Ast

Question 1

• Challenging the organism with antimicrobial agent in liquid environment
• express in MIC
  *kada tube domodouble ‘yong dilution

Answer 1

Broth dilution

Question 2

It uses small amount of broth

Answer 2

Broth microdilution

Question 3

0.05 to 0.1 ml - broth volume
48 hours for anaerobes - usage

Answer 3

Microdilution

Question 4

Equal to or greater than 1 ml

Answer 4

Macrodilution

Question 5

Temperature, medium and size of the 2 Broth Dilution method

Answer 5

35°C - 37°C for 16 - 24 hours
MH BROTH
5 x 10^5 CFU/ml
5 x 10^6 CFU/ml for anaerobes

Question 6

• most laboratories use commercially supplied Microdilution in which panels broth already supplement appropriate antimicrobial concentration
• Fresh (16-18 hours)
• 35 - 37°C

Answer 6

Microdilution

Question 7

Specific concentrations that separates/define the different categories

Answer 7

Breakpoints

Question 8

Panels that only contain antimicrobial concentrations

Answer 8

Breakpoint panels

Question 9

Advantage of breakpoint panels

Answer 9

Provide information to both
qualitative and
quantitative results
of your anti microbial agent

Question 10

Broth microdilution method of
Vancomycin,
Teicoplanin,
Quinn pristin-dalfopristin,
Linezolid,
maxi floxacin

Answer 10

> 0.25 - 32
0.125 - 16
0.125 - 16
0.125 - 16
0.063 - 8

Question 11

VITEK 2 method
Vancomy
teicoplanin
Quinn pristin-dalfopristin
linezolid
maxofloxacin

Answer 11

> 1-32
0.5 - 32
0.25 - 16
0.5-8
7 0.25-8

Question 12

• Anti microbial concentration and organism on an agar based medium
• allows examination of for more bacterial isolation per plate
  Can use bacterial isolates in one plate

Answer 12

Agar dilution

Question 13

Standard count of bacteria, advantage

Answer 13

• 1x10^4 CFU/ml
• MIC
• provides a means for determining MIC for
  Neisseria gonorrhoea, which does not grow sufficiently in broth

Question 14

• Suitable only to organisms that grows rapidly overnight
• non-commonly use to fastidious organism, only to non-fastidious

Answer 14

Disk diffusion (kirby-bauer)

Question 15

• Challenging bacterial isolates with antibiotic disks placed on the surface of an agar plate that has been seeded with a lawn of bacteria.
  • If agar is too thick antimicrobial agent diffuses down through the agar as well as outward resulting to a smaller zone sized
  • if agar is too thin inhibitor zones are larger molahinton agar

Answer 15

Disk diffusion

Question 16

Tinitignan Na result Na result sa disk diffusion

Answer 16

Zone of incubation (Z01)

Question 17

Inoculum preparation (use of pure culture)

Answer 17

• 4-5 colonies inoculate into broth medium incubate for 3-5 hours at 35 - 37°C
• 4-5 colonies, 16 - 24 suspendin broth on 0.9% saline solution

Question 18

Inoculum preparation

Use of standarized- size of inoculum

Answer 18

Turbidity standard
- 0.5 McFarland standard
- barium salfate suspension
Composition:
- 99.5 ml of 1% and o sulfuric acid
- 0.5 ml of 1.75% barium chloride
Standard size of inoculum:
- 15 x 108 ( FU /ml

Question 19

Inoculation & incubation

Answer 19

1. Surface of the plate is swabbed in 3 directions
2. Antibiotics disk are applied within 15 minutes
3. Inverted plates - incubate at 35.37°C
4. increased CO2 for fastidious bacteria
   6.incubation time maybe increased beyond 6 hours’_ for methicillin resistance staphylococci & vancomycin resistance enterococci

Question 20

Kirby Bauer disc diffusion method

Answer 20

1. inoculated agar plate
2. Addition of antibiotics disc
3. Measurement of the zone of inhibition

Question 21

Can tolerate high amount of salt

Answer 21

Staphylococci

Question 22

Can tolerate high amount of salt

Answer 22

Staphylococci

Question 23

• Commercially, prepared disks 6 mm in diameter should be used.
• Distilled water serves to dissolve most antibiotic powders, but chloramphenicol, rifampicin and erythromycin must first be dissolved in a small amount of ethanol
  • nitrofurantoin and sulfonamides in small volume of NaOH solution, trimethoprim in weak acid (acetic or lactic), and amoxicillin and ceftazidime in a small volume of saturated NaHC03
  • Disk should be taken out from refrigerator 1-2 hours before applying on the culture medium.

Answer 23

Antibiotic disk

Question 24

• Commercially, prepared disks 6 mm in diameter should be used.
• Distilled water serves to dissolve most antibiotic powders, but chloramphenicol, rifampicin and erythromycin must first be dissolved in a small amount of ethanol
  • nitrofurantoin and sulfonamides in small volume of NaOH solution, trimethoprim in weak acid (acetic or lactic), and amoxicillin and ceftazidime in a small volume of saturated NaHC03
  • Disk should be taken out from refrigerator 1-2 hours before applying on the culture medium.

Answer 24

Antibiotic disk

Question 25

1. Examine for the presence of confluent lawn of growth
   • a If POOR or NONCONFLUENT - repeat testing
   • 2. Examine for purity
   • a. If MIXED CULTURES - repeat testing
   • 3. A dark background and reflected light are used to examine the plate
   • 4. Measure the zone of inhibition in diameters for each antimicrobial agent using a ruler or caliper
   • 5. Interpret as “SUSCEPTIBLE”, “INTERMEDIATE” or “RESISTANT”

Answer 25

Reading and interpretation of result

Question 26

Different categories of sensitivity

Answer 26

Sensitive, intermediate & resistant

Question 27

Different categories of sensitivity

Answer 27

Sensitive, intermediate & resistance

Question 28

Staphylococcus species

Answer 28

Cefazolin <14 15-17 >18 clindamycin

Question 29

Pseudomonas aeruginosa and other non-fermenting gram negative

Answer 29

Amikacin, cefoperazone,, cefotaxine gentamicin