ANTIMICROBIALS 1 Flashcards
antibiotics use outside of humans
~3/4 of global antibiotic use is in livestock
use on plants is common but accounts for less amounts
purpose: prevention and treatment of disease and growth promotion
what was the first antibiotic discovered
penicillin
alexander fleming
streptomycin characteristics
a more systematic approach
why are antimicrobials natural products
streptomycin belongs to the larger family of aminoglycosides
antimicrobials bacteriostatic activity
consequence: bacteria stops replicating but doesn’t die per se
antimicrobials bactericidal activity
consequence=cell death
bactericidal vs static activity graph of log of number of bacteria and time
how is antibiotic susceptibility tested
kirby bauer test: each coupon has known concentration of antibiotic
measure the size of the zone of inhibition
dilution susceptibility test: different concentrations of antimicrobials in broth and you look for visible broth
MIC can help you decide the right concentration of antibiotics to use
what are the uses and limitations of antibiotic susceptibility testing (AST)
what are the different possible mechanisms of action of antibiotics
what are the different possible chemical structures of antibiotics?
semi synthetic: derived from natural product and then improved
synthetic is minority of drugs
what are the major antibiotic targets
essential functions and structures
the cell wall is different between bacteria
remember: beta lactams, cell wall synthesis
quinolones: DNA replication
aminoglycosides: protein synthesis
reminder of cell wall structures in gram positive and gram negative
peptidoglycans and cell wall synthesis
PBP: penicillin binding
proteins
the antibiotics will compete with PBP and disrupt the synthesis of pepitodoglycan
how do beta lactams work
penicillin is one
all share the beta lactam ring
several different classes with different activity
beta lactams mimic the 3d structure of the dipeptide D-Ala D-Ala component of peptidoglycans
bactericidal antibiotic
most commonly used class of antibiotics
what are some various cell wall synthesis inhibitors
not being able to affect gram - bacteria is particularly true for glycopeptides and daptomycin
prokaryotic protein synthesis ribosome sizes
major protein synthesis inhibitors
bind pockets of the ribosomes
prevent it from doing what it needs to do
aminoglycosides characteristics
- ribosome releases incomplete peptides
- corrupt the cell with incomplete misfolded proteins
cells die - the membrane starts leaking because its proteins are defected
- almost impossible to administer as pill form, given as an injection
- cannot penetrate cell wall easily without an active transporter, which do not work well without oxygen which is why it does not work against anaerobes
how to choose which antibiotic to use?
what are the bad effects of antibiotics?
