Page 291 - parasitology for medical and clinical laboratoryprofessionals

Laboratory Procedures for Identifying Parasitic Organisms and Their Ova 271

Equipment and Supplies
1. Protective gloves and disposable gown
2. Applicator sticks
3. Standard microscope slides
4. Fresh fecal sample

5. Schaudinn fixative solution (without acetic acid)
6. 70% and 90% ethyl alcohol (ethanol)

7. Acidified 90% ehtanol
8. Absolute ethanol
9. Trichrome stain
10. PVA fixative for diarrheic stools

11. Xylene or xylene substitute
12. Permount
13. #1 cover glasses
°
14. Slide warmer or 37 C incubator
15. Immersion oil
16. Microscope
Procedural Steps
1. For a fresh stool sample, applicator sticks or similar implements may be used to
smear the specimen as a thin smear of fresh feces on a 1 3 3-in. microscopic
slide. Do not allow the smear to dry before initiating the staining procedure.
°

2. Place the moist smear in Schaudinn fixative solution for 5 minutes at 50 C or for
1 hour at ambient (room) temperature.

3. Rinse the slide in 70 percent alcohol for 5 minutes but avoid fixation of the

smear for PVA-fixed material.
4. For PVA-preserved specimens, a few drops of the sample should be placed on
absorbent filter paper for approximately 3 minutes and allowed to drain before

collecting the material from the paper. Do not allow the specimen to dry before
making a smear!
5. Using an applicator stick, prepare a smear as in Step 1 on a 1 3 3-in. micro-
scopic slide.
4. Allow the smear to air dry overnight at room temperature or for 2 to 3 hours on
°
°
a 37 C on a slide warmer or a 37 C incubator. If slides are dried too quickly, dis-
tortion of the morphology of the organism(s) may occur. But thorough drying is
essential to prevent sloughing off of the material during the staining process.
5. Place the smear in 70 percent ethanol with enough iodine to make the solution
the color of strong tea, for 2 to 3 minutes. A 10-minute period is required if the
smear is PBA-fixed.

6. Place slide in two changes of 70 percent alcohol solutions for 5 minutes in each
solution.
(continues)