Which organism is commonly demonstrated using the Fite modification?

• A. Mycobacterium leprae
• B. Mycobacterium tuberculosis
• C. Staphylococcus aureus
• D. Candida albicans

Answer: (A)

Fite modification is a specialized acid-fast staining approach used to visualize Mycobacterium leprae in tissue. This organism has a very lipid-rich, fragile cell wall and tends to be difficult to detect with standard acid-fast methods in fixed tissue sections. The Fite method uses a gentler decolorizing step and lipid-preserving reagents so the red carbol fuchsin stain remains in the bacilli, highlighting Mycobacterium leprae as red rods against a blue counterstained background. This makes it the classic stain for leprosy in skin smears and nerve/tibial biopsies. The other organisms listed aren’t demonstrated with this modification because they don’t require or respond to this gentler approach, and some aren’t acid-fast at all.