Jun 10 • Multiple choice answers
🧪 Answer Reveal: Recall Poll #1
Question: Which feature is most characteristic of Corynebacterium diphtheriae?
✅ Correct Answer: B) Metachromatic granules
👏 Shoutout to the member who voted and got it right! 🎉
🧠 Explanation:
One of the classic identifying features of Corynebacterium diphtheriae is the presence of metachromatic (Babes-Ernst) granules.
These granules are intracellular phosphate storage granules that can be visualized with special stains such as:
🔬 Albert stain
🔬 Methylene blue stain
High-Yield Clues for
C. diphtheriae
✔ Gram-positive rod
✔ Club-shaped appearance
✔ “Chinese letters” or palisading arrangement
✔ Metachromatic granules
✔ Produces diphtheria toxin
❌ Why not the other options?
A) Beta-hemolysis on blood agar
• Not a defining characteristic of C. diphtheriae
C) Lactose fermentation
• More commonly used when identifying Gram-negative enteric organisms
D) Oxidase positivity
• Not a key identifying feature of C. diphtheriae
💡 Quick Recall Tip
👉 Corynebacterium = Club-shaped rods + Chinese letters + Metachromatic granules
If you see those granules on an exam question, Corynebacterium diphtheriae should immediately come to mind!
👇 Did you get it right before seeing the answer?
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🧪 Answer Reveal: Recall Poll #1
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