🦠microbiology review

Diptherioids

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Diphtheroids are a group of non-pathogenic bacteria resembling Corynebacterium diphtheriae. They are part of the normal microbiota in various body sites, including the digestive tract.

5 Must Know Facts For Your Next Test

  1. Diphtheroids are commonly found in the human digestive system and play a role in maintaining microbial balance.
  2. Although they resemble pathogenic species, diphtheroids are generally non-pathogenic and do not cause disease.
  3. They can sometimes be mistaken for Corynebacterium diphtheriae in laboratory settings due to their similar morphology.
  4. Diphtheroids contribute to the prevention of colonization by harmful pathogens in the digestive system.
  5. They are Gram-positive rods, often appearing club-shaped or irregular under microscopic examination.

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