Med Micro 3603 Test 2

Front 1

What does the gram stain look like in Corynebacterium

Back 1

In young cultures the organism is Gram positive and rod shaped. As cultures age, the organisms tend to become gram negative and pleomorphic.
-Metachromatic granules (Babes-Ernst bodies), due to accumulations of polymerized polyphosphates, result in a beaded appearance upon methylene blue staining.

Front 2

Describe Corynebacterium microscopic features

Back 2

‘Coryne’ means club in reference to the swellings and irregular shape of the cells and the picket fence arrangement (also termed Chinese character and pallisade) help identify this organism. This unusual arrangement is due to ‘snapping’ movement during cell division

Front 3

What is the genus and species of the organism that causes diphtheria?

Back 3

Corynebacterium diphtheriae

Front 4

Describe the microscopic appearance of Corynebacterium when grown on Loefflers media

Back 4

Growth on Loeffler medium enhances pleomorphism since it’s a nutritionally deficient medium that leads to an unbalanced cell wall synthesis.

Front 5

What is the major pathogenic component of Corynebacteria diptheriae?

Back 5

toxin production