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5) Food Microbiology > 19) Antibiotics in the Food Supply > Flashcards

19) Antibiotics in the Food Supply Flashcards

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1
Q

what is AMR?

A

antimicrobial resistance

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2
Q

antimicrobials are used for what?

A

human medicine
agricultural production
food processing

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3
Q

since AMR is increasing globally, what are consumers concerned about?

A

increased difficulty in threatening infections due to AMR bacteria

this is b/c they don’t understand the true threat of AMR bacteria

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4
Q

what is ARG and ARB?

A

antibiotic resistance genes

antibiotic resistanc bacteria

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5
Q

how can ARG and ARB be detected?

A

by using antibiotics in food producing animals

  1. manure is spread in soil/crops
  2. manure ARGs and ARBs mix with environmental ARGs and ARBs
  3. if gene is selected, they will become more antimicrobial resistant
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6
Q

what is an example of how you may consume ARBs and ARGs?

A

by eating raw veg

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7
Q

define AMR

A

Antimicrobial resistance: deceased susceptibility of a multitude of microbes to a broad spectrum of single or multiple antibiotics

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8
Q

what are 2 categories of antibiotics?

A

bactericidal

bacteriostatic

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9
Q

a) what are key properties of bactericidal antimicrobials?

b) what are key properties of bacteriostatic antimicrobials

A

bactericidal

  1. kills the bacterial cell
  2. target key structures (biosynthesis of cell wall or DNA)

bacteriostatic

  1. inhibits further growth
  2. targets protein synthesis
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10
Q

what are uses of antimicrobials in food production?

A
  • treat infected animals, prevent infection of animals, promote growth
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11
Q

a) how is AMR due to genetic changes transmitted?

b) how are mutated and acquired AR genes transmitted?

A

a) vertical or horizontal gene transmission

b) vertical transmission

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12
Q

differentiate vertical and horizontal gene transmission

A

horizontal: movement of genetic material between organisms
vertical: DNA from parent to offspring

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13
Q

antibiotics selects for who?

A

resistant individuals

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14
Q

what does HGT stand for? what is it?

A

horizontal gene transfer

HGT mediates the transfer of AMR to bacterial cells by mobile genetic elements (plasmids, transposons, integrons), which can occur via conjugation, transformation and transduction

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15
Q

which process is faster? HGT or VGT?

A

vertical is slower b/c it takes time for mutations to accumulate and cells to divide

horizontal is fast and can play a big role in spreading AMR in entire ecosystems

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16
Q

what are 5 main mechanisms of AMR?

A
  1. export
  2. destruction
  3. modification
  4. altered receptors
  5. membrane composition
17
Q

what is colistin?

A
  • old antibiotic
  • not used in humans due to kidney toxicity, until the spread of AMR in 90’s when it’s use increased
  • now it is a last-resort/emergency antibiotic for multidrug-resistant MOs
18
Q

what is the significance of finding mobilized colistin resistance (MCR) gene?

A
  • it confers plasmid mediated resistance to colistin

- shows that MCR is capable of HGT b/w species

19
Q

what are 3 main methods of detecting AMR?

A
  1. disk diffusion method
  2. MIC test strips
  3. sensititre MIC plate
20
Q

describe the disk diffusion method (aka agar diffusion or kirby-bauer test)

what is it?

what is the process of using them?

A

tests sensitivity of a bacteria to a specific antibiotic (a method of detecting AMR)

process:
1. uses antibiotic discs placed on agar plates containing a lawn of bacteria. Then plate is incubated
2. if an antibiotic stops bacterial growth, this is the zone of inhibition
3. measure zone diameter and compare to database of zone standards, which tells you if bacterium is susceptible, moderately susceptible or resistant

21
Q

in the disk diffusion method, what does the size of zone depend on?

A
  1. how effective the antibiotic is at stopping growth of the bacterium
  2. rate diffusion of the antibiotic within the agar medium
22
Q

describe MIC test strips

what are they?

what is the process of using them?

A
  • minimal inhibitory concentration: lowest concentration of a drug at which no visible growth occurs
  • method of detecting AMR

process:

  • MIC test strips have a predefined antibiotic conc gradient
  • test strips are incubated on bacteria on a an agar plate
  • ellipse shaped growth inhibition areas form on the agar plate
  • MIC can be determined from concentration markings of where the growth meets the strip
23
Q

describe sensititre MIC plates for detecting AMR

A
  • 96 well plates which contain lyophilized antibiotics
  • used to determine the MIC to a variety of antibiotics

process

  • bacteria are inoculated into each well of the plate
  • plates can be inspected visually to determine MIC for each antibiotic
24
Q

how can AMR be detected with genetic methods?

A

from the whole genome sequence

5) Food Microbiology (21 decks)

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