Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail...

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Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling Approach Interagency Risk Assessment - L. monocytogenes in Retail Delicatessens Public Meeting Washington, DC - May 22 nd , 2013

Transcript of Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail...

Page 1: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Régis POUILLOT, DVM, PhD

FDA/CFSAN

Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment

Part 1: Design - Data Sources – Modeling Approach

Interagency Risk Assessment - L. monocytogenes in Retail Delicatessens Public Meeting

Washington, DC - May 22nd, 2013

Page 2: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

(recall) Objectives of the Model

• Fact: higher prevalence and level of Listeria monocytogenes in products that are sliced at retail vs. sliced by manufacturer

• Hypothesis: at retail– Additional cross-contaminations?

– Temperature abuses?

• Charge:– “What are the key processes that lead

to additional Listeria monocytogenes contamination / higher levels at retail?”

– “How much is the relative risk/serving reduced according to specific risk management options?”

• A model…

-3 -2 -1 0 1 2 3

0.98

50.

990

0.99

51.

000

log10(Lm concentration, MPN/g)

Cum

ulat

ive

Fra

ctio

n

retail slicedprepackaged

(Draughon, 2006)

???

2May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 3: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Outline

• Design

• Data Sources

• Implementation

• Modeling Approach

• Verification

3May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 4: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

The Retail Deli Area

FoodMeatCheeseSalad

Food workersBehavior Events

SitesSlicersCasesFood Contact SurfacesNon Food Contact SurfacesUtensils…

Listeria

NichesSlicersCases…

4May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 5: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Example Serve Customer Event

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Page 6: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Example: Serve Customer Event

Wipe Slicer

Removes some bacteria from the slicer (if any)

6May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 7: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Example: Serve Customer Event

Wipe Slicer

Wash hands & change gloves

Removes some bacteria from hands (if any). No bacteria on the gloves

7May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 8: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Example: Serve Customer Event

Wipe Slicer

Wash hands & change gloves

Potential cross contamination between gloves and case

Open case, remove chub, close case

8May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 9: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Example: Serve Customer Event

Wipe Slicer

Wash hands & change gloves

Open case, remove chub, close case

Slice on gloves

Potential cross contamination among gloves, slicer, chub and potential contamination of the product sold 9May 22nd, 2013

Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

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Example: Serve Customer Event

Wipe Slicer

Wash hands & change gloves

Open case, remove chub, close case

Slice on gloves

Touch scale

Potential cross contamination between gloves and scale

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Example: Serve Customer Event

Wipe Slicer

Wash hands & change gloves

Open case, remove chub, close case

Slice on gloves

Touch scale

Rewrap chub

Potential cross contamination between the chub and the food contact surface

11May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 12: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

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Example: Serve Customer Event

Wipe Slicer

Wash hands & change gloves

Open case, remove chub, close case

Slice on gloves

Touch scale

Rewrap chub

Potential cross contamination between the gloves and the case

Open case, replace chub, close case

12May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 13: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Example: Non Deli Time Event

Bacterial growth on products

13May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 14: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

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Page 15: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

From Retail to Risk

Dose Response ModelDose Response Model

Probability of IllnessProbability of Illness

Contamination when soldContamination when sold

Contamination when eatenContamination when eaten

Home Storage (bacterial growth)Home Storage (bacterial growth)

0 2 4 6 8 10 12

-12

-10

-8-6

-4-2

0

log10dose

log

10P

robi

llnes

s

Serving SizeServing Size

Number of Lm ingestedNumber of Lm ingested

(FAO/WHO, 2004)

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Page 16: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Outline

• Design

• Data Sources

• Implementation

• Modeling Approach

• Verification

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Page 17: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Studies Undertaken to Collect Data

Risk mapping– Expert opinion to validate where Lm occurs, what transfers likely

(FSIS Contract)– Hoelzer K, et al. (2012) Risk analysis, 32(7): 1139-56

Transfer coefficients and Slicer– Meta analysis of literature data (In-house study) – Hoelzer K, et al. (2012) International J of Food Microbiology, 157:267-77.

Persistent strains in deli departments– Longitudinal study, Cornell University (FSIS Contract)– Manuscript in preparation

Potential transfer during specific events– Mock deli using GloGerm, Virginia Tech (FSIS Contract)– Maitland J, et al. (2013) J Food Protection, 76 (2): 272-82

Food worker behavior– Observational study (FDA JIFSAN UMD collaboration)– Lubran MB, et al. (2010) J Food Protection, 73 (10):1849-57.

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Lubran MB, et al. (2010) J Food Protection, 73 (10):1849-57

Example #1: Which Sites? Which Events?Observational study in retail environment

Action No.

Action Sequence

1. 10am

Wash hands

2. Put on gloves

3. Open case

4. Pick up salami

5. Close case

6. Put salami on slicer

7. Slice salami on gloves

8. Put salami on tissue

9. Touch scale

10. Give bag to customer

Process Objects Involved

Bacteria inactivation hands

Cross contamination Case - glove

Cross contamination Case - glove

Cross contamination

PartitioningCross contamination

Chub – product sold1st slice – glove

Cross contamination Scale - glove

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Page 19: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Additional Data/Model

• Growth model– Mejholm and Dalgaard, 2009 J Food Prot, 72(10), 2132-2143.

• Temperature in deli case– Ecosure 2007 data (www.FoodRisk .org)

• Time and temperature during transport and at home– Ecosure 2007 data (www.FoodRisk .org)

• Consumption data– NHANES study, WWEIA data, 1999-2006

• Dose response model– FAO/WHO 2004

190 5 10

2

4

6

8

time (weeks)

0 5 10 15 200

2

4

6

8

10

time (days)

0

2

4

6

8

10

0 20 40 60 80 0 10 20 30 400

2

4

6

8

10

log 1

0 u

fc.m

l-1lo

g 10

ufc

.ml-1

log 1

0 u

fc.m

l-1

(e)

(g) (h)

(i)

time (days) time (days)

5.5°C 8.5°C

0 20 40 60 80-2

0

2

4

6(f)

time (weeks)

May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 20: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Outline

• Design

• Data Sources

• Implementation

• Modeling Approach

• Verification

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Page 21: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

R model

“Blue Meadow” cluster2,016 cores, 21 TFlops

Available through the Office of Science and Engineering Laboratories, CDRH - FDA

Parallel computing

ParametersExcel Data File

A Technical Challenge…

• Discrete Event model + Few bacteria in the system = Slow convergence• Each simulation: 100 Stores; 1,000,000 Servings• Currently: 126 Scenarios

Transfers: log10(T0.Baseline + 1)

To

Fro

m

Mea

tCheese

Salad

HandGlov

eFloo

rSink

Handle

Scale

CaseUtensil

Utensil

Handle

Slicer

FCSNFCSSold

Niche

RawFoodGro

wth

Mea

t

Cheese

Salad

Hand

Glove

Floor

Sink

Handle

Scale

Case

Utensil

Utensil

Handle

Slicer

FCS

NFCSSold

Wash

ed

Trash

0

2

4

6

8

10

12

14

Outputs

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Page 22: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Outline

• Design

• Data Sources

• Implementation

• Modeling Approach

• Verification

22May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 23: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Long term data gaps

• Sources of Listeria monocytogenes– Acquired data: frequency of contamination of NFCS– Data needs: better quantification: Relative contribution incoming

food vs. environment?

• Transfer events– Acquired data: better qualifications of NFCS interactions

(drains, sinks,…). – Data needs: better quantification

• Frequency of occurrence of transfers in deli settings• Number of bacteria transferred per transfer.

• Niches– Acquired data: better quantification on the

frequency of occurrence– Data needs: better quantification

• Frequency of transfer to FCS• Number of bacteria transferred

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Page 24: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

• Because of the data gaps on the relative impact of environmental contamination vs. contamination from products, we evaluated a range of retail delicatessens conditions

• Approach– Define some baseline conditions

• Baseline #1: regular environmental contaminations occur in the stores

• Baseline #2: no environmental contamination occurs in stores

• …

– Evaluate various scenarios within these baseline conditions

Modeling Approach

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Page 25: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

#1: “Multiple Niche 100W” baseline condition• Stores with regular L. monocytogenes transfer from the environment and/or niches• Incoming L. monocytogenes : from incoming products and from the

environment/niche

#2: “No Niche” baseline condition • Stores without transfer from the environment and/or niche• Incoming L. monocytogenes : from incoming products

#3: “Incoming Growth Chub” baseline condition• Stores with highly contaminated incoming product type that supports growth

#4: “Incoming Non-Growth Chub” baseline condition• Stores with highly contaminated incoming product type that does not support growth

#5: “Temperature Control” baseline condition• Stores without transfer from the environment and/or niche and with compliant

temperature control (41°F)

#6: “Niche & Temperature Control” baseline condition• Stores with regular L. monocytogenes transfer from the environment and/or niches

and with compliant temperature control (41°F)

Step 1: Definition of Baseline Conditions

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Page 26: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Step 2: Evaluation of the impact of various mitigation strategies in these contexts

• Within each of the 6 Baseline conditions– 22 Scenarios

• Answer the question (example): – Given that there is a niche in a retail deli, what are the best

mitigation strategies?

and not – What is the probability that there is a niche in the store?

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Page 27: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Approach to Risk Management Questions

• Separate slicers / counters for growth versus non growth products?– Model more than one slicer. Select slicer to use each time

customer is served based on product type.

• What is the impact of the use of “gloves” in the retail environment? – Set probability of wearing gloves to 100%

• Consider frequently touched non-food contact surfaces (e.g. case handles, scale touch pads) as food contact surfaces (i.e., required to be cleaned and sanitized every four hours)?– Change site classification to FCS

Flexibility of the Discrete Event Model

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Page 28: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

“What-If” Scenarios

• Sanitation Related Scenarios– Some NFCS cleaned FCS, Increase the effectiveness of cleaning,

No sanitation, …

• Worker Behavior Related Scenarios– No glove, No contact glove-case, Preslice products in the

morning, Do not slice product on gloves

• Growth Inhibitor Related Scenarios– All products with GI, No product with GI

• Cross contamination Related Scenarios– Separate slicers, No cross contamination

• Storage Temperature and Duration Related Scenarios– Temperature in compliance with FDA food code, Temperature set

so that no growth can occur

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Page 29: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Outline

• Design

• Data Sources

• Implementation

• Modeling Approach

• Verification

29May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Page 30: Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling.

Verifications

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General correspondence between the frequency of contamination vs. observed one (Cornell longitudinal study)

Important sources of contamination considered in the model (Risk mapping, Mock Deli study)

Control of the mass balance

Correspondence between the simulated bacterial density distribution vs. the observed one (NAFSS, 2008) (this graph)

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