Emerging Options to Control E. coli O157:H7 Pre-Harvest

1
Emerging Options to Control E. coli O157H7
Pre-Harvest

• Guy H. Loneragan
• Epidemiologist
• West Texas AM University
• Canyon, Texas, USA

SteakExpert June 24-25, 2009, Angers, France
2
Background

• Born and raised in Mudgee, New South Wales,
  Australia
• Parents have a 500 hectare property
• Cattle, sheep, crops, 15 hectares
  shiraz/cabernet
• Veterinary training at the University of Sydney,
  Australia
• Degree awarded 1994
• Epidemiology training at Colorado State
  University, Fort Collins, Colorado, US
• MS and PhD awarded 1998 and 2001, respectively
• West Texas AM University, Canyon, Texas, USA
• Focus on food safety, particularly prior to
  harvest
• E. coli O157, Salmonella, antimicrobial drug
  resistance

3
Comments Prior to Presentation

• E. coli O157H7 and non-O157 VTEC are not
  geographically constrained
• Found worldwide
• E. coli O157H7 is the primary cause of HUS in
  North America, many EU member states, South
  American countries, Australia, etc.
• Focus of my research has been on the North
  American production system
• Mostly confined feeding
• As such, most of the information I present is
  related to confined cattle feeding operations
  (i.e., feedlots, dairies)
• Some of the options may provide areas for further
  discussion and opportunities for France and rest
  of EU

4
Discussion

• E. coli O157H7 and non-O157 VTEC should be
  thought of as commensal organisms of cattle
• In other words, they are (likely) beneficial
  bacteria of cattle and potentially other
  ruminants
• In many instances, we encourage commensals
• Historically, we have not had to ponder too much
  about how to eliminate/reduce commensal bacteria
• Over time, we have developed tools to identify
  and control pathogens
• For example, Salmonella Typhimurium, M. bovis,
  Brucella
• Initial pre-harvest efforts to control E. coli
  O157H7 was to approach the problem as if it were
  a pathogen
• Isolation, containment, prevent exposure
• Not very effective

5
Chronology

• From a North American perspective, our initial
  flawed approach resulted in effective pre-harvest
  interventions arising relatively late
• Most initial control at abattoirs
• Highly effective but still failures occurred
• Increase in illnesses and recalls because of
  contamination in 2007
• Finally, we began to understand the ecology of
  VTEC O157 and understood that it was not a
  pathogen for cattle
• Consequently, interventions were developed that
  exploit some tool or characteristic of the
  bacterium
• Very specific (vaccine) or broad sweeping
  approaches (chlorate)

6
Chronology

• There now exists a large collection of scientific
  literature that provides evidence that it is
  possible to control E. coli O157 in cattle
• Use of appropriate interventions given the
  production system can reduce the burden of E.
  coli O157 leaving farms and entering abattoirs
• As an epidemiologist, I am most interested in
  field studies

7
Interventions

• A variety of interventions have been
  developed/evaluated
• Biological
• DFM
• Bacteriophage
• Chemical
• Neomycin
• Sodium chlorate
• Immunomodulation
• Vaccine
• Discussion predicated that I am most interested
  in field studies of effect
• Challenges models do not take into account
  important determinants of shedding (namely cohort
  level)

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L. acidophilus-based probiotics

• Continuously fed to cattle
• Only suitable to confinement operations
• In the USA, achieved FDA GRAS status
• BUT no FDA-approved label claim for control of E.
  coli O157
• Most widely evaluated product is that of
  Nutrition Physiology Corporation
• BOVAMINE, includes LAB NP51 (NPC 747)
• 9 peer-reviewed manuscripts demonstrating
  significant reduction using L. acidophilus NP51
• Articles from 4 groups of researchers
• Systematic review, Sargeant et al, ZPH
  200754260
• Standardized approach
• Evidence for efficacy of LAB NP51

9
Meta-analysis

• Meta-analysis is a method to combined data from
  different studies
• Uncertainty associated with individual studies
• Meta-analysis combined data, reduces uncertainty,
  provides best-estimate of effect
• Powerful analytical approach
• It is not, however, perfect and can be affected
  by statistical biases
• Performed meta-analysis of NP51
• Both published and unpublished data

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Summary of LAB NP51
RR Fecal Product Efficacy Lower 95 CL Upper 95 CL P value
0.53 47 0.44 0.63 lt0.01
P value assoc. with Q stat 0.15 Between study variance 0.06 P value assoc. with Q stat 0.15 Between study variance 0.06 P value assoc. with Q stat 0.15 Between study variance 0.06 P value assoc. with Q stat 0.15 Between study variance 0.06 P value assoc. with Q stat 0.15 Between study variance 0.06
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Summary of LAB NP51
RR Hides Product Efficacy Lower 95 CL Upper 95 CL P value
0.60 40 0.49 0.75 lt0.01
P value assoc. with Q stat 0.46 Between study variance 0.00 P value assoc. with Q stat 0.46 Between study variance 0.00 P value assoc. with Q stat 0.46 Between study variance 0.00 P value assoc. with Q stat 0.46 Between study variance 0.00 P value assoc. with Q stat 0.46 Between study variance 0.00
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Feedlot studies of NP51

• Meta-analysis average reduction
• 40 reduction of prevalence in feces (26.5 versus
  12.7)
• 47 reduction of prevalence on hides (20.4 versus
  11.3)
• Some evidence for an effect on concentration
• Fecal load in positive animals reduced by greater
  99.5
• NP51 was associated with reduced number of
  positive animals and reduced number of bacteria
  in animals that remained positive

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LABm and Control of E. coli O157H7 in Ground Beef
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Another Probiotic PROBIOS FSEnterococcus, Chr.
Hansen

• Fed for last 14 days on feed
• Average reduction
• 56 feces
• Hides not evaluated
• Has FDA GRAS status in USA
• Limited use
• Limited availability???

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Direct-Fed Microbials

• Easy adoption within confined feeding operations
• Efficacy in a variety of feeding systems
• Dairies, feedlots, etc.
• While not dramatic in all studies, evidence of
  improvements in animal performance
• No easy implementation for pastured cattle
• No USA FDA label claim for E. coli O157 control
• Regulatory agencies in the USA will never
  endorse
• Better positioned if had an approved label claim
  for control/reduction of E. coli O157

16
Immunomodulation

• Is it possible to trick an animal into
  developing immunity to a commensal?
• In the past, I believed this to be impossible
• Three products have been evaluated in commercial
  settings
• Vaccine 8 peer-reviewed manuscripts
• 7 showed significant reduction in
  shedding/colonization
• Data generated from 3 groups of researchers

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Bioniche ProductOntario, Canada

• Vaccination against Type III secreted proteins
• Tool the bacteria use to colonize the gut
• Field work really began with study published by
  Potter et al., 2004

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Bioniche ProductOntario, Canada
Year of cattle Regimen Outcome Odds ratio Vaccine efficacy P-value Comments
2002 192 3-dose Feces 0.36 59 0.04 bench-top vaccine
2003 608 1-dose Feces 0.25 68 0.0001
2-dose Feces 0.26 67 0.0001
3-dose Feces 0.20 73 0.0001
0-dose Feces 0.36 59 0.0003 herd immunity?
2003 1003 3-dose TRM 0.67 NS gt0.10 ranch vaccination, low prevalence
Feces 0.81 NS gt0.10 ranch vaccination, low prevalence
2004 288 3-dose TRM 0.014 98 0.0001
Feces 0.81 NS 0.56 low prevalence
2004 718 2-dose TRM 0.07 83 0.0008
20,556 ROPES 0.59 27 0.004 19 NE feedlots
2005a 504 2-dose Feces 0.35 62 0.002 Between pens
TRM 0.71 NS 0.65
Hides 0.45 54 0.005
2005b 168 2-dose Feces 0.40 58 0.005 Within pens
TRM 0.73 NS 0.48
Hides 0.70 28 0.06
2006 480 2-dose Feces 0.66 33 0.09 Dose effect
3-dose Feces 0.34 65 0.002
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Bioniche ProductOntario, Canada

• Available in Canada as Econiche
• Soon to be Conditionally licensed in the USA
• Cannot use trade name
• In studies in USA, it has resulted in significant
  reductions in burden of E. coli O157H7
• In feces
• At TRM (RAMS, RAJ)
• On ROPES (an indication of animal to
  contact-surface transfer)
• On hides (both at the feedlot and at the packing
  plant)
• Canadian study (not Bioniche product) found no
  effect
• Van Donkersgoed et al., CVJ 2005
• Likely manufacturing issues rather than an
  efficacy issue

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Epitopix ProductMinnesota, USA
E. coli O157

• Targets the mechanism by which some bacteria
  acquire iron from environment
• E. coli O157, Salmonella
• Iron largely acquired via siderophore receptor
  porin proteins (SRP)
• Passive, gradient dependent
• At low concentrations, energy dependent

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SRP Technology

• Research suggests it is possible to restrict iron
  acquisition
• via immunity against cell-surface SRP proteins
• Competitive disadvantage
• Vaccine consists of purified SRPs as antigens
  (Epitopix, 2004)
• Technology developed for Salmonella in turkeys,
  then cattle, and now E. coli O157

E. coli O157
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Epitopix ProductMinnesota, USA

• Initial field study suffered from low prevalence
  so hard to make statistical comparisons
• Significant reductions on hides or cattle
  positive at any site
• Subsequent study changed from 2-dose to 3-dose
  regimen

• Feces 39
• RAJ 48
• Hides 70

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Epitopix ProductMinnesota, USA
P0.28
P0.13
Plt0.01
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Epitopix ProductMinnesota, USA
P0.01 98 reduction in MPN
P0.28
P0.13
Plt0.01
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Epitopix ProductMinnesota, USA

• Available in USA
• Conditionally licensed
• In studies in USA, it has resulted in significant
  reductions in burden of E. coli O157H7
• In feces
• On hides
• In concentration of E. coli O157
• Ongoing research in production system in USA
• Cows gt suckling calves gt feedlot
• Opportunity for further research in pastured
  cattle outside of North America

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Ft. Dodge

• Evaluated once (and published) in commercial
  settings FPT 200626393-400
• Only 3 pens per exposure and unusual analysis
• Unclear what to conclude except appeared
  beneficial

• Feces 68
• Hides 50

• Other vaccines UNM technology
• Licensed to a Colorado company

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Immunomodulation

• Strong evidence that it is possible to trick an
  animal into developing immunity to a commensal
• Bioniches Econiche licensed in Canada
• Pending conditional license in the USA
• Epitopix product conditionally licensed in the
  USA
• Dose response
• 3 doses appears to provide greatest response
• 2 doses may be more effective when whole herds
  vaccinated
• Easily administered to cattle in almost all
  production systems
• More doses associated with more handling of
  animals
• Appears to be slightly more efficacious than LAB

28
Sodium Chlorate

• Generated a substantial amount of interest in
  North America
• Suitable for confined animal feeding operations
• Acts as a suicide substrate for bacteria that
  respire using nitrate reductase
• Chlorate gtgtgt Chlorite
• E. coli O157, Salmonella
• Very effective in challenge studies
• No slaughter authorization from USAs FDA so not
  field studies to report
• Currently within the regulatory process
  requesting label claim approval

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Sodium Chlorate

• Very little field work with E. coli O157
• Challenges of making inferences from these
  challenge models
• Needs field studies

Callaway et al., JAS 2002
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Bacteriophage

• Warrant consideration
• Potential application
• In feed
• On hide
• On meat surface
• Example is Gangagens or Ivy Natural Solutions
  products
• Applied data of in-field effects is limited
• Experimental evidence provides some promise
• Callaway et al., FPD 2008 challenge study,
  sheep
• Sheng et al., AEM 2006 challenge study, cattle

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Expectations of Interventions?
Smith DR, et al. 2001. J Food
Prot 64 (12) 1899-1903

• None will provide 100 control
• May not need 100
• USA Feedlot Study
• 73 feedlots visited twice
• Summer 15.8 positive
• Winter 5.6 positive
• Dave Smith, JFP 2001641899
• Summer 30 positive
• Winter 6.1 positive

Dr. Smiths project was supported by the National
Research Initiative of the USDA Cooperative State
Research, Education and Extension Service, grant
number 0002501.
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E. coli O157H7 Summer season prevalence
Expectations of Interventions?
Summer EVERY pen positive but highly variable
prevalence (1-80) Very few pens near the mean.
Mostly far greater or far lower prevalence than
the mean Doesnt follow expected distribution
Smith et al. J Food Prot. 2001, 64 (12) 1899-1903
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Model to Compare Prevalence of Cattle During
Summer, Winter, and with intervention
(Summer)Data-driven Simulation. Source, Dave
Smith, UNL

• Stochastic simulation model of the prevalence of
  E. coli O157H7 in live cattle with vaccination
  (_at_risk 4.5)
• 5,000 pen simulations
• (500,000 cattle)
• Intervention Summer (vaccine)
• No intervention Summer
• No intervention Winter
• Intervention efficacy 65
• Pert(50, 65, 80)

Process Control
Summer No interv.
Summer Interv.
Winter No interv.
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Model to Compare Prevalence of Cattle During
Summer, Winter, and with intervention (Summer)
Data-driven Simulation. Source, Dave Smith, UNL
Summer, no intervention
Lower risk
Higher risk
Winter, no intervention
Lower risk
Higher risk
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Model to Compare Prevalence of Cattle During
Summer, Winter, and with intervention (Summer)
Data-driven Simulation. Source, Dave Smith, UNL
Summer, no intervention
Predicted intervention distribution (summer)
Lower risk
Higher risk
Lower risk
Higher risk
Winter, no intervention
Lower risk
Higher risk
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Expectations of Interventions?

• No intervention is 100
• Need not be
• Effective turns peak-season shedding patterns
  into low-season shedding patterns
• 30 to 40 of cases in North America attributed to
  beef
• In low season, observe
• Less frequently contaminated beef
• Fewer recalls
• Less product diverted to cooking
• Fewer human illness

37
Expectations of Interventions?
Seasonal Occurrence of Human Illnesses

• Repeatable overrepresentation of cases during
  May-October
• 70 of reported cases in 6 months of the year

• In winter, prevalence in cattle, percentage
  ground beef samples positive, and human cases are
  all substantially lower compared to summer
• Target winter-time burdens. Supported by data.

38
Expectations of Interventions?

• In winter, prevalence in cattle, percentage
  ground beef samples positive, and human cases are
  all substantially lower compared to summer
• Target winter-time burdens. Supported by data.

39
Expectations of Interventions?

• If not 100 effective, then what is its purpose
• What do we want it to do?
• What can we expect it to do?
• Issues
• Purpose of pre-harvest interventions
• Different measures of prevalence in different
  studies (e.g., feces versus hides versus RAMs)
• Cross-contamination and interventions
• What can pre-harvest do for us

40
Expectations of Interventions?
Cattle Operations
Cattle
Packing Plant HACCP/PR
Various Interventions
Ground Beef
Trim for off- site grinding
Not a fail-safe system In-coming load can
overwhelm the system
41
Expectations of Interventions?
Cattle Operations
Cattle
Packing Plant HACCP/PR
Various Interventions
Ground Beef
Trim for off- site grinding
Not a fail-safe system In-coming load can
overwhelm the system
42
Expectations of Interventions?
Cattle Operations
Cattle
Packing Plant HACCP/PR
Various Interventions
Ground Beef
Trim for off- site grinding
Not a fail-safe system In-coming load can
overwhelm the system
43
Expectations of Interventions?

• Purpose not simply more is better
• To ensure burden of E. coli O157 on cattle
  presented for harvest is within manageable limits
• The in-plant series of HACCP/PR interventions
  effectively mitigate the burden on incoming
  cattle
• Efficacy need not be (or even approach) 100
• Desired efficacy depends on the burden within
  groups of cattle AND on the pathogen-mitigation
  capacity of the plant
• Linear of threshold? I suspect the latter.

44
Expectations of Interventions?
Product Efficacy (RR-1)100
67
50
30
50
Plant HACCP/PR Threshold
Incoming burden without intervention
Incoming burden with intervention
45
Expectations of Interventions?
Product Efficacy (RR-1)100
Each of these 3 scenarios fits the purpose
67
50
30
50
Plant HACCP/PR Threshold
Incoming burden without intervention
Incoming burden with intervention
46
Summary Immunomodulation as an Intervention for
E. coli O157H7

• No intervention will be 100 effective
• Scientific evidence, simulation models, and
  empirical data indicate pre-harvest interventions
  are effective
• Ultimately should reduce consumer exposure to E.
  coli O157

E. coli O157
Pre-harvest
Harvest
Consumers
47
Summary Immunomodulation as an Intervention for
E. coli O157H7

• No intervention will be 100 effective
• Scientific evidence, simulation models, and
  empirical data indicate pre-harvest interventions
  are effective
• Ultimately should reduce consumer exposure to E.
  coli O157

E. coli O157
Pre-harvest
Harvest
Consumers
48
Summary Immunomodulation as an Intervention for
E. coli O157H7
E. coli O157

• No intervention will be 100 effective
• Scientific evidence, simulation models, and
  empirical data indicate pre-harvest interventions
  are effective and fit the purpose
• Should reduce consumer exposure to E. coli O157

E. coli O157
Pre-harvest
Harvest
Consumers
49
Summary Immunomodulation as an Intervention for
E. coli O157H7
E. coli O157

• No intervention will be 100 effective
• Scientific evidence, simulation models, and
  empirical data indicate pre-harvest interventions
  are effective and fit the purpose
• Should reduce consumer exposure to E. coli O157

E. coli O157
Pre-harvest
Harvest
Consumers
50
Summary Immunomodulation as an Intervention for
E. coli O157H7
E. coli O157

• No intervention will be 100 effective
• Scientific evidence, simulation models, and
  empirical data indicate pre-harvest interventions
  are effective and fit the purpose
• Should reduce consumer exposure to E. coli O157

E. coli O157
Pre-harvest
Harvest
Consumers
51
Summary Immunomodulation as an Intervention for
E. coli O157H7

• No intervention will be 100 effective
• Scientific evidence, simulation models, and
  empirical data indicate pre-harvest interventions
  are effective and fit the purpose
• Should reduce consumer exposure to E. coli O157

E. coli O157
E. coli O157
Pre-harvest
Harvest
Consumers
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Issue How Much is Enough?

• Provide cattle with burden below threshold
  Either by
• Reducing burden from some problematic level
• Preventing groups of cattle reaching problematic
  burden
• Threshold is uncertain
• But empirical data suggest warmer months
  associated with increased risk
• Shedding in cattle and human illnesses

53
Summary

• Pre-harvest control of E. coli O157 (and
  potentially other non-O157 VTEC) is possible
• Not 100 but no need to be 100
• Purpose is within a system of multiple controls
• Pre-harvest gt harvest gt packaging gt consumers
• Effectively turn peak-season shedding patterns
  into low season shedding patterns
• Unclear what numerical contribution this has on
  risk of final product contamination
• Opportunities to evaluate products in pasture
  settings

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Acknowledgements

• SteakExpert organizers for invitation
• Patrice Arbault for co-ordination
• Your hospitality
• You for listening to me in English rather than in
  French
• Colleagues for sharing data
• Contact Information gloneragan_at_wtamu.edu
• 1 806 651-2287