antibiotics Flashcards
(17 cards)
How is peptidoglycan structured
oligopeptide chains made of L- an D-amino acids that link NAM and NAG heads
what does cross linking link and how
a pentaglycine bridge links L-lysine on one NAM with the D-alanine of another, releasing the second D-alanine in the process
What are beta lactams
antibiotic that disrupts cell wall
e.g. penicillin, vancomycin
how does penicillin work
- Binds irreversibly to DD-transpeptidase (PBP)
- Stops cross linking
- Autolysins degrade wall, usually replaced with more peptidoglycan
- Not with penicillin
- Buildup of peptidoglycan not in cell wall = more autolysins
how does vancomycin work
Binds D-Ala–D-Ala end of stem peptide
stops cross linking
Protein synthesis antibiotics
bind to ribosome - 30S or 50S subunit
include tetracyclines and oxazolidinones (linezolids)
tetracyclines
bacteriostatic
g- and g+
binds to A site of 30S ribosome unit, prevents amino-acyl tRNA binding to A site
Linezolids
bacteriostatic
g+, synthetic, reserve antibiotic
binds to 50S ribosomal subunit
blocks P-site and stops initiation of protein biosynthesis
side effects of tetracycline
black teeth from long term use
side effects of linezolid
bone marrow suppression, peripheral neuropathy from long term use
Quinolones
bactericidal
g+ and g-
active against intracellular pathogens
synthetic
AKA ciprofloxacin
Ciprofloxacin mode of action
prevents DNA unwinding by inhibiting DNA gyrase
Rifamycin’s
bactericidal
g+, primarily used in routine treatment of mycobacteria
Rifamycin’s mode of action
inhibits DNA dependent RNA-synthesis
stops elongation of mRNA by blocking the synthesis of new oligonucleotides
- blocks RNAP binding site
side effects of ciprofloxacin
destroys gut microbiota, increased c.difficile infections
increased risk of tendon rupture
rifampicin side effects
turns secretions red
hepatotoxicity (liver damage)
resistance mechanism: efflux
pumping stuff outside of cell
mechanism for tetracycline
