Antibiotic resistance mechanisms

Question 1

What are the ways that bacteria can become resistant to abx?

Answer 1

1. Efflux pumps
2. Reduced uptake
3. Alteration
4. Modify abx
5. Destroy abx
6. Bypassing metabolic pathway
7. Overproduction of target

Question 2

Explain efflux pumps with an example

Answer 2

To actively pump the abx out of the cell
e.g. S.aureus pumps

Mutlidrug efflux pumps (pseudomonas so is very hard to treat)

Question 3

Outline reduced uptake with an example

Answer 3

• Modification of gram -ve outer membrane layer so beta-lactamases cannot get in

Question 4

Outline alteration

Answer 4

Mutations in ribosomal units, altering targets in cell

Question 5

Outline modify abx

Answer 5

via bacterial enzymes

e.g. aminoglycoside phosphatases

Question 6

Outline destroy abx

Answer 6

Beta lactamases= hydrolysis of beta lactam ring making it inactive

Question 7

Outline bypassing metabolic pathway

Answer 7

e.g trimethoprim targets DHFR

Resistant variant of DHFR gene

Question 8

Outline overproduction of target

Answer 8

Producing lots of the target so the abx is used up more quickly but the bacteria still has a lot of the functioning target

Penicillin binding protein is overproduced for example