6. Flagellates Flashcards
a whiplike structures responsible for the
movement of the flagellates (trophozoite form).
flagella
Flagellates reside mainly in the:
✓Small intestines
✓Cecum
✓Colon
✓Duodenum (Giardia intestinalis)
are equipped
with thick, protective cell walls
and can survive in the outside
environment (similar to amebas).
flagellate cysts
finlike structure connected to the outer edge of some flagellates
Undulating membrane
rodlike support structure found in some flagellates
Axostyle
Flagellate identification:
✓Use of saline
✓Iodine wet preparations
✓Permanent stain
➢Common disease:
* Giardiasis, traveler’s diarrhea
➢Initially known as:
* Cercomonas intestinalis
➢Stiles coined the term:
* Giardia lamblia
➢Some also consider the term:
* Giardia duodenale (as a synonym)
Giardia intestinalis
Giardia intestinalis
Trophozoite
➢Shape
* Pear-shaped, teardrop
➢Motility
* Falling leaf
➢Appearance
* Bilaterally symmetrical
Giardia intestinalis
Cysts
➢Shape
* Ovoid
➢Nuclei
* Immature cyst, two mature cysts, four central
karyosomes, NO peripheral chromatin
➢Cytoplasm
* Retracted from cell wall
Giardia intestinalis
Laboratory Diagnosis
➢Enterotest - duodenal contents using string test.
➢Fecal antigen detection by Enzyme Immunoassays (EIA) and Enzyme-linked Immunosorbent Assay (ELISA)
➢Direct Fluorescence detection (Giardia and Cryptosporidium)
➢Giardia western immunoblotting (blot)
➢Real-time polymerase chain reaction (RT-PCR) – molecular method sensitive enough for environmental
monitoring.
Considered to be one of the most common intestinal
parasite, especially among children.
Giardia intestinalis
Found worldwide in lakes, streams, and other water
sources.
Giardia intestinalis
are resistant to the routine
chlorination procedures.
Giardia intestinalis cyst
_____ as well as _____ of this water is crucial to obtain adequate drinking water.
- Filtration
- Chemical treatment
now considered to be
the only known pathogenic intestinal flagellate
Giardia intestinalis
also known Traveler’s disease
Giardia intestinalis
Typical incubation period of Giaria intestinalis
10-36 days
Giardia is a self-limiting condition that typically is
over in after onset.
10 to 14 days
Patients with _____ or an
______ appear to be
particularly susceptible to reoccurring infection.
- intestinal diverticuli
- immunoglobulin A (IgA) deficiency
Primary choice of treatment for G. intestinalis infection
(according to CDC):
✓Metronidazole, Tinidazole, and Nitazoxanide
G. intestinalis is discovered in ____ by ____ when he examined a sample of his own stool.
- 1681
- Anton van
Leeuwenhoek
First known rough description of Giardia was written by the
Secretary of the Royal Society of London
Robert Hooke
Giardia trophozoites have often been
referred to as resembling an
old man’s face with whiskers
are both known to be
carriers of double-stranded RNA
viruses.
G. intestinalis and Trichomonas
vaginalis
Chilomastix mesnili
Trophozoite
➢Shape – Pear-shaped
➢Motility – Stiff, rotary, directional
Chilomastix mesnili cysts
➢Shape – Lemon-shaped, with a clear hyaline knob extending from the anterior end
➢Nuclei – One, with large central karyosome, No peripheral chromatin
(Chilomastix mesnili)
often demonstrate the
organism’s features most clearly.
Iodine wet preparations
➢Once inside the human body, it is known to reside in the mucosal crypts of the large intestine.
Dientamoeba fragilis
One unproven theory suggests that is transmitted via the eggs of helminth parasites such as
Enterobius vermicularis and Ascaris lumbricoides.
D. fragilis
Dientamoeba fragilis Treatment
✓Iodoquinol – treatment of choice
✓Tetracycline – acceptable alternative treatment
Feature diagnostic for the identification of D. fragilis.
Hakansson phenomenon
numerous granules are present in this stage
and exhibit Brownian motion
Hakansson phenomenon
the erratic random movement of microscopic particles in a fluid
Brownian motion
Enteromonas hominis Trophozoite
➢Shape – Oval; sometimes half circle
➢Motility – Jerky
Enteromonas hominis Cyst
➢Nuclei – One to four, Binucleated and
quadrinucleated nuclei located at opposite ends, Central karyosome. No
peripheral chromatin.
Enteromonas hominis treatment
not indicated
(nonpathogen)
Retortamonas intestinalis Trophozoite
➢Shape – Ovoid
➢Motility – Jerky
➢Nuclei – One, with small central karyosome. Ring of chromatin
Retortamonas intestinalis Cyst
➢Shape – Lemon-shaped, pear-shaped
➢Nuclei – One, located in anterior-central
region with central karyosome. May be surrounded by a delicate ring of chromatin
granules.
Two fused fibrils resembling a bird’s beak in the anterior nuclear region
Retortamonas intestinalis
Trichomonas hominis Trophozoite
➢Shape – Pear-shaped
➢Motility – Nervous, jerky
➢Nuclei – One, with a small central karyosome. No
peripheral chromatin.
Common Disease:
Persistent urethritis,
Persistent vaginitis,
Infant Trichomonas
vaginalis infection
Trichomonas vaginalis
Trichomonas vaginalis
Trophozoite
➢Shape – Ovoid, round or pear-shaped
➢Motility – Rapid, Jerky
➢Nuclei – One, ovoid, nondescript
➢Flagella – All originating anteriorly: Three to five
extending anteriorly, One extending posteriorly.
➢Trophozoites reside on the ____ of the vagina in infected women.
➢Trophozoites multiply by _____ and feed on local bacteria and leukocytes.
➢Trophozoites thrive in a _____ or _____ environment.
➢Most common infection site of T. vaginalis in male: _____
- mucosal surface
- longitudinal binary fission
- slightly alkaline or slightly acidic pH
- Gland region and the epithelium of the urethra
Trophozoites are by nature hardy and resistant to changes in their environment.
Trichomonas vaginalis
Persistent vaginitis incubation period
4 to 28 days
Trichomonas vaginalis Treatment of choice
Metronidazole
Trichomonas tenax Trophozoite
➢Shape – Oval, pear-shaped
➢Nuclei – One, ovoid nucleus; consist of
vesicular region filled with chromatin
granules.
Trichomonas tenax specimen of choice
Mouth scrapings
