A throat swab from a child with pharyngitis shows Gram-positive bacilli with clubbed ends. Which stain best demonstrates the metachromatic volutin granules characteristic of this organism?
- A Giemsa stain
- B Ziehl-Neelsen stain
- C Albert stain ✓
- D Acridine orange stain
Correct answer: C. Albert stain
Explanation
Albert stain demonstrates the metachromatic volutin (polymetaphosphate) granules of Corynebacterium diphtheriae, which appear bluish black against a green cytoplasmic background. The organism itself stains green with dark granules at the poles. Ziehl-Neelsen is for acid-fast bacilli, Giemsa for malaria parasites and Chlamydia inclusion bodies, and acridine orange is a general nucleic acid fluorescent stain that does not specifically highlight volutin granules.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.