Antibiotic Resistance Mechanisms Flashcards
1
Q
6 targets of antibiotics
A
- cell wall synthesis
- DNa replication
- RNA synthesis
- proteins synthesis
- folic acid synthesis
- membrane disruption
2
Q
example and mechanism behidn disrupting the cell wall
A
- beta lactams (penicillin)
- during cell wall growth, an enzyme called transeptidase facilitates the linking of two peptide side chains off of M of the peptidoglycan cell wall
- it does this by removing one D-Ala and linking the next one in the chain to an adjacent L-Lys
- beta lactam’s backbone mimics that of D-Ala, D-ALa but the transpeptidase enzyme does not recognize it
3
Q
blocking DNA replication
A
- fluoroquinilones
- block DNA gyrase and topoisomerase
- this disrupts DNa synthesis
4
Q
blocking RNa synthesis
A
-rifampicin
-
5
Q
blocking protein synthesis
A
- tetracylcines, macrolides
- tetracyline block the binding of amino acyl tRNA
- macrolides block the extension of the nascent polypeptide by blocking the A site
6
Q
folic acid synthesis (blocking the synthesis of DNA subunits)
A
-sulfonamides
7
Q
membrane disruption
A
- daptomycin for gam +
- colistin for gram -
- daptomycin forms a pore in the membrane
- colistin binds to LPS and disrupts the membrane
8
Q
urgetn threats
A
- C diff
- neisseria gonorrhea
- carbapenam resistant enterobacteriaceae
9
Q
how do bacteria resist the action of antibiotics?
-5 methods
A
- inactivating the antibiotic
- modifying or replacing the target
- remove the antibiotic from the cell via eflux pumps
- prevent uptake of the antibiotic
- develop persister populations: cells neither grow nor die during antibiotic exposure
10
Q
inactivating the antibiotic
A
- beta lactam is an ex
- a protease cleaves the beta lactam ring
- secreted from the cytoplasm
- the gene for protease is often encoded on a plasmid DNA
11
Q
modifying or replacing the target
A
- vancomycin resistance
- vancomycin blocks cell wall sythesis by binding the D ala D ala and blocks transpeptidase
- the bacterial cell with resistance will replace the first D ala with a D lactate, inhibiting the vancomycin from binding
12
Q
removing the anitbiotic from the cell
A
- done via eflux pumps
- this causes multi drug resistnace
- AcrAB efflux pump uses a proton gradient to pump out the antibiotics, energy dependent
13
Q
preventing antibiotic uptake
A
- decrease outer mem porin gene production in gram neg (regulation of OprD in p. aeruginosa)
- increased thickness/synth of the peptidoglycan cell wall gram pos
- capsule formation
- biofilm production
14
Q
OprD
A
- gene that forms a pore in the gram neg membranes allowing for small nutrients including amino acids
- major route for carbapenem influx into the periplasm
- in drug resistant strains there is a negative regulator of the RNA polymerase for this gene
15
Q
develop persister populations
A
- cells neither grow nor die during antibiotic exposure
- this happens when the full course of antibiotics is not taken
