On examination of a 6-year-old child the doctor noticed grayish film on the child’s tonsils. Microscopy of the smears stained by Neisser method detected there Corynebacterium diphtheriae. What morphologic feature was the most indicative for determining the type of the agent?

Answer options

1. Polar placement of volutin granules
2. Presence of the capsule
3. Fence-like position of the agent’s cells
4. Spores that exceed cells in diameter
5. Localization of the causative agent within macrophages

Explanation

On examination of a 6-year-old child the doctor noticed grayish film on the child’s tonsils. Microscopy of the smears stained by Neisser method detected there Corynebacterium diphtheriae. What morphologic feature was the most indicative for determining the type of the agent?Volutin granules are used as one of the identifying criteria when attempting to isolate Corynebacterium diphtheriae on Löffler's medium.