PARASITOLOGY (PROTOZOAN)

HAYS PLS PAPASARA KO

Entamoeba histolytica

• Pseudopod-forming non flagellated protozoan

• Most invasive

• The only one causes ccolitis and liver abscessin humans, leading to amoebic dysentery.

• Life cycle: INFECTIVE CYST and INVASIVE TROPHOZOITE

• HUMAN is the only host

• Quadrinucleated cyst is resistant to gastric acidity and desiccation and can survive in moist environment.

• Infection occurs when cyst is ingested from fecal contaminated material.

• MOT: FECAL ORAL ROUTE

• Other MOT: VENEREAL TRANSMISSION & DIRECT COLONIC INOCULATION

TROPHOZOITE:

• size: 12um-60um

• karyosome: small and central “bulls eye”

• cytoplamic inclusion: RBC

• multiply via binary fission

• has the ability to colonize/invade large bowels

CYST

• size: 10um-20um

• cytoplamic inclusion: chromatid bars (cigar-shape), glycogen mass (food reserve)

• no. of nuclei: 1-4

DIAGNOSIS

• Microscopic detection of trophozoite and cyst in stool.

• 3 stool specimen will be examined on different days

• Fresh stool must be examined within 30 mins to detect trophozoite via DFS

• METHYLENE BLUE to diffentiate with WBC

• E.histolytica trophozoite with ingested RBC is diagnostic of AMEBIASIS.

• Concentration method: FECT and MIFC are more sensitive than DFS (size of cyst, number of nuclei, location and appearance of the karyosome, the characteristic appearance of chromatoid bodies and presence of cytoplasmic structures like glycogen vacoule).

• STOOL CULTURE: Robinson’s medium

TREATMENT

• TREATMENT OF AMEBIASIS:

  a.) cure invasive disease both intestinal and extraintestinal sites.

  b.) eliminate the passage of cysts from intestinal lumen

• METRONIDAZOLE - drug of choice for invasive amebiasis

• DILOXANIDE FUROATE - for asymptomatic cyst passer

• PERCUTANEOUS DRAINAGE - liver abscess.

Entamoeba moshkovskii

• Free living organism

• First found in sewege

• Able to grow at room temperature (25-30C)

• Osmotolerant (0-41C)

• Morphologically indistinguishable with E.histolytica and E.dispar

• Cyst size: 10um - 20um

• No. of cyst nuclei: 1-4

• Cytoplasmic inclusion of cyst: chromatid bars, glycogen mass

• Trophozoite size: 12um-60um

• Trophozoite karyosome: small, centrally located

• Trophozoite cytoplamic inclusion: ingested bacteria, no RBC

• MOT: Fecal-Oral

• Host: Commensal organism

Entamoeba harmanni (trophozoite sa taas, ubos ang cyst)

• similar to E.histolytica but smaller (3um-12um)

• does not ingest RBC

• Size of cyst: 4um-10um (mature)

• No. of cyst nuclei: 1-4

• Cytoplamic inclusions of cyst: Chromatoid bars (rod-shaped w/ rounded/square ends), diffuse glycogen mass

• Size of trophozoite: 3um-12um

• Trophozoite karyosome: small, centrally or eccentrically

• Cytoplasmic inclusion of trophozoite: Ingested bacteria, no RBC

• MOT: Fecal-Oral

• Host: Commensal organism

Entamoeba coli

• More common than any other human amoebae

• Motility of trophozoite is sluggish

• Can be differentiated by E.histolytica by:

  a.) more vacuolated or granular endoplasm w/bacteria and debris, no RBC

  b.) narrower, less differentiated ectoplasm

  c.) broader and blunter pseudopodia used more for feeding rather locomotion

  d.) more sluggish, unidirected movements

• Cyst size: 10um-35um

• No. of cyst nuclei: 1-8

• Cytoplasmic inclusion of cyst: thin chromatid bars (splintered/pointed ends)

• Size of trophozoite: 15um-50um

• Trophozoite karyosome: Large and irregular, eccentrically located

• Cytoplamic inclusion of trophozoite: vacuoles w/bacteria

• MOT: Fecal-Oral

• Host: Human

Entamoeba polecki

• Found in the intestine of pigs and monkey

• Rarely infects human

• Motility of the trophozoite is sluggish

• E.policki can be distinguishable from E.histolytica by its former cyst is consistently uninucleated, chromatoidal bars are frequently angular or pointed.

• Cyst size: 9um-18um

• No. of nuclei: 1

• Cytoplasmic inclusion cyst: chromatoid bars (angular/pointed), glycogen mass, inclusion mass

• Size of trophozoite: 10um-25um

• Karyosome: small, centrally located

• Cytoplasmic inclusion trophozoite: ingested bacteria and food particles

• MOT: Fecal-Oral

• Host: Monkey and pigs

Entamoeba chattoni

• Found in apes and monkeys

• Morphologically identical to E. polecki

• Rare to infect humans (only 8 cases)

• Identification of E.polecki is done via isoenzyme analysis

• Cyst size: 8um-15um

• No of nuclei: 1

• Cytoplasmic inclusion cyst: similar to E.polecki

• Trophozoite size: 10um-20um

• Karyosome: similar to E.polecki

• Trophozoite Cytoplasmic inclusion: similar to E.polecki

• MOT: Fecal-Oral

• Host: Apes and monkey

Entamoeba gingivalis

• Found in the mouth (oral cavity, lives in the surface of gums and teeth, tonsillar crypts)

• Moves quickly and has numerous of blunt pseudopodia

• NO CYST STAGE

• Abundant cases of oral disease

• Size: 10um-20um

• Karyosome: central and distinct

• Cytoplasmic inclusions: food vacuoles, WBC

• MOT: kissing, droplet spray, sharing of utensils

• Host: humans

Endolimax nana

• Occurs the same frequency as E. coli

• Exhibit sluggish movement

• Have blunt, hyaline pseudopodia, and nucleus has large, irregular karyosome

• Smallest amoeba

• Cyst size: 5um-12um

• No. of nuclei: 1-4 “cross-eyed cyst”

• Trophozoite cytoplasmic inclusion: chromatin granules, diffuse glycogen mass

• Trophozoite size: 5um-12um

• Karyosome: Centrallly located, large and irregular, blot-like appearance

• Cytoplasmic inclusion trophozoite: bacteria

• MOT: Fecal-Oral

• Host: Humans

Iodamoeba butschilii

• Large, vesicular nucleus with a large, central karyosome, surrounded by achromatic granules

• No peripheral chromatin granules on the nuclear membrane.

• Can only be stained by iodine

• Cyst size: 9um-10um

• No. of cyst nuclei: 1

• Cytoplasmic inclusions cyst: absence of chromatoid bars but has large glycogen body which stains dark brown with iodine

• Trophozoite size: 9um-14um

• Karyosome: eccentric, large & central

• Cytoplasmic inclusions trophozoite: bacteria, yeast & other debris

• MOT: Fecal-Oral

• Host: humans

Acanthamoeba spp. (A. trophozoite, B. Cyst)

• Found everywhere, free living amoeba

• Aquatic organism

• Etiologic agent of Acanthamoeba keratitis (AK) and Granulomatous Amebic Encephalitis (GAE).

• Active trophozoite stage with characteristic prominent "thorn-like" appendages

• Highly resilient cyst stage into which it transforms when environmental conditions are not favorable.

• Motile trophozoites feed on gram-negative bacteria, blue-green algae, or yeasts and reproduce by binary fission, but can also adapt to feed on corneal epithelial cells and neurologic tissue through phagocytosis and secretion of lytic enzymes.

• Acanthamoeba trophozoites exhibit a characteristic single large nucleus with a centrally located, densely staining nucleolus, a large endosome; finely granulated cytoplasm; and a large contractile vacuole

• Acanthamoeba has only two stages, cysts and trophozoites

• First described as an opportunistic ocular surface pathogen causing keratitis in 1974.

• Documented as the causative agent of human GAE by Stamm in 1972.

TROPHOZOITE

• 15um – 45um

• With shiny or filiform pseudopodia (acanthopodia)

• “thorn-like” appendages

• Infective stage

• Replicate via mitosis

• MOT: eye, the nasal passages to the lower respiratory tract, or ulcerated or broken skin

• Diagnostic stage

CYST

• 10 um – 12um

• Detectable in tissues

• Double walled – outer wrinkled wall

• Diagnostic stage

Acanthamoeba kerititis

• Associated with the use of improperly disinfected soft contact lenses, particularly those which are rinsed with tap water or contaminated lens solution.

• Immunocompromised state contributes to increased susceptibility to infection

• Symptoms: ocular pain and blurring of vision, corneal ulceration with progressive corneal infiltration may occur.

• Progression leads to scleritis and iritis leading to vision loss

• Diagnosed by epithelial biopsy or corneal scrapings for recoverable amoeba

• Amebae have also been isolated from the contact lens and lens solution of patients

Granulomatous Amebic Encephalitis

• Signs and symptoms: fever, malaise, anorexia

• Neurologic symptoms: increased sleeping time, severe headaches, mental status changes, epilepsy, coma.

• Diagnosis of GAE is usually made post-mortem in most cases.

• Post-mortem gross examinations reveals edematous and soft cerebral hemispheres with areas of hemorrhage and focal abscesses.

• Most common affected areas are posterior fossa structures, thalamus, and brainstem

• Incubation period from initial inoculation is 10 days

• Usually made postmortem in most cases due to the rarity of the disease and its unfamiliarity.

• Recovery of ameba in the CS is exceedingly rare, imaging results are nonspecific

Naegleria spp.

• Free-living protozoan

• Two vegetative forms: an ameba(trophozoite form), and a flagellate (swimming

  form).

• Thermophilic organisms which thrive best in hot springs and other warm aquatic environment

• A dormant cyst form is produced when conditions are not favorable.

• Two forms of trophozoites of Naegleria fowleri: ameboid and ameboflagellate

• Only Naegleria fowleri has been reported to consistently cause disease in humans, although some non-fowleri species may cause opportunistic infections.

Naegleria fowleri (A. Cyst, B. Ameboid, C. Ameboflagellate)

• Has three stages: Cyst, trophozoite, and flagellated form

• Causitive agent of rare Primary Amebic Meningoencephalitis (PAM).

• PAM usually occurs in previously healthy adults with a history of swimming.

• The route of entry is through invasion of organisms through the olfactory bulb after accidental inhalation of water containing the organisms.

• PAM presents as fever, nausea, vomiting, headache, nuchal rigidity, and mental status changes, with rapid progression to coma and death

• Post-mortem examination of infected brain shows hemorrhagic necrosis, particularly of the olfactory bulbs, congestion and edema of neural tissue

• Death usually occurs as a result of cerebral or cerebellar herniation as a result of increased intracranial pressure.

• Most persons infected with Naegleria die prior to institution of effective treatment.

• Symptoms of PAM are indistinguishable from bacterial meningitis.

• Amphotericin B in combination with clotrimazole is synergistic, and has been successfully used to treat PAM.

TROPHOZOITE

• Trophozoite replicate via promitosis

• Trophozoites infect humans or animals by penetrating the nasal mucosa and migrating to the brain via the olfactory nerves.

• Trophozoite are found in cerebrospinal fluid and Tissue

• Measures 10um – 35um

• Rapidly motile

• Two forms:

  a.) Amoeboid – lobate pseudopodia

  b.) Amoeboflagellate – flagella

• Infective stage of N. fowleri

• Diagnostic stage of N. fowleri

CYST

• 7um-15um

• Not detectable in clinical specimens

• Double walled-outer smooth wall

• Not seen in brain tissue