Point of Care Testing –
Clostridium difficle
Amita Patel
Guy’s and St Thomas’ NHS Foundation Trust
Project Aim
“Measuring the Clinical Value and impact of
C. difficle Point of Care testing (POCT) in
ICU and Care of Elderly wards”
(Project duration 18 months)
Project Stakeholders
Cepheid GeneXpert System
FDA approval for C. difficile 2009
First truly molecular POCT for CDI
Key End Points
► Carriage
and likelihood of Infection
► Predictability
► POCT
of virulence
– as a platform does it work?
► Turnaround
times and its impact on Patient
Key End points – Infection
► Measure
the prevalence of carriage of
(toxigenic and non-toxigenic C. difficile)
► Measure
likelihood of developing infection in
those that are carriers and,
► Establish
if source of infection is endogenous
or exogenous
End points – Virulence Perspective
► Reliability
of presumptive 027 identification
by comparison to PCR ribotyping
of tcdC deletions (and
association with severity)
► Prevalence
End points – POCT Perspective
► Acceptability
and ease of use of platform –
assessed by questionnaire to end-users
► Turnaround
time of test – assumed to be
time of PCR test duration
►collected
by research nurse compared with a
matched set of non study subjects (positive and
negative) from time of test being ordered to time of
result being released.
End points – Disease Perspective
► Severity
of CDI.
 Age and location matched cases
► Complications
 PMC, Colectomy etc
► All
cause mortality / mortality related to CDI
► Length
of Stay
Test time
Hands on time:
Time to final result:
approx 2 minutes
approx 45 minutes
Target Organisms
Are Isolated,
Concentrated
and Washed
Organism is Lysed
to release DNA
Disposable, enclosed
Micro-fluidic Cartridge
Sample is Pre filtered
to remove
large inhibitory debris
Raw Sample and Buffers
are Loaded into
Cartridge
(swab from stool sample)
DNA Molecules Mixed
with Amplification and
Detection Chemicals
(primers and probes)
Mixture
Delivered to Integrated
Reaction Tube for
Amplification and Detection
With I-CORE Module
Multiplex real-time PCR
3 Targets (plus internal positive control):
► Toxin B gene
► Binary toxin
► tcdC deletion
Specimen workflow
Patient Admission
consent & enrolled into study
Admission stool sample collected (<72 hours)
Symptoms of CDI – POCT PCR GeneXpert
&
Positive samples sent to lab for further work
Result interfaced with EPR via WinPath. Communicated to clinical
team and Infection Control – appropriate management
Positive Result
Story so far…………………………..
IT Issues:
Interface
Data Ownership
Network Points
Staffing Issues:
Restricted Recruitment
Bureaucracy
Acknowledgement:
►
►
►
Dr Simon Goldenberg
Cepheid
GSTS Pathology
Consultant Microbiologist GSTT Foundation Trust Hospital