Antimicrobials - Nucleic Acid Synthesis Inhibitors Flashcards

1
Q

What is the mechanism of action of fluoroquinolones (1st gen ciprofloxacin, 2nd gen levofloxacin)?

A
  • inhibits action of DNA gyrase (cipro) + topoisomerase IV (levo)
  • this interferes with DNA synthesis
  • works exclusively in G- bacteria
  • levofloxacin also works for drug resistant S. pnuemoniae
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2
Q

What are the main mechanisms of resistance to fluoroquinolones?

A
  • alteration of binding site on DNA gyrase

- alteration of binding site on topoisomerase IV

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3
Q

Why do fluoroquinolones interfere with DNA synthesis in prokaryotes but not eukaryotes?

A
  • Since prokaryotes are super small, they need their DNA to be supercoiled when not replicating and correctly uncoiled/oriented when needed
  • DNA gyrase is responsible for this and is only found in prokaryotes
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4
Q

What are the adverse effects of fluoroquinolones?

A
  • allergy
  • tendonitis and tendon rupture
  • levofloxacin may cause torsades de point
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5
Q

What is the mechanism of action and use of rifampin?

A
  • inhibits DNA-dependent RNA polymerase and stops the replication of RNA from the daughter DNA strand
  • used for M. tuberculosis and S. aureus
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6
Q

What are the side effects of rifampin?

A
  • drug allergy
  • hepatitis
  • red-orange metabolites
  • induces P450
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7
Q

What is the mechanism of action of metronidazole?

A
  • activated in an anaerobic environment to a toxin for nucleic acids
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8
Q

What are the adverse effects of metronidazole?

A
  • drug allergy
  • metallic taste
  • inhibits aldehyde dehydrogenase - profound vasodilation and tachyarrhythmias
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9
Q

What is the antimicrobial spectrum for metronidazole?

A
  • anaerobic bacteria (H. pylori, C. difficile)

- protozoa (Giardia, Entamoeba, Trichomonas)

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