Corynebacterium diphtheriae

Question 1

C. diphtheriae causes diphtheria via?

Answer 1

Exotoxin encoded by Beta-prophage

Question 2

Characteristics of C. Diphtheriae?

Answer 2

• Gram +
• Club shaped rods
• Catalase positive
• Aerobic

Question 3

What media do you use to culture C. diphtheriae?

Answer 3

• Lofflers’ Meida and CTBA (Cysteine-Tullurite Blood Agar) to get black colonies

Question 4

What is the mechanism of action of Diphtheria toxin?

Answer 4

Inactivates elongation factor (EF-2)

Question 5

What are the symptoms of Diphtheria toxin?

Answer 5

• Pharyngitis with pseudomembranes in throat
• Severe lymphadenopathy (Bull Neck)
• recurrent laryngeal nerve palsy

Question 6

Diphtheria toxin (A&B) is encoded by what?

Answer 6

a lysogenic bacteriophage. Only strains infected by this phage can produce toxin and cause diphtheria.

Question 7

What is the role of the B subunit of Diph. Toxin?

Answer 7

binds to receptor on host epithelial cell

Question 8

What is the role of A subunit of Diph Toxin?

Answer 8

(enzymatic portion) it targets EF-2 elongation factor

Question 9

What bacteria have toxins which are ADP ribosylating A-B toxins?

Answer 9

1. Corynebacterium diphtheriae (Diphtheria Toxin)
2. Pseudomonas aeuriginosa (Exotoxin A)
3. E. Coli (Heat labile toxin)
4. Vibrio cholerae (Cholera toxin)
5. Bordetella pertussis (Pertussis toxin)

Question 10

Diphtheria only affects who?

Answer 10

Unimmunized People

Question 11

What test do you do for Diph Toxin production?

Answer 11

Elek Test

Question 12

What vaccine prevents diphtheria and provides lifetime immunity to diphtheria toxin?

Answer 12

DTap Vaccine (Diphtheria, Tetanus, Pertussis) 
- Aka: Beta Subunit (Toxoid vaccine)

Question 13

What is the drug treatment for C. Diphtheriae?

Answer 13

• Antitoxin

- Erythromycin