Free-living Amoeba Flashcards
These parasites, classified under free-living amoeba, can cause disease
among humans thus, more appropriately called opportunists.
Naegleria fowleri
Acanthamoeba culbertsoni
Acanthamoeba castellani
Acanthamoeba astronyxis
Acanthamoeba polyphaga
Opportunist amoeba may be classified under 2 genera,
(1) Naegleria
(2) Acanthamoeba
Species of genus Naegleria are classified as
ameboflagellate
True or False:
Acanthamoeba species do not have flagellate forms.
In general, Naegleria fowleri causes primary
amoebic meningoencephalitis
(PAM)
Also known as the brain-eating amoeba. It the causative parasite of a rare and fatal infection of the brain called primary amoebic meningoencephalitis .
Naegleria fowleri
People usually get infected when contaminated water enters the body
through the
nose
This stage has amoeboid and flagellate forms, colonizes water and moist soil, and is the only stage demonstrated in the tissues of man.
trophozoite
The second stage is the ______________ which
is the non-motile resistant form.
cyst
has an elongated anterior and distinctly tapered posterior end forming a single clear pseudopod at the forward end and a knoblike structure called uroid process.
Amoeboid form
Trophozoite
It measures 7 X 20 μm
when active and 10-5 μm (diameter) when rounded.
Amoeboid form
Trophozoite
pear-shaped with two flagella at the broader end. It may move forward rapidly or spin.
Flagellate form
stage that forms in agar culture media and the one found in nature. It is spherical with a single nucleus, measuring 7-10 μm in diameter, with a smooth, heavy, and thick cyst wall.
cyst
(PAM) is acquired through instillation of trophozoite into
The nose when the person swims
in infected bodies of water.
The trophozoites can go into the brain via
Olfactory nerve epithelium
Meningeal irritation leads to
Neck stiffness or generalized
seizure or convulsion.
The recommended treatment for Naegleria infection is
Combination of Amphotericin B and Miltefosine.
an antifungal drug that is usually given intravenously or into the space around the spinal cord.
Amphotericin B
An investigational drug used in breast cancer and leishmaniasis. It shows effective in killing Naegleria amoeba in vitro and animal studies.
Miltefosine
The organism may be recovered from the CSF obtained through _____ puncture
Lumbar puncture wound
staining methods preffered in Naegleria infection
Iron-Hematoxylin or Wright’s staining methods
-Immuno fluorescence and/or immunoperoxidase methods may also be used
can be found in the soil, fresh, brackish and sea water, and dust in air. They are also obtained from Jacuzzis, air-conditioning and
ventilating units, dialysis machines, and even contact lens.
Acanthamoeba species
Is the active stage in Acanthamoeba
The trophozoite
Species of Acanthamoeba produce
granulomatous amoebic
meningoencephalitis (GAE)
The resistant stage in Acanthamoeba
the cyst
Known portals of entry with Acanthamoeba
ulcerated or broken skin, the eyes, genitourinary tract, and probably the lungs.
were found in cases of eye infections only
A. polyphaga and A. hatchetti
Most cases of GAE with eye infection were due to
A. castellani.
Treatment for Acanthanmoeba
Anti-infective drugs are used in the early stages, and surgical procedure are done for
later stages to remove infected tissues.
Acanthamoeba eye infections are effectively
treated with
topical miconazole, metronidazole, and neomycin. Oral ketoconazole can also be given.
Laboratory diagnosis is through identification of trophozoites in the CSF
through
hanging-drop preparation or recovery of cysts and trophozoites in brain
tissues.
Differentiation in Acanthamoeba is easier with the use of
immunoperoxidase and
immunofluorescent staining procedures.
