Week 14.2 Antibiotic Resistance

Question 1

Affect of mutations on antibiotic resistance

Answer 1

Antibiotic resistance can result from mutations in genes that are associated w/ the antibiotic mechanism
Ex: a mutation to the binding site of rifampicin creates resistance to rifampicin

Question 2

Why do bacteria sometimes lose resistance genes if the antibiotic disappears?

Answer 2

Expressing and replicating antibiotic resistance genes cost energy and resources

Question 3

4 common mechanisms of antibiotic resistance

Answer 3

1. Antibiotic Modification
2. Antibiotic Target Modification
3. Reduced Permeability
4. Efflux Pumps

Question 4

Antibiotic Modification

Answer 4

Destruction or modification of an antibiotic removes its activity
-Ex: beta-lactamases are enzymes that cleave the beta-lactam ring of penicillin, so destroying the beta-lactam ring inhibits its ability to bind to PBPs

Question 5

Antibiotic Target Modification

Answer 5

Mutations in penicillin binding proteins can decrease the binding affinity of penicillin by changing associated amino acids
-these mutations decrease the effectiveness of penicillin

Question 6

Minimum inhibitory concentration (MIC)

Answer 6

lowest concentration of antibiotic that inhibits visible growth of bacteria

Question 7

Reduced Permeability

Answer 7

Mutations can change the structure of a porin and prevent antibiotics from reaching their target
-porins: protein pores in the outer membrane of gram (-) cells

Question 8

Efflux pumps

Answer 8

Move antibiotics out of a cell
-substrate-specific or broad activity

Question 9

Would reduced permeability or efflux pumps be more effective against penicillin?

Answer 9

Efflux pumps because its overexpression can decrease the concentration of penicillin in the periplasmic space