Pharmacology - Macrolides and Quinolones Flashcards
Why are macrolides effective for pulmonary infections?
Excellent lung tissue penetration
What disease are macrolides effective against?
Legionnaires disease (have intracellular activity against Legionella)
What ribosome subunit do macrolides act on?
What effect does this have?
23s rRNA of the 50s subunit
Blocks translocation of protein synthesis
What is the major cause of macrolide resistance in Gram-positive organisms?
How does this happen?
Methylase - modifies the 23s RNA target causing decreased drug binding
What type of drug is erythromycin?
Macrolide
What is the biggest reason for discontinuing erythromycin?
How does this side effect occur?
GI intolerance
Directly stimulates gut motility - nausea, vomiting, diarrhea, anorexia
How do quinolones kill bacteria?
Act by inhibiting one or both of the 2 types of type II topoisomerases which include DNA gyrase (topoisomerase II) and topoisomerase IV
What is the specific target of quinolones?
Topoisomerase II (DNA gyrase) in Gram (-) Topoisomerase IV in Gram (+)
What three categories of infections do fluoroquinolones treat?
Urogenital
Respiratory
GI
What kind of bacteria do fluoroquinolones target?
Gram (-) bacteria
What are the three most common sources of resistance to quinolones?
Mutations in type II topoisomerase genes
Alteration in the expression of membrane porins
Alteration in the expression of efflux pumps
Why are quinolones selectively toxic?
Differences between bacterial and eukaryotic forms of the enzymes
