Investigation of C. difficile outbreaks - how molecular epidemiology can help us?
George Broukhanski, Ph.D. Molecular Specialist Public Health Ontario Laboratories
C. difficile education day April 21, 2016
Kwong JC, Crowcroft NS, Campitelli MA, Ratnasingham S, Daneman N, Deeks SL, Manuel DG. Ontario Burden of Infectious Disease Study Advisory Group; Ontario Burden of Infectious Disease Study: An OAHPP/ICES Report
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Ontario Agency for Health Protection and Promotion, Provincial Infectious Diseases Advisory Committee.
Annex C – Testing, Surveillance and Management of Clostridium difficile. Annexed to: Routine Practices and
Additional Precautions in All Health Care Settings. Toronto, ON: Queen’s Printer for Ontario; 2013
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Testing for Diagnosis of C. difficile Infection • Cultures for C. difficile are not routinely done. Laboratory testing for
CDI usually involves detection of the cytotoxins A and B produced by
C. difficile by enzyme immunoassay (EIA) toxin or detection of the C.
difficile toxin gene by molecular methods such as polymerase chain
reaction (PCR)
• Rapid turnaround time for C. difficile testing and reporting is essential
and should be pre-arranged with the microbiology laboratory serving
the health care setting. Ideally, turnaround time should be less than
24 hours and the test should be available seven days per week
Ontario Agency for Health Protection and Promotion, PIDAC. Annex C
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Case Definitions for Surveillance and Reporting
• Surveillance Definition for Attributable CDI Surveillance definitions may
differ between jurisdictions. It is important to note that the time frames
associated with these definitions, while useful for surveillance purposes,
are arbitrary and may not truly reflect C. difficile acquisition in the facility.
• CDI Attributable to Your Facility: The symptoms of CDI were not present on
admission (i.e., onset of symptoms > 72 hours after admission) or the
infection is present at the time of admission but is related to a previous
admission to your facility within the last four weeks.
• CDI Not Attributable to Your Facility: The symptoms of CDI were present on
admission or < 72 hours after admission and there was no admission to
your facility within the last four weeks OR The symptoms of CDI recur
within two months of the last infection (relapse)
Ontario Agency for Health Protection and Promotion, PIDAC. Annex C
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Pulsed Field Gel Electrophoresis (PFGE)
Labour intensive – takes up to
10 days to get results
Requires special equipment,
casting gels, processing
plugs, taking pictures,
interpretation etc.
Lacks discriminatory power in
outbreaks caused by NAP1
strains
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PFGE typing of C. difficile isolates
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Multiple-Locus Variable number of tandem repeats Analysis (MLVA)
C difficile chromosome
tandem repeats
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MMLVA typing of C. difficile isolates
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MLVA analysis of isolates from 3 hospital outbreaks
Hospital 1 – mixture of NAP1 and non-NAP1
Hospital 2 – heterogenous NAP1
Hospital 3 – homogenous NAP1
NAP1 NAP7
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Clustering of C. difficile isolated during an outbreak
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MLVA analysis of isolates from a single specimen
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Observed variations in isolates from a single specimen
Monoclonal Low diversity High diversity
Minimum
spanning
trees
Cluster
analysis
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Ribo-MMLVA typing of outbreak isolates
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Thank you
