Acid-fast stain is a differential stain used to identify acid-fast organisms such as members the the genus Mycobacterium. Acid-fast organisms are characterized by wax-like, nearly impermeable cabinet walls; castle contain mycolic mountain and huge amounts of fat acids, waxes, and facility lipids. This kind of cell wall is resistant to many compounds, therefore acid-fast organisms require a distinct staining technique.

You are watching: S. epidermidis acid fast stain

The major stain supplied in acid-fast staining, carbol fuchsin, is lipid-soluble and contains phenol, which help the stain penetrate the cabinet wall. This is more assisted by the addition of heat in the kind of warm (steam). Heavy steam helps to ease up the waxy layer and also promotes entrance of the major stain inside the cell. The smear is then rinsed through a very solid decolorizer, which strips the stain from all non-acid-fast cells however does not permeate the cell wall of acid-fast organisms. The decolorized non-acid-fast cells then take increase the counterstain, i m sorry in our situation is methylene blue.


1. Working in pairs, prepare three slides as directed below (2 for back-up and also one come stain).

2. Brand each slide and also draw a circle on the facility of the slide v a wax pencil.

3. Prepare an emulsion on every slide through 4 loopfuls of Staphylococcus epidermidis from your broth culture onto the on slide (these will be your acid-fast an unfavorable bacteria).

4. Then, include one loopful the Mycobacterium chelonae (these are your acid fast positive bacteria) and also mix the 2 bacteria together.

5. Permit the slide(s) come air dry on the slide warmers (while these slides space drying, prepare your slides for the spore stain).

6. As soon as the liquid has totally evaporated, warm fix the bacteria by passing it with your flame three times.

7. Make sure the on slide rack on height of your beaker is fully level. Then, lug your water to cook while the slides space drying.

You just need around 200 milliliters of water. If you include more, you will certainly be wait all lab period for your water come boil.

8. When the water is boiling, location your slide on the slide rack above the cook water.

9. Covering the area of her smear on the slide with a square item of PRECUT document towel. Make sure none of the record is hanging turn off the slide.

10. Carefully use the CARBOL FUCHSIN stain come the paper towel.

If a stain appears in the water you room boiling, please stop and also discard the stained water in the liquid waste disposal. The fumes indigenous carbol fuchsin have the right to be toxic.

11. Heavy steam with the stain top top the slide for 7 minutes while repeatedly applying much more stain therefore the paper square never ever dries out.

12. Gently eliminate the file with forceps and discard it in the little waste file cup that will certainly be provided on her bench. Then, rinse the slide with water.

13. Put the on slide on your staining basin and gently rinse with water.

14. Decolorize with 6 autumn of mountain alcohol (not ethanol from your gram stain kit), climate rinse v water.

15. Counterstain through methylene blue for 2 minutes.

16. Rinse through water and blot dry with bibulous document (do not usage the slide warmer).

17. Examine under the 100X objective lens with oil immersion and also record your results.

api/deki/files/20240/clipboard_e0a08d1886a336e52f8ced85b3502ae3e.png?revision=1&size=bestfit&width=722&height=424" />

18. Prepare two slides v emulsions one from plate A and one native plate B.

19. Warmth fix the slides and place lock on the on slide rack above the cook water.

20. Sheathe the area of her smear on every slide through a square piece of PRECUT record towel.

21. Carefully use the MALACHITE environment-friendly stain come the document towel.

22. Vapor for 10 minutes and keep the paper soaked v the stain throughout this time.

23. Gently eliminate the file with forceps, discard in the small waste file cup that will certainly be provided on her bench, and also then rinse the slide v water.

24. Put the slides on her staining basin and also gently rinse with water.

25. Counterstain through SAFRANIN because that 1 minute and then rinse through water. Blot dry v bibulous paper.

26. Examine under the 100X target lens v oil immersion and record her results.

See more: Is Digesting Food Endothermic Or Exothermic, Is Cooking Endothermic