Agar diffusion method Basmah almaarik

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Agar diffusion methodBasmah almaarik

• Lab 2

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Antibiotic Sensitivity Test

• Method
• 1) Broth dilution
• 2) Agar diffusion (solid)
• -a) Kirby-Bauer test ( disc test)
• - b) Stocks methods

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a) Kirby-Bauer Test (disc diffusion test) (Solid
agar test)

• Fresh organism suspended in broth.
• (0.5 MaCfaraland standard)
• Swab organism all over the plate evenly.
• Place discs containing specified concentration of
  different antibiotics on the plate.

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Kirby-Bauer Test

• Incubate 37C x 24hr
• Measure diameter of Clear zone around the disc
  . (Inhibition zone)
• Use tables to assess if zone size indicates
• resistance or sensitivity to that antibiotic

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Kirby-Bauer Test (disc diffusion test)
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(No Transcript)
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How to Streak the sensitivity plate

• Immerge swab then remove excess by pressing
  against wall of tube
• Do one line in the center of plate by swab then
  spread evenly
• Add antibiotic disks using needle
• Always work near flame to avoid contamination
• Dont put disk near the edge

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B) Stockes Method

• Interpretation based on comparison between
• zones seen with the test organism those of the
  known sensitive control.

Q.C organism
Antibiotic disk
Test organism
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Results of Stockes Method

• T gt C or T C ? Sensitive
• Tlt C ? Resistance

Test organism
Control organism
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Antibiotic Dispenser (Disk Dispenser)
http//rfdp.seafdec.org.ph/publication/manual/anti
biotics/chapter2.html
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Antibiotic ring
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Automatic colony counting and zone measuring
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Work done by students

• Prepare 2 Kirby-Bauer technique plates
• Using disc dispenser
• Using antibiotic ring technique
• Prepare 1 stocks method plate using control and
  test organisms given to you and inoculate 3
  antibiotics using the needle.
• Next day measure the inhibition zone in each
  plate and determine whether its sensitive or
  resistance by Zone Diameter Interpretative
  Standards

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• Thank You