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Tony's lectures > Antibiotics 3 > Flashcards

Antibiotics 3 Flashcards

1
Q

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

A

true

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2
Q

where are Enterococci normally found?

A

Normal flora in the GI and GU tract

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3
Q

what is the most prevalent enteroccoci bacteria found in humans?

A

E. faecium, E. faecalis

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4
Q

what types of infections are enteroccoci assoaciated with?

A

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

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5
Q

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

A

TRUE

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6
Q

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

A

true

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7
Q

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

A

false

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8
Q

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

A

true

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9
Q

what is the mechanims of resistance with enterococci?

A
  • Altered peptidoglycan
  • PBPs that are not recognised
  • decreased aminoglycoside uptake (low level resistance)
  • Folate uptake
  • Aminoglycosides modifying enzymes (high level resistance)
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10
Q

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

A

true

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11
Q

most VRE are MDR . true or false?

A

true

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12
Q

what does the structure of vancomycin contain?

A
  • Glucose

- N-methyl leucine

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13
Q

what member of antibiotic family does vancomycin belong to?

A
  • Glycopeptide
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14
Q

how does vancomycin work?

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

- prevents transglycosylation and transpeptidation

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15
Q

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

A

true

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16
Q

what type of bateria is vancomycin active against?

A
  • Gram positive
17
Q

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

A

false

18
Q

what type of infections does vancomycin used to treta?

A
  • MDR Staphylococci infections
19
Q

how do vancomycin resistant bacteria do gain resistance?

A
  • Mutate the D-Ala-D-Alatermination of the pentapeptide to D-Ala-D-Lac
  • Leads to loss of H-bonding
20
Q

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

A

true

21
Q

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

A

true

22
Q

Describe VanA and VanH?

A

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
23
Q

describe VanX?

A
  • 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
24
Q

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

A

true

25
Q

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

A

true

26
Q

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

A

TRUE

Tony's lectures (8 decks)

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