Now let us look at acid past staining. We will first study acid fast procedure, then the microorganisms that are stained as acid fast. And finally we will look at the reasoning behind the acid fast staining. Acid fast procedure starts with preparing a smear of bacterial cells and heat fixing them to the slide. Then, the slide is flooded with carpal foots in about three to four drops and let the stain remain for about one minute. After removing excess stain by tilting the slide the slide is wins gently with us.

Alcohol for about 30 seconds. The slide is then reinstalled again and blotted gently. Then the slide is flooded with methylene blue for at least a minute. The slide is then rinsed and blotted dry and observed under the scope acid past cells stain in pink. Whereas non acid pass cells stain in blue. There are two main types of bacterial cells that can be stained by acid fast stains.

Those are the nocardia species and the mycobacteria species. Both bacteria are under the phylum Actonel bacteria nakara nocardia causes lokar Diaz's, which affects mainly the lungs but it can spread to the brain and skin. The mycobacteria has several species. That is the genus mycobacteria has several species that we are familiar with mycobacterium tuberculosis causes tuberculosis mycobacteria leprae causes leprosy also known as Hansen's disease nowadays mycobacteria this magnet is not considered a pathogen, but it is used in the laboratory often when a typical mycobacteria is the mycobacteria. avium complex also known as Mac nocardia. Now why shown here by acid fast stain has this thin, elongated structures mycobacterium tuberculosis are seen as vast Li, this thin, Rod shaped bacteria.

These are found within macrophages in the lung. scene here are the nucleus of the macrophages and the rest is the cytoplasm. The nucleus in dark blue and the cytoplasm containing the bacteria. Mycobacterium avium complex smack with acid fast stain often has the characteristic appearance shown here with numerous mycobacteria, filling the macrophages. Again shown here is the nucleus and the cell which can be delimited pretty Much by the bacteria themselves. Some bacteria such as those of the General mycobacteria nocardia have a waxy slight impermeable cell wall containing unusual fatty acids known as Nikolic acid carpel fixing the primary stain is lipid soluble and it contains phenol.

This aided by the stain to penetrate the waxy cell wall, the heat also assists in the process. So, the fact that carbon fixation is lipid soluble and contains phenol aids in many upgrading the cell wall and the heat aids in this process. The D colorizer strips the stain from non acid fast sts cells, but not from the acid fast cells. Non acid fast cells are then have to be counter stained with methylene blue. So, in summary acid fast stain is accomplished by heat fixing the smear of bacterial cells onto a slide and then flooding them with car ball fixing. This stains all cells in pink.

After washing the slide is flooded with acid alcohol washed again and then counter stain with a secondary stain which is methylene blue at this point the non acid plastic cells stain in blue The main asset class bacteria, nocardia, and mycobacteria species. The reasoning behind the acid fast stain is due to the fact that these bacteria have a waxy lipid cell wall, containing mainly my colic acid concludes our study of the asset class staining