AST

Question 1

What are the substances that inhibit, kills or destroy microorganisms?

Answer 1

Antimicrobial agents

Question 2

What are the two sources of Antimicrobial Agents?

Answer 2

1. Microorganisms (bacteria/fungi)
2. Chemically synthesized

Question 3

Antimicrobial agents according to spectrum of action: (2)

Answer 3

1. Narrow spectrum
2. Broad spectrum

Question 4

Spectrum of action:

Limited spectrum of action

Answer 4

Narrow spectrum

Question 5

Spectrum of action:

Examples of Narrow Spectrum: (6)

Answer 5

1. Penicillin G
2. Bacitracin
3. Clindamycin
4. Erythromycin
5. Polymyxin B
6. Vancomycin

Question 6

Spectrum of action:

Wide spectrum of action

Answer 6

Broad spectrum

Question 7

Spectrum of action:

Action against Gr(+) and Gr(-) bacteria

Answer 7

Broad spectrum

Question 8

Spectrum of action:

Examples of Broad Spectrum: (3)

Answer 8

1. Tetracycline
2. Ampicillin
3. Cephalosporins

Question 9

Spectrum of action:

Disadvantage of Broad Spectrum:

Answer 9

Destruction/inhibition of the normal flora leading to superinfection.

Question 10

Antimicrobial agents according to action: (2)

Answer 10

1. Bacteriocidal agents
2. Bacteriostatic agents

Question 11

According to action:

• Kill or destroy the microorganisms
• Used in life-threatening infections and in infections in immunosuppressed patients

Answer 11

Bacteriocidal agents

Question 12

According to action:

Inhibits the growth of microorganisms

Answer 12

Bacteriostatic agents

Question 14

Performed on bacteria isolated from clinical specimens

Answer 14

AST

Question 15

AST stands for

Answer 15

Antibiotic Susceptibility Testing

Question 16

AST provides in-vitro testing of a bacterial pathogen to a setof available antibiotics to determine it’s

Answer 16

antibiogram

Question 17

antibogram is also knows as

Answer 17

susceptibility profile

Question 18

TRUE OR FALSE

AST is performed on a bacterial isolate that is not the probable cause of infection

Answer 18

FALSE

should be the probable cause of infection

Question 19

TRUE OR FALSE

AST is not performed on bacterial isolates that are predictably susceptible to a certain agent

Answer 19

TRUE

Question 20

increase or decrease

AST provides information on the _______ of the antimicrobial susceptibility

Answer 20

decrease

Question 22

Body Site

do not perform AST on bacteria isolated from it’s

Answer 22

natural habitat

Question 23

fill in the blanks

isolation from a ________ is less likely to be contaminated

Answer 23

pure culture

Question 24

indicator in urine that’s possibly due to contamination

Answer 24

> 2 species at > 10⁵ CFU/mL

Question 25

Host Status

Normal Flora might be the cause of the cause of the infection in cases of

Answer 25

immunocompromised patients

Question 26

Standardization of AST

3 important purposes:

Answer 26

1.** To optimize bacterial growth conditions **to ensure that the inhibition of growth can be attributed to the antimicrobial agent
2. To optimize conditions for maintaining antimicrobial integrity and activity, attributing the failure to inhibit bacterial growth to organism-associated resitance
3. To maintain reproducibility and consistency in the resistance profile of an organism, regardless of what laboratory performs the test

Question 27

Standardization of AST

Standardized Components

Answer 27

• Bacterial inoculum size
• Growth medium
  - pH
  - Cation concentration
  - Blood and serum supplements
  - Thymidine content
• incubation atmosphere
• incubation temperature
• incubation duration ‘antimicrobial concentrations

Question 28

Standards are updated and published by

Answer 28

CLSI

Question 29

CLSI stands for

Answer 29

Clinical and Laboratory Standards Institute