Download AUF Parasitology - Summary of Amebae and more Assignments Parasitology in PDF only on Docsity!
Cuaresma, Reena Ann S. MTClinPara (Lecture) INTESTINAL AMEBAE Entamoeba histolytica (pathogenic) & Entamoeba dispar (nonpathogenic) DH Infective stage Diagnostic stage Morphology MOT Life Cycle Trophozoite Cyst Man Cyst Cyst & Trophozoite Pseudopodia: Finger-like, explosive pseudopodia Motility: Progressive and active Karyosome: Centrally located, small, unobstructive Shape: Spherical Number of nuclei: 1 to 4 nuclei Shape of chromatoidal body: It has elongated bars with bluntly rounded ends ✔ Eating contaminated food ✔ Drinking contaminated water ✔ Sexual contact 1 – Man (DH) will pass the diagnostic trophozoites and cysts. 2 – The trophozoites encyst in less than a week to become cyst (IS). 3 – Trophozoites disintegrates in the environment and in gastric lumen. 4 – Man will ingest the cyst, exist in small intestine and cause an asymptomatic stage characterized by carriers who release cyst. COMMENSAL AMEBAE Entamoeba coli DH Infective stage Diagnostic stage Morphology MOT Life Cycle Trophozoite Cyst
Man Cyst Cyst & Trophozoite Pseudopodia: Blunt, broad, and short pseudopodia Motility: Sluggish, nonprogressive, with blunt pseudopods Karyosome: Typically big in size, discrete, & eccentric Shape: Spherical or oval shape Number of nuclei: 1 to 8 nuclei Shape of chromatoidal body: Splinter-like chromatoidal bodies with pointed ends ✔ Eating contaminated food ✔ Drinking contaminated water ✔ Sexual contact 1 – Cyst and trophozoites are passed out in feces (DS). 2 – Noninvasive colonization occurs after ingestion of mature cysts in fecal contaminated food, water, or fomites. 3 – Excystation occurs in small intestine. Then, trophozoites are released that eventually migrates to the large intestine. 4 – Trophozoites passed in stool are rapidly destroyed once outside the body. Other Commensal Species Entamoeba moshkovskii • Physiologically unique
- First detected in sewage
- Morphologically ‘indistinguishable’ from E. histolytica and E. dispar, but differs biochemically and genetically
- Osmotolerant – can grow at room temperature (25-30°C)
- Limited pathogenicity in animals
- Nonpathogenic to humans Entamoeba hartmanii • “Small race E. histolytica”
- Found in human intestinal tract but considered as nonpathogenic
- Morphological: Concentrically round with chromatoidal bodies; forms small cyst (with 4 nuclei) Entamoeba polecki • Best known for pigs’ and monkeys’ infections
- MOT: Ingestion of cyst in pigs or monkeys’ feces through contaminated food
- Can also be obtain from: Goats, Sheep, and Cattle (domestic animals) Entamoeba chattoni • Found in apes and monkeys
- Morphologically identical to E. polecki
- Isoenzyme analysis – used in identifying E. chattoni
Iodamoeba buetschlii DH Infective Stage Definitive Stage Morphology MOT Life Cycle Trophozoite Cyst Man Cyst Cyst & Trophozoite Pseudopodia: Short, blunt, broad, slow pseudopodia Motility: Sluggish and nonprogressive Karyosome: Usually centrally located and large. Surrounded by amorphous, refractile granules. Shape: Oval in shape; can be ellipsoidal as well. It has a prominent iodine staining glycogen mass. Number of nuclei: 1 (Uninucleated) Shape of chromatoidal body: No chromatoidal bodies; granules are present on circumstance ✔ Ingestion of mature cysts in fecal contaminated food, water, or fomites 1 – Cyst and trophozoites are passed out in feces (DS). 2 – Noninvasive colonization occurs after ingestion of mature cysts in fecal contaminated food, water, or fomites. 3 – Excystation occurs in small intestine. Then, trophozoites are released that eventually migrates to the large intestine. 4 – Trophozoites passed in stool are rapidly destroyed once outside the body. FREE-LIVING PATHOGENIC AMEBAE Acanthamoeba Species – “Trojan horse of Microbial world” (A. byersi, A. castellani, A. culbertsoni, A. hatchetti, A. healyi, A. astroonyxix, A. divionensis, A. polyphaga) DH Infective stage Diagnostic stage Morphology MOT Life Cycle Trophozoite Cyst Man Trophozoite Cyst & Trophozoite • Single, large nucleus
- Double walled; Outer – wrinkled Inner – polygonal ✔ Penetration of soft, broken, or wounded skin 1 – Active trophozoites are ingest/feeds on bacteria, yeast, and algae.
- Large contractile vacuoles
- Centrally-located nucleolus
- Acanthopodia – spiny filaments of locomotion
- Contains Chitin and beta glucans ✔ Inhalation 2 –^ Enters humans through infective trophozoites via penetration of soft, broken or wounded skin or via nasal passages. Naegleria fowleri DH Infective stage Diagnostic stage Morphology MOT Life Cycle Ameboid Trophozoite Flagellated Trophozoite Cyst Man Ameboid trophozoite Ameboid and flagellated trophozoite
- Lobopodia (lobate pseudopodia)
- Granular cytoplasm with food vacuole
- Nucleus: Has central karyosome but no peripheral chromatin
- Divides via binary fission
- Recognizable in humans only
- Ameboid form in distilled water will transform to this pear-shaped flagellated form
- Has 2 flagella (when flagella are lost, they revert back to ameboid form)
- Motility: Jerky or spinning
- Thick, smooth, double walled cyst
- Nucleus is identical to trophozoite
- Not found in human tissue No cystic stage for humans ✔ Exposure to contaminated water; but it cannot be acquired via drinking contaminated water. ✔ Inhalation during swimming 1 – Free living amoeboid trophozoites in water 2 – Ingest by humans via inhalation (during swimming) 3 – Penetrated the nasal mucosa 4 – Olfactory nerve infection 5 – It can go to brain and progress to primary amoebic meningoencephalitis to death.
PATHOGENIC FLAGELLATES
Giardia duodenalis Other names Diagnostic stage Infective stage Morphology MOT & Disease Life Cycle Trophozoite Cyst
- G. intestinalis
- G. lamblia
- G. enterica
- Cercomonas intestinalis
- Megastomaenterica
- Lamblia intestinalis Cyst Trophozoite Mature Cyst
- “Old man with eyeglasses”
- Falling leaf motility; with 4 pairs of flagella
- Teardrop-shaped; bilaterally symmetrical
- Has axostyle and parabasal bodies
- Has Adhesive disc or Ventral sucking disc - used for attachment to intestine
- Immature – 1 nuclei
- Mature – 4 nuclei
- Has parabasal/ median bodies
- Colorless, smooth cyst wall ✔ Ingestion of contaminated water ✔ Fecal-oral route Disease: Giardiasis / Traveler’s diarrhea 1 – Ingestion of mature cyst in the host’s small intestines (duodenum) 2 – Cyst released trophozoite (excystation) 3 – Trophozoites undergo replication via binary fission 4 – Migrates to large intestine and turn to cyst (encystation) 5 – Cyst will pass out the body in stool. Trichomonas vaginalis Specimen used Diagnostic stage Infective stage Morphology MOT & Disease Life Cycle Trophozoite Cyst
- Urine
- Vaginal discharges
- Urethral discharges
- Prostatic secretions Trophozoite Trophozoite • Has 1 ovoid nucleus - Short undulating membrane None (^) ✔ Sexual transmission Disease: Trichomoniasis (STD) 1 – Trophozoite in vaginal and prostatic secretions and urine 2 – Trophozoite replicate via binary fission
Culture methods that may be used:
- Modified Diamond
- Feinberg- Whittington
- Presence of granules along the axostyle
- Rapid, jerky motility ;
- 4 free anterior flagella
- 1 posterior flagellum embedded in undulating membrane
- Vaginitis
- Urethritis
- Asymptomatic
- Strawberry cervix
- Red lesions, yellowish discharge 3 – Trophozoite in vagina or orifice of urethra OTHER FLAGELLATES (NONPATHOGENIC) Flagellates Diagnostic stage Infective stage Morphology (^) Disease Association Life Cycle Trophozoite Cyst Chilomastix mesnilli Trophozoite Cyst Trophozoite
- Asymmetrically pear-shaped
- Corkscrew motility
- Has 3 anterior flagella
- Has 1 which extend from cytosome
- “ Shepherd’s crook ”
- Spiral groove across its body
- Uninucleated (mature)
- Lemon-shaped or nipple-shaped
- Has clear anterior hyaline knob
- Cytosome Nonpathogenic 1 – Cyst and trophozoite will be passed out on stool. Yet, only cyst can survive. 2 – Ingestion of cysts in contaminated water, food, or via fecal-oral route (MOT). 3 – Migrates to large intestine, and excystation occurs (C → T)
References: Belizario, V. & De Leon, W. (2015). Medical Parasitology in the Philippines. The University of the Philippines Press. Centers for Disease Control and Prevention. (2019, July 31). Non-pathogenic flagellates. https://www.cdc.gov/dpdx/nonpathogenic_flagellates/index.html Centers for Disease Control and Prevention. (2019, October 29). Intestinal (non-pathogenic) amebae. https://www.cdc.gov/dpdx/intestinalamebae/index.html Centers for Disease Control and Prevention. (2019, August 19). Free Living Amebic Infections. https://www.cdc.gov/dpdx/freelivingamebic/index.html#:~:text=Fort%20Worth%2C%20Texas.- ,Laboratory%20Diagnosis,cornea)%20or%20of%20corneal%20scrapings Centers for Disease Control and Prevention. (2019, June 5). Chilomastix mesnili. https://www.cdc.gov/dpdx/chilomastix/index.html Centers for Disease Control and Prevention. (2019, May 3). Dientamoeba fragilis infection. https://www.cdc.gov/dpdx/dientamoeba/index.html Zeibig, E. (2012). Clinical Parasitology: A Practical Approach (2nd ed.). St. Louis: Saunders.
