Antibiotics - Morris

Question 1

How does MRSA acquire resistance?

Answer 1

Acquires SCCmecA
Produces altered PBPs
Beta lactamase inhibitor wont make a difference

Question 2

Piperacillin - and Pip tazo spectrum of activity

Answer 2

Piperacillin = broad gram negative

PipTazo - Broad gram neg and anaerobes

Question 3

Gut anaerobes are known for making

Answer 3

Beta lactamase

Question 4

3rd gen Cephalosporins considered

Answer 4

Extended spectrum Beta lactams

Question 5

Which carbapenem is very resistant to Pseudomonas?

Answer 5

Ertapenem!

Question 6

Greatest value of the cephalosporins?

Answer 6

Effective against ESblactamases

Question 7

Staph aureus resistant first due to

Answer 7

a beta lactamase

Question 8

Mechanism of action of Vanco - (hint) how is it different from the beta lactams

Answer 8

• Binds directly D-ala D-ala
• Skips the PBPs -
• prevents crosslinking

Question 9

Because of the size and shape of vanco what can’t it bind to?

Answer 9

Gram negative cell walls

Question 10

what are some of the toxicities of Vanco?

Answer 10

Renal failure, nephrotoxic

Question 11

VISA - vancomycin intermediately susceptible Staph - mechanism

Answer 11

Thickened cell wall

reduced access of vanco

Question 12

VRSA-

Answer 12

Alteration of the D-ala to D-Lac

preventing binding prevent crosslinking

Question 13

DNA gyrase is a …(type 2 Top)

Answer 13

Topoisomerase 2
- A tetramer
GryA GyrB 2 subunits each
works ahead of the replication fork

Question 14

Topoisomerase 4 made up of (Type 2 top)

Answer 14

ParC and ParE

Works AFTER the replication fork

Question 15

In Gram negatives the FQs target mainly…

Answer 15

DNA gyrase - GyrA especially

Question 16

in Gram positives the FQs target

Answer 16

Topoisomerase 4 - Esp ParC

Question 17

Moderate level of resistance to FQs occurs when

Answer 17

GyrA is mutated in Gram negs

ParC is mutated in Gram pos

Question 18

High level resistance to FQs occurs when

Answer 18

Both enzymes mutated

Question 19

FQ resistance can also be mediated by

Answer 19

• Efflux pumps (on outer cell membrane)

- Gram negatives have porins to reduce accumulation of the drug (also on cell membrane)

Question 20

TMP-SMX are

Answer 20

Bacteriostatic

block folic acid metabolism (S before T)

Question 21

Drugs classified as protein synthesis inhibitors

Answer 21

Macrolides
Aminoglycosides
Tetracyclines
Clindamycin
Oxazolidinones

Question 22

Aminoglycosides notorious for there

Answer 22

Nephro and OTOtoxicity

Question 23

Aminoglycosides - mechanism of action

Answer 23

Bind 30S ribosome
AND
CIDAL - make cell leaky by binding Mg and Ca
They also have a post-antibiotic effect

Question 24

Which bacteria are most resistant to aminoglycosides?

Answer 24

Gram positives - thick cell wall hard to penetrate

Question 25

Mechanisms of resistance to aminoglycosides?

Answer 25

Efflux, reduce entry

Modify the 30S ribosome prevent binding

Question 26

Mechanism of action of Clindamycin and Macrolides?

Answer 26

Bind 50S ribosome - are bacteriostatic

Question 27

Unique feature of Clindamycin

Answer 27

Has anaerobic activity

Question 28

Mechanisms of resistance to Clindamycin and Macrolides?

Answer 28

Modify the subunit

Question 29

Side Effects of Clindamycin and Macrolides

Answer 29

GI intolerance

Question 30

Tetracyclines - mechanism of action

Answer 30

Bind 30S subunit

Question 31

Linezolid is a

Answer 31

Oxazolidinone -

Binds 50S

Question 32

Spectrum of activity of Linezolid?

Answer 32

Gram positives includes MRSA and VRE

NOT gram negatives

Question 33

Side effects of Linezolid?

Answer 33

Neutropenia, Neuropathy

Question 34

Metronidazole MOA

Answer 34

Produces toxic radicals
Bacteriacidal
ONLY against Anerobes -