Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Y3 Medical Micro > L10 Antibiotic sensitivity > Flashcards

L10 Antibiotic sensitivity Flashcards

1
Q

when did antibiotic development start

A

1930s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the problems with AMR development

A

resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what causes AMR

A

AB use in the food industry
AB overuse
AB misuse
resistance spread through the environment - used in animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the development of AMR like

A

resistance increased

new AB decreased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are AB

A

variety of substances derived from microorganisms that control the growth of or kill bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are synthetic AB

A

usually chemically related to natural AB, made to accomplish comparable tasks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are AB for

A

infections

infectious diseases caused by bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what was previously used forAB and where

A

Greece and Serbia - moudly bread to treat wounds and infections
Russia - warm soil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

when was penicillin discovered

A

1928 alexander fleming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

when was penicillin available and by who

A

early WW2 chain and florey developed penicillin

1943

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are the types of AB sensitivity testing

A

clinical
epidemiological
pharmaceutical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the clinical AB sensitivity tests used for

A

confirms organism is sensitive to AB being used to treat patient it suggests alternative AB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the epidemiological AB sensitivity testing used for

A

sensitivity data on common pathogens makes useful public health info, locally and nationally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the pharmaceutical AB sensitivity testing used for

A

Provides info on activity of new ABs against a range of pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the cons of sensitivity tests

A

AB may be successful/fail even if organism lab report sensitive/resistant
sensitivity tests are crude estimates
can’t take into account many crucial aspects of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the clinical relevance of sensitivity tests for microorganisms

A

different phenotype in vivo
growth rate different in vivo
may adhere to devices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the clinical relevance of sensitivity tests for infection location

A 
intra/extracellular
body compartment
pus?
foreign body?
within a biofilm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the clinical relevance of sensitivity tests for host IM response

A

contributes to recovery from infection
influenced by disease
influenced by drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the clinical relevance of sensitivity tests for drug pharamcology

A

pharmacokinetic behaviour
distribution (intra/extracellular)
in vivo metabolism
infection site penetration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

AB sensitivity test methods

A

agar diffusion assays
broth dilution assays
agar incorporation assays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how is an agar diffusion assay done

A

spread plate
place AB discs onto lawn
incubate overnight
examine for inhibition xones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how is the agar diffusion assay measured

A

quantitative - clearing is different depending on AB effect

zone of inhibition is related to minimum inhibitory concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the theory of agar diffusion assay

A

zone of inhibition radius determined by

  • AB diffusion rate
  • bacteria growth rate
  • sensitivity to AB
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is MIC

A

minimum inhibitory concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
why are controls important for agar diffusion assays
zone size can be affected by number of other factors
26
what are the controls for agar diffusion assays
include control organism of known sensitivity | inoculate test organism and control organism on same 'stokes plate'
27
what are the problems with agar diffusion assays
low solubility, ionic charge high molecular weight growth rate of bacteria AB conc in disc
28
what is the problem with low solubility, ionic charge high molecular weight problem in diffusion assays
poor diffusion | small zone of inhibition even if sensitive
29
what is the problem with growth rate of bacteria problem in diffusion assays
slow growing organisms give rise to large zones
30
what is the problem with AB conc in disc problem in diffusion assays
commercially available discs have 67-150% tolerance, 30ug disc could have 2-45ug
31
what is agar diffusion assay II
automated addition of AB disc
32
what is the agar diffusion assay III E test
plastic strip with AB gradient and printed conc incubation AB diffuses out and gradient made E test meniscus - MIC = bacterial growth crosses numbered strip
33
what is a broth dilution assay
grow large bacteria culture, split into several tubes add different conc AB to each tube incubate see growth = MIC, AB required can be spread on plate after to check for bactericidal
34
what is MBC
minimum bactericidal conc
35
what is bacteriostatic
plated from the broth dilution tubes - see when stopped growth in tube but when plated onto agar that conc still grows = didnt kill bacteria
36
what is a control for broth dilution assays
control organism of known sensitivity included in parallel
37
what is an agar incorporation assay
inoculate plate containing AB with test cultures, controls using multipoint indicator
38
what is the benefit pf agar incorporation assays
can test multiple organisms at once
39
what is the agar incorporation breakpoint method
using appropriate series of selected AB (break point) conc MICs can be estimated
40
what factors affect sensitivity tests
slow growing organisms inoculum size must be standardised culture medium composition
41
affect of too much carbohydrate in culture medium
acid pH affects amino glycoside activity
42
affect of thymine in culture medium
interferes with sulphonamide detection
43
affect of divalent cations in culture medium
affect amino glycosides
44
agar diffusion pros
low technology quick set up cheap flexible
45
agar diffusion cons
slow assay
46
what is the affect for slow growing bacteria in sensitivity tests
mtb can take up to 4 weeks to grow
47
how is mtb test sped up
measure production of co2 from labelled substrate | 1-2 weeks
48
what are the pros of broth dilution
accurate MIC | easy automation
49
what are the pros of agar incorporation
20 + strains on one plate | easy to automate
50
what are cons of agar incorporation
AB stability in agar | AB conc critical
51
what is the agar diffusion assay
antibiotic diffuses from an impregnated paper disc into an agar medium on which the test organism is growing
52
what is the broth dilution assay
serial dilutions of the antibiotic in growth medium are inoculated with the test organism
53
what is the agar incorporation assay
antibiotic dilutions are incorporated in an agar medium and spot inoculated with a number of test organisms
54
what is combination therapy indifference
actions of neither drug affected by presence of other
55
what is combination therapy antagonism
one drug prevents full effect of another
56
what is combination therapy synergism
two drugs work better together than sum of their individual activities
57
when should combination therapy be used
treating severe infect when mo single agent sufficient preventing emergence of resistant organisms treating polymicrobial infections e.g. intra abdominal abscesses
58
what may the beneficial interaction of AB in synergy do
potentiate activity of other at biochemical level assist other to penetrate bacterial cell protect from inactivation overcome spontaneous mutation to resistance
59
example of synergy that potentiate activity of other at biochemical level
trimethoprim and sulphonamides target sequential steps in folate synthesis in bacteria
60
example of synergy that assist other to penetrate bacterial cell
penicillin and amino glycoside against enterococci due to increased uptake of latter
61
example of synergy protect from inactivation
beta lactamase enzyme inhibitor protects beta lactam
62
example of synergy spontaneous mutation to resistance
combination therapy of three drugs for TB treatment
63
how can AB antagonism interfere with AB
antagonism of bactericidal activity inducible resistance chemical interactions
64
examples of antagosims of bactericidal activity
bacteriostatic agents inhibit the activity of bactericidal agents like beta-lactams that rely on bacterial growth for killing activity one AB with bateriostatic one with bactericidal = only stops growth doesnt kill - remove AB can recover
65
example of antagonism inducible resistance
chromosomal beta-lactamases by potent inducers like cefoxitin, may cause resistance to poor inducers like cefotaxime
66
example of antagonism chemical interactions
high conc beta lactam ring of some beta lactams can interact chemically with amino groups of amino glycosides = inactivate both
67
alternative to AB sensitivity testing detecting phenotype
detect resistance gene itself | detect the protein product of resistance gene
68
where is the mecA gene
SCCmec element
69
how is SCCmec detected
PCR primer pairs
70
how is MRSA detected
mecA protein product detected - resistance gene in MRSA oxoid PBP2' latex agglutination test if RMSA present =clump

Y3 Medical Micro (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions