Amoeba - Lobosea

SUBPHYLUM SARCODINA

Entamoeba histolytica

• Direct life cycle

• multiplies by binary fission

• associated diseases:

  • Intestinal amebiasis

  • amebic colitis

  • amebic dysentery

  • EXTRAINTESTINAL AMEBIASIS

• “lyse” tissue destruction

  • 

IS

• CYST

MOT

• ingestion of food/water with cyst

Phoretic Vectors

• cockroach and flies

Location

• Large intestines

MORPHOLOGY

TROPHOZOITES

• 8-65 microns (12-25 microns)

• Motility:

  • progressive

  • finger-like pseudopods

• Nuclei:

  • one

  • Karyosome:

    • small and central

• Peripheral chromatin:

  • fine and evenly distributed

• Cytoplasm:

  • finely granular

• Cytoplasmic inclusion

  • ingested RBCs

• 

CYST

• 8-22 microns (12-18 microns)

  • smaller than trophs

• Shape:

  • spherical to round

• Nuclei:

  • one to four

  • Karyosome:

    • small and central

  • Peripheral chromatin:

    • fine and evenly distributed

• Cytoplasm:

  • finely granular

• Cytoplasmic inclusion

  • Chromatoid bars, rounded ends in young cysts

  • Diffuse glycogen mass in young cysts

• 

Laboratory diagnosis

• Standard and alternative methods

• ELISA (Enzyme-linked immunosorbent assay)

• IHA (indirect hemagglutination)

• GDP (gel diffusion precipitin)

• IIF (indirect immunofluorescence)

Life Cycle

• survival in a feces contaminated environment for up to 1 month is common

• 

Epidemiology

• infection is as many as 10% of the world’s population

• considered a leading cause of parasitic deaths after malaria

Clinical Symptoms

• only known as pathogenic intestinal amoeba

• Asymptomatic

• Symptomatic

Treatment

• Paramomycin

• Diloxanide furoate (Furamide)

• Metronidazoles (Flagyl)

Prevention and Control

• Improved sanitation

  • help reduce the likelihood of transmission

Entamoeba hartmanni

MORPHOLOGY

TROPHOZOITES

• 5-18 microns

• Motility:

  • non-progressive

  • finger-like pseudopods

• Nuclei:

  • one

  • Karyosome:

    • small and central

  • Peripheral chromatin:

    • fine and evenly distributed

• Cytoplasm:

  • finely granular

• Cytoplasmic inclusion

  • ingested bacteria may be present

• 

CYST

• 5-12 microns

  • smaller than trophs

• Shape:

  • spherical

• Nuclei:

  • one to four

  • Karyosome:

    • small and central

• Peripheral chromatin:

  • fine and evenly distributed

• Cytoplasm:

  • finely granular

• Cytoplasmic inclusion

  • Chromatoid bars, rounded ends in young cysts

  • Diffuse glycogen mass in young cysts

• 

Laboratory Diagnosis

• NONPATHOGENIC

• examining the stool

• advisable to not base solely on the sizes of the amoeba as it may mislead results

• ingestion of infected cysts

• ASYMPTOMATIC

Prevention and Control

1. Good sanitation and good hygiene practices

2. Protection of food and water from vectors like flies and cockroaches

Endolimax nana

• NONPATHOGEN

• most common of the smaller intestinal amebae

• usually encountered with about the same frequency as in E. coli

• colonizes the colon

MOT

• Fecal-oral via cyst

MORPHOLOGY

TROPHOZOITES

• 5-12 microns

• Motility:

  • sluggish/slowly

  • nonprogressive

  • blunt pseudopods

  • feeds bacteria and food debris

• Nuclei:

  • one

  • Karyosome:

    • large, irregular, blotlike

• Cytoplasm:

  • granular

  • vacuolated

• Cytoplasmic inclusion

  • bacteria

• 

CYST

• forms as feces dehydrates

• 7-10 microns (4-12 microns)

  • smaller than trophs

• Shape:

  • spherical, ovoid, ellipsoid

• Nuclei:

  • one to four (most common)

  • with large endosomes

  • Karyosome:

    • large

    • blotlike

    • usually central

• Cytoplasm:

  • granular

  • vacuolated

• Cytoplasmic inclusion

  • Chromatin granules

  • Nondescript small mass

  • Diffuse glycogen mass in young cysts

• 

Life Cycle

• Intestine

• organisms passed in feces

• 

Epidemiology

• are with poor hygiene

• substandard sanitary conditions exist

Clinical Symptoms

• Asymptomatic

Prevention and Control

• improved hygiene

• disposal of fecal waste

Laboratory Diagnosis

• examination

• concentration, permanent stained smear

Iodamoeba butschlii

MORPHOLOGY

TROPHOZOITES

• 8-12 microns

• Motility:

  • sluggish/slowly

  • usually progressive

• Nuclei:

  • one

  • Karyosome:

    • large

    • usually central refractive achromatic granules may be present

• Cytoplasm:

  • coarsely granular

  • vacuolated

• Cytoplasmic inclusion

  • bacteria

  • yeast cells, other debris

• 

CYST

• 5-22 microns

• Shape:

  • ovoid, ellisoid, triangular, other shapes

• Nuclei:

  • one

  • Karyosome:

    • large

    • eccentric achromatic granules

      • on one side present

• Cytoplasm:

  • coarsely granular

  • vacuolated

• Cytoplasmic inclusion

  • well defined glycogen mass may be present

• 

Laboratory diagnosis

• Iodine wet preps

  • glycogen picks up the iodine stain

  • remain unstained following trichrome staining

    • aids on identification

Epidemiology

• found worldwide and has higher prevalance in tropical regions

Entamoeba gingivalis

MOT

• mouth-to-mouth (kissing)

• droplet contamination (contaminated drinking utensil)

MORPHOLOGY

TROPHOZOITES

• resemblance to E. histolytica

• 8-12 microns

• Motility:

  • active

  • varying pseudopods appearance

• Nuclei:

  • one

  • Karyosome:

    • centrally located

  • Peripheral chromatin:

    • fine and evenly distributed

  Cytoplasm:

  • finely granular

• Cytoplasmic inclusion

  • leukocytes

  • epithelial cells

  • bacteria

• 

CYST

• UNKNOWN stage

Life Cycle

• lives around the gum line of the teeth in the tartar and gingival pockets of unhealthy mouths

• trophozoites inhabit tonsillar cryps and bronchial mucus

• like E. histolytica— can be found in the sputum and pulmonary abscess

• multiplied by binary fission

• not survive following contact with stomach juices

• also recovered in vaginal and cervical specimen from women using IUD

  • spontaneous disappearance following removal of IUD

Clinicala symptoms

• no symptoms

• recovered in patients suffering from pyorrhea alveolaris

• thrives under disease conditions but do not produce symptoms

Naegleria fowleri

• Causative agent of Primary Amoebic Meningoencephalitis (PAM)

• Thermophilic organisms (up to 30°C)

• Multiplies through promitosis

  • intracellular mitosis

  • nuclear membrane doesn’t break down

• three known morphologic forms

  • ameboid trophozoite

  • flagellate (protozoa) forms

  • cysts

• N. australiensis

  • pathogenic in mice

  • may infect humans

MOT

• Oral and Intranasal

  • while swimming in contaminated lakes, pools, and rivers

  • often migrate in the brain

• inhaling dust infected by N. fowleri

Diagnosis

• Cerebrospinal Fluid (CSF)

  • spinal tap

• Culture

  • non-nutrient medium with Page’s saline seeded with living Escherichia coli

• PCR

• ELISA

MORPHOLOGIC FORMS

CYST

• 9-12 microns

• thick cell walls

• uninucleated w/ rounded chromatoidal bars

TROPHOZOITE

FLAGELLATE

• 7-15 microns

• flagella

  • whiplike structures; locomotion

  • 2 at broad end

• Motility

  • spinning or jerky

• directional

• does not divide

AMOEBOID

• 8-22 microns

• only form recognized in humans

• single pseudopod

• Nucleus

  • one

  • karyosome

    • large central

• without peripheral nuclear chromatin

• broad anterior end; posterior end is tapered

• motility

  • sluggish

  • done by blunt pseudopodia

• cytoplasm

  • granular

  • often contains vacuoles

Epidemiology

• found in warm bodies of water

• contaminated dust

Primary Amebic Meningoencephalitis

• ameboid trophozoites invade the brain causing rapid tissue destruction

• symptoms

  • fever, headache, sore throat, nausea, and vomiting

  • stiff neck and seizures

  • smell and taste alterations and blocked nose

  • Kernig’s sign

    • diagnostic sign for meningitis

    • patient is unable to stretch his/her legs because of hamstring stiffness

• Postmortem brain tissue samples has the typical ameboid trophozoites

Treatment

• always result to death unless detected and treated early

• PROMPT Amphotericin B in combination with rifampin or miconazole

  • damages the cell wall of Naegleria

Prevention and Control

• posting off-limits sign on contaminated water sources

• educating community

• Chlorinate swimming pools and hot tubs

• immediately repairing of possible sources of contamination like cracks

Life Cycle

• replication

  • simple binary fission

• ameboid trophozoites → flagellate trophozoites (after being transferred to water from a tissue culture)

• flagellate trophozoites do not divide but lose flagella and convert back to ameboid

• cyst

  • only exist in external environment

• external environment

  • amebic trophozoites → cysts and flagellates → amebic trophozoites

• human contact

  • swimming in contaminated water

  • enters through

    • nasal mucosa and often migrate to the brain

      • causing rapid tissue destruction

  • inhaling infected dust

Acanthamoeba spp.

• most common

  • A. castellani

MORPHOLOGY

TROPHOZOITES

• 12-45 microns (25 microns)

• Motility

  • sluggish

  • spine-like pseudopods

    • acanthopodia

• Nucleus

  • one

    • Karyosome

      • large

• Cytoplasm

  • granular and vacuolated

CYST

• 8-25 microns

• round-shaped

• double cell wall

• Cytoplasm

  • disorganized

  • granular

Laboratory Diagnosis

• Cerebrospinal Fluid (CSF)

• Brain tissue

• Corneal scrapings

  • infections of the eye

  • may be cultured on non-nutrient agar plates with gram-negative bacteria (E. coli)

    • bacteria as the source of food

    • produce a set of marks (tracks) on the agar

  • histologic examination

    • calcoflour whits

      • primarily used for fungi;

      • stain

• Indirect immunofluorescent antibody staining

Life Cycle

• humans may acquire in one of two ways

1. Aspiration or nasal inhalation

   • Trophozoites enter via lower respiratory tract or through ilcers in the mucosa or skin

   • Hematogenous spread

     • through the bloodstream & invade CNS (serious CNS infections)

2. Direct invasion of the parasite in the eye

   • 2 groups are at risk:

     • contact lens wearers

       • Acanthamoeba keratitis

     • trauma to the cornea

   • contaminated saline

Granulomatous Amebic Encephalitis (GAE)

• Location

  • lungs

  • hematogenous spread to the brain

• CNS Infection

• Symptoms

  • headaches, seizures, stiff neck, nausea, vomiting

• Granulomatous lesions

  • in the brain

  • may contain both Acanthamoeba trophozoites and cysts

• other areas of the body

  • kidneys

  • pancrea

  • prostate

  • uterus

Acanthamoeba keratitis

• infections of the cornea of the eye

• Symptoms

  • severe ocular pain

  • vision problems

• Infected tissue

  • may contain trophozoites and cysts

• perforation of the cornea may result

• subsequent loss of vision

Treatment

• begin treatment immediately

• itraconazole

• ketoconazole

• miconazole

• propamidine isethianate

• rifampin

Prevention and Control

• avoid using homemade non-sterile saline solutions for contact lens

Entamoeba coli

MORPHOLOGY

CYST

• 10-35 microns (usually, 15-25 microns)

• splinter-like chromatoidal bars

• mature cyst with 8 nuclei

  • Peripheral chromatin

    • coarsely granular, may be clumped and unevenly arranged

  • Karyosome

    • large, may or may not be compact and/or eccentric

• Glycogen

  • diffuse, may be absent in mature cysts

• 

TROPHOZOITE

• 15-50 microns (20-25 microns)

• moves in several directions at the same time

• sends out several pseudopods at the same time

• pseudopods trusted out slowly

• Endoplasm

  • contain bacteria, yeasts, and cell detritus

• stained nucleus contains a thicker nuclear membrane with layer of variously sized chromatin granules unevenly distributed along the inside border of nuclear membrane

  • Karyosome:

    • large, eccentrically located

• 

Entamoeba polecki