A 4-year-old girl is brought to the physician with progressively worsening fever, malaise, and a sore throat. Her parents say "Our daughter has not received vaccinations because her body has to learn how to fight infections." Her temperature is 38.5C (101.3 F). Physical examination shows marked cervical lymphadenopathy. There are gray-white membranes over the tonsils and posterior pharynx that bleed when scraped off. A sample of the pharyngeal exudate is obtained by oropharyngeal swab. Bacteria isolated from the exudate demonstrate exotoxin production in the laboratory. Which of the following best describes the mechanism of action of the exotoxin?

Question

A 4-year-old girl is brought to the physician with progressively worsening fever, malaise, and a sore throat. Her parents say "Our daughter has not received vaccinations because her body has to learn how to fight infections." Her temperature is 38.5C (101.3 F). Physical examination shows marked cervical lymphadenopathy. There are gray-white membranes over the tonsils and posterior pharynx that bleed when scraped off. A sample of the pharyngeal exudate is obtained by oropharyngeal swab.  Bacteria isolated from the exudate demonstrate exotoxin production in the laboratory.  Which of the following best describes the mechanism of action of the exotoxin?

Quizplus · Accepted Answer

Eductional Objective: Diphtheria toxin is an AB exotoxin that ribosylates and inactivates elongation factor-2.  This action inhibits protein synthesis and ultimately leads to cell death.

A 4-Year-Old Girl Is Brought to the Physician with Progressively