MICROSCOPIC IDENTIFICATION OF PROTOZOA - SALINE WET MOUNT (Using Lugol’s Iodine)

MICROSCOPIC IDENTIFICATION OF PROTOZOA

SALINE WET MOUNT (Using Lugol’s Iodine)

·      Saline wet mount is made by mixing a small quantity (about 2 mg) of feces in a drop of Saline placed on a clean glass slide. The smear is then examined under a microscope.

·      Saline wet mount is used for the detection of Trophozoites and Cysts of Protozoa, and Eggs and Larvae of Helminths.

·      It is particularly useful for the detection of live motile Trophozoites of Entamoeba histolytica, Giardia lamblia and Balantidium coli.

Materials Required

a)     Normal Saline (0.85 % NaCl)

b)     Lugol’s Iodine

c)     Glass slide

d)     Coverslips

e)     Pipettes

f)      Microscope   

Procedure

·      Take a clean Microscope slide.

·       Place a drop of Saline in the center of the left half of the Glass slide.

·       Place a drop of Lugol’s Iodine solution in the center of the Glass slide.

·       With an applicator stick, pick up a small portion of faeces and add it to the drop of Saline. Add a similar portion to the drop of iodine. Mix the faeces with the drops to form suspensions.

·       Cover a drop with a Coverslip onto the slide so that air bubbles are not produced.

·       Examine the specimen with the low power objective (40 x) and low light. 

Observation

                      Trophozoite of Protozoa                       

Cyst of Protozoa

Limitations of Iodine Wet Mount

·       Once Iodine is added to the preparation, the organism will be killed and motility will be lost.

·       Oil immersion examination is not recommended (organism morphology not that clear)