Chapter 47 - Intestinal Protozoa Flashcards
Intestinal Protozoa:
- Uni/multicellular?
- Pro/eukaryotic?
- How do they multiply?
- Are unicellular eukaryotic organisms.
- Multiply by binary fission.
Amoebae (Sarcodina)
- What do they use for movement?
- (Non)pathogenic?
- Contain pseudopodia (cytoplasmic protrusions).
- Are free living, pathogenic or nonpathogenic
Entamoeba histolytica
- What diseases is this responsible for?
- How is it transmitted?
- Describe the movement.
- Agent of amebic colitis and amebic liver abscess
- Fecal oral route
- Rapid and unidirectional movement
Entamoeba histolytica
- Describe the chromatin arrangement.
- Describe the karyosome.
- Describe the cytoplasm.
- Evenly arranged chromatin on nuclear membrane.
- chromatiodal body/bar in cysts
- Small compact karyosome
- multiple in cysts
- Cytoplasm finely granular
Entamoeba histolytica
- What does it like to eat?
- Red blood cells (RBCs) in cytoplasm
- - *no longer a diagnostic feature of E. histolytica
Entamoeba dispar
- How many of these samples contain ingested RBCs?
- 16% of E. dispar clinical samples contain ingested red blood cells
Entamoeba histolytica
- What stages must be reported?
- How big are members of each stage?
- Must report cysts and/ or trophs
- Size
- Trophs 12-60µm (usual 15-20µm)
- Cysts 10-20µm
Entamoeba histolytica
- What ailments is it responsible for?
- What does it do to the cells/tissues?
- Amebic colitis
- Liver involvement
- Amebic lesions, cell lysis and tissue necrosis.
Entamoeba histolytica
- What is the process by which trophs cause pathogenesis?
- Trophs interact through a series of steps:
- Adhesion to the target cell
- Phagocytosis
- Cytopathic effects
Entamoeba histolytica
- Where does cyst formation occur?
- Cysts formation only occurs in the intestinal tract, infective stage and mode of transmission
Entamoeba histolytica
- What type of immune response does it induce?
- Induces both humoral and cell mediated immune responses
Entamoeba histolytica
- What two classes of drugs are used for treatment?
- Luminal amebicides
- Tissue amebicides
Entamoeba histolytica
- What are four different methods for detection?
- Antigen detection
- Histology
- Nucleic acid–based tests
- Real-time PCR
- Multiplex assays
- Serologic detection
Entamoeba dispar
- what parasite is this morphologically identical to?
- (non)pathogenic?
- E. histolytica and E. dispar are morphologically identical species.
- E. histolytica/E. dispar cysts are spherical and usually measure 12 to 15 μm (range may be 10 to 20 μm).
- nonpathogenic
What are four main features that distinguish E. dispar from Entamoeba coli?
- E. coli (non)pathogenic?
- Entamoeba coli
- Cysts ingested, produce trophs in intestinal tract to excreted infective cysts.
- Trophs larger.
- Chromatoidal bars-splintered
- Mature cyst 8 nuclei
- nonpathogenic
Endolimax nana
- (non)pathogenic?
- Cyst shape?
- nonpathogenic
- cyst is spherical/ovoid in shape
Endolimax nana mature cyst
- size?
- how many nuclei?
- describe the cyst wall.
- Chromatoidal bodies?
- Diameter: 5-15um
- 4 nuclei when mature
- refractile cyst wall
- c. bodies not usually found
Endolimax nana
- size?
- describe the cytoplasm.
- how many nuclei?
- describe the nuclei.
- chromatin?
- describe the pseudopodia.
- motility?
- 6-15um
- cytoplasm is granular and vacuolated
- nucleus (1) has a large, irregularly shaped karyosome that may appear “blot-like”
- no peripheral chromatin on the nuclear membrane
- pseudopodia are blunt and hyaline
- sluggish, non-progressive motility
Iodamoeba butschilii - pathogenic? Trophs: - size? - motility? - describe size and location of karyosome. - describe the cytoplasm. - what is the distinguishing characteristic of the nucleus? Cysts: - size and shape? - how many nuclei?
- nonpathogenic Trophs: - 8-20µm - fairly active motility - Large karyosome, central or eccentric - Vacuolated cytoplasm -- Large glycogen vacuole - Nucleus may appear to have a halo Cysts: - round to oval - 5-20µm - Single nucleus
Blastocystis hominis
- what are the four major forms?
- Cyst (thick- and thin-walled)
- Central vacuole (central body)
- Amoeboid (rare)
- Granular (in culture)
Blastocystis hominis
- What are the symptoms?
- Causes diarrhea, cramps, nausea, fever, and vomiting
Blastocystis hominis
- what are the three most common ways to make a diagnosis?
- Routine stool examination. Quantitate
- Antigen detection using enzyme-linked immunosorbent assays (ELISAs)
- Antibody detection using ELISA and fluorescent antibody tests
Flagellates
- where in the body can they be found?
- What are the four most common and what are their distinguishing characteristics?
- which of those four are considered pathogenic?
- Genera may live in the gastrointestinal tract, bloodstream, or tissues.
- Common species (with characteristics) include:
- Giardia lamblia (sucking disk and axonomes)
- Dientamoeba fragilis
- Chilomastix mesnili (cytostome and spiral groove)
- Pentatrichomonas hominis (undulating membrane)
- G. lamblia and D. fragilis are considered pathogenic
Giardia lamblia (duodenenalis)
- mode of transmission?
- symptoms?
- Is acquired from contaminated food or drink.
- Giardiasis causes diarrhea with no blood, mucus, or exudate.
Giardia lamblia (duodenenalis) Trophs: - shape? - how do they reproduce? - what do they use to attach to their host?
- tear-drop shaped.
- Divide by longitudinal binary fission producing 2 daughter trophozites
- Attach to intestinal epithelium by ventral disk
Giardia lamblia (duodenenalis)
Cysts:
- where in the body to these form?
- what structures to these have that the trophs do not?
- Cysts form as it moves through the jejunum
- median bodies
- axonomes
Giardia lamblia (duodenenalis)
- how common is it?
- what are the subgenotypes and how do they differ?
- Most common cause of intestinal infection worldwide
- Subgenotypes A-B
- Subgenotype B is only isolated from humans
- Subgenotype A is in both animal and humans
Giardia lamblia (duodenenalis)
- what kind of diseases does it cause?
- what is its antigenic variation?
Spectrum of disease - Asymptomatic infection - Intestinal disease - Chronic disease Antigenic variation - Variant-specific surface proteins (VSPs)
Giardia lamblia (duodenenalis) - what are the four most common ways to make a diagnosis?
- Because of attachment may take 5-6 stool specimens
- Antigen detection by:
- ELISA
- Fluorescent methods with monoclonal antibodies
- Immunochromatographic strips
- Histologically
- Nucleic acid–based tests
- Multiplex assays
- xTAG Gastrointestinal Panel
Giardia lamblia (duodenenalis) - what is the treatment?
- Self-limiting
- Metronidazole
- nitrazoxanide
- tinidazole
Dientamoeba fragilis
- How many nuclei in the troph?
- Describe the appearance of the chromatin?
- Vacuoles?
- What is the outstanding feature that sets this apart from other parasites?
- One to two nuclei in trophozoite
- nuclear chromatin is fragmented into 3-5 granules.
- Vacuolated cytoplasm
- NO KNOWN CYST STAGE
Dientamoeba fragilis
- Collection methods?
- Viability/stability?
Collection
- 3 samples
- 24 to 48 hours of viability of trophs
- Have been recovered in formed stool.
Dientamoeba fragilis
- Symptoms?
- Diarrhea
- Abdominal pain
- Nausea
- Poor weight gain
- Eosinophilia
Flagellates: Chilomastix mesnili - pathogenic? - shape of troph? - # of nuclei? - define cytostome.
- Nonpathogenic
- Pear shaped trophozoite
- Single nucleus
- Distinct oral groove(cytostome)
Flagellates:
Chilomastix mesnili
- cyst shape?
what is a feature/demarcation unique to the cyst?
- Cysts pear or lemon shaped
- typical cytostomal fibril (shepherd’s crook)
Ciliates
- What are the types of nuclei seen in this class?
- What is the one pathogen seen in this class?
Two types of nuclei - Macronucleus - Micronucleus- one or more Only one pathogen - Balantidium coli
Balantidium coli
- what animal, aside from humans, is this associated with?
- where does it invade in humans? what does it do?
- pig
- Organism can invade tissues and form ulcers
Balantidium coli
- Morphologic characteristics (troph)
- nuclei
- cytosome
- Morphologic characteristics (cyst)
- nuclei
Troph - Two nuclei -- Macronucleus -- Micronucleus - A cytosome on the anterior pointed end Cyst - two nuclei
Balantidium coli
- cytoplasm?
- diagnosis?
- treatment?
- Cytoplasm with many vacuoles
- Best by direct smear
- Tetracycline
Sporozoa (Apicomplexa)
- multi/unicellular?
- where in the body does it invade?
- 3 classes?
- Unicellular with apical complex
- In the gastrointestinal tract of vertebrates throughout life
Classes - Cyclospora
- Cryptosporidium
- Cystoisospora belli
Cryptosporidium spp. (parvum)
- method of transmission?
- where does it infect?
- Are acquired from contaminated water or infected persons.
- Infect epithelial cells of gastrointestinal tract
Cryptosporidium spp. (parvum)
- life cycle?
- Ingestion of oocysts
- Trophozoite development
- Merogony (asexual amplification)
- Gametogony (sexual differentiation)
- Formation of new oocytes (sporogony)
Life Cycle of Cryptosporidium
- how many sporozoites?
- where do they invade?
- what is the next stage of development?
- cycles of mergonoy?
- next stage of development?
- how many meroizoites?
- next stage of development?
- final stage of development?
- Oocysts releases 4 sporozoites
- Invade epithelial cells
- Develop into Trophs
- 2-3 cycles asexual amplification (Mergonoy)
- Different meronts
- Contain 4-8 merozoites
- Merozoites develop by gametogony
- New sporozoites by sporogony
Cryptosporidium spp
- Extracelular stage?
- Typical age of patient?
- The only extracellular stage is the oocyst.
- Infection of children <5yo.
Cryptosporidium spp
- diagnosis?
- treatment?
Diagnosis - Special (modified acid-fast) stains - Antigen detection (e.g., direct fluorescent antigen) - Polymerase chain reaction (PCR) - Histologic examination Treatment - Nitazoxanide is drug of choice
Cyclospora cayetanensis
- mode of transmission?
- typical hosts?
- Transmission is fecal, oral, or linked to fresh produce.
- Involves only humans as hosts
Cyclospora cayetanensis
- pathogenesis?
- Exhibits an influenza-like illness with nausea, vomiting, and explosive diarrhea.
- Can be associated with biliary disease.
Cyclospora cayetanensis
- prevention?
- Wear gloves while gardening in endemic areas.
- Wash produce.
- Reportable to Public Health Dept and CDC
Cyclospora cayetanensis
- diagnosis?
- difficult to see on wet mounts
- Special (acid-fast) stains—Oocysts appearing
pink to red
– Don’t stain well with trichrome - Ultraviolet (UV) epifluorescence
- Flow cytometry
Isospora (Cystoisospora) belli
- common name of disease?
- mode of transmission?
- Is implicated in traveler’s diarrhea
- passed in stool
Isospora (Cystoisospora) belli
- shape of oocysts?
- size of oocysts?
- Oocysts are long and oval
- 20-33µm long
Isospora (Cystoisospora) belli
- life cycle
- # of sporonts
- # of sporocysts
- # of sporozoites
- One immature sporont internally, may develop into two sporocysts, each with 4 sporozoites.
Isospora (Cystoisospora) belli
- Diagnosis?
- Examination of fresh material
- By wet mount.
- Auramine-rhodamine stain may be helpful
- Histologic examination
- No PCR
