Antibacterial Resistance Flashcards

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1
Q

Bacterial population can rapidly _____ themselves to gain resistance to antibiotics, _______ resistant traits, and ______ them to other bacteria

A

Bacterial population can rapidly modify themselves to gain resistance to antibiotics, propagate resistant traits, and transfer them to other bacteria

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2
Q

define antibacterial resistance

A

ability of bacterium to survive and multiply in presence of an antibiotic

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3
Q

define innate (intrinsic) resistance

A

innate ability of a bacterial species to resist the activity of an antibiotic through its inherent structural or functional characteristics

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4
Q

define acquired (extrinsic) resistance

A

organism obtains the ability to resist the activity of an antibiotic to which it was previously susceptible

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5
Q

why is antibacterial resistance a problem?

A

drug resistance is reversing the progress of antibiotic development

new antibiotic development has rapidly slowed down

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6
Q

How many deaths a year are from antibiotic-resistance infections?

A

23,000 deaths

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7
Q

Where are many of the bacteria that cause antibiotic resistant infections found?

A

in livestock

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8
Q

Are antibiotics used only for therapeutic reasons in animals?

A

used for therapeutic and non-therapeutic

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9
Q

How is antibacterial resistant spread?

A
  1. antibiotic use selects for drug-resistant organisms
  2. resistance not induced by antibiotic itself but by environment created by antibiotics
  3. resistant strains can spread far and wide
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10
Q

How do bacteria disrupt or prevent the action of the antibiotic?

A

-preventing antibiotic from reaching its target
-modifying or bypassing antibiotic target

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11
Q

What are the way bacteria prevent the antibiotic from reaching its target?

A

-reduce ability of antibiotic to enter the cell
-expel the antibiotic out of the cell via efflux pumps
-antibiotic inactivation by modification or degradation

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12
Q

how do bacteria reduce the ability of antibiotic to enter the cell?

A

altering porins in the cell wall

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13
Q

how do bacteria expel the antibiotic out of the cell via efflux pumps?

A

-membrane proteins export or pump out antibiotics
-decreases antibiotic concentration inside the cell

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14
Q

how do bacteria inactivate antibiotics through modification or degredation?

A

enzymes degrade or modify the antibiotic so it is no longer effective

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15
Q

What enzyme do most bacteria possess to degrade antibiotics? which antibiotics is degreaded?

A

B-lactamases
B-lactam antibiotics

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16
Q

what does B-lactamase inhibitors do?

A

-structural analog of B-lactams
-extend activity of B-lactam antibiotic
-inhibit activity of B-lactamase

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17
Q

which of the following will bind first to the B-lactamase - B-lactam antibiotic or B-lactamase inhibitors?

A

B-lactamase inhibitor - has a higher affinity

18
Q

How do bacteria modify the antimicrobial target?

A

bacteria have acquired mutations or modified structures that are no longer recognized by antibiotic

19
Q

How do bacteria bypass the antibiotic target?

A

bacteria acquired a “new” enzyme that allows bypass of a metabolic pathway that the bacteria could be blocking

20
Q

Can we prevent antibacterial resistance from developing?

A

no but we can slow it down by using antibiotics wisley

21
Q

Why can’t we stop antibiotic resistance from developing

A

bacteria naturally develop resistance - it is their constant survival mechanism since they are always competing with other bacteria

22
Q

what are some principles for using antibiotics wisley?

A

-prescribe antibiotics only for bacterial infections
-educate clients on the proper use of antibiotics
-determine the most appropriate antibiotic for the infection

23
Q

How can giving an antibiotic for a viral infection negatively affect the body?

A

affect/kill normal flora > decrease in normal flora > inc susceptibility to other pathogens

24
Q

Why is it important to give antibiotics to animals as directed and not only give 1/2 of the course?

A

stopping halfway through leaves a population that has been under antibiotic pressure and the fittest will the survive and they will proliferate > create antibiotic resistance population

25
Q

How can you determine the most appropriate antibiotic for infection?

A

isolate the bacterial pathogen and performing antibiotic susceptibility testing (AST)

26
Q

what are the 3 antibiotic susceptibility tests we are focusing on in this course?

A

disk diffusion
broth dilution (MIC)
E-tests

27
Q

How are disk diffusions done?

A
  1. make lawn bacterial culture (evenly inoculated)
  2. place filter disks containing antibiotic
  3. incubate
  4. measure ZOI
28
Q

where is the highest concentration of antibiotic with a disk diffusion test?

A

around the disk, decreases as drug diffuses away

29
Q

what is zone of inhibition?

A

diameter around bacterial clearance from disk

30
Q

Is a disk diffusion test quantitative or qualitative?

A

qualitative

31
Q

Which antibiotic would you use?

A

Erythromycin

32
Q

Is a broth dilution test quantitative or qualitative?

A

quantitative

33
Q

How are broth dilution test read?

A

lowest concentration of antibiotic that inhibits bacteria growth is the MIC (minimum inhibitory concentration)

34
Q

What is the tube that is circled in red in a broth dilution test?

A

minimum inhibitory concentration

35
Q

what test is this?

A

broth dilution in a microtiter plate

36
Q

what is MBC?

A

minimum bactericidal concentration

37
Q
A
38
Q

What is an E-test?

A

ease of Kirby-bauer test with ability to determine MIC value

39
Q

what is the MIC?

A

0.25 ug/ml

40
Q

How is the MIC value determined in a E-test?

A

where the elliptical zone of inhibition crosses the E-test

41
Q

How are the plastic strips for E-test filled with antibiotic? (same conc. throughout, gradually inc, gradually dec?)

A

plastic test strips impregnated with gradually decreasing conc. of antibiotic