PARASITOLOGY 1st Topic Flashcards
can become parasitic or
survive outside the host
Free living Amoeba
the mode of replication by N. fowleri trophozoite
Promitosis
Naegleria spp. are ________________________
which thrive best in hot springs and other warm
aquatic environments
thermophilic organisms
N. fowleri trophozoites are found in ___________________ and ______ , while flagellated forms are
occasionally found in _____. Cysts are not seen
in _______________
cerebrospinal fluid
(CSF), tissue
CSF
brain tissue
N. fowleri are Motile, by means of __________________
blunt, rounded
pseudopodia
Infective stage of N. fowleri
Trophozoite stage
Diagnostic Stage of N. fowleri
Trophozoite in CSF and Tissue
N. fowleri most common form found in the environment is the
______________________
trophozoite stage.
where does N. fowleri enter the brain once attached in the ________________ and migrate to the brain through the ________________
nasal mucosa, Olfactory Nerves
N. fowleri is the causative agent of a rare but rapidly destructive and fatal
meningoencephalitis termed ________________________________
primary amebic
meningoencephalitis (PAM)
Naegleria trophozoites can be identified by
the presence of _____________________ and
_____________________
blunt, lobose pseudopodia , directional motility
_______________ in combination with
__________________ is synergistic, and has been
successfully used to treat PAM
Amphotericin B, clotrimazole
_________________________ produces deleterious changes in the nucleus and mitochondria of the ameba, decreases
the number of food vacuoles, and increases
the formation of autophagic vacuoles
Amphotericin B
Ameba exposed to ___________________ exhibit decreased
pseudopod formation and form blebs on
the plasma membrane.
amphotericin B
N. fowleri’s specialized feeding structures that help in phagocytosis and ingestion of host cells.
Amoebastome (“food cups”)
Allow the survival and growth of N. fowleri in warm temperatures
Heat Shock Proteins
Infection of N. fowleri can be prevented through _________________ of water at _____, or higher
especially in swimming pools
Chlorination, 1ppm
Staining N. fowleri with Wright or Giemsa stains or Fluorescent stains – Appeared as
____________ nuclei with ___________ cytoplasm
small pink, sky blue
is a ubiquitous, free-living
ameba that is the etiologic agent of AK and GAE
Acanthamoeba spp.
diseases caused by Acanthamoeba spp.
Acanthamoeba keratitis and Granulomatous amebic encephalitis
Acanthamoeba is
characterized by an ________________ stage
with characteristic prominent “thorn-like”
appendages _______________________
active trophozoite, acanthopodia
Motile trophozoites of Acanthamoeba spp. feed on __________________________
gram negative bacteria, blue-green algae, or yeasts
Acanthamoeba spp. trophozoite reproduce by _________
Mitosis
infective stage of the Acanthamoeba spp.
Trophozoite stage
Examples of naturally-occurring bacterial endosymbionts in Acanthamoeba
spp.
Legionella spp., mycobacteria,
and gram-negative bacilli such as E. coli
Incubation period of PAM
2-15 days (Average 5 days)
associated with the
use of improperly disinfected soft contact
lenses, particularly those which are rinsed with
tap water or contaminated lens solution.
Acanthamoeba keratitis
GAE usually occurs
in _______________________ hosts
immunocompromised
most virulent Acanthamoeba spp; binds more firmly to host cell membrane surfaces
T4 genotype
Acanthamoeba spp. that are Usually more associated with ocular
infection and keratitis
A. castellani & A. polyphaga
Acanthamoeba spp. that are Usually more associated with Acanthamoeba
granulomatous encephalitis
A. culbertsoni
Acanthamoeba spp. incubation period from initial inoculation
is about ______
10 days
Virulence factors of Acanthamoeba spp.
Mannose-binding protein
Contact-dependent metalloproteinase and several contact-independent serine
proteinases
mediates adhesion by recognizing and binding to mannose
residues on the surface of host cells, particularly on corneal epithelial cells
Mannose-binding protein
The likely method taken by Acanthamoeba spp. to enter the CNS
Hematogenous
Acanthamoeba spp. neural tissue postmortem reveals cerebral hemispheres that are
___________________, with areas of ____________________
edematous and soft
hemorrhage and focal abscesses
Acanthamoeba spp. most affected areas of the brain are the ___________________________________
posterior fossa structures,
thalamus, and the brainstem.
Acanthamoeba keratitis is diagnosed by
______________________________ for
recoverable ameba with characteristic staining
patterns on histologic analysis.
epithelial biopsy or corneal scrapings
destruction of brain tissue and the
associated meningeal irritation.
Granulomatous Amebic Encephalitis
Medical treatment of AK (acanthamoeba keratitis)
clotrimazole combined with pentamidine, isethionate, and neosporin
Clinically apparent neurologic disease in
GAE usually heralds a fatal outcome within
_____________________
3 to 40 days
In GAE, Parasite adhesion and damage to
endothelial cell is made possible by secreting
the _________________________
mannose-binding protein
if the acanthamoeba infection is confined to more superficial areas.
_____________________is the procedure of
choice.
Deep lamellar keratectomy
Clinically apparent neurologic disease in
GAE usually heralds a fatal outcome within
_________________________.
3 to 40 days
All stages of development of Cryptosporidium hominis are completed in
the ______________________ of the host
gastrointestinal tract
Oocysts produced by C. hominis are found in the ______ of humans and other animals
feces
the oocyst of C. hominis contains ________________, which are present at the time of passage into the feces
four sporozoites
Infective stage of C. hominis
Thick walled oocyte
The oocyst of C. hominis is infectious and when ingested, the
sporozoites attach to the surface of ___________________________________-
epithelial
cells of the gastrointestinal tract
The sporozoites of C. hominis develop into ___________________ and become _____________________ but _______________c, and attach to the brush borders.
small trophozoites, intracellular, extracytoplasmi
The trophozoites of C. hominis divide
by ________ producing __________ that infect
other cells
schizogony, merozoites
The ________________ of C. hominis infect other enterocytes thus resulting
in autoinfection, which is possibly responsible
for the chronicity of the infection among the
immunocompromised
thin-walled oocysts
the ____________________ of C. hominis are passed out with the feces that may contaminate food and water, which are ingested by the same or another host
thick-walled oocysts
Cryptosporidiosis hominis may present as a self-limiting diarrhea lasting for ___________________
2 to 3 weeks
There are several methods of stool
examination that will reveal C. hominis oocyst.
_____________________ and the ____________________
are commonly used
Sheather’s sugar flotation, Formalin ether/ethyl acetate concentration technique
_______________ is routinely used with the C. hominis oocysts appearing as red-pink doughnut-shaped circular organisms in a blue background
Kinyoun’s modified acidfast stain
reported effective treatment for Cryptosporidiosis hominis
Nitazoxanide
Swimming pool disinfection
with 3 to 5 mg/L of chlorine _____________
the C. hominis oocysts
does not kill
most common mode of
transmission of C. hominis is from ________________________
one person to another
Cyclospora cayetanensis was thought to be a
member of __________________because it showed photosynthesizing organelles and autofluorescing particles characteristic of the
blue green algae.
cyanobacteria
The first stage of the life cycle of C. cayetenensis
Ingestion of sporulated oocysts, containing 2 sporocysts and 2 sporozoites
The released sporozoites C. cayetenensis invade the _____________________, although the site of predilection was found to be the ___________
epithelial cells of the small intestines, jejunum
Multiple fissions of the C. cayetenensis sporozoites
take place inside the cells to produce meronts,
which contain _______________ merozoites during the first generation, and only ___________ merozoites in
the second generation
8 to 12, 4
The oocysts C. cayetenensis undergo complete sporulation within _______________ in a warm environment.
7 to 12 days
Infective stage of C. cayetenensis
Sporulated oocysts
Initial symptoms of cyclosporiasis include ____________________ and ________________, which may occur ______________________
after exposure.
malaise and low
grade fever, 12 to 24 hours
recommended method of sample and procedure for the diagnosis of cyclosporiasis
Direct microscopic examination of fecal
smears under high magnification (400x)
Drug recommended for cyclosporiasis
trimethoprim-sulfamethoxazole
160/800 mg twice daily for 7 days
Diagnostic stage of C. cayentenensis
Unsporulated oocysts
Diagnostic stage of C. hominis
thick walled oocysts (sporulated)
causative agent of a medical condition affecting the small bowel called cystoisosporiasis
Cystoisospora belli
Cystoisospora belli sporulated oocyst contains ___________________ each containing _______________________
two sporocysts, four sporozoites
(infective stage)
Sporulation of Cystoisospora belli usually occurs within _______________________ after passage with the stool.
48 hours
oocysts C. belli can be seen in a
fecal smear stained by a _______________________________, where they stain granular red color
against a green background
modified Ziehl-Neelsen method
Poeple infected with cystoisospora Mucosal bowel biopsy may reveal _________________ and _________________
flattened mucosa and damaged villi
treatment for cystoisosporadiasis
trimethoprim-sulfamethoxazole 160/800 mg four times per day for 10 days, then two times
per day for 3 weeks
the only known hosts of C. belli`
humans
Toxoplasma gondii infective stage
tachyzoite,
the bradyzoite, and the oocyst
Toxoplasma gondii definitive host
members of the cat family
extraintestinal asexual stage of Toxoplasma gondii
Tachyzoites and bradyzoites
Toxoplasma gondii oocysts complete
sporulation within __________________ days.
three to four
Inside the mature oocyst of Toxoplasma gondii , ____ sporocysts are formed, each having _____ sporozoites
two, four
fast multiplying stage of T. gondii
Tachyzoites
slow multiplying stage of T. gondii
Bradyzoites
Asexual multiplication of T. gondii
endodyogeny
Organelles of T. gondii, such as ______________________, which are associated with
cell penetration, are found in a short conoid
on the anterior end.
rhoptries and micronemes
Among the immunocompromised
patients, the most common manifestation of toxoplasmosis is
____________________
encephalitis
test used for the identification of T. gondii
Sabin-Feldman
methylene blue dye test
Treatment for T gondii
pyrimethamine and sulfadiazine used in combination for 1 month
parasite that lacks a cell wall
Blastocystis hominis
most predominant
forms in fecal specimens of B. hominis
Vacuolated form
The ________________ are considered
to be the main type of Blastocystis that cause
diarrhea.
vacuolar forms
this stage allows the parasite B. hominis to ingest bacteria
in order to enhance encystment
amebic form
stain used to differentiate the different stages of B. hominis
Hematoxylin and Trichrome
Drug of choice for treatment of B. hominis
Metronidazole
