U2.1.2 Experiment 8-9 Flashcards

1
Q

T/F Once agent has been identified & deemed as clinically significant, proper selection of antimicrobial agents is performed.

A

T

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2
Q

Provide MIC (minimum inhibitory concentration) values or zones of inhibition established using cut-off points/break off

A

Kirby-Bauer Disk Method

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3
Q

AST : Kirby-Bauer Disk Method

Spreading of bacteria on an agar plate and placing paper discs impregnated with antibiotics on the plate

A

Disk Diffusion

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4
Q

AST : Kirby-Bauer Disk Method

Area around antibiotic disk where no bacterial growth can be seen

A

Zone of Inhibition

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5
Q

AST : Kirby-Bauer Disk Method

What does the zones indicate

A

antibiotic is successful in stopping bacterial growth or killing bacteria

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6
Q

AST : Kirby-Bauer Disk Method

Diameter is measured to

A

compare efficacy of antibiotics and monitor antimicrobial resistance

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7
Q

AST : Kirby-Bauer Disk Method

Specimen

A

< 24 hour-old test culture on BAP, TSA or NAP

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8
Q

AST : Kirby-Bauer Disk Method

Turbidity of suspension of Inoculum is compared to

A

0.5 McFarland standard

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9
Q

AST : Kirby-Bauer Disk Method

Desired Turbidity of Inoculum

A

same turbidity with McFarland Standard

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10
Q

AST : Kirby-Bauer Disk Method

Turbidity of Inoculum is adjusted by

A

Adjust by adding sufficient sterile saline or adding more colonies

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11
Q

AST : Kirby-Bauer Disk Method

Inoculation of MHA Plate
Manner of streaking

A

inoculated by overlap method of streaking

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12
Q

AST : Kirby-Bauer Disk Method

Inoculation of MHA Plate
Rotate plate ____ each time for even distribution

A

60°

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13
Q

AST : Kirby-Bauer Disk Method

Inoculation of MHA Plate
Number of times plate is rotated

A

3-4x to ensure that it’s confluent

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14
Q

AST : Kirby-Bauer Disk Method

Inoculation of MHA Plate
Incoulation is done [time] from time of standard inoculum was prepared

A

done <15 minutes from time of
standard inoculum was prepared

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15
Q

AST : Kirby-Bauer Disk Method

Application of Antibiotic Disks
At least ____ from each other
At least ____ from edge of the plate

A

At least 24mm from each other
At least 10mm from edge of the plate

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16
Q

AST : Kirby-Bauer Disk Method

inverted and placed in incubator set at ___ for ____ hrs

A

set at 35- 37C for 16-18 hours

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17
Q

AST

uses standardized amount of test inoculum present in Mueller Hinton Broth (MHB) and a selected antimicrobial agent

A

Broth Dilution

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18
Q

AST : Broth Macrodilution

Medium used

A

Mueller Hinton Broth (MHB)

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19
Q

AST : Broth Macrodilution

Antimicrobial agent is diluted _____ fold

A

two fold

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20
Q

AST : Broth Macrodilution

lowest concentration of antimicrobial agent that completely inhibits visible growth

A

MIC

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21
Q

AST : Broth Macrodilution

Interpretative categories

A

Susceptible (S)
Intermediate (I)
Resistant (R)

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22
Q

Two categories of Broth Macrodilution

A

Broth microdilution & Broth macrodilution

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23
Q

Two categories of Broth Macrodilution

Main difference

A

volume of the MHB used

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24
Q

AST : Broth Macrodilution

Specimen used

A

Culture on BAP

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25
Q

AST : Broth Macrodilution

Adjusted inoculum diluted _____

A

diluted 1:200

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26
Q

AST : Broth Macrodilution

Final bacterial concentration

A

5x10^5 CFU/mL

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27
Q

AST : Broth Macrodilution

Test 1-10 is used for

A

actual test

28
Q

AST : Broth Macrodilution

Test 11 is used for

A

Inoculum Control (IC)

29
Q

AST : Broth Macrodilution

Test 12 is used for

A

Broth Control (BC)

30
Q

AST : Broth Macrodilution

Test 13 is used for

A

Antibiotic Control (AC)

31
Q

AST : Broth Macrodilution

Incubate ____ C for _____ hrs

A

Incubate 35-37°C for 18-24 hrs

32
Q

AST : Broth Macrodilution

Growth on Control Tube 11

A

Visible Growth

33
Q

AST : Broth Macrodilution

Growth on Control Tube 12

A

No Visible Growth

34
Q

AST : Broth Macrodilution

Growth on Control Tube 13

A

No Visible Growth

35
Q

AST : Broth Macrodilution

used to determine tube with lowest antibiotic concentration with no visible growth

A

MIC

36
Q

AST : Broth Macrodilution

T/F 0.01 mL from each tube that have no visible growth shall be pipetted on agar plates

A

T

37
Q

AST : Broth Macrodilution

lowest antibiotic concentration that results in 99% killing

A

MBC

38
Q

AST : Broth Macrodilution

Determined by identifying the plate with lowest antibiotic concentration showing no visible growth

A

MBC

39
Q

Test for Antimicrobial Resistance

Detected in Gr (+) & Gr (-) Bacterias

A

Beta Lactamase

40
Q

due to different external and internal factors that prevent the action of antimicrobials

A

Antibiotic Resistance

41
Q

Test for Beta Lactamase

cleaves beta lactam ring of penicillin and cephalosporins

A

Beta lactamase enzyme

42
Q

Test for Beta Lactamase

bacterias detected

A

Staphylococcus, H. Influenzae, N. gonorrhoeae

43
Q

Test for Beta Lactamase

methods to detect antibiotic resistance (3)

A

Iodometric, Acidimetric, Chromogenic

44
Q

Test for Beta Lactamase

most sensitive method

A

Chromogenic; Cefinase Test

45
Q

Cefinase Test

Positive result

A

Color change from yellow to red

46
Q

Cefinase Test

species that take up to 1 hr to develop color change

A

Staphylococcus

47
Q

Test for Beta Lactamase

Specimen

A

Culture of Staphylococcus growing in BAP or TSA

48
Q

Test for Antimicrobial Resistance

used to determine MRSA

A

Cefoxitin Screen Test

49
Q

Test for Antimicrobial Resistance

Excellent induced or mecA gene

A

Cefoxitin

50
Q

Cefoxitin

code for PBP2a responsible for
methicillin and oxacillin resistance

A

mecA gene

51
Q

Cefoxitin Screen Test

Specimen

A

Culture of Staphylococcus aureus in BAP or TSA

52
Q

Cefoxitin Screen Test

___ ug of cefoxitin disk used

A

30ug

53
Q

Cefoxitin Screen Test

Incubate plates at _____

A

Incubate plate at 30-35°C. Do not incubate above 35°C.

54
Q

Cefoxitin Screen Test

Measure zone of inhibition S.aureus
≥ 22 mm

A

Susceptible; Negative

55
Q

Cefoxitin Screen Test

Measure zone of inhibition S.aureus
≤ 21 mm

A

Resistant; Positive

56
Q

Used for AST and part of Gradient Diffusion Test

A

E-TEST

57
Q

AST

uses plastic strip

A

E-Test

58
Q

AST

Quantitative assay for determining MIC

A

E-Test

59
Q

AST E-Test

applied onto an inoculated agar surface

A

Test Strip

60
Q

AST E-Test

After 18 hours ____ is formed around the strip

A

symmetrical inhibition ellipse

61
Q

AST E-Test

MIC is read by

A

Observe where the relevant inhibition ellipse intersects the strip and read the MIC at complete inhibition

62
Q

AST E-Test

Set up time :
Time to Result :

A

Set up time : <5 minutes
Time to Result : 16-20 hrs

63
Q

AST E-Test

Growth along the entire gradient i.e. no inhibition ellipse indicates that the value is _____

A

greater than or equal to
(≥) the highest value on the scale

64
Q

AST E-Test

An inhibition ellipse that intersects below the lower end of the scale is read _____

A

less than (<) the lowest value

65
Q

AST E-Test

Streaking technique used to standardize inoculum

A

Overlapping Streaking Technique