Gut protozoa

Question 1

What is this?

Answer 1

Entamoeba Histolytica/Dispar cysts

10-15μm

Question 2

How do you differentiate between immature and mature Entoamoeba Histolytica/Dispar cysts ?

Answer 2

Mature cysts have 4 nuclei; immature cysts have only I or 2 and may have glycogen present

Question 3

What is this?

Answer 3

E.Histolytica/Dispar trophozoite

20x25μm

Question 4

What is this?

Answer 4

Entamoeba Coli cyst

15 - 25μm

Usually contain 1 - 8 nuclei with irregular peripheral chromatin

Question 5

What is this?

Answer 5

E.Nana cyst

7.5-10μm

Cysts of E.nana are small ; round or oval, with four hole-like nuclei, and a large eccentric karyosome

Question 6

What is this?

Answer 6

Giardia Lamblia cyst

10-15μm

• oval with a smooth wall
• 2-4 nuclei, often grouped at one end (often not visible in saline)
• an axostyle (slightly S-shaped line) can often be seen

Question 7

Who is more likely to pass an amoebiasis infection to others?
A patient with amoebic dysentery
OR
An asymptomatic patient?

Answer 7

The asymptomatic patient

They are likely to be releasing formed stool more likely to harbour mature cysts. The diarrhoeic stool in acute
amoebic dysentery is more likely to harbour trophozoites and perhaps some immature cysts

Question 8

What is this?

Answer 8

Entamoeba Coli cyst

15 - 25μm

Usually contain 1 - 8 nuclei with irregular peripheral chromatin

Question 9

What is this?

Answer 9

Giardia trophozoite

usually 12-15x5-9μm

Question 10

What is this?

Answer 10

Giardia cyst

10-15μm

• oval with a smooth wall
• 2-4 nuclei, often grouped at one end (often not visible in saline)
• an axostyle (slightly S-shaped line) can often be seen

Question 11

What is this?

Answer 11

Cyclospora

8-10 μm

Oocyst with 2 sporocysts

Question 12

What is this?

Answer 12

Isospora

25–35 μm

Oocyst

Question 13

What is this?

Answer 13

Blastocystis hominis

Wide size variation, most between 4 and 15 μm

vacuolar form,
“signet ring”

Question 14

What is this?

Answer 14

Chilomastix cyst

7-9μm

(non-pathogenic)
pear/lemon shaped

Question 15

What is this?

Answer 15

E.coli cyst

15-25 µm

Large, round cyst with well-defined membrane.
mostly clear nuclei (more than 4 and up to 8)
usually mature cysts
(can have irregular peripheral chromatin)

Question 16

What is this?

7-9µm

Answer 16

E.nana cyst

7-9 µm

Small
Oval or round in shape
4 hole-like nuclei (not always clear)

Question 17

What is this?

Answer 17

Giardia cyst

10-12.5µm

Oval shaped cyst
possible S shaped axostyle may be seen
two nuclei can be visible

Question 18

What is this?

10-15 µm

Answer 18

E.histolytica/dispar

10-15 µm

Round cyst with 3 (1-4) nuclei

*some cysts can be immature with glycogen or chromidial bars present.