Question 1

The presence of which of the following cells is diagnostic for the intestinal protozoan, Entamoeba histolytica, which measures 15 to 20 microns?

Accepted Answer

A)   Yeast
B)   White blood cells (WBCs) 
C)   Red blood cells (RBCs) 
D)   Bacteria C

Question 2

This flagellate is pear-shaped with "falling leaf" motility.It contains variant-specific surface proteins (VSPs)on its surface, which provide a mechanism for the organism to survive in the small intestine as a result of its ability to resist intestinal proteases.The organism is:

Accepted Answer

A)   Giardia lamblia.
B)   Chilomastix mesnili.
C)   Dientamoeba fragilis.
D)   Enteromonas hominis. A

Question 3

Which of the following flagellates has a single nucleus in the cyst and the typical curved, cytostomal fibril, which is called a shepherd's crook?

Accepted Answer

A)   Giardia lamblia
B)   Chilomastix mesnili
C)   Dientamoeba fragilis
D)   Enteromonas hominis B

Question 4

When cooking meat, an internal temperature of ____° C must be reached to kill organisms such as Toxoplasma and Sarcocystis.

Accepted Answer

A)   38
B)   48
C)   58
D)   68

Question 5

The drug of choice for the parasite Blastocystis hominis, which is believed to produce proteases and is considered a virulence factor responsible for its pathogenesis, is:

Accepted Answer

A)   metronidazole.
B)   albendazole.
C)   tetracycline.
D)   nitazoxanide.

Question 6

A patient has amebic colitis.A microscopic examination reveals the following: • 18 microns in diameter
• Fine granules
• Centrally located karyosome
• Cytoplasm with a "ground glass" appearance
• RBC inclusions
This protozoan can be identified as:

Accepted Answer

A)   Entamoeba dispar.
B)   E. histolytica.
C)   E. hartmanni.
D)   E. coli.

Question 7

An intestinal protozoan appeared 8 microns in diameter with a small, compact, centrally located karyosome.Four nuclei were observed in the mature cyst.The organism can be identified as:

Accepted Answer

A)   E. histolytica.
B)   E. dispar.
C)   E. hartmanni.
D)   E. coli.

Question 8

Asexual amplification, called merogony, is associated with the life cycle of which organism?

Accepted Answer

A)   Cyclospora
B)   Cryptosporidium
C)   Toxoplasma
D)   Sarcocystis

Question 9

The Isospora belli organism, which contains two sporocysts with four sporozoites each, is recovered from fecal specimens and has also been implicated in traveler's diarrhea.The drug of choice to treat infection caused by I.belli is:

Accepted Answer

A)   trimethoprim-sulfamethoxazole combination.
B)   tetracycline.
C)   albendazole.
D)   flagyl.

Question 10

The peripheral chromatin, which contains fine granules that are uniform in size and are evenly distributed, can be found in which one of the following protozoa?

Accepted Answer

A)   Endolimax nana
B)   Iodamoeba butschlii
C)   Entamoeba coli
D)   Entamoeba histolytica

Question 11

The organism Sarcocystis has an obligatory two-host life cycle-an intermediate host and definitive host.The sporocysts found in a stool specimen, which measure 9 to 16 microns, are broadly oval with slightly ___________ ends.

Accepted Answer

A)   blunt
B)   tapered
C)   rounded
D)   flattened

Question 12

Outbreaks of infection with the organism Cyclospora are linked to contaminated raspberries, lettuce, and snow peas.The stain of choice to identify the oocysts in stool samples is:

Accepted Answer

A)   trichrome.
B)   Wright.
C)   periodic acid-Schiff.
D)   modified acid-fast.

Question 13

Which of the following nonpathogenic protozoa has a very large glycogen vacuole in its cyst form and measures approximately 5 to 20 microns in diameter?

Accepted Answer

A)   Entamoeba coli
B)   Iodamoeba butschlii
C)   Entamoeba dispar
D)   Endolimax nana

Question 14

A tissue sample is sent to the laboratory and microscopically examined for the presence of amebae.To differentiate between the host cells and the organism, _______ stain is used to allow the organisms to appear bright pink with a green-blue background.

Accepted Answer

A)   trichrome
B)   Giemsa
C)   Wright
D)   periodic acid-Schiff (PAS)

Question 15

Which of the following intestinal protozoa has no cyst stage, ranges from 9 to 12 microns in diameter, and has two nuclei in 60% of clinical specimens?

Accepted Answer

A)   Giardia lamblia
B)   Chilomastix mesnili
C)   Dientamoeba fragilis
D)   Enteromonas hominis

Question 16

Highly active antiretroviral therapy (HAART)is the most effective prophylaxis and treatment in patients with acquired immunodeficiency syndrome (AIDS)with which type of infection?

Accepted Answer

A)   Cyclospora
B)   Sarcocystis
C)   Cryptosporidium
D)   Toxoplasma

Question 17

The polar tubule, which is responsible for the entrance of infective sporoplasm into the host cell, is found in which of the following genera?

Accepted Answer

A)   Blastocystis
B)   Sarcocystis
C)   Enterocytozoon
D)   Entamoeba

Question 18

A patient is diagnosed with a severe intestinal disease caused by Entamoeba histolytica.Which of the following treatments should be administered?

Accepted Answer

A)   Diloxanide furoate
B)   Metronidazole
C)   Metronidazole plus iodoquinol
D)   Iodoquinol and diloxanide furoate

Question 19

Entamoeba coli, a protozoan that ranges from 15 to 25 microns in diameter, can contain up to eight nuclei in mature cysts.How would the karyosome expect to appear on a stained slide?

Accepted Answer

A)   Small, usually compact
B)   Large, usually compact
C)   Small, irregularly shaped
D)   Large, not compact

Question 20

The cyst form of Balantidium coli is the infective stage.It has one large kidney-shaped macronucleus and one small, round micronucleus.The troph is quite large, measuring 50 to 150 microns in length and 40 to 70 microns in width.What single feature is associated with this organism?

Accepted Answer

A)   Falling leaf motility
B)   Shepherd's crook
C)   Presence of oocytes
D)   Cilia covering the troph

Exam 47: Intestinal Protozoa