Page 74 - MNUmicrobiology practical 2025

General Microbiology & Immunology (PM 401) second level Semester 4 2024/2025

-Methylene blue [counterstain]

5- Inoculating loop

6-Bunsen burner

7- Slide holder.

8- Staining rack

9- Washing water

10- Microscope with oil immersion lens

11- Marker pen

Acid fast staining steps

1- Prepare of bacterial smear

2- Flood the smear with the primary stain

(carbol fuchsin), place it in a boiling

water bath over hot plate, and let it sit

for 5 minutes (gentle heat or steam act

as a mordant as it helps in penetration

and retention of dye)

3- Reapplying stain if it begins to dry out

4- Let the glass slide cool and wash the smear with slow-running water

5- Decolorize with 6 drops of acid alcohol for 10 – 15 seconds, then rinse with
water.

6- Flood slide with counterstain, Methylene blue, for one minute and then rinse.
7- Gently blot the slide dry. It is now ready to be viewed under oil immersion

General Microbiology & Immunology (PM 401) Practical note Page 63