Fluoroquinolones · Pharmacology

Which of the following mechanisms contributes to 'plasmid-mediated' quinolone resistance?

  1. Secretion of extended-spectrum beta-lactamase enzymes
  2. Synthesis of a new cell wall layer
  3. Qnr proteins that protect DNA gyrase from binding
  4. Inactivation of the drug by bacterial esterases
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Correct answer: Qnr proteins that protect DNA gyrase from binding

Qnr proteins are plasmid-mediated factors that physically protect DNA gyrase from the quinolone molecule. While they usually provide only low-level resistance, they facilitate the selection of high-level chromosomal mutations.

Difficulty: Medium Question 19 of 20

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