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CTX-M -

(Detection in

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INTRODUCTION1.E.coli are the most frequently

associated with ESBL.

2.In the Class A ESBLs based on

Ambler Classification.

3.ESBLs are enzmes that mediateresistance to extended-spectrum

(third generation) cephalosporinsand monobactams.

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METHOD

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Antimicrobial SusceptibilityStandard Disc Diffusion Method

1. In-vitro sensitivity testing usingestablished NCCLS (National Committefor Clinical Laboratory Standards)

procedure is carried out with :Ceftazidime (30 g)

Cefotaxime (30 g)

Ceftriaxone (30 g)Aztreonam (30 g)

Cefpodoxime (10 g)

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Antimicrobial SusceptibilityStandard Disc Diffusion Method

2. Zone diameters are read usingthe revised NCCLS document where

any zone within grey zone areconsidered as a probable ESBLproducing strain which requiring

henot ic confirmator testin

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Antimicrobial SusceptibilityStandard Disc Diffusion Method

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Antimicrobial SusceptibilityStandard Disc Diffusion Method

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Double Disk Synergy / DiskApproximation Method

1. This method uses multipletarget disc with clavulanic acid

disc or a single cefpodoximedisc with clavulanic acid disc.

2. Mueller Hinton agar plate is

inoculated with a suspension(0.5 McFarland) made from anovernight agar plate of the test

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Double Disk Synergy / DiskApproximation Method

3. Disc containing the standard, Ceftazidime (30 g)

Ceftriaxone (30 g) Aztreonam (30 g) Cefpodoxime (10 g)

4. Plates are then incubated

overnight at 35C.5. Enhancement of zone inhibition isindicative of presence of an ESBL

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Double Disk Synergy / DiskApproximation Method

ZoneEnhanceme

nt

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Disc Diffusion Method

1. Ceftazidime (30 g) versusceftazidime / clavulanic (30

/ 10 g) and cefotaxime (30g) versus (cefotaxime /clavulanic acid (30 / 10 g)

are placed onto a Muller Hinton agar plate lawnedwith the test organism and

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Disc Diffusion Method

2. Result :

Clavulnic acid

restores activity ofcefotaxime orceftazidime orboth

3. QC :

E.Coli ATCC 25922

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Disc Diffusion Method

2. E-test combination strips,example ceftazidime / ceftazidime clavulanic acid and cefotaxime /

cefotaxime clavulanate areemployed to perform thephenotypic confirmatory testing

3. Strips are inoculated on thesurface of the agar plate andincubated overnight

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Disc Diffusion Method

Ceftaz/CA

Ceftaz

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Others Method

Molecular detection PCR and sequencing

The gold standard

Can detect all variants Easy to perform Labor intensive

Isoelectric focusing (IEF) Automated System

Microscan, Vitek2 & Phoenix