Question 1

Which of the following is a key virulence factor of *Corynebacterium diphtheriae* that leads to inhibition of protein synthesis in host cells?

Accepted Answer

Diphtheria toxin

Question 2

The diphtheria toxin consists of two subunits, A and B. What is the primary function of the A subunit?

Accepted Answer

Catalyzing the destruction of elongation factor 2 ($EF2$)

Question 3

A child presents with a thick pseudomembrane in the pharynx and respiratory distress. Which diagnostic test is most specific for confirming *Corynebacterium diphtheriae* infection?

Accepted Answer

Elek immunodiffusion assay

Question 4

Why is the DTaP vaccine effective in preventing diphtheria?

Accepted Answer

It induces immunity against the diphtheria toxin

Question 5

Which of the following best describes the mechanism by which diphtheria toxin causes cell death?

Accepted Answer

Destroys elongation factor 2 ($EF2$), halting protein synthesis

Question 6

A patient with untreated diphtheria develops myocarditis and peripheral neuropathy. What is the most likely cause of these complications?

Accepted Answer

Systemic absorption of diphtheria toxin

Question 7

Which laboratory medium is used to identify *Corynebacterium diphtheriae* based on its unique colony morphology?

Accepted Answer

Loeffler’s medium

Question 8

What is the primary mode of transmission for *Corynebacterium diphtheriae*?

Accepted Answer

Respiratory droplets

Question 9

Which of the following is NOT a characteristic feature of *Corynebacterium diphtheriae*?

Accepted Answer

Endospore formation

Question 10

A physician suspects diphtheria in a child with pharyngitis and fever. Which treatment should be administered to neutralize the toxin?

Accepted Answer

Antitoxin

Question 11

Which process allows *Corynebacterium diphtheriae* to form V-shapes and palisade arrangements?

Accepted Answer

Snapping division

Question 12

What is the role of metachromatic granules in *Corynebacterium diphtheriae*?

Accepted Answer

Storage of phosphate

Question 13

Which of the following best explains why diphtheria is more severe in non-immune patients?

Accepted Answer

They lack antibodies to neutralize the diphtheria toxin

Question 14

Which of the following is a direct consequence of pseudomembrane formation in diphtheria?

Accepted Answer

Obstruction of respiratory passages

Question 15

Why is erythromycin used in the treatment of diphtheria?

Accepted Answer

It inhibits bacterial protein synthesis

Gram-Positive Pathogens: High G+C Bacteria (Corynebacterium)

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