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
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
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
4
Q
What are the adverse effects of fluoroquinolones?
A
- allergy
- tendonitis and tendon rupture
- levofloxacin may cause torsades de point
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
6
Q
What are the side effects of rifampin?
A
- drug allergy
- hepatitis
- red-orange metabolites
- induces P450
7
Q
What is the mechanism of action of metronidazole?
A
- activated in an anaerobic environment to a toxin for nucleic acids
8
Q
What are the adverse effects of metronidazole?
A
- drug allergy
- metallic taste
- inhibits aldehyde dehydrogenase - profound vasodilation and tachyarrhythmias
9
Q
What is the antimicrobial spectrum for metronidazole?
A
- anaerobic bacteria (H. pylori, C. difficile)
- protozoa (Giardia, Entamoeba, Trichomonas)