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Clostridium difficile:Clostridium difficile:

Laboratory Laboratory InvestigationsInvestigations

Tony Tony KormanKorman

National Clostridium difficile WorkshopNational Clostridium difficile Workshop

20 August 201020 August 2010

Introduction to Laboratory testing Tony Introduction to Laboratory testing Tony KormanKorman

ANZ Clostridium difficile Laboratory Survey ANZ Clostridium difficile Laboratory Survey Results and Recommendations for Testing and Results and Recommendations for Testing and Laboratory Practice John FergusonLaboratory Practice John Ferguson

ASID Guidelines for Management of C. ASID Guidelines for Management of C. difficile infection Allen Chengdifficile infection Allen Cheng

C. difficile: C. difficile: Diagnosis Diagnosis

Laboratory Laboratory Investigations Investigations

C. difficile detectionC. difficile detection

C. difficile toxin detectionC. difficile toxin detection

Laboratory Laboratory Investigations Investigations

C. difficile detectionC. difficile detection

CultureCulture

Antigen detectionAntigen detection

C. difficile culture C. difficile culture Limited clinical value!Limited clinical value!

Several days for resultsSeveral days for results

No differentiation b/w No differentiation b/w toxigenictoxigenic & & nonnon--toxigenictoxigenic

Antimicrobial susceptibilityAntimicrobial susceptibility

Molecular typing, epidemiologyMolecular typing, epidemiology

C. difficile GDH C. difficile GDH antigen antigen

<2 hours<2 hours

>90% sensitivity>90% sensitivity

screening testscreening test

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Laboratory Laboratory Investigations Investigations C. difficile toxin detectionC. difficile toxin detection

ToxigenicToxigenic cultureculture

Cell Cell cytotoxicitycytotoxicity neutralisatonneutralisaton assay assay (CCNA)(CCNA)

Enzyme Immunoassay (EIA)Enzyme Immunoassay (EIA)

ImmunochromatographicImmunochromatographic testtest

PCRPCR

Cell Cell cytotoxicitycytotoxicityneutralisatonneutralisaton assayassay

““Gold standardGold standard””

Specific (99Specific (99--100%)100%)

Cell culture expertiseCell culture expertise

2424--48 hours48 hours

Cell Cell cytotoxicitycytotoxicityneutralisatonneutralisaton assayassay

““Gold standardGold standard””

Specific (99Specific (99--100%)100%)

Cell culture expertiseCell culture expertise

2424--48 hours48 hours

Enzyme Immunoassay Enzyme Immunoassay (EIA)(EIA)

SpecificSpecific

4 hours4 hours

No cell culture expertiseNo cell culture expertise

Sensitivity 60Sensitivity 60--90%90%

ImmunochromatographiImmunochromatographicc Tests (ICT)Tests (ICT)

SpecificSpecific

<1 hour<1 hour

No expertise requiredNo expertise required

Sensitivity 50Sensitivity 50--65%65%

Polymerase Chain Polymerase Chain Reaction (PCR)Reaction (PCR)

<2 hours<2 hours

SpecificSpecific

SensitiveSensitive

CostCost

BD BD GeneOhmGeneOhm

Up to 6 specimens per runUp to 6 specimens per run

GeneXpertGeneXpert

result <1 hourresult <1 hour

18 18 bpbp deletiondeletion

GeneXpertGeneXpert