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.
Conventional smear microscopy with the Ziehl-Neelsen (ZN) stain is a rapid and practical method for detecting acid-fast bacilli (AFB), especially in low-income countries, due to its rapidity, low cost, and high positive predictive value for tuberculosis (14).
Acid-Fast Bacteria—Ziehl– Neelsen Stain This stain is used to identify Mycobacterium tuberculosis, the causative agent of tuberculosis. Acid-fast organisms have a lipoid capsule that has a high molecular weight and is waxy at room temperature. This makes the organism impenetrable by aqueous-based staining solutions.
Microscopic examination of clinical samples for acid-fast bacilli using the Ziehl-Neelsen (ZN) stain has been a standard diagnostic tool and is used globally for rapid TB diagnosis. Microscopy can detect 60% to 70% of culture-positive samples with a lower limit of detection of 5 × 103 organisms/mL.
Mycobacterium tuberculosis is diagnosed using the Ziehl-Neelsen Stain/Acid-Fast Stain which differentiates acid-fast from non-acid-fast bacilli.
Ziehl-NeelsenAbstract. The diagnosis of mycobacterial infection depends on the Ziehl-Neelsen (ZN) stain, which detects mycobacteria because of their characteristic acid-fast cell wall composition and structure.
The most commonly used diagnostic tool for tuberculosis is a skin test, though blood tests are becoming more commonplace. A small amount of a substance called tuberculin is injected just below the skin on the inside of your forearm. You should feel only a slight needle prick.
Ziehl Neelsen Acid-fast stainStep 2: Smear Preparation (Review) ... Cover the smear with carbolfuchsin dye. ... Dry heat for 2 minutes.Cool and rinse with water. ... Wash the top and bottom of slide with water and clean the slide bottom well.Counterstain with Methylene Blue for 30 seconds to 1 minute.