Mechanisms of Antimicrobial Resistance

Question 1

Intrinsic Antibiotic Resistance

Answer 1

Resistance that happens as a natural property of the bacteria

Question 2

Acquired Resistance

Answer 2

Genetic mutation or acquisition of new genes

Question 3

Three Broad catagories of atbx resistance

Answer 3

Inactivate/modify drug
Alter the atbx target
Reduce the ability of drug to get to the target

Question 4

Porins

Answer 4

Found in Gram (-) bacteria in their outer membrane, forming hydrophillic channels to taken in nutrients. Atbx can get in this way

Question 5

Efflux Pumps

Answer 5

Structures in bacerial ccell membrane aimed to remove substrates from the cytoplasm

Gram - and +

Question 6

B-lactams inhibit cell wall synthesis by

Answer 6

Binding to penicillin binding proteins that are responsible for peptide crosslinking in the peptidoglycan wall

Question 7

B-Lactam resistance

Answer 7

Altering the drug: B-lactamase

Mod the target: altered PBPs

Question 8

Narrow Spectrum B-lactamases

Bugs

Answer 8

Staphylococci, E. coli, H influenzae, klebsiella penumoniae

Question 9

Narrow Spectrum B-lactamases

Answer 9

Only targets penicillin drugs

Found in both grams

Question 10

ESBLs

Bugs

Answer 10

Just gram (-) rods
E. coli
Klebsiella pneumoniae

Question 11

ESBLs

Answer 11

Can also target cephalosporins\

Plasmids usually

Question 12

ampCs

Bugs

Answer 12

Enterobacter, pseudonomas

Question 13

ampCs

Answer 13

Targets penicillins and 1-3 gen cephalosporins

Question 14

Carbapenemases

Answer 14

Plasmid mediated

Mostly klebsiella, but can transfer to e. coli

Question 15

KPC

Answer 15

Klebsella pneumoniae carbapenemases

Plasmid mediated

Question 16

NDM-1

Answer 16

produced by klebsiella, hydrolzes all b-lactams

Plasmid mediated

Question 17

Describe the regulation of ampC expression

Answer 17

Chromosomal, can be induced or constitutive

Some B-lactams can induce the production of ampC (ampicillin and cefazolin (ceph gen 1))

Question 18

mecA

Answer 18

Altered PBP found in staphylococci

Encodes PBP2

Found in MRSA

Question 19

Mosaic PBP

Answer 19

Found in S. pneumoniae and N. gonorrhoaea

Mosaid DNA strands coding for PBPs

Question 20

Vancomycin

MoA

Answer 20

Binds to terminal D-ala-D-ala portion of the peptide chain precursor

Question 21

Vancomycin

Resistance-modifying the target

Answer 21

Elmost exclusively enterococcus spp

Replaces the last alanine with a lactate, reducing binding affinity

Plasmia mediated

Question 22

Vanco

Resistance- preventing drug-target interaction

Answer 22

S. aureus

Binding free vanco in the existing cell wall

Question 23

VISA

Answer 23

Vancomycin intermediate susceptibility S. aureus

Thicker walls, with less cross linkingg

Question 24

Quinolones

MoA

Answer 24

Target DNA gyrase and DNA topoisomerase

Question 25

In gram negative bacteria, _____ is the more susceptible target of quinolones

Answer 25

DNA Gyrase

Question 26

In gram positive bacteria, _____ is the more susceptible target of quinolones

Answer 26

Topoisomerase IV

Question 27

Cipro targets

Answer 27

Gram negative and DNA gyrase

Question 28

Levofloxacin targets

Answer 28

Both, but Topoisomerase IV better

Question 29

Quinolone resistance

modding the target

Answer 29

DNA substitutions in both cell targets, called the quinolone-resistance-determining region (QRDR)

Question 30

Macrolides

MoA

Answer 30

Binding to 50s subunit of ribosome

Question 31

Macrolide Resistance

Modding the target

Answer 31

Methylating the ribosome, which also resists clindamycin

Constitutive or inducible (not ind to clinda though)

Question 32

Macrolide Resistance

Efflux pumps

Answer 32

Resistant to macros, sensitive to clinda

Question 33

Aminoglycoside Resistance

Modding the drug

Answer 33

N-acetylation
O-nucleotidylation
O-phosphorylation

Of the drug

Found on chromosome