antibacterial resistance

Question 1

Where is ampC info located?

Answer 1

Chromosomally

Question 2

ampC is resistance to:

Answer 2

beta lactamases:

penicillin and cephalosporin (cannot be inhibited by beta lactamase inhibitors)

Question 3

Which 2 organisms can have ampC?

Answer 3

Enterobacter

Pseudomonas

Question 4

List 3 enterobacteriaceae

Answer 4

Enterobacter
E coli
Klebsiella

Question 5

2 drugs that can induce amp C

Answer 5

cefazolin

ampicilin

Question 6

ESBL is located in?

Answer 6

plasmid

Question 7

amp expression can be _____ or _____

Answer 7

inducible or constitutive

Question 8

ESBL is in which 2 bugs?

Answer 8

E. Coli and Klebsiella

Question 9

b-lactamase inhibitor’s effect onESBL and ampC

Answer 9

Can help with ESBL but cannot help with amp C

Question 10

Who can acquire erm and msr?

Answer 10

Staph Aureus

Strep Pneumo

Question 11

erm is inducible by?

Answer 11

only by macrolides

Question 12

erm affects which two drugs

Answer 12

macrolides (Erythromycin induced) and clindamycin

Question 13

Why are ERM and ampC important

Answer 13

single mutation –> change to consitutive on.

Can occur DURING therapy

Question 14

How does erm work?

Answer 14

dimethylation of 23S rRNA.

Macrolides cannot bind to 23s rRNA (part of 50S)

Question 15

How does msr gene work?

Answer 15

drug efflux

Question 16

what does erm-D-test tell you?

Answer 16

If bug has erm (inducible) or efflux resistence.

Question 17

What can you treat with if bug has msr (efflux resistance) (clindamycin/macrolides)

Answer 17

Clindamycin - yes

Macrolides - no

Question 18

What can you treat with if bug has erm (inducible)?(clindamycin/macrolides)

Answer 18

Do not use clindamycin

Do not use Macrolides

Question 19

Who has narrow spectrum b-lactamase?

Answer 19

S. Aureus (MSSA)
E.coli TEM-1
Klebs Pneumo SHV1

Question 20

narrow spectrum b-lactamse resists which drugs?

Answer 20

penicillin

Ampicillin

Question 21

ESBL (plasmids) resists which drugs?

Answer 21

Penicillins + cephalosporins

Question 22

_____ and ______ both resists penicillin and cephalosporin?

Answer 22

ESBL and ampC

Question 23

MRSA resistance (gene: mecA) due to?

Answer 23

PBP –> PBP2a (low affinity)

Question 24

VRE has two genes ____ and ____ and located in ______

Answer 24

van A, vanB, plasmid

Question 25

How does vancomysin work?

Answer 25

Bind to precursor for cell wall

Question 26

How does VRE have resistance?

Answer 26

Precursor is changed to D-ala-D-lac (from D-ala-D-ala)

Question 27

How does N. Gonorrhoeae have resistance?

Answer 27

altered PBP

Question 28

3 main ways antibiotic resistance

Answer 28

1. inactivate/modify drug
2. Alter drug target
3. reduce ability of drug to get to target

Question 29

E. Coli TEM-1 vs E. Coli

Answer 29

gained penicillimase from plasmid

Question 30

Ecoli’s TEM1 vs Klebsiella SHV1 location difference

Answer 30

Ecoli TEM1 - plasmid

Klebsilla SHV1 - chromosomal

Question 31

Two plasmid that causes resistance of penicillin, cephalosporin, AND carbapenem?

Answer 31

KPC

NDM1

Question 32

Aminoglycosides resistance occurs how?

Answer 32

Inactivating/modifying drug:

N – acetylation, O-nucleotidylation, O-phosphorylation

Question 33

Two ways altered PBP?

Answer 33

mecA (MRSA) - PBP2a
Mosaic PBP (strp pneumoniae/N. gonorrhoeae)

Question 34

VISA (vancomycin - intermediate - susceptibility S. aureus) have two major diff from sensitive strains

Answer 34

1. thicker layer of peptidoglycan

2. Less cross linking (absorbs vanco)

Question 35

_____ of DNA gyrase and ____ of topo IV have quinolone resistance determining region (QRDR)

Answer 35

GyrA & ParC

Question 36

QRDR (quinolone resistance determining region) effect

Answer 36

enzyme less sensitive to inhibition by quinolones –> reduce drug/target affinity