When is acid fast staining used

The decolorised non-acid-fast cells are able to take up the methylene blue counterstain, and therefore stain blue. The rod-shaped acid-fast bacteria that resisted decolorisation, however, will stain red-pink, the color of the initial carbol fuchsin stain. The ZN method continues to remain a reliable and effective way to demonstrate the acid-fast bacteria, and it is used for both research and diagnostic purposes.

Researchers studying acid-fast organisms, such as members of the genus Mycobacterium and Nocardia , will use this staining technique routinely to examine sections to evaluate the bacteria in certain tissues.

The AF stain is also used diagnostically by pathologists to identify these organisms, and is an especially important technique in the diagnosis of tuberculosis. It is also used in the diagnosis of other mycobacterial diseases, including leprosy due to infection with Mycobacterium leprae. Want to know more about histology? Visit the Bitesize Bio Histology Hub for tips and trick for all your histology experiments.

Has this helped you? Then please share with your network. You must be logged in to post a comment. The acid-fast stain is a laboratory test that determines if a sample of tissue, blood, or other body substance is infected with the bacteria that causes tuberculosis TB and other illnesses. Your health care provider will collect a sample of urine, stool, sputum, bone marrow, or tissue, depending on the location of the suspected infection.

The sample is then sent to a laboratory. Some of the sample is placed on a glass slide, stained, and heated. The cells in the sample hold onto the dye. The slide is then washed with an acid solution and a different stain is applied.

Bacteria that hold onto the first dye are considered "acid-fast" because they resist the acid wash. These types of bacteria are associated with TB and other infections. The amount of discomfort depends on how the sample is collected. Your provider will discuss this with you. The test can tell if you are likely infected with the bacteria that cause TB and related infections.

Omitting the step could lead to false results since the cabolfuchsin might be de-colorized leading to false negative results. Both acid fast and non-acid fast cells could take the counter stain and interfere with the end results. Nice explanation of the principle. You just boost my understanding of this topic. But what are the acid-alcohol fast bacilli? These have athuck cell wall. Have more mycolic acids and wax.

Studying Medical Lab Technician. You did well in your explaination, very helpful. B Mycobacterium, since its staining meth is for differenciation, and so, is it a gram pos or neg? OK Thanks you sir. But you mean no need of malachites green when methylene blue is available??? James Adekeye thanks for your explanation. What happens if we overheat the slide?

Heating simple helps in the enhancement on the penetration of the carbol fuchsin primary dye into the cytoplasm. This then makes the organism colour red.. I am currently working on an unknown microbe project in my Micro class. I wanted to know what are the confirmation test for Mycobacterium smegmatis after acid-fast stain? Please what is the function of counter stain in Ziehl Neelsen staining, because I read the function differs from that of gram staining. Am pascal studying medical lab in technical university Kumasi Ghana.

I need clarification on the acid fast stain. First section says to use methylene blue, but next section says malachite green. What am I missing?? Is it for different specimens? Thanks much. Your website is awesome! Methylene blue and malachite green are used as background stains, so you can use either one of them not both. Then obviously the colour of your background will depend on the colour of the stain used. Am Webster, medical laboratory technician very desperate to upgrade myself to a scientist.

The above discussion had been very much educative and it reminded me of my days in the university especially during my industrial training at Adamawa Hospital Yola, Nigeria. Microbiology is an intersting field of study that touches every aspect of human life. I used this book during my studies and it helped me so greatly. Hello, Thanks for the suggestion. Procedure has been corrected from the book of Monica Chessebrough. Great work Sagar.

You only need to highlight how you prepare the smear. Try these reference materials Microbiology by Monica Chessebrough volume 1and 2. I believe it will be of great help as a microbiologist. Well done Mr. Your explanation of the principle and procedure for Acid fast staining were basically correct.

Similarly in your steps 4 and 6, it is advisable you rinse rather than wash the slide to avoid removing the smear itself. Rinsing the slide will remove the excess unattached stains from the smear and the slide.