Antibiotics 3

Question 1

Enterococci bacteria is found everywhere and can cause infection of blood and caus inflammation. true or false?

Answer 1

true

Question 2

where are Enterococci normally found?

Answer 2

Normal flora in the GI and GU tract

Question 3

what is the most prevalent enteroccoci bacteria found in humans?

Answer 3

E. faecium, E. faecalis

Question 4

what types of infections are enteroccoci assoaciated with?

Answer 4

Primarily associated with UTI, wound infections and bacteremia, especially following surgical interventions

Question 5

Enteroccoci is intrinsically less susceptible to b-lactams . TRUE OR FALSE?

Answer 5

TRUE

Question 6

Penicillin G/ampicillin are not bacteriacidal. true ro false?

Answer 6

true

Question 7

Cephalosporin use cannot increase the risk of enterococcal infection. true or false?

Answer 7

false

Question 8

b-lactamases still relatively rare in Enterococci. true or false?

Answer 8

true

Question 9

what is the mechanims of resistance with enterococci?

Answer 9

• Altered peptidoglycan
• PBPs that are not recognised
• decreased aminoglycoside uptake (low level resistance)
• Folate uptake
• Aminoglycosides modifying enzymes (high level resistance)

Question 10

Glycopeptide resistance can be linked to thickened peptidoglycan layer in MRSA (mecA). true or false?

Answer 10

true

Question 11

most VRE are MDR . true or false?

Answer 11

true

Question 12

what does the structure of vancomycin contain?

Answer 12

• Glucose

- N-methyl leucine

Question 13

what member of antibiotic family does vancomycin belong to?

Answer 13

• Glycopeptide

Question 14

how does vancomycin work?

Answer 14

• Binds to the D-Ala-D-Ala in peptidoglycan precursor

- prevents transglycosylation and transpeptidation

Question 15

Resistance to b-lactams does not confer cross-resistance to vancomycin. true or false?

Answer 15

true

Question 16

what type of bateria is vancomycin active against?

Answer 16

• Gram positive

Question 17

vancomycin can cross outer membrane of Gram –ve bacteria. true or false?

Answer 17

false

Question 18

what type of infections does vancomycin used to treta?

Answer 18

• MDR Staphylococci infections

Question 19

how do vancomycin resistant bacteria do gain resistance?

Answer 19

• Mutate the D-Ala-D-Alatermination of the pentapeptide to D-Ala-D-Lac
• Leads to loss of H-bonding

Question 20

E. faecium and E. faecalis containing vanA or vanB gene clusters produce modified peptidoglycan containing D-Ala-D-lactate or D-Ala-D-Ser that does not bind vancomycin. true or false

Answer 20

true

Question 21

VanY Band VanW sit between VanS Band VanH Bin Tn1547. true or false?

Answer 21

true

Question 22

Describe VanA and VanH?

Answer 22

VanA:

• Enzyme homologous to bacterial ligase
• Catalyzes the formation of ester bonds between D-Ala and D-Lac to produce the depsipeptide D-Ala-D-Lac preferentially to the usual dipeptide D-Ala-D-Ala

VanH:

• Dehydrogenase, reduces pyruvate to D-Lac, the substrate for VanA
• Affects cross-linking of precursors to the growing peptidoglycan processed by the PBPs

Question 23

describe VanX?

Answer 23

• D,D-dipeptidase that hydrolyzes D-Ala-D-Ala but can not hydrolyse D-Ala-D-Lac
• Prevents synthesis of precursors ending in D-Ala

Question 24

vanA, vanH, and vanX resistance genes are regulated at the transcriptional level by the VanR-VanS two-component regulatory system. true or false?

Answer 24

true

Question 25

VanZ confers low-level resistance to teicoplanin. true or false?

Answer 25

true

Question 26

Vancomycin is no longer the drug of last resort as resistance becomes widespread, transferred horizontally to other species. TRUE OR FALSE?

Answer 26

TRUE