Antibiotic Resistance Mechanisms

Question 1

What drug class does penicillin belong to?

Answer 1

Beta lactams.

Question 2

How do beta lactams work?

Answer 2

They mimic the peptidoglycan D-ala D-ala so that transpeptidase binds to penicillin instead of to the nascent cell wall.

Question 3

What is the antibiotic mechanism of fluoroquinolones?

Answer 3

Prevent DNA replication by inhibiting DNA gyrase and topoisomerase.

Question 4

What is the antibiotic mechanism of rifampicin?

Answer 4

Inhibit RNA synthesis by binding to the beta subunit of RNA polymerase.

Question 5

What is the antibiotic mechanism of tetracyclines?

Answer 5

Inhibit protein synthesis by binding to ribosomes.

Question 6

What do sulfonamides do?

Answer 6

Inhibit folic acid synthesis.

Question 7

What does daptomycin do? What bacterial cell types does it work on?

Answer 7

Causes pore formation and K+ efflux (depolarization) of gram positive bacteria.

Question 8

What does colistin do? What bacterial cell types does it work on?

Answer 8

Colistins destroy the outer and inner membranes of gram negative bacteria

Question 9

Name the five antibiotic resistance mechanisms.

Answer 9

1. Antibiotic inactivation
2. Modify or replace the target
3. Remove the antibiotic from the cell
4. Prevent drug uptake
5. Develop persister populations

Question 10

What is the mechanism by which bacteria resist treatment by beta lactams?

Answer 10

The bacteria encode a beta lactamase which cleaves the lactam ring of drugs.

Question 11

Are beta lactamase genes often found on plasmids? What is the consequence of this?

Answer 11

Yes, they are therefore transferrable.

Question 12

What is the mechanism by which bacteria resist treatment by vancomycins?

Answer 12

Bacteria change the D-ala D-ala to D-lactate D-ala so that vancomycins can’t bind, but transpeptidase can still bind to catalyze cross-linking

Question 13

Name an efflux pump that can pump out antibiotics.

Answer 13

AcrAB efflux pump.

Question 14

What is OprD?

Answer 14

A gene in pseudomonas aeruginosa that is repressed so that pores are less frequent in the outer membrane to prevent uptake of antibiotic drugs.

Question 15

What are four mechanisms of antibiotic uptake prevention?

Answer 15

1. Decrease outer membrane porin gene transcription and translation.
2. Increase thickness of peptidoglycan wall.
3. Capsule formation.
4. Biofilm formation.

Question 16

How are TB resistant to rifampicin?

Answer 16

Mutated beta subunit on RNA polymerase - rifampicin can’t bind.

Question 17

What are three methods of acquiring resistance via horizontal gene transfer?

Answer 17

1. Transformation (plasmids)
2. Conjugation (pili)
3. Transduction (phage)