Acanthamoeba spp, Naegleria

Question 1

Acanthamoeba is a ubiquitous, free-living
ameba that is the etiologic agent of
AK and GAE

what is AK and GAE

Answer 1

Acanthamoeba keratitis (AK)

and granulomatous amebic encephalitis (GAE)

Question 2

is characterized by an active trophozoite stage
with characteristic prominent “thorn-like”
appendages (acanthopodia); and a highly
resilient cyst stage into which it transforms when environmental conditions are not favorable

Answer 2

Acanthamoeba

active trophozoite, resilient cysts

Question 3

It is an aquatic organism that is found in a
myriad of natural and artificial environments,
and can survive even in contact lens cleaning
solutions.

Answer 3

Acanthamoeba

Question 4

foods of acanthamoeba trophozoites

Answer 4

gram negative bacteria
blue-green algae
yeasts
corneal epithelial cells
neurologic tissue

Question 5

acanthamoeba trophozoites

nucleus
nucleolus
endosome
cytoplasm
locomotion

Answer 5

nucleus: centrally located
nucleolus: densely stained
endosome: large endosome
cytoplasm: finely granulated cytoplasm
locomotion: small, spiny filaments acanthopods

Question 6

2 stages of life of acanthamoeba

Answer 6

troph and cysts

Question 7

infective stage of acanthamoeba

Answer 7

trophozoites

Question 8

MOT of acanthamoeba

Answer 8

Entry can occur through the
eye, the nasal passages to the lower respiratory tract, or ulcerated or broken skin

Question 9

was first described as an
opportunistic ocular surface pathogen causing
keratitis in 1974

Answer 9

Acanthamoeba

Question 10

associated with the use of improperly disinfected soft contact lenses, particularly those which are rinsed with tap water or contaminated lens solution

Answer 10

Acanthamoeba keratitis

Question 11

Symptoms of AK include

Answer 11

severe ocular pain and blurring of vision

Question 12

Primary amebic infection or secondary bacterial infection may lead to __ formation.

Answer 12

hypopyon

Question 13

Acanthamoeba was documented as the
causative agent of human GAE by WHOM in
1972

Answer 13

STAMM

Question 14

Amebae were demonstrated in brain
sections of a GAE patient using

Answer 14

indirect fluorescence microscopy

Question 15

Signs and symptoms of GAE are generally
related to

Answer 15

destruction of brain tissue and the
associated meningeal irritation

Question 16

Gross examination of neural tissue postmortem reveals cerebral hemispheres that are

Answer 16

edematous and soft, with areas of hemorrhage and focal abscesses

Question 17

s. The most affected areas
of the brain by acanthamoeba are the

Answer 17

posterior fossa structures,
thalamus,
and the brainstem

Question 18

Acanthamoeba keratitis is diagnosed by

Answer 18

epithelial biopsy

or corneal scrapings for
recoverable ameba with characteristic staining
patterns on histologic analysis

Question 19

Diagnosis of GAE is usually made ____ in most cases.

Answer 19

postmortem

Question 20

3 forms of naegleria spp

Answer 20

2 vegetative
- amoeba - trophozoite
- swimming form - flaggelate

and 1 dormant cysts

Question 21

There are two forms of trophozoites of
Naegleria fowleri:

Answer 21

ameboid and ameboflagellate,

Question 22

There are two forms of trophozoites of
Naegleria fowleri: ameboid and ameboflagellate,
only the ___ of which is found in humans

Answer 22

ameboid

Question 23

are thermophilic organisms
which thrive best in hot springs and other warm
aquatic environments

Answer 23

Naegleria

Question 24

Only Naegleria _____
has been reported to consistently cause disease
in humans

Answer 24

fowleri

Question 26

Naegleria fowleri has three stages,

Answer 26

cysts, trophozoites, and flagellated forms,

Question 28

The trophozoites replicate by ___ (nuclear membrane remains intact) and can turn into temporary non-feeding flagellated forms,

Answer 28

promitosis

Question 29

how the trophozoites of naegleria fowleri infect humans

Answer 29

Trophozoites infect humans or animals by penetrating the nasal mucosa and migrating to the brain via the olfactory nerves

Question 30

where can we find Trophozoites of N. fowleri

Answer 30

CSF and tissue

Question 31

where can we find flagellated forms of N. fowleri

Answer 31

occasionally in CSF

Question 32

the form of N. fowleri that is not found in brain tissue

Answer 32

cysts

Question 33

N. fowleri is the causative agent of a rare but rapidly destructive and fatal meningoencephalitis termed

Answer 33

primary amebic meningoencephalitis (PAM)

Question 34

In contrast to GAE which is predominantly an opportunistic infection, PAM usually occurs in previously healthy adults with a history of ___

Answer 34

swimming

Question 35

Therefore, in contrast to Acanthamoeba which is largely an opportunistic organism, N. fowleri is considered a true pathogen. true or false

Answer 35

true

Question 36

N. fowleri is able to survive in elevated temperatures and reproduces rapidly in temperatures above ___°C.

Answer 36

30

Question 37

The route of entry is through invasion of N. fowleri through the _____ after accidental inhalation of water containing the organisms.

Answer 37

olfactory bulb

Question 38

In humans, PAM presents as

Answer 38

fever, nausea, vomiting, headache, nuchal rigidity, and mental status changes, with rapid progression to coma and death

Question 39

Post-mortem examination of infected brain by N.fowleri shows

Answer 39

hemorrhagic necrosis, particularly of the olfactory bulbs, congestion and edema of neural tissue

Question 40

Naegleria trophozoites can be identified by the presence of ___, ____ pseudopodia and ____ motility

Answer 40

blunt, lobose, directional

Question 41

____ in combination with ____ is synergistic, and has been successfully used to treat PAM

Answer 41

Amphotericin B; clotrimazole

Question 42

Naegleria fowleri is easily killed by ___ of water at 1 ppm or higher

Answer 42

chlorination