What is the morphology of C. diphtheriae?

What is the morphology of C. diphtheriae?

• A. Gram-negative, motile rods
• B. Gram-positive, non-motile rods
• C. Gram-positive, motile cocci
• D. Gram-negative, non-motile cocci

Answer: (B)

Corynebacterium diphtheriae is best characterized by its Gram-positive, non-motile rod morphology. This bacterium is part of the group of organisms known as diphtheroids and is the causative agent of diphtheria. Under the microscope, C. diphtheriae appears as rod-shaped cells that often display a characteristic club-like shape, and they can be seen forming palisades or "Chinese letter" arrangements. The Gram-positive nature of C. diphtheriae indicates that it has a thick peptidoglycan layer in its cell wall, which retains the crystal violet stain used in the Gram staining process. This property is important as it distinguishes it from Gram-negative organisms, which would not retain the violet stain and appear red or pink due to the counterstain applied. Additionally, it is non-motile, meaning it does not have flagella and does not exhibit movement on its own, which is another important differentiating factor. Understanding the specific morphology and characteristics of C. diphtheriae is crucial for identification in the laboratory setting and aids in proper diagnosis and treatment of infections caused by this bacterium.

Corynebacterium diphtheriae is best characterized by its Gram-positive, non-motile rod morphology. This bacterium is part of the group of organisms known as diphtheroids and is the causative agent of diphtheria. Under the microscope, C. diphtheriae appears as rod-shaped cells that often display a characteristic club-like shape, and they can be seen forming palisades or "Chinese letter" arrangements.

The Gram-positive nature of C. diphtheriae indicates that it has a thick peptidoglycan layer in its cell wall, which retains the crystal violet stain used in the Gram staining process. This property is important as it distinguishes it from Gram-negative organisms, which would not retain the violet stain and appear red or pink due to the counterstain applied.

Additionally, it is non-motile, meaning it does not have flagella and does not exhibit movement on its own, which is another important differentiating factor. Understanding the specific morphology and characteristics of C. diphtheriae is crucial for identification in the laboratory setting and aids in proper diagnosis and treatment of infections caused by this bacterium.