Sketchy Micro: Corynebacterium Diphtheriae

Question 1

Histologically, how might Corynebacterium be described?

Answer 1

It is a Gram-positive rod that stains metachromatic with aniline dyes.

(Think of the violet stadium paint and the maracas –the maracas are meant to help you think of the possible description as “club-shaped.”)

Question 2

The rods of C. diphtheriae often grow in what pattern?

Answer 2

V- or Y-shaped divergences

Think of the zig-zag design on the maraca.

Question 3

Describe the two toxins of Corynebacterium diphtheriae.

Answer 3

Toxin A: active subunit; binds to elongation factor 2 and ADP-ribosylates it

Toxin B: binding subunit

(Think of the guy playing the accordion: the instrument can ELONGATE, and he’s wearing the ri-bow-sylation bowtie.)

Question 4

C. diphtheriae is transmitted by ____________ and causes this characteristic sign: ______________.

Answer 4

respiratory droplets; the thickened “bull’s neck,” due to lymphadenitis

(Think of the bull –with his massive neck –shaking nasty snot droplets everywhere.)

Question 5

What is the most common cause of death in Corynebacterium diphtheriae infection?

Answer 5

The cardiotoxic effects: arrhythmia, heart block, and myocarditis

(Think of the bull fighter with his heart-shaped cape.)

Question 6

What common pathologic effect do Corynebacterium diphtheriae and Clostridium difficile have?

Answer 6

Both cause a pseudomembrane due to death of epithelial cells: C. diphtheriae in the oropharynx and C. difficile in the intestines.

(Think of the kids with their MEMBRANE-wrapped cotton candy.)

Question 7

How does Corynebacterium cause paralysis?

Answer 7

It damages the myelin of peripheral motor neurons (symbolized by the nerve-shaped sausages that the man in the audience is eating).

Question 8

What two media can grow C. diphtheriae?

Answer 8

Tellurite (like the Telescreen showing the performance) and Loeffler’s (like the kid laughing at the performance)

Question 9

You can use the _____________ to test for C. diphtheriae toxin.

Answer 9

Elek’s test

Question 10

Why might a question about C. diphtheriae include an immigrant?

Answer 10

Because all children in the U.S. are vaccinated for diphtheria

Question 11

What kind of vaccine is diphtheria?

Answer 11

A vaccine against the toxin (aka a toxoid)

Think of the green needles, which are the same color as the accordion-player’s bowtie.