[LAB] Exercise 8B: AST: Broth Macrodilution or Macrobroth Dilution

Question 1

what type of dilution is one of the conventional testing methods used in AST?

Answer 1

Broth dilution

Question 2

This is a technique that uses a standardized amount of test inoculum present in Mueller Hinton Broth (MHB) and a selected antimicrobial agent.

Answer 2

Broth dilution

Question 3

What standardized test inoculum is used in Broth dilution?

Answer 3

Mueller Hinton Broth and Selected antimicrobial agent

Question 4

T/F: The antimicrobial agent is diluted five-fold in the test.

Answer 4

F.
two-fold in the test only

Question 5

T/F: The minimum inhibitory concentration (MIC) is expressed in mg/dl

Answer 5

F.
µg/mL

Question 6

This is the lowest concentration of antimicrobial agent that completely inhibits visible growth

Answer 6

Minimum inhibitory concentration (MIC)

Question 7

T/F: The MIC can be detected semi-automated

Answer 7

trew

Question 8

MIC can be detected v_______, a_______, or s__________ method

Answer 8

visually
automated or semi-automated

Question 9

Name three interpretative categories once MIC has been determined

Answer 9

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

Question 10

Name two categories of broth dilution

Answer 10

Broth microdilution (microbroth dilution)
Broth macrodilution (macrobroth dilution)

Question 11

T/F: Main difference between broth microdilution and broth microdilution is on the volume of the MIC

Answer 11

F.
Volume of the MHB used dapat :)

Question 12

T/F: In exercise 8B, broth microdilution was used.

Answer 12

F.
Broth macrodilution
(check the title of the experiment for validation <3) HAHAHA

Question 13

T/F: Sterile 12mm x 100mm test tubes with screw caps were used in this experiment.

Answer 13

F.
13mm x 100mm dapat :)

Question 14

Yes/No: In this experiment 8B, do we need to standardize the inoculum to a 0.5 McFarland Standard?

Answer 14

Yes.

Question 15

T/F: The test antibiotic used in this experiment was Amoxicillin 20 U/mL

Answer 15

F.
Penicillin (working solution of 20 U/mL)

Question 16

T/F: The test culture must grow on BAP

Answer 16

T.

Question 17

T/F: For other test antibiotics a 200 µg/mL should be your working solution

Answer 17

T.

Question 18

The adjusted inoculum is then diluted to what ratio?

Answer 18

1:200

Question 19

T/F: The adjusted inoculum is done by adding 0.1 mL of the standardized inoculum to 19.9 mL of MHB Broth.

Answer 19

T.

Question 20

T/F: In the preparation and standardization of the Inoculum, the final bacterial concentration is approximately 4 x 10^5 CFU/mL

Answer 20

T.
5 x 10^5 CFU/mL

Question 21

In the test proper, test tube 1-10 will be used for the ______?

a. actual test
b. control tubes

Answer 21

a. actual test

Question 22

In the test proper, test tube 11-13 will be used for the ______?

a. actual test
b. control tubes

Answer 22

b. control tubes

Question 23

In the test proper, control tube - test tube 11 is the ______?

a. antibiotic control (AC)
b. broth control (BC)
c. inoculum control (IC)

Answer 23

c. inoculum control (IC)

Question 24

In the test proper, control tube - test tube 12 is the ______?

a. antibiotic control (AC)
b. broth control (BC)
c. inoculum control (IC)

Answer 24

b. broth control (BC)

Question 25

In the test proper, control tube - test tube 13 is the ______? a. antibiotic control (AC) b. broth control (BC) c. inoculum control (IC)

Answer 25

a. antibiotic control (AC)

Question 26

In the test proper, the test tubes should be incubated at what degree Celsius?

Answer 26

35°C - 37°C

Question 27

T/F: Mix each tube and incubate them at 35-37°C ambient air for 18-24 hrs.

Answer 27

T.

Question 28

T/F: We observe visible growth in the form of TURBIDITY

Answer 28

T.

Question 29

T/F: prior to interpretation, observe if the ACTUAL TEST are working properly

Answer 29

F. CONTROL TUBES

Question 30

T/F: Test tube 11 - must show VISIBLE GROWTH

Answer 30

T. because inoculum control

Question 31

Test tube 12 - must show VISIBLE GROWTH or NO VISIBLE GROWTH?

Answer 31

NO VISIBLE GROWTH because broth control

Question 32

Test tube 13 - must show VISIBLE GROWTH or NO VISIBLE GROWTH?

Answer 32

NO VISIBLE GROWTH because antibiotic control

Question 33

T/F: In determining the MIC, we determine the tube with the HIGHEST antibiotic concentration

Answer 33

F. LOWEST

Question 34

In determining the MIC, we determine the tube with the lowest antibiotic concentration showing _______? (visible growth or no visible growth)

Answer 34

no visible growth

Question 35

T/F: In the determination of MBC, we pipette 0.01 mL from each test tube with no visible growth and subculture to individual CAP plates

Answer 35

F. BAP plates

Question 36

T/F: same with MIC, we incubate the plates for 18-24 hrs at 35-37°C ambient air

Answer 36

T.

Question 37

MIC or MBC: It has the lowest antibiotic concentration, which results in 99% killing of organisms.

Answer 37

MCB (Minumum Bactericidal Concentration)

Question 38

MIC or MBC: It can be determined by identifying the plate with the lowest antibiotic showing no visible growth

Answer 38

MCB (Minumum Bactericidal Concentration)

Question 39

T/F: In broth macrodilution test, fastidious bacteria are required

Answer 39

T.

Question 40

The breakpoint of growth inhibition is visible in what tube/s? (choose only 2 tubes from tubes 1-10)

Answer 40

between tube 5 and tube 6

Question 41

What is the main difference between Broth microdilution test and Broth macrodilution test?

Answer 41

Volume of MHB (Mueller-Hinton Broth)

Question 42

MIC or MBC: Lowest concentration that prevents the in vitro growth of bacteria

Answer 42

MIC (Minimum Inhibitory Concentration)

Question 43

MIC or MBC: Test tube that shows the lowest concentration without any colony growth

Answer 43

MBC (Minimum Bactericidal Concentration)