Tracking Foodborne Outbreaks in Wisconsin Using PulseNet Fingerprints

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Tracking Foodborne Outbreaks in Wisconsin Using
PulseNet Fingerprints

• Terry Kurzynski, MS
• Advanced Microbiologist
• Wisconsin State Laboratory of Hygiene
• WSLH Audio Conference Program

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The Public Health Burden of Foodborne Disease in
the US

• Mead et al 1999 - Emerg Infect Dis 1999 5
• 76 million cases per year
• 325,000 hospitalizations
• 5000 deaths
• Cost 8-10 billion/year
• Known pathogens - 14 million (19)
• Unknown pathogens - 62 million (81)

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Trends in Foodborne DiseasePercent of Food
Spending by Site
Food Review 1623-7, 1993
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Examples of Fresh Produce and Juice which
Bacterial Pathogens Have Been Isolated
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PFGE Method
Step

• Liquid suspension of bacteria
• Encase in agarose plug
• Lyse with detergent and protease
• Wash away detergent and protease
• Digest with restriction enzyme
• Separate restriction fragments of genome DNA on
  PFGE apparatus

Comment
Protects structure of genome DNA Destroys cell
membrane and protein Allows restriction enzyme
to work properly Digests genome and plasmids
into 15-20 fragments Size range 20 800
kilobases
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Plug Mold
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Specimen Slice
Comb
Gel
Casting Stand
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Pump
CHEF Mapper
Cooler
Electrophoresis Chamber
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Gel Doc Imaging System
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PFGE Analysis of E.coli O157H7 isolates
M Milwaukee outbreak O Other outbreak ?
marker/internal reference
M
M
M
M
O
O
O
?
?
?
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Pre-Normalization
Post-Normalization
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What is PulseNet?

• A national network of public health laboratories
• State health departments
• Local health departments
• Federal agencies (CDC, USDA, FDA)
• Perform standardized molecular typing of
  foodborne disease-causing bacteria by PFGE
• Sharing DNA fingerprints electronically
• Enhancing foodborne disease surveillance

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PulseNet Enhances Surveillance

• Detecting outbreaks by identifying cases with
  indistinguishable PFGE patterns
• Linking apparently unrelated outbreaks
• Speeding outbreak investigations through focusing
  efforts on cases with indistinguishable PFGE
  patterns
• Monitoring for illnesses associated with a
  product retail samples, recalls

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single food supplier
outbreak in New York
outbreak in California
outbreak in Wisconsin
same PFGE pattern
-Hypothesis for disease transmission -Test food
samples with PFGE
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PulseNet WebBoard E. coli Conference

• Example 2002 WI Outbreak
• August 2002
• cluster among campers in WI
• 7 of 20 campers ill 3 confirmed E. coli O157H7
  infection
• 5 response postings within 1 day
• September 2002
• a second cluster appears in WI
• 25 response postings within 30 days

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E. coli Cluster Analysis

• Cluster analysis compares isolates that have been
  uploaded to the PulseNet National E. coli
  Database within the past 60 days.

Isolates from WI cluster 1
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Comparing Isolates in the E. coli National
Database

• Are there any recent indistinguishable patterns
  submitted by USDA or FDA?
• Ground beef isolates received from USDA were
  indistinguishable from the outbreak pattern by
  two enzymes

Patient isolate
Food isolate
WI cluster 2 primary enzyme (XbaI)
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2002 WI E. coli Outbreak 2 Clusters
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Reporting to CDC Epidemiologists and PHLs

• Communication is important
• Example Summary
• The Cluster 2 outbreak was epidemiologically
  linked to ground beef products originating from a
  production plant in WI. During the time period of
  9/13/02 to 10/28/02, eighty-five isolates were
  received from WI (45), MN (14), MI (13), NY (7),
  PA (2), CO (1) and IA (1).
• Outcome Approximately 2.8 million pounds of
  ground beef were recalled from the WI production
  plant.

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Incidence of E. coli O157 infections, by state,
1999-2002
Isolates /100,000 pop/year
3.0 6.2 1.7 2.9 0.9 1.6 0.2 0.8
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Other Bacteria Tested By PFGE at the WSLH

• Neisseria meningitidis
• Bordetella pertussis
• Staphylococcus aureus (MRSA)
• Legionella pneumophila

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Acknowledgements

• I wish to thank the following people for their
  assistance in preparation of my slides Dominic
  Vacca, Dave Warshauer, Bill Kurth and Kim Kreiger.