micro poop 3.

Question 1

What are the newest antibiotics targeting?

Answer 1

plasma membrane - bacteria have a step in plasma membrane making that we don’t

Question 2

Why is there so much antibiotic resistance?

Answer 2

use on farm animals before they’re even exposed

Question 3

natural (intrinsic) resistance

Answer 3

chromosomally mediated and is predictable

Question 4

mutational resistance

Answer 4

random mutation - secondary resistance occurring after therapy with the antimicrobial has begun

Question 5

transferable resistance

Answer 5

plasmid-mediated through conjugation (mating), transaction (bacteriophge transmission), transformation (uptake of DNA from environment)

Question 6

What are the two transposable genetic elements?

Answer 6

transposons and insertion sequences —> “jumping genes”

Question 7

What is the essential element to the transposition process?

Answer 7

that both elements are flanked on either end by short identical sequences of DNA in reverse order (inverted repeats)

Question 8

What is required for transposons and insertion sequences to work?

Answer 8

existence on a replicon (chromosome, bacteriophage, plasmid) because they are incapable of autonomous self-replication

Question 9

insertion sequences

Answer 9

mobile genetic elements that are known to encode only functions involved in insertion events (ability to turn on/off because they don’t want to waste energy on things they don’t need)

Question 10

What does Staphylococci have to give it resistance?

Answer 10

insertion sequence

Question 11

transposon

Answer 11

central sequence containing the phenotypic marker gene and transposase genes (have other gene material outside of what an insertional sequence has)

Question 12

integron

Answer 12

DNA elements with the ability to capture genes by site-specific recombination - provides a convenient insertion site for antibiotic-resistance genes from foreign DNA sources

Question 13

What is the difference between an integral and a transposon?

Answer 13

transposon is mobile, integrons (nonmotile) can be within transposon

Question 14

gene cassettes

Answer 14

discrete genetic elements that may exist as free, circular, non-replicating DNA molecules when moving from one genetic site to another - include a gene and an integrase-specific recombinationn site

Question 15

How can cassettes be added/deleted/moved?

Answer 15

due to the attC site

Question 16

What are the 7 mechanisms of antibiotic resistance?

Answer 16

enzymatic inactivation, decreased permeability, efflux (kick antibiotic out), alteration of target site, protection of target site, overproduction of target, bypass of inhibited process

Question 17

How do organisms resist b-lactam antibiotics?

Answer 17

with beta-lactamases (bacterial enzyme) that inactivate beta-lactam antibiotics by hydrolysis of the beta-lactamase bond

Question 18

How does beta lactamase work?

Answer 18

require a serine or zinc atom moiety at the active site to hydrolyze the beta-lactam ring

Question 19

How are beta lactams being modified to avoid resistance?

Answer 19

created beta-lactamase inhibitors and inhibitor combinations (bind irreversibly to beta-lactamases)

Question 20

What is special about the extended spectrum cephalosporins and carbapenams?

Answer 20

they are resistant to beta-lactamases

Question 21

What drug is most effective against ESBL-producing enterobacteriaceae?

Answer 21

carbapenems (any drug that ends in penem)

Question 22

What common organisms primarily have extended-spectrum beta-lactamases?

Answer 22

klebsiella, e coli, proteus

Question 23

What are AmpC Beta-lactamases?

Answer 23

differ from ESBLs because they are resistant to available beta-lactamase inhibitors and can hydrolyze the cephamycins - usually produced at low levels by organisms - resistance when produced at high levels (only carbapenems and 4th generation cephalosporins still effective)

Question 24

What are super bugs?

Answer 24

carbapenem-hydrolyzing enzymes - most diverse group of all beta-lactamases - resistant to inhibition by beta-lactam inhibitors (plasmid encoded)

Question 25

NDM-1 producing enterobacteriaceae

Answer 25

no antibiotics that touch it - carbapenase

Question 26

How does staphylococci resist beta-lactams?

Answer 26

production of beta-lactamases and production of modified transpeptidase targets that are impervious to antibiotic activity (such as MRSA)

Question 27

What type of microorganism is now resistant to penicillin? What has been our response?

Answer 27

pneumococci and enterococcus - we no longer use antibiotics for simple things like ear infection unless it is a repeated one

Question 28

IS431

Answer 28

integron that can trap and cluster resistant genes for other antibiotics (found on the MecA gene plasmid - how MRSA is resistant)

Question 29

How is S. Aureus methicillin resistant?

Answer 29

expression of the mecA gene which encodes PBP2a - protein with low affinity for beta lactam antibiotics

Question 30

PBPs

Answer 30

transpepdidases in the cytoplasmic membrane - catalyze the synthesis of the peptidoglycan that forms the cell wall - alterations to this can lead to beta-lactam antibiotic resistance (such as PBP2A on the mega gene)

Question 31

How does vancomycin work?

Answer 31

blocks cell wall synthesis by binding to the C-terminal D-Ala-D-Ala residue

Question 32

How are strains becoming resistant to vancomycin?

Answer 32

adaptive multifactorial response to sublethal vancomycin exposure - thicker cell walls trap vancomycin, blocking action

Question 33

How does acquired resistance to ahminoglycosides happen?

Answer 33

combination of decreased drug uptake, efflux pump activity, enzymatic modification of the drug

Question 34

How does resistance to tetracycline happen?

Answer 34

efflux pump and ribosomal protection (sometimes both)

Question 35

How does resistance to macrolides happen?

Answer 35

alteration of target site (ribosome) and efflux

Question 36

How does resistance to sulfonamides happen?

Answer 36

mutational (alteration of metabolic pathway or target site)

Question 37

How does resistance to trimethoprim happen?

Answer 37

changes in cell permeability and altered metabolic pathway

Question 38

How does resistance to fluoroquinolone happen?

Answer 38

alteration of target enzymes (esp DNA gyros and topoisomerase)