Chapter 47 - Intestinal Protozoa Flashcards
(53 cards)
1
Q
Intestinal Protozoa:
- Uni/multicellular?
- Pro/eukaryotic?
- How do they multiply?
A
- Are unicellular eukaryotic organisms.
- Multiply by binary fission.
2
Q
Amoebae (Sarcodina)
- What do they use for movement?
- (Non)pathogenic?
A
- Contain pseudopodia (cytoplasmic protrusions).
- Are free living, pathogenic or nonpathogenic
3
Q
Entamoeba histolytica
- What diseases is this responsible for?
- How is it transmitted?
- Describe the movement.
A
- Agent of amebic colitis and amebic liver abscess
- Fecal oral route
- Rapid and unidirectional movement
4
Q
Entamoeba histolytica
- Describe the chromatin arrangement.
- Describe the karyosome.
- Describe the cytoplasm.
A
- Evenly arranged chromatin on nuclear membrane.
- chromatiodal body/bar in cysts
- Small compact karyosome
- multiple in cysts
- Cytoplasm finely granular
5
Q
Entamoeba histolytica
- What does it like to eat?
A
- Red blood cells (RBCs) in cytoplasm
- - *no longer a diagnostic feature of E. histolytica
6
Q
Entamoeba dispar
- How many of these samples contain ingested RBCs?
A
- 16% of E. dispar clinical samples contain ingested red blood cells
7
Q
Entamoeba histolytica
- What stages must be reported?
- How big are members of each stage?
A
- Must report cysts and/ or trophs
- Size
- Trophs 12-60µm (usual 15-20µm)
- Cysts 10-20µm
8
Q
Entamoeba histolytica
- What ailments is it responsible for?
- What does it do to the cells/tissues?
A
- Amebic colitis
- Liver involvement
- Amebic lesions, cell lysis and tissue necrosis.
9
Q
Entamoeba histolytica
- What is the process by which trophs cause pathogenesis?
A
- Trophs interact through a series of steps:
- Adhesion to the target cell
- Phagocytosis
- Cytopathic effects
10
Q
Entamoeba histolytica
- Where does cyst formation occur?
A
- Cysts formation only occurs in the intestinal tract, infective stage and mode of transmission
11
Q
Entamoeba histolytica
- What type of immune response does it induce?
A
- Induces both humoral and cell mediated immune responses
12
Q
Entamoeba histolytica
- What two classes of drugs are used for treatment?
A
- Luminal amebicides
- Tissue amebicides
13
Q
Entamoeba histolytica
- What are four different methods for detection?
A
- Antigen detection
- Histology
- Nucleic acid–based tests
- Real-time PCR
- Multiplex assays
- Serologic detection
14
Q
Entamoeba dispar
- what parasite is this morphologically identical to?
- (non)pathogenic?
A
- 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
15
Q
What are four main features that distinguish E. dispar from Entamoeba coli?
- E. coli (non)pathogenic?
A
- Entamoeba coli
- Cysts ingested, produce trophs in intestinal tract to excreted infective cysts.
- Trophs larger.
- Chromatoidal bars-splintered
- Mature cyst 8 nuclei
- nonpathogenic
16
Q
Endolimax nana
- (non)pathogenic?
- Cyst shape?
A
- nonpathogenic
- cyst is spherical/ovoid in shape
17
Q
Endolimax nana mature cyst
- size?
- how many nuclei?
- describe the cyst wall.
- Chromatoidal bodies?
A
- Diameter: 5-15um
- 4 nuclei when mature
- refractile cyst wall
- c. bodies not usually found
18
Q
Endolimax nana
- size?
- describe the cytoplasm.
- how many nuclei?
- describe the nuclei.
- chromatin?
- describe the pseudopodia.
- motility?
A
- 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
19
Q
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?
A
- 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
20
Q
Blastocystis hominis
- what are the four major forms?
A
- Cyst (thick- and thin-walled)
- Central vacuole (central body)
- Amoeboid (rare)
- Granular (in culture)
21
Q
Blastocystis hominis
- What are the symptoms?
A
- Causes diarrhea, cramps, nausea, fever, and vomiting
22
Q
Blastocystis hominis
- what are the three most common ways to make a diagnosis?
A
- Routine stool examination. Quantitate
- Antigen detection using enzyme-linked immunosorbent assays (ELISAs)
- Antibody detection using ELISA and fluorescent antibody tests
23
Q
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?
A
- 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
24
Q
Giardia lamblia (duodenenalis)
- mode of transmission?
- symptoms?
A
- Is acquired from contaminated food or drink.
- Giardiasis causes diarrhea with no blood, mucus, or exudate.
25
```
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
26
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
27
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
28
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)
```
29
```
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
30
```
Giardia lamblia (duodenenalis)
- what is the treatment?
```
- Self-limiting
- Metronidazole
- nitrazoxanide
- tinidazole
31
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
32
Dientamoeba fragilis
- Collection methods?
- Viability/stability?
Collection
- 3 samples
- 24 to 48 hours of viability of trophs
- Have been recovered in formed stool.
33
Dientamoeba fragilis
| - Symptoms?
- Diarrhea
- Abdominal pain
- Nausea
- Poor weight gain
- Eosinophilia
34
```
Flagellates:
Chilomastix mesnili
- pathogenic?
- shape of troph?
- # of nuclei?
- define cytostome.
```
- Nonpathogenic
- Pear shaped trophozoite
- Single nucleus
- Distinct oral groove(cytostome)
35
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)
36
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
```
37
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
38
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
```
39
Balantidium coli
- cytoplasm?
- diagnosis?
- treatment?
- Cytoplasm with many vacuoles
- Best by direct smear
- Tetracycline
40
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
41
Cryptosporidium spp. (parvum)
- method of transmission?
- where does it infect?
- Are acquired from contaminated water or infected persons.
| - Infect epithelial cells of gastrointestinal tract
42
Cryptosporidium spp. (parvum)
| - life cycle?
- Ingestion of oocysts
- Trophozoite development
- Merogony (asexual amplification)
- Gametogony (sexual differentiation)
- Formation of new oocytes (sporogony)
43
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
44
Cryptosporidium spp
- Extracelular stage?
- Typical age of patient?
- The only extracellular stage is the oocyst.
| - Infection of children <5yo.
45
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
```
46
Cyclospora cayetanensis
- mode of transmission?
- typical hosts?
- Transmission is fecal, oral, or linked to fresh produce.
| - Involves only humans as hosts
47
Cyclospora cayetanensis
| - pathogenesis?
- Exhibits an influenza-like illness with nausea, vomiting, and explosive diarrhea.
- Can be associated with biliary disease.
48
Cyclospora cayetanensis
| - prevention?
- Wear gloves while gardening in endemic areas.
- Wash produce.
- Reportable to Public Health Dept and CDC
49
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
50
Isospora (Cystoisospora) belli
- common name of disease?
- mode of transmission?
- Is implicated in traveler’s diarrhea
| - passed in stool
51
Isospora (Cystoisospora) belli
- shape of oocysts?
- size of oocysts?
- Oocysts are long and oval
| - 20-33µm long
52
Isospora (Cystoisospora) belli
- life cycle
- - # of sporonts
- - # of sporocysts
- - # of sporozoites
- One immature sporont internally, may develop into two sporocysts, each with 4 sporozoites.
53
Isospora (Cystoisospora) belli
| - Diagnosis?
- Examination of fresh material
- - By wet mount.
- Auramine-rhodamine stain may be helpful
- Histologic examination
- No PCR
