2: COMMENSAL AMEBAE

Question 1

The three genera
of intestinal amebae can be differentiated
through the morphological features of their
________.

Answer 1

nuclei

Question 2

Trophozoites usually have only ______ nucleus.

Answer 2

one

Question 3

The genus _____________ has a vesicular nucleus with a relatively large, irregularly-shaped karyosome anchored to the nucleus by achromatic fibrils.

Answer 3

Endolimax

Question 4

The genus ____________ is characterized by a large, chromatin-rich karyosome surrounded by a layer of achromatic globules and anchored to the nuclear membrane by achromatic fibrils.

Answer 4

Iodamoeba

Question 5

All species have the following stages:

Answer 5

trophozoite, precyst, cyst, and metacystic
trophozoite; (with the exception of Entamoeba gingivalis)

Question 6

has no cyst stage, and does not inhabit the intestines

Answer 6

Entamoeba gingivalis

Question 7

Excystation occurs in the alkaline environment of the ________________________

Answer 7

lower small intestines

Question 8

__________________colonize the large intestines and live on the mucus coat covering the intestinal mucosa

Answer 8

Metacystic trophozoites

Question 9

____________________ is morphologically
similar to E. histolytica, but their DNA and
ribosomal RNA are different

Answer 9

Entamoeba dispar (isoenzyme pattern is different)

Question 10

It is a non-pathogenic species
that is morphologically indistinguishable
from E. histolytica and E. dispar, but differs
from them biochemically and genetically

Answer 10

Entamoeba moshkovskii i

Question 11

E. moshkovskii is also physiologically unique—it being _______________ , able to grow at room temperature (25-30°C optimum), able to survive at temperatures ranging from 0 to 41°C.

Answer 11

osmotolerant

Question 12

All human isolates have been found
to belong to one group___________.

Answer 12

“ribodeme 2

Question 13

The appearance of _____________ is relatively
similar to that of E. histolytica apart from its
smaller size.

Answer 13

E. hartmanni

Question 14

_____________ does not ingest red blood cells.

Answer 14

E. hartmanni

Question 15

______________ is cosmopolitan in
distribution, and is considerably more common than other human amebae.

Answer 15

Entamoeba coli

Question 16

E. coli can be differentiated from E. histolytica trophozoite by the following features:

Answer 16

1) a more vacuolated or granular endoplasm with bacteria and debris, but no red blood cells;
2) a narrower, less-differentiated ectoplasm;
3) broader and blunter pseudopodia used more for feeding than locomotion;
4) more sluggish, undirected movements; and
5) thicker, irregular peripheral
chromatin with a large, eccentric karyosome in the nucleus

Question 17

An E. coli cyst may be differentiated from
E. histolytica by:

Answer 17

1) its larger size (10 to 35 μm in diameter),
2) more nuclei (eight versus four in E. histolytica),
3) more granular cytoplasm, and
4) splinter-like chromatoidal bodies

Question 18

__________________ is a parasite found in
the intestines of pigs and monkeys.

Answer 18

Entamoeba polecki

Question 19

E. polecki can be distinguished from E.
histolytica in that the former’s cyst is:

Answer 19

• consistently uninucleated
• chromatoidal bars are frequently angular or pointed.

Question 20

__________________, which is found in apes
and monkeys, is morphologically identical to
E. polecki.

Answer 20

Entamoeba chattoni

Question 21

Identification of E. chattoni was done via ______________

Answer 21

isoenzyme analysis

Question 22

___________________ can be found in the mouth.

Answer 22

Entamoeba gingivalis

Question 23

It moves quickly, and has numerous
blunt pseudopodia.

Answer 23

Entamoeba gingivalis

Question 24

________________ lives on the surface of
gum and teeth, in gum pockets, and sometimes in the tonsillar crypts. They are abundant in cases of oral disease.

Answer 24

E. gingivalis

Question 25

This species has no cyst
stage. Transmission is most probably direct:
through kissing, droplet spray, or by sharing
utensils.

Answer 25

E. gingivalis

Question 26

__________________ occurs with the same
frequency as Entamoeba coli. Trophozoites
are small, with a diameter of 5 to 12 μm, and
exhibit sluggish movement. They have blunt,
hyaline pseudopodia, and the nucleus has a
large, irregular karyosome. Food vacuoles found in the cytoplasm may contain bacteria. Cysts measure about the same size as trophozoites, and are quadrinucleated when mature

Answer 26

Endolimax nana

Question 27

It is
identified by its characteristic large, vesicular
nucleus with a large, central karyosome,
surrounded by achromatic granules. There
are no peripheral chromatin granules on the
nuclear membrane.

Answer 27

Iodamoeba bütschlii

Question 28

Diagnosis is done through _________________.

Answer 28

stool examination

Question 29

Diagnosis for E. gingivalis

Answer 29

a swab between the gums and teeth
is examined for trophozoites

Question 30

Trophozoites are best demonstrated by __________________.

Answer 30

direct fecal smear

Question 31

In recovering cysts, the use of
_____________________________ is useful

Answer 31

concentration techniques like FECT and zinc
sulfate flotation