The acid-fast stain is primarily used to identify the organism responsible for which disease?

The acid-fast stain is primarily used to identify the organism responsible for which disease?

• A. Anaplasmosis
• B. Colibacillosis
• C. Ringworm
• D. Tuberculosis

Answer: (D)

Acid-fast staining targets organisms with a waxy, mycolic-acid–rich cell wall. That lipid-rich layer resists decolorization by acid alcohol, so these bacteria keep the red dye and appear bright red under the microscope. This property is most famously seen in Mycobacterium species, which include the causative agent of tuberculosis, making the stain primarily used to identify tuberculosis. The other listed diseases are caused by organisms that don’t have this waxy cell wall (fungi or typical Gram-negative bacteria), so they aren’t reliably detected with an acid-fast stain. Hence, tuberculosis is the disease most associated with this staining method.

Acid-fast staining targets organisms with a waxy, mycolic-acid–rich cell wall. That lipid-rich layer resists decolorization by acid alcohol, so these bacteria keep the red dye and appear bright red under the microscope. This property is most famously seen in Mycobacterium species, which include the causative agent of tuberculosis, making the stain primarily used to identify tuberculosis. The other listed diseases are caused by organisms that don’t have this waxy cell wall (fungi or typical Gram-negative bacteria), so they aren’t reliably detected with an acid-fast stain. Hence, tuberculosis is the disease most associated with this staining method.