarcodina

• Presence of pseudopodia (foot-like projections)

Flagellates

• Saubphylum Mastigophora

• Presence of whip-like flagella

Entamoeba

Naegleria

Acanthamoeba

Important Amoeba in Humans

Entamoeba coli

Entamoeba hartmani

Entamoeba dispar

Entamoeba moshkovskii

Entamoeba gingivalis

Commensal Amoeba

Entamoeba histolytica

Pathogenic Amoeba

Entamoeba polecki

Zoonotic Amoeba

Naegleria

Acanthamoeba

Free Living Amoeba

Entamoeba gingivalis

All entamoeba are lumen-dwelling protozoans except:

Entamoeba histolytica

All entamoeba are non-pathogenic except for:

Entamoeba gingivalis

All entamoeba has Cystic stage as their infective stage except for:

Entamoeba

Endolimax

Iodamoeba

3 Genera

Entamoeba

characterized by the presence of chromatin on the nuclear membrane

Cyst

Infective stage of Entamoeba

Trophozoites

Vegetative/reproductive stage of Entamoeba

Entamoeba histolytica

• most invasive

• 3rd most important parasitic disease

• 2nd cause of mortality among parasitic protozoans

Entamoeba histolytica

It ingests RBC

GalNac Lectin

Cysteine Proteinase

Amebapore

Virulence factors of E. histolytica

Entameoba histolytica Trophozoite

• size: 12-60um

• motility: progressive and directional movement

• unstained nuclei are not visible

• Karyosome is small and is often centrally located

• Cytoplasm is finely granular

Hematophagos trophozoites

• Trophozoites with ingested RBC

• Motile forms of Entamoeba histolytica

Trophozoites

What is larger? (Cyst or Trophozoites)

Hematoxylin stain

Trichome stain

Stains used for E. histolytica

Hematoxylin stain

• Cytoplasm: grayish

• Nuclear Membrane: bluish-black

• RBC Inclusion - pale

(for trophozoites)

Trichome stain

• Cytoplasm: green

• Nuclear Membrane: dark red

• RBC Inclusion - cherry red or green

(for trophozoites)

Swiss Cheese appearance of vacuoles

Degenerative stage of E. histolytica

Entameoba histolytica cyst

• size: 10-20um

• spherical

• Nuclei: Quadrinucleated (1-2-4)

• refractile cyst wall

• Cytoplasm: glycogen vacuoles, chromatic bodies, blunted or rounded ends

• cigar-shaped

4

• maximum of the nuclei of E. histolytica

• Mature quadrinucleutal cysts

Hematoxylin stain

• Chromatoidal bars: bluish-black stain

(cysts)

Trichome stain

• Chromatoidal bars- bright red

(cyst)

Amoebic dysentery

Severe amoebic colitis

Explosive daily liquid stools

Tenesmus

Mild Leukocystis

Flask-shaped ulceration

Pathogenesis (Intestinal) of E. histolytica

Amoebic dysentery

• invasive

• presence of blood and mucus in stool

Severe amoebic colitis

• steroid

• severely burned patient

Tenesmus

• painful spasms of the an@l sphinchter (rectal ulceration)

Mild Leukocystis

• WBC count: 12,000/uL but nnot higher than 16,000-20,000/uL

Direct Fecal Smear (DFS)

Antigen-Antibody Detection

Molecular Diagnosis

Liver Scan

Tissue Examination

Diagnosis for E. histolytica

DFS

presence of RBC in trophozoites and cyst in stool

IHA (Indirect Hybridization Assay)

ELISA (Enzyme-Linked Immuno Sorbent Assay)

EIA (Enzyme Immuno Assay)

Antigen-Antibody Detection for E. histolytica

PCR / Thermocycler

Equipment used for Molecular diagnosis for E. histolytica

Period Acid Schiff

Tissue examination where trophozoites appear bright pink in green-blue background

H&E Stain

Tissue examination that allow accurate demonstration of trophozoites

Southeast Asia

Africa

Central and South America

E. histolytica is mostly prevalent to these countries:

Non-invasive

Invasive

Intestinal Manifestations of E. histolytica

Non-invasive

Intestinal manifestation of E. histolytica where it just stays in the intestine

Invasive

Intestinal manifestation of E. histolytica where ulceration of intestinal walls occures

Metronidazole

First line of drug in the treatment of E. histolytica

Metronidazole

Tinidazole

Treatment of choice / drugs for E. histolytica