[07.32] Giardia and Non-Entamoeba Intestinal Protozoans V2.1.pdf

Cyst

What is the dormant and highly resistant life stage found in most protozoans?

Trophozoite

What is the actively feeding, motile, and more vulnerable life stage of protozoans?

Enterocytes

Which cell type is the predominant constituent of the human intestinal tract?

Differentiation

What process do epithelial cells undergo as they migrate up the intestinal crypt?

Absorption and secretion

What are the two primary acquired functions of differentiated enterocytes?

Brush border

What dense, well-ordered structure is formed by the microvilli at the apical end of enterocytes?

Goblet cells

Which intestinal cells are responsible for secreting mucus?

Enteroendocrine cells

Which cell type in the human intestinal tract is responsible for secreting peptide hormones?

Paneth cells

Which cells in the intestinal tract contain antimicrobial peptides (AMPs) and proteins?

Junctions

What structures assume the barrier function of the polarized epithelial cell assembly?

Mucins

What substance coats the epithelial surface to act as a physico-chemical barrier against pathogens?

Lumen

In what specific part of the intestine do commensal organisms typically reside?

Giardia lamblia

Which common intestinal protozoan is also known as the "Kite" or "Old-Man" protozoan?

Mastigophora

Under older taxonomic classification, to which group did Giardia belong due to its flagella?

Four pairs

How many pairs of external flagella does a Giardia lamblia trophozoite possess?

Adhesive disc

What ventral structure does Giardia lamblia use to attach to the intestinal mucosa?

Two

How many distinct nuclei are found in a Giardia lamblia trophozoite?

Teardrop or Kite

What is the characteristic shape of a Giardia lamblia trophozoite?

Up to four

How many nuclei can be present in a mature Giardia lamblia cyst?

Oval

What is the characteristic shape of a Giardia lamblia cyst?

Axonemes

What internal structures are prominently visible in the median of a Giardia lamblia cyst?

Waterborne

In most cases, what type of transmission characterizes giardiasis?

Stomach acid

What substance in the gastrointestinal tract breaks down the cyst walls of Giardia?

Excystation

What is the process of a cyst releasing trophozoites upon reaching the intestines called?

Two

How many trophozoites are released from a single Giardia lamblia cyst?

Binary fission

By what method do Giardia trophozoites multiply in the intestines?

Duodenum or proximal jejunum

In which specific parts of the small intestine do Giardia trophozoites typically attach?

Encystation

What is the process called when trophozoites transform back into cysts, usually in the colon?

Attachment, Activation, Apoptosis (AAA)

What mnemonic describes the three steps of Giardia pathogenesis?

Lectins and Annexins

Interactions with which two types of proteins help facilitate Giardia attachment?

Shortening and destruction

What effect does Giardia attachment have on the microvilli of the enterocyte brush border?

CD8 T-lymphocytes

The activation of which cytotoxic immune cells leads to the rupture of intestinal tight junctions?

Secretory Immunoglobulin A (sIgA)

Which specific antibody type is responsible for the expulsion of Giardia trophozoites?

Nitric Oxide

What substance secreted by the host inhibits trophozoite proliferation and promotes peristalsis?

Cysteine proteases

What are the major virulence factors of Giardia responsible for disrupting tight junctions and depleting mucus?

Arginine

Competition for which amino acid allows Giardia to reduce the host's nitric oxide production?

Variant Surface Proteins (VSPs)

Giardia escapes the immune response by expressing different types of what?

Non-invasive

Is Giardia lamblia generally classified as an invasive or non-invasive parasite?

Chronic carriers

What term describes the 15% of patients who shed infective cysts for more than 6 months without symptoms?

Water loss

Weight loss during acute giardiasis is most likely attributed to what?

Steatorrhea

What term describes the fatty or foul-smelling stools seen in symptomatic giardiasis?

Two weeks

What is the average duration of a self-limiting acute case of giardiasis?

Malabsorption

Chronic giardiasis is primarily characterized by the development of what symptoms?

Stunting and malnutrition

What are two major complications of chronic giardiasis in young patients?

Acquired lactose intolerance

What complication develops in approximately 40% of giardiasis cases?

Falling leaf

What characteristic motility is exhibited by live Giardia trophozoites during stool microscopy?

Direct fecal smear

What is the standard microscopic visualization method for Giardia from fresh stool?

Stool concentration techniques

What can be used to increase diagnostic sensitivity if a direct smear is negative?

Entero-test

Which diagnostic method involves a swallowed capsule used to sample duodenal fluid?

ELISA or PCR

Name two advanced diagnostic tools that provide higher sensitivity than stool microscopy for Giardia.

Nitro-group containing compounds

What general chemical class of drugs is used to treat giardiasis?

Metronidazole

Which nitroimidazole is commonly used as a primary treatment for giardiasis?

Nitazoxanide

Which nitrothiazole is used as a treatment for Giardia?

Albendazole

What drug is used as a second-line treatment for resistant cases of giardiasis?

Low protein diet

What nutritional strategy may be used to starve Giardia trophozoites of arginine?

Balantidium coli

What is the only ciliated protozoan known to infect humans?

200 μm

What is the maximum size Balantidium coli can reach?

Cilia

What structures surround the entire cell membrane of a Balantidium trophozoite?

Kidney-shaped

What is the characteristic shape of the macronucleus in a Balantidium trophozoite?

Cytostome

What structure is used by Balantidium trophozoites to ingest food?

Cyst

What is the circular, infective stage of Balantidium coli?

Pigs

What is the main reservoir host for Balantidium coli?

Small intestine

Where does excystation of Balantidium coli typically occur?

Large intestine and appendix

Which parts of the human digestive tract does Balantidium coli colonize?

Binary fission

How do Balantidium trophozoites replicate?

Hyaluronidase

What enzyme secreted by Balantidium coli degrades the intestinal mucosa to allow invasion?

Rolling

What characteristic motion is exhibited by Balantidium coli trophozoites?

Tetracycline

What is the drug of choice for treating balantidiasis?

Metronidazole or Tinidazole

Name two second-line drugs used for Balantidium coli infection.

Fulminant colitis

Name a severe complication of invasive Balantidium infection.

Sarcocystis hominis

Which intestinal protozoan was previously classified as a fungus and closely resembles Toxoplasma?

Infected meat

How do humans typically acquire Sarcocystis hominis?

Sarcocysts

What structures are formed by invasive Sarcocystis within muscle tissues?

Blastocystis hominis

Which organism was previously classified as yeast but is now recognized as a protozoan?

Vacuolar

Besides the cyst form, which morphological form of Blastocystis is frequently noted?

Metronidazole

What is given as empiric treatment for symptomatic Blastocystis hominis?

Dientamoeba fragilis

Which organism is molecularly reclassified as an amoeboflagellate related to Trichomonas?

Enterobius (Pinworm)

Transmission of Dientamoeba fragilis is hypothetically associated with which other infection?

Pseudopodia

What does Dientamoeba fragilis use for movement?

Intestinal protozoan commensals

What is another name for non-pathogenic intestinal protozoans?

Sentinel organisms

Commensals act as what, signifying potential fecal contamination of food or water?

Endolimax nana

Which commensal cyst contains four small nuclei and a large blot-like karyosome in its trophozoite form?

Iodamoeba buetschlii

Which non-pathogenic protozoan cyst is distinguished by a large glycogen vacuole?

Entamoeba polecki

Which commensal cyst contains a single large nucleus and pleomorphic karyosome?

Entamoeba hartmanni

Which non-pathogenic protozoan looks like a small E. histolytica and is half its size?

Entamoeba coli

Which commensal cyst can contain up to 16 nuclei and an eccentric karyosome?

Hypoalbuminemia

What lab finding in the case study boy likely explained his ascites and pitting edema?

Antral gastritis

What stomach pathology was identified in the case study boy?

Blunting of intestinal villi

What duodenal architecture change was seen in the case study boy?

Albumin transfusion

What treatment was given to the case study boy to address his fluid retention?

Lettuce

Which specific vegetable was found to be most contaminated in the 2022 Philippine study?

73.3%

What percentage of water samples were contaminated with parasites in the Philippine rural farm study?

Paller et al.

Who led the 2022 study on environmental contamination with parasites in the Philippines?

Dormant

Is the cyst form dormant or actively feeding?

Motile

Is the trophozoite form dormant or motile?

Vulnerable

Is the trophozoite form resistant or vulnerable to the environment?

Enterocytes

What is the most predominant epithelial cell type in the intestinal architecture?

Microvilli

What specific structures make up the brush border?

Secretory

What is the primary functional category of Goblet cells?

Hormonal

What is the primary functional category of Enteroendocrine cells?