Antimicrobial Susceptibility Testing - Disk Diffusion

191 Pages·2011·7.28 MB·English

by  Dr. Babak Valizadeh

Antimicrobial Susceptibility Testing
Disk Diffusion

Babak Valizadeh,
DCLS
[email protected]
1390 / 09 / 10
2011.12.01

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CLSI - M02-A10 / 2009
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CLSI – M100-S21 / 2011
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Antimicrobial Susceptibility Testing
CLSI : Clinical and Laboratory Standards Institute

 CLSI (2005) , formerly NCCLS (2004)

 Antimicrobial Susceptibility Testing (AST) vs. Antibiogram

Susceptible vs. Sensitive

 EUCAST :European Committee on Antimicrobial Susceptibility Testing
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Terminology & Definitions
Susceptible
– a category that implies
that isolates are inhibited by the usually
achievable concentrations of
antimicrobial agent when the
recommended dosage is used for the site
of infection

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Terminology & Definitions
Intermediate
– a category that
includes isolates with antimicrobial
agent MICs that approach usually
attainable blood and tissue levels
and for which response rates may be
lower than for susceptible isolates.


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Terminology & Definitions
Intermediate implies clinical efficacy
–
in body sites where the drugs are
physiologically concentrated (eg,
quinolones and β-lactams in urine) or
when a higher than normal dosage of a
drug can be used (eg, β-lactams)
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Terminology & Definitions
Intermediate This category also
–
includes a buffer zone, which should
prevent small, uncontrolled, technical
factors from causing major
discrepancies in interpretations,
especially for drugs with narrow
pharmacotoxicity margins
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