Fite Acid-Fast Stain for Leprosy organisms is used to detect which organism?

• A. Mycobacterium leprae
• B. Mycobacterium tuberculosis
• C. Nocardia
• D. Treponema pallidum

Answer: (A)

Fite acid-fast staining is a modified, gentler acid-fast technique used to visualize organisms with a mycolic-acid–rich cell wall that can be destroyed by the harsher decolorizers in standard acid-fast stains. The organism most detectable with this method is Mycobacterium leprae, the cause of leprosy, because it is particularly weakly acid-fast and fragile in tissue. The milder decolorization step helps retain the stain in the bacilli, allowing them to stand out as red rods against a blue counterstain in skin or tissue samples.

Tuberculosis bacteria are usually stained with the standard acid-fast methods like Ziehl-Neelsen. Nocardia can be variably acid-fast with modified stains, but Fite staining is specifically associated with leprae in clinical practice. Treponema pallidum is not acid-fast and is identified by other methods such as dark-field examination or special stains/immunostaining.